Facilitated transport of CO2 through liquid membrane accompanied by permeation of carrier solution

Abstract

The effect of convective flow of a carrier solution through a facilitated transport membrane on the CO2 permeation behavior was investigated using diethanolamine (DEA) as a carrier of CO2. A dead-end type filtration cell, equipped with an ultrafiltration membrane, was used as a gas permeation cell. A carrier solution was supplied to the feed side (high pressure side) of the cell and was allowed to permeate to the receiving side (low pressure side) and was circulated between the receiving and the feed side by a pump. The feed gas was a mixture of CO2 and CH4. The convective flow of the carrier solution through the membrane enhanced the gas permeance. For example, the CO2 permeance, RCO2, increased with increasing the volumetric permeation flux of the carrier solution u and when u was 1.9×10−5 m s−1 and the CO2 partial pressure was 4.0 kPa, RCO2 was 6.23×10−5 mol m−2 s−1 kPa−1. This value was about ten times that at u=0 with no convective flow of the carrier solution across the membrane. The selectivity of CO2 over CH4 was as high as 1970. This type of membrane was very stable during the experiments for more than 2 months.