Intraparticle diffusional effects and kinetics of desulfurization reactions and asphaltenes cracking during catalytic hydrotreatment of a residue

Abstract

The cracking of asphaltenes and the desulfurization of asphaltenic and non-asphaltenic fractions of a residue were studied in a bench-scale, tubular, trickle bed reactor. Reaction conditions were 50 bar and 350-430°C. Two types of commercial Co-Mo/Al2O3 catalysts were used. The experimental intrinsic rate data were described by the power-law rate equation for both cracking of asphaltenes and desulfurization reactions of the asphaltenic and non-asphaltenic fractions. The values of the effective diffusivity for each type of reaction have been determined from data derived from experiments carried out by using catalyst extrudates. The ratios of the effective diffusivities for the bimodal catalyst to those for the unimodal catalyst were equal to 2.9 ± 0.1 for both cracking and desulfurization reactions. The effective diffusivities for cracking and desulfurization reactions of asphaltenes were identical for both catalysts used. © 1988 American Chemical Society.