Removal of C 2 H 4 from a CO 2 Stream by Adsorption: A Study in Combination of ab Initio Calculation and Experimental Approach

Removal of C 2 H 4 from a CO 2 stream is very important in ultrapurification of CO 2 for its application and utilization. However, it is difficult to remove C 2 H 4 completely from a CO 2 stream via conventional cryogenic distillation because the volatility of C 2 H 4 is similar to that of CO 2 . Another choice is the catalytic combustion method, but it is an energy-inefficient process, especially when it is coupled with the cryogenic distillation. Selective adsorption for removing C 2 H 4 might be a promising alternative one. A great effort has been made in olefin/paraffin separation and recovery of olefin. There are, however, few reports about the removal of a trace of C 2 H 4 from a CO 2 stream. In this study, ab initio calculations have been conducted to screen the potential adsorbents. We found that AgNO 3 exhibits a much higher adsorption affinity for C 2 H 4 through a π-complexation interaction, indicating that the AgNO 3 -modified zeolite might be a promising adsorbent. Furthermore, the AgNO 3 -modified NaY zeolite was prepared, and its adsorption performance was tested. We showed that the AgNO 3 /NaY is able to remove C 2 H 4 from a CO 2 stream to less than 1 ppmv with an adsorption capacity of 13 mL/g at a concentration level of 1030 ppmv C 2 H 4 . The results also imply that the ab initio calculations and the developed adsorption models in the present study are useful for designing the novel adsorbents.