Gold nanoparticles supported onto amine-functionalized in-capillary monoliths meant for flow-through catalysis: A comparative study

[摘要] Monoliths functionalized with ethylene diamine-derived ligands were synthetized within micro-sized channels as highly permeable catalytic supports for the immobilization of in-situ generated gold nanoparticles. The as-obtained hybrids, essentially differing on the grafted amine-containing ligands were compared, notably regarding the immobilized nanoparticles morphology and their dispersion at the monolith pore surface. Further, such in-capillary hybrid monoliths were successfully applied as flow-through microreactors for the catalytic reduction of nitroaromatic compounds. The general synthetic route for preparing these composite materials consisted in a three-step procedure involving (i) UV-induced polymerization of N-acryloxysuccinimide and ethylene glycol dimethacrylate in toluene, (ii) surface grafting of a series of ethylene diamine derivatives through nucleophilic substitution of N-hydroxysuccinimide leaving groups, and (iii) successive in situ reduction of tet-rachloroauric acid to generate monolith-adsorbed gold nanoparticles. The successful synthesis of such hybrid monoliths was ascertained by in-situ Raman spectroscopy, EDX analysis and SEM observations. Microscopy demonstrated the key role of the grafted amine-bearing ligand regarding the morphology, size and surface coverage of the immobilized gold nanoparticles at the monolith pore surface. Monolith-adsorbed gold nano-particles exhibited good catalytic activities towards the conversion of nitroaromatic compounds into the cor-responding amino derivatives in a flow-through process. This study clearly demonstrates the key role of the nature, primary vs. secondary, of the chelating amine in the morphology (shape, size, dispersion) of the sup -ported gold nanoparticles.

[发布日期] 2021-09-16

[关键词] Gold nanoparticles;Catalytic reduction;Monolith;Amino-functionalization;Polymer-supported nano-metal