Method for preparing halogenated propanol and propylene oxide

Abstract

The invention provides a method for preparing halogenated propanol. The method comprises the following step: (1) halogenohydrination: a step of adding hydrogen halide, H2O2 and a catalyst into a reactor, after a period of time, adding propylene, and carrying out a halogenohydrination reaction so as to obtain halogenated propanol. The invention also provides a method for preparing propylene oxide through a halogenohydrination method. The method for preparing propylene oxide is characterized by comprising the step (1) as described in claim 1 of the patent, and also comprising the following steps: (2) saponification: a step of subjecting halogenated propanol in the step (1) and alkali metal hydroxide to a saponification reaction, and carrying out separation so as to obtain propylene oxide and halogenated alkali metal salt; and optionally, (3) electrodialysis: a step of subjecting the halogenated alkali metal salt obtained in the step (2) to bipolar membrane electrodialysis so as to obtain alkali metal hydroxide and hydrogen halide. With the methods provided by the invention, halogenated propanol or propylene oxide can be prepared with high selectivity and yield; meanwhile, the discharge of wastewater and waste residues is greatly reduced.

Description

technical field [0001] The present invention relates to a method for preparing halopropanol, and a method for preparing propylene oxide from halopropanol; more specifically, it provides a method for preparing halopropanol by using propylene as a raw material and adopting a new halohydrin method, and using a new halohydrin Method for preparing propylene oxide. Background technique [0002] Propylene oxide (hereinafter referred to as PO) is an important organic chemical raw material. As the third largest derivative of propylene series, its biggest application is the preparation of polyether polyols, as well as the production of propylene glycol and nonionic surfactants. In recent years, PO is also widely used in the synthesis of green products such as dimethyl carbonate and carbon dioxide polymer. [0003] The production process of propylene oxide mainly includes chloroalcoholization method, co-oxidation method (also called indirect oxidation method) and direct oxidation met...

AI Technical Summary

Problems solved by technology

[0005] The preparation of propylene oxide by the chlorohydrin method of the prior art mainly has the following problems: 1. raw material chlorine and propylene undergo an addition side reaction to generate dichloropropane

Dichloropropane is difficult to utilize and wastes a lot of raw materials

In addition, chlorine gas reacts with propylene to release a large amount of heat, which is concentrated in the reaction vessel, resulting in great production hazards.

②A small amount of oxygen is inevitably entrained in the raw material chlorine gas during the production process. As the reaction proceeds, chlorine gas continuously participates in the reaction, so chlorine gas needs to be continuously replenished, while oxygen cannot participate in the reaction and accumulates in the reaction device continuously. , the oxygen concentration keeps rising, and the reaction releases heat. Oxygen, chlorine, and propylene exist at the same time, and it is easy to cause an explosion at high temperature.

④The reaction produces a large amount of calcium chloride, which leads to high COD of wastewater and pollutes the environment

⑤ The consumption of water resources is large, and a large amount of waste water and waste residues are produced. The production of 1 ton of propylene oxide by the chlorohydrin method produces 40-50 tons of chloride-containing waste water and 2.1 tons of calcium chloride waste. The "five highs" characteristics of high, high COD content and high suspended solids content are difficult to deal with and seriously pollute the environment

⑥ The hypochlorous acid produced in the production process also seriously corrodes the equipment

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