Influence of heat-treatment on CO2 separation performance of novel fixed carrier composite membranes prepared by interfacial polymerization

Novel fixed carrier composite membranes were developed by interfacial polymerization with water-soluble trimethylene tetramine (TETA) and hexane-soluble trimesoyl chloride (TMC) on polyethersulfone (PES) supports. A series of the composite membranes were prepared by adopting various heat-treatment time or temperature. Scanning electron microscope (SEM) pictures show that the surface of these membranes is covered with a honeycomb-like structure and the thickness of the skin layers is about 0.2 μm. The separation performance was tested with CO2/CH4 mixed gas (10/90 by volume) at various feed pressure. The results show that heat-treatment is a successful way in stabilizing membrane performance with pressure. The membrane heat-treated at 65 °C for 15 min had a CO2 permeance of 1.33 × 10−5 cm3 (STP) cm−2 s−1 cmHg−1 and CO2/CH4 selectivity of 94.1 at feed pressure of 1.1 atm. At 5 atm feed pressure, this membrane had a CO2 permeance of 1.28 × 10−5 cm3 (STP) cm−2 s−1 cmHg−1 and CO2/CH4 selectivity of 40.5. The optimum heat-treatment conditions were 65–70 °C and 10–15 min.