High-quality silicalite-1/PVA mixed matrix membrane for efficient pervaporation separation of xylene isomers

Membrane-based pervaporation process is the most time- and energy-saving method for the separation of xylene isomers. However, developing easily prepared membrane with a high separation factor still remains a significant challenge. Herein, the silicalite-1/polyvinyl alcohol (PVA) mixed matrix membrane (MMM) (SPMMM) with enhanced xylene isomers pervaporation separation performance was successfully fabricated via solution scraping method. The compactness and compatibility of the SPMMM were effectively tuned by optimizing the zeolite content and selecting appropriate cross-linker. Results showed that the SPMMM with 40 % zeolite content, cross-linked with fumaric acid (SPMMM-Fu), exhibited the densest and most continuous membrane structure, the lowest swelling degree and the best xylene compatibility. Pervaporation experiments demonstrated that the SPMMM-Fu exhibited superior xylene isomers selective separation performance compared to the templated-silicalite-1/α-Al 2 O 3 membrane. For the SPMMM-Fu, the maximum separation factor was achieved in binary xylene isomer solutions containing 10 % p-X. The total permeate fluxes in the aforementioned binary p-X/o-X and p-X/m-X isomer solutions were about 43.20 g m −2  h −1 and 34.66 g m −2  h −1 , respectively. The corresponding separation factors of p-X/o-X and p-X/m-X were about 34.65 and 39.73, respectively. The third-stage separation experiment demonstrated that the SPMMM-Fu could produce p-X with a purity ≥99.7 % from binary p-X/o-X isomer solutions. Long-term and variable-temperature pervaporation experiments suggested the SPMMM-Fu had excellent structural stability. Furthermore, reproducibility tests conducted on multiple batches of the SPMMM indicated that the SPMMM-Fu could be produced stably. The scalable experiment demonstrated that our strategy could produce large-area SPMMM-Fu (25 × 40 cm 2 ), exhibiting separation performance similar to that of small membrane coupons. This work presented a potentially low-cost and scalable approach for producing highly dense SPMMM with exceptional xylene compatibility, enabling efficient pervaporation separation of xylene isomers from their mixtures.