Abstract
A new approach to the synthesis of mixed-type immobilized catalysts by frontal polymerization of metal-containing monomer in the presence of highly dispersed mineral support has been developed. Synthesis of the acrylamide Pd(II) nitrate complex, Pd(CH2=CHCONH2)2 (NO3)2 (PdAAm), on the SiO2 (Al2O3, C) surface and its consequent frontal polymerization and reduction lead to the formation of organic-inorganic composites with polymer-stabilized Pd nanoparticles. The immobilized metal complexes and palladium nanoparticles were characterized by various physical and chemical methods. The synthesized hybrid nanocomposites are efficient and selective catalysts for hydrogenation of cyclohexene, alkene, and acetylene alcohols, as well as di- and trinitrotoluene. Catalyst intermediates separated by nondestructive testing method have been described and changing in the palladium charge during the catalytic process has been identified.
Highlights
In recent years materials containing metal nanoparticles were intensively studied specially as catalysts due to their unique physical and chemical properties [1], high ratio of surface atoms to the total number of atoms in a particle, and possibility to vary catalytic properties by controlling the size of particles [2,3,4]
PdAAm metal monomer was synthesized by a modi ed method for preparation of acrylamide complexes of transition metal nitrates [19]
Acrylamide complex of Pd(II) nitrate was synthesized by substitution of crystallization water in crystalline hydrate of metal nitrate by acrylamide molecules (AAm)
Summary
In recent years materials containing metal nanoparticles were intensively studied specially as catalysts due to their unique physical and chemical properties [1], high ratio of surface atoms to the total number of atoms in a particle, and possibility to vary catalytic properties by controlling the size of particles [2,3,4]. E aim of this paper is to demonstrate a new approach to the design of catalysts by the frontal polymerization of acrylamide Pd(II) nitrate complex on inorganic supports and to characterize the features of their catalytic properties in reactions of hydrogenation of various unsaturated compounds (cyclohexene, ole nic and acetylenic alcohols and selective reduction of di-and trinitrotoluene). F 2: XPS spectra of (a) acrylamide complex monomer with Pd(NO3), (b) PdAAm a er polymerization, and (c) the same a er cyclohexene hydrogenation. T 2: Results of the XPS, XRD, and TEM analysis of polymer hybrid nanocomposites based on PdAAm. 3.6–4 4 8 obtained by the treatment of Na2PdCl4 complex salt (5.5 g, 1.84⋅10−2 mol.) with sodium hydroxide. PdAAm metal monomer was synthesized by a modi ed method for preparation of acrylamide complexes of transition metal nitrates [19]. F 3: Electron micrograph of poly-PdAAm/SiO2 (magni cation of 125000x)
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