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 path for downstream extension?
Amination of ethylene glycol to produce ethylenediamine: still far from industrialization
Ethylenediamine is mainly used in pesticides, medicines and various chemical additives In the production of ethylenediamine, the main synthesis methods include 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 stability of the catalyst is poor, there are many side reactions, and it is difficult to control. There is still a long way to go before industrialization. Moreover, the domestic ethylene glycol ammonia production process is not yet mature. Domestic demand for diamine is not large either.
PEN polyester: promising for industrial application
The PEN synthesis route generally uses 2,6-naphthalenedicarboxylic acid and ethylene glycol or 2,6-naphthalenedicarboxylic acid dimethyl ester and Ethylene glycol is used as raw material to synthesize the monomer 2,6-BHEN (ethylene glycol 2,6-naphthalenedicarboxylate) through esterification or transesterification reaction, and then synthesizes PEN (polyethylene 2,6-naphthalenedicarboxylate) through polycondensation reaction. Diol ester), and finally high molecular weight PEN is synthesized through solid-phase condensation polymerization. Currently, only Mitsubishi Gas Chemical Company of Japan, Amoco Company of the United States and Sumitomo Chemical Company of Japan have mastered the technology of industrial or semi-industrial production of PEN.
Due to the complex production process and high production cost of monomer 2,6-naphthalenedicarboxylic acid (2,6-NDA), there has been no domestic production equipment and raw materials And price has been stuck in 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: It is rare to have a chance to use it in conjunction with it
1,3 dioxolane is an extractant, an electrolytic solvent for lithium batteries, and a chlorine-based solvent stabilizer , the second monomer of polyformaldehyde, the preparation process is prepared by reacting paraformaldehyde or concentrated formaldehyde and ethylene glycol.
1,3 dioxolane is used as a pretreatment liquid to soak the lithium electrode, and the consumption is limited. 1,3 dioxolane is used as the second monomer of polyformaldehyde, with an annual output of 40,000 A ton polyformaldehyde device requires about 2,000 tons. At present, the domestic polyformaldehyde 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, polyformaldehyde production companies have supporting 1 ,3 dioxolane, Tangshan Zhonghao Chemical Co., Ltd. is currently launching a 4,000 tons/year 1,3 dioxolane project.
The synthesis of indole from aniline and ethylene glycol: the technology is immature
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Indole is a white crystal and is 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 method for the one-step synthesis of indole developed in Japan in the mid-1990s. This method not only has low raw material prices and simple operation processes, but also does not have any side effects in the reaction. The generation of wastes such as inorganic salts that cause environmental harm 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 and PCTG copolyester: high monomer synthesis costs
PETG and PCTG are terephthalic acid (TPA), ethylene glycol (EG) and cyclohexanediol ( It is a copolyester formed by the condensation polymerization of CHDM. The addition of CHDM can prevent crystallization, while improving processing performance, toughness, transparency and chemical resistance. Copolyesters with CHDM content greater than 50% are called PCTG, and copolyesters with CHDM content less than 50% are called PETG. Compared with PET, the biggest feature of PETG/PCTG is that it conforms to the concepts of environmental protection and food FDA certification. The molded products have excellent transparency, toughness, chemical resistance and easy processing, and can be used in food contact, cosmetic packaging, medical equipment and Pharmaceutical packaging applications. Currently, the production cost of monomer 1,4-cyclohexanedimethanol (CHDM)The hydroxylation reagent reacts with dichloroethane, and the reaction between dimethylamine and dichloroethane is carried out in the presence of N-propylmorpholine. The reaction has many by-products and generates hydrogen chloride gas at the same time, which causes greater environmental pollution.
Using the reaction of dimethylamine and ethylene glycol, the raw materials are easily available. In a fixed-bed reactor, a metal-supported catalyst is used to synthesize tetramethylethylenediamine. However, the stability of the catalyst is not good, and at the same time, tetramethylethylenediamine is produced. More intermediate products are produced, 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 with a concentration of 30%-40%. Aqueous solution. This solution is a colorless or light yellow transparent liquid. Glyoxal aqueous solution can perform addition or condensation reactions with ammonia, amides, aldehydes, and carboxyl-containing compounds. It is the simplest aliphatic dihydric aldehyde 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 set of equipment meets national demand
Oxalic acid is mainly used in pharmaceutical, rare earth, metal processing and aluminum products, oxalate esters, dye intermediates and other industries. The sodium formate method consumes a large amount of Acid and alkali have high raw material costs, are difficult to automate, and have 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 scheduled to open the entire process on June 30, 2021
Currently, the domestic demand for oxalic acid is only about 400,000 tons. The oxalate hydrolysis to oxalic acid reactor uses a plate reactor. 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, and one set of equipment can meet the national demand. </p
