Carbon dioxide separation from hydrogen and nitrogen: Facilitated transport in arginine salt–chitosan membranes

Abstract

CO 2-selective membranes that obtain high CO 2 permeabilities accompanied with high CO 2/H 2 and CO 2/N 2 separation factors at industrial temperatures and pressures are applicable to fuel cell operations and flue gas purification. This paper describes the separation of carbon dioxide from a mixed gas stream of hydrogen and nitrogen by a chitosan membrane containing 40 wt% sodium arginate. Continuous membrane separations were done for a feed gas with 10% carbon dioxide, feed gas total pressures of 152 and 507 pa (1.5 and 5 atm), and temperatures ranging from 20 to 150 °C. The addition of arginine salts increases the number of amino groups for facilitated transport of CO 2 and increases the water levels in the arginine salt–chitosan membranes compared to swollen chitosan membranes at the same humidification conditions. At 152 pa (1.5 atm) feed pressure and 110 °C, there are maxima in the carbon dioxide permeabilities (1500 barrers), and the separation factors for CO 2/N 2 (852) and CO 2/H 2 (144). At higher pressure (507 pa (5 atm)), there were no maxima in the carbon dioxide permeabilities or separation factors, and there was less bound water in the membrane.