Reaction engineering calculation for ethylene catalytic oxidation over gear-shaped catalysts

doi:10.11949/j.issn.0438-1157.20160081

Abstract

Abstract:

For the reaction of ethylene catalytic oxidation to ethylene oxide over a gear-shaped catalyst particle, a three-dimensional reaction-mass transfer-heat transfer model is developed to calculate effectiveness factor of the catalyst. Effective diffusivities and effective thermal conductivity are the function of temperature and concentration distribution in catalyst particle. The finite element method is employed to solve the set of highly nonlinear partial differential equations, and the values obtained agree well with those given by literatures. Geometric external surface area is a key parameter for the effectiveness factor. The effectiveness factor is 0.1804 for gear-shaped catalyst with geometric external surface area of 1862 m²·m^-3, and 0.0993 for cylindrical catalyst with geometric external surface area of 924 m²·m^-3. The quantitative calculation for reaction-transport phenomena in a single catalyst particle could be a guide for catalyst design and a basis for multi-scale simulation of coupling hydromechanics and catalytic reaction-transport phenomena.

Key words: ethylene oxidation, irregular shape catalyst, transport processes, numerical simulation, internal effectiveness factor

摘要：

针对乙烯氧化制环氧乙烷反应体系，对外齿轮异形催化剂建立三维反应-传质-传热模型。有效扩散系数和有效热导率均为待求解浓度场和温度场的函数，使得偏微分方程组模型为强非线性。采用有限元算法求解，并对模型有效性进行验证，定量研究了催化剂几何比外表面积和内扩散效率因子的关系。计算结果表明，几何比外表面积为1862 m²·m^-3的外齿轮催化剂内扩散效率因子为0.1804，而几何比外表面积为924 m²·m^-3的圆柱形催化剂内扩散效率因子为0.0993。对单个催化剂颗粒反应-传递现象的研究能定量指导催化剂设计，并为耦合反应器流体力学和催化剂反应传递现象多尺度模拟计算奠定基础。

关键词: 乙烯氧化, 异形催化剂, 传递过程, 数值模拟, 内扩散效率因子

CLC Number:

TQ028.8

ZHOU Jipeng, FANG Dingye, LI Tao. Reaction engineering calculation for ethylene catalytic oxidation over gear-shaped catalysts[J]. CIESC Journal, 2016, 67(7): 2808-2814.

周继鹏, 房鼎业, 李涛. 外齿轮形颗粒催化剂上乙烯催化氧化的反应工程计算[J]. 化工学报, 2016, 67(7): 2808-2814.

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