Vanadium-nickel interaction in REY zeolite

Abstract

The interaction of vanadium and nickel in REY zeolite has been determined by X-ray diffraction, Fourier-transform infrared spectroscopy, surface area measurement, temperature-programmed desorption of ammonia and the n-hexane cracking reaction. During steam treatment, the presence of vanadium in REY causes dealumination of the REY framework and partial collapse of the REY structure. Under the n-hexane cracking reaction, vanadium can also promote the coke formation rate of REY zeolite. The crystallinity of REY is not affected by the presence of nickel during the steam treatment. However, the addition of nickel greatly increases coke formation rate of REY zeolite during n-hexane cracking reaction. Most importantly, nickel can inhibit the destruction of the REY structure caused by vanadium. In addition, vanadium can inhibit the coke formation caused by nickel. It is suggested that vanadium may interact with nickel in some way leading to a decrease in the mobility and acidity of vanadium. This decreases the vanadium's ability to damage REY zeolite. On the other hand, the interaction makes nickel more difficult to be reduced and, therefore, less coke is produced in REY zeolite during the n-hexane cracking reaction.