Experimental Investigation of Adsorption and CO2/CH4 Separation Properties of 13X and JLOX-500 Zeolites during the Purification of Liquefied Natural Gas

Efficient adsorbents are critical to the purification of liquefied natural gas (LNG) by the adsorption method. In this study, the physiochemical properties of JLOX-500 and 13X were examined. JLOX-500 with more Al content had a more compact unit cell, a larger surface area and pore volume, a smaller average pore size, and more microchannels on the surface than 13X. The separation performance of the two adsorbents was evaluated by the adsorption experiment. The CO2 adsorption capacity of JLOX-500 was higher than that of 13X, while the equilibrium and ideal selectivity and separation factor of CO2/CH4 were also larger for JLOX-500. Especially in dynamic adsorption, the CO2 adsorption capacities at 50 ppm of the gas mixture at the outlet were 3.46 and 1.64 mmol/g for JLOX-500 and 13X, respectively. The adsorption heats of CO2 and CH4 on JLOX-500 were 40.50 and 18.77 kJ/mol, whereas these values were 31.49 and 18.50 kJ/mol for 13X, respectively. A better separation performance for JLOX-500 was observed because of fewer binders and a lower Si/Al ratio (1.34). The Toth adsorption isotherm model described best the experimental data. According to the results of this study, JLOX-500 was a more efficient adsorbent used in purification for LNG production at high pressure with low CO2 concentration.