Separation and enrichment of carbon dioxide by capillary membrane module with permeation of carrier solution

Abstract

Abstract A novel facilitated transport membrane for gas separation using a capillary membrane module is proposed in which a carrier solution is forced to permeate the membrane. Both a feed gas and a carrier solution are supplied to the lumen side (high pressure side, feed side) of the capillary ultrafiltration membrane and flow upward. Most of the carrier solution which contains dissolved solute gas, CO 2 in the present case, permeates the membrane to the permeate side (low pressure side, shell side), where the solution liberates dissolved gas to form a lean solution. The lean solution is circulated to the lumen side. This type of capillary membrane module was applied to the separation of CO 2 from model flue gases consisting of CO 2 and N 2 . Monoethanolamine (MEA), diethanolamine (DEA) and 2-amino-2-methyl-1-propanol (AMP) were used as carriers or absorbents of CO 2 . The feed side pressure was atmospheric and the permeate side was evacuated at about 10 kPa. CO 2 in the feed gas was successfully concentrated from 5–15% to more than 98%. The CO 2 permeance was as high as 2.7×10 −4 mol m −2 s −1 kPa −1 (8.0×10 −4 cm 3 cm −2 s −1 cmHg −1 ) when the CO 2 mole fraction in the feed was 0.1 and temperature was 333 K. The selectivity of CO 2 over N 2 was in the range from 430 to 1790. The membrane was very stable over a discontinuous one-month testing period.