Enhancement of Efficiency of Pd/Al₂O₃Catalysts in Selective Hydrogenation of Sec-Butylbenzene by Modification with H₂SO₄ or H₂WO₄

Hydrogenation of bulky aromatic hydrocarbons is an important problem to be solved in order to improve the quality of fuels. Pd-containing catalysts modified by strong acids have been prepared and studied by diffuse-reflectance IR spectroscopy, and the catalytic activity of the materials has been determined. In studying the selective liquid-phase hydrogenation of sec-butylbenzene as a model substrate, it was shown that modification of Pd/Al2O3 catalysts with acid additives (H2SO4 or H2WO4) results in a significant increase in the hydrogenation activity and selectivity. IR spectroscopy of adsorbed CO and d3-acetonitrile revealed that larger palladium metal particles are formed on the Pd-H2SO4(H2WO4)/Al2O3 catalysts, with ionic states of palladium being present even in the samples reduced in H2.