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.
Vapor phase hydrogenation of phenol over silica supported Pd and PdYb catalysts
Abstract The catalytic activity/selectivity of a 5% w/w Pd/SiO 2 catalyst prepared by Pd(NO 3 ) 2 impregnation has been compared with that delivered by 5% w/w Pd/SiO 2 and PdYb/SiO 2 prepared from Pd(C 2 H 3 O 2 ) 2 and {(DMF) 10 Yb 2 [Pd(CN) 4 ] 3 } ∞ precursors, respectively; phenol hydrogenation (T=423 K ) was used as a test reaction. The activated catalysts have been characterized by HRTEM/EDX; differences in activity are related to the TEM derived Pd particle size distribution. Incorporation of Yb resulted in an appreciable enhancement of both phenol conversion and the overall yield of cyclohexanone, an effect that is attributed to electron donation from Yb to the active Pd centers.
DRIFT study of CO chemisorption on organometallics-derived Pd/MgO catalysts: the effect of chlorine
Magnesia-supported palladium catalysts were prepared from chemical vapour deposition (CVD) of [Pd(C3H5)(C5H5)] and incipient wetness impregnation of [Pd(C3H5)Cl]2 and [Pd(acac)2]. DRIFT spectroscopy of adsorbed CO on prereduced catalysts indicates that the electronic state of metal particles depends on the preparation methodology and markedly on the organometallic precursor. Inn-heptane reforming at 500°C, the highest activity and selectivity were shown by the CVD-based system. Chloride ions deriving from the impregnation solvent exchange with surface hydroxyls. Acidic Mg-Cl sites are thus formed, which induce a beneficial effect on the catalytic properties. The reforming activity collapsed when a chlorine-containing precursor was used, due to a partial coverage of the palladium surface with chemisorbed chlorine atoms.