This project belongs to the field of chemistry and chemical industry. Methyl methacrylate (MMA) is an important organic chemical raw material and is widely used in military, construction, rubber, plastics, daily chemicals and other fields. In recent years, as downstream applications continue to expand, demand for MMA has grown rapidly, but the domestic self-sufficiency rate is only 60%.
The traditional MMA production process is the acetone cyanohydrin (ACH) method. Hydrocyanic acid and excessive concentrated sulfuric acid are used in the production process, which is environmentally unfriendly and costly. Based on the successful development of oxidation of propylene to acrylic acid, Japanese companies have developed a new process for synthesizing MMA from isobutylene after more than 20 years of research. Compared with the ACH method, this route uses cheap C4 as raw material, has high atomic yield, is environmentally friendly, has advanced technology, and has better economic and social benefits. However, the C4 method is very difficult, whether it is two-stage catalyst development or process development. So far, the complete set of technology is only in the hands of a few Japanese companies, and technology monopoly is exercised outside. Since the domestic research on this route in the 1980s, key technologies have not yet been broken through.
As a leading domestic enterprise in the production of acrylic acid and esters, the project organizer has won 1 second prize in the National Science and Technology Progress Award, 1 first prize in Shanghai City Technological Invention Award and 2 first prizes in scientific and technological progress. On this basis, the company seized the opportunity to carry out more challenging research on C4 legal MMA technology, mastered a complete set of core technologies, developed a complete set of MMA production technologies with independent intellectual property rights for the first time in China, and built a 2500 tons/year MMA demonstration device, all indicators have reached the international advanced level.
This project has obtained the core invention technologies: 1) For the first-stage catalyst, the introduction of element Yb improves the migration ability of lattice oxygen; the citric acid complex method is used to prepare the catalyst, so that the catalyst has a uniform active site distribution and an ideal pore structure, which reduces the negative effect of diffusion on the reaction;2) For the second-stage catalyst, a low-temperature synthesis method is used to improve the performance of the catalyst; The regeneration method of adding ammonium salt to the deactivated second-stage heteropolyacid catalyst completely restores the structure and performance of the catalyst;3) For the first time, silicon powder, a high thermal conductivity material, is used as the catalyst carrier, which improves the thermal conductivity of the catalyst and reduces the catalyst hot spot temperature and suppresses deep oxidation;4) A mixed solvent is invented as a high-efficiency extractant, which improves the extraction rate of MAA; 5) Invented the application of falling film crystallization technology to the refining process of high-purity MAA, and the product is superior to chemical methods in terms of purity and chromaticity indicators; 6) Invented a composite polymerization inhibitor and separation equipment suitable for the production process of methacrylate (ester), effectively inhibiting polymerization and ensuring safe and stable operation of production.
Based on the inventions of the above key technologies, this project has achieved the following results: (1) The unit consumption of isobutylene in the C4-based MMA complete set technology is 0.888 tons/ton of MMA, which is superior to similar technical levels in Japan;(2) The sales price of the catalyst is only 1/2 of that of Japanese catalysts, and after the deactivated catalyst is regenerated, the cost is further reduced;(3) The purity of the MMA product is more than 99.95 wt %, reaching the optical grade PMMA raw material index, which is recognized by downstream high-end users;2013~In 2015, the 2500-ton/year industrial demonstration plant achieved profits and taxes of more than 14 million yuan.
In view of its advantages in comprehensive catalyst performance and production process technology, our company has cooperated with Shandong Yuhuang Chemical Co., Ltd., and the first domestic MMA unit with independent intellectual property rights under construction will be put into operation in 2017, which can generate hundreds of millions of yuan in profits and taxes every year; in addition, it has reached cooperation intentions with many companies to actively promote and apply technology. The research results of this project cover catalysts and complete process technologies. 24 China invention patents have been applied, of which 20 are authorized; 19 foreign invention patents have been applied, of which 5 are authorized.
To sum up, the research results of this project have filled domestic gaps and broken foreign technology monopoly, making China the second country in the world after Japan to have complete production technology for preparing MMA by C4 method.