Highly dispersed Pd nanoparticles supported on ?-Al2O3 modified by minimal 3-aminopropyltriethoxysilane as effective catalysts for 2-ethyl-anthraquinone hydrogenation

Faced with the problems of poor activity and inferior selectivity, highly dispersed Pd catalysts pre-modified by minimal 3-aminopropyltriethoxysilane (APTES) were prepared via impregnation reduction method. The amount of APTES was adjusted according to molar ratios of the APTES to Pd (APTES/Pd). The catalytic hydrogenation efficiency exhibited a volcano-shape trend with the amount of APTES. Grafting of suitable amount of APTES improved the dispersion of the Pd, increased the weak acid content of the ?-Al2O3 and regulated the reducibility of the catalysts. The catalyst having APTES/Pd = 2 with 0.192 wt% Pd showed the highest catalytic activity and selectivity, with 100 % in the selectivity and the improvement of 27.3 % in the hydrogenation efficiency and 104.8 % in the H2O2 productivity compared with the commercial catalyst (0.298 wt%). Furthermore, the APTES aggregated with the amount of APTES, which provided intense anchoring sites for the Pd and resulted in the increase in larger palladium nanoparticles.