At present, there are three industrial 1,3-PDO production methods: acrolein hydration method, ethylene oxide hydroformylation method and biological fermentation method, among which acrolein hydration method was built by Degussa in 1996 with a capacity of 50,000 tons/ annual industrial device; the ethylene oxide hydroformylation method was built by Shell in 1999 with an industrial device of 72,000 tons/year; the biological fermentation method was built by DuPont in 2006 with an industrial device of 45,000 tons/year; The process includes formaldehyde-acetaldehyde condensation process, ethylene synthesis process via Prins reaction, glycerin chemical process and 3-hydroxypropionaldehyde (3-HPA) one-step synthesis process, etc. Because the biological fermentation method has the advantages of mild reaction conditions, simple operation, few by-products, and excellent selection. Good selectivity, low energy consumption, less investment in equipment, and environmental friendliness have made it a hot spot for development today.
2.1 Acrolein hydration method
The process developed by Degussa Company initially uses a special ion exchange resin catalyst, and adds a chelating functional group containing methyleneimine diacetic acid, reacts at 60 ° C, the conversion rate of acrolein is 82%, and 3-hydroxypropanal ( HPA) selectivity was 80%. Afterwards, 1,3-PDO is obtained by two-stage hydrogenation. When Raney nickel is used as the catalyst, the carbonyl content is reduced from 1000ppm to less than 100ppm. In 1998, Degussa transferred the technology to DuPont.
2.2 Ethylene oxide hydroformylation method
The process developed by Shell is carried out in two steps, that is, firstly, hydroformylation of ethylene oxide and synthesis gas to HPA, followed by hydrogenation to 1,3-PDO. The key to the Shell process is the use of cobalt carbonyl catalysts in the hydroformylation process, and the use of various ligands (such as diphosphine, trihydrogen phosphine, arsenic, etc.) base pyridine, etc.), based on ethylene oxide, the yield of 1,3-PDO can reach 85% to 90%, and the product purity can reach 99.6% (mass ratio).
2.3 Biological fermentation method
The method includes the selection of raw materials, fermentation process, removal of bacteria and protein, desalination and rectification.
Since the 1,3-PDO fermentation process includes microbial strains, proteins, nucleic acids, polysaccharides, inorganic salts, organic acid salts, glycerin, 2,3-butanediol, water, etc. in addition to the target product, it is a very complicated process. components, and 1,3-PDO has strong polarity and low concentration in the fermentation broth (about 50-110 g/L in one stage), so it is very difficult to separate and recover 1,3-PDO from the dilute solution, which is also a constraint on biological The key to 1,3-PDO production. In order to solve the many problems existing in the whole separation process, the purification process needs to be further optimized, especially to develop an economical and efficient separation method, while improving the yield and quality of 1,3-PDO, simplify the process route, reduce energy consumption, and recover A by-product with higher added value in the fermentation broth.
In addition to biological synthesis of 1,3-PDO, the chemical synthesis of 1,3-PDO from glycerol is also worthy of attention. For example, the research group of Tohoku University in Japan and Daicel Corporation have developed a 1,3-PFO process from biodiesel by-product glycerol. The process uses a powder-type Ir-ReOX/SiO2 catalyst, which is dispersed in the reaction solution, and the selectivity of 1,3-PDO reaches 60%. The research group also confirmed the reaction mechanism for the formation of 1,3-PDO via the 2,3-=hydroxypropanol intermediate. The research team also enabled the reaction to take place in a fixed-bed reactor by using an optimized spherical catalyst supported on silica gel. It has been continuously operated on a laboratory scale for more than 300 hours, showing that the catalyst can still maintain high activity and selectivity. Therefore, it can be considered that the scale-up test of the industrial route can be carried out, and the reaction by-product propanol can also be sold as a solvent. 3 Domestic and foreign market supply and demand and forecast
In recent years, foreign countries have seldom reported new 1,3-PDO production facilities. It is estimated that the current production capacity is 265,000 tons/year, the largest of which is Shell’s ethylene oxide hydroformylation unit in Geismar, Louisiana, USA, with a capacity of 136,000 tons/year; Degussa’s Weser, Germany There are two sets of acrolein hydration plants with a production capacity of 18,000 tons/year and 50,000 tons/year in the Wesseling area. DuPont has a 18,000 tons/year acrolein hydration plant in Germany and a set in Tennessee, USA. The bio-fermentation device of the company has a current production capacity of about 60,000 tons/year after a 30% capacity expansion in 2011. Shell has predicted that the demand for PTT, the main downstream product of 1,3-PDO, is expected to reach 1 million tons in the next few years, and the required 1,3-PDO will reach 360,000 tons. Obviously, the existing production capacity cannot meet the market demand.
At present, my country’s annual consumption of PTT has exceeded 30,000 tons, accounting for about 10% of the world’s total consumption. 90% of PTT consumption is directly used for spinning as fiber, and the remaining 10% is used for engineering plastics, of which about two-thirds of the fiber is used for clothing and one-third for carpets. In the next few years, the domestic PTT potential market demand will be 50,000-100,000 tons.
