02473nas a2200265   4500008004100000022001400041245008800055210006900143260000800212300001600220490000600236520163300242653001701875653001801892653003101910653002501941100001801966700001901984700001802003700002002021700002402041700001602065700001802081856010802099       2019                        eng d  a2168-048500aMechanistic insights into the pathways of phenol hydrogenation on Pd nanostructures0 aMechanistic insights into the pathways of phenol hydrogenation o  cOCT  a17126-171360 v73 a<p>Product selectivity in aqueous phase phenol hydrogenation on well-defined supported Pd nanostructures (spheres, cubes, and octahedra) was studied using defined experiments and density functional theory (DFT) simulations. On Pd spheres and octahedra, the reaction initially showed high selectivity (in the first 3 h, at 363 K and 5 bar H-2 pressure) toward the partially hydrogenated product cyclohexanone. On prolonged operation (&gt;20 h of reaction time), a shift in the product selectivity (up to 100%) toward the completely hydrogenated product cyclohexanol was observed on Pd spheres and octahedra. In contrast, the reaction on Pd cubes, which only had {100} facets, showed a high selectivity (similar to 90%) toward the product cyclohexanone even after 40 h, at the same reaction conditions. Since the {111} facets are expected to be the majority sites on a spherical particle, we attribute the selectivity trend observed on spherical Pd particles to be primarily controlled by the selectivity trend on the Pd{111} facets. This observation was further confirmed on performing the hydrogenation reaction on a mixture of Pd cube and Pd octahedron particles in a ratio of 25:75 (representing the site ratio of a spherical particle). DFT simulations provided a mechanistic insight into the reactivity of the two different facets ({100} and {111}) toward phenol hydrogenation. The calculations revealed that the selectivity significantly depended on the activation barriers involved in cyclohexanone hydrogenation on the Pd{111} facets (77 and 57 kJ/mol) as compared to those on the Pd{100} facets (97 and 101 kJ/mol).</p>
10aCyclohexanol10acyclohexanone10afacet-dependent reactivity10aphenol hydrogenation1 aPorwa, Govind1 aGupta, Shelaka1 aSreedhala, S.1 aElizabeth, Joes1 aIthan, Tuhin, Suvra1 aHaider, Ali1 aVinod, C., P.  uhttps://library.ncl.res.in/content/mechanistic-insights-pathways-phenol-hydrogenation-pd-nanostructures01974nas a2200241   4500008004100000245014200041210006900183260000800252300001600260490000600276520110900282653001801391653001801409653002801427653003701455653002501492100001801517700001901535700001701554700001701571700001801588856012601606       2023                        eng d00aPd nanoparticles supported on N-incorporated hybrid organosilica as an active and selective low-temperature phenol hydrogenation catalyst0 aPd nanoparticles supported on Nincorporated hybrid organosilica   cJUN  a11500-115120 v63 a<p>
	A heterogeneous Pd-NPMO hybrid-silicacatalyst is synthesized andits application for aqueous phase selective hydrogenation of phenolto cyclohexanone at near ambient temperature (40 degrees C) and underatmospheric hydrogen pressure is demonstrated. The homogeneously distributedPd nanoparticles on N-bridged hybrid mesoporous organosilica showedremarkable activity and selectivity for cyclohexanone compared tothe unmodified Pd-SBA-15 catalyst. Control experiments strongly claimthe role of nitrogen domains in the organic framework of hybrid silicasupport in stabilizing small Pd nanoparticles and possibly modifyingthe Pd sites responsible for catalysis to activate the substrate moleculesin water. The hybrid silica catalyst was stable and reused severaltimes without any significant drop-in activity, proving the heterogeneityof the bifunctional Pd catalyst. Based on the density functional theorystudy and experimental interventions, a possible reaction mechanismfor the low-temperature phenol hydrogenation explaining the role oforganic domains in the hybrid-silica framework is proposed.</p>
10acyclohexanone10aHybrid silica10apalladium nanoparticles10aPeriodic mesoporous organosilica10aphenol hydrogenation1 aBetsy, K., J.1 aBajpai, Priyam1 aLazar, Anish1 aVanka, Kumar1 aVinod, C., P.  uhttps://library.ncl.res.in/content/pd-nanoparticles-supported-n-incorporated-hybrid-organosilica-active-and-selective-low