Preparation and properties of filled monolayer of MoO3 deposited on Al2O3 supports by solvent-assisted spreading

Catalysts MoO3/Al2O3 were prepared by solvent-assisted spreading method, which is the reaction of Al2O3 support with the slurry of MoO3 in water. Fifteen Al2O3 supports with surface area SBET in the range of 11-279 m2 g−1 were used. The method belongs to equilibrium adsorption impregnation methods and provides the catalysts with filled monolayer of molybdena species; the formation of bulk MoO3 and Al2(MoO4)3 is avoided. The saturated adsorption loading, corresponding to filled monolayer loading, linearly increased with SBET and the mean density of filled monolayer calculated from the slope was 3.4Mo nm−2. The deposited-filled monolayer was X-ray amorphous. Two reduction peaks were observed by temperature-programmed reduction. Their position was independent of Al2O3 surface area indicating the same quality of filled monolayer in all catalysts. The samples were sulfided and their activity in hydrodesulfurization (HDS) of thiophene (TH) at the pressure of 1 MPa and temperature 280-400 °C was tested. Activation energy of all samples was similar and their activity increased linearly with saturated adsorption loading; that again proves the same quality of filled monolayer independently of SBET of Al2O3. It was found with four Al2O3 that the catalysts prepared by solvent-assisted spreading were equally or more active (by up to 37%, depending on Al2O3) as compared with the corresponding catalysts prepared by conventional impregnation using (NH4)6Mo7O24 solution.