Karoline Kvande

• Kvande, Karoline; Pappas, Dimitrios; Borfecchia, Elisa & Lomachenko, Kirill A. (2020). Advanced X‐ray Absorption Spectroscopy Analysis to Determine Structure‐Activity Relationships for Cu‐Zeolites in the Direct Conversion of Methane to Methanol. ChemCatChem.  ISSN 1867-3880.  12, s 2385- 2405 . doi: 10.1002/cctc.201902371
• Kvande, Karoline; Pappas, Dimitrios; Dyballa, Michael Martin; Buono, Carlo; Signorile, Matteo; Borfecchia, Elisa; Lomachenko, Kirill A.; Arstad, Bjørnar; Bordiga, Silvia; Berlier, Gloria; Olsbye, Unni; Beato, Pablo & Svelle, Stian (2020). Comparing the Nature of Active Sites in Cu-loaded SAPO-34 and SSZ-13 for the Direct Conversion of Methane to Methanol. Catalysts.  ISSN 2073-4344.  10(191) . doi: 10.3390/catal10020191 Fulltekst i vitenarkiv. Vis sammendrag

  On our route towards a more sustainable future, the use of stranded and underutilized natural gas to produce chemicals would be a great aid in mitigating climate change, due to the reduced CO2 emissions in comparison to using petroleum. In this study, we investigate the performance of Cu-exchanged SSZ-13 and SAPO-34 microporous materials in the stepwise, direct conversion of methane to methanol. With the use of X-ray absorption spectroscopy, infrared (in combination with CO adsorption) and Raman spectroscopy, we compared the structure–activity relationships for the two materials. We found that SSZ-13 performed significantly better than SAPO-34 at the standard conditions. From CH4-TPR, it is evident that SAPO-34 requires a higher temperature for CH4 oxidation, and by changing the CH4 loading temperature from 200 to 300 ◦C, the yield (µmol/g) of SAPO-34 was increased tenfold. As observed from spectroscopy, both three- and four-fold coordinated Cu-species were formed after O2-activation; among them, the active species for methane activation. The Cu speciation in SAPO-34 is distinct from that in SSZ-13. These deviations can be attributed to several factors, including the different framework polarities, and the amount and distribution of ion exchange sites.

• Martini, Andrea; Signorile, Matteo; Negri, Chiara; Kvande, Karoline; Lomachenko, Kirill A.; Svelle, Stian; Beato, Pablo; Berlier, Gloria; Borfecchia, Elisa & Bordiga, Silvia (2020). EXAFS wavelet transform analysis of Cu-MOR zeolites for the direct methane to methanol conversion. Physical Chemistry, Chemical Physics - PCCP.  ISSN 1463-9076.  22, s 18950- 18963 . doi: 10.1039/D0CP01257B
• Pappas, Dimitrios; Kvande, Karoline; Kalyva, Maria Evangelou; Dyballa, Michael Martin; Lomachenko, Kirill A.; Arstad, Bjørnar; Borfecchia, Elisa; Bordiga, Silvia; Olsbye, Unni; Beato, Pablo & Svelle, Stian (2020). Influence of Cu-speciation in mordenite on direct methane to methanol conversion: Multi-Technique characterization and comparison with NH3 selective catalytic reduction of NOx. Catalysis Today.  ISSN 0920-5861.  s 1- 7 . doi: 10.1016/j.cattod.2020.06.050 Fulltekst i vitenarkiv. Vis sammendrag

  The direct conversion of methane to methanol has the potential of substantially reducing methane emissions and flaring, as such a process might provide an alternative for remote natural gas locations. In this report, we investigate the performance of a range of Cu-exchanged mordenite zeolites as active materials for such a reaction, employing a stepwise protocol comprising activation in oxygen, methane loading, and methanol extraction with steam. We employ in situ HERFD XANES, FT-IR spectroscopy with CO as probe molecule, and XPS to investigate the Cu species in the zeolites during the process. The activity of the materials is investigated both for methane to methanol conversion and NH3 Selective Catalytic Reduction of NOx. It is demonstrated that, despite the fact that the same zeolite materials are active both for NH3-SCR and direct methane to methanol conversion, the active site requirements for these two reactions are different.

• Dyballa, Michael Martin; Thorshaug, Knut; Pappas, Dimitrios; Borfecchia, Elisa; Kvande, Karoline; Bordiga, Silvia; Berlier, Gloria; Lazzarini, Andrea; Olsbye, Unni; Beato, Pablo; Svelle, Stian & Arstad, Bjørnar (2019). Zeolite surface methoxy groups as key intermediates in the stepwise conversion of methane to methanol. ChemCatChem.  ISSN 1867-3880.  11(20), s 5022- 5026 . doi: 10.1002/cctc.201901315 Fulltekst i vitenarkiv. Vis sammendrag

  This contribution clarifies the overoxidation-preventing key step in the methane-to-methanol (MTM) conversion over copper mordenite zeolites. We followed the methane-to-methanol conversion over copper mordenite zeolites by NMR spectroscopy supported by DRIFTS to show that surface methoxy groups (SMGs) located at zeolite Brønsted sites are the key intermediates. The SMGs with chemical shift of 59 ppm are identical to those formed on a copper-free reference zeolite after reaction with methanol and react with water, methanol, or carbon monoxide to yield methanol, dimethyl ether, and acetate. This reactivity corroborates the location of SMGs at Brønsted sites. We find no evidence for stable SMGs directly at copper sites and explain mechanistically why H-form mordenites outperform their Na-form analogues. This finding is of interest for any future process that tries to trap the intermediate methane oxidation product towards methanol.

• Dyballa, Michael Martin; Pappas, Dimitrios; Kvande, Karoline; Borfecchia, Elisa; Arstad, Bjørnar; Beato, Pablo; Olsbye, Unni & Svelle, Stian (2019). On how copper mordenite properties govern the framework stability and activity in the methane-to-methanol conversion. ACS Catalysis.  ISSN 2155-5435.  9(1), s 365- 375 . doi: 10.1021/acscatal.8b04437
• Buono, Carlo; Martini, Andrea; Pankin, Ilya; Pappas, Dimitrios; Negri, Chiara; Kvande, Karoline; Lomachenko, Kirill A. & Borfecchia, Elisa (2018). Local structure of Cu(I) ions in the MOR zeolite: A DFT-assisted XAS study. Radiation Physics and Chemistry.  ISSN 0969-806X. . doi: 10.1016/j.radphyschem.2018.12.031
• Pappas, Dimitrios; Martini, Andrea; Dyballa, Michael Martin; Kvande, Karoline; Teketel, Shewangizaw; Lomachenko, Kirill A.; Baran, Rafal; Glatzel, Pieter; Arstad, Bjørnar; Berlier, Gloria; Lamberti, Carlo; Bordiga, Silvia; Olsbye, Unni; Svelle, Stian; Beato, Pablo & Borfecchia, Elisa (2018). The nuclearity of the active site for methane to methanol conversion in Cu-mordenite: a quantitative assessment. Journal of the American Chemical Society.  ISSN 0002-7863.  140(45), s 15270- 15278 . doi: 10.1021/jacs.8b08071 Fulltekst i vitenarkiv.

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• Arstad, Bjørnar; Dyballa, Michael Martin; Thorshaug, Knut; Pappas, Dimitrios K; Borfecchia, Elisa; Kvande, Karoline; Bordiga, Silvia; Berlier, Gloria; Lazzarini, Andrea; Olsbye, Unni; Beato, Pablo & Svelle, Stian (2020). Solid State NMR studies of the stepwise transformation of methane to methanol over Cu-Zeolites.
• Kvande, Karoline & Svelle, Stian (2020). New paths for “direct activation of lower alcanes”.
• Kvande, Karoline; Svelle, Stian & Beato, Pablo (2020). CH4-TPR: A good descriptor for optimizing the direct conversion of methane-to-methanol?.
• Dyballa, Michael Martin; Pappas, Dimitrios; Borfecchia, Elisa; Kvande, Karoline; Bordiga, Silvia; Berlier, Gloria; Lamberti, Carlo; Arstad, Bjørnar; Beato, Pablo; Olsbye, Unni & Svelle, Stian (2019). Cu-MOR applied in the stepwise methane-to-methanol conversion.
• Kvande, Karoline (2019). Comparing the Nature of the Active Sites in Cu-loaded SAPO-34 and SSZ-13 for the Direct Conversion of Methane to Methanol.
• Kvande, Karoline (2019). DIRECT CONVERSION OF METHANE TO METHANOL - A more Sustainable Solution.
• Kvande, Karoline (2019). Direct methane to methanol conversion: comparing the activity of Cu-SAPO-34 and Cu-SSZ-13.
• Kvande, Karoline; Svelle, Stian; Dyballa, Michael Martin & Pappas, Dimitrios (2019). A Study of Cu-loaded SAPO-34 for the Direct Conversion of Methane to Methanol.
• Kvande, Karoline (2017). Direct conversion of methane to methanol.

Se alle arbeider i Cristin