A New Catalyst And Technology For One- Step Of Benzene To Aniline

Aniline is an important fine chemical raw materials in chemical industry,which is widely used as an important intermediate or precursor in many areas. The current industrialized method for the production of aniline mainly adopts multi-step process. Although these processes are relatively mature, these methods have many shortcomings, such as the use of corrosive materials in the production process, the complicated process operation, low efficiency of raw materials usage, harsh reaction condition, long production cycle time, more by-products and the related environmental problems. Therefore, the synthesis of aniline has been a hot and difficult research topic in chemical industries at home and abroad. One step synthesis of aniline, for the direct amination of benzene, greatly improving the atoms utilization efficiency, is a very attractive and challenging method from the green chemistry and synthetic chemistry point of view. Thus, developing highly effective catalysts and finding suitable aminating agents are the key to solve the above problems. The hetero-atom substituted aluminophosphate sieves(MeAlPO4-5) have been a promising multi-functional catalysts because of their special channel structure, good adsorption and thermal stability, the acid sites and the redox active sites. In this paper, various NiAlPO4-5 molecular sieves were hydrothermally synthesized, their surface structure, morphology, pore structure and thermal stability were characterized. And we investigated their catalytic performance for benzene one-step ammoniation of aniline.The results show that the molecular sieves have the crystal structure and morphology of AlPO4-5; pore structure is uniform and stable, the pore size is located between 0.4~1.5 nm, which shows that the catalysts are with microporous structure. The effect of the nickel doping amount,reaction temperature, reaction time, the acidity of the reaction medium, the ratio of raw materials,catalyst input,recyclability of the catalyst on the catalytic performance for benzene ammoniation was investigated. The optimized amination conditions were as follow nNH2OH·HCL/nbenzene 1:1, 70 v.% acetic acid solution, temprature 353 K,time 4 h,under atmospheric pressure, Ni AlPO4-5(0.3) as the catalyst,with the highest aniline yield of 73.2% and 100% selectivity to aniline. And this catalyst can be used up to 5 cycles with little activity declining. This process has great potential in industrial exploration.