Metal Materials: Synthesis And Applications In Catalysis

The chemical industry is one of the pillar industries in the contemporary industrial development, and the development of the chemical industry is inseparable from the catalyst. Selecting suitable catalysts in different chemical reactions can accelerate the reaction, reduce corresponsive costs, improve product quality and get the product that can not be produced by general synthesis method, in order to achieve diversification of energy sources, reduce energy consumption and improve utilization. The use of the catalyst plays an invaluable role in development of the industrial economic efficiency. Like our country where the energy is the relative shortage, it is of great practical significance and strategic significance.From the historic organic metal complex catalyst, simple and reactive small organic molecules catalyst, to the newly developed nano-catalysts, we hope the catalysts to be efficient, gentle, green and low corrosive. Both of organic metal complex catalyst and organic small molecule catalyst have high activity and selectivity, mild reaction conditions and other characteristics. And due to the special nature of nanomaterials, the emerging nano-catalysts are more efficient and active. However, there are some disadvantages of these catalysts. For example, most of the organic metal complex catalysts are sensitive to water and air. The structure is more complex and the catalyst synthesis steps are complicated; Most of organocatalysts have so poor thermal stability that they can not be used in some high-temperature reactions, which restricts its applicability. In addition, these two types of catalysts are difficult to separate, recover and regenerate. While the nano-catalysts make up this deficiency, because of the conveniency to separate, recover and recycle. However, because of the large specific surface area and high surface energy, metal nano-catalysts are very easy to gather together; Due to small size of metal nano-catalysts particles and high surface atomic coordinatively unsaturation, they are prone to the oxidation reaction with oxygen in the air. Therefore, this paper studied the catalytic synthesis from organic molecular materials and nanomaterials in order to promote the settlement of these problems existing in all types of catalyst.In this paper, according to selecting the suitable small molecules catalyst, designing the new nanocomposite structure catalyst and screening reaction conditions for the catalyst, various catalytic organic reaction systems achieve high activity and selectivity. As an effective complement of catalytic organic synthesis system, they adequately address the environmental pollution and other problems of the conventional organic synthesis applications generated in the process and achieve a highly efficient and green catalyst for promoting applications of the catalyst and catalytic reactions in organic synthesis chemistry and chemical industry production. The main contents are as follows:(1) Synthesis of aromatic azo compounds: Bis(2,4-pentanedionato-o,o’) palladium(II) was selected as a catalyst from a variety of noble metal salts and applied to the synthesis of aromatic azo compounds efficiently by reductive coupling reaction of nitrobenzene; Under mild reaction conditions, the catalytic properties of palladium catalyst were studied in the "green" reaction conditions by choosing two different hydrogen donors, hydrogen and isopropyl alcohol. In addition, from the economic point of view, we attempted to use ordinary metallic copper catalyst instead of a noble metal catalyst for the synthesis of an azo compound to obtain the target product by oxidative coupling reaction of aniline. The catalyst’s structures were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM), atomic absorption(AAS) and other techniques, combined with gas chromatography(GC), nuclear magnetic resonance(NMR), mass spectrometry(MS) and other tests on the catalytic organic products. On basis of that, the appropriate reaction mechanism was proposed to explain the corresponsive phenomenon. Thus multiple green catalytic reaction systems were successfully built.(2) Benzylamine oxidation: As a supplement of ordinary metal copper catalyzed reaction system, the oxidation of benzylamine was attempted by regulating the ligand types. Under mild reaction conditions, different ligands were added to the reaction could make benzylamine generate benzonitrile or dibenzyl imine with high selectivity, in which copper catalyst with high catalytic activity in the "green" reaction conditions was further investigated. Also, by scanning electron microscopy(SEM), gas chromatography(GC), nuclear magnetic resonance(NMR), mass spectrometry(MS) and other tests on the reaction, suitable reaction mechanism was proposed to explain the corresponsive phenomenon. Thus a benzylamine oxidation green catalytic system was successfully built.(3) Synthesis and catalytic properties’ study of nanomaterials: By design and chemical reduction, the uniform composite nano-materials were successfully synthesized. The novel materials were characterized by the transmission/high-resolution transmission electron microscopy(TEM/HRTEM), high-angle annular dark field(HAADF), surface mapping, line scanning, photoelectron spectroscopy(XPS), X-ray diffraction(XRD) and other tests. Its surface morphology which is closely related to catalytic performance parameters and valence and so on was studied. With the composite nanomaterials as catalyst, we studied the reduction of nitrobenzene under mild reaction conditions, the catalytic properties and recycling properties of nano-catalyst as well. A green nano-catalytic reaction system was successfully built.These catalytic materials have higher catalytic activity and selectivity than the conventional catalysts, and the reaction conditions are mild and green. The scope of substrates is also very broad. So it is potential for widely applications in industrial production.