Hydrogenation and hydrodesulfurization in gas phase of light hydrocarbons from hydrocracking, desulfurization and delayed coking. I catalyst deactivation

Abstract

Hydrogenation and hydrodesulfurization reactions of hydrocarbons in gas phase was studied in a fluidized-bed reactor using PdNiW/TiO2-Al2O3 and NiMo/TiO2Al2O3 catalysts. Catalyst deactivation was performed at different temperatures and using hydrocracking product with and without delayed coking naphtha feeds. Delta of species and catalysts activities were measured, and catalyst characterized by physical and chemical properties, metals and carbon dispersion, acid sites content and benzene diffusivity in hydrogen. Coke was extracted by CS2 and analyzed by MAS 13C NMR. There are different rates of sites deactivation when processing gas feed with or without olefinic hydrocarbons on these catalysts. Olefins and diolefins produce carbon deposits fast; carbon distribution across the radius of particle depend on temperature and amounts of aromatics in the feed. Reaction and deactivation rates constants were obtained for each of catalysts. The simulation model used only predicted well products properties without olefins and diolefins. The mechanism of reaction are discusses based on solid characterizations.