Amorphous silica-alumina – perspective supports for selective hydrotreating of FCC gasoline: Influence of Mg

Abstract

CoMo/Al2O3-ASA catalysts with Mg were synthesized. Catalysts differed in the way of Mg addition: 1. Mg was added to ASA, 2. Mg was added to the kneading paste during the support preparation, 3. Mg was added before or after Co and Mo by the impregnation. Catalysts were characterized by the following techniques: low-temperature N2 adsorption, IR of CO and CO2 adsorption, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy. Synthesized catalysts were tested in hydrotreating of the model fluid catalytic cracking gasoline containing 250 ppm of sulfur from thiophene, 40 wt.% of toluene, 40 wt.% of heptane and 20 wt.% of n-hexene-1. It was found that the addition of Mg resulted in changes of physico-chemical properties of catalysts and their HDS and HYD activities. The way of Mg addition influenced the content of Lewis and Brønsted acid sites and morphology of sulfide active component. Mg increased HDS activity and decreased octane number loss. The catalysts with Mg in the kneading paste of the support and with Mg added after active metals showed the best combination of HDS activity and selectivity.