One-step Synthesis Of M-Tolunitrile By Heterogeneously Catalysed Liquid Phase Ammoxidation

Aromatic nitriles are valuable intermediates and reactants in the fine chemical sector used for the systhesis of several Pharmaceuticals, dyestuffs and pesticides, However, their synthesis can be problematic, hazardous or environmentally damaging. For example: the yield of m-tolunitrile are sometimes high with traditional synthesis methods but a number of hazardous reagents, expensive feed components and solvents are used. Another process for the preparation of m-tolunitrile in a single step reaction is the vapour phase ammoxidation, which is ecologically and economically profitable route, but the selectivity for m-tolunitrile is very low' '.therefore, in terms of simplicity, safety and waste-minimization, the development of new and practical methodologies on the production of m-tolunitrile is welcome.Firstly, it is the target reaction that prepare m-tolunitrile by liquid phase ammoxidation of m-xylene. The reaction device, the control system and the analysis system of the materials were developed, and the spectrum of FR-IR and H¹NMR of m-tolunitrile were provided.Secondly, the difference of homogeneous catalysis and heterogeneous catalysis were studied. The results are follows: (1) the catalysts such as the salts of cobalt and manganese, which is often used in the liquid phase reaction, can also be applied to liquid phase ammxidation. (2)different kind of the third components has different influences to the catalysts' activity. being the third components, nickel is a preferable accelerator. The silica supported Co-Mn-Ni oxide catalyst can increase the conversion of m-tolunitrile, while the selectivity is still preterable. The catalyst contained of cobalt, manganese and nickel was selected.Thirdly, the catalysts were characterized by means of FI-IR, SEM and SAA, the results showed that: (1) the activity of the catalyst is associated with their specific surface area and pore volume.(2) the species of the active component is (Co, Mn)(Co, Mn)₂O₄. (3) the chemical bonds of supporter were influenced by active components. (4) sinter is perhaps the prime reason to decrease activity.Finally, the reaction mechanism of liquid phase ammoxidation was discussed.