New pressure swing adsorption cycles for carbon dioxide sequestration

A rigorous pressure swing adsorption (PSA) process simulator was used to study anew, high temperature PSA cycle, based on the use of a K-promoted HTlc adsorbent and a simple, 4-step, Skarstrom-type, vacuum swing cycle designed to process a typical stack gas effluent at 575 K containing (in vol%) 15% CO2, 75% N-2 and 10% H2O. The effects of the purge-to-feed ratio (gamma), cycle step time (t(s)) (with all four steps of equal time), and pressure ratio (pi(T)) on the process performance was studied in terms of the CO2 recovery (R) and enrichment (E) at a constant throughput theta of 14.4 L STP/hr/kg. R increased with increasing gamma and pi(T) and decreasing t(s), while E increased with increasing t(s) and pi(T) and decreasing gamma. The highest E of 3.9 was obtained at R = 87% and pi(T) = 12, whereas at R = 100% the highest E of 2.6 was obtained at pi(T) = 12. These results are very encouraging and show the potential of a high temperature PSA cycle for CO2 capture.