Regeneration of used RFCC catalyst and catalytic properties of novel RFCC catalyst

Abstract

Three different regeneration methods to recover the catalytic activity of spent RFCC (resid fluid catalytic cracking) catalyst were investigated. Carbochlorination method was the most effective to remove contaminant metals from spent E-cat (equilibrium catalyst). However, catalytic activity was not restored due to severe chlorination condition. The attempt to remove Fe, Ni, and V as a volatile corresponding metal carbonyl compound from E-cat was not effective due to low reactivity between contaminant metals and CO. The most effective method to rejuvenate spent E-cat was washing with weak acid after converting metals to a water-soluble form by calcination. EPMA (electron probe micro analysis) for the cross-sectional profile of Ni, Fe, and V of the regenerated catalyst particle showed that three regeneration methods removed Ni, Fe, and V uniformly throughout the catalyst particle. The preparation of the fresh RFCC catalyst was studied to enhance catalytic properties and the metal resistant ability. The distribution of acid sites and the activity in various RFCC catalysts was compared. The weak acid site in zeolite Y diminished and converted to strong acid site by the dealumination. The function of the weak acid site was to raise gasoline and paraffin yield. The strong acid site generated by the dealumination raised the yield of C3 and C4 olefin and enhanced the cracking of hydrocarbons having high molecular weight. The fresh RFCC catalysts were prepared with metal traps that could reduce the effect of the deactivation by nickel, vanadium and iron. The activity of the catalyst was measured with MAT and a cracking reaction which used n-hexadecane as a model feed. When 2.6 wt% of MgO was added to the catalyst, the catalytic activity of the catalyst produced was highest after the metal impregnation and the steam deactivation. The addition of 1.3 wt% of CaTiO3 and MgTiO3, respectively, could also reduce the effect of deactivation by metal. 4 kg of fresh RFCC cat...