Swelling reduction of polyvinylidenefluoride hollow fiber membrane incorporated with silicoaluminophosphate-34 zeotype filler for membrane gas absorption

Abstract

CO2 gas absorption is important in fuel purification and carbon capture. By incorporating a porous membrane with a large surface area in membrane gas absorption (MGA) system, the CO2 transfer between feed gas and liquid absorbent can be greatly improved. However, the absorption flux usually drops in the long-term operation due to membrane wetting by the common liquid absorbent, amine. Membrane wetting can lead to membrane swelling which induce the growth of mass transfer resistance. In this work, silicoaluminophosphate-34 (SAPO-34) zeolite was incorporated into polyvinylidene fluoride (PVDF) hollow fiber membrane to reduce flux decline caused by membrane swelling. The membrane porosity and pore size increased with increasing SAPO-34 loading. Nevertheless, significant changes in water contact angle or liquid entry pressure were not shown. PVDF hollow fiber membrane incorporated with 3 wt% of SAPO-34 showed slightly higher CO2 absorption flux to PVDF hollow fiber membrane in MGA with distilled water as the absorbent. However, the CO2 absorption flux of this PVDF/SAPO-34 membrane was greatly improved of about 140 % higher than the CO2 absorption flux of the neat membrane when diethanolamine was used as the absorption. The CO2 absorption flux of PVDF hollow fiber membrane dropped about 60 % after 96 hours. Although these membranes showed a similar water contact angle after being wetted by water or amine, they swelled differently. PVDF hollow fiber membrane swelled nearly 71.0 % after being wetted by amine, but only swelled about 2 % after being wetted by water. The incorporation of SAPO-34 into PVDF hollow fiber membrane reduced swelling by amine, down to 47.7 %. The swelling reduction could be a major cause of absorption improvement shown by PVDF/SAPO-34 hollow fiber membrane in MGA using diethanolamine.