Method for recovering byproduct ethylbenzene in production of epoxypropane by using co-oxidation method

Abstract

A method for recovering a byproduct ethylbenzene in production of epoxypropane by using a co-oxidation method comprises the following steps: (1) sequentially inputting reaction liquid from a POCHP peroxide section and a hydrogenolysis reaction section into an ethylbenzene heavy component removal tower and an ethylbenzene light component removal tower to remove heavy components and light components so as to obtain an ethylbenzene-rich stream; (2) feeding the ethylbenzene-rich stream obtained in the step (1) into a rectifying tower for azeotropic distillation by taking water as an entrainer and filling a reaction section with a catalyst, taking an ethylbenzene azeotrope formed byethylbenzene in the ethylbenzene-rich stream and water as a tower top material to be extracted from the tower top; enabling the residual 1, 5-dimethyl-2, 4-dioxane to be subjected to ring-opening decomposition under the action of a catalyst in the reaction section, and discharging a decomposition product, together with cyclohexanol, cumene and water from a tower kettle as a tower kettle material; (3) coalescing and separating water from the tower top material obtained in the step (2) to obtain an ethylbenzene product; and (4) coalescing and separating water from the tower kettle material obtained in the step (2) to obtain waste oil, and discharging the waste oil. According to the recovery method, high-purity recovery of the byproduct ethylbenzene can be realized, and the recovery rate is high.

Description

technical field [0001] The invention belongs to the field of organic chemical industry, in particular to a recovery method for by-product ethylbenzene in the production of propylene oxide by co-oxidation. Background technique [0002] Propylene oxide (PO for short), also known as methyl oxirane or propylene oxide, is a colorless, flammable liquid with ether-like odor. Propylene oxide is an important organic chemical raw material. Because of its special -O-C-O-three-membered cyclic ether structure, it has high reactivity, so it can react with various substances. It is widely used in chemical industry, medicine, food, etc. industry has been widely used. At present, propylene oxide is mainly used to produce polyether polyol, propylene glycol, propylene glycol ether, etc., and can also be used to prepare surfactants, demulsifiers, flame retardants, lubricants, pesticide emulsifiers, etc., and its development prospects are very broad. [0003] At present, the methods for produc...

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Problems solved by technology

[0007] At present, in the production process of POCHP to prepare PO, this part of by-product ethylbenzene is generally treated as waste oil, which causes the loss of cumene, increases material consumption, and reduces the overall economic efficiency of the device. Therefore, it is necessary to develop an ethylbenzene resource Recycling method to reduce the unit consumption of cumene

[0008] The content of ethylbenzene in this stock to be recovered is 20-30wt%, and other components are mainly cumene, cyclohexanol, toluene, ethylbenzene, methanol, acetone, 1,5-dimethyl-2, 4-dioxane, etc., in which the relative volatility between cyclohexanol and ethylbenzene is low, so it is difficult to efficiently separate the two by ordinary distillation

The impurity 1,5-dimethyl-2,4-dioxane is an unstable epoxide, which will condense into aldehyde or generate peroxide under long-term storage and heating conditions, which will have a significant impact on product quality , affects the use and takeaway of ethylbenzene, so it must be controlled at a low level, but conventional methods cannot achieve targeted and effective removal, and there is no specific research report so far, which is also the key to recovery of high-quality, low-cost ethylbenzene most difficult problem in

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