Preparation Of Highly Dispersed Metal Nano-heterogeneous Catalysts And Theirapplications In Catalytic Transfer Hydrogenation Reaction

Aromatic amines are vital raw materials and intermediate for the manufacture of diverse chemicals such as pesticides,surfactant,pigment,dyes,polymer,and herbicides and so on.The most commonly employed method for the fabrication of aromatic anilines is the reduction of corresponding nitroarenes.However,the traditional reduction approach requires stoichiometric reducing agents?such as Zn,Fe,Sn and metal sulfides?that produce large amount of waste acids and residues,which result in serious environmental pollution problems.The catalytic transfer hydrogenation?CTH?of nitro compounds can be performed under mild conditions?e.g.atmospheric pressure,room temperature?,which has merits of high selectivity,less pollution to the environment,security and simple to operate.So an increasing number of researchers have shifted their attention to catalytic reduction.Hydrogenation of unsaturated carbon-carbon bonds?C=C?is an important reaction in the chemical industry,particularly in the synthesis of flavor,fragrance chemistry and pharmaceuticals.The CTH has been considered as a promising method for the hydrogenation of alkene,in which dangerous hydrogen is replaced by formic acid?FA?.The method is more environmentally friendly,economical,safe,and therefore is one of the hot research.Graphitized carbonitride?g-C₃N₄?has excellent wear resistance,thermal stability and chemical stability,can be used as a nitrogen source of metal nitride,electrochemical materials,catalysts,catalyst carriers,adsorbents and so on.MOF-C with the high stability and chemical stability,have been widely used as a catalyst carrier.Therefore,it has aroused the attention and research of many researchers.In this work,a variety of catalysts prepared and used in CTH nitro compounds and olefin compounds.This dissertation is mainly concerned with the following aspects:1.Bimetallic AgPd nanoparticles anchored on metal-organic framework?NH₂-UiO-66?derived N-doped porous carbon?NPC-UiO-66?was fabricated and used as the catalyst for the catalytic transfer hydrogenation of nitroarenes using FA-formate as hydrogen source.The results demonstrated that Ag₁Pd₉@NPC-UiO-66 composite exhibited extraordinary catalytic activity toward the hydrogenation of nitroarenes to anilines at room temperature.A series of substituted nitroarenes were successfully converted to the corresponding anilines in high yields under ambient conditions with other reducible groups remaining intact.2.Well-dispersed Pd nanoparticles were anchored on g-C₃N₄ nanosheets?g-C₃N₄ NS?,which were prepared by a liquid-phase exfoliation method.The hybrid material displayed excellent catalytic activity for the transfer hydrogenation of nitroarenes.The reactions can be conducted smoothly in water at room temperature with formic acid as hydrogen source.Aniline was produced in excellent yield?>99%,TOF:853?,surpassing majority reported heterogeneous catalysts using formic acid or formates as hydrogen source.The heterogeneous Mott-Schottky catalyst can be reused for five of cycles without any obvious loss of its catalytic activity.3.Porous g-C₃N₄ nanosheets/reduced graphene oxide?rGO?composite was synthesized via hydrothermal co-assembly of GO and g-C₃N₄ nanosheets.The g-C₃N₄NS/rGO supported Pd nanocatalyst displayed a remarkable catalytic activity for the hydrogenation of alkene with FA and formates as hydrogen source at 30 ^oC and atmospheric pressure.In addition,the catalyst also showed higher catalytic activity for the CTH of nitro compounds.The Pd-g-C₃N₄ NS/rGO₂₀0 exhibited an excellently high stability after five successive cycles without significant loss of its catalytic activity.