The adsorption behaviors of CO2 and CH4 on new siliceous zeolites JSR and NanJSR (n = 2, 8, 16) were simulated using the Grand Canonical Monte Carlo method. The adsorption isotherms of CO2 became higher with an increase in the Na+ number at a low pressure range (<150 kPa), whereas the isotherms showed a crossover with increasing pressure and the adsorption amount became smaller at a high pressure range (>850 kPa). With an increase in Na+ number, the pore volume decreased as the pore space was occupied by increasing Na+ ions. Additionally, two energy peaks on the interaction energy curves implied that CO2 was adsorbed on two active sites. On the other hand, the adsorption amount of CH4 decreased with an increase in the Na+ number and only one energy peak was observed. Adsorption isotherms were well fitted with the Langmuir and Freundlich equations up to 1000 kPa and the adsorption affinity of CO2 on Na16JSR zeolite was highest. The adsorption capacities of CO2 in the studied zeolites were up to 38 times higher than those of CH4. Diffusion constants of CO2 and CH4 decreased with an increase in the adsorbed amount and Na+ number. Considering the adsorbed amount, adsorption selectivity and affinity, zeolites JSR with a low Na+ number (JSR and Na2JSR) is a good candidate for a pressure swing adsorption in the separation of CO2/CH4 mixture whereas JSR zeolites with high Na+ ratios (Na16JSR and Na8JSR) may be a better selection for a vacuum swing adsorption.
Bibliographical noteFunding Information:
This work was supported by the National Natural Science Foundation of China (21276101, 21106051), the Jiangsu Program for Production, Teaching, and Research (BY2015052-01), the Natural Science Foundation of Jiangsu Universities (16KJA530001), the Foundation of Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials (JSKC13132), the Program for Excellent Youth of Jiangsu Qing-Lan Project, and the Huaian Program for Production, Teaching, and Research (HAC2015028).
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Surfaces and Interfaces