High-throughput CO2 capture for biogas purification using monoethanolamine in a microtube contactor

Abstract

Abstract The utilization of biogas is somewhat limited by its composition especially CO2. The CO2 content in biogas can be substantially reduced via chemical absorption. In this work, the absorption performance of CO2 removal from biogas using aqueous monoethanolamine (MEA) in a T-type microchannel (0.5 × 0.5 × 60 mm3) was experimentally investigated. The effects of operating parameters including MEA-to-CO2 molar ratio, temperature, pressure, and flow rate of MEA solution were studied in terms of main and interaction effects via statistical analysis. Temperature and MEA-to-CO2 molar ratio showed relatively strong influence on both %absorption and the liquid-side volumetric mass transfer coefficient. A positive confounding effect between these two parameters was also present. Hence, high temperature and high molar ratio resulted in high performance CO2 removal from biogas. Methane purity of 90% was obtained with the molar ratio of 1.8 at 50 °C. The kLa of 517 s−1 was achieved at the MEA-to-CO2 molar ratio of 5:1, 50 °C, 2 bar, and 3 mL/min of the MEA solution. In addition, the absorption flux of CO2 in MEA solution, overall mass transfer coefficient, and kinetic rate constant were evaluated to interpret the experimental results.