Effect of restrictive diffusion on hydrodesulfurization of heavy residue oils over CoMo/Al₂O₃

Abstract

The effect of the ratio of reactant molecular diameter to catalyst pore diameter (A) on the restrictive diffusion under hydrodesulfurization (HDS) reactions of heavy residue oils over CoMo/A120, catalysts was investigated. A series of AI20, with various pore structures were used as supports of CoMo sulfide. The HDS reaction was carried out in a semi-batch Carberry type reactor at 648 K and 10.3 MPa. Two empirical correlations for restrictive diffusion under HDS reaction conditions were developed depending on the value of X. The results showed that the restrictive diffusion effect under HDS reaction conditions is severe for the lower values of A. However, this effect seems not prominent for higher values of A. The order of the magnitude of the effective diffusivity was in the range of 10-6-10-7 cm2/s for the sulfur-containing compounds of residue oil in CoMolAl,O, catalysts at 648 K.On a mesure I'effet du rapport entre le diamktre molCculaire du rCactif et le diamkre des pores du catalyseur (A) sur la diffusion restrictive dans les rCactions d'hydrodtsulfuration (HDS) d'huiles residuelles lourdes sur des catalyseurs CoMo/A120,. Plusieurs A120, aux structures de pore varites ont Ct C utilisCs comme supports de sulfure CoMo. La rkaction HDS a Ct C menCe dans un rkacteur semi-continu de type Carberry B 648 K et 10,3 MPa. Deux correlations empiriques de la diffusion restrictive dans des conditions de rCactions HDS ont 6tC Ctablies par rapport a la valeur de X. Les rCsultats montrent que I'effet de la diffusion dans des conditions de rCactions HDS est important pour de faibles valeurs de A. L'ordre de grandeur de la diffusivitb effective se situe a 10-6-10-7 cm2/s pour les composes d'huile rtsiduelle contenant du soufre dans les catalyseurs CoMo/A1203 B 648 K.

Insight into the intraparticle diffusion of residue oil components in catalysts during hydrodesulfurization reaction

“… Comparison of experimental restrictive factor data with literature correlations [a and b: Ref. , c: Ref. , d: Ref.…”

“…In previous studies, the Stokes–Einstein and Wilke–Chang equations were used to estimate the bulk diffusivity. However, these equations are only applicable when solution concentration is low and there are no wall effects.…”

“…Many researchers have investigated diffusion of residue oil in catalyst pores by diaphragm, sorptive, and reaction‐kinetic methods . Our research group has developed a method of preparing catalyst supports with well‐defined pore structures.…”