Performance evaluation of clinoptilolite and 13X zeolites in CO2 separation from CO2/CH4 mixture

In this study, the adsorption performance of clinoptilolite and 13X zeolites as adsorbent was examined to remove CO2 from CO2/CH4 mixture. The adsorption experiments of CO2 and CH(4)on 13X and clinoptilolite zeolites were conducted at 277, 290 and 310 K for pressures up to 10 bar. The adsorption capacity of CO2 on 13X zeolite was higher than clinoptilolite zeolite. The ideal selectivity of CO2/CH4 for 13X and clinoptilolite zeolites are 8.47 and 5.63 at 277 K and 1 bar, respectively. The adsorption heats for the two gases on adsorbents were calculated using the van't Hoff equation. The values of adsorption heats of CO2 and CH4 for 13X zeolite are 34.65 and 15.43 kJ/mol, whereas adsorption heats of CO2 and CH4 on clinoptilolite zeolite are 21.03 and 11.62 kJ/mol, respectively. The highest adsorption heat was obtained for adsorption of CO2 on 13X zeolite, which refers to the strong adsorption of CO2 on the surface of this zeolite. The extended Langmuir and Sips models were utilized to correlate the experimental data, and Sips model showed a better fit of the data. According to the results of this study, it was found that the 13X zeolite is a more appropriate adsorbent for removing carbon dioxide from natural gas, compared with clinoptilolite. (C) 2015 Elsevier B.V. All rights reserved.