bjorngso

• 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.

• 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.

• 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).

• 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.

• 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.

• Deplano, Gabriele; Signorile, Matteo; Crocellà, Valentina; Porcaro, Natale Gabriele; Atzori, Cesare & Solemsli, Bjørn Gading [Vis alle 8 forfattere av denne artikkelen] (2022). Titration of Cu(I) Sites in Cu-ZSM-5 by Volumetric CO Adsorption. ACS Applied Materials & Interfaces. ISSN 1944-8244. 14(18), s. 21059–21068. doi: 10.1021/acsami.2c03370. Fulltekst i vitenarkiv Vis sammendrag

  Cu-exchanged zeolites are widely studied materials because of their importance in industrial energetic and environmental processes. Cu redox speciation lies at the center of many of these processes but is experimentally difficult to investigate in a quantitative manner with regular laboratory equipment. This work presents a novel technique for this purpose that exploits the selective adsorption of CO over accessible Cu(I) sites to quantify them. In particular, isothermal volumetric adsorption measurements are performed at 50 °C on a series of opportunely pre-reduced Cu-ZSM-5 to assess the relative fraction of Cu(I); the setup is fairly simple and only requires a regular volumetric adsorption apparatus to perform the actual measurement. Repeatability tests are carried out on the measurement and activation protocols to assess the precision of the technique, and the relative standard deviation (RSD) obtained is less than 5%. Based on the results obtained for these materials, the same CO adsorption protocol is studied for the sample using infrared spectroscopy, and a good correlation is found between the results of the volumetric measurements and the absorbance of the peak assigned to the Cu(I)–CO adducts. A linear model is built for this correlation, and the molar attenuation coefficient is obtained, allowing for spectrophotometric quantification. The good sensitivity of the spectrophotometric approach and the precision and simplicity of the volumetric approach form a complementary set of tools to quantitatively study Cu redox speciation in these materials at the laboratory scale, allowing for a wide range of Cu compositions to be accurately investigated.

• Gutterød, Emil Sebastian; Pulumati, S.H.; Kaur, Gurpreet; Lazzarini, Andrea; Solemsli, Bjørn Garding & Gunnæs, Anette Eleonora [Vis alle 13 forfattere av denne artikkelen] (2020). Influence of Defects and H2O on the Hydrogenation of CO2 to Methanol over Pt Nanoparticles in UiO-67 Metal-Organic Framework. Journal of the American Chemical Society. ISSN 0002-7863. 142(40), s. 17105–17118. doi: 10.1021/jacs.0c07153. Fulltekst i vitenarkiv Vis sammendrag

  In catalysts for CO2 hydrogenation, the interface between metal nanoparticles (NPs) and the support material is of high importance for the activity and reaction selectivity. In Pt NP-containing UiO Zr-metal–organic frameworks (MOFs), key intermediates in methanol formation are adsorbed at open Zr-sites at the Pt–MOF interface. In this study, we investigate the dynamic role of the Zr-node and the influence of H2O on the CO2 hydrogenation reaction at 170 °C, through steady state and transient isotope exchange experiments, H2O cofeed measurements, and density functional theory (DFT) calculations. The study revealed that an increased number of Zr-node defects increase the formation rates to both methanol and methane. Transient experiments linked the increase to a higher number of surface intermediates for both products. Experiments involving either dehydrated or prehydrated Zr-nodes showed higher methanol and methane formation rates over the dehydrated Zr-node. Transient experiments suggested that the difference is related to competitive adsorption between methanol and water. DFT calculations and microkinetic modeling support this conclusion and give further insight into the equilibria involved in the competitive adsorption process. The calculations revealed weaker adsorption of methanol in defective or dehydrated nodes, in agreement with the larger gas phase concentration of methanol observed experimentally. The microkinetic model shows that [Zr2(μ-O)2]4+ and [Zr2(μ–OH)(μ-O)(OH)(H2O)]4+ are the main surface species when the concentration of water is lower than the number of defect sites. Lastly, although addition of water was found to promote methanol desorption, water does not change the methanol steady state reaction rate, while it has a substantial inhibiting effect on CH4 formation. These results indicate that water can be used to increase the reaction selectivity to methanol and encourages further detailed investigations of the catalyst system.

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• Solemsli, Bjørn Gading; Svelle, Stian; Prodinger, Sebastian & Kvande, Karoline (2022). Methylation of Lower alkenes though stepwise reaction with methane. Fulltekst i vitenarkiv
• Solemsli, Bjørn Gading; Kvande, Karoline; Prodinger, Sebastian & Svelle, Stian (2022). Fuels & Chemicals from Methane. Fulltekst i vitenarkiv
• Solemsli, Bjørn Gading; Svelle, Stian; Kvande, Karoline & Prodinger, Sebastian (2022). Direct Synthesis to Methanol from Methane over Cu-Zeolites. Fulltekst i vitenarkiv
• Kvande, Karoline; Prodinger, Sebastian; Borfecchia, Elisa; Garetto, Beatrice; Solemsli, Bjørn Gading & Signorile, Matteo [Vis alle 10 forfattere av denne artikkelen] (2022). Structural and mechanistic investigations of CuxOy- sites in zeolites and their role in the direct activation of lower alkanes. Fulltekst i vitenarkiv
• Solemsli, Bjørn Gading; Olsbye, Unni; Gunnæs, Anette Eleonora & Gutterød, Emil Sebastian (2020). A Study of Catalytic Pt Nanoparticles inside a Nano-porous Functionalized UiO MOF-matrix for CO2-Hydrogenation. Universitetet i Oslo. Fulltekst i vitenarkiv

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