Study On The Synthesis Technology And Application Of Cyanuric Acid

Cyanuric acid is an important fine chemical intermediate that is made from urea.And it is the urea downstream product whose production is encouraged by the Chinese government.The production technology of cyanuric acid mainly includes direct pyrolysis,molten salt method and solvent method.The purity of crude product was about 50% for direct pyrolysis method,and the finished product must be refined by acid cooking.For this kind of technology,energy consumption is high,production period is long and environmental pollution is more serious.The research on molten salt method was less,as well as the yield and purity of product increase with respect to direct pyrolysis method.The advantages of solvent are the purity of product over 96%,process without acid cooking,low energy consumption,continuous production,and easy to pollution control.But the color of product is dark for this technology,which has been limiting its industrial promotion.In view of the above situation,three kinds of synthesis methods were investigated from the perspective of industrial clean production in this paper.Through a large number of solvent selection and process optimization,the product with excellent color was prepared,and the production process was clean and friendly for environment.At the same time,the synthesis and application of rare earth cyanurate heat stabilizers were studied.For direct pyrolysis method,ammonium chloride presents remarkable catalyst effect than other catalysts,which increases the yield of product by 19% relative to no catalyst.The suitable process conditions are as follows,the catalyst composition m(NH4Cl): m(NaCl)7:1,the dosage of catalyst 7%,reaction temperature 230 ℃,reaction time 3 h,the yield 64.4%.For solvent method,through a large amount of solvent selection,an ideal solvent RJ-X was found.The experimental results show that the suitable conditions are as follows,feeding at room temperature,no catalyst,ratio of urea(g)and solvent RJ-X(mL)1:3,stirring rate 200r/min,reaction time 4h,solvent recycle for 8 times.Under the conditions,the total yield was 79.9% and the purity of product was around 98%.The similarity of Infrared spectrum between product and standard diagram reached more than 95%.Mass spectra and nuclear magnetic spectra effectively verify cyanuric acid product.At the same time,the use of this solvent solved the key problems such as easy metamorphism of solvent and dark color of product.Thus solvent method is more friendly for environment relative to other two kinds of process.Cyanuric acid was applied to preparation of PVC heat stabilizers.The rare earth heat stabilizers were synthesized from cyanuric acid and rare earth metal salts.These heat stabilizers were low toxicity,high efficiency and friendly for environment.The process conditions for the synthesis of three kinds of rare earth heat stabilizers such as lanthanum cyanurate,neodymium cyanurate and cerium cyanurate were optimized.The performance test results for lanthanum cyanurate,neodymium cyanurate,cerium cyanurate and zinc stearate show that the thermal stabilization time of neodymium cyanurate is longest,18.54 min;through the analysis for time-conductivity curve,the induction time of neodymium cyanurate is longest,67 min;through thermogravimetric analysis,the weightlessness ratio of neodymium cyanurate is lowest,89.29%.The above results prove that neodymium cyanurate is a kind of relatively good rare earth stabilizer.