@article {46688, title = {CO2 hydrogenation to formate by palladium nanoparticles supported on N-incorporated periodic mesoporous organosilica}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {8}, year = {2020}, month = {OCT }, pages = {14765-14774}, type = {Article}, abstract = {

Development of a heterogeneous catalyst capable of selective transformation of CO2 to valuable products still remains a challenge. In this article, we account for the surfactant-directed synthesis of a new framework-incorporated nitrogen-containing periodic mesoporous organosilica nanosphere (NPMO). A thoroughly characterized N-incorporated hybrid PMO was utilized as a platform for stabilizing well-dispersed and easily accessible Pd nanoparticles (Pd-NPMO) without using any stabilizing agents or expensive dendrimers. Further, this bifunctional hybrid catalyst has been demonstrated to heterogeneously catalyze aqueous phase CO2 hydrogenation (CO2/H-2 ratio 1:3) for the direct synthesis of formate under 4 MPa pressure and at 100 degrees C. To validate the superior performance of the Pd-NPMO catalyst, we compared the activity with Pd-SBA-15 catalysts, and the results showed a 10-fold increase in turnover frequency of 108 h(-1) using Pd on NPMO which envisaged the crucial role of nitrogen sites in this catalyst to boost the CO2 valorization to formate.

}, keywords = {CO2 hydrogenation, Formic acid synthesis, Hybrid silica, Pd nanoparticles, PMO}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.0c03860}, author = {Betsy, K. J. and Lazar, Anish and Pavithran, Anjuna and Vinod, C. P.} } @article {46837, title = {Engineering pore morphology using silica template route over mesoporous cobalt oxide and its implications in atmospheric pressure carbon dioxide hydrogenation to olefins}, volume = {19}, year = {2020}, month = {JUN}, pages = {100586}, type = {Article}, abstract = {

Highly ordered mesoporous cobalt oxides (denoted as m-Co-KIT-6 and m-Co-SBA-15) with three dimensional and two dimensional pore morphology respectively have been synthesized using 3D KIT-6, and 2D SBA-15 as silica template via nanocasting route. CO2 hydrogenation activity was evaluated for these mesoporous materials under atmospheric pressure conditions. In comparison to nanoparticles of cobalt oxide (Co3O4-nano), mesoporous catalysts showed excellent activity for CO2 hydrogenation due to their higher number of exposed active sites and lower mass diffusion limitations. The ordered mesoporous structure of Co3O4 catalysts favored the chain growth of carbon atoms for the production of C2+ hydrocarbons while Co3O4 nanoparticles showed strong selectivity toward CH4. High selectivity for C2+ (similar to 25\%) was obtained for both m-Co-KIT-6 and m-Co-SBA-15 catalysts at 320 degrees C. In addition, the 3D pore structure of m-Co-KIT-6 catalyst exclusively formed more olefins (54.9\%) fraction. (C) 2020 Published by Elsevier Ltd.

}, keywords = {CO2 hydrogenation, Mesoporous CO3O4, Olefin fraction, Pore morphology, Silica hard template}, issn = {2352-9407}, doi = {10.1016/j.apmt.2020.100586}, author = {Gupta, Sharad and Ciotonea, Carmen and Royer, Sebastien and Dacquin, Jean-Philippe and Vinod, C. P.} } @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 {47634, title = {Role of metal-support interaction for atmospheric pressure CO2 hydrogenation over Pd/(Ti)-SBA-15 catalyst: effect of titanium composition on products selectivity}, journal = {Molecular Catalysis}, volume = {511}, year = {2021}, month = {JUL}, pages = {111732}, type = {Article}, abstract = {The potential role of metal-support interaction for tuning the product selectivity during atmospheric pressure CO2 hydrogenation has been demonstrated on Pd/(Ti)-SBA-15 catalyst. Highly dispersed Pd NPs on SBA-15 (Pd/ SBA-15) was synthesized and further modified with titanium of varying composition. Comparison of catalytic activity of Pd/Ti-SBA-15 with its counterparts (Pd/SBA-15 and Pd/TiO2) illustrated the significance of strong PdTi interface in this catalyst and its role in tuning the product selectivity of CO2 hydrogenation. The generation of an ample amount of oxygen vacancies in the Pd/Ti-SBA-15 catalyst with maximum metallic Pd sites in close vicinity of Ti is proposed to boost the CO2 hydrogenation activity.}, keywords = {CO2 hydrogenation, Metal-support interaction, Modified deposition precipitation, oxygen vacancies, Titanosilicates}, issn = {2468-8231}, doi = {10.1016/j.mcat.2021.111732}, author = {Soni, Yogita and Gupta, Sharad and Vinod, C. P.} } @article {49035, title = {Exploring the catalytic potential of Mg-Cu alloys for enhanced activity toward CO2 hydrogenation}, journal = {Molecular Catalysis }, volume = {556}, year = {2024}, month = {MAR }, type = {Article}, abstract = {

CO2, a well-known greenhouse gas, is a potential raw material that can produce various chemicals. Dissociation of CO2 to CO or hydrogenation to formate (HCOO*) or carboxyl (COOH*) intermediate is crucial in determining the reaction pathway for CO2 conversion. In this work, we demonstrate that alloys of Mg-Cu exhibit greater activity toward activation and hydrogenation of CO2 than transition metal alloys reported so far. Two different compositions of Mg-Cu, namely Mg2Cu and MgCu2, have been studied using periodic Density Functional Theory (DFT). Our investigations reveal that CO2 chemisorbs on both intermetallic alloys. Coadsorption of CO2 with H2O leads to the spontaneous formation of COOH* over Mg2Cu(224), whereas a negligible barrier (0.04 eV) is observed for MgCu2(311). HCOO* formation has a barrier of 0.34 eV and 0.42 eV on Mg2Cu(224) and MgCu2(311), respectively. Dissociation of CO2 to CO is kinetically unfavourable on both compositions of Mg-Cu. We provide a rationale for the observed activity by analyzing the electronic structure. Notably, the spontaneous hydrogenation of CO2 makes earth -abundant metals suitable candidates for alloying that await experimental verification.

}, keywords = {CO2 hydrogenation, DFT, Mg2Cu, MgCu2}, issn = {2468-8231}, doi = {10.1016/j.mcat.2024.113839}, author = {Thakkar, Kavita and Joshi, Kavita} } @article {49352, title = {Size and morphology dependent activity of Cu clusters for CO2 activation and reduction: a first principles investigation}, journal = {ChemPhysChem}, volume = {25}, year = {2024}, month = {DEC}, type = {Article}, abstract = {

Various Cu-based materials in diverse forms have been investigated as efficient catalysts for electrochemical reduction of CO2; however, they suffer from issues such as higher over potential and poor selectivity. The activity and selectivity of CO2 electro reduction have been shown to change significantly when the surface morphology (steps, kinks, and edges) of these catalysts is altered. In light of this, size and morphology dependent activity of selected copper clusters, Cun (n=2-20) have been evaluated for the activation and reduction of CO2 molecule. The phase-space of these copper clusters is rich in conformations of distinct morphologies starting from planar, 2D geometries to prolate-shaped geometries and also high-symmetry structures. The binding efficiency and the activation of CO2 are highest for medium sized clusters (n=9-17) with prolate-morphologies as compared to small or larger sized CunCO(2) clusters that are existing mainly as planar (triangular, tetragonal etc.) or highly-symmetric geometries (icosahedron, capped-icosahedron etc.), respectively. The best performing (prolate-shaped) CunCO2 conformations are quite fluxional and also they are thermally stable, as demonstrated by the molecular dynamics simulations. Furthermore, on these CunCO(2) conformations, the step-by-step hydrogenation pathways of CO2 to produce value-added products like methanol, formic acid, and methane are exceptionally favorable and energy-efficient.

}, keywords = {CO2 activation, CO2 hydrogenation, Copper clusters, Density Functional Theory (DFT), molecular dynamics}, issn = {1439-4235}, doi = {10.1002/cphc.202400442}, author = {Amin, Seerat and Krishnamurty, Sailaja and Dar, Manzoor Ahmad and Joshi, Krati} }