基于两步机理的高温费托合成总包动力学研究

摘要

The Fischer-Tropsch synthesis (FTS) including water gas shift reaction on a precipitated iron catalyst could be approximated as a single reaction that forms an average hydrocarbon with water and carbon dioxide as its by-products, and the overall reaction was derived on the basis of carbon number distribution of high temperature Fischer-Tropsch synthesis products. A set of overall reaction kinetics models were developed from two-step mechanism in which the surface inhomogeneity of the catalyst and the compensation effect of catalyzed reaction were taken into account. The high temperature Fischer-Tropsch synthesis were examined in a continuous stirred tank reactor with an industrial precipitated iron catalyst. Model discrimination and parameter estimation were performed based on the kinetic data. It was concluded that the values of kinetic parameters for the models agree well with the data reported in literatures and the optimized model was derived from two-step mechanism based on taking carbon monoxide chemisorption as rate determining step and butane as average hydrocarbon product of the overall reaction.%　　为进行非均匀表面费托合成反应动力学的研究，将费托合成作为单个反应处理，以高温费托合成产物碳数分布为依据，得到高温费托合成总包反应方程。由两步机理出发，考虑催化剂表面的非均匀性和催化反应的补偿效应，按照吸附控制和反应脱附控制两种情况构建了四类费托合成总包动力学模型。使用工业高温沉淀铁催化剂，依据从无梯度反应器获取的高温费托合成动力学实验数据，对建立的动力学模型进行参数回归和检验，结果表明各模型的表观活化能计算结果与文献相符，其中以一氧化碳吸附作为速率控制步骤和以丁烷作为总包反应平均产物得到的总包动力学模型最优。