物理化学学报 >> 2002, Vol. 18 >> Issue (08): 680-685.doi: 10.3866/PKU.WHXB20020803

研究论文 上一篇    下一篇

甲烷在中孔分子筛MCM-41中吸附的计算机模拟

张现仁;汪文川   

  1. 北京化工大学化学工程学院,北京　100029
  • 收稿日期:2001-12-12 修回日期:2002-01-16 发布日期:2002-08-15
  • 通讯作者: 汪文川 E-mail:wangwc@buct.edu.cn

Molecular Simulation on Adsorption of Methane in Mesopore MCM-41

Zhang Xian-Ren;Wang Wen-Chuan   

  1. College of Chemical Engineering, Beijing University of Chemical Technology, Beijing　100029
  • Received:2001-12-12 Revised:2002-01-16 Published:2002-08-15
  • Contact: Wang Wen-Chuan E-mail:wangwc@buct.edu.cn

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摘要： 采用巨正则系综Monte Carlo方法研究了甲烷在两个不同孔径的MCM-41中不同温度下的吸附等温线和其在孔中的相行为和排列方式.模拟结果显示,在较小孔径的MCM-41中,流体分子达到毛细凝聚所需的化学位较小,并且观察到两个孔径下计算机模拟得到的亚稳态区域都非常宽,使得层状转变（如果有的话）被包含在这个区域.通过比较两种孔径下达到毛细凝聚后的构型,可以看出,在3.5 nm的孔中流体的分子结构出现非常有序的排列,而在5.0 nm的孔中则没有.在常温300 K时甲烷的吸附的计算机模拟表明,孔壁对流体分子的作用仅仅影响较靠近壁面附近的流体分子的排列,而对孔中间的分子几乎没有影响.

关键词: 甲烷, 吸附, MCM-41, 计算机模拟

Abstract: Using grand canonical ensemble Monte Carlo method, adsorption isotherms, phase transition behaviors and structures of methane adsorbed in two pores of MCM-41, with 3.5 and 5.0 nm diameters, at 74.05 K and 300 K have been simulated. It is found that capillary condensation occurs at a lower chemical potential for the smaller MCM-41 at 74.05 K, compared that with the pore of 5.0 nm. For the two pore sizes in this study, hysteresis loops of capillary condensations are so wide that layering transitions are found within them. In the two MCM-41 pores at 74.05 K, a highly ordered structure for methane molecules in 3.5 nm pores is observed, in contrast to less ordered arrangement of the molecules for the 5.0 nm pore. When the temperature is increased to 300 K, only methane molecules near the walls of MCM-41 are arranged in order, while the molecules near the centers of pores are arranged almost randomly.

Key words: Methane, Adsorption, MCM-41, Computer simulation