Preparation and performance assessment of binary and ternary PES-SAPO 34-HMA based gas separation membranes

The effect of low molecular weight additive (LMWA) loading on the gas permeation properties of pure PES and PES/SAPO-34 membranes was investigated. 2-hydroxy 5-methyl aniline (HMA) was selected as LMWA. Membranes were prepared by solvent-evaporation method and annealed above the glass transition temperature (Tg) of PES. They were characterized by single gas permeability measurements of H2, CO2, and CH4 as well as scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The H2/CH4 selectivities of pure PES and SAPO-34/PES membranes were 71.31 and 61.02, respectively. The incorporation of zeolite SAPO-34 to neat PES membranes resulted in higher permeabilities for all gases with slight decrease in CO2/CH4 and H2/CH4 ideal selectivities compared to pure PES membranes. However, PES/SAPO-34/HMA membranes had significantly higher ideal selectivities than pure PES, PES/SAPO-34, and PES/HMA membranes, for example the H2/CH4 selectivity of HMA/SAPO-34/PES membrane was 175.8, which was three times as high as the H2/CH4 selectivity of PES/SAPO-34 membrane. The permeabilities of all the gases through PES/SAPO-34/HMA membranes were also higher than those through PES/HMA membranes. Ternary component membranes revealed better gas permeation performance compared to pure polymeric and binary component membranes.