Gas–liquid membrane contactor for ethylene/ethane separation by aqueous silver nitrate solution

• We used PVDF membrane contactor for absorption of ethylene from ethylene/ethane gas.
• Silver nitrate is used as absorbent and the carrier liquid.
• We developed a comprehensive mathematical model to describe the process.
• The effect of silver nitrate concentration and inlet liquid rate on separation was studied.
• The model predictions were in good agreement with experimental data.

Separation of light olefin from paraffin having the same carbon number is one of the most energy intensive separations in petrochemical processes, which uses very long distillation columns with very high number of trays. This is attributed to the very small differences in the relative volatilities. The purpose of this work is to study the absorption performance of a home-made PVDF hollow fiber membrane fabricated using thermally induced phase separation method. Separation of ethylene from an ethylene–ethane gas mixture, using a hollow fiber membrane based absorption–desorption system with aqueous silver nitrate as absorption solvent, and to enhance separation process with a purchased polypropylene hollow fiber membrane module used for stripping purposes. Experiments on the absorption of ethylene from ethylene–ethane mixture, into silver nitrate solutions were performed. The effects of initial ethylene concentration in feed gas, silver nitrate concentration in the inlet solvent, liquid and gas flow rates were investigated. Results reveal that ethylene/ethane separation factor increases with silver nitrate concentration and liquid flow rates. A two dimensional mathematical model was developed for this purpose. Model predictions were validated with experimental data. Model predictions were in good agreement with experimental results.