Study On The Catalytic Synthesis Of Methyl Phosphonic Dichloride That The Intermediate Of Glufosinate-ammonium

Methyl phosphonic dichloride is the principal starting material for the synthesis of organophosphorus compounds and the important intermediate of herbicide glufosinate-ammonium, which has a wide use. The synthetic methods of methyl phosphonic dichloride are mainly including liquid-phase method, gas-phase method. The condition of Liquid-phase method is mild and easy to operate, but the synthesis route is too long, the expense of raw material is high, and result in heavy environmental pollution. The process of gas-phase method is simpler, less side reaction, fewer wastes. But the reaction takes place under high temperature (600℃), the operation is quite difficult, higher risks, and the rate of single conversion is low. At present, production and sales of methyl phosphonic dichloride was monopoly by Bayer company in germany. , In recent years, though extensive study is conducted in china, the technology is still not perfect. Therefore, if the industrial production of methyl phosphonic dichloride is possible, it has both wide market and foreground.In this thesis, study on catalytic synthesis of methyl phosphonic dichloride, with various perovskite-type catalysts, supported metal clusters and hexaaluminate catalyst LaMnAl₁₁O_19-α as catalyst. Catalytic activity of various catalysts in the catalytic synthesis of methyl phosphonic dichloride was investigated in detail. Effect of catalytic activity to conversion ratio at different condition was studied (different particle size of catalyst, reactant ratio, reaction temperature), then, the proper reaction condition of each catalyst was decided, we test stability, high temperature resistance, corrosion resistance under these conditions. The catalytic synthesis of methyl phosphonic dichloride using above catalysts have been not reported.The main production and conclusions of the dissertation are listed as follows:1. The catalytic activity over fourteen catalysts that used in atalytic synthesis of methyl phosphonic dichloride was studied. The effects of reactant molar ratio, catalyst mesh and reaction temperature on catalytic activity were studied, the suitable reaction condition of each catalyst was determined. It was also to study the service life of catalyst by repetitive experiment.2. The series catalysts of potassium cobalt lanthanum of perovskite-type have higher activity to the reaction. La_0.7K_0.3CoO₃ has the best reaction activity,and has good high temperature resistance, corrosion resistance.In the reaction, the suitable reaction condition of La_0.7K_0.3CoO₃ of potassium cobalt lanthanum as follows: the reactant ratio CH₄:PCl₃=5:1, catalyst diameter (20⁴0 mesh), reaction temperature,300℃. The highest conversion rate is 9.59%. The series catalysts of perovskite-type have low cost, good high temperature resistance and corrosion resistance, also have higher activity, therefore, the series catalysts of perovskite-type is the first choice for the reaction.3. Because of the higher request of the reaction conditions, catalysts should has good high temperature resistance and corrosion resistance, makes some theoretically good catalysts fails to showed higher activity, Such as supported catalyst, showed little activity. The hexaaluminate catalyst LaMnAl₁₁O_19-α has low activity, the highest conversion rate is only 6.84% (300℃), also has poor stability and short service life.4. The results showed that, reaction condition has more improved when the catalyst is used: in the experiment, need not aerating oxygen as cocatalyst, solving the problem of easy to explode, enhances the safety, meanwhile to avoid the formation of by-product such as phosphorus oxychloride; the energy consumption is reduced by lowering the temperature, and saving experiment cost.