Silica Gel─A Perspective Component to Increase Catalyst Activity in FCC Gasoline Hydrotreatment

Abstract

The study focuses on the effect of 1–70 wt % silica gel addition on the properties of CoMo/Al₂O₃ catalyst for fluid catalytic cracking gasoline hydrotreating. An increase in silica gel content results in an increase in the specific surface area and pore volume in the supports and catalysts. According to the IR spectroscopy of adsorbed CO and pyridine, the addition of any amounts of silica gel leads to the decrease in LAS concentration, while 30 wt % of silica gel leads to the formation of BAS typical for amorphous aluminosilicate. According to UV–vis spectroscopy and TPR-H₂, the dispersity of oxygen-containing compounds of active metals decreases when silica gel is added. The addition of 5–70 wt % of silica gel results in an increase in the average particle length of the active component from 2.1 to 2.2–2.7 nm and the stacking number from 1.8 to 1.9–2.2. Moreover, there is a correlation between Mo⁴⁺ content and catalyst’s HDS activity. The catalyst with 30 wt % of silica gel had the highest Mo⁴⁺ content and the highest HDS activity. The formation of BAS in the catalysts with 30–70 wt % of silica gel leads to improved activity in isomerization of alkanes and alkenes, aromatization (or cyclization) of alkanes and alkenes, and alkylation of aromatics, and increased octane number of products from 89 to 92–93 points.