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Abstract: A hollow fiber composite membrane was prepared by coating a poly(N,N-dimethylaminoethyl methacrylate)–poly(ethylene glycol methyl ether methyl acrylate) (PDMAEMA–PEGMEMA) skin layer onto a porous polysulfone (PSf) substrate. The influence of fabrication parameters including coating solution concentration and coating times on the permselectivity of the prepared membrane was investigated. For the composite membrane prepared from the optimal fabrication parameter, its CO2 permeance was about 30GPU with CO2/N2 selectivity of 31 at 35°C and 202.65kPa. Moreover, the effects of experimental temperature and pressure on the permselectivity of hollow fiber composite membranes were evaluated. The gas permeance increased with the increase of temperature, which obeyed Arrhenius relation. With the increase of pressure, N2 showed the similar permeance that meant the transport of N2 through membrane followed solution–diffusion mechanism, while for CO2, its permeance underwent a two step change (first increased then decreased) which suggested there might be two transporting models for CO2 (solution–diffusion and facilitated transport). In addition, it was found that water vapor in the feed gas not only caused plasticization, but also enhanced the interaction of CO2 with amino groups in PDMAEMA–PEGMEMA skin layer. Both of the two effects contributed to a higher CO2 permeance compared with the condition that water vapor was absent. [Copyright &y& Elsevier]

Polytetrafluoroethylene (PTFE) is considered as a promising material for membrane contactors due to its intrinsic hydrophobicity and excellent chemical stability. In most published works concerning CO 2 absorption, PTFE hollow fiber membranes with diameter larger than 1.2 mm even 2.0 mm were applied, which lost the advantage of membrane contactor in high specific surface area and also increased the mass transfer resistance. In this study, biogas purification by membrane contactor was systematically investigated based on the smaller-diameter PTFE hollow fibers (0.9 mm) developed recently in our laboratory. CH 4 –CO 2 (40%) mixture was used as simulated biogas, and deionized water was used as absorbent for all tests. The influence of module configuration, liquid flow pattern, membrane microstructure, and gas-liquid flow velocity on CO 2 removal performance were studied in detail. Moreover, the mass transfer resistance and CH 4 recovery rate were also discussed. CO 2 content in purified biogas could be below 3% by adjusting the operating parameters. CO 2 flux and overall mass transfer coefficient (K OV) under experimental conditions ranged from 0.61 × 10−3 to 1.35 × 10−3 mol/(m2. s) and from 1.67 × 10−5 to 6.34 × 10−5 m/s, respectively. Moreover, CO 2 removal performance was stable in an operation of 36 h. PTFE hollow fibers with smaller diameter exhibited preeminent CO 2 removal efficiency, which proved great application potential in biogas upgrading by membrane contactor. [Display omitted] • PTFE hollow fiber (diameter of 0.9 mm) for biogas upgrading by membrane contactor. • Weaving configuration design of membranes significantly improved mass transfer. • Effects of fluid flow pattern and membrane microstructure were also investigated. • Smaller-diameter PTFE membrane contactor exhibited good application potential. [ABSTRACT FROM AUTHOR]

A versatile pilot-scale two-stage membrane plant for CO 2 capture from different simulated exhaust gases was designed and constructed. The capture efficiency was investigated in detail under different operating pressures, humidifier temperatures, and stage-cuts based on the graded CO 2 contents of the initial feed gas (i.e., 14%, 25%, and 35%), which were similar to the typical CO 2 contents of industrial exhaust gas emitted from coal-fired power plants, steel mill/cement plants, and factories associated with high–CO 2 –concentration operations, respectively. When the CO 2 capture rates were 61.3%, 60.7%, and 53.9% in the three cases, the product gas CO 2 purities could reach 78.5%, 87.2%, and 96.3%, respectively. This study also represents the first instance of developing an actual design and layout of a three-stage and three-step membrane plant, which will be built in early 2021 in Nanjing, China, and is expected to achieve the targets of 95% CO 2 product purity and 90% CO 2 capture rate. The experience gained through this study could accelerate the industrial application of membrane technology for CO 2 capture. Image 1 • A versatile pilot-scale two-stage membrane plant was designed and constructed. • It provided a picture of CO 2 capture covering different industrial occasions. • It was the first time to present an actual design and layout of membrane plant. • The well-designed plant had the potential to approach the DOE's capture target. [ABSTRACT FROM AUTHOR]