Functional defect-patching of a zeolite membrane for the dehydration of acetic acid by pervaporation

Pervaporation (PV) using zeolite membrane is one of the emerging technologies undergoing a rapid growth in recent years, regarded as an alternative method to distillation for its energy-efficient. However, grain boundary defects, especially for hydrophilic zeolite membranes, inevitably formed due to their polycrystalline structures and strong negative surface charges of Al-containing zeolites during hydrothermal synthesis, degrade their selectivity by providing nonselective transport pathway for permeating species. We show that functional defect-patching (FDP) can improve the PV performances of thin columnar membrane of a certain zeolite (mordenite) by eliminating grain boundary defects, by grafting functional polymer groups onto grain boundaries. This methodology enables the preparation of mordenite zeolite membrane (MZM) with high PV performances for the dehydration of acetic acid (AcOH) and holds promise for realizing high-throughput and scalable production of the membrane with improved energy efficiency. Furthermore, durable tests for acid stability showed that the FDP-treated membrane displayed a reasonably strong acid resistance. Finally, the products fabricated were characterized by a variety of techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), diffuse reflectance FT-IR spectroscopy (DRIFTS) and thermogravimetric analysis (TGA).

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (299 K)Download as PowerPoint slideResearch highlights▶ FDP is an effective means for elimination of the grain boundary defects. ▶ FDP markedly improves the PV performances of the MZM. ▶ The membrane P4VP-2 is moderately more productive than the membrane PVI-2. ▶ Acid stability of the FDP-treated membrane by P4VP groups improves greatly. ▶ The functional groups effectively prevented dealumination from zeolitic surface.