Effects of La2O3, CeO2 and LaPO4 introduction on vanadium tolerance of USY zeolites.

Rare earth compounds were employed as vanadium traps in USY zeolite. USY zeolites containing La 2 O 3 , CeO 2 and LaPO 4 were prepared by precipitation method and characterized by means of BET, TEM, XPS, XRD and Rietveld refinement. The results indicated that the rare earth oxides were highly dispersed in zeolites and some of rare earth cations moved to zeolite cages, which improved the hydrothermal stability and catalytic activity of zeolites. In LaPO-USY zeolite, rare earth specie, as LaPO 4 , was distributed on the zeolite surface and did not affect the properties of catalyst. With rare earth elements at the same contents, the vanadium resistances of zeolites followed a descending order of LaPO-USY > Ce-USY > La-USY > USY. The significant differences between activation energies of zeolite destruction can be attributed to various vanadium tolerances. [ABSTRACT FROM AUTHOR]