苯与丙烯在β分子筛上吸附行为的蒙特卡罗研究

Adsorption of Benzene and Propene in β Zeolite by Grand Canonical Monte Carlo Simulation

采用巨正则统计系综蒙特卡罗模拟方法研究了β分子筛上苯与丙烯分子的吸附行为.由分子筛内吸附质粒子云分布可知,在100kPa时,丙烯在分子筛上的吸附量要远远大于苯的吸附量.由吸附相互作用能分布来看,苯与分子筛之间相互作用能比丙烯与分子筛之间的相互作用能更负,这就使苯分子的吸附相对于丙烯分子稳定.相对而言,温度变化对丙烯吸附影响远大于对苯吸附的影响,如100kPa时,温度由298K升高至443K导致丙烯分子吸附量明显减少,由每8个晶胞吸附98个丙烯分子减少到80个;而对苯分子吸附却没有显著的影响.β分子筛上存在着苯和丙烯的竞争吸附,并且吸附分子之间存在相互作用使两者与分子筛之间的相互作用能分布改变.在压力范围1×10-3～5.0kPa,不同温度下苯与丙烯在分子筛内吸附等温线的模拟结果表明,在较高温度、较低压力下丙烯的吸附量要小于苯的吸附量.

The adsorption behavior of benzene and propene in β zeolite has been studied by grand canonical Monte Carlo （GCMC） simulations. From the mass clouds of GCMC simulations, it can be found that the benzene and propene molecules show different adsorption behavior in the zeolite cavities. The loadings of propene are significantly larger than those of benzene at 100 kPa. From the figures of potential energy distribution, the potential energy of propene and zeolite is higher than that of benzene and zeolite, so benzene can adsorb more stably than propene. When the temperature rose from 298 to 443 K at 100 kPa, the number of propene was reduced from 98 to 80, while benzene changed little. When benzene and propene adsorbed in zeolite at the same time, there are competitive adsorption, therefore the potential energy distribution could be changed significantly. The adsorption isotherms of benzene and propene at different temperatures and 1 × 10^-3-5.0 kPa show that at low pressure and high temperature, the loadings of propene are significantly lower than those of benzene.