Thread Content
Achieving pollution-free production throughout the entire process – The isobutylene/tert-butanol method for co-producing MMA/MAO in green petrochemical processes. Author/Source: Sinochem New Network. Date: 2020-03-02. Clicks: 8. Methyl methacrylate (MMA) is an important chemical raw material, serving as a monomer for producing optically transparent materials such as optical fibers and light guide plates. The traditional production method for it is the propiononitrile method. Methyl allyl alcohol (MAO) is a raw material for new types of water reducers, and the traditional production method is the chlorohydrin process. Although the propylene cyanohydrin method and the chlorohydrin method cause severe pollution, they require low investment and have low costs; as a result, most enterprises still use them today. To change this situation and contribute to the green development of the industry, Heze Huali New Materials Co., Ltd. independently developed an isobutylene/tert-butanol-based process for co-producing MMA/MAO, achieving zero pollution throughout the production process; as a result, it was included in the \"List of Green Petrochemical Processes (2019 Edition)\". Co-production of MMA/MAO via the C4 process: Chen Xinjian, chairman of Heze Huali New Materials Co., Ltd., said that the MMA/MAO co-production process they have developed using isobutylene/tert-butanol as raw materials features non-toxic substances both as inputs and as by-products, and it is currently the only green process for MMA/MAO co-production based on the C4 process. According to him, the MMA/MAO co-production process using the isobutylene/tert-butanol method involves using isobutylene/tert-butanol as raw materials, which are oxidized to produce acrolein. Some of this acrolein is further oxidized to yield methacrylic acid, and methacrylic acid reacts with methanol through esterification to form MMA; the other portion of the acrolein is reduced to produce MAO. Chen Xinjian mentioned that the company is committed to becoming an internationally competitive manufacturer of MAO, methacrylic acid, MMA, and their polymers. In addition to this green manufacturing process, the company has undertaken numerous scientific research and development projects at the national, provincial, and municipal levels, and has filed multiple patents; 7 of these are invention patents and 10 are utility model patents that have been granted. Green and environmentally friendly production process According to Chen Xinjian, the processes of producing MMA using the propylene cyanohydrin method and producing MAO using the chlorohydrin method have been **restricted from use. In 2008, the MMA production process using propylene cyanohydrin was classified as a process with high pollution levels and high environmental risks by the Ministry of Environmental Protection in its **Comprehensive List of Environmental Protection Measures**. In the **National Development and Reform Commission’s 2011 Guidelines for Industrial Structure Adjustment**, this process was listed as one that is subject to restrictions. The negative list regarding market access issued by the National Development and Reform Commission and the Ministry of Commerce also includes the MMA production process using propylene cyanohydrin among the processes for which new petrochemical projects are prohibited. Similarly, the chlorohydrin-based MAO process is listed as a process with high pollution and high environmental risk in the \"Comprehensive List of Environmental Protection Measures (2014 edition)\) issued by the Ministry of Environmental Protection. Both of these processes use highly toxic raw materials, pose significant environmental risks, and generate large amounts of wastewater and waste residues that are difficult to treat. Among them, the chlorohydrin method uses highly toxic chlorine as a raw material; 1.4 tons of chlorine are consumed per ton of MAO produced, along with 3 tons of waste hydrochloric acid as a by-product, and more than 10 tons of wastewater containing sodium chloride. These wastewater and waste residues, which contain salts, oils, and chlorine, are extremely difficult to treat. The propylene cyanohydrin method uses highly toxic hydrocyanic acid and highly corrosive sulfuric acid as raw materials, producing over 10 tons of wastewater containing ammonium bisulfate and cyanides per ton of MMA produced. Some companies even sell ammonium bisulfate containing cyanide in these wastewater streams as fertilizer on the market. Compared to these two traditional processes, the isobutylene/tert-butanol method for co-producing MMA/MAO uses isobutylene and tert-butanol as raw materials, which consist of only carbon, hydrogen, and oxygen elements. Air is used as the oxidant and hydrogen as the reductant; no toxic or harmful substances such as chlorine, hydrocyanic acid, or sulfuric acid are employed, resulting in a high atom economy. The process exhaust gases generated are incinerated catalytically to ensure compliance with emission standards; low-concentration wastewater is treated through biological methods, while high-concentration wastewater is sent to an incinerator where it is burned to produce steam as a by-product. There is still room for further promotion in the future. “In terms of production capacity, China’s total annual MMA production capacity is around 1.23 million tons, of which only 340,000 tons are produced using green processes – accounting for roughly one-quarter of the total annual capacity. Therefore, there is significant potential for the expansion of green processes.” ”Chen Xinjian said, “However, due to reasons such as low investment and minimal costs associated with traditional processes, it is difficult to promote green processes.” ” According to him, in recent years several MMA production projects using the propylene cyanohydrin method have been approved; some of these projects even have an annual production capacity of 450,000 tons, with production costs that are lower than those of the green process, which prevents the adoption of this latter approach. Chen Xinjian said that enterprises should not simply regard profit as their sole goal, and suggested that relevant authorities should strictly enforce policies such as the **Industrial Structure Adjustment Catalogue** and the **Comprehensive Environmental Protection Catalogue**, while increasing efforts to promote green manufacturing processes. “In the future, we will continue to pursue technological development, drive the technological upgrading of green processes, and enhance their competitiveness. ”Chen Xinjian said that in the next step, Heze Huali New Materials Co., Ltd. will continue to pursue technological innovation and green development as its goals, thereby promoting the advancement of green manufacturing processes.