CH₄/CO₂ separation from biogas stream using porous hydrophobic ceramic hollow fiber membrane contactors

Experiments were performed to separate CO₂ from biogas using a ceramic hollow fiber membrane contactor (HFMC). CH₄/CO₂ mixed gas (34.5% CO₂, CH₄ balance) and monoethanolamine (MEA) were used. The influence of operating conditions, such as the gas flow rate, liquid flow rate, L/G ratio, CO₂ partial pressure, and module type, on the CO₂ removal efficiency and CO₂ absorption flux was evaluated. As the gas flow rate increased, the CO₂ removal efficiency decreased, while the CO₂ absorption flux increased. The maximum CO₂ removal efficiency was 96% at a gas flow rate of 0.1Nm³ h⁻¹ while the maximum CO₂ absorption flux was 7.5×10⁻³ mol·m⁻²·s⁻¹ at a gas flow rate of 1Nm³ h⁻¹. Moreover, the CO₂ absorption flux and CO₂ removal efficiency could be increased by more than 20% using the high-flux module.