介孔 γ-Al₂O₃微球的高效制备及负载Pd 催化剂的性能

Porous γ-Al₂O₃ has been widely used as the support material due to its ultrahigh specific surface area，strong adsorption capacity and great thermal stability. However，owing to a series of problems existing in the synthesis process of porous γ-Al₂O₃ materials，like complex preparation method，high energy consumption，low purity and serious environmental pollution，it is important to develop a synthesis method of high-purity porous γ-Al₂O₃ catalyst possessing high efficiency with abundant pore structures. In this paper，based on the chemistry of hydrolysis conden⁃ sation reaction of aluminum alkoxide，mesoporous γ-Al₂O₃ microspheres with high surface area，pore volume and purity were synthesized under normal temperature and pressure conditions，and the influences of additive dosage，reaction temperature，post-treatment drying temperature and other factors on the pore structure and morphology of γ-Al₂O₃ were also systematically studied. In the same breath，the supported mesoporous Pd/γ-Al₂O₃ microsphere catalytic material with highly dispersed precious metal Pd was further prepared by the impregnation method，which clearly performed excellent catalytic performances in both hydrogenation of nitrobenzene and oxidation of benzyl alcohol. Due to the abundant mesoporous pore structure and highly dispersed loaded precious metal Pd，the mesopo⁃ rous Pd/γ-Al₂O₃ microspheres achieved 93.78% nitrobenzene conversion and 98.58% aniline selectivity after 30 min，which are respectively 15.55% and 17.58% higher than that of the commercial nanoparticle Pd/γ-Al₂O₃，the catalytic performance remained essentially unchanged after recycling. The benzyl alcohol conversion realized a remarkable increase of 26.39% compared to the comparison sample and remained unchanged in a long time oxidation reaction of benzyl alcohol. This work will provide a new strategy for developing high-performance porous γ-Al₂O₃ loaded catalysts.