CO2 -Selective Thin-Film Polymer Composite Membranes: Improvement of Thermal Stability and Role of Amine Carriers
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The overall objective of this work is to develop a simple process to separate carbon dioxide (CO2) from a fossil fuel combustion gases using thin-film composite dense polymeric membrane containing amine carrier. Main focus of this project is to improve the membrane permeability along with high CO2/N2 selectivity at elevated temperature (> 100oC) against low pressure difference ( is around 1 atm) which is essentially close to the flue gas emitting condition from thermal power plant. Poly(vinyl alcohol) (PVA) was used as basic polymeric material due to its excellent hydrophilic nature and good film-forming ability. Thermal stability of PVA has been improved by crosslinking with formaldehyde (HCHO) and polymer blending with thermally stable polymer like polyvinylpyrrolidone (PVP). The optimum degree of crosslinking of PVA with formaldehyde was 60 mole%. The PVA/PVP weight percent ratio was chosen as 1:0.2. Different combinations of single and blended amines were introduced into the polymer hydrogel to enhance the CO2 transport property through the membrane. These amines were polyethyleneimine (PEI), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), poly(allylamine) (PAA) and 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD). The synthesized dry membranes were characterized with TGA, DSC, FTIR and XRD. All the characterizations were done for active layer only which was found to be optically transparent to visible light and mechanically stable to be handled.
Supervisor: Bishnupada Mandal