Circulating process for producing propylene oxide by using chlorohydrination method

Abstract

The invention belongs to the field of organic chemical processes, and in particular relates to a circulating process for producing propylene oxide by using a chlorohydrination method. The circulating process comprises the following steps: adding hydrochloric acid into salt-containing wastewater generated in a chlorohydrination reactor, and then removing organic matters in the salt-containing wastewater; then performing evaporation and concentration in an MVR evaporator, filtering concentrated wastewater by virtue of a ceramic membrane and then entering the filtered concentrated wastewater into a diaphragm electrolytic tank for electrolysis to generate chlorine and liquid caustic soda, reacting chlorine with water to generate hydrochloric acid and hypochlorous acid, and then entering hydrochloric acid and hypochlorous acid into the chlorohydrination reactor to perform chlorohydrination reaction with propylene; entering a chloropropanol solution obtained in the chlorohydrination reactor into an extraction tower for extracting chloropropanol in the chloropropanol solution, and entering chloropropanol obtained by extraction into a saponification reactor; reacting chloropropanol in the saponification reactor with liquid caustic soda generated by the diaphragm electrolytic tank by virtue of electrolysis to generate crude propylene oxide, and rectifying to obtain pure propylene oxide. The process disclosed by the invention is reasonable, can achieve the recycling of wastewater and waste residues, and can achieve the closed circulation of salt.

Description

technical field [0001] The invention belongs to the field of organic chemical technology, and in particular relates to a recycling process for producing propylene oxide by chloroalcoholization. Background technique [0002] Propylene oxide (English name Propylene Oxide, referred to as PO), also known as methyl oxirane or propylene oxide, has active chemical properties and is easy to ring-opening polymerization. It can react with water, ammonia, alcohol, and carbon dioxide to generate corresponding compounds or polymer. Propylene oxide is the third largest propylene derivative besides polypropylene and acrylonitrile, and is an important basic organic chemical raw material. Propylene oxide is mainly used in the production of polyether polyols; followed by the production of surfactants, propylene carbonate and propylene glycol. In addition, it is used in propylene glycol ether, hydroxypropyl methylcellulose (HPMC), modified starch, hydroxypropyl acrylate and others. There ar...

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Problems solved by technology

[0008] Domestic propylene oxide manufacturers have carried out concentration and crystallization of propylene oxide saponification wastewater to produce calcium chloride salt, using multi-effect evaporation process. Although multi-effect evaporation saves steam compared with single-effect evaporation, the energy consumption (steam, electricity) is still too large to be economically viable