Study On The Green Process Of Hexamethylene Diisocyanate By Decompose Dimethylhexane Dicarbamate

Hexamethylene Diisocyanate(HDI),which is one of the important intermediates in organic intermediates,is mainly synthesized by mature phosgene route in the industrial production.For the highly toxic phosgene as raw material and the highly corrosive by-product hydrochloric acid in the phosgene route,as a result,with the improvement of environmental protection consciousness in peoples'heart,it will be replaced by non-phosgene route.The way of HDI by decompose Dimethylhexane dicarbamate(HDC)is be considered to one of the most promising ways in today.Due to the high boiling solvent with viscosity and dispersion in discovered report,it had a bad effect to yield of HDI and separation.So,a new innovative way was proposed in the dissertation.Under chlorobenzene as low boiling solvent and add pressure,the reactive mechanism?macro kinetics?thermodynamics?select catalytic and process condition ware investigation.The achievements and progresses were exhibited as follow:(1)The process of HDC decompose is analysed by the DTA/DSC synchronous analyzer.The research results show that the HDC decompose to a methanol and a intermediate(HMI),then the HMI is going to decompose to methanol and HDI.With continue to heat up,HDI will occur polymerization and releases CO2 gas.(2)Process condition optimization experiment showed that the optimum conditions were:Co2O3 as catalyst,reaction temperature 230??238?,reaction time 3 h.Under this condition,the conversion of HDC can reach nearly 100%,with yield of HDI as high as 83%?89%,yield of HMI between in 7%?10%.Catalyst can maintain a stable crystal structure and good catalytic property after circle five times.(3)According to the homogeneous reaction kinetics theory,using gas chromatography for HDC pyrolysis process the material fast quantitative detection,the kinetics of HDC to HDI is investigated.Activation energy are 56.94 kJ-mol-1 and 72.07 kJ-mol-1.Refers to the former factor is 2.20×104 min-1 and 1.54×106 min-1.(4)The thermodynamics of HDC is studied in paper by group contribute values method.HDC can't decompose spontaneously in a range of temperature which is adopted in the paper.So we should change some conditions of experiment in order to aim that HDC can decompose.Other more,we can enhance the yield of HDI by transfer product or by-product.