Highly-efficient Ru/Al–SBA-15 catalysts with strong Lewis acid sites for the water-assisted hydrogenation of p-phthalic acid

Abstract

Ruthenium nanoparticles supported onto aluminum-doped mesoporous silica catalysts (Ru/Al–SBA-15) are fabricated using hydrothermal and impregnation methods for catalysis application. The Ru/Al–SBA-15-3 catalyst at a Si/Al molar ratio of 3 exhibited excellent catalytic performance for the hydrogenation of p-phthalic acid with high conversion efficiency (100.0%) and cis-isomer selectivity (84.0%) in water. Moreover, this system displays exceptional stability and recyclability through preserving the conversion efficiency, as well as a cis-isomer selectivity of 90.2 and 83.3%, respectively, after reusing it fourteen times. Such an exceptional system can also be ideal for the hydrogenation of aromatic dicarboxylic acids and their ester derivatives in water. Strong Lewis acid sites due to doped Al species play significant roles in the hydrogenation reaction. Moreover, isotope labeling studies indicated that water molecules effectively participated in the hydrogenation reaction. Hydrogen and water contributed half of the hydrogen atoms for this hydrogenation reaction. In the end, a plausible mechanistic pathway for the hydrogenation of p-phthalic acid using the Ru/Al–SBA-15-3 catalyst in water is proposed.