Experiment and simulation for separating CO2/N2 by dual-reflux pressure swing adsorption process

•Experimental verification of separating CO2/N2 using a commercial silica gel by DR-PSA process.•Mathematical model and simulation of the DR-PSA process.•Effective results achieved of the DR-PSA process with high CO2/N2 purity and recovery.

A dual-reflux pressure swing adsorption (DR PSA) process with two adsorption beds and six steps was employed for recovering two products simultaneously with a high purity and high recovery efficiency. With silica gel as adsorbent, the feed gas (15% CO2/85% N2) was separated at 299.65 K and 200 kPa by the DR PSA process. Adsorption isotherms of CO2 and N2 on silica gel were measured and fitted by the extended Langmuir model. The process was then simulated with a commercial software, Aspen Adsorption. The simulation results revealed that feed position, method of equalizing-pressure and light component reflux flow rate would affect the performance in terms of purity and recovery significantly. The efficiency and feasibility of the DR PSA process were evaluated by the experiment and results showed that 99.62% of CO2 could be recovered with purity of 99.18% via DR PSA process meanwhile light product N2 could be enriched to 99.64% with recovery of 99.56% under optimal operating conditions. Overall, the DR PSA process is promising for separating a N2/CO2 mixture and producing gases with a high purity and recovery efficiency.