THF

Preparation method:

1. One of the pioneering methods in the industry to produce tetrahydrofuran is through the furfural process, which involves the decarbonylation of furan to obtain furfural and its subsequent hydrogenation. Furfural is primarily derived from corn and other agricultural and sideline products through hydrolysis. However, this method has gradually phased out due to its adverse environmental impact and limited suitability for large-scale production.
2. To catalytically produce tetrahydrofuran from maleic anhydride, a reactor is employed where maleic anhydride, hydrogen, and a nickel catalyst are combined. The ratio of tetrahydrofuran to γ-butyrolactone, the desired product, can be controlled by adjusting the operating parameters. The reaction product and the unreacted hydrogen undergo cooling and separation in a scrubber, where the gaseous components are isolated from the liquid product. The unreacted hydrogen and gaseous products are recycled back to the reactor, while the liquid product undergoes distillation to obtain pure tetrahydrofuran. This process allows for the flexible adjustment of the γ-butyrolactone and tetrahydrofuran ratio within the range of 0 to 5:1, achieving a 100% conversion rate of maleic anhydride and a tetrahydrofuran selectivity of 85% to 95%. The resulting product exhibits a remarkable purity of 99.97%. This process offers advantages such as excellent catalyst performance, simplicity, and low investment requirements.
3. The 1,4-butanediol dehydration cyclization process involves introducing a 22% sulfuric acid aqueous solution weighing 1087 kg into a reactor. Subsequently, 1,4-butanediol is gradually added at a rate of 110 ℃/h at a temperature of 100 ℃ while maintaining the top temperature of the column at 80 °C. This process yields an aqueous solution containing 80% tetrahydrofuran, collected from the top of the queue at approximately 110 kg/h. Once 50 tons of 1,4-butanediol have been added, around 70 kg of the mixture is removed from the reactor. The resulting filtrate is filtered, and the aqueous sulfuric acid solution obtained can be recycled. This process achieves a tetrahydrofuran yield exceeding 99%. Sulfuric acid catalyzes the industrial production of tetrahydrofuran and remains the catalyst of choice in present-day production. Although this technology is well-established and relatively simple, it requires low reaction temperatures and offers high tetrahydrofuran yields. It is important to note that sulfuric acid in this process corrodes equipment and poses environmental pollution risks.
4. The dichlorobenzene method utilizes 1,4-dichlorobutylene as the raw material, which undergoes hydrolysis to produce butylene glycol, followed by catalytic hydrogenation. In the hydrolysis step, 1,4-dichlorobenzene is treated with a sodium hydroxide solution at 110 °C, forming butylene glycol. The sodium chloride is separated through centrifugal separation, and the filtrate undergoes concentration through evaporation and the removal of alkali metal carboxylate in a distillation column. The refined butene diol is then introduced into a reactor, which reacts at a certain pressure and temperature range of 80 to 120 °C. This hydrogenation step converts butylene glycol into butanediol, distilled into a cyclization reactor. Crude tetrahydrofuran is formed at temperatures of 120 to 140 °C in an acidic medium, followed by distillation for dehydration and the removal of high boiling materials to obtain high-purity tetrahydrofuran. This method offers simplicity, operates under mild conditions, achieves high yield, and requires minimal catalyst usage. Additionally, it allows for continuous utilization.
5. The butadiene oxidation method employs butadiene as the primary raw material, which undergoes oxidation to furan and subsequent hydrogenation. This method has already been industrialized abroad.
6. the first sugar aldehyde is the raw material in industrial production. The aldehyde is mixed with steam and fed into a reactor containing a zinc-chromium-manganese metal oxide catalyst (or palladium). Under specific 400-420 °C conditions, the carbonyl group is removed, yielding furan. The furan is then hydrogenated at 80-120 °C using a skeleton nickel catalyst to produce tetrahydrofuran. Producing 1 ton of tetrahydrofuran requires approximately 3 tons of polysaccharide consumption. Multiple production methods exist, including the mature catalytic dehydration ring method utilizing 1,4-butanediol, known as the lei method (Reppe method), where butanediol is derived from acetylene and formaldehyde. Another method is dichlorobenzene, where tetrahydrofuran is produced as a by-product of 1,4-dichlorobenzene derived from chloroprene rubber monomer. In recent years, the catalytic hydrogenation of maleic anhydride using it as the raw material has also gained development and industrial interest.
7. Furfural can be catalyzed by zinc oxide, chromium oxide, and manganese dioxide for decentralization. Additionally, furfural can undergo hydrogenation to produce tetrahydrofuran in the presence of a nickel-aluminum catalyst.