(709b) Carbon Monoxide Isotope Separation by Pressure Swing Adsorption

A simulation study was carried out for the enrichment and recovery of the 14CO isotope from a 14CO/13CO/12CO mixture of CO isotopes using a zeolite adsorbent and a 3-bed 3-step PSA process. Two different cycle configurations were chosen to evaluate the periodic state performance, all with feed pressurization/feed (FP/F), heavy reflux (HR) and countercurrent depressurization (CnD) steps. In these simulations, the effects of various process parameters such as the reflux ratio, cycle time, feed flow rate and valve coefficient on the 14CO enrichment and recovery were investigated. The feed concentration was fixed and contained 1 ppm 14CO and 1 vol% 13CO in a balance of 12CO.

Under total reflux one of the 3-bed 3-step PSA cycle configurations was able to attain an average 14CO enrichment of over 153 for a particular set of operating conditions. After relaxing the total reflux condition, the same PSA cycle configuration still achieved a 14CO enrichment of 19 ppm with 97% recovery. This was the best performance obtained over a wide range of operating conditions. Overall, this study provided significant insight toward the design and development of a more efficient PSA process for the enrichment and recovery of 14CO for a CO isotope mixture.