| The main components of coal-bed gas are methane and nitrogen, while the main components of landfill gas are methane and carbon dioxide. The pressure swing adsorption (PSA) has the superiority in dealing with these cases where the flow rate is not large, but high selectivity adsorbents are unavailable. The adsorbents, used for the two systems metioned above (methane/nitrogen and methane/carbon dioxide), were investigated to increase selectivity. The N2 selectivity adsorbents (natural clinoptilolite and ETS-4 sieves) have a promising future as CH4 can be obtained directly as product gas by PSA.The clinoptilolite(1#) produced in Jilin was the best one screened in the four kinds obtained from different areas of China. Treated at different temperature, The clinoptilolite(1#) was methane-preferred when calcined at 100℃, but it was nitrogen-preferred when calcined at 280℃. To improve its selectivity, different ion-exchange clinoptilolites were studied. Na-clinoptilolite exchanged at room temperature for three times was the best,it was nitrogen-preferred,and it's N2 and CH4 adsorption amount ratio is 4.37 at 1 atm. The adsorption amount of N2 and CH4 on Ca, Mg, Li, K, Sr and NH4- clinoptilolite was similar. ETS-4 sieves are synthesized, and their structures are the same with the literatures by its XRD and SEM results. Modified it with Sr, and the N2 and CH4 adsorption amount on Sr-ETS-4 is not so good as that of Na-clinoptilolite, but the adsorption amount ratio of N2 and CH4 is higher than Na-clinoptilolite.If mesoporous molecular sieves are modified by CO2 absorbents in the CH4/N2 separation system, the mesopore and absorption were combined and the adsorption capacity of CO2 can be enhanced, and it would be a CO2 capture adsorbent. Firstly, SBA-15 mesoporous molecular sieve was synthesized and modified by different CO2 absorbents such as DIPA, MDEA, NMP, DGDE, TEP, PC. The structures of SBA-15 before and after modified all remain highly ordered hexagonal structure. The SBA-15 modified by DIPA has a maximum selective separation coefficient for CO2/CH4. Methane adsorbed on SBA-15 modified by DIPA could be regenerated completely, while the adsorption capability of carbon dioxide decreased and reached stable after 6 stability tests, and the separation coefficient of CO2/CH4 was 15.5. The carbon dioxide adsorption-desorption performance of DIPA modified SBA-15 were studied on temperature change. High temperature is benefit to adsorption and low temperature is advantageous to desorption, and the comprehensive performance for CO2/CH4 separation is best at 45℃.
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