5 production methods of THF
(1) Furfural method:
It is obtained by decarbonylation of furfural to furan and hydrogenation.
This is one of the first methods of industrial production of tetrahydrofuran. Furfural is mainly produced by hydrolysis of agricultural by-products such as corn cob. The law is seriously polluted and is not conducive to large-scale production and has been gradually phased out.
(2) Maleic anhydride catalytic hydrogenation method:
Maleic anhydride and hydrogen enter the reactor containing the nickel catalyst from the bottom, and the ratio of tetrahydrofuran to γ-butyrolactone in the product can be controlled by adjusting the operating parameters. The reaction product and the raw material hydrogen are cooled to about 50 ° C to enter the bottom of the washing tower, and the unreacted hydrogen and gaseous state are separated from the liquid product. The unreacted hydrogen and gaseous products are washed and recycled to the reactor, and the liquid product is distilled to obtain a tetrahydrofuran product. . The process can arbitrarily adjust the ratio of γ-butyrolactone to tetrahydrofuran in the range of 0 to (5:1), the single pass conversion of maleic anhydride is 100%, the selectivity of tetrahydrofuran is 85% to 95%, and the product content is 99.97%. . The process has the characteristics of good catalyst performance, simple process and low investment.
(3) 1,4-butanediol dehydration cyclization method:
The process is as follows: 1087 kg of 22% aqueous sulfuric acid solution is added to the reactor, 1,4-butanediol is added at a rate of 110 kg/h at 100 ° C, and the temperature at the top of the column is maintained at 80 ° C at a rate of about 110 kg / h. An aqueous solution containing 80% tetrahydrofuran was obtained from the top of the column. After the addition of 50 t of 1,4-butanediol, about 70 kg of pyrophoric material was removed from the reactor. The pyrolysis solution is filtered, and the obtained aqueous sulfuric acid solution can be reused, and the yield of tetrahydrofuran in this process can reach 99% or more. Sulfuric acid is the earliest catalyst used in the industrial production of tetrahydrofuran, and it is also a catalyst which is widely used in production today. The process technology is mature, the process is relatively simple, the reaction temperature is low, and the yield of tetrahydrofuran is high, but sulfuric acid is easy to corrode equipment and pollute the environment.
(4) Dichlorobutene method:
It is obtained by using 1,4-dichlorobutene as a raw material, hydrolyzing to form butenediol, and then catalytically hydrogenating. 1,4-Dichlorobutene is hydrolyzed in sodium hydroxide solution, butenediol is formed at 110 ° C, sodium chloride is removed by centrifugation, and the filtrate is concentrated in an evaporative crystallizer to separate the alkali metal carboxylate. High boiling water is removed from the distillation column. The purified butene diol is sent to the reactor, and the butene diol is hydrogenated to form butane diol at a temperature of 80-120 ° C and a certain pressure, and then distilled into a cyclone reactor at atmospheric pressure. And crude tetrahydrofuran is formed in an acidic medium at 120 to 140 ° C, dehydrated and deaerated, and finally distilled to obtain high purity tetrahydrofuran. The method is simple in operation, mild in condition, high in yield, small in amount of catalyst, and can be continuously used.
(5) Butadiene oxidation method:
It is obtained by using butadiene as a raw material, obtaining furan by oxidation, and then hydrogenating. This law has been industrialized abroad.