Butyl Glycol CAS 110-63-4

Also known as acetylenic aldehyde method, this process is a traditional method for producing BDO, and is divided into classical method and improved method.

(1) Classical method

At high pressure (13.8-27.6 MPa) and 250-350 °C, acetylene is reacted with formaldehyde in the presence of a catalyst (usually cuprous acetylene and bismuth on a silica support), and then the intermediate is separated by Raney nickel catalyst. The typical theoretical yield of the whole process (calculated as acetylene) is 91% by hydrogenation of l,4-butynediol to BDO. The characteristic of the classical method is that the catalyst and product do not need to be separated, and the operating cost is low. However, the partial pressure of acetylene is high, and there is a danger of explosion. The safety factor of the reactor design is as high as 12 to 20 times, the equipment is large and expensive, and the investment is high; shortening and yield reduction.

(2) Improvement method

In the first step, acetylene and formaldehyde are placed in a reactor composed of several medium-slurry bed reactors in series, and an improved Cu catalyst is used to react at 79-90 ° C and 0.12-0.13 MPa to form butynediol. After filtration, the catalyst and the reactant are separated and left in the reactor, and the liquid-phase material flows out of the reactor for purification and enters the next reactor. The conversion rate of formaldehyde in this reaction was 98%, and the yield of 1,4-butynediol was 95%.

In the second step, a modified Pd/C catalyst is used in the slurry bed, and butynediol is hydrogenated at 60-70 °C and 2.0-2.5 MPa to form butenediol and BDO, and then in a packed reactor, with Ni is used as a catalyst to hydrogenate butenediol to form BDO at 120-150 ℃. Finally, BDO is purified by distillation and thin-film evaporation, and the purity of BDO is ≥99%. The technical characteristics of the improved method are:

a. Using an improved Cu catalyst, low-pressure operation, the decomposition pressure of acetylene itself does not exceed 0.14MPa, which simplifies the additional safety facilities and saves the high-pressure container and compressor;

b. The reactor is equipped with a special filtration system to facilitate the separation of catalyst and reactant in the reactor;

c. Butynediol is hydrogenated to form butenediol and BDO by using an improved Pd/C catalyst, and butenediol is converted to BDO by hydrogenation using Ni as a catalyst;

d. The feed composition is flexible, the formaldehyde content in the formaldehyde solution can be 2-10%, and the acetylene feed does not need to be diluted with inert gas. It is estimated that the operating cost and investment are reduced by 10-20% compared with the classical method.

The process was successfully developed by Japan’s Mitsubishi Chemical Corporation in the 1970s. Do it in 3 steps:

(1) Using Pd-Te/activated carbon as a catalyst at a temperature of 60 °C and a pressure of 6.9 MPa, butadiene undergoes an acetyl oxidation reaction with acetic acid and oxygen to generate 1,4-ethylenediacetoxy in a fixed bed reactor base-2-butene;

(2) Under the same temperature and pressure, the reaction solution after removing acetic acid is catalytically hydrogenated in a fixed-bed reactor to generate 1,4-ethanediacetoxybutane;

(3) BDO and 1-acetoxy-4-hydroxybutane are obtained by hydrolysis with cation exchange resin, and the latter is cyclized into THF by deacetoxylization with ion exchange resin. Typical theoretical yields (based on butadiene) are 80% to 85%. The technological characteristics of the method are that the raw material used is rich in resources, there is no potential safety hazard, and the yield of intermediate products and products is high; changing the hydrolysis conditions can adjust the production ratio of BDO and THF.

The process was developed by the Japanese Kuraray Company, and Lionel, which mainly produces propylene oxide, obtained the patent license of the technology and built a factory in Texas, USA. The process route is as follows: propylene oxide catalyzes isoformation of allyl alcohol, hydroformylation of allyl alcohol in the presence of a rhodium catalyst, and hydrogenation of the product in the presence of a Raney nickel catalyst to form BDO, with a typical theoretical yield of 93% . The process has low investment, simple process, high utilization value of by-products, rhodium-based catalyst can be recycled, long life, high yield of Butyl Glycol, low steam consumption, hydroformylation and hydrogenation are liquid-phase reactions, changing the process load Easy, characteristics such as Butyl Glycol output can be adjusted according to the market. The economics of the process depend to a large extent on the price of the raw material propylene oxide.

The process is a production method combining the gas-phase oxidation method for producing maleic anhydride from n-butane and the hydrogenation technology of maleic anhydride. The n-butane is oxidized under the catalyst of vanadium and phosphorus mixed oxide to generate maleic anhydride, which is then quenched with water to obtain maleic acid, which is then catalytically hydrogenated in a fixed bed reactor to generate BDO. This process eliminates the dehydration, purification and esterification processes of maleic anhydride, and reduces the main process from 8 to 4, thus shortening the entire process, reducing the number of equipment, reducing investment costs by 20%, and saving production costs by 25～ 40%. The process has few by-products, and almost all maleic anhydride can be converted into BDO. In the process of hydrogenation, recovery and purification, THF can also be produced by properly adjusting the process conditions.

The Ding Yi has three steps:

(1) Under the action of a catalyst, n-butane is oxidized into maleic anhydride by air, and then under the action of a catalyst, the maleic anhydride undergoes an esterification reaction with ethanol to generate diethyl maleic anhydride;

(2) Diethyl maleic anhydride is hydrogenated under the action of a catalyst to generate BDO, γ-butyrolactone and THF;

(3) Separation and purification of reaction products. By adjusting the process conditions, the ratio of BDO, γ-butyrolactone and THF can be changed.

The BDO production of this process has a cost advantage, so many new devices have been constructed using this process in recent years, which is also the main development trend of the BDO production process.