Amine-based solvents regeneration in gas-liquid membrane contactor based on asymmetric PVTMS

Asymmetric flat-sheet membranes made of poly(vinyltrimethylsilane) (PVTMS) were studied for the regeneration of amine-based absorption solvents in a membrane gas-liquid contactor at 100°C. It was shown that PVTMS membrane possesses good mechanical and chemical stability in contact with 4 M monoethanolamine (MEA) and 2 M potassium taurate (PT) solution at 100°C for 250 hours. No liquid penetration through PVTMS was observed during 6 days of continuous testing at a liquid overpressure of 0.55 bar. Storing of PVTMS at 100°C in contact with air for a period of 3 months did not lead to dramatic changes in membrane gas permeability. Membrane gas desorption experiments showed that degradation of loaded MEA leads to membrane fouling, resulting in a decline of membrane performance within 6 days. However, membrane gas desorption experiments with loaded potassium taurate solution did not lead to any noticeable changes of the membrane, and, hence, stable performance of the PVTMS based membrane was observed. Comparing a porous PTFE membrane with an asymmetric PVTMS with dense selective layer shows that the solvent evaporation is at least a factor of 20 lower for the PVTMS membrane; while both porous and non-porous membranes exhibit comparable CO₂ flux indicating that overall resistance of desorption process is mainly governed by the reverse chemical reactions and mass-transfer resistance in the liquid phase.