Modeling of Hydrodesulfurization Catalysts. I. Influence of Catalyst Pore Structures on the Rate of Demetallization

Abstract

A mathematical model to describe catalyst deactivation during residuum hydrodesulfurization (HDS) has been applied to catalyst systems of different pore structures. Simulations were carried out on the hydrodemetallization (HDM) reaction, which usually leads to the steady accumulation of metals during HDS. Catalyst activity decays with time both linearly and nonlinearly depending on the pore structure. Predicted lifetimes for three different pore structures show that the catalyst can deactivate within 5−15 months. The results of the simulations indicate that better service life could be achieved with improved catalyst design involving pore structure modifications.

Modelling of hydrodesulfurization catalysts

“…All the major assumptions made have been presented elsewhere [11,12]. The heterogeneous catalyst system was Nomenclature C instantaneous concentration of reactant C M instantaneous concentration of reactant for the macropore system C 0 initial concentration of reactant for the random pore system (kmol/m 3 ) C 0 M initial concentration of reactant for the macropore pore system (kmol/m 3 ) D bulk diffusivity D e effective diffusivity D em effective diffusivity for the micropore system D eM effective diffusivity for the macropore system D m bulk diffusivity for the micropore system D M bulk diffusivity for the macropore system D rM restricted diffusivity for the macropore system E m microregion void fraction E M macroregion void fraction K reaction rate constant per unit surface area K M deposition velocity defined by Eq.…”

“…A procedure for incorporating pore size distribution in the macro and micropores for calculating effectiveness factor (h) and the reaction rate per unit volume of catalyst (R v ) for a second order reaction is available [9][10][11][12]:…”

“…The models developed for the macro-, micro-and the random pore systems were simulated by the use of computer. The program for the three models was written in BASIC computer language [12].…”

“…Increased attention is directed at finding an optimum pore size for HDM catalysts and this depends on the quality of the feedstocks. The present investigation is aimed at applying a previously developed model to determine the effect of macro-, micro-and random pore structures on HDM catalysts [9][10][11][12][13].…”

Preparation of a mesoporous sorption complex catalyst and its evaluation in reactive sorption enhanced reforming

“…Previous studies (Inoue et al, 1988;1991;Oyekunle and Ikpekri, 2004;Gong et al, 2005) have shown that a larger pore size and a greater number of pores promote the reactions by facilitating the transmission of heat and mass into and out of the catalyst. Moreover, it is well known that high porosity implies high surface area, which provides a large number of reactive sites.…”