Ultrafiltration Pd-immobilized catalytic membrane microreactors continuously reduce nitrophenol: A study of catalytic activity and simultaneous separation

•Catalytic membranes assembled by immobilizing Pd nanocatalysts via immersion precipitation.•The high spatial distribution of Pd nanocatalysts enables high utilization of catalytic sites.•Catalytic nanoparticles act as hydride carriers transferring H* from sodium borohydride to 4-NP.•Pd nanocatalysts show low leaching within CMMRs due strong chemical interaction with polydopamine.•CMMRs combine UF separation (>90% rejection of 1 MDa PEO) with catalysis (>99% conversion of 4-NP).