Simultaneously catalytic oxidation of benzyl alcohol to benzaldehyde and selectively phase separation via a sandwich-like polymeric PVDF membrane

Abstract

It is of significance to improve the interfacial catalytic performance of noble metal nanocatalysts in heterogeneous reactions and to achieve real-time oil-water phase separation to reduce the separation and purification process. In the current work, a sandwich-like polymeric membrane was prepared, with a core layer of poly(vinylidene fluoride) (PVDF)/poly(methacrylic acid) (PMAA) microspheres/Pd nanoparticles as the reaction center, and a hydrophilic semi-interpenetrating polymer network (semi-IPN) as well as a hydrophobic PVDF as shells for the benzaldehyde green preparation. The process proceeded by using the sandwich-like membrane to catalyze the interface reaction between the organic phase of benzyl alcohol and the aqueous phase of H2O2 and the effect factors such as reaction temperature, feed flow rate, the initial benzyl alcohol concentration and catalyst dosage were investigated to get the optimal oxidation conversion and selectivity. Results indicated that the interface reaction went well, without the aggregation and leaching of Pd nanoparticles from membrane support. Furthermore, the product benzaldehyde could be selectively transported to the organic phase. The sandwich-like catalytic composite membrane integrates the catalysis with phase separation, providing a new strategy for the preparation of the chloride-free benzaldehyde. What's more, the sandwich-like catalytic membrane acts as an ideal option for a large-scale catalysis application with integrated advantages of high activity, convenient operation and omitted separation of catalysts and products from heterogeneous catalytic interfacial reaction system.