Method and system for high-selectivity preparation of dipropylene glycol

Abstract

The invention provides a dipropylene glycol preparation method, which comprises: mixing propylene oxide and propylene glycol to obtain a mixed raw material; and carrying out a condensation reaction onthe mixed raw material obtained in the previous step in a micro-channel reactor to obtain dipropylene glycol. According to the invention, based on the fluid mechanics of the reaction process, particularly the micro-channel reactor is used as the reaction place, and has the characteristic of low channel diameter, so that the raw material is in a laminar flow state in the channel so as to reduce the back-mixing phenomenon, avoid the chance of the contact of the dipropylene glycol and the raw materials 1,2-propylene glycol and propylene oxide, and reduce the occurrence of the cascade reaction, such that the selectivity of the dipropylene glycol in the product is effectively improved; and the preparation method can further effectively reduce the reaction time and improve the yield of the dipropylene glycol product, and is simple in process, mild in condition, easy to control and suitable for industrial mass production.

Description

technical field [0001] The invention relates to the technical field of 1,2-propanediol synthesis, relates to a method and system for preparing dipropylene glycol, and in particular to a method and system for preparing dipropylene glycol with high selectivity. Background technique [0002] Dipropylene glycol, also known as dipropylene glycol, Dipropylene glycol, referred to as DPG), is a colorless, odorless liquid at room temperature, non-corrosive, very small irritation to the skin, low toxicity, and widely used. Dipropylene glycol can be divided into LO+ grade and industrial grade. The former is relatively expensive, and is mainly used in fields requiring high-quality raw materials such as spices, cosmetics, detergents, and food additives; the latter is relatively low in price, and is widely used in the production of industrial solvents and unsaturated resins that do not require high DPG quality. , Raw materials for the production of nitrocellulose varnish, etc. [0003] ...

AI Technical Summary

Problems solved by technology

Although the selectivity of DPG and TPG reaches more than 80%, it is impossible to achieve high-selectivity DPG production

Patent CN 203382693 uses a high-pressure reactor to synthesize crude dipropylene glycol with propylene oxide and 1.2-propylene glycol as raw materials, and then obtains high-quality dipropylene glycol through refining and separation. However, the reaction is intermittent and the utilization rate of the equipment is not high. Not suitable for automatic control

Patents CN203393068 and CN201981142 also use propylene oxide and 1.2-propylene glycol as raw materials, and use continuous reaction technology to solve the defects of cumbersome synthesis process and high energy consumption. However, the series reaction is serious and produces a large number of by-products. Refined recycling

Another example is that patent CN101665414A synthesizes dipropylene glycol with propylene oxide and 1.2-propylene glycol under the condition of no catalyst, but there are long reaction times and defects such as high energy consumption

Therefore, most of the existing production enterprises can only sell crude products with a content of 50% to 80%, and the price of crude products is low, which also reduces the economic benefits of the whole set of devices

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