Highly permeable novel PDMS coated asymmetric polyethersulfone membranes loaded with SAPO-34 zeoilte for carbon dioxide separation

Novel asymmetric polyethersulfone membranes loaded with SAPO-34 particles were prepared using phase inversion technique and then surface coated with PDMS using spin coating method. The mixed matrix membranes were then characterized by FTIR, TGA, SEM-EDX and gas permeation analysis. Effect of SAPO-34 loading along with operating pressure was also analyzed on gas permeation properties of both coated and uncoated membranes. SAPO-34 loading resulted in improvement of permeability of all the gases without much decrease in CO2 ideal selectivity with respect to methane and nitrogen whereas PDMS coating resulted in improvement of ideal selectivity of CO2 at the expense of decrease of permeance of all the gases. It was found that PDMS coated PES membrane, loaded with 30 wt.% SAPO-34, having thickness of 45 mu m, demonstrated high CO2 permeance of 641.77 GPU, CO2/CH4 ideal selectivity of 4.45 and CO2/N-2 ideal selectivity of 12.45, respectively at 20 bar and 25 degrees C. It was found that the performance of this membrane crossed the Robeson upper bound limit 2008 for CO2/N-2 separation whereas for CO2/CH4 separation it crossed the previous upper bound limit 1991. Finally, the performance of this membrane was also analyzed under mixed gas conditions for CO2/CH4 separation at high pressure.