Adsorption of thiophene compounds on MoO3/γ-Al2O3 catalysts with different mesopore sizes

Abstract

γ-Al2O3 without amorphous domains was synthesized by cation-anion double hydrolysis method. The mesopore size in the range of 3.9–8.5 nm was easily controlled by regulating crystallization temperature, solution pH value and the concentration of NaAlO2. The introduction of MoO3 to the γ-Al2O3 via impregnation method can lead to a decrease of specific surface areas, pore sizes and pore volumes of the supports. The less steric hindrance of the larger mesopores (particularly 8.5 nm) exhibits the more Lewis acid sites over the γ-Al2O3. The MoO3/γ-Al2O3 possesses more Bronsted acid sites compared to Lewis. The thiophene compounds can be adsorbed both on the supports and catalysts. The acid sites can facilitate the interaction between the thiophene compounds and catalysts (or supports). The more adsorbed thiophene and dibenzothiophene on the catalysts is attributed to the coordinately unsaturated metal sites and Bronsted acid sites on the surface of the catalysts. Of note is the supports and catalysts with larger pore size (especially 8.5 nm) could promote the adsorption of thiophene compounds. It demonstrates that there is pore confinement effect in the hydrodesulfurization catalysts.