Abstract:

The cracking performance of ethylcyclohexane on a mesoporous catalyst based on ZSM-5 molecular sieve was investigated in an apparatus with a fixed-bed reactor. The results showed that ethylcyclohexane had good cracking performance, the conversion was above 80%, the yield of ethylene and propylene reached 41% (mass), the yield of total light olefins was near 50% (mass), and the main components of liquid products were benzene, toluene and xylene. As reaction temperature increased, the yield of ethylene increased monotonously, and those of propylene and butene showed maxima. With the consideration of both thermal and catalytic reactions, a kinetic model involving 14 reactions was established for the catalytic pyrolysis of ethylcyclohexane. The experimental data were obtained at reaction temperatures of 600, 620, 640 and 660℃, and the reaction rate constants were estimated by genetic algorithm regression analysis. Apparent activation energies and pre-exponential factors were subsequently calculated according to the Arrhenius equation. All of the apparent activation energies obtained were below 90 kJ·mol^-1, indicating that the mesoporous ZSM-5 catalyst provides high catalytic activity for ethylcyclohexane catalytic pyrolysis. The model predicted values were in good agreement with the experimental data, and the average relative errors of the main products were below 10%.

Key words: reaction kinetics, catalysis, fixed-bed, ethylcyclohexane, ethylene, propylene

摘要：

利用小型固定床实验装置研究了乙基环己烷在基于ZSM-5分子筛介孔催化剂上的裂解性能，发现乙基环己烷具有较好的裂解性能，原料转化率在80%以上，乙丙烯收率（质量分数）可达41%，低碳烯烃收率（质量分数）接近50%，液体产物主要是苯、甲苯、二甲苯等芳香烃。同时考虑乙基环己烷催化裂解过程中的热反应与催化反应，建立了包含14个反应的动力学模型。基于4个反应温度下的裂解实验数据，求取了反应动力学模型的参数。求得的表观活化能均在90 kJ·mol^-1以下，主要组分收率的模型预测值与实验值的平均相对误差不高于10%。

关键词: 反应动力学, 催化, 固定床, 乙基环己烷, 乙烯, 丙烯