Development Of Continuous Process For The Production Of O,S-dimethylphosphoramidothioate Based On Waste Minimization

There is currently a great deal of interest in the development of methods that can be used to prevent or at least minimize the generation of pollution w-ith the people caring about the environment and energy. It has been the neces-sary option for the sustainable development of factory. Batch chemical process is the usual process in producing fine chemical product.It is simple, convenientand small investment in producing many products.But its production capacity issmall, labouring extent is great and it depends on worker's experience. So the quality and the yield of product is unstable and there is always much waste todeal with.In contrast,the benefits of continuous process include: More efficient utilization of energy and raw materials. Recovery of heats of reaction.High-int-ensity mixing, enhancing process selectivity, minimised risk of runaway reaction,smaller plant, cheaper plant,process automation.The enviroment impact assessme-nt(EIA):efficiency of raw material (BA) and the ratio of product mass to unde-sirable material mass (MB) was proposed to be used to analyse the minimizati-on of waste in the continuous producing O,S-dialkyl phosphoroamidothioate and its intermediate O-miethyl dichlorothiophosphate, O,O-dimethyl phosphorochori-dothioate,O,O-dimethyl phosphoroamidothioate. It has important signifycance th-eoretically and practical application to develop continuous producing process to replace traditional batch chemical process when the production capacity is enl-arged. It can rise the quality and yield of product, decrease the rate of equip-ment size to production capacity, decrease energy consumption, bring about cle-aner production.The model of continuous producing O-miethyl dichlorothiophosphate reactor was based on the kinetics of synthesizing O-miethyl dichlorothiophosphate which was proposed by previous literature.The retention time of recycle tubular reactor is shorter and the temperature of reaction is lower, the quality and the yield of product is rised.The mole ratio of thiophosphoryl chloride to methanol is decreased ,the waste of the process is reduced.12000 ton/y of recycle reactor series connection tubular reactor was built in a factory.It indicates that the quality and the yield of product is rised about 1.5% and the production capacity of one set equipment is 5 times compared with one set batch reactor.The reaction kinetics of O,O-dimethylphosphorochloridothioate synthesis wasstudied.Multistage recycle tubular reactors in series was founded to produce O,O-dimethyl phosphorochloridothioate continuously. The amount of alkali was optimized on the objective of the total yield of O,O-dimethylphosphorochlorido-thioate with complex methods optimization by MATLAB.When the stage of ser-ies is increased, the ratio of recycle is reduced, the reaction temperature is do-wn,the quality and the yield of product is rised. The quality can reach 94.35%and the yield can reach above 93.86% in optimal conditions when six stages recycle tubular reactors in series. The pilot-scale experimental result of one re-cycle tubular reactor agrees well with the calculation value by model. It provi-des guide for designing and optimizing the equipment in industrial producing process.The ammonolysis reaction kinetics of O,O-dimethylphosphorochloridothioate without catalyst was studied. The model showes that the effects of the initial mole ratio between ammonia and acyl chloride, concentration of ammonia and temperature on the reaction rate are very obvious. In addition, the effect of concentration of acyl chloride on the rate of ammonolysis is very small.The reaction rate demonstrates the pseudo-first order to ammonia during early period of reaction and the second order to ammonia and acyl halide during the late period. A new green process is proposed to produce O,O-dialkyl phosphoroamidothioate continuously by recycle tubular reactor with the analysis of waste minimization and the study of reaction kinetics. 25kt/y of recycle tubular reactor was built .It is indicated that the quality and the yield of product is rised 0.74% and 2.93% individually. The production capacity of one set equipment is 7 times compared with batch reactor.It can decrease a great deal of energy consumption.The isomerization reaction kinetic of O,O-dialkyl phosphoroamidothioate was studied by simplex optimization.The rate of isomerization behaves the firstorder to dimethyl sulphate and O,O-dialkyl phosphoroamidothioate individually.A model of CSTR seried tubular reactor was founded to produce O,S-dimethyl phosphorochloridothioate continuously. It is indicated that the yield of product is rised 1.2%～1.7% in optimal conditions contrast to batch process.A questionof mult-objective optimization was built about reaction-separtion-recycle system.It was optimized to maximize the total yield and the ratio of product mass towaste mass. The mult-objective optimization was converted to simple objective optimization by linear synthesis.The lower distillation pressure can increase the total yield and the ratio of product mass to undesirable material mass. When the quality of O,O-dialkyl phosphoroamidothioate is rised, the ratio of product mass to undesirable material mass can be increased obviously. It indicates that the quality can reach above 85% and the total yield of O,S-dialkyl phosphoro-amidothioate can reach 96%. The green integration flowsheet of isomerization-molecular distillation-recycle is proposed. It has good application foreground in industrial process.