@article {46978, title = {Variations in activity of Ru/TiO(2 )and Ru/Al2O3 catalysts for CO2 hydrogenation: an investigation by in-situ infrared spectroscopy studies}, journal = {Molecular Catalysis}, volume = {482}, year = {2020}, month = {FEB}, pages = {110700}, type = {Article}, abstract = {

CO2 hydrogenation to methane, an important reaction strategically and also for value adding to CO2, is investigated on two different catalysts, Ru supported on alumina as well as titania to understand better low temperature activity of Ru/TiO2 catalyst. In-situ infrared studies are carried out in three different steps, viz., (i) CO2 adsorption on fully reduced catalyst (ii) reaction of these adsorbed species with gaseous H-2 and (iii) under co-feed of CO2 and H-2, at different temperatures. On Ru/Al2O3 catalyst, CO2 reacts with hydroxyls on the support surface to form carbonate and adsorbs reductively on metal as CO. Further reduction to formate and methyl species occurs on reaction with H. Small concentration of the reactive intermediate formyl forms only at high temperatures. Whereas, bare TiO2 itself seems capable of reductive adsorption of CO2 as formate indicating enhanced reducibility of titania based catalyst. Formyl groups are observed at low temperatures in Ru/TiO2 in step (ii), which further forms methyl and gaseous methane at much lower temperatures when compared to alumina catalyst. Highly reactive CO species loosely bound to metal-support interface observed at high temperatures, which is not present on Ru/Al2O3 catalyst also makes this catalyst superior. In comparison, linearly bound CO seen in alumina catalyst is not as reactive.

}, keywords = {CO2 hydrogenation, In-situ infra red spectroscopy, Ru/Al2O3, Ru/TiO2}, issn = {2468-8231}, doi = {10.1016/j.mcat.2019.110700}, author = {Dongapure, Pavan and Bagchi, Sayan and Mayadevi, S. and Devi, R. Nandini} } @article {48012, title = {Effect of B site substitution in Gd2B2-xNiyO7-delta (B= Ti, Zr) ternary metal oxide catalysts in dry reforming of methane}, journal = {Molecular Catalysis}, volume = {522}, year = {2022}, month = {APR}, pages = {112242}, type = {Article}, abstract = {

Structured catalysts are emerging as active and durable catalysts in dry reforming of methane due to their inherent characteristics like lattice insertion of active metals and consequent stability imparted. Here we report Ti and Zr substituted Gd2B2-xNiyO7-delta (B = Ti, Zr) catalysts synthesized by citrate gel method, which are characterized and tested for dry reforming of methane. Structure and Ni substitution has been confirmed by Rietveld refinement of powder XRD patterns and Raman analysis. TPR and CO2-TPD were performed to analyze the reducibility and effect of basic sites of catalysts in DRM activity. Ni doped Ti analogue shows stable and superior activity towards dry reforming of methane for 100 h. The in situ IR studies and XPS analysis confirmed the presence of surface hydroxyl species in this catalyst, which triggers the activation of CO2 and provides higher and durable activity in dry reforming reaction. Absence of any C formation in this catalyst after durability test indicates the mechanism of C gasification by the surface hydroxyl species enhancing stable activity for long durations.

}, keywords = {A(2)B(2)O(7), Citrate gel method, Dry reforming of methane, Ternary metal oxide}, issn = {2468-8231}, doi = {10.1016/j.mcat.2022.112242}, author = {Ghodke, Seema R. and Thundiyil, Shibin and Dongapure, Pavan and Devi, R. Nandini} } @article {48756, title = {Mechanistic insights into near ambient pressure activity of intermetallic NiZn/TiO2 catalyst for CO2 conversion to methanol}, journal = {ChemCatChem}, volume = {15}, year = {2023}, month = {JAN }, type = {Article}, abstract = {

Ni-Zn pair is predicted through descriptor-based studies to be conducive for CO2 hydrogenation. In this study, NiZn (1 : 1) intermetallics supported on TiO2 is identified as a potential candidate for near ambient pressure activity. The effect of reduction temperature on the catalyst textural properties as well as on CO2 to methanol reduction are explored. Structural and microscopic studies provide clear evidence of phase evolution of NiZn alloy with increasing reduction temperatures, along with phase variations of Zn based oxides. Interface between NiZn intermetallics and ZnO nanoparticles observed at reduction temperature of 550 degrees C, seems to play a crucial role in making this system most active and selective to methanol. In addition, in-situ IR studies provide mechanistic insights and indicates the formation of methanolic species even at ambient pressure.

}, keywords = {CCUS, CO2, In-situ IR, Methanol, near ambient pressure}, issn = {1867-3880}, doi = {10.1002/cctc.202201150}, author = {Dongapure, Pavan and Tekawadia, Jyoti and Thundiyil, Shibin and Caha, Ihsan and Deepak, Francis Leonard and Devi, R. Nandini} }