CO₂ capture from coalbed methane using membranes: a review

Coalbed methane is an abundant form of natural gas extracted from coal beds. Coalbed methane is viewed as a cleaner energy source versus petroleum and coal combustion because methane extraction, transport and use are more efficient and less polluting. However, coalbed methane contains high amounts of CO₂ that induce solidification during liquefaction. Therefore, CO₂ has to be reduced below 2% to meet the pipeline transportation standards. In addition, CO₂ capture would reduce the amount of gas emissions to the atmosphere, thus mitigating global warming. Here, we review membrane absorption, which is an advanced method for CO₂ capture from coalbed methane, by controlling the gas and liquid phases separately during the operation process. We compare CO₂ removal methods for various coalbed methane sources. Parameters influencing CO₂ removal by membrane absorption are discussed to conclude that CO₂ capture efficiency is improved by increasing the flow rate, temperature, and absorbent concentration, reducing the gas flow rate, and selecting a mixed absorbent. We also explain the principles, processes and applications of CO₂ membrane absorption.