| Separation and reclaim of CO2 is one of the most important subjects on energy, resource and environment in 21 century. Fixed carrier membrane for CO2 separation is a new research field in which both the development of membrane material and the improvement of membrane preparation technique are urgent. This study made attempts to develop fixed carrier membranes for CO2 removal prepared by interfacial polymerization (IP).Five kinds of fixed carrier composite membranes were developed by IP from aqueous phase to organic phase, with diethylenetriamine (DETA), trimethylene tetramine (TETA), tetraethyleneamine (TEPA), polyethylene polyamide (PEPA) and polyethylenimine (PEI) as monomers or prepolymer of aqueous phase, trimesoyl chloride (TMC) as monomer of organic phase, polysulfone (PS) or polyethersulfone (PES) ultrafiltration membranes as supports. Several techniques were employed to characterize the structure of the membranes. The permselectivities of the membranes were measured with CO2/CH4 as well as CO2/N2. Influence of various parameters on membrane structure and performance were studied. The results show that these membranes contain a lot of amine groups, the IP layers of the composite membranes are dense, rough and very thin, and the adhesion between the IP layer and the porous support is good due to penetration of the IP layer into the porous support. Composite membranes with TETA as amine monomer have good performance with 10-15min heat-treatment at 65-70oC, 2-2.8wt% TETA concentration, 0.2-1.2wt% TMC concentration, 2-10min soaking in TETA solution, 3-4min IP time, more than 0.4wt% acid acceptor concentration of Na2CO3, NaOH or TEA. With amine chain longer, gas permeance of the membranes with various amines increases and the selectivity of the membranes decreases. Generally, with feed pressure increasing or temperature decreasing, CH4 or N2 permeance increases and CO2 permeance decreases which result in a decrease in CO2/CH4 or CO2/N2 selectivity.These composite membranes have excellent comprehensive performances including permselectivties and pressure stabilities, which are better than that of other fixed carrier membranes reported in literatures. For example, for feed gas containing 10vol% CO2 and 90vol% CH4, at 30oC and 1.1atm of feed gas pressure ,DETA-TMC/PS, TETA-TMC/PS, TEPA-TMC/PS and PEPA-TMC/PS composite membranes display CO2 permeance of 5.85×10-6, 1.47×10-5, 2.38×10-5 and 3.18×10-5 cm3(STP)cm-2s-1cmHg-1 and CO2/CH4 selectivity of 124, 96, 76 and 64. At 10.6atm, 10.4atm, 10.2atm and 9.9 atm of feed pressure,these membranes have CO2 permeance of 4.86×10-6, 9.20×10-6, 1.34×10-5 and 1.65×10-5 cm3(STP)cm-2s-1cmHg-1 and CO2/CH4 selectivity of 56, 42, 35 and 31. These membranes have better permselectivity for feed gas containing 20vol% CO2 and 80vol% N2. At 1.1atm of feed pressure, PEI-TMC/PS composite membrane has a CO2 permeance of 3.13×10-5 cm3(STP)cm-2s-1cmHg-1 and CO2/CH4 selectivity of 81, at 10.9atm of feed pressure, this membrane has a CO2 permeance of 2.34×10-5cm3(STP)cm-2s-1cmHg-1 and CO2/CH4 selectivity of 37.TETA-TMC/PES fixed carrier membranes were prepared by IP from organic phase to aqueous phase. The method of IP methods from aqueous phase to organic phase and the method of IP from organic phase to aqueous phase, and the corresponding membrane structure and performance were compared. The results show that the method of IP from aqueous phase to organic phase is more complex, and the composite membranes prepared by this method present rougher surface, thinner IP layer, and better permselectivity.
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