Enhanced Catalytic Performance of the FCC Catalyst with an Alumina Matrix Modified by the Zeolite Y Structure-Directing Agent

The surface acid property of γ-Al<sub>2</sub>O<sub>3</sub> has been modified by a zeolite Y structure-directing agent (SDA). Thus, modified γ-Al<sub>2</sub>O<sub>3</sub> as a matrix material was used in fluid catalytic cracking (FCC) catalysts, and its performance of cracking vacuum gas oil (VGO) was evaluated. In comparsion with unmodified γ-Al<sub>2</sub>O<sub>3</sub>, the modified matrix material exhibited superior catalytic performance with heavy oil conversion increased by 5.64%, enhancing the gasoline yield by 2.19% and the LPG yield by 3.00%. Characterization results indicated that the zeolite Y SDA modification effectively introduced Si species into the framework of γ-Al<sub>2</sub>O<sub>3</sub>. The interaction between hydroxyl groups on silanol and Al–OH led to the formation of bridged hydroxyl groups (Si–OH–Al), which are the origin of medium-strength Brönsted acid sites on the modified alumina matrix accounting for the enhanced catalytic performance of FCC catalysts.