二甲苯在AlPO4-5分子筛中吸附的分子模拟研究

采用巨正则蒙特卡罗法(GCMC)研究了二甲苯异构体在AlPO4-5中的吸附，得到了有关吸附平衡常数、吸附热、吸附等温线及吸附位等信息．结果表明，在303K时，邻二甲苯的吸附量高于其它异构体；而在523和573K时，对二甲苯的吸附量最高．低吸附量时二甲苯的平均势能基本不发生变化，而高吸附量时二甲苯的平均势能随着吸附量增加而降低，尤其邻二甲苯的平均势能变化更加明显．由此对二甲苯各异构体在AlPO4-5中的吸附量差别以及它们在分子筛中的排列方式进行了讨论．

Molecular Simulation of Xylene Adsorption in AlPO4-5 Molecular Sieves

The adsorption of xylene isomers in AlPO_4-5 at 303~675 K was simulated by Monte Carlo method with the software Cerius~2 of MSI. The isotherms and the average potential energy of xylene isomers in the framework were obtained. It was observed that the adsorption capacity for o-xylene was the highest among the isomers at low temperature, which could be well interpreted based on the packing of adsorbates in the channel of molecular sieves; by contrast, the adsorption capacity for p-xylene was the highest at high temperature. Moreover, the average potential energy kept constant at low loading, but decreased with the loading at higher loadings; especially, the average potential energy of o-xylene showed a sharp decrease at high loadings. Such results were explained with the structure of AlPO_4-5 and the interaction between the adsorbates and the sorbent's framework.