CH 4 /N 2 Adsorptive Separation on Zeolite X/AC Composites

• Published in: Journal of chemistry 2019-01, Vol.2019, p.1-9
• Main Authors: Xue, Cai Long, Cheng, Wen Ping, Hao, Wen Ming, Ma, Jing Hong, Li, Rui Feng
• Format: Article
• Language: English
• ISSN: 2090-9063; 2090-9071
• DOI: 10.1155/2019/2078360

A series of zeolite X/activated carbon (AC) composites were prepared from the same starting materials at various activation time. The corresponding modified samples were obtained by being treated with diluted NH 4 Cl solution. The relationship between porosity development, surface properties, and CH 4 /N 2 adsorption performance was investigated. The increase of micropore volume is beneficial to the improvement of CH 4 and N 2 adsorption capacity, but more sensitive for CH 4 . In addition, the polar functional groups of zeolite X/AC composites may enhance CH 4 adsorption capacity. More importantly, both developing micropore structure and surface modification contributed to enhance the adsorption selectivity α CH 4 / N 2 . As the optimum sample of these studies, HZAC(24) showed CH 4 adsorption capacity of 17.3 cm 3 /g and the highest adsorption selectivity α CH 4 / N 2 of 3.4. The CH 4 and N 2 adsorption isotherms of all samples can be well fitted by the Langmuir–Freundlich model. HZAC(24) showed an excellent cyclability of adsorption/desorption of CH 4 with a neglectable capacity loss after subsequent cycles. Moreover, HZAC(24) displayed relatively rapid adsorption kinetics. These properties of zeolite X/AC composites are essential for the adsorptive separation of CH 4 from N 2 in the pressure swing adsorption (PSA) process.