Solid Phase Synthesis Of Glyphosate Potassium

Glyphosate is a kind of broad spectrum herbicides.The potassium glyphosate salt has a greater market competitiveness in the glyphosate industry through the character of its quick effect,more resistant to rain erosion,can be effectively absorbed of the potassium ions entering into the soil or spraying on the leaves,which achieving the same result with considerable amount of potash fertilizer.Most of the existing methods of synthesizing potassium glyphosate salt need to be dried,crushed to get powdered potassium glyphosate salt.Increasing the cost,and having a higher requirements for equipment,as well as consuming higher energy.Using the kneading machine with a heating device,to synthesis the potassium glyphosate salt by drying method,the material is still solid,which simplifying the synthesis step and reducing the cost.However,the factors affecting the synthesis of glyphosate by drying method were not investigated.Therefore,it is necessary to determine and the influence of related factors on the synthesis of glyphosate potassium salt,and its reaction mechanism and establishing a dynamic model.The potassium glyphosate was synthesized by solid potassium carbonate and solid glyphosate in a stirred reactor of 500 ml.The amount of carbon dioxide produced by the reaction was examined by gas chromatography and analyzing the effects of gas humidity,reaction temperature,material ratio,velocity of N2,particle size and shaft speed on the reaction.The results showed that the moisture content of solid phase significantly affected the mass transfer between reactants.The reaction has three period:induction period,acceleration period and deceleration period.With the increases of the inlet gas humidity,the water content of solid phase reactant was increased,the reaction induction period was shorten,the reaction was easier to carry out,and the reaction conversion and the average reaction rate were increased in the same reaction time.When the gas humidity of ventilation is too high,the ability to take away moisture is decreased,the water resulting from the acceleration stage of the reaction will result in the aggregation of the product,and affecting the subsequent reaction.Under the same condition of introducing gas,with the increase of reaction temperature,the average reaction rate increased first and then decreased.There was an appropriate reaction temperature.An excessively high temperature will speed up moisture loss of the reaction system,reducing the water content in solid material and resulting decreasing reaction rate.With the decreasing of molar ratio of glyphosate and potassium carbonate,the contact probability between glyphosate with the same quality and potassium carbonate of glyphosate is increased,so the reaction of glyphosate can be accelerated.The smaller the particle size of glyphosate,the greater of the specific surface area,the more conducive to react.Too small particle size causes the more easily material bonding and the decreased reaction rate.There is a suitable particle size.The faster of the stirring speed,the faster updating surface of the material,the more conducive to continuously form the molten layer,thereby speeding up the reaction.The higher of the speed,the faster of the reaction rate.But restricting by the experimental device,the material is easy to be taken out of the reactor by the gas when the speed is too large,which is not conducive to the progress of the reaction.Solid-phase synthesis glyphosate potassium salt reaction is controlled by initial diffusion,kinetic model is:1—2/3 ?-?1-??2/3 = k1t:The reaction is controlled by nuclei after stepping into accelerated phase.kinetic model is[-ln?1-??]ⁿ =k₂t?n=2/3?.