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

Authors

  • Zhigang Wang,

    1. State Key Laboratory of Heavy Oil Processing, Chemical Engineering Dept., College of Chemical Engineering, China University of Petroleum, Beijing, P.R. China
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  • Sheng-Li Chen,

    Corresponding author
    1. State Key Laboratory of Heavy Oil Processing, Chemical Engineering Dept., College of Chemical Engineering, China University of Petroleum, Beijing, P.R. China
    • Correspondence concerning this article should be addressed to S.-L. Chen at slchen@cup.edu.cn.

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  • Jianing Pei,

    1. State Key Laboratory of Heavy Oil Processing, Chemical Engineering Dept., College of Chemical Engineering, China University of Petroleum, Beijing, P.R. China
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  • Aicheng Chen,

    1. State Key Laboratory of Heavy Oil Processing, Chemical Engineering Dept., College of Chemical Engineering, China University of Petroleum, Beijing, P.R. China
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  • Junhui Zhang,

    1. State Key Laboratory of Heavy Oil Processing, Chemical Engineering Dept., College of Chemical Engineering, China University of Petroleum, Beijing, P.R. China
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  • Zhiming Xu,

    1. State Key Laboratory of Heavy Oil Processing, Chemical Engineering Dept., College of Chemical Engineering, China University of Petroleum, Beijing, P.R. China
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  • Jay B. Benziger

    1. Dept. Chemical and Biological Engineering, Princeton University, Princeton
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Abstract

Well-defined and uniform pore structure catalysts were used to study the intraparticle diffusion of fractionated Saudi vacuum residue under hydrodesulfurization (HDS) reaction conditions. HDS rates of residue oil cuts with different molecular weights are determined as functions of pore size, temperature, and pressure in a trickle-bed reactor. Credible intrinsic and bulk diffusivities of organosulfur compounds in residue oil were obtained for the first time, from the apparent and intrinsic reaction kinetic constants. Intrinsic diffusivities ranged from 2 × 10−7 to 8 × 10−7 cm2/s for the residual oil molecules; diffusivity decreases with increasing molecular weight of the residual oil. The intrinsic diffusivity for molecular weights ∼1000 Daltons increases with pore size for pores <70 nm, but is nearly independent of pore size for pores >70 nm. The diffusivity dependences on pore size and molecular weight suggest that the onset of restricted diffusion occurs for ratios of molecular diameter to pore diameter of ∼0.04. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3267–3275, 2014

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