【Ten Years of Rapid Development in Chemical Equipment】Pilot-scale calibration completed for the green synthesis process of MDI using the urea method without phosgene by 2240-2025

This technology uses bulk chemicals such as aniline, urea, and formaldehyde as raw materials to produce isocyanates (MDI) through a phosgene-free process, thereby avoiding the use of phosgene and reducing toxic substances and carbon emissions at the source. It is in line with the strategy for the green transformation of the industry, and represents the future direction for MDI production processes. In 2016, this project was listed by the Shaanxi Provincial Department of Science and Technology as part of the “Annual Science and Technology Coordination and Innovation Project Plan”. After nearly 10 years of arduous research, a series of key core technologies were developed, and the core process technology for the green synthesis of MDI via the urea method without phosgene was mastered, featuring independent intellectual property rights. Furthermore, it is reported that this technology enables the development of a comprehensive production process characterized by high atom economy and intrinsic safety, which facilitates the construction of production facilities of various scales as well as the creation of diverse product lines. If industrialization is successful in the future, it will break the global technological monopoly, regional restrictions, and product monopolies associated with the phosgene-based MDI production method. It also offers a Chinese solution for the low-carbon transformation of the global isocyanate industry.

Regarding the synthesis process of MDI, there are two methods for producing MDI (diphenylmethane diisocyanate): the phosgene method and the non-phosgene method. Most manufacturers around the world use the phosgenation method to produce MDI; the main raw materials include benzene, liquid chlorine, and carbon monoxide. The production process involves steps such as the amination of benzene, phosgenation, and subsequent purification. The non-phosgene method is an MDI production method that does not use phosgene as a raw material, and mainly includes methods such as the urea method and the dimethyl carbonate method. The specific steps are as follows: Aniline and urea are added to the reactor in a certain molar ratio; the reaction temperature and time are controlled to produce MDI and the by-product water; finally, separation and purification are carried out to obtain MDI products with high purity. The phosgene-free method in the MDI production process not only avoids the use of phosgene but also reduces environmental pollution and enhances production safety, meeting the requirements of green chemistry. New advances in green synthesis technologies for isocyanates. In China, there are various initiatives aimed at producing isocyanates through green synthesis methods that do not rely on phosgene; to be specific:

Green synthesis technology for TDI using a non-phosgene method: On August 18, 2024, the world’s first pilot-scale plant for the green synthesis of TDI via a non-phosgene method, developed independently by the Shaanxi Coal Technology Center, successfully passed the evaluation and calibration conducted by the Shaanxi Petrochemical Industry Federation. This phosgene-free process for synthesizing TDI uses dimethyl carbonate as a raw material to replace the highly toxic phosgene; it reacts with toluene diamine in the presence of a specially developed catalyst to produce the intermediate toluenediaminomethane (TDC), which is then subjected to pyrolysis to yield TDI. This technology passed the evaluation of scientific and technological achievements organized by the Shaanxi Petrochemical Industry Federation on October 27, 2024. China’s first non-phosgene-based XDI production technology: On August 23, 2024, Lianhong Ruisheng, a subsidiary of Lianhong New Technology, planned to build a facility with an annual production capacity of 4,000 tons of XDI, in order to manufacture high-end products from the XDI series. Lianhong New Technology’s XDI green synthesis technology represents the first domestic method for producing XDI without the use of phosgene, and multiple batches of this product have been tested and evaluated by downstream customers, who have given it their approval. This XDI green synthesis technology offers significant advantages in terms of safety and environmental friendliness; it features mild reaction conditions, readily available raw materials, and low production costs, making it suitable for application in other specialty isocyanate product lines. However, on May 27, 2024, Lianhong New Materials announced that it had acquired the production process technology for XDI products (the XDI green synthesis technology) by paying 49 million yuan (excluding taxes). It is reported that this technology originates from Guoke (Shandong) New Materials and the Institute of Process Engineering, Chinese Academy of Sciences; the patent technology transfer contract signed among the three parties includes a total of 6 patents (target patents) as well as the XDI complete set of technical processes (proprietary technology). Low-carbon production of isocyanates: Additionally, in order to achieve low-carbon production of isocyanates, the Japanese company Toyo Soda has made improvements to its equipment. It has installed new carbon dioxide (CO2) recovery and raw material processing systems at its Nanyo factory in Yamaguchi Prefecture; the captured CO2 is used in the production of isocyanate-based products such as MDI and HDI. This demonstrates the feasibility of low-carbon production of isocyanates. This facility is capable of capturing 40,000 tons of CO2 per year for use in such production, which will significantly reduce the reliance on naphtha and contribute to the development of low-carbon isocyanate products. It is understood that the factory produces 400,000 tons of MDI and 43,000 tons of HDI per year.

【Ten Years of Rapid Development in Chemical Equipment】2241-2025: China’s first deep-processing project for C5 compounds in the coal chemical industry was completed and put into operation in Yulin https://bbs.hcbbs.com/thread-5681588-1-1.html (Source: Haichuan Chemical Industry Forum)