Study On Treatment Technology Of Toluene Diisocyanate Residue

Toluene diisocyanate(TDI)is a kind of important chemical raw material,which is widely used in the production of polyurethane and its series products.Although China is already a big country in the production and sales of TDI,there are still many shortcomings in the existing production process.The treatment of by-product tar residue in TDI production process is one of the important bottleneck problems to be solved.At present,the treatment of the residue is mainly by burying or burning,both of which will bring environmental pollution and huge waste of resources.Based on the idea of recycling organic components in TDI residues,this article developed three new methods for recycling TDI residues that are simple to operate and low in cost,which can effectively recover resources and reduce environmental pollution.Therefore,it is of great significance for the recycling of solid waste and environmental protection.Three new technologies of TDI residue recycling developed in this work are as follows:(1)Based on the enlightenment of the treatment method of chemical waste liquor by adsorbent,a new process of TDI residue treatment by adsorption method was developed in this work.This process mixes TDI residue with high-boiling ethylene glycol and heats it into a liquid mixture.Adsorption method is used to adsorb macromolecular polymer impurities into the adsorbent,leaving useful organic matter,thereby effectively recovering high-value components.The research results show that the adsorption rate of attapulgite is 23.32%;and the mixed solution after adsorption contains a large amount of triglycerides.(2)Based on the enlightenment of pyrolysis treatment of biomass tar and thermal processing of vacuum residuum in refining industry,a new process of recycling TDI tar residue by pyrolysis method was developed in this work.In this process,the macromolecular polymer of tar residue is split into micromolecular organics,which are separated and purified to achieve the purpose of recycling.The results show that the TDI residue is heated with ethylene glycol and dissolved into a dark brown solution,which is cracked at 350 ?,and the gas-liquid yield can reach 82.74%;When Na OH is used as catalyst in the reaction mixture,the yield of3,3-Diethoxypropane-1,2-diol become much higher.(3)The traditional residue hydrolysis process uses triethylamine as a catalyst and the reaction temperature is 100 ?.In this paper,dolomite is used as a catalyst,and a slightly higher gas-liquid yield(64.26% vs 60.75%)than the traditional hydrolysis method is obtained under normal pressure and reaction temperature of 90 ?.