The surface modification of zeolite Y in composite selective layer of hollow fiber membrane for separation of CO2/CH4 mixture

Abstract

This work focused on the fabrication and evaluation of composing hollow fiber mixed matrix membranes (MMMs) incorporated by zeolite Y for CO2/CH4 separation. The effects of surface modification of zeolite Y to improve compatibility of filler and polymer dispersibility of the filler in the polymer matrix on properties and separation performance of the membrane were investigated. A polysulfone (PSF) was used as a support hollow fiber and a selective layer composing of polyether-block-amide (Pebax) and zeolite Y (ZeY) and surface modification of zeolite Y (mo-ZeY) was coated on support. A [3-(2-Aminoethylamino)propyl]trimethoxysilane (AEAPTMS) was used to grafted on surface of pristine zeolite Y. The effects of filler loading at 0-20 wt% on membrane property and separation performance were investigated. The results revealed that the filler started to agglomerate at 10 wt% for ZeY and at 15 wt% for mo-ZeY. However, the aggregated filler cluster still showed fairly good dispersion. In addition, the interfacial gap and void between the disperse phase and the continuous phase of MMMs did not appeared. The addition of ZeY and mo-ZeY from 0 wt% to 5 wt% provided a positive impact on membrane performance because CO2 can diffuse through the filler pores easier than CH4. The decrease in membrane performance was obtained with increasing filler content from 10 wt% to 20 wt% due to polymer rigidified and filler agglomeration that from nonselective path. The optimal condition of filler loading was found to be 5 wt% for both filler. The 5 wt% ZeY/Pebax membrane can improve CO2 permeability and CO2/CH4 selectivity from 27.48 to 45.06 barrers and 10.97 to 19.82, respectively. In the same ways, the 5 wt% mo-ZeY/Pebax membrane can improve CO2 permeability and CO2/CH4 selectivity from 27.48 to 51.72 barrers and 10.97 to 21.53, respectively. The optimal operating conditions were found at 2 bars and 30oC due to it provides highest separation performance. The result showed that at the same filler loading, the mo-ZeY/Pebax provide a better dispersibility and separation performance compared to ZeY/membrane.