A water-swollen thin film composite membrane for effective upgrading of raw biogas by methane

Recently, purification of raw biogas has attracted a great attention of research community. Possibility of effective waste utilization for cheap biofuel production has enormous ecological and economical benefits. In this work a water-swollen thin film composite membrane for effective separation of carbon dioxide from methane in biogas is presented. The hydrophilic reverse osmosis membrane creates under water vapor condensing conditions a thin selective separation layer in which dissolved feed gaseous mixture, except methane. Water vapor saturated biogas was brought into a contact with cooled membrane in order to keep the selective skin layer. Sweeping gas N2 is used to keep constant driving force and to control partial water evaporation from the membrane. Under the described experimental conditions was obtained retentate stream containing 95 vol.% of methane.

► The new method for effective biogas purification and methane upgrading is presented. ► The reverse osmosis membrane creates under water vapor condensing conditions a thin selective separation layer. ► The proposed method does not require any purification pretreatment and produces no toxic waste.