Separation of ethylene and ethane using Co-Gallate pellets in a vacuum swing adsorption process

This work reports a vacuum swing adsorption (VSA) process that utilizes Co-gallate pellets to produce high-purity ethylene. The process is tested on two feed streams generated from the pyrolysis of naphtha and steam cracking of ethane, respectively. The VSA cycle consists of four steps: pressurization, adsorption, replacement with ethylene product and blowdown. A cyclic steady state (CSS) is reached for every test condition, verified by checking the profiles of column pressure, gas composition, and solid loading, which remain constant for ten subsequent cycles. Through analysis of the independent decision variables that affect the performance of the 80/ 20 (v/v) ethylene/ethane mixture separation, we identify desorption pressure and the replacement flowrate to feed flowrate ratio as the most significant factors. By optimizing these variables, we achieve an exceptional purity of 99.90% for ethylene with a 46.45% recovery and a productivity of 1.05 mol kg-1 per cycle. The Co-gallate adsorbent has a high affinity for ethylene and a low diffusion limitation, thus demonstrating superior potential for industrial ethylene/ethane separation compared to zeolite 4A and Ag+-Amberlyst 35.