Adsorption separation of carbon dioxide, methane, and nitrogen on H beta and Na-exchanged beta-zeolite

作者：Xu, Xiaoliang; Zhao, Xingxiang; Sun, Linbing; Liu, Xiaoqin^*

来源：Journal of Natural Gas Chemistry, 2008, 17(4): 391-396.

DOI：10.1016/S1003-9953(09)60015-3

• CO2
• CH4
• N-2
• adsorption separation
• H beta
• Na beta

Adsorption isotherms of carbon dioxide (CO2), methane (CH4), and nitrogen (N-2) on H beta and sodium exchanged beta-zeolite (Na beta) were volumetrically measured at 273 and 303 K. The results show that all isotherms were of Brunatier type I and well correlated with Langmuir-Freundlich model. After sodium ions exchange, the adsorption amounts of three adsorbates increased. while the increase magnitude of CO2 adsorption capacity was much higher than that of CH4 and N-2. The selectivities of CO2 over CH4 and CO2 over N-2 enhanced after sodium exchange. Also, the initial beat of adsorption data implied a stronger interaction of CO2 molecules with Na+ ions in Na beta. These results can be attributed to the larger electrostatic interaction of CO2 with extraframework cations in zeolites. However, Na beta showed a decrease in the selectivity of CH4 over N-2, which can be ascribed to the moderate affinity of N-2 with Na beta. The variation of isosteric heats of adsorption as a function of loading indicates that the adsorption of CO2 in Na beta presents an energetically heterogeneous profile. On the contrary, the adsorption of CH4 was found to be essentially homogeneous, which suggests the dispersion interaction between CH4 and lattice oxygen atoms. and such interaction does not depend on the exchangeable cations of zeolite.

• 出版日期2008-12
• 单位南京工业大学; 材料化学工程国家重点实验室