Deactivation of HY-type zeolite catalyst due to coke deposition during gas-oil cracking

Abstract

Abstract Deactivation mechanism of high siliceous Y-type zeolite catalyst was analyzed for catalytic cracking of gas-oil. First, catalytic properties, such as the amount of strong acid sites, the intracrystalline diffusivity and the accessible pore space for reactant molecules, were measured for a series of coked Y-type zeolite catalysts with different coke loadings. The relations of the coke loading to the changes in the catalytic properties were obtained. Using these relations, model equations were proposed for representing the deactivation of Y-type zeolite catalyst under the reaction control condition and the diffusion control condition. The comparison of the calculated by the model equations with the experimental data clarified that the catalytic cracking of gas-oil proceeded under the diffusion control condition, and the reduction of accessible pore space for reactant molecules was dominant factor of the deactivation.