Progress in the Application of X Zeolite in Adsorption

The application of X zeolite in the areas for producing para-xylene by adsorptive separation, N-2/O-2 separation, etc., was reviewed, and the framework SiO2/Al2O3 molar ratio, the cations and the water content of X zeolite significantly affected its selectivity and capacity. As the active component of para-xylene adsorbent, the X zeolite with a framework SiO2/Al2O3 molar ratio of 2.2-2.4 coupled with cations of Ba2+ and K+, as well as a water content of 4.0%-5.0% exhibited higher para-xylene selectivity. For N-2/O-2 separation, higher N-2 capacity and N-2/O-2 separation factor were achieved when the X zeolite had a framework SiO2/Al2O3 molar ratio of 2.0 coupled with Li+ cations. The introduction of another cation in X zeolite could further increase the N-2/O-2 separation factor, while the adsorption of water, however, could lead to a remarkable decrease of N-2 capacity. Besides, the X zeolite could be used in adsorptive separation of highly pure He and selective adsorption of CO2, CO, CH4, N-2, Ar, and H-2.