Elucidating the interaction of FCC catalyst components: the discrete roles of matrix and binder on zeolite structure

Zeolite Y is the active phase of the modern fluid catalytic cracking (FCC) catalyst. However, a functional and active FCC catalyst comprises, in addition to zeolite Y, matrices and a binder that introduce some levels of synergistic interaction between the catalyst components, impacting its activity. This study investigates the interactive properties of a zeolite-matrix-binder composite on a typical FCC catalyst using various characterization techniques. Characterization of synthesized FCC catalyst samples reveals changes in the structural composition of zeolite Y dependent upon the type and ratio of binder materials. The binder is important in the crystallization of the final composite. Acidic binder induces dealumination of zeolite, leading to amorphization, loss of Brønsted acid sites, framework structure impairment, and the formation of defective sites. TEM indicates the formation of zeolite-matrix interfaces upon binding of zeolite by the matrix. Depending on the extent and severity of thermal processing, the clay–alumina–silica binder undergoes dehydroxylation to varying degrees by cross-linking of terminal hydroxyl groups between neighboring binder particles, which contributes to the increased thermal and mechanical stability of the bound catalysts.