Cu-Ag Bimetallic Core-shell Nanoparticles in Pores of a Membrane Microreactor for Enhanced Synergistic Catalysis.

A bimetallic catalytic membrane microreactor (CMMR) with bimetallic nanoparticles in membrane pores has been fabricated via flowing synthesis. The bimetallic nanoparticle is successfully immobilized in membrane pores along its thickness direction. Enhanced synergistic catalysis can be expected in this CMMR. As a concept-of-proof, Cu-Ag core-shell nanoparticles have been fabricated and immobilized in membrane pores for -nitrophenol (-NP) hydrogenation. Transmission electron microscopy (TEM) for the characterization of the bimetallic core-shell nanostructure and X-ray photoelectron spectroscopy (XPS) for the characterization of the electron transfer behavior between Cu-Ag bimetal have been performed. The Ag shell on the core of Cu can improve the utilization of Ag atoms, and electron transfer between bimetallic components can promote the formation of high electron density active sites as well as active hydrogen with strong reducing properties on the Ag surface. The dispersed membrane pore can prevent nanoparticle aggregation, and the contact between the reaction fluid and catalyst is enhanced. The enhanced mass transfer can be achieved by the plug-flow mode during the process of hydrogenation catalysis. The -NP conversion rate being over 95% can be obtained under the condition of a membrane flux of 1.59 mL·cm·min. This Cu-Ag/PES CMMR has good stability and has a potential application in industry.