Method for coproducing cyclohexanol and alkanol

Abstract

The invention provides a method for coproducing cyclohexanol and alkanol. The method comprises the following steps: preparing benzene and/or cyclohexane into cyclohexene, carrying out addition-esterification on the cyclohexene in a catalytic distillation tower, obtaining carboxylic acid/ cyclohexyl carboxylate material flow at the bottom of the tower, hydrogenating the material flow to obtain the cyclohexanol and the alkanol. The esterification and hydrogenation reactions in the method have high conversion rate and selectivity, and high atom economy; the process is environment-friendly; the alkanol is coproduced when the cyclohexanol is produced, in particular, when acetic acid is used, the cheap acetic acid is converted into ethanol with high cost and large market capacity in an indirect manner, so as to increase the economical efficiency of the process.

Description

technical field [0001] The invention relates to a method for co-producing cyclohexanol and alkanol, and also relates to a method for producing cyclohexanone and a method for producing caprolactam. Background technique [0002] Both cyclohexanol and ethanol are important chemical raw materials and solvents. Cyclohexanol is mainly used for dehydrogenation of cyclohexanone, and cyclohexanone is not only the main intermediate for the further production of nylon 6 and nylon 66, but also widely used in paints, pesticides, dyes, aviation lubricants, grease, wax, Solvent for film removal, decontamination, spot removal, etc. Ethanol is not only a raw material for synthetic esters and other chemical products, but also widely used as a fuel additive for gasoline. [0003] The method of industrially synthesizing ethanol is mainly the direct hydration method of ethylene, but in some countries rich in agricultural and sideline products, the fermentation method is still the main method o...

AI Technical Summary

Problems solved by technology

[0009] The first disadvantage of the cyclohexane oxidation method is that cyclohexanol (ketone) is more easily oxidized than cyclohexane, so in order to ensure a certain selectivity, the conversion rate of cyclohexane must be controlled at a very low level , a large amount of unreacted cyclohexane needs to be separated by distillation and re-oxidized, which greatly increases the energy consumption of the whole process

The second shortcoming that cyclohexane oxidation method exists is: even if the conversion ratio of cyclohexane is controlled at a low level, still produce quite a lot of low-value by-products in the reaction process, not only reduces the yield of product, but also Increased difficulty in separating products

The third disadvantage of the cyclohexane oxidation method is that the organic by-products produced during the oxidation process are very complex and can only be removed by alkaline washing. The resulting large amount of waste lye not only has a COD value of up to 10 5 ~10 6 mg / L, and not biodegradable, it is still a worldwide environmental problem

[0012] However, the method of Asahi Kasei still has the following deficiencies

[0013] (1) There are thermodynamic limitations in the direct hydration of cyclohexene, and the solubility of cyclohexene in water is very small. The hydration reaction mainly occurs at the two-phase interface, which leads to a slow rate of cyclohexene hydration reaction and a single-pass conversion rate. Very low, such as adopting high-silicon ZSM-5 catalyst, staying in two series slurry reactors for 2h, the conversion rate of cyclohexene is only 12.5%. Separation from the product stream for recycling, which significantly increases the energy consumption of the process

[0014] (2) It is necessary to use high-purity cyclohexene as a raw material, otherwise, due to the dilution of other components, it will lead to more recycled materials and lower reaction efficiency. However, cyclohexene is prepared by partial hydrogenation of benzene, In addition to cyclohexene, the product stream also contains a considerable amount of cyclohexane and benzene. The boiling points of these three are very close, making the purification of cyclohexene very difficult.

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