Solvent-free synthesis of mesoporous platinum-aluminum oxide via mechanochemistry: Toward selective hydrogenation of nitrobenzene to aniline

Abstract

Mesoporous alumina (meso-Al2O3) supported noble metal catalysts have been widely used in heterogeneous catalysis. However, these catalysts are generally prepared via wet chemistry, which suffers from several drawbacks, such as: excessive use of solvents and time-consuming drying process. In this manuscript, a mechanochemical method for solid-state processing between aluminum isopropoxide and block copolymers (P123) were introduced to synthesize meso-Al2O3 supported platinum catalyst (Pt/m-Al2O3). The resulting Pt-meso-Al2O3 catalyst shows high surface area (up to 465 m2/g) and uniform pore size (~3.9 nm). Interestingly, the solvent-free ball milling method enables the processing of bulky micrometer-scale Pt precursors into well dispersed Pt nanoparticles (~4.8 nm). Moreover, Pt/m-Al2O3 catalyst affords good performance in the selective hydrogenation of nitrobenzene to aniline (Conversion: >99%, Aniline Selectivity: >99%). This mechanochemical route provides a solvent-free and one-step method for synthesizing meso-Al2O3 supported noble metal catalysts.