Enhanced stability of Pd/Al2O3 during aqueous oxidation reaction via SiH4 treatment

γ-Al₂O₃ is widely present as a support in catalytic application. However, the transformation of γ-Al₂O₃ into the undesired hydrated boehmite (γ-AlOOH) under the aqueous reaction conditions usually results in an irreversible inactivation of supported Al₂O₃ catalysts. Toward suppressing the hydration of γ-Al₂O₃ in the process of catalytic reactions, herein we have devised a new strategy by exploring the SiH₄ treatment for successful preparation of Si–Pd/Al₂O₃ catalysts. SiH₄ treatment enables a significant improvement in the poor stability of Pd/Al₂O₃ for selective oxidation of toluene because SiH₄ could effectively anchor palladium nanoparticles and inhibit the formation of boehmite by reacting with unsaturated aluminum sites to reduce the intensity of Lewis acid sites on the surface of γ-Al₂O₃. Pd/Al₂O₃ pretreated with SiH₄, that is Si–Pd/Al₂O₃, provides high catalytic activity and stability in the aqueous oxidation of toluene even at high temperature. Moreover, Si–Pd/Al₂O₃ is reusable without obvious loss of the catalytic activity and selectivity, compared to Pd/Al₂O₃.