Selection of top layer materials for gas–liquid membrane contactors

Abstract

Gas-liquid membrane contactors frequently suffer from wetting of the microporous membrane. Stabilization layers at the liquid side of the membrane potentially prevent this wetting. We applied such stabilized membranes to the separation of olefins and paraffins using AgNO 3 solutions as absorption liquid. The stabilization material requires permeation of olefins at minimum counter transport of water. Appropriate selection of the top layer material is crucial in this application. This report describes the selection of potential top layer materials. Dense films of the selected materials were prepared and used to determine ethylene and ethane permeabilities, to perform pervaporation experiments with water and a 3.5M solution of silver nitrate in water, and to determine the swelling behavior of the dense films in water and in a 3.5M silver nitrate solution. Based on the characterization experiments, ethylene propylenediene terpolymer is the most appropriate candidate with the highest potential for application in a gas-liquid membrane contactor for the separation of paraffins and olefins. It has a relatively high olefin permeability (46.4 Barrer) and a corresponding low water vapor permeability and low swelling tendency in a 3.5M silver nitrate solution (1490 Barrer and 0.14 wt %, respectively).

Ammonia based CO2 capture process using hollow fiber membrane contactors

“…It should be stressed that, whereas microporous membranes only offer a limited number of degrees of freedom for differentiating CO 2 and NH 3 mass transfer, a meticulous selection of the dense skin could potentially allow maximizing CO 2 mass transfer while lowering ammonia slip. This target requires designing a composite hollow fiber membrane contactor made of a chemically resistant dense layer showing both [23]: a CO 2 permeability as high as possible, a NH 3 permeability as low as possible,…”

CO2 desorption from rich alkanolamine solution by using membrane vacuum regeneration technology

“…In addition, wetting is a serious problem which will lead to significant increase of the mass transfer resistance due to the introduction of a stagnant liquid layer in the pores of the membrane (Kreulen et al, 1993a). To prevent wetting, surface modification membrane (Koonaphapdeelert et al, 2009;Das et al, 1998;Koonaphapdeelert and Li, 2007) and composite membrane consisting of a porous support and a dense selective top layer (Simioni et al, 2011;Nymeijer et al, 2004;Li and Teo, 1996) were considered. However, these membranes are usually extremely expensive which would increase the capital cost and not appropriate for commercial application in short term.…”

Olefin-Selective Membranes in Gas−Liquid Membrane Contactors for Olefin/Paraffin Separation

“…This is due to unfavorable interactions between the polar, oxygencontaining PEO/PBT polymer and the C 2 hydrocarbons. [11][12][13] The water permeability of potential top layer materials for the separation of paraffins and olefins in a membrane contactor application may be important because it can give an indication of whether undesired humidification of the gas streams in the contactor is likely to occur. The experimentally determined water permeability of PEO/PBT films using a 3.5 M silver nitrate solution as the feed is extremely high compared to the values obtained for EPDM and SPEEK.…”

“…Compared to the hydrophilic PEO/PBT films, EPDM films have a much lower weight increase due to swelling because of the strong hydrophobic character of the hydrocarbon polymer chains. 13 3.2. Composite Membrane and Module Preparation.…”