Gas/liquid membrane contactors based on disubstituted polyacetylene for CO₂ absorption liquid regeneration at high pressure and temperature

Abstract

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 (Δpm=40bar, T=100°C) in gas-liquid contactors based on PTMSP, PTMGP and PMP.