CH4/N2 separation on methane molecules grade diameter channel molecular sieves with a CHA-type structure

Samples of methane molecules grade diameter channel CHA-type molecular sieves (Chabazite-K, SAPO-34 and SSZ-13) were investigated using the adsorption separation of CH4/N2 mixtures. The isotherms recorded for CH4 and N-2 follow a typical type-I behavior, which were fitted well with the Sips model (R-2 > 0.999) and the selectivity was calculated using IAST theory. The results reveal that Chabazite-K has the highest selectivity (S-CH4/N2 = 5.5). SSZ-13 has the largest capacity, which can adsorb up to a maximum of 30.957 cm(3).g(-1) (SIP) of CH4, due to it having the largest pore volume and surface area, but the lowest selectivity (S-CH4/N2 = 2.5). From the breakthrough test, we can condude that SSZ-13 may be a suitable candidate for the recovery of CH4 from low concentration methane (CH4 < 20%) based on its larger pore volume and higher CH(4 )capacity. Chabazite-K is more suited to the separation of high concentration methane (CH4 > 50%) due to its higher selectivity. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.