抄録
A novel facilitated transport membrane module for gas separation is proposed in which a carrier solution is forced to permeate hollow fiber membranes. Both a feed gas and a carrier solution are supplied to the lumen side (high pressure side, feed side) of a hollow fiber ultrafiltration membrane module and flow upward. The carrier solution, which contains dissolved gas, permeates the membrane to the shell side (low pressure side, permeate side), where the solution liberates dissolved gas to become a lean solution, and it is recycled to the lumen side. It was confirmed by the experiment on the CO2/N2 separation using water as absorbent that the efficiency of this membrane system is very high. This membrane system was applied to the separation and concentration of CO2 in a model flue gas consisting of CO2 and N2 using various amines as carriers. The feed side pressure was about 1 atm and the permeate side pressure was about 0.1 atm. CO2 in the feed gas was successfully enriched from 1.5-15 % to 98.5-99.8% by one-stage membrane separation. The CO2 permeance and the CO2/N2 selectivity were as high as 4.1x10-4 mol m-2 s-1 kPa-1 and 4800, respectively, when the CO2 mole fraction in the feed was 0.1. The energy required for CO2 separation was much lower those by a polymeric membrane process and a conventional gas absorption process consisting of absorption and stripping column. The present membrane system was also applied to the separation and concentration of C2H4 in a C2H4/C2H6 mixture using AgNO3 as the carrier of C2H4. The feed gas was supplied to the module at high pressures (<500kPa) and the permeate side was atmospheric. Ethylene could be enriched from 80% to 99.8%. The membrane modules were stable over a discontinuous 2-4 month testing period.
