Preparation of poly (vinyl alcohol)/palygorskite-poly (ionic liquids) hybrid catalytic membranes to facilitate esterification

Poly (vinyl alcohol) (PVA) hybrid catalytic membranes were prepared for esterification via blending PVA with solid catalyst (PAL-PILs), which was synthesized by grafting polymerization of acid ionic liquids (PILs) (1-butysulfonate-3-vinylimidazole hydrogen sulfate) onto natural nanofiber-like palygorskite (PAL). The embedding of PAL-PILs can enhance the thermal stability, mechanical strength and hydrophilicity of membranes. The cross-linked poly (vinyl alcohol) (CPVA) hybrid catalytic membranes (CPVA/PAL-PILs) was preferable to water removal under mild conditions. Moreover, the hybrid membrane exhibited an obvious catalytic performance for the esterification of oleic with methanol under mild reaction conditions. When running in a cross-flow catalytic membrane reactor (CMR), the yield values reached about 8.7%. Importantly, the yield can be improved by increasing packing density of CPVA/PAL-PILs membranes. Meanwhile, the CMR technology does not require separation of catalysts. The results offer a great potentiality for these catalytic membranes in the CMR for further research.