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.

This work deals with the study of chemical stability and the general behavior of hydrophobic glassy polymers with an excess of free volume fraction, such as poly[1-(trimethylsylil)-1-propyne] (PTMSP), poly[1-(trimethylgermil)-1-propyne] (PTMGP) and poly[4-methyl-2-pentyne] (PMP). The dense membranes based on these polymers have been tested at conditions which are typical for the regeneration of CO₂ absorbent liquids (e.g. CCS). As expected, these membrane materials initially showed a decline of the gas permeability (N₂, O₂ and CO₂) at 100°C, which is mainly attributed to the relaxation of the free volume structure. The transport parameters then leveled off and a slight decreasing of the gas transport parameters in time was observed. In contrast to previous published data, no chemical degradation of those polymers, in particular the absence of CO and C-O groups, was detected by FTIR spectroscopy, even after exposure to air at 150°C. In addition, long-term contact with different kinds of physical and chemical absorbent liquids at 100°C did not lead to changes in the chemical structure and macroscopic properties of those polymers. It was shown that absorption liquids like water or alkanolamines can be regenerated by pressure and temperature swing (Δp_m=40bar, T=100°C) in gas-liquid contactors based on PTMSP, PTMGP and PMP.