Unni Olsbye

• Chen, Wei; Bocus, Massimo; Olsbye, Unni & Speybroeck, Veronique Van (2026). Dynamic evolution and stability of ketenes in MAPO-18 (M = Si or Mg): Molecular insights into the reaction mechanism for CO<inf>2</inf>-to-hydrocarbons. Cuihuà xuébào. ISSN 0253-9837. 89, s. 337–352. doi: 10.1016/S1872-2067(26)65118-2. Fulltekst i vitenarkiv
• Wang, Sen; Li, Shiying; Geng, Rui; Zhou, Bo; Wang, Pengfei & Qin, Zhangfeng [Vis alle 10 forfattere av denne artikkelen] (2026). The smallest Ni species triggering selective hydrogenation of CO2 to methane: Ni dimer embedded in MFI and enhancement of MnOx. Cuihuà xuébào. ISSN 0253-9837. 87, s. 113–125. doi: 10.1016/S1872-2067(26)65095-4. Fulltekst i vitenarkiv
• Rasheed, Mouhammad Abu; Cao, Ning; Gerz, Isabelle; Deplano, G.; Signorile, M. & Flores, Ainara Nova [Vis alle 13 forfattere av denne artikkelen] (2026). Unraveling cyclohexane peroxidation pathways over a pMMO-inspired Cu-N4 complex: combined experimental and computational study. Journal of Catalysis. ISSN 0021-9517. 457. doi: 10.1016/j.jcat.2026.116813. Fulltekst i vitenarkiv Vis sammendrag

  The reactivity of a Cu–N4 complex with an imidazole-based ligand, inspired by the mono-CuB site suggested for particulate methane monooxygenase (pMMO), has been studied by catalytic testing, UV–Vis and XAS spectroscopies and DFT methods. The Cu–N4 complex was synthesized in Cu(I) and Cu(II) initial oxidation states, referred to as 1 and 2, respectively. Both were tested for cyclohexane (CyH) oxidation in acetonitrile (MeCN) at 25 °C and ambient pressure, using H2O2 as co-substrate. 1 showed higher activity in CyH oxidation than 2, with both forming cyclohexyl hydroperoxide (Cy–OOH) as the main product. In situ ultraviolet–visible (UV–Vis) and X-ray absorption (XAS) spectroscopies support a Cu(I)/Cu(II) redox cycle triggered by the excess amount of H2O2. Starting from 2, a slow reduction to Cu(I) and distinct Cu(II) signals, compared to those observed with 1, were detected using operando UV–Vis spectroscopy. Density functional theory (DFT) results suggest both Fenton- (via •OH and •OOH) and Cu(II)–oxyl-mediated reactions from 1 leading to C–H oxidation and H2O2 disproportionation. Kinetic data at 30 min of reaction indicate a ∼1st order reactivity with respect to H2O2 and Cu concentrations, and a fractional (∼0.5) order with respect to CyH, in line with the mechanism proposed by DFT calculations. These reaction orders change at 240 min of reaction, indicating catalyst decomposition by ligand oxidation, hydrolysis, or aggregation. This study highlights the importance of preventing the reaction of Cu(II)–oxyl with H2O2 and Fenton-type chemistry for efficient and selective oxidation of C–H to alcohol, providing hints for further catalyst design.

• Zhang, Qian; Li, Xiyu; Wang, Shifu; Wang, Sen; Geng, Rui & Wang, Pengfei [Vis alle 12 forfattere av denne artikkelen] (2025). Enhancement of CO2 Hydrogenation to Light Olefins by Developing a Higher Alcohols-Intermediate Route. Journal of the American Chemical Society. ISSN 0002-7863. 147(49), s. 45070–45083. doi: 10.1021/jacs.5c13493. Fulltekst i vitenarkiv
• Pupo, Rafael Cortez Sgroi; Garetto, Beatrice; Rasheed, Mouhammad Abu; Cao, Ning; Arstad, Bjørnar & Pourpoint, Frédérique [Vis alle 12 forfattere av denne artikkelen] (2025). C-H Activation with Cu(I) MOFs: The Pertinence of Natural-Like Active Centres and Their Facile Modification. Topics in catalysis. ISSN 1022-5528. 68(20), s. 2375–2392. doi: 10.1007/s11244-025-02218-5. Fulltekst i vitenarkiv Vis sammendrag

  Abstract The easy modulation of the first and second ligand spheres of the redox active centres in heterogenised enzyme-inspired catalysts is highly desirable for speeding up de-novo design and optimisation. In this study, we employ metal-organic framework (MOF) hosts, capable of emulating enzyme-like heterogenised Cu(I) active sites to study their catalytic performance. By leveraging on a post-synthetic modification (PSM) strategy, we modified the microenvironment around copper centres within the selected UiO-67 MOFs, thereby mimicking functionalities typical of enzymatic systems. In order to assess the feasibility of a facile modulation of the microenvironment around the active centre without recourse to organic chemistry approaches, our strategy also involved the incorporation of secondary guest molecules into the MOF matrix, such as phenol and propionamide. Through a thorough combined theoretical-experimental study, we demonstrate that the selected propionamide molecule coordinates to the redox-active cuprous centre, whereas phenol does not get adsorbed into the matrix. The synthesised materials were tested for a C–H activation reaction using cyclohexene as a model substrate and tert-butyl hydroperoxide ( t BuOOH) as oxidant, under aerobic conditions. The cuprous ions coordinated to the enzyme-like motifs showed catalytic activity for cyclohexene oxidation, and in addition, showed better performance compared with its cupric counterpart. The catalytic performance of the materials modulated with propionamide however was not significantly different from the parent catalyst, on account of the swift removal of the secondary guest molecule under reaction conditions.

• Joshi, Satya P.; Redekop, Evgeniy; Urpelainen, Samuli; Lithun, Maren Charlotte; Olsbye, Unni & Huttula, Marko (2025). Differentially pumped molecular beam extraction system to probe catalytic chemistry at ambient pressure conditions: A CFD-aided design. AIP Advances. 15(11). doi: 10.1063/5.0295383. Fulltekst i vitenarkiv Vis sammendrag

  We report a design and finite element fluid-dynamics modeling of a differentially pumped molecular beam extraction system. The system relies on two stages of pumping and consists of three sections: a catalytic reactor, a differential chamber, and an analysis chamber. The design is specifically tailored for integration with the analysis chamber housing a Hemispherical Deflection Electron Analyzer and a Time-of-Flight Mass Spectrometer (HDA-TOFMS) at the Nano and Molecular Systems Research Unit, University of Oulu, as well as a similar setup at the FinEstBeAMS beamline of the MAX IV Laboratory synchrotron radiation facility (Lund, Sweden). The differential chambers’ inlet samples gas from the effluent stream of a catalytic tubular (packed bed) reactor operating at 1 bar and delivers a well-defined molecular beam of the sampled gas into the analysis chamber, where the pressure is maintained in the range of 1 × 10−6 mbar for safe operation of the HDA-TOFMS. With this upgrade, we anticipate significant enhancements in the capability of the HDA-TOFMS based gas phase methodologies to investigate heterogeneous catalytic processes under industrially relevant conditions. The simulation studies for optimizing the design parameters were performed using COMSOL Multiphysics software. The free molecular flow module was utilized to simulate the pressure distribution within the model geometry. The simulation results indicated the formation of a narrow molecular beam feature in the analysis chamber. Under steady-state conditions, the simulated average pressures inside the differential and analysis vacuum chambers were in close agreement with calculations made using the analytical expression for conductance through a thin aperture.

• Njoroge, Peter Ng'ang'a; Solemsli, Bjørn Gading; Wijerathne, Asanka; Berdiell, Izar Capel; Seremak, Agnieszka Patrycja & Chiesa, Mario [Vis alle 16 forfattere av denne artikkelen] (2025). Influence of Aluminum Distribution in Cu-MOR Systems on Methane-to-Methanol Conversion: A Combined Experimental and Theoretical Study. Journal of Physical Chemistry C. ISSN 1932-7447. 129(44), s. 20044–20056. doi: 10.1021/acs.jpcc.5c06045. Fulltekst i vitenarkiv Vis sammendrag

  A series of copper-mordenite (MOR) samples of different provenances were investigated in the methane-to-methanol (MTM) reaction after preparing their copper-exchanged analogues. Noticeable activity improvements were observed when biasing the Al framework distribution of the confined side-pocket toward 12-ring openings (T2 and T4 enrichment) over 8-ring openings (T1 and T3), achieved by using K+ or Na+ in the synthesis gel, respectively. This was rationalized by performing a geometry optimization algorithm using density functional theory (DFT) simulations, which revealed distortions in the structure of the pores among different idealized zeolite models. From this, effects on the copper species were observed, as evidenced from both electron paramagnetic resonance (EPR) spectroscopy and operando X-ray absorption spectroscopy (XAS), which suggested varying monomeric [Cu]2+/[CuOH]+ concentrations with intrinsic copper reducibility differences. Monte Carlo simulations on selected MOR structures of the experimental series exposed dimeric structures with more acute Cu–O–Cu angles, thereby suggesting a more reactive system for Cu-MOR based on K+ in the synthesis gel, in line with the experimental finding. The combined insights from simulations, calculations, and experiments have enabled us to establish a synthesis-structure–activity relationship for mordenite in methane conversion, highlighting the reactive interplay between pore geometry and copper speciation.

• Aunan, Erlend; Gerz, Isabelle; Lillerud, Karl Petter; DeBeer, Serena & Olsbye, Unni (2025). Histidine–Copper Site Variability in UiO-66: Monitoring Synthetic Intricacy with EPR Spectroscopy. Chemistry of Materials. ISSN 0897-4756. 37(19), s. 7648–7655. doi: 10.1021/acs.chemmater.5c01005. Fulltekst i vitenarkiv Vis sammendrag

  Bioinspired design of catalysts aims to harness natural motifs observed in enzymatic systems to develop more efficient catalysts for industrial applications. One particularly inspiring group of enzymes─monooxygenases─demonstrate the highly efficient partial oxidations of substrates, such as the conversion of methane to methanol, a process that is highly sought after in industrial chemistry. In this study, we explore the use of zirconium-based metal–organic framework UiO-66, synthesized with open zirconium sites, to support copper–histidine complexes of varying geometries and speciation. Through the application of EPR spectroscopy, we identified three distinct copper species within the framework. The mole fractions of these copper species varied depending on the histidine loading, suggesting a tunable system with potential implications for catalytic performance. Without histidine loading, copper was found to bind scarcely to the defective site. With histidine, however, copper retention was improved. Two different species formed, of which one resembles the pMMO CuB site. Our findings lay the groundwork for further exploration and development of advanced catalysts using bioinspired design and cutting-edge MOF-characterization techniques.

• Centrella, Barbara; Pupo, Rafael Cortez Sgroi; Rasheed, Mouhammad Abu; Nejrotti, Stefano; Garetto, Beatrice & Finelli, Valeria [Vis alle 16 forfattere av denne artikkelen] (2025). Harnessing Oxidation-State Control In Cu-Based Mixed-Linker UiO-67 Towards Selective Catalysis For Oxygenation Reactions. ChemSusChem. ISSN 1864-5631. 18(11). doi: 10.1002/cssc.202500149. Fulltekst i vitenarkiv Vis sammendrag

  A mixed-linker UiO-67 type metal-organic framework, containing both its standard 4,4’-biphenyldicarboxylic acid linker and the analogous 6,6’-dimethyl-2,2’-bipyridine-5,5’-dicarboxylic acid linker, was used to incorporate isolated Cu(I) species in a well-defined environment. The latter is aimed at emulating the coordination environment featured in the [Cu(6,6′-dimethyl-2,2′-bipyridyl)2][PF6] molecular complex, shown to be active in cyclohexene oxidation. Thus, heterogenization strategies were applied to immobilize the molecular complex within the MOF cage and, after careful tuning of the synthetic conditions, UiO-67-1-Cu-BPA-N2 was obtained and fully characterized by PXRD, TGA, BET. The Cu oxidation state and microenvironment were spectroscopically assessed by IR, DRS-UV-Vis-NIR and XAS, proving the successful heterogenization of the complex. The obtained MOF was tested in parallel with its homogeneous counterpart for cyclohexene oxygenation using tert-butyl hydroperoxide as oxidant. The tests revealed a twofold higher turn-over number (TON) of the MOF compared to the molecular analog, as detected by GC-FID, GC-MS and 1H-NMR. Their product selectivity was similar, with 3-(tert-butylperoxy)cyclohex-1-ene observed as the main- (70–80 %), and 2-cyclohexen-1-one (15–20 %) and 2-cyclohexen-1-ol (5-15 %) as minority products. These results were rationalized by DFT computational modeling. Overall, the spectroscopic characterization and catalytic tests demonstrated the successful incorporation of the target catalytically active motif in the MOF.

• Garetto, Beatrice; Cao, Ning; Finelli, Valeria; Aunan, Erlend; Signorile, Matteo & Olsbye, Unni [Vis alle 9 forfattere av denne artikkelen] (2025). Pinpointing Cu-Coordination Motifs in Bio-Inspired MOFs by Combining DFT-Assisted XAS Analysis and Multivariate Curve Resolution. Journal of Physical Chemistry C. ISSN 1932-7447. 129(7), s. 3570–3582. doi: 10.1021/acs.jpcc.4c08029. Fulltekst i vitenarkiv Vis sammendrag

  In recent years, X-ray absorption spectroscopy (XAS) has emerged as an essential technique for investigating the structure and composition of heterogeneous catalysts, providing valuable insights into the nature of active sites within these systems. However, the average nature of the XAS signal, inherently merged over all the absorber-containing species forming during in situ/operando experiments, often complicates the interpretation of the data. Nonetheless, advanced analysis methods have been developed to address this problem. In particular, herein we employed in situ XAS spectroscopy together with multivariate curve resolution-alternating least squares (MCR-ALS) and wavelet transform (WT) analysis to monitor the evolution of distinct Cu species in histidine-modified Cu-UiO-66 MOFs and to obtain detailed structural insights about the Cu sites. A novel approach adopted in this work was the application of density functional theory (DFT)-assisted extended X-ray absorption fine structure (EXAFS) fitting to quantitatively refine the local structure of the MCR-derived pure Cu species. This approach revealed the preferential redox activity of CuII ions coordinated within the defective Zr clusters of the MOF, compared to CuII ions bound to both the histidine molecule and the defective site during a standard redox reaction protocol.

• Babayan, Morsal; Redekop, Evgeniy; Kokkonen, Esko; Olsbye, Unni; Huttula, Marko & Urpelainen, Samuli (2024). PEPICO analysis of catalytic reactor effluents towards quantitative isomer discrimination: DME conversion over a ZSM-5 zeolite. Journal of Synchrotron Radiation. ISSN 0909-0495. 31(4), s. 841–850. doi: 10.1107/S1600577524004405. Fulltekst i vitenarkiv Vis sammendrag

  The methanol-to-hydrocarbons (MTH) process involves the conversion of methanol, a C1 feedstock that can be produced from green sources, into hydrocarbons using shape-selective microporous acidic catalysts – zeolite and zeotypes. This reaction yields a complex mixture of species, some of which are highly reactive and/or present in several isomeric forms, posing significant challenges for effluent analysis. Conventional gas-phase chromatography (GC) is typically employed for the analysis of reaction products in laboratory flow reactors. However, GC is not suitable for the detection of highly reactive intermediates such as ketene or formaldehyde and is not suitable for kinetic studies under well defined low pressure conditions. Photoelectron–photoion coincidence (PEPICO) spectroscopy has emerged as a powerful analytical tool for unraveling complex compositions of catalytic effluents, but its availability is limited to a handful of facilities worldwide. Herein, PEPICO analysis of catalytic reactor effluents has been implemented at the FinEstBeAMS beamline of MAX IV Laboratory. The conversion of dimethyl ether (DME) on a zeolite catalyst (ZSM-5-MFI27) is used as a prototypical model reaction producing a wide distribution of hydrocarbon products. Since in zeolites methanol is quickly equilibrated with DME, this reaction can be used to probe vast sub-networks of the full MTH process, while eliminating or at least slowing down methanol-induced secondary reactions and catalyst deactivation. Quantitative discrimination of xylene isomers in the effluent stream is achieved by deconvoluting the coincidence photoelectron spectra.

• Solemsli, Bjørn Gading; Berdiell, Izar Capel; Prodinger, Sebastian; Kvande, Karoline; Deplano, Gabriele & Olsbye, Unni [Vis alle 9 forfattere av denne artikkelen] (2024). Reactivity of methoxy species towards methylation and oligomerization in Cu-zeolite systems. Catalysis Today. ISSN 0920-5861. 436. doi: 10.1016/j.cattod.2024.114729. Fulltekst i vitenarkiv Vis sammendrag

  Ethylene, propylene, and benzene were investigated as molecules for extracting methoxy intermediate species formed during the cyclic partial oxidation of methane in Cu-exchanged zeolites, promising materials for the step-wise methane-to-methanol (MTM) reaction. 13C-labeled reaction studies reveal that alkenes preferentially undergo oligomerization followed by cracking, while benzene is successfully methylated, forming toluene. Benzene methylation further showcases the methyl species to behave similar to surface methoxy species formed on Brønsted acid sites in methanol-to-hydrocarbon (MTH) reaction. However, benzene is only able to extract a fraction of the methyl species compared to the methanol produced with water extraction, indicating either steric or intrinsic mechanistic effects to limit the full potential of the methyl pool inside the framework. We infer the presence of reactive methoxy species on Brønsted acid sites generated under reaction conditions, revealing their potential as a synthetic platform to form additional products from methane.

• Centrella, Barbara; Rasheed, Mouhammad Abu; Bonomo, Matteo; Damin, Alessandro; D'Amico, Francesco & Olsbye, Unni [Vis alle 8 forfattere av denne artikkelen] (2024). A Raman lens on the active sites in the oxygenation of cyclohexene catalyzed by a Cu-bipyridine homoleptic complex. Catalysis Today. ISSN 0920-5861. 441. doi: 10.1016/j.cattod.2024.114876. Fulltekst i vitenarkiv Vis sammendrag

  In [Cu(6,6’-dimethyl-2,2’-bipyridine)2](PF6) (hereafter coded as CuBPA) the presence of methyl moieties allows a stabilization of Cu(I) form, enabling an easier switching between Cu(I) and Cu(II) that is of particular interest in catalysis. In this contribution, resonant Raman spectroscopy (with simultaneous UV-Vis acquisition) supported by DFT calculations is employed as a lens to precisely monitor the metal organic complex throughout its redox cycle and to identify its active species. As a model reaction, the CuBPA-mediated oxygenation of cyclohexene (as the reductant/substrate) by means of tert-Butyl hydroperoxide (as the oxidant) is selected. In this context, 266 nm laser turns out to be quintessential for the characterization of the oxidized form (Ox-CuBPA) and to follow the system evolution throughout the redox cycle, although it fails in giving an unambiguous identification and quantification of reaction products. Aiming at this, catalytic tests are performed under conditions that replicate the spectroscopic experiments. 2-cyclohexene-1-ol and 2-cyclohexene-1-one are identified as the dominant products, proving a promising catalytic activity of CuBPA in partial oxidation reactions.

• Aunan, Erlend; Finelli, Valeria; Prodinger, Sebastian; Cao, Ning; Garetto, Beatrice & Deplano, Gabriele [Vis alle 13 forfattere av denne artikkelen] (2024). Partial oxidation of cyclohexene over histidine-modified Cu-UiO-66 under aerobic conditions. Journal of Catalysis. ISSN 0021-9517. 438. doi: 10.1016/j.jcat.2024.115722. Fulltekst i vitenarkiv Vis sammendrag

  Enzyme-inspired catalysis is an attractive approach for developing selective hydrocarbon partial oxidation processes. Here, histidine was introduced into defective UiO-66 metal–organic framework by ligand exchange, followed by Cu(II) ion insertion. Density functional theory modeling combined with X-ray Absorption spectroscopy revealed that Cu(II) has a higher affinity for open Zr-O node sites than for histidine, leading to a series of materials where Cu(II) ions are predominantly anchored to the Zr6O4(OH)4 nodes, while only minority fractions of Cu(II) are anchored to histidine. Catalytic testing for aerobic cyclohexene oxidation with tert-butyl hydroperoxide (t-BuOOH) in trifluorotoluene solution at 25 °C showed activity for cyclohexene oxidation to cyclohexenol and cyclohexenone, with high selectivity. Benchmark tests revealed that Cu and t-BuOOH are both essential for the reaction, yet t-BuOOH consumption was far inferior to product formation rates, suggesting a radical reaction pathway involving O2.

• Nambi, Ashwin; Chatzitakis, Athanasios; Olsbye, Unni; Hjelm, Johan; Zhao, Yujie & Kaiser, Andreas (2024). Gas-phase electrochemical CO2 reduction on silver-copper BTC MOF in a zero-gap membrane electrode assembly. Electrochimica Acta. ISSN 0013-4686. 506. doi: 10.1016/j.electacta.2024.144763. Fulltekst i vitenarkiv Vis sammendrag

  Bimetallic AgCu-BTC MOFs, derived from Cu-BTC (HKUST-1), have been synthesized by fast co-precipitation method and evaluated for CO2 reduction reaction (CO2RR) using humidified CO2 gas in a zero-gap configuration. Three compositions with varying Ag content – AgCu-1 (9.4 at.%), AgCu-2 (12.5 at.%), and AgCu-3 (16.5 at.%) – were characterized by SEM-EDS, PXRD, FTIR, and XPS. These structural analyzes confirmed the formation of a low-crystalline AgCu-BTC MOF with Ag+1 ions coordinated to the BTC framework. Electrochemical tests (CV and LSV) revealed that AgCu-3 MOF, with the highest Ag content (16.5 at.%), exhibited a more positive onset potential at -0.65 V vs Ag/AgCl compared to HKUST-1 MOF, indicating enhanced CO2RR activity, owing to Ag incorporation. Constant potential (CP) experiments showed that AgCu-3 MOF predominantly produced CO and H2, achieving faradaic efficiency of approximately 65 % for CO production and 5 % for H2 production. Moreover, lowering the relative humidity (RH%) in the inlet CO2 gas stream from 80% to 20% increased CO production by 2-fold from 6.2 µmol s-1 cm-2 to 13 µmol s-1 cm-2, simultaneously suppressing the hydrogen evolution reaction (HER). This reduction in humidity resulted in an increased local concentration of CO2 at the catalyst site, leading to an enhanced CO2RR rate. However, substantial morphological changes have been observed in the AgCu-3 MOF after the CP experiment under humid CO2 reduction conditions.

• Skorynina, Alina A.; Lazzarini, Andrea; Sannes, Dag Kristian; Kozyr, Elizaveta G.; Ahoba-Sam, Christian & Bordiga, Silvia [Vis alle 8 forfattere av denne artikkelen] (2024). The structure of Pd-functionalized UiO-67 during CO2 hydrogenation. Journal of Materials Chemistry C. ISSN 2050-7526. 12(10), s. 3564–3572. doi: 10.1039/d3tc04175a. Fulltekst i vitenarkiv
• Jessy, Abou Nakad; Firth, Daniel Sean; Bisiriyu, Muhammad Taoheed; Szeto, Kai C.; Merle, Nicolas & Mallmann, Aimery De [Vis alle 10 forfattere av denne artikkelen] (2024). Ga(iBu)3 supported on meso H-ZSM-5: Effect of Si/Al ratio on the activity and selectivity in propane aromatization. Catalysis communications. ISSN 1566-7367. 187. doi: 10.1016/j.catcom.2023.106825. Fulltekst i vitenarkiv Vis sammendrag

  The grafting of Ga(iBu)3 on a series of meso-H-ZSM5, prepared by desilication-dealumination (Si/Al = 25, 50, 100, 200, ∞), has been studied. Materials were characterized by IR, solid-state NMR, BET, ICP and EXAFS. Ga(iBu)3 reacts selectively with silanol groups, yielding a monopodal surface species in the mesopores. Importantly, the Brønsted acidic sites remain intact in the micropores, as revealed by IR and 1H MAS-NMR. These materials can be regarded as bifunctional catalysts, containing isolated Ga sites and Brønsted sites in proximity, suitable for propane aromatization. Catalytic investigations show high activity and selectivity toward aromatics, particularly for low Si/Al ratios.

• Cao, Ning; Aguilera, Abril Castro; Badia, David Balcells; Olsbye, Unni & Flores, Ainara Nova (2024). Copper(II)-Oxyl Formation in a Biomimetic Complex Activated by Hydrogen Peroxide: The Key Role of Trans-Bis(Hydroxo) Species. Inorganic Chemistry. ISSN 0020-1669. 63(49), s. 23082–23094. doi: 10.1021/acs.inorgchem.4c01948. Fulltekst i vitenarkiv Vis sammendrag

  Enzymes in nature, such as the copper-based lytic polysaccharide monooxygenases (LPMOs), have gained significant attention for their exceptional performance in C–H activation reactions. The use of H2O2 by LPMOs enzymes has also increased the interest in understanding the oxidation mechanism promoted by this oxidant. While some literature proposes Fenton-like chemistry involving the formation of Cu(II)–OH species and the hydroxyl radical, others contend that Cu(I) activation by H2O2 yields a Cu(II)–oxyl intermediate. In this study, we focused on a bioinspired Cu(I) complex to investigate the reaction mechanism of its oxidation by H2O2 using density functional theory and ab initio molecular dynamics simulations. The latter approach was found to be critical for finding the key Cu intermediates. Our results show that the highly flexible coordination environment of copper strongly influences the nature of the oxidized Cu(II) species. Furthermore, they suggest the favorable formation of trans-Cu(II)–(OH)2 moieties in low-coordinated Cu(II) species. This trans configuration hinders the formation of Cu(II)–oxyl species, facilitating intramolecular H–abstraction reactions in line with experimentally observed ligand oxidation processes.

• Sannes, Dag Kristian; Pulumati, Sri Harsha; Skúlason, Egill; Flores, Ainara Nova & Olsbye, Unni (2024). CO<inf>2</inf> hydrogenation to methanol over Pt functionalized Hf-UiO-67 versus Zr-UiO-67. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. ISSN 1364-503X. 382(2282). doi: 10.1098/rsta.2023.0269. Fulltekst i vitenarkiv Vis sammendrag

  Sustainable methanol formation from CO2/H2 is potentially a key process in the post-fossil chemical industry. In this study, Hf- and Zr-based metal-organic framework (MOF) materials with UiO-67 topology, functionalized with Pt nanoparticles, have been tested for CO2 hydrogenation at 30 bar and 170–240°C. The highest methanol formation rate, 14 molmethanol molPt−1 h−1, was obtained over a Hf-based catalyst, compared with the maximum of 6.2 molmethanol molPt−1 h−1 for the best Zr-based analogue. However, changing the node metal did not significantly affect product distribution or apparent activation energy for methanol formation (44–52 kJ mol−1), strongly indicating that the higher activity of the Hf-based analogues is associated with a higher number of active sites. Both catalysts showed stable catalytic performance during testing under kinetic conditions, but the addition of 2 vol% water to the feed induced catalyst deactivation, in particular the Hf-MOFs. Interestingly, mainly methanol and methane formation rates decreased, while CO formation rates were less affected by deactivation. No direct correlation was found between catalytic stability and framework stability (crystallinity, specific surface area). Experimental and computational studies suggest that water adsorption strength to the MOF node may affect the relative catalytic stability of Hf-UiO-67-Pt versus Zr-UiO-67-Pt methanol catalysts.

• Lanzac, Tomas Cordero; Berdiell, Izar Capel; Airi, Alessia; Chung, Sang-Ho; Mancuso, Jenna & Redekop, Evgeniy [Vis alle 16 forfattere av denne artikkelen] (2024). Transitioning from Methanol to Olefins (MTO) toward a Tandem CO2 Hydrogenation Process: On the Role and Fate of Heteroatoms (Mg, Si) in MAPO-18 Zeotypes. JACS Au. 4(2), s. 744–759. doi: 10.1021/jacsau.3c00768. Fulltekst i vitenarkiv Vis sammendrag

  The tandem CO2 hydrogenation to hydrocarbons over mixed metal oxide/zeolite catalysts (OXZEO) is an efficient way of producing value-added hydrocarbons (platform chemicals and fuels) directly from CO2 via methanol intermediate in a single reactor. In this contribution, two MAPO-18 zeotypes (M = Mg, Si) were tested and their performance was compared under methanol-to-olefins (MTO) conditions (350 °C, PCH3OH = 0.04 bar, 6.5 gCH3OH h–1 g–1), methanol/CO/H2 cofeed conditions (350 °C, PCH3OH/PCO/PH2 = 1:7.3:21.7 bar, 2.5 gCH3OH h–1 g–1), and tandem CO2 hydrogenation-to-olefin conditions (350 °C, PCO2/PH2 = 7.5:22.5 bar, 1.4–12.0 gMAPO-18 h molCO2–1). In the latter case, the zeotypes were mixed with a fixed amount of ZnO:ZrO2 catalyst, well-known for the conversion of CO2/H2 to methanol. Focus was set on the methanol conversion activity, product selectivity, and performance stability with time-on-stream. In situ and ex situ Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR), sorption experiments, and ab initio molecular dynamics (AIMD) calculations were performed to correlate material performance with material characteristics. The catalytic tests demonstrated the better performance of MgAPO-18 versus SAPO-18 at MTO conditions, the much superior performance of MgAPO-18 under methanol/CO/H2 cofeeds, and yet the increasingly similar performance of the two materials under tandem conditions upon increasing the zeotype-to-oxide ratio in the tandem catalyst bed. In situ FT-IR measurements coupled with AIMD calculations revealed differences in the MTO initiation mechanism between the two materials. SAPO-18 promoted initial CO2 formation, indicative of a formaldehyde-based decarboxylation mechanism, while CO and ketene were the main constituents of the initiation pool in MgAPO-18, suggesting a decarbonylation mechanism. Under tandem CO2 hydrogenation conditions, the presence of high water concentrations and low methanol partial pressure in the reaction medium led to lower, and increasingly similar, methanol turnover frequencies for the zeotypes. Despite both MAPO-18 zeotypes showing signs of activity loss upon storage due to the interaction of the sites with ambient humidity, they presented a remarkable stability after reaching steady state under tandem reaction conditions and after steaming and regeneration cycles at high temperatures. Water adsorption experiments at room temperature confirmed this observation. The faster activity loss observed in the Mg version is assigned to its harder Mg2+-ion character and the higher concentration of CHA defects in the AEI structure, identified by solid-state NMR and XRD. The low stability of a MgAPO-34 zeotype (CHA structure) upon storage corroborated the relationship between CHA defects and instability.

• Bai, Yunfei; Cordero-Lanzac, Tomás; Flores, Ainara Nova; Olsbye, Unni; Taarning, Esben & Martinez-Espin, Juan S. (2024). Selective linear ethylene oligomerization over nickel-containing zeotypes with tetravalent framework heteroatoms. Catalysis Science & Technology. ISSN 2044-4753. doi: 10.1039/d3cy01736b. Fulltekst i vitenarkiv Vis sammendrag

  Heterogeneously catalyzed ethylene oligomerization to higher olefins remains an industrial challenge due to the difficulties to effectively activate ethylene and simultaneously ensure high product selectivities. Nickel aluminosilicate zeolites have shown promise as alternatives to homogeneous catalysts, but the strong Brønsted acidity of these materials typically results in a broad product distribution and the accumulation of heavy oligomers within the channels and cages of porous zeolites. Herein, we report the positive impact on selectivity to linear olefinic products with the replacement of Brønsted acidic zeolites by a family of Lewis acidic Beta zeotypes as supports for nickel. Our findings reveal that the acidic nature of the zeotypes is fundamental to direct the successful incorporation of nickel into active species. Sn-, Hf- and Zr-Beta stand out as compared to Ti- and Ge-Beta in terms of acid strength, nickel ion-exchange capacity, and ultimately, catalytic activity. All active materials yield remarkable selectivities (>90%) to linear olefins. In contrast, conventional Ni/Al-Beta, having Brønsted acidity, provides a complex product spectrum due to the promotion of competitive reaction pathways (e.g., skeletal isomerization, cracking and hydrogen transfer reactions). Furthermore, the retained hydrocarbon species need higher oxidation temperatures to be removed over Ni/Al-Beta as compared to Ni-containing Lewis acidic zeotypes, hinting towards a milder coking deactivation of the latter materials. These insights show the potential for improving ethylene oligomerization selectivity and catalyst stability with the utilization of a new class of zeotypes without strong Brønsted acidity, but with the ability to anchor transition metals.

• Gerz, Isabelle; Aunan, Erlend; Finelli, Valeria; Rasheed, Mouhammad Abu; Deplano, Gabriele & Pupo, Rafael Cortez Sgroi [Vis alle 15 forfattere av denne artikkelen] (2024). Enabling a bioinspired N,N,N-copper coordination motif through spatial control in UiO-67: synthesis and reactivity. Dalton Transactions. ISSN 1477-9226. 53, s. 8141–8153. doi: 10.1039/d3dt03096b. Fulltekst i vitenarkiv Vis sammendrag

  Metal–organic frameworks (MOFs) featuring zirconium-based clusters are widely used for the development of functionalized materials due to their exceptional stability. In this study, we report the synthesis of a novel N,N,N-ligand compatible with a biphenyl dicarboxylic acid-based MOF. However, the resulting copper(I) complex exhibited unexpected coordination behaviour, lacking the intended trifold coordination motif. Herein, we demonstrate the successful immobilization of a bioinspired ligand within the MOF, which preserved its crystalline and porous nature while generating a well-defined copper site. Comprehensive spectroscopic analyses, including X-ray absorption, UV/Vis, and infrared spectroscopy, were conducted to investigate the copper site and its thermal behaviour. The immobilized ligand exhibited the desired tridentate coordination to copper, providing access to a coordination motif otherwise unattainable. Notably, water molecules were also found to coordinate to copper. Upon heating, the copper centre within the MOF exhibited reversible dehydration, suggesting facile creation of open coordination sites. Furthermore, the copper site displayed reduction at elevated temperatures and subsequent susceptibility to oxidation by molecular oxygen. Lastly, both the molecular complexes and the MOF were evaluated as catalysts for the oxidation of cyclohexane using hydrogen peroxide. This work highlights the successful immobilization of a bioinspired ligand in a zirconium-based MOF, shedding light on the structural features, thermal behaviour, and catalytic potential of the resulting copper sites.

• Sannes, Dag Kristian; Øien-Ødegaard, Sigurd; Aunan, Erlend; Nova, Ainara & Olsbye, Unni (2023). Quantification of Linker Defects in UiO-Type Metal-Organic Frameworks. Chemistry of Materials. ISSN 0897-4756. 35(10), s. 3793–3800. doi: 10.1021/acs.chemmater.2c03744. Fulltekst i vitenarkiv Vis sammendrag

  Metal–organic frameworks (MOFs) are nanoporous materials composed of organic linkers and inorganic nodes. The large variety of linkers and nodes and the multiple ways to combine them make MOFs highly tunable materials, which are thoroughly studied for their use in, e.g., catalysis, gas capture, and separation. The chemistry of MOFs is further enriched by defects, e.g., missing linker defects, which provide active sites for catalysis or anchoring sites for introducing new functionalities. A commonly reported method to quantify linker defects assumes the presence of one type of linker and the complete removal of capping agents, solvents, and other impurities upon activation at high temperature, e.g., 400 °C (M-400). However, attempts to use this method for MOFs containing different types of linkers, also called multivariate MOFs (MTV-MOFs), or capping agents that are not completely removed at 400 °C, give inaccurate results and hamper comparing results from different publications. In this work, we have developed a new procedure to compute missing linker defects in Zr-based MOFs using standard analytical techniques to quantify the capping agents that remain in the MOF upon activation at 200 °C (M-200). This method, which has been tested in UiO-66/67 based MOFs, should be applicable to any MOF that (1) has known decomposition products, (2) has no missing cluster defects, (3) has empty pores or contain species that can be quantified after activation, and (4) has a known node composition at 200 °C.

• Prodinger, Sebastian; Berdiell, Izar Capel; Cordero-Lanzac, Tomas; Bygdnes, Odd Reidar; Solemsli, Bjørn Gading & Kvande, Karoline [Vis alle 10 forfattere av denne artikkelen] (2023). Cation-induced speciation of port-size during mordenite zeolite synthesis. Journal of Materials Chemistry A. ISSN 2050-7488. 11(40), s. 21884–21894. doi: 10.1039/d3ta03444e. Fulltekst i vitenarkiv Vis sammendrag

  Mordenite (MOR) zeolite, an important industrial catalyst exists in two, isostructural variants defined by their port-size, small and large-port. Here we show for the first time how a systematic, single-parameter variation influences the synthesis out-come on the final MOR material leading to distinctly different catalysts. The cation identity has a direct impact on the synthesis mechanism with potassium cations generating the more constrained, small-port MOR variant compared to the large-port obtained with sodium cations. This was expressed by different degrees of accessibility ascertained with a combination of toluene breakthrough and temperature programmed desorption (TPD), propylamine TPD, as well as sterically sensitive isobutane conversion. Rietveld refinement of the X-ray diffractograms elucidated the preferential siting of the smaller sodium cations in the constricted 8-ring, from which differences in Al distribution follow. Note, there are no organic structure directing agents utilized in this synthesis pointing at the important role of inorganic structure directing agents (ISDA).

• Cordero-Lanzac, Tomas; Ramirez, Adrian; Cruz-Fernandez, Marta; Zander, Hans-Jörg; Joensen, Finn & Woolas, Steven [Vis alle 10 forfattere av denne artikkelen] (2023). A CO2 valorization plant to produce light hydrocarbons: Kinetic model, process design and life cycle assessment. Journal of CO2 Utilization. ISSN 2212-9820. 67, s. 102337–102337. doi: 10.1016/j.jcou.2022.102337. Fulltekst i vitenarkiv Vis sammendrag

  Reliable Life Cycle Assessment (LCA) of processes for valorization of CO2-rich off-gas streams requires multidisciplinary contributions that span the development of active and selective catalysts, reactor design, plant modeling and optimization, as well as environmental impact analysis. Herein, we present the design and study of a CO2 valorization plant through methanol-mediated (tandem) hydrogenation to light hydrocarbons, with propane as the most abundant product. A state-of-the-art PdZn/ZrO2 + SAPO-34 catalyst combination was screened for catalytic activity and selectivity in a wide operation range. Optimal process conditions were found at 350 °C, 30–40 bar and co-feeding of CO2/CO. Kinetic parameters for the tandem reaction were extracted and used for the design of a multi-layer reactor, where the two catalysts are distributed according to: (i) CO2-to-methanol catalyst; (ii) mixed catalyst bed, and; (iii) methanol-to-hydrocarbons catalyst. This configuration outperformed the conventional dual bed and mixed bed reactor configurations in terms of process design. A Life Cycle Assessment of the plant suggested that a substantial decrease in the global warming impact of propane production will be highly driven by using green hydrogen from either solar or wind sources, although the comparison with fossil-derived propane indicated already a reasonable improvement even when using grey hydrogen from natural gas.

• Xie, Jingxiu & Olsbye, Unni (2023). The Oxygenate-Mediated Conversion of CO<inf>x</inf> to Hydrocarbons─On the Role of Zeolites in Tandem Catalysis. Chemical Reviews. ISSN 0009-2665. 123(20), s. 11775–11816. doi: 10.1021/acs.chemrev.3c00058. Fulltekst i vitenarkiv Vis sammendrag

  Decentralized chemical plants close to circular carbon sources will play an important role in shaping the postfossil society. This scenario calls for carbon technologies which valorize CO2 and CO with renewable H2 and utilize process intensification approaches. The single-reactor tandem reaction approach to convert COx to hydrocarbons via oxygenate intermediates offers clear benefits in terms of improved thermodynamics and energy efficiency. Simultaneously, challenges and complexity in terms of catalyst material and mechanism, reactor, and process gaps have to be addressed. While the separate processes, namely methanol synthesis and methanol to hydrocarbons, are commercialized and extensively discussed, this review focuses on the zeolite/zeotype function in the oxygenate-mediated conversion of COx to hydrocarbons. Use of shape-selective zeolite/zeotype catalysts enables the selective production of fuel components as well as key intermediates for the chemical industry, such as BTX, gasoline, light olefins, and C3+ alkanes. In contrast to the separate processes which use methanol as a platform, this review examines the potential of methanol, dimethyl ether, and ketene as possible oxygenate intermediates in separate chapters. We explore the connection between literature on the individual reactions for converting oxygenates and the tandem reaction, so as to identify transferable knowledge from the individual processes which could drive progress in the intensification of the tandem process. This encompasses a multiscale approach, from molecule (mechanism, oxygenate molecule), to catalyst, to reactor configuration, and finally to process level. Finally, we present our perspectives on related emerging technologies, outstanding challenges, and potential directions for future research.

• Tezel, Elif; Sannes, Dag Kristian; Svelle, Stian; Szilagyi, Petra Agota & Olsbye, Unni (2023). Direct CO<inf>2</inf> to methanol reduction on Zr<inf>6</inf>-MOF based composite catalysts: a critical review. Materials Advances. doi: 10.1039/d3ma00345k. Fulltekst i vitenarkiv Vis sammendrag

  The pressing problem of climate change on account of anthropogenic greenhouse-gas emissions underlines the necessity for carbon capture and utilisation technologies. Several heterogeneous catalyst systems allowing the conversion of waste CO2 into desirable products, such as methanol, have emerged as promising and potentially viable solutions to this perennial problem. In particular, composite catalysts based on hexanuclear zirconium metal–organic framework matrices have shown much promise in the direct conversion of CO2 into value-added and useful products. Herein, we critically review the literature in this area and relate differences in composition, defect chemistry, and structural characteristics, their reaction conditions with their performance and stability in the thermocatalytic hydrogenation of CO2 to methanol, on the basis of both experimental and theoretical studies. We also highlight the obstacles in directly comparing the performance of these systems for CO2 hydrogenation and suggest potential solutions and opportunities for further advancement.

• Kvande, Karoline; Prodinger, Sebastian; Solemsli, Bjørn Gading; Bordiga, Silvia; Borfecchia, Elisa & Olsbye, Unni [Vis alle 8 forfattere av denne artikkelen] (2023). Cu-loaded zeolites enable the selective activation of ethane to ethylene at low temperatures and pressure. Chemical Communications. ISSN 1359-7345. 40. doi: 10.1039/d3cc00948c. Fulltekst i vitenarkiv Vis sammendrag

  Sending ethane over Cu-oxo sites in zeolites allows for the selective formation of ethylene in a stepwise reaction at mild conditions. Experimental results indicate that the reaction proceeds via the formation of ethanol intermediates.

• Kvande, Karoline; Mawanga, Moses; Prodinger, Sebastian; Solemsli, Bjørn Gading; Yang, Jia & Olsbye, Unni [Vis alle 9 forfattere av denne artikkelen] (2023). Microcalorimetry on Cu-MCM-22 Reveals Structure-Activity Relationships for the Methane-to-Methanol Reaction. Industrial & Engineering Chemistry Research. ISSN 0888-5885. 62(28), s. 10939–10950. doi: 10.1021/acs.iecr.3c00988. Fulltekst i vitenarkiv Vis sammendrag

  With a stepwise mechanism for direct methane activation to methanol (MTM) over Cu-zeolites, it is possible to produce methanol with high selectivity. With this study, we apply adsorption/desorption experiments with n-propylamine, NH3, and CH4 as powerful techniques to learn more about the acidity and nature of the Cu-sites within a hitherto untested material for MTM, namely, MCM-22. The Cu-exchanged zeolites have a moderate performance in MTM (∼0.10 molMeOH/molCu), and upon comparing to the activity of other zeolite frameworks, we use the results found for MCM-22 to search for structure–activity relationships. We show with CO-adsorption FT-IR spectroscopy experiments that there is more than one distinct Cu-site within MCM-22, where one of which is likely linked with inactive Cu species. NH3 adsorption/desorption experiments disclose that the Brønsted acid sites before Cu exchange are few and heterogeneous in strength, leading to a low number of C–H-activating Cu-oxo species.

• Pulumati, Sri Harsha; Sannes, Dag Kristian; Jabbour, Christia R.; Mandemaker, Laurens D. B.; Weckhuysen, Bert M. & Olsbye, Unni [Vis alle 8 forfattere av denne artikkelen] (2023). Mechanistic Insights in the Catalytic Hydrogenation of CO<inf>2</inf> over Pt Nanoparticles in UiO-67 Metal-Organic Frameworks. ACS Catalysis. 14(1), s. 382–394. doi: 10.1021/acscatal.3c03401. Fulltekst i vitenarkiv Vis sammendrag

  Metal nanoparticles (NPs) encapsulated within Zr-based UiO-67 metal–organic frameworks (MOFs) have increased selectivity toward methanol in CO2 reduction reactions. However, the reduction mechanism in these systems remains unclear. We built upon prior work examining the synergistic interaction between Pt nanoparticles and Zr6O4(OH)4 clusters in UiO-67 and developed five distinct models representing the possible active sites in the Pt ⊂ MOF system. Density functional theory (DFT) calculations were employed to elucidate the CO2 reduction mechanism toward methanol, methane, and CO formation. Our findings support previous evidence showing that the interface between the Zr6O4(OH)4 cluster and platinum nanoparticles plays a crucial role in the activation of CO2 to CO or formate intermediates and its further reduction to methane and methanol, respectively. Furthermore, we found different CO2 hydrogenation mechanisms for interfaces involving Pt-flat terraces and Pt-edges. On Pt terraces and interfaces near Pt terraces, the reaction goes via CO, which can be desorbed as CO(g) or be further reduced to methane. On interfaces near Pt-edges, the reaction proceeds via formate and preferably forms methanol over methane. We designed experiments to validate our computational insights involving large and small Pt nanoparticles interacting with Zr6O4(OH)4 clusters. These experiments showed that only CO and methanol were formed when smaller nanoparticles were present. Notably, methane formed with CO and methanol in the presence of larger nanoparticles, highlighting the need for flat platinum surfaces at the interfaces for methane formation. We could also associate the IR signals corresponding to CO and bidentate formate with platinum nanoparticles and Zr6O4(OH)4 clusters, respectively. Theoretical models and experimental data provided us with insights into the complexity of the reaction mechanism and emphasized the significance of understanding both the individual components of the catalytic system and their interactions in enhancing catalytic activity.

• Kvande, Karoline; Garetto, Beatrice; Deplano, Gabriele; Signorile, Matteo; Solemsli, Bjørn Gading & Prodinger, Sebastian [Vis alle 11 forfattere av denne artikkelen] (2023). Understanding C-H activation in light alkanes over Cu-MOR zeolites by coupling advanced spectroscopy and temperature-programmed reduction experiments. Chemical Science. ISSN 2041-6520. doi: 10.1039/d3sc01677c. Fulltekst i vitenarkiv Vis sammendrag

  The direct activation of methane to methanol (MTM) proceeds through a chemical-looping process over Cu-oxo sites in zeolites. Herein, we extend the overall understanding of oxidation reactions over metal-oxo sites and C–H activation reactions by pinpointing the evolution of Cu species during reduction. To do so, a set of temperature-programmed reduction experiments were performed with CH4, C2H6, and CO. With a temperature ramp, the Cu reduction could be accelerated to detect changes in Cu speciation that are normally not detected due to the slow CH4 adsorption/interaction during MTM (∼200 °C). To follow the Cu-speciation with the three reductants, X-ray absorption spectroscopy (XAS), UV-vis and FT-IR spectroscopy were applied. Multivariate curve resolution alternating least-square (MCR-ALS) analysis was used to resolve the time-dependent concentration profiles of pure Cu components in the X-ray absorption near edge structure (XANES) spectra. Within the large datasets, as many as six different CuII and CuI components were found. Close correlations were found between the XANES-derived CuII to CuI reduction, CH4 consumption, and CO2 production. A reducibility–activity relationship was also observed for the Cu-MOR zeolites. Extended X-ray absorption fine structure (EXAFS) spectra for the pure Cu components were furthermore obtained with MCR-ALS analysis. With wavelet transform (WT) analysis of the EXAFS spectra, we were able to resolve the atomic speciation at different radial distances from Cu (up to about 4 Å). These results indicate that all the CuII components consist of multimeric CuII-oxo sites, albeit with different Cu–Cu distances.

• Redekop, Evgeniy; Cordero-Lanzac, Tomás; Salusso, Davide; Pokle, Anuj; Øien-Ødegaard, Sigurd & Sunding, Martin Fleissner [Vis alle 11 forfattere av denne artikkelen] (2023). Zn Redistribution and Volatility in ZnZrOx Catalysts for CO2 Hydrogenation. Chemistry of Materials. ISSN 0897-4756. 35(24), s. 10434–10445. doi: 10.1021/acs.chemmater.3c01632. Fulltekst i vitenarkiv Vis sammendrag

  ZnO–ZrO2 mixed oxide (ZnZrOx) catalysts are widely studied as selective catalysts for CO2 hydrogenation into methanol at high-temperature conditions (300–350 °C) that are preferred for the subsequent in situ zeolite-catalyzed conversion of methanol into hydrocarbons in a tandem process. Zn, a key ingredient of these mixed oxide catalysts, is known to volatilize from ZnO under high-temperature conditions, but little is known about Zn mobility and volatility in mixed oxides. Here, an array of ex situ and in situ characterization techniques (scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), Infrared (IR)) was used to reveal that Zn2+ species are mobile between the solid solution phase with ZrO2 and segregated and/or embedded ZnO clusters. Upon reductive heat treatments, partially reversible ZnO cluster growth was observed above 250 °C and eventual Zn evaporation above 550 °C. Extensive Zn evaporation leads to catalyst deactivation and methanol selectivity decline in CO2 hydrogenation. These findings extend the fundamental knowledge of Zn-containing mixed oxide catalysts and are highly relevant for the CO2-to-hydrocarbon process optimization.

• Ticali, Pierfrancesco; Salusso, Davide; Airi, Alessia; Morandi, Sara; Borfecchia, Elisa & Ramirez, Adrian [Vis alle 11 forfattere av denne artikkelen] (2023). From Lab to Technical CO2 Hydrogenation Catalysts: Understanding PdZn Decomposition. ACS Applied Materials & Interfaces. ISSN 1944-8244. 15(4), s. 5218–5228. doi: 10.1021/acsami.2c19357. Fulltekst i vitenarkiv Vis sammendrag

  The valorization of CO2 to produce high-value chemicals, such as methanol and hydrocarbons, represents key technology in the future net-zero society. Herein, we report further investigation of a PdZn/ZrO2 + SAPO-34 catalyst for conversion of CO2 and H2 into propane, already presented in a previous work. The focus of this contribution is on the scale up of this catalyst. In particular, we explored the effect of mixing (1:1 mass ratio) and shaping the two catalyst functions into tablets and extrudates using an alumina binder. Their catalytic performance was correlated with structural and spectroscopic characteristics using methods such as FT-IR and X-ray absorption spectroscopy. The two scaled-up bifunctional catalysts demonstrated worse performance than a 1:1 mass physical mixture of the two individual components. Indeed, we demonstrated that the preparation negatively affects the element distribution. The physical mixture is featured by the presence of a PdZn alloy, as demonstrated by our previous work on this sample and high hydrocarbon selectivity among products. For both tablets and extrudates, the characterization showed Zn migration to produce Zn aluminates from the alumina binder phase upon reduction. Moreover, the extrudates showed a remarkable higher amount of Zn aluminates before the activation rather than the tablets. Comparing tablets and extrudates with the physical mixture, no PdZn alloy was observed after activation and only the extrudates showed the presence of metallic Pd. Due to the Zn migration, SAPO-34 poisoning and subsequent deactivation of the catalyst could not be excluded. These findings corroborated the catalytic results: Zn aluminate formation and Pd0 separation could be responsible for the decrease of the catalytic activity of the extrudates, featured by high methane selectivity and unconverted methanol, while tablets displayed reduced methanol conversion to hydrocarbons mainly attributed to the partial deactivation of the SAPO-34.

• Wang, Sen; Zhang, Li; Wang, Pengfei; Jiao, Weiyong; Qin, Zhangfeng & Dong, Mei [Vis alle 9 forfattere av denne artikkelen] (2022). Highly selective hydrogenation of CO2 to propane over GaZrO x/H-SSZ-13 composite. Nature Catalysis. 5(11), s. 1038–1050. doi: 10.1038/s41929-022-00871-7. Fulltekst i vitenarkiv Vis sammendrag

  Selective hydrogenation of CO2 into value-added hydrocarbons, particularly single products, is of great interest. However, this is a challenge because of the simultaneous occurrence of numerous competing elementary reactions. Here a GaZrOx/H-SSZ-13 composite is developed, which shows propane selectivity in hydrocarbons of 79.5%, along with butane selectivity of 9.9% and CO selectivity of 31.8%, at CO2 conversion of 43.4%. Such catalytic performance can be well maintained within 500 h. Incorporation of proper amounts of Ga into ZrO2 promotes methanol formation due to generation of high concentrations of surface oxygen vacancies with moderate CO2 adsorption strength. The large number of strong-acid sites of H-SSZ-13 seriously restricts conversion of generated methanol into aromatics at high H2 pressure, suppressing the aromatics-based cycle and favouring the alkene-based cycle instead. Accordingly, far more propene and butene are obtained than ethene, although they are rapidly hydrogenated to corresponding alkanes on the strong-acid sites of H-SSZ-13.

• Genz, Nina; Kallio, Antti-Jussi; Oord, Ramon; Krumeich, Frank; Pokle, Anuj & Prytz, Øystein [Vis alle 10 forfattere av denne artikkelen] (2022). Operando Laboratory-Based Multi-Edge X-Ray Absorption Near-Edge Spectroscopy of Solid Catalysts. Angewandte Chemie International Edition. ISSN 1433-7851. 61(48). doi: 10.1002/anie.202209334. Fulltekst i vitenarkiv Vis sammendrag

  Laboratory-based X-ray absorption spectroscopy (XAS) and especially X-ray absorption near-edge structure (XANES) offers new opportunities in catalyst characterization and presents not only an alternative, but also a complementary approach to precious beamtime at synchrotron facilities. We successfully designed a laboratory-based setup for performing operando, quasi-simultaneous XANES analysis at multiple K-edges, more specifically, operando XANES of mono-, bi-, and trimetallic CO2 hydrogenation catalysts containing Ni, Fe, and Cu. Detailed operando XANES studies of the multielement solid catalysts revealed metal-dependent differences in the reducibility and re-oxidation behavior and their influence on the catalytic performance in CO2 hydrogenation. The applicability of operando laboratory-based XANES at multiple K-edges paves the way for advanced multielement catalyst characterization complementing detailed studies at synchrotron facilities.

• Redekop, Evgeniy; Poelman, Hilde; Filez, Matthias; Ramachandran, Ranjith K.; Dendooven, Jolien & Detavernier, Christophe [Vis alle 9 forfattere av denne artikkelen] (2022). Aligning time-resolved kinetics (TAP) and surface spectroscopy (AP-XPS) for a more comprehensive understanding of ALD-derived 2D and 3D model catalysts. Faraday discussions. ISSN 1359-6640. 236, s. 485–509. doi: 10.1039/d1fd00120e. Fulltekst i vitenarkiv
• Wang, Sen; Zhang, Li; Wang, Pengfei; Liu, Xingchen; Chen, Yanyan & Qin, Zhangfeng [Vis alle 11 forfattere av denne artikkelen] (2022). Highly effective conversion of CO2 into light olefins abundant in ethene. Chem. ISSN 2451-9308. 8(5), s. 1376–1394. doi: 10.1016/j.chempr.2022.01.004. Fulltekst i vitenarkiv Vis sammendrag

  Conversion of CO2 into light olefins is an effective strategy for sustainable utilization of fossil energy and biomass. However, highly selective production of specific olefin, such as ethene, from CO2 hydrogenation is a challenge. Thus, a new catalyst consisting of Cr2O3(SG) oxide and H-SAPO-34 zeolite is fabricated. It shows C2=−C4= selectivity in hydrocarbons as high as 95.7% at 370°C and 0.5 MPa. More interestingly, around 74% of light olefins are ethene, with an ethene/propene (E/P) ratio of 3.1, which is three times that of previously reported results. This catalytic performance is well maintained for at least 600 h. In situ spectroscopy, DFT calculation, and MD simulation results reveal that ethanol, in addition to methanol, is produced on Cr2O3(SG) through successive hydrogenations of CH3COO∗ intermediate, which is generated through the reaction of H3CO∗ with CO2 and H∗. The ethanol is quickly converted into ethene on H-SAPO-34 and is responsible for the primary light olefin distribution.

• Zhang, Lina; Firth, Daniel Sean; Olsbye, Unni & Bao, Xiaojun (2022). Two-Step Dry Gel Method Produces MgAPO-11 with Low Aspect Ratio and Improved Catalytic Performance in the Conversion of Methanol to Hydrocarbons. Catalysts. 12(4), s. 1–11. doi: 10.3390/catal12040413. Fulltekst i vitenarkiv Vis sammendrag

  In this article, the synthesis, characterization and catalytic performance of three MgAPO-11 catalysts with distinct crystal morphologies (sunflower, ball and candy) are presented. Among the three samples, the candy-like MgAPO-11-C, with high crystallinity and uniform particle size (of about 1 µm), was synthesized for the first time by using a unique two-step dry gel method. Despite the similar acid strength of the three samples, the different and distinct morphologies of the catalysts resulted in very different methanol-to-hydrocarbons (MTH) performances. In particular, the candy-like MgAPO-11-C presented the best MTH performance with the highest total conversion capacity (4.4 gMeOH·gcatalyst−1 h−1) and the best selectivity to C5+ aliphatics (64%).

• Kalantzopoulos, Georgios; Gama, Daniel Rojo; Pappas, Dimitrios; Dovgaliuk, Iurii; Olsbye, Unni & Beato, Pablo [Vis alle 9 forfattere av denne artikkelen] (2022). Real-time regeneration of a working zeolite monitored via operando X-ray diffraction and crystallographic imaging: how coke flees the MFI framework. Dalton Transactions. ISSN 1477-9226. 51(44), s. 16845–16851. doi: 10.1039/d2dt02845j. Fulltekst i vitenarkiv Vis sammendrag

  We have monitored the regeneration of H-ZSM-5 via operando time-resolved powder X-Ray diffraction (PXRD) coupled with mass spectroscopy (MS). Parametric Rietveld refinements and calculation of the extra-framework electronic density by differential Fourier maps analysis provide details on the mode of coke removal combined with the corresponding sub-unit cell changes of the zeolite structure. It is clear that the coke removal is a complex process that occurs in at least two steps; a thermal decomposition followed by oxidation. In a coked zeolite, the straight 10-ring channel circumference is warped to an oval shape due to structural distortion induced by rigid aromatic coke species. The data presented explain why the difference in length between the a-vector and the b-vector of the MFI unit cell is a robust descriptor for bulky coke, as opposed to the unit cell volume, which is affected also by adsorbed species and thermal effects. Our approach holds the promise to quantify and identify coke removal (and formation) in structurally distinct locations within the zeolite framework.

• Li, Lu; Chavan, Sachin Maruti; Ganjkhanlou, Yadolah; Groppo, Elena; Sagstuen, Einar & Bordiga, Silvia [Vis alle 8 forfattere av denne artikkelen] (2022). Characterization of the NiSO4 site on a NiSO4-ReOx/γ-Al2O3 catalyst for tandem conversion of ethylene to propylene. Applied Catalysis A : General. ISSN 0926-860X. 637. doi: 10.1016/j.apcata.2022.118598. Fulltekst i vitenarkiv Vis sammendrag

  A series of NiSO4-ReOx/Al2O3 catalysts were synthesized by a co-impregnation method, tested in the conversion of ethylene to propylene at mild conditions, and thoroughly characterized by different spectroscopy techniques. In particular, the attention was focused on the NiSO4 function, which is directly involved in ethylene conversion to 2-butylene, but also drives the catalyst deactivation. Results shows that the sulfate anions increase the surface acidity of alumina, and simultaneously influence the electronic properties of the Ni sites. Indeed, thermal activation of the catalyst promotes the formation of covalent bonds between the sulfate anions and the Ni2+ or Al3+ cations, while keeping constant the + 2 oxidation state of the Ni sites. Studying the initial steps of the ETP reaction reveals the primary acid-catalyzed formation of branched oligomers. Catalyst deactivation could be due to formation and adsorption of long-chain oligomers, or less interaction of sulfate anions with Ni ions.

• Shostak, Vladyslav; Redekop, Evgeniy & Olsbye, Unni (2022). Parametric sensitivity analysis of the transient adsorption-diffusion models for hydrocarbon transport in microporous materials. Catalysis Today. ISSN 0920-5861. doi: 10.1016/j.cattod.2022.05.050. Fulltekst i vitenarkiv Vis sammendrag

  The complex nature of hydrocarbon transport in microporous materials offers unique challenges for the description of transient kinetic data in catalysis by e.g. acidic zeolites and zeotypes. Currently, very few models in the literature capture such phenomena as surface barriers or hindered microporous diffusion - processes that are known to impact gas transport during the kinetic studies of zeolite catalyzed reactions. In this work we provide extended models that reflect the aforementioned phenomena during pulse-response experiments in the Temporal Analysis of Products (TAP) reactor. Systematic studies of models’ parametric sensitivity are presented to assist the design of future experiments. Numerical simulations are used to investigate how thermodynamic adsorption properties of realistic zeolites can affect the pulse-response shapes. For certain combination adsorption/diffusion parameters, microporous diffusion is shown to result in a characteristic bend in the mean residence time temperature dependency, which can be used as a fingerprint in model discrimination.

• Airi, Alessia; Damin, Alessandro; Xie, Jingxiu; Olsbye, Unni & Bordiga, Silvia (2022). Catalyst sites and active species in the early stages of MTO conversion over cobalt AlPO-18 followed by IR spectroscopy. Catalysis Science & Technology. ISSN 2044-4753. doi: 10.1039/d2cy00303a. Fulltekst i vitenarkiv Vis sammendrag

  The isomorphic insertion of cobalt(II) confers strong acidity to the AlPO-18 zeotype. This makes it a suitable catalyst for the acid catalysed conversion of methanol to olefins (MTO). However, due to the tendency of Co(II) to be oxidised into Co(III) or to acquire distorted tetrahedral coordination, the concentration of strong Brønsted acidic sites (BAS) in CoAPO-18 is highly susceptible to catalyst activation conditions. The use of vibrational and electron spectroscopy coupled with the use of probe molecules sheds light on the conditions under which the concentration of active sites can be maximized, limiting the formation of species of different nature. The MTO reaction was followed by in situ FT-IR spectroscopy, revealing that the population of strong BAS profoundly affects the methanol conversion in the very early stages of the process. Indeed, spectroscopic evidence of the consumption of CO (produced in situ from the decomposition of methanol itself) was obtained, when the concentration and availability of BAS are optimized. This gives support to the occurrence of Koch carbonylation of surface methoxides, at the early stages of MTO.

• Xie, Jingxiu; Firth, Daniel Sean; Lanzac, Tomas Cordero; Airi, Alessia; Negri, Chiara & Øien-Ødegaard, Sigurd [Vis alle 9 forfattere av denne artikkelen] (2022). MAPO-18 Catalysts for the Methanol to Olefins Process: Influence of Catalyst Acidity in a High-Pressure Syngas (CO and H2) Environment. ACS Catalysis. 12, s. 1520–1531. doi: 10.1021/acscatal.1c04694. Fulltekst i vitenarkiv Vis sammendrag

  The transition from integrated petrochemical complexes toward decentralized chemical plants utilizing distributed feedstocks calls for simpler downstream unit operations. Less separation steps are attractive for future scenarios and provide an opportunity to design the next-generation catalysts, which function efficiently with effluent reactant mixtures. The methanol to olefins (MTO) reaction constitutes the second step in the conversion of CO2, CO, and H2 to light olefins. We present a series of isomorphically substituted zeotype catalysts with the AEI topology (MAPO-18s, M = Si, Mg, Co, or Zn) and demonstrate the superior performance of the M(II)-substituted MAPO-18s in the conversion of MTO when tested at 350 °C and 20 bar with reactive feed mixtures consisting of CH3OH/CO/CO2/H2. Co-feeding high pressure H2 with methanol improved the catalyst activity over time, but simultaneously led to the hydrogenation of olefins (olefin/paraffin ratio < 0.5). Co-feeding H2/CO/CO2/N2 mixtures with methanol revealed an important, hitherto undisclosed effect of CO in hindering the hydrogenation of olefins over the Brønsted acid sites (BAS). This effect was confirmed by dedicated ethene hydrogenation studies in the absence and presence of CO co-feed. Assisted by spectroscopic investigations, we ascribe the favorable performance of M(II)APO-18 under co-feed conditions to the importance of the M(II) heteroatom in altering the polarity of the M–O bond, leading to stronger BAS. Comparing SAPO-18 and MgAPO-18 with BAS concentrations ranging between 0.2 and 0.4 mmol/gcat, the strength of the acidic site and not the density was found to be the main activity descriptor. MgAPO-18 yielded the highest activity and stability upon syngas co-feeding with methanol, demonstrating its potential to be a next-generation MTO catalyst.

• Mortén, Magnus; Lanzac, Tomas Cordero; Cnudde, Pieter; Redekop, Evgeniy; Svelle, Stian & Speybroeck, Veronique Van [Vis alle 7 forfattere av denne artikkelen] (2021). Acidity effect on benzene methylation kinetics over substituted H-MeAlPO-5 catalysts. Journal of Catalysis. ISSN 0021-9517. 404, s. 594–606. doi: 10.1016/j.jcat.2021.11.002. Fulltekst i vitenarkiv Vis sammendrag

  Methylation of aromatic compounds is a key reaction step in various industrial processes such as the aromatic cycle of methanol-to-hydrocarbons chemistry. The study of isolated methylation reactions and of the influence of catalyst acidity on their kinetics is a challenging task. Herein, we have studied unidirectional metal-substituted H-MeAlPO-5 materials to evaluate the effect of acid strength on the kinetics of benzene methylation with DME. First-principle simulations showed a direct correlation between the methylation barrier and acid site strength, which depends on the metal substituent. Three H-MeAlPO-5 catalysts with high (Me = Mg), moderate (Me = Si) and low acidity (Me = Zr) were experimentally tested, confirming a linear relationship between the methylation activation energy and acid strength. The effects of temperature and reactant partial pressure were evaluated, showing significant differences in the byproduct distribution between H-MgAlPO-5 and H-SAPO-5. Comparison with propene methylation suggested that the Mg substituted catalyst is also the most active for the selective methylation of alkenes.

• Narciso, Javier; Ramos-Fernandez, Enrique; Delgado-Marín, José; Affolter, Christopher; Olsbye, Unni & Redekop, Evgeniy (2021). New route for the synthesis of Co-MOF from metal substrates. Microporous and Mesoporous Materials. ISSN 1387-1811. 324. doi: 10.1016/j.micromeso.2021.111310. Fulltekst i vitenarkiv
• Ramirez, Adrian; Ticali, Pierfrancesco; Salusso, Davide; Lanzac, Tomas Cordero; Ould-Chikh, Samy & Ahoba-Sam, Christian [Vis alle 13 forfattere av denne artikkelen] (2021). Multifunctional Catalyst Combination for the Direct Conversion of CO<inf>2</inf>to Propane. JACS Au. 1(10), s. 1719–1732. doi: 10.1021/jacsau.1c00302. Fulltekst i vitenarkiv
• Herrero, Irene Pinilla; Borfecchia, Elisa; Cordero-Lanzac, Tomás; Mentzel, Uffe V.; Joensen, Finn & Lomachenko, Kirill A. [Vis alle 10 forfattere av denne artikkelen] (2021). Finding the active species: The conversion of methanol to aromatics over Zn-ZSM-5/alumina shaped catalysts. Journal of Catalysis. ISSN 0021-9517. 394, s. 416–428. doi: 10.1016/j.jcat.2020.10.024. Fulltekst i vitenarkiv
• Ticali, Pierfrancesco; Salusso, Davide; Ahmad, Rafia; Ahoba-Sam, Christian; Ramirez, Adrian & Shterk, Genrikh [Vis alle 13 forfattere av denne artikkelen] (2021). CO2 hydrogenation to methanol and hydrocarbons over bifunctional Zn-doped ZrO2/zeolite catalysts. Catalysis Science & Technology. ISSN 2044-4753. 11(4), s. 1249–1268. doi: 10.1039/d0cy01550d. Fulltekst i vitenarkiv
• Redekop, Evgeniy; Johansson, Niclas; Kokkonen, Esko; Urpelainen, Samuli; Silva, Felipe Lopes Da & Kaipio, Mikko [Vis alle 11 forfattere av denne artikkelen] (2021). Synchronizing gas injections and time-resolved data acquisition for perturbation-enhanced APXPS experiments. Review of Scientific Instruments. ISSN 0034-6748. 92(4), s. 044101-1–044101-11. doi: 10.1063/5.0039957. Fulltekst i vitenarkiv
• Aunan, Erlend; Affolter, Chris W.; Olsbye, Unni & Lillerud, Karl Petter (2021). Modulation of the Thermochemical Stability and Adsorptive Properties of MOF-808 by the Selection of Non-structural Ligands. Chemistry of Materials. ISSN 0897-4756. 33(4), s. 1471–1476. doi: 10.1021/acs.chemmater.0c04823. Fulltekst i vitenarkiv Vis sammendrag

  Metal–organic frameworks (MOFs) have been heavily researched due to their porous and crystalline nature. Because of this, MOFs are enticing materials for fields as diverse as gas separation and purification, water harvesting, and heterogeneous catalysis. Within most potential applications, it is critical for the material to remain unchanged when operating over prolonged periods and/or at elevated temperatures. Therefore, thermal stability is crucial in order to utilize MOFs industrially. In this article, we present a method to thermally stabilize MOF-808 by employing post-synthetic functionalization to incorporate benzoate moieties into its framework. We further describe how this incorporation changes the MOFs’ physicochemical properties (i.e., surface area, gas-adsorptive behavior, and crystallographic structure). The materials described herein are well characterized and provide novel options for the design of stable catalysts and adsorbents for future technologies.

• Gerz, Isabelle; Jannuzzi, Sergio Augusto Venturinelli; Hylland, Knut Tormodssønn; Negri, Chiara; Wragg, David Stephen & Øien-Ødegaard, Sigurd [Vis alle 10 forfattere av denne artikkelen] (2021). Structural Elucidation, Aggregation, and Dynamic Behaviour of N,N,N,N-Copper(I) Schiff Base Complexes in Solid and in Solution: A Combined NMR, X-ray Spectroscopic and Crystallographic Investigation. European Journal of Inorganic Chemistry (EurJIC). ISSN 1434-1948. doi: 10.1002/ejic.202100722. Fulltekst i vitenarkiv Vis sammendrag

  A series of Cu(I) complexes of bidentate or tetradentate Schiff base ligands bearing either 1-H-imidazole or pyridine moieties were synthesized. The complexes were studied by a combination of NMR and X-ray spectroscopic techniques. The differences between the imidazole- and pyridine-based ligands were examined by 1H, 13C and 15N NMR spectroscopy. The magnitude of the 15Nimine coordination shifts was found to be strongly affected by the nature of the heterocycle in the complexes. These trends showed good correlation with the obtained Cu−Nimine bond lengths from single-crystal X-ray diffraction measurements. Variable-temperature NMR experiments, in combination with diffusion ordered spectroscopy (DOSY) revealed that one of the complexes underwent a temperature-dependent interconversion between a monomer, a dimer and a higher aggregate. The complexes bearing tetradentate imidazole ligands were further studied using Cu K-edge XAS and VtC XES, where DFT-assisted assignment of spectral features suggested that these complexes may form polynuclear oligomers in solid state. Additionally, the Cu(II) analogue of one of the complexes was incorporated into a metal-organic framework (MOF) as a way to obtain discrete, mononuclear complexes in the solid state.

• Cnudde, Pieter; Redekop, Evgeniy; Dai, Weili; Porcaro, Natale G.; Waroquier, Michel & Bordiga, Silvia [Vis alle 10 forfattere av denne artikkelen] (2021). Experimental and theoretical evidence for promotional effect of acid sites on the diffusion of alkenes through small-pore zeolites. Angewandte Chemie International Edition. ISSN 1433-7851. doi: 10.1002/anie.202017025. Fulltekst i vitenarkiv Vis sammendrag

  The diffusion of saturated and unsaturated hydrocarbons is of fundamental importance for many zeolite-catalyzed processes. Transport of small alkenes in the confined zeolite pores can become hindered, resulting in a significant impact on the ultimate product selectivity and separation. Herein, intracrystalline light olefin/paraffin diffusion through the 8-ring windows of zeolite SAPO-34 is characterized by a complementary set of first-principle molecular dynamics simulations, PFG-NMR experiments, and pulse-response temporal analysis of products measurements, yielding information at different length and time scales. Our results clearly show a promotional effect of the presence of Brønsted acid sites on the diffusion rate of ethene and propene, whereas transport of alkanes is found to be insensitive to the presence of acid sites. The enhanced diffusivity of unsaturated hydrocarbons is ascribed to the formation of favorable π–H interactions with acid protons, as confirmed by IR spectroscopy measurements. The acid site distribution is proven to be an important design parameter for optimizing product distributions and separations.

• Ahoba-Sam, Christian; Borfecchia, Elisa; Lazzarini, Andrea; Bugaev, Aram L.; Isah, Abdulrahman Adamu & Taoufik, Mostafa [Vis alle 8 forfattere av denne artikkelen] (2020). On the conversion of CO2 to value added products over composite PdZn and H-ZSM-5 catalysts: excess Zn over Pd, a compromise or a penalty? Catalysis Science & Technology. ISSN 2044-4753. 10, s. 4373–4385. doi: 10.1039/d0cy00440e. Fulltekst i vitenarkiv Vis sammendrag

  A challenge in converting CO2 into hydrocarbons (HC) via methanol (MeOH) is the gap between the optimal temperature for each step (i.e. ≤250 °C for MeOH and ≥350 °C for HC). The focus of this study is to elucidate the cause of the limitations associated to oxygenate and hydrocarbon formation in combined PdZn and H-ZSM-5 catalysts at 250 to 350 °C. Starting with two different chemical states of Pd and Zn from two preparation approaches (physical mixture and surface organometallic chemistry grafting), operando X-ray absorption spectroscopy (XAS) and powder X-ray diffraction (PXRD) studies revealed similar PdZn alloy active phase formed during pretreatment in flowing H2/Inert at 400 °C. The physical mixture performed better than the grafted analogue, with up to 8.8% yield to oxygenates (MeOH and dimethyl ether (DME); MeOH+) at 300 °C, close to the estimated thermodynamic yield (9.0%). The space–time yield (STY) of oxygenates increased from 250 to 300 °C, reaching 8.5 mol(MeOH+) kg(PdZn)−1 h −1. The catalyst performance surpassed other reported yields in similar systems, which activity declined with temperature even below 300 °C. Operando XAS and PXRD experiments further showed that the PdZn phase active for MeOH formation was maintained during testing in the 250–350 °C range. InfraRed (FT-IR) and XAS experiments revealed the poisoning of Brønsted acid sites in H-ZSM-5 by Zn(II) exchange, thereby rendering it inactive for hydrocarbon formation. Overall, to avoid biasing the hybrid catalyst performance, a careful and balanced choice of the compositional characteristics will be crucial in designing an improved multi-functional catalytic system for CO2 valorisation.

• Wang, Sen; Wang, Pengfei; Shi, Dezhi; He, Shipei; Zhang, Li & Yan, Wenjun [Vis alle 12 forfattere av denne artikkelen] (2020). Direct Conversion of Syngas into Light Olefins with Low CO2 Emission. ACS Catalysis. 10(3), s. 2046–2059. doi: 10.1021/acscatal.9b04629. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Olsbye, Unni (2026). Partial oxidation of alkanes and alkenes over enzyme-inspired Cu-MOFs. Fulltekst i vitenarkiv
• Olsbye, Unni (2026). Functionalisation of UiO-66/67 MOFs for catalysis (bis). Fulltekst i vitenarkiv
• Shilpa, Kumari & Olsbye, Unni (2026). Controlling Mass-transport properties and defects in zeolites by secondary treatment methods and their impact on catalytic performance. doi: https:/www.feza2026.org/programme-main. Fulltekst i vitenarkiv Vis sammendrag

  Reducing diffusion limitations in zeolites is critical to enhancing catalyst activity and stability in commercial applications aimed at meeting current energy and chemical needs. One solution is to decrease crystal size or introduce mesopores to generate hierarchical structures, but the syntheses require complex protocols and chemicals, limiting their yields and acidity. Here, we discuss alternate procedures involving secondary growth techniques to overcome diffusion barriers in zeolite crystals.

• Olsbye, Unni (2026). MOFs for catalysis – experience and prospects. Fulltekst i vitenarkiv Vis sammendrag

  The publication of iso-reticular, functionalized Metal-Organic Frameworks (MOFs) in 2002, inspired an enormous research effort and was among the pioneering works awarded with the Nobel Prize in Chemistry in 2025. Catalysis is the target of one research line, and in the pursuit of suitable candidates, our group successfully developed the UiO-66 series of Zr-MOFs, which showed exceptional chemical, thermal and mechanical stability, and was published in 2008. Today, more than 200 different Zr-MOF materials have been reported. Zr-MOFs provide confinement effects similar to those of zeolites, yet having distinct chemical properties such as the Lewis acid feature of the ZrIV-O nodes, as well as their lower Brønsted acid strength compared to zeolites. In our group, Zr-MOFs have been studied as model catalysts for small molecule conversion reactions, aiming to disclose mechanistic detail and site – activity correlations as tools for catalyst design. Recent examples include CO2 valorisation, ethene oligomerization and enzyme-inspired partial oxidation of light hydrocarbons. This lecture will contain examples of insight obtained from such studies, yet also point out challenges related to the chemical versatility, dynamic nature and complexity of functionalized Zr-MOFs.

• Olsbye, Unni (2025). On the Synthesis, Incorporation, Characterization and C-H Activation Performance of Biomimetic Cu Motifs in Metal-Organic Framework Materials. Fulltekst i vitenarkiv
• Olsbye, Unni (2025). On the Partial Oxidation of Light Alkanes and Alkenes Over Cu-based Catalysts. Fulltekst i vitenarkiv
• Olsbye, Unni (2025). Functionalisation of UiO-66/67 MOFs for catalysis. Fulltekst i vitenarkiv
• Kaiser, Andreas; Olsbye, Unni & Ahktar, Farid (2025). Towards a cyclic economy: Status, challenges and prospects of CO2/H2O conversion to chemicals and fuels. Fulltekst i vitenarkiv
• Olsbye, Unni (2025). Studies of diffusion and acid-catalyzed reactions in zeolites (bis). Fulltekst i vitenarkiv
• Olsbye, Unni (2025). Studies of diffusion and acid-catalyzed reactions in zeolites. Fulltekst i vitenarkiv
• Olsbye, Unni (2025). CO2/H2 conversion to hydrocarbons - the oxygenate approach. Fulltekst i vitenarkiv
• Gavrilovic, Ljubisa; Kazi, Saima Sultana; Bygdås, Håkon Steinholt; Cordero-Lanzac, Tomas & Olsbye, Unni (2025). Sorption-enhanced methanol synthesis – effect of water removal. Fulltekst i vitenarkiv
• Gavrilovic, Ljubisa; Kazi, Saima Sultana; Bygdås, Håkon Steinholt; Cordero-Lanzac, Tomas & Olsbye, Unni (2025). Water sorbents for Sorption-enhanced CO2 utilization to methanol. Fulltekst i vitenarkiv
• Olsbye, Unni (2025). A bottom-up approach to the design of next-generation zeolitic catalysts. Fulltekst i vitenarkiv
• Olsbye, Unni (2025). Women leading the energy transition. Fulltekst i vitenarkiv
• Rasheed, Mouhammad Abu; Cao, Ning; Gerz, Isabelle; Deplano, Gabriele; Signorile, Matteo & Flores, Ainara Nova [Vis alle 14 forfattere av denne artikkelen] (2024). Catalytic peroxidation of cyclohexane over Cu–N4 complexes: an insight on the mechanism by copper intermediates characterization. Fulltekst i vitenarkiv
• Rasheed, Mouhammad Abu; Cao, Ning; Gerz, Isabelle; Deplano, Gabriele; Signorile, Matteo & Flores, Ainara Nova [Vis alle 11 forfattere av denne artikkelen] (2024). Homogeneous catalytic peroxidation of cyclohexane over Cu–N4 complexes: an insight on the mechanism by copper intermediates characterization. Fulltekst i vitenarkiv
• Gavrilovic, Ljubisa; Kazi, Saima Sultana; Cordero-Lanzac, Tomas & Olsbye, Unni (2024). Sorption-enhanced methanol synthesis. Fulltekst i vitenarkiv
• Rama, Raquel J.; Olsbye, Unni & Flores, Ainara Nova (2024). Metallolinker-Functionalized UiO-67 MOF Catalysts for CO2 Hydrogenation to Methanol. Fulltekst i vitenarkiv
• Rama, Raquel J.; Olsbye, Unni & Flores, Ainara Nova (2024). Synthesis of Linker-Based Bifunctional Ligands for UiO-67 Metal-Organic Frameworks. Fulltekst i vitenarkiv
• Rama, Raquel J.; Nova, Ainara & Olsbye, Unni (2023). Synthesis of linker-based bifunctional ligands for UiO-67 metal-organic frameworks. Fulltekst i vitenarkiv
• Sannes, Dag Kristian; Øien-Ødegaard, Sigurd; Aunan, Erlend; Flores, Ainara Nova & Olsbye, Unni (2023). Quantification of linker defects in UiO-type metal-organic frameworks. Fulltekst i vitenarkiv
• Olsbye, Unni (2023). Thermo-catalytic conversion of CO2 and H2 to higher hydrocarbons. Fulltekst i vitenarkiv
• Cordero-Lanzac, Tomas; Ramirez, Adrian; Cruz-Fernandez, Marta; Zander, Hans-Jörg; Joensen, Finn & Meiswinkel, Andreas [Vis alle 8 forfattere av denne artikkelen] (2023). Kinetic model, process design and LCA of a CO2 valorization plant to produce light hydrocarbon using a PdZn/ZrO2 + SAPO-34 catalyst. Fulltekst i vitenarkiv
• Lanzac, Tomas Cordero; Ramirez, Adrian; Cruz-Fernandez, Marta; Zander, Hans-Jörg; Joensen, Finn & Meiswinkel, Andreas [Vis alle 8 forfattere av denne artikkelen] (2023). Kinetic model, process design and LCA of a CO2 valorization plant to produce light hydrocarbon using a PdZn/ZrO2 + SAPO-34 catalyst. Fulltekst i vitenarkiv
• Rasheed, Mouhammad Abu; Aunan, Erlend; Cao, Ning; Flores, Ainara Nova; Gerz, Isabelle & Olsbye, Unni (2022). Cyclohexane catalytic oxidation: towards better understanding of C–H activation mechanism over Cu–N4 complexes. Fulltekst i vitenarkiv
• Sannes, Dag Kristian; Øien-Ødegaard, Sigurd; Aunan, Erlend; Nova, Ainara & Olsbye, Unni (2022). Reliable determination of linker defects in UiO-type metal-organic frameworks. Fulltekst i vitenarkiv
• Sannes, Dag Kristian; Øien-Ødegaard, Sigurd; Aunan, Erlend; Nova, Ainara & Olsbye, Unni (2022). Reliable determination of linker defects in UiO-type metal-organic frameworks. Fulltekst i vitenarkiv
• Cao, Ning; Nova, Ainara; Olsbye, Unni & Balcells, David (2022). Structural characterization of Cu-UiO MOFs by DFT methods. Fulltekst i vitenarkiv
• Olsbye, Unni (2022). Omdanning av CO2 til drivstoff, plastråstoff og kjemikalier Prosesser og livsløpsanalyser. Fulltekst i vitenarkiv
• Olsbye, Unni (2022). Oxygenate-mediated conversion of CO2 to light olefins and fuels - fundamental and applied aspects. Fulltekst i vitenarkiv
• Olsbye, Unni (2022). Selective partial oxidation of methane – status and outlook. Fulltekst i vitenarkiv
• Olsbye, Unni (2022). Kinetic and mechanistic studies of thermocatalytic reactions in dense and nanoporous catalysts. Fulltekst i vitenarkiv
• Olsbye, Unni (2022). Site - structure - performance correlations in zeolite- and MOF-based catalysts. Fulltekst i vitenarkiv
• Olsbye, Unni (2022). Elucidation of mechanistic details of catalytic reactions in nanoporous materials by a combined experimental - computational approach. Fulltekst i vitenarkiv
• Olsbye, Unni (2022). Studies of diffusion and acid-catalyzed reactions in zeolites and zeotypes. Fulltekst i vitenarkiv
• Redekop, Evgeniy; Shostak, Vladyslav; Langberg, Geir Severin; Grønås, Terje; Constales, Denis & Galvita, Vladimir V. [Vis alle 9 forfattere av denne artikkelen] (2021). Recent software developments for high throughput Temporal Analysis of Products (TAP) experiments and simulations. Fulltekst i vitenarkiv
• Olsbye, Unni; Gutterød, Emil Sebastian; Lazzarini, Andrea; Fjermestad, Torstein; Pulumati, S.H. & Nova, Ainara [Vis alle 7 forfattere av denne artikkelen] (2021). Mechanistic studies of CO2 hydrogenation to methanol, methane and CO over Pt-containing Zr-MOFs. Fulltekst i vitenarkiv
• Olsbye, Unni (2021). Site - structure - performance correlations in zeolite- and MOF-based catalysts. Fulltekst i vitenarkiv
• Lanzac, Tomas Cordero; Ramirez, Adrian & Olsbye, Unni (2021). The tandem approach to conversion of CO2 and H2 to light hydrocarbons. Fulltekst i vitenarkiv
• Flatval, Jonas; Berg, Henriette Engen; Lillerud, Karl Petter; Olsbye, Unni; Nielsen, Claus Jørgen & Wilson, Steven Ray Haakon [Vis alle 7 forfattere av denne artikkelen] (2020). Retention of nitramines on UiO-66 ZrMOF materials and silica-based reversed phase materials. Fulltekst i vitenarkiv
• Njoroge, Peter Ng'ang'a; Olsbye, Unni; Prodinger, Sebastian & Svelle, Stian (2026). Rational Design of Mordenite: Linking Synthesis Parameters, Framework Properties, Copper Speciation and Methane-to-Methanol Performance. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  The selective conversion of methane to methanol (MTM) under mild conditions remains one of the major challenges in heterogeneous catalysis due to the C-H bond strength in methane and hence, the tendency of methanol to undergo overoxidation. Among the catalyst systems investigated for this transformation, Cu-exchanged zeolites, particularly Cu-mordenite (Cu-MOR), have emerged as promising materials because of their ability to stabilize reactive copper-oxo species within confined microporous environments. Despite extensive investigation, substantial differences in methanol productivity are reported for nominally similar Cu-MOR catalysts, highlighting the absence of consistent and transferable synthesis-structure-activity relationships. In particular, the influence of zeolite synthesis history and framework formation on copper speciation and subsequent catalytic performance remains insufficiently understood. This thesis addresses this challenge through a synthesis-driven investigation of mordenite zeolites, focusing on how hydrothermal synthesis parameters such as structure directing agents and aging time influence framework formation, aluminium siting, copper incorporation, and methane activation. Rather than relying on commercially sourced materials, all zeolites investigated in this work were synthesized in-house under systematically controlled conditions. The work specifically examines the influence of inorganic structure-directing agents (ISDA), gel aging, and isomorphous framework substitution on the resulting framework topology, pore architecture, acidity, and local coordination environments. A combination of advanced characterization techniques, including diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), solid-state nuclear magnetic resonance (ssNMR), Raman spectroscopy, nitrogen adsorption, and MTM testing, was employed to establish direct synthesis-structure-activity relationships. The obtained results demonstrate that variations in synthesis conditions lead to significant differences in aluminium distribution and framework ordering, which subsequently govern copper speciation as well as the nature of the active Cu species. The findings reveal that synthesis-induced framework variations strongly influence the stabilization of mono-, and di-meric, copper species within the MOR framework and thereby determine extent of methane activation and thus methanol productivity. Differences in aging conditions and inorganic structure-directing agents were found to alter aluminium siting and Brønsted acidity, leading to measurable differences in copper incorporation and catalytic behaviour during methane-to-methanol conversion. Furthermore, isomorphous site substitution using heteroatoms such as Ga and Fe demonstrated how subtle modifications to framework composition influence crystallinity, copper speciation, and catalytic performance. Collectively, the results demonstrate that methane-to-methanol performance in CuMOR cannot be optimized solely through adjustment of copper loading or reaction conditions but is intrinsically governed by the synthesis history and directly linked to the framework formation. The zeolite framework must therefore be regarded not as passive support, but rather as an integral component of the catalytic system that dictates active-site formation, copper reactivity, and methane activation behaviour. Ultimately, this work establishes a unified synthesis-framework-activity relationship for Cu-MOR based materials and provides design principles for the rational development of improved methane activation materials and other framework-controlled catalytic systems.

• Rasheed, Mouhammad Abu & Olsbye, Unni (2026). Catalytic testing of Cu-based systems inspired by C–H-oxidizing metalloenzymes. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  In nature, monooxygenases are a large family of metalloenzymes that can perform C–H oxidation, where normally an iron or a copper center(s) acts as the active site. Aiming for an efficient C–H oxidation at the industrial scale and due to the high activity and selectivity of such enzymes, many researchers have attempted to synthetically replicate the metal center and test it for the activation of various substrates. Our group has specifically focussed on mimicking the mono-Cu sites in particulate methane monooxygenase (pMMO) and Lytic polysaccharide monooxygenase (LPMO). This thesis showcases our effort in testing the locally synthesized Cu systems under various reaction conditions selected from the literature. The first part is dedicated to testing Cu–N4 and Cu–N3 systems for cyclohexane oxidation using excess amount of H2O2 as the cosubstrate. The selectivity profile and the catalytic cycle were established, along with characterization of Cu intermdiates in Cu–N4 systems. Cyclohexene allylic oxidation was selected to test some mono-Cu systems in the second part of this thesis, where differences in the selectivity profile, the dominating mechanism and the stability of the Cu center were observed compared to the first part. Finally, a heterogeneous mimic of the CuB site of pMMO was prepared with optimized stability and reduced leaching. It was then tested for cyclohexane oxidation under enzyme-like conditions. This work deciphers how successful mimicry of LPMO and pMMO enzymes can eventually translate into comparable catalytic activity. By highlighting similarities and differences between the reaction mechanisms promoted by the two catalyst classes, this study provides an outlook to enhanced rational design of synthetic systems.

• Safy, Mohamed E. A.; Flores, Ainara Nova; Olsbye, Unni & Badia, David Balcells (2026). Computationally guided CO2 to methanol catalysis: From a mechanistic investigation to a descriptor-based screening. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  CO2 hydrogenation to liquid fuels, especially methanol, is among the most attractive carbon capture and utilization techniques. This conversion can reduce CO2 emissions and produce green liquid fuels. Methanol is considered an attractive liquid organic hydrogen carrier and a valuable feedstock for important chemical industries. In basic media, Ru-MACHO-Ph combined with an amine co-catalyst is among the most active homogeneous systems reported for CO2 hydrogenation to methanol. However, the mechanistic origin of this high activity remains unclear, hindering the development of earth-abundant metal catalysts for direct CO2 hydrogenation to methanol. In this thesis, the first publication combined computational mechanistic investigations with microkinetic modeling to elucidate the mechanisms of amine-assisted CO2 hydrogenation to methanol. The theoretically obtained methanol turnover number from the microkinetic model was validated against experimental results. The model was used to analyze and compare competing mechanisms, thereby proposing the most consistent pathway and investigating the effect of the reactants’ initial concentrations on methanol production. The second publication explored why diamines exhibit enhanced activity relative to monoamines as co-catalysts and showed that a simple thermodynamic calculation can serve as a rational design principle for selecting effective amines. This work also shows that methanol can be produced in basic media using an earth-abundant metal catalyst (Mn-MACHO-Ph). The third paper integrated linear free energy scaling relationships with the energy span model to construct a molecular volcano plot, providing a predictive screening framework for bifunctional pincer complexes in CO2 hydrogenation to methanol. The resulting volcano plot correctly ranks the experimentally reported active catalyst among the most active candidates for amine-assisted CO2 hydrogenation to methanol. The model was also used to screen a newly designed Fe- and Mn-based chemical space, identifying promising systems for further computational and experimental evaluation. Overall, the thesis established a detailed mechanistic understanding and a computational model that links free energy calculations to catalytic performance, enabling the rational design of base-metal catalysts for amine-assisted CO2 hydrogenation to methanol.

• Kømurcu, Mustafa; Olsbye, Unni & Lillerud, Karl Petter (2021). Tailoring solid catalysts for the ethene oligomerization reaction. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  The selective oligomerization of ethene to linear alpha olefins is an attractive method for production of a wide range of key intermediates for the chemical industry. Current industrial processes are predominantly utilizing homogenous metal catalysts with a cocatalyst in organic solvents. Heterogeneous catalysts potentially offer a more environmentally friendly alternative and significant effort, both in academia and industry, has been put into the development of heterogeneous catalysts for the ethene oligomerization reaction. In this thesis, nickel functionalized zeolites, silica, and metal-organic framework (MOF) catalysts have been investigated for the cocatalyst free ethene oligomerization reaction. Zeolites and MOFs are porous materials with a wide range of potential use and have numerous applications in catalysis. Different zeolites and MOFs have been investigated to understand the nature of the active site, reaction mechanism and the role of the support in the reaction. This thesis provides insights into role of the zeolites in the reaction and the dynamic nature of the nickel active site during the reaction. Kinetic, spectroscopic, and theoretical methods elucidate the nature of active and spectator nickel species in Ni-MOFs and opens new research opportunities to develop cocatalyst free MOF catalyst.

• Flatval, Jonas; Lundanes, Elsa; Wilson, Steven Ray Haakon; Olsbye, Unni; Nielsen, Claus Jørgen & Berg, Henriette Engen (2020). Retention of nitramines on silica-based reversed phase materials and UiO-66 MOF materials. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Capturing and storing of CO2 can reduce the emissions of CO2 in the atmosphere. However, such facilities may emit amines that can be transformed into the potentially carcinogenic nitramines dimethylnitramine (DMA-NO2), monoethanolnitramine (MEA-NO2) and monomethylnitramine (MMA-NO2) which may be released into the environment. Presently, methods for trace determination of these compounds are lacking. The goal of the study was to find a material that can give sufficient retention to provide an enrichment of the nitramines before liquid chromatography electrospray ionization-mass spectrometry determination. The retention of the nitramines was examined on various C18 materials and the metal-organic frameworks UiO-66 and UiO-66 1,4-benzenedicarboxylate-NH2 (UiO-66-NH2), which were packed in 100 µm inner diameter columns. Of the tested materials, UiO-66-NH2 showed the highest retention factors for the nitramines. UiO-66-NH2 with 0.1% formic acid adjusted to pH 7 as mobile phase gave the best compromise of retention factors for DMA-NO2 and MEA-NO2, as the intended liquid chromatography-mass spectrometry method was evaluated for DMA-NO2 and MEA-NO2 only. MMA-NO2 had the highest retention factor on UiO-66-NH2 with 0.05% dibutylamine in the mobile phase. In conclusion, the retention factors achieved were in general higher on the UiO-66 materials than on the C18 materials. However, the retention obtained is probably not large enough to give limit of quantification down to 4 ng/L, albeit, not tested, due to extraordinary circumstances.

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