Separation of CO2 from CH4 by using gas–liquid membrane contacting process

The separation of carbon dioxide (CO2) from methane (CH4) by using a gas–liquid membrane contactor was studied in order to confirm the potential of the process. The experiments were performed in a membrane contactor constructed with 0.2 μm pore size microporous PVDF hollow fibers. Pure water, aqueous sodium hydroxide (NaOH) solution and aqueous monoethanolamine (MEA) solution were employed as the absorbents. Sodium chloride (NaCl) was also used as an additive in the NaOH aqueous solution. The effects of operating parameters such as the gas and liquid velocity, concentration of NaOH solution, absorbent temperature, and NaCl concentration on the CO2 flux were investigated along with the mass transfer analysis of the process. In addition, the impacts of the flow pattern and the membrane module packing density as well as the long-term performance were also investigated, aiming to obtain a full picture and a deep insight on the system.