(419af) The Preparation of Sulfonated Poly(ether ether ketone) Membranes and Application for CO2/CH4 Separation

Sulfonated poly(ether ether ketone)(SPEEK) with sulfonic acid group(–SO₃H) and ether bond(–O–) functional groups have special effect toward CO₂ molecular. In this paper, SPEEK membranes with different degrees of sulfonation (DS) were prepared by post-sulfonation and used for CO₂/CH₄ gas mixture separation. The prepared membranes were characterized by FTIR, TGA, PALS, water content. The results indicate that the weight loss of SPEEK membranes and the content of free water in membrane increased with increasing DS of membranes. Gas permeation experiments indicate that the permeation flux of CO₂ decreased with increasing DS of membranes, separation factor increased with the DS of membrane from 44% to 57%, then decreased with the DS of membrane from 57% to 80%. The membrane with DS of 57% exhibited the highest CO₂ permeability (101 GPU) and separation factor 904. There are two mainly reasons for this: The free water in membrane combined with CO₂ to form HCO₃^- , then CO₂ transport in this way through the membrane. In addition, the hydrophilic –SO₃H on the benzene ring combined with the water surround and form a water channel, the CO₂ molecular transporting through the channel, result in the improving of separation performance.