CO₂ Capture Using A Superhydrophobic Ceramic Membrane Contactor

The greenhouse effect caused by massive emissions of CO2 has drew great attention all over the world. Carbon dioxide capture and storage (CCS) has been examined as one of viable options for mitigating atmospheric CO2 levels due to fossil combustion. At present, most of the commercially available hollow fiber membranes are made from polymeric materials, which suffer from some technical problems. Compared with the polymeric membranes, ceramic membranes show excellent structural, thermal, physical and chemical stability. There has been no report on the use of hydrophobic ceramic hollow fiber membrane for CO2 absorption so far. So it is necessary to study the performance of ceramic hollow fiber membrane for CO2 capture.In this study, FAS was used as a surface modifier to conduct the surface hydrophobic modification. The results of characterization methods show that a chemically bound hydrophobic layer was formed on the surface of ceramic membrane, which has not significant effect on the structure and morphology of the ceramic membrane. The membrane surface was modified from hydrophilicity to superhydrophobicity with a contact angle of 153°.In order to investigate the effects of basic operation parameters on CO2 removal efficiency and mass transfer rate, a ceramic membrane contactor modified by FAS was employed as the absorber and aqueous monoethanolamine (MEA) as the absorbent in the experiments. Under the operating conditions of 5wt% MEA absorbent solution, the ceramic membrane contactor shows a perfect CO2 removal efficiency and mass transfer rate. It demonstrated the feasibility of this technology.Finally, superhydrophobic ceramic (SC) membrane and PP membrane contactors were adopted to research their performances of CO2 capture, self-cleaning and anti-fouling. By comparing the performances of two membrane contactors, the former has better performances on CO2 removal, anti-wetting and anti-fouling. The experimental overall mass transfer coefficient is more close to the theoretical overall mass transfer coefficient (0.94). The SC membrane contactor has a higher CO2 removal efficiency and mass transfer rate. To ensure continuous CO2 removal with high efficiency (above 74%), a method that two SC membrane contactors alternatively operate with periodic drying was proposed. The SC membrane contactor shows great potential in real industrial CO2 post-combustion capture.