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

Abstract

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 p-nitrophenol (p-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 p-NP conversion rate being over 95% can be obtained under the condition of a membrane flux of 1.59 mL·cm–2·min–1. This Cu–Ag/PES CMMR has good stability and has a potential application in industry.

Catalytic Membrane Nanoreactor with Cu–Agx Bimetallic Nanoparticles Immobilized in Membrane Pores for Enhanced Catalytic Performance

“…The fabrication process of the catalytic membrane microreactor is based on the previous reports with several modifications . The general content is as follows: First, the Cu–MI/PES membrane was prepared by flowing synthesis, with the Cu­(NO 3 ) 2 solution (0.3 M, 50 mL) and the 2-MI aqueous solution (1.2 M, 50 mL) alternately flowing through the membrane, both for 30 min.…”

“…During the catalytic process by CMNR with Cu−Ag x immobilized in membrane pores, the contact between the catalyst and active H can be enhanced since the reaction interface provided by the catalyst surface can be effectively exposed, owing to the good dispersibility of the membrane pores, as described in our previous studies. 8,9,38,40 After the process of the mixture (p-NP + DMPO + NaBH 4 ) flowing through the CMNR, the nine-line SPR spectrum still exists with a slightly higher signal intensity, indicating that the presence of bimetallic catalysts is beneficial to generate H• radical species from NaBH 4 . At the same time, the conversion rate of p-NP is lower than that in the case without DMPO, suggesting that there exists a competitive reaction between p-NP and DMPO, namely, hydrogen radicals used for p-NP hydrogenation are trapped by DMPO.…”

“…In addition, the mechanism, possible pathways, and catalytic efficiency were also studied. 38 The general content is as follows: First, the Cu−MI/PES membrane was prepared by flowing synthesis, with the Cu(NO 3 ) 2 solution (0.3 M, 50 mL) and the 2-MI aqueous solution (1.2 M, 50 mL) alternately flowing through the membrane, both for 30 min. Second, the solid precursor (Cu−MI) immobilized in membrane pores was reduced in situ to Cu nanoparticles under the condition of a continuous flow of a reducing agent (NaBH 4 ) through the membrane.…”

“…In our previous study, the flowing synthesis method has been developed to in situ immobilize the core–shell nanostructural catalysts in membrane pores. ,, For the Cu–Ag bimetallic core–shell catalysts immobilization, the solid precursor prepared by Cu 2+ and 2-methylimidazole (2-MI) was first deposited in the membrane pores. After that, Cu nanoparticles were prepared after flowing the reducing solution through the membrane.…”

A Flow-through Electrode for Superior Water Splitting by Mitigating Bubble Induced Overpotential

“…First, CoB nanocatalysts were assembled on Ni foam after the flowing synthesis process. 29,30 In brief, cobalt salt aqueous (0.5 M) and NaBH…”