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采用量子化学法研究了模型化合物正己烷裂解过程,并计算其动力学参数。依据自由基理论,建立由216个基元反应组成的正己烷裂解反应自由基模型,用CBS-QB3法计算链引发和终止反应动力学参数,用MPW1B95/6-311+G(2d,2p)法计算链增长反应动力学参数。根据动力学参数计算结果,忽略相对不重要的反应,将模型简化为160个基元反应。模拟计算表明,在相同的裂解条件下,简化模型模拟结果与完整模型模拟结果一致,各组分相差不大于0.1%wt;建立的动力学模型对主要产物收率预测较好,与实验值相差小于0.7%wt,可正确地预测正己烷裂解产物的组成和各组分含量沿反应管长度的分布,为进一步研究复杂的烃裂解过程提供了基础。
The model compound n-hexane cracking process was studied by quantum chemistry method and its kinetic parameters were calculated. Based on the free radical theory, a radical model of n-hexane cracking consisting of 216 motifs was established. The kinetic parameters of chain initiation and termination were calculated by CBS-QB3 method. The kinetic parameters of MPW1B95 / 6-311 + G (2d, 2p) Method for Calculating Chain Growth Reaction Kinetic Parameters. Based on the kinetic parameters, ignoring the relatively unimportant reactions, the model is reduced to 160 elementary reactions. The simulation results show that under the same cracking conditions, the simulation results of the simplified model are consistent with the simulation results of the complete model, and the differences between the components are not greater than 0.1% wt. The established kinetic model predicts the yield of the major products better than the experimental values Less than 0.7% wt can correctly predict the composition of n-hexane cracking products and the distribution of each component along the length of the reaction tube, which provides a basis for further study on complex hydrocarbon cracking process.