Vanadium contamination on the stability of zeolite USY and efficient passivation by La₂O₃ for cracking of residue oil

It is of great significance to identify the destructive role of high deposited vanadium on the USY-based cracking catalysts and find a facile approach to vanadium passivation for processing residue oil. Herein, the destruction degree of the steam-treated vanadium-contaminated USY zeolites, which also contained a certain amount of Na ions, was investigated by N₂ physical adsorption, NH₃-TPD, HRTEM, ²⁷Al MAS NMR and catalytic cracking evaluation. The results reveal that high deposited vanadium causes severe damage to the structure of USY, resulting in a sharp deterioration in cracking performance. Furthermore, CeO₂ and La₂O₃ were studied as vanadium passivating agents. The introduction of La₂O₃ using physical mixing could preserve the zeolite structure to a large extent without altering the properties of USY. The superior passivation performance might be mainly attributed to the fact that La₂O₃ introduced by simple physical mixing prefers to interact with vanadium species, rather than migrate into the channels and cavities of zeolites USY.