More than 90% of China’s ethylene glycol is used in PET polyester. Currently, the operating load of coal-to-ethylene glycol equipment is only 40%. The contradiction between the rapid increase in domestic coal-to-ethylene glycol production capacity and the overly single downstream application has intensified. However, large-scale polyester enterprises have formed a crude oil-PX-PTA-PET polyester-textile integrated industrial chain layout. There are no industrial opportunities for coal-to-ethylene glycol in the downstream PET industry chain layout. So, coal-to-ethylene glycol will go to Where is the downstream extension?
Amination of ethylene glycol to produce ethylenediamine: still far from industrialization
Ethylenediamine is mainly used in the production of pesticides, medicines and various chemical additives. Ethylenediamine synthesis method There are mainly dichloroethane method, ethanol amination method, ethylene oxide method, ethylene amination method, etc. From the perspective of the reaction principle, the aminoalkylation reaction of ethylene glycol is the most ideal route to prepare ethylenediamine, and the direct production of ethylenediamine from ethylene glycol has become a better process. BASF Europe has disclosed a method for producing ethylene amine and ethanolamine from ethylene glycol, using a two-stage reaction process. The first stage can use all known catalysts, and the second stage uses a catalyst mainly composed of ruthenium and cobalt. , the conversion rate of ethylene glycol is 46%. The one-step method of hydroamination to prepare ethylenediamine is to enter the reactor filled with a catalyst with copper as the main component into aqueous or non-aqueous ethylene glycol and ammonia, and perform a hydroamination reaction to form Ethylenediamine, water, and ethanolamine are by-products. The reaction mixture is separated to obtain the product ethylenediamine.
At present, the process of ammoniation of ethylene glycol to ethylenediamine is not yet mature. The biggest problem is that the catalyst is not stable, has many side reactions, and is difficult to control. It is still far away from industrialization. The distance is large, and the domestic demand for ethylenediamine is not large.
PEN polyester: promising for industrial applications
PEN synthesis route Generally, 2,6-naphthalenedicarboxylic acid and ethylene glycol or 2,6-naphthalenedicarboxylic acid dimethyl ester and ethylene glycol are used as raw materials to synthesize the monomer 2,6-BHEN (2,6- (polyethylene naphthalate), and then undergo a polycondensation reaction to synthesize PEN (polyethylene naphthalate), and finally synthesize high molecular weight PEN through solid-phase condensation polymerization. At present, the technology for industrial or semi-industrial production of PEN has been mastered. Only Mitsubishi Gas Chemical Company of Japan, Amoco Company of the United States and Sumitomo Metal Chemical Company of Japan.
Due to the production of monomer 2,6-naphthalenedicarboxylic acid (2,6-NDA) The process is complex and the production cost is high. There has been no domestic production equipment, and the raw materials and prices have always hindered domestic PEN production and application. PEN is one of the fastest-growing polymer materials in recent years. Its structure is similar to PET, but the difference is that the benzene ring in PET is replaced by a naphthalene ring in the molecular structure of PEN. Since the naphthalene ring has a more stable resonance structure than the benzene ring, the molecular chain is more rigid, and the structure is more planar, its mechanical, electrical, chemical and other properties are better, and it is suitable for industrial use, such as insulating films and food heating. There are prospects in industrial fields such as refill bottles and pharmaceutical packaging films.
1,3 dioxolane: used in combination, it is difficult to have a chance
1,3 dioxolane is an extractant, an electrolytic solvent for lithium batteries, a chlorine-based solvent stabilizer, and the second monomer of polyformaldehyde. The preparation process consists of reacting paraformaldehyde or concentrated formaldehyde with ethylene glycol. have to.
1,3 dioxolane is used as a pretreatment liquid to soak the lithium electrode. The consumption is limited. 1,3 dioxolane is used as the second unit of polyoxymethylene. Specifically, a polyoxymethylene device with an annual output of 40,000 tons requires about 2,000 tons. At present, the domestic polyoxymethylene production capacity is more than 300,000 tons, and 1,3-dioxolane is only 20,000 tons. In order to ensure stable raw material prices and not be controlled by others, polyoxymethylene Formaldehyde production companies are equipped with 1,3 dioxolane. Tangshan Zhonghao Chemical Co., Ltd. is currently launching a 4,000 tons/year 1,3 dioxolane project.
Synthesis of indole from aniline and ethylene glycol: immature technology
Indole is a white crystal and an important fine chemical intermediate. It is an important raw material for the production of spices, printing and dyeing, as well as the prevention and treatment of cardiovascular diseases, neurological diseases, tumors and immunity-enhancing drugs. One of the most important uses is as an intermediate in the synthesis of tryptophan, which can be used as a highly effective feed additive. Indole was originally mainly obtained from coal tar, containing about 2-3% in the 220-270°C fraction. But it is not easy to separate, consumes a lot of energy, and the refining process is complicated.
The synthesis of indole from aniline and ethylene glycol is a new one-step synthesis method of indole developed by Japan in the mid-1990s. This method not only has low raw material prices, but also has a simple operation process. , and there is no waste such as inorganic salts that are harmful to the environment during the reaction. It is the most economical method among many indole synthesis methods. It is obtained by the high-temperature condensation of aniline and ethylene glycol. There are problems in the development of catalysts in China and the required reaction temperature is relatively high, and the technology is not yet mature.
PETG, PCTG copolyester: high monomer synthesis cost
PETG and PCTG are copolyesters formed by the condensation polymerization of terephthalic acid (TPA), ethylene glycol (EG) and cyclohexanediol (CHDM). The addition of CHDM can prevent crystallization and improve processing performance. , improve toughness, transparency and chemical resistance. Copolyesters with CHDM content greater than 50% are called PCTG, and CHDM content is smallFormic acid and formaldehyde are used as methylation reagents to react with ethylenediamine, releasing a large amount of carbon dioxide and formaldehyde gases, which cause greater environmental pollution; ② Use excess sodium hydroxide to react with 1,2-dichloroethane and dimethylamine , which is currently the main process for producing TMEDA in China. The hydrochloride product obtained after the reaction needs to be neutralized with a large amount of alkali to obtain the final product. A large amount of inorganic salt wastewater will be produced during the process, and at the same time, there is a large excess of dimethylamine during the reaction. The cost of wastewater treatment and dimethylamine recovery is too high; ③ Dimethylamine is used as the methylation reagent to react with dichloroethane. The reaction between dimethylamine and dichloroethane is carried out in the presence of N-propylmorpholine. There are many reaction by-products and hydrogen chloride gas is generated at the same time, which causes greater environmental pollution.
The reaction between dimethylamine and ethylene glycol is used. The raw materials are easily available. Tetramethylethylenediamine is synthesized with a metal-supported catalyst in a fixed-bed reactor. However, the catalyst The stability is not good, and more intermediate products are generated at the same time, resulting in a relatively low yield of the process. It is necessary to adjust the ratio of active components within the catalyst to prepare a catalyst with good long-term stability and higher activity.
Ethylene glycol oxidation to glyoxal: overcapacity
Glyoxal is also known as oxalic aldehyde. Most of the products sold on the market are glyoxal aqueous solutions with a concentration of 30%-40%. The solution is a colorless or light yellow transparent liquid. The glyoxal aqueous solution can react with ammonia, amides, aldehydes, The addition or condensation reaction of compounds containing carboxyl groups is the aliphatic dialdehyde with the simplest molecular structure. It is used in textile printing and dyeing, building materials, leather, medicine, pesticides, coatings, etc. There are two main industrial production methods of glyoxal. , namely acetaldehyde oxidation method and ethylene glycol oxidation method. The ethylene glycol oxidation method has the characteristics of simple process equipment, environmental friendliness, high initial product concentration, easy post-processing, and suitable for continuous production. Comprehensive comparison of environmental protection, quality and other factors, the ethylene glycol oxidation method is superior to the acetaldehyde oxidation method. The ethylene glycol oxidation method represents the development trend of glyoxal production. At present, there is excess domestic production capacity of glyoxal. Hubei Luotian Hongyuan Pharmaceutical Technology Co., Ltd., which has the largest domestic production capacity, has started construction of a 100,000 tons/year device this year.
Oxalic acid: one device meets national demand
Oxalic acid is mainly used In industries such as pharmaceuticals, rare earths, metal processing, aluminum products, oxalate esters, and dye intermediates, the sodium formate method consumes a large amount of acid and alkali. The cost of raw materials is high, it is difficult to realize automated operations, and there are many by-products. The coal-to-ethylene glycol unit uses the intermediate product dimethyl oxalate as raw material to produce oxalic acid through hydrolysis, drying, packaging and other processes. It has high selectivity, high yield, simple process, can be produced continuously and on a large scale, and the product purity is high 2010 In May of this year, Inner Mongolia Tongliao Jinmei Chemical Co., Ltd.’s 200,000 tons/year ethylene glycol co-production 100,000 tons/year oxalic acid production unit was launched. Currently, the company is expanding and building an oxalic acid unit with an annual output of 100,000 tons. Shandong Hualu Hengsheng’s oxalic acid plant with an annual output of 100,000 tons started operation at the end of May. On July 31, Ningxia Kunpeng Clean Energy Co., Ltd.’s 200,000 tons/year oxalate ester hydrolysis to produce oxalic acid plant was designed and launched. The company has an annual output of 400,000 tons. The coal-to-ethylene glycol unit is planned to open the entire process on June 30, 2021
At present, the domestic demand for oxalic acid is only about 400,000 tons, and the oxalate ester hydrolysis to oxalic acid reactor Plate reactors are used to meet the requirements for mass and heat transfer. The maximum production capacity of a single reactor (set) can reach 600,000 tons/year. Coal-to-ethylene glycol co-produces oxalic acid. One set of equipment can meet the national demand. . </p
