Effect of vanadium contamination on H-ZSM-5 zeolite deactivation

A series of H-ZSM-5 zeolite was deactivated by vanadium impregnation followed by a steaming treatment. Textural properties and total acidity measured by n-hexane cracking were determined before and after hydrothermal treatment (steaming). After vanadium impregnation, a decrease in n-hexane conversion was observed suggesting acid sites poisoning by vanadium species. Steaming treatment resulted in an additional decrease in n-hexane activity which can be probably assigned to the dealumination process that takes place during steaming. Dealumination process presented evidences of being vanadium-assisted, although the products selectivities of n-hexane cracking were not significantly affected.