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. 1. Introduction 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 [2–4]. Zero-valent palladium complexes and nanoparticles are well known as efficient and selective catalysts for many organic reactions such as alkene arylation [5, 6], cross-coupling [7], hydrogenation of dienes, olefins [8, 9], and unsaturated alcohols [10]. Liquid phase catalytic hydrogenation of aromatic nitro compounds is widely used to produce corresponding amino derivatives, which are intermediates in the production of plastics, pharmaceuticals, and so forth. Hydrogenation of trinitrotoluene (TNT) in recent years becomes a reaction of practical importance for utilization of nitroaromatic explosives to useful chemicals (dyes, amino compounds, etc.) [11, 12]. Platinum metals catalyze selective reduction of nitroaromatic compounds. Particular attention is paid to developing effective and selective palladium catalysts based on complexes and nanoparticles [13–16]. Aggregation and agglomeration of nanoparticles limits their use as catalysts, so they are fixed on supports (metal oxides, zeolites, carbon, etc.) or stabilized with different types of ligands, including polymers. One of the promising methods to obtain metal polymers is a polymer-mediated synthesis based on in situ poly- and copolymerization of metal-containing monomers with subsequent controlled thermolysis of the resulting products. This approach
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