Study On The Green Synthesis Of 1,6-Hexamethylene Diisocyanate

1,6-Hexamethylene diisocyanate (HDI) is one of the most important materials in polyurethane industry. At present, the main industrial production method is phosgene process in which exists big security risk. Phosgene is highly toxic and easy to cause environmental pollution. Non-phosgene production method of isocyanates has become a hot research at home and abroad with the increasing requirements of environmental protection and sustainable development, such as carbonylation, ester-interchange method and pyrolytic process etc.As the most competitive producing method of HDI,Thermal decomposition method is researched in this paper. Continuous reactor, packed tower was designed according to literature and the reaction characteristics. At the same time, the method of analysis of the products was investigated and HPLC was used. The following is the chromatographic conditions:column temperature 35℃, wavelength of UV detector 205nm, the proportion of mobile phase (methanol to water volume ratio) is 9:1 and flow rate of mobile phase is 0.8ml/min when HDI yield and selectivity are analyzed; the proportion of mobile phase (methanol to water volume ratio) is 55:45 and flow rate of mobile phase is 1.0ml/min. The effect of low boiling solvent and the concentration, catalyst have been also researched. At the same time, the reaction temperature, HDU concentration and flow rate of material have been decided through orthogonal test. The result shows that the best reaction conditions are: reaction temperature 290℃, GIF-1 as the high boiling solvent, GIF-2 as the low boiling solvent, HDU concentration 3.5%, flow rate of material 9g/min, the concentration 15%. Under the condition the conversation percent is 98.9%, HDI yield is 69.4, reaction selection rate is 70.2%.