Technical method for producing dihydric alcohol by catalytic hydration of epoxy compound

Abstract

A process for synthesizing dihydric alcohol by catalyst hydration, the catayst ni the reaction is oxysalt, carbonate or quaternary alkylphosphonium salt of Mo, W, V, the positive ion in the reaction is alkali metal, alkaline earth metal, ammonium salt, quaternar ammonium salt or quaternary alkylphosphonium salt, catalyst usage amount / gross reagent amount is 10-500 ppm, hydration can be taken in high pressure caldron or sequence tube reactor, molar ratio of water and epoxy compound is 1-22:1, reaction temperature is 80-220 deg.C, pressure is 0.2-5.0 MPa, transformation efficient of epoxy compound is 96.00-99.99%, selectivity of single alkylidene group dihydric alcohol is 90-94%.

Description

technical field [0001] The invention belongs to a process for producing dibasic alcohols by catalytic hydration of epoxy compounds. In particular, it relates to a process for producing dibasic alcohols through direct catalytic hydration in a homogeneous phase. Background technique [0002] Alkylene glycols, especially monoalkylene glycols, have a wide range of uses, such as monoalkylene glycols are used as antifreeze, solvents, and raw materials for the production of terephthalates, and finally produce fibers and polyester bottles. [0003] The epoxy compound in the present invention may be ethylene oxide, propylene oxide, butylene oxide, phenyloxirane, and the like. As far as ethylene oxide is concerned, the current industrial production of ethylene glycol is carried out by using a large excess of water and ethylene oxide to react under pressure without a catalyst. The purpose of excess water is to ensure the conversion rate of ethylene oxide and the selectivity of ethyl...

AI Technical Summary

Problems solved by technology

The process conditions of the pressurized hydration reaction are generally: the molar ratio of water to ethylene oxide is 20-28:1, the temperature is 150-220°C, the pressure is 1-10Mpa, the selectivity of ethylene glycol is 88.0-90.0%, The problem is to separate a large amount of water in the product, which not only increases energy consumption, but also reduces the production capacity of the device

[0008] The water-soluble salts of V, Mo, W and other metals are used as epoxy compound homogeneous hydration catalysts, although the water ratio has been reduced and the selectivity of higher monoalkyl glycols has been obtained, but the catalyst is difficult to obtain from the reaction product. Recovery

Due to the large amount of catalyst used, the cost increases, and the solubility of the catalyst in glycol is small, and it is easy to scale on the wall of the rectification device, which brings danger to production.

[0009] US4551566 has also supported vanadate on silica gel, alumina, zeolite or clay, but because vanadate is water soluble, it will be lost from the support to the reactant, so there is still a recovery problem

[0010] In addition, although the existing patented technology reduces the water ratio to 5:1, because the reaction heat of the epoxide hydration reaction is quite high, if it is applied to the adiabatic tubular reactor widely used in the industry, the reaction temperature rise will be too large , the reaction is difficult to control and other problems

To solve this problem, the entire device must be modified, such as adding a heat exchange system to the reactor, which will increase equipment investment