Replace phosgene with dimethyl carbonate and build the world's first pilot plant
The phosgene technology, which is commonly used in the global production of toluene diisocyanate (TDI), is expected to revolutionize it. On October 27, the process technology of dimethyl carbonate synthesis TDI independently developed by Shaanxi Coal Industry (25.070, -0.18, -0.71%) Chemical Technology Development Center Co., Ltd. passed the scientific and technological achievement appraisal organized by Shaanxi Petroleum and Chemical Industry Federation in Xi'an. The appraisal committee headed by Lv Jian, academician of the Chinese Academy of Engineering and researcher of Xi'an Institute of Modern Chemistry, believes that the technology is at the international advanced level and can replace the traditional phosgene method, and it is recommended to increase the process of technology industrialization.
The non-phosgene synthesis of TDI process technology uses dimethyl carbonate as raw material to replace the highly toxic phosgene, and the intermediate product methyl toluene dicarbamate (TDC) is generated with toluene diamine under the action of a self-developed special catalyst, and then TDI is prepared by pyrolysis. The main process includes four sections: synthesis, separation, water washing and pyrolysis.
Song Shuangtian, chairman of Shaanxi Coal Chemical Technology Development Center Co., Ltd., introduced that they carried out research on non-phosgene TDI green synthesis process in Shaanxi Coal Chemical Group Co., Ltd. as early as 2014, and in 2015, it was listed as "Shaanxi Province 2015 Science and Technology Co-ordination Innovation Project Plan" project by Shaanxi Provincial Department of Science and Technology. After 10 years of hard work, we have successfully developed synthetic catalysts and pyrolysis catalysts, and mastered the core process technology of the whole process of non-phosgene TDI green synthesis with independent intellectual property rights. In August 2020, Shaanxi Coal Technology Center built the world's first non-phosgene TDI pilot plant in the Huazhou test base in Shaanxi, and then after many feeding tests and optimization transformation, the process flow was opened in October 2023 and the target product TDI was obtained, marking a revolutionary technological leap in the polyurethane industry and opening up a new process route.
The 72-hour assessment results organized by the Shaanxi Petrochemical Federation in August this year showed that the pilot plant was running smoothly, the indicators reached or exceeded the expected goals, and the TDI products met the national standards after third-party inspection. Compared with the traditional phosgene route, this new green synthetic TDI technology replaces highly toxic phosgene, reduces safety risks, does not produce hydrochloric acid, and reduces the emission of "three wastes".
It is reported that toluene diisocyanate is an important organic intermediate, used in the manufacture of polyurethane foam, with the advantages of flame resistance, low temperature resistance, wear resistance and high insulation, and is widely used in aviation, vehicles, ships, refrigeration and coatings, adhesives, sealants and other fields. At present, TDI production at home and abroad is the phosgene process, that is, carbon monoxide and chlorine are used as raw materials to produce phosgene, and then reacted with toluene diamine to produce TDI. Although the production technology is mature, phosgene and chlorine are highly toxic gases, especially phosgene is more dangerous, and there are problems such as environmental pollution, equipment corrosion, and residual chlorine affecting product quality.
Source: Sinochem Xinnet
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