Tetrahydrofuran production method
In the earliest industrial production, a mixture of saccharaldehyde and vapor was passed into a reactor filled with zinc-chromium-manganese metal oxide (or palladium) catalyst to decarbonize furan at 400-420℃. Then using skeleton nickel as catalyst, tetrahydrofuran was prepared by hydrogenation of furan at 80-120℃.
Tetrahydrofuran production technology
1. Furfural process
Furan is produced by decarbonylation of furfural and hydrogenation, which is one of the earliest methods to produce tetrahydrofuran in industry. Furfural is mainly manufactured by hydrolysis of corn cob and other agricultural and sideline products. The law is highly polluting and not conducive to mass production, and has been phased out.
2. Catalytic hydrogenation of maleic anhydride
The maleic anhydride and hydrogen entered the reactor containing the nickel catalyst from the bottom, and the ratio of tetrahydrofuran to γ-butylactone in the product could be controlled by adjusting the operating parameters. The reaction products and raw hydrogen are cooled to about 50℃ and enter the bottom of the scrubber, so that the unreacted hydrogen and gaseous and liquid products are separated, the unreacted hydrogen and gaseous products are recycled to the reactor after washing, and the liquid products are distilled to obtain tetrahydrofuran products. The process has the characteristics of good catalyst performance, simple process and less investment.
3, 1, 4-butanediol dehydration cyclization
The process is as follows: add 1087kg 22% sulfuric acid aqueous solution to the reactor, add 1, 4-butanediol at 100℃ at the rate of 110kg/h, maintain the top temperature at 80℃, get 80% tetrahydrofuran aqueous solution from the top of the tower at the rate of about 110kg/h. After adding 50t of 1, 4-butanediol, about 70kg coke was removed from the reactor. After the coke is filtered, the solution of sulfuric acid can be reused, and the yield of tetrahydrofuran in this process can reach more than 99%. This process is mature, simple, low reaction temperature and high yield of tetrahydrofuran, but sulfuric acid is easy to corrode equipment and pollute the environment.
4. Dichloroprene method
Butenediol was obtained from 1, 4-dichloroprene by hydrolysis, and then by catalytic hydrogenation. 1, 4-dichloroprene was hydrolyzed in sodium hydroxide solution to produce butenediol at 110℃. The sodium chloride was removed by centrifugation. The filtrate was concentrated in evaporative crystallizer to separate the alkali metal carboxylate, and then the high boiling substance was removed in distillation tower. The refined butenediol was sent to the reactor, nickel as the catalyst, under 80 ~ 120℃ and a certain pressure, butenediol hydrogenation into butanediol, after distillation into the ring reactor, under atmospheric pressure and 120 ~ 140℃ to generate crude tetrahydrofuran in the acidic medium, distillation dehydration and removal of high boiling matter, finally distillation of high purity tetrahydrofuran. This method is simple to operate, mild conditions, high yield, less catalyst consumption, and can be used continuously.
5. Butadiene oxidation method
Using butadiene as raw material, furan was obtained by oxidation and hydrogenation. This method has been industrialized abroad.
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