Novel nano-semiconductor film layer supported nano-Pd Complex Nanostructured Catalyst Pd/Ⓕ-MeOx/AC for High Efficient Selective Hydrogenation of Phenol to Cyclohexanone
Supported metal as a type of heterogeneous catalysts are the most widely used in industrial processes. High dispersion of the metal particles of supported catalyst is a key factor in determining the performance of such catalysts. Here we report a novel catalyst Pd/Ⓕ-MeOx/AC with complex nanostructured, Pd nanoparticles supported on the platelike nano-semiconductor film/activated carbon, prepared by the photocatalytic reduction method, which exhibited high efficient catalytic performance for selective hydrogenation of phenol to cyclohexanone. Conversion of phenol achieved up to more than 99% with a lower mole ratio (0.5%) of active components Pd and phenol within 2 h at 70 °C. The synergistic effect of metal nanoparticles and nano-semiconductors support layer and the greatly increasing of contact interface of nano-metal-semiconductors may be responsible for the high efficiency. This work provides a clear demonstration that complex nanostructured catalysts with nano-metal and nano-semiconductor film layer supported on high specific surface AC can yield enhanced catalytic activity and can afford promising approach for developing new supported catalyst.
Tuning surface properties of N-doped carbon with TiO2 nano-islands for enhanced phenol hydrogenation to cyclohexanone
Abstract ZIF-derived N-doped carbon (CN) materials were modified in this work by TiO2 nano-islands with oxygen vacancies (OV) through a sol-gel method and subsequent thermal treatment. By loading Pd nanoparticles (NPs) on CN@TiO2, Pd@CN@TiO2 catalysts were fabricated. Superior catalytic performance of Pd@CN@TiO2 was found in the selective phenol hydrogenation to cyclohexanone, with a TOF of 30.1 h−1, 2.2-fold as high as that of Pd@CN. The synergistic effect of CN and TiO2 nano-islands was responsible for the superior catalytic performance. More OV was generated due to the high specific surface area of CN. At the same time, CN could also enhance the hydrophilicity, and adsorb more phenol in non-planar fashion. The TiO2 nano-islands with OV could improve the Pd dispersion, make more Pd element on the support surface, strengthen the antioxidizability of Pd and induce electron-rich Pd NPs. Furthermore, the as-fabricated Pd@CN@TiO2 showed good recyclability in the phenol hydrogenation, and also exhibited excellent catalytic performance in the catalytic hydrogenation of phenol with diverse functional groups. These findings provide the feasibility of using the high-performance catalysts for the hydrogenation of phenol derivatives.
Gas-Phase Oxidative Dehydrogenation of Cyclohexanol over ETS-10 and Related Materials
Abstract The gas-phase oxidative dehydrogenation of cyclohexanol with air using ETS-10 and related materials is studied. At reaction temperatures below 200°C, ETS-10 was 100% selective to cyclohexanone and 75% cyclohexanol conversion was achieved. Catalyst deactivation was attributed to pore blockage. The catalyst is completely regenerated by calcination at 400°C. Cyclohexanol conversion increases with temperature and oxygen/cyclohexanol feed ratios. The introduction of Cr, Fe, K, or Cs in ETS-10 affects stability and decreases conversion and selectivity towards cyclohexanone. For comparison, some results on TS-1, zeolites NaX, and mordenite are also presented.