Porous PVA-g-SPA/PVA-SA Catalytic Composite Membrane via Lyophilization for Esterification Enhancement

A catalytic composite membrane was developed for the enhancement of esterification by lyophilization for the first time. The catalytic composite membrane was composed of a poly(vinyl alcohol) (PVA)-sodium alginate (SA) separation layer and a spongy porous catalytic layer cross-linked by PVA and 4-sulfophthalic acid (SPA). Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) results indicated the successful synthesis of the catalytic composite membrane. The membrane properties were evaluated by ethanol dehydration and esterification. The conversion rate of acetic acid reached 95.9% after 12 h. Compared with batch reactions, the conversion rate increased by 24.4%. After five cycles, the membrane still maintained outstanding catalytic activity. The resistance of mass transfer was analyzed, and the results showed that the porous structure reduced the catalytic layer resistance to total resistance from 70.27 to 32.88%. The composite membrane with a spongy porous catalytic layer exhibited superior dehydration and catalytic performance.