C4烯烃组成变化对烷基化反应热力学行为的影响

Impact of C olefins composition changes on thermodynamic behavior of alkylation

针对丁烯资源中异丁烯体积分数增加、烷基化C4原料组成变化引起生产波动的现状,借助热力学方法对1-丁烯、2-丁烯、异丁烯与异丁烷在-10~50℃内液相烷基化反应特征进行分析。结果表明,烷基化反应为不可逆放热反应,放热量随温度升高略增大,生成目的产物放热量略大于生成副产物放热量,异丁烯烷基化反应放热量最小;不同丁烯烷基化反应平衡转化率均在99.9%以上,异丁烯烷基化平衡转化率略低于其他2种烯烃,主、副反应平衡转化率均随温度升高略降低;辛烷值较高的TMP的选择性随温度升高而降低,而副产物DMH、MH选择性增加。随着C4原料中异丁烯体积分数的增加,烷基化目的产物的选择性略降,且随着温度的升高降低趋势增强,温度对烷基化产物辛烷值影响敏感,有效控制并稳定反应温度可弥补烷基化产品质量的损失。

In the light of the production fluctuation caused by the increasing isobutylene content in butene resources and the change of C4 raw material compositions for alkylation,the liquid phase alkylation characteristics of 1-butylene,2-butylene,isobutylene and isobutane in the range of-10℃-50℃are analyzed by means of thermodynamic method.Results show that alkylation reactions are all irreversible exothermic reactions,the heat release increases slightly with the higher temperature,heat release for target product is slightly greater than that for by-product,and the alkylation reaction of isobutylene release the least heat.The equilibrium conversion rates of different butylenes are all above 99.9%,and that of isobutylene are slightly lower than other two butylenes.The equilibrium conversion rates of main and side alkylation reactions all drop slightly when the temperature goes up.The selectivity of TMP with higher octane number decreases with the increasing temperature,while that of DMH and MH increases with higher temperature.With the increase of isobutylene content in C4 raw materials,the selectivity of alkylation target products decreases slightly,and the decreasing trend enhances with the increasing temperature.Temperature can generate sensitive influence on octane number of alkylation products,and the effective control and stability of reaction temperature can make up for the loss in quality of alkylation products.