SiO₂ Dopping γ-Alumina Supported Nickel Catalysts For Hydrogenation Of Nitroarenes

Aromatic amines have been widely used in medicine,rubbers,plastics and pesticides.Since 1980s,with the growing demand for diphenylmethane-4,4’-diisocyanate（MDI）in the plastics industry,the industrial process of aromatic amines has become even more important.Up to now,more than 80%aromatic amines are prepared by corresponding nitroarenes hydrogenation.The hydrogenation of nitroarenes has experienced the catalysts system of the metal/acid,alloy catalysts,supported metal catalysts in the last 200 years.Nevertheless,the milder reaction conditions and the better selectivity are always the goals pursued by researchers.Heterogeneous catalysts have been widely used in the industrial manufacture process.In nanocatalysis,the supports are not only used for the dispersion and adsorption of active metal species,but also provide the catalytic environment for the reactions.Such metal-support interaction has been received much attention in recent years and became an effective tool to enhance catalytic performance.For the thermal stability,the metal oxide supports are more applicably used in high-temperature industrial manufacture process.Alumina is a traditional metal oxide support.The usefulness in the catalytic process of alumina can be traced to the favorable combination of the high surface area,pore volume,pore size distribution and acidic sites.Modifying is an effective way to adjust the characteristics and expand the application range for alumina.In the industrial process,the silicon modified alumina has been wildly used in CO oxidation,desulphurization and denitrification to improve the thermal stability.In this thesis,a series of cheap and earth-abundant metal catalysts were prepared using silica modified alumina and used for nitroarenes hydrogenation under very mild conditions（25-35 ^oC,1-5 bar H₂）.By hydrogenation of nitrobenzene under gas-solid reaction,nickel catalysts industrial potential was investigated(TOF=365 h^-1,TON=975).The derivatization of aromatic amine was also studied.A series of characterizations were carried out to investigate the silicon oxide effect.Thus,this thesis is beneficial to further understand and expand the application of the silicon modified alumina and this thesis content including organic chemistry,heterogeneous catalysis,chemical engineering subjects,which has application and commercial prospect.