The problem of regeneration of a carbon dioxide physical absorbent in gas-liquid membrane contactor has been addressed using water as the absorbent. An analytical solution for the mass transfer equation has been obtained with taking into account not only axial, but also radial diffusion of the solute in the liquid flow and thereby significantly extending the area of applicability of the solution. The kinetics of carbon dioxide desorption from aqueous solutions has been described for the membrane contactor based on asymmetric gas separation membrane made of polyvinyltrimethylsilane (PVTMS). It has been shown that the model agrees well with experimental data for different pressures of water saturation with carbon dioxide and desorption temperatures.@en

This work covers the development of robust and stable in time poly[1-(trimethylsilyl)-1-propyne] (PTMSP) thin film composite (TFC) membranes with high CO2 permeance for its application in high pressure/temperature gas-liquid membrane contactors used for amine-based solvents regeneration. For the first time, a novel technique of two-layers coating was proposed and successfully implemented to apply thin top-layer on microfiltration support by adjusting PTMSP solubility in organic solvents. By using different catalytic systems such as NbCl5 and TaCl5/TIBA, it was possible to synthesize two polymer samples ("PTMSP-Nb" and "PTMSP-Ta"), which are insoluble and soluble in hexane, respectively. The first intermediate layer made of "PTMSP-Nb" was cast on the microfiltration porous support from a toluene solution in order to form a PTMSP-coated porous support. The solution of "PTMSP-Ta" in n-hexane was used for subsequent formation of a thin defect-free selective layer (second layer). By using two commercial polymeric (MFFK-1) and metal-ceramic (MC) supports with high surface porosity of 85% and 60%, respectively, it was possible to fabricate the tailor-made TFC membranes "PTMSP/MFFK" (top-layer - 0.5μm) and "PTMSP/MC" (top-layer - 1.2μm) with an initial CO2 permeance of 50 and 36.3m3(STP)/(m2hbar), respectively, and CO2/N2 selectivity of 3.5. A preliminary conditioning of the PTMSP/MC membrane at 100°C for 100h in air was applied for the accelerated relaxation of PTMSP top layer. The resulting robust PTMSP/MC TFC membranes still provided a high CO2 permeance of 1.6m3(STP)/(m2hbar) (~600GPU) without a noticeable decline of membrane performance within the long-term gas permeation testing (at least 250h) at 100°C. The PTMSP/MC membranes were further successfully utilized in HPT MGD for regeneration of 50wt% methyldiethanolamine (MDEA) at elevated temperature (100°C) and pressures (up to 30bar). A stable TFC membrane performance was demonstrated and no solvent leakage through the membranes was observed.@en