Catalytic membrane micro-reactor with nano Cu/ZIF-8 assembly in membrane pores by flowing synthesis combining partial ion-exchange

Abstract

A catalytic membrane micro-reactor (CMMR) is fabricated, with nano Cu/ZIF-8 particles immobilized in the pores of the microfiltration membrane for flow-through catalysis. Nano ZIF-8 is firstly assembled in polyethersulfone (PES) membrane pores by flowing synthesis and then Cu nanoparticles (NPs) are synthesized in-situ in ZIF-8 by the partial ion-exchange reaction. Cu/ZIF-8 nanoparticles are distributed evenly throughout the whole direction of membrane thickness while Cu NPs are dispersed well in ZIF-8. The 4-nitrophenol (4-NP) reduction is used to test the performance of the CMMR. The 4-NP reduction rate being 99.3% is achieved when the membrane flux is 2293 L m −2 h −1 . The CMMR has good stability for over 210 min and presents a surprisingly high apparent reaction rate constant ( K app , 837.43 min −1 ) at room temperature with the loading of ZIF-8 being 85 mg g −1 (PES) and Cu loading cycle number being 1. Compared with batch catalysis by powder catalysts, the K app is increased by 4 orders of magnitude via flow-through catalysis mode using CMMR. The nanoscale configuration of ZIF-8 and Cu NPs assembled inside pores of the membrane enhances remarkably the catalytic activity owing to the enhanced contact and mass transfer in the confined space of membrane pores. A catalytic membrane micro-reactor (CMMR) with nano Cu/ZIF-8 immobilizing in membrane pores was fabricated by flowing synthesis combining partial ion-exchange. This structure provides excellent activities due to the synergistic effect of membrane pores, ZIF-8, and nano Cu. Cu/ZIF-8 catalytic membrane micro-reactor fabricated by flowing synthesis method Cu/ZIF-8 assembled throughout membrane thickness with high loading and dispersity Synergistic effect between membrane pores, ZIF-8 and nano Cu enhances 4-NP reduction Reduction rate of 4-NP over 99.3% achieved with stability over 210 min Apparent reaction rate constant improved by 4 orders of magnitude via flow-through catalysis