丙烯在X型分子筛上吸附热力学的Monte Carlo模拟

Monte Carlo simulation for thermodynamics of propylene adsorption on X-type molecular sieves

基于Materials Studio软件的Metropolis Monte Carlo方法,运用COMPASSⅡ力场模拟了丙烯在Na X及其金属离子改性分子筛上的吸附,探究了丙烯在X型分子筛上的吸附等温线和吸附热的变化规律。研究结果表明,采用Materials Studio搭建的Na X分子筛构建合理,可用于模拟吸附丙烯分子;丙烯在X型分子筛上的吸附等温线属于Ⅰ类Langmuir型吸附等温线,同一温度下,随压力的增加达到吸附平衡时,丙烯在X型分子筛上的吸附热与吸附量之间呈现良好的正相关性;KX分子筛的平衡吸附量为1.63 mmol/g,吸附热为32.05 k J/mol,为物理吸附,相比Na X分子筛,平衡吸附量降低了56.18%,吸附热降低了27.86%,更适用于丙烯的净化。

The adsorption of propylene on Na X molecular sieves and its metal ion modified ones is simulated using COMPASS Ⅱ force field,based on the Metropolis Monte Carlo method in Materials Studio,and the change law for the adsorption isotherm and adsorption heat of propylene on X-type molecular sieves is investigated.The results show that the Na X molecular sieves constructed by Materials Studio are reasonable and can be used to simulate the adsorption of propylene molecules.Ⅰtype Langmuir adsorption isotherm is observed for the adsorption of propylene on X-type molecular sieves,and at the same temperature,when the adsorption equilibrium is achieved with the increase of pressure,there is a good positive correlation between the adsorption heat and the adsorption capacity of propylene on X-type molecular sieves.For KX molecular sieves,the physical absorption is observed with the equilibrium adsorption capacity of 1.63 mmol/g and the adsorption heat of 32.05 k J/mol.Compared with Na X molecular sieves,KX molecular sieves are more suitable for the purification of propylene due to a reduction of 56.18% in equilibrium adsorption capacity and a reduction of 27.86% in adsorption heat.