Method for preparing propylene glycol monomethyl ether acetate (PMA) by continuous reaction and distillation

Abstract

The invention discloses a method for preparing propylene glycol monomethyl ether acetate (PMA) by continuous reaction and distillation. The method comprises the following steps of: mixing propylene glycol methyl ether and acetic acid serving as raw materials in a mol ratio of 1 to 1, and preheating the mixture; allowing the mixture to enter a fixed bed reactor for pre-reaction and then enter an esterification reactor for temperature raising and further reaction; performing rectification, condensing and phase-splitting on the gasified reaction crude product to obtain an oil phase and a water phase; refluxing a part of the upper-layer oil phase to an esterification tower top and the rest to a crude ester jar for preliminary treatment and then light components removal treatment; refluxing a part of the collected lower-layer water phase to the esterification tower top and allowing the balance to the recovery section for treatment, wherein the catalyst for the fixed bed reaction is sulfonyl strongly acidic ion-exchange resin; and the catalyst for the esterification reactor is one of sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid and mixed catalyst A. The method realizes the continuous and pollution-free production of the PMA.

Description

technical field [0001] The present invention relates to a kind of production method of propylene glycol monomethyl ether acetate (PMA) prepared by continuous reaction rectification. Specifically, propylene glycol monomethyl ether acetate (PMA) is prepared by continuous reaction rectification under an acidic catalyst using propylene glycol monomethyl ether and acetic acid as raw materials. ). Background technique [0002] Propylene glycol methyl ether acetate (PMA) is a low-toxic high-grade industrial solvent with excellent performance. Since PMA has two groups with strong solubility functions-ether bond and hydroxyl group, the former is lipophilic and can dissolve hydrophobic compounds, and the latter is hydrophilic and has strong solubility for polar and non-polar substances. In addition, PMA also has the characteristics of good thermal stability, small viscosity change, high foaming and low corrosion, so it is widely used in coatings, inks, cleaning agents, printing, text...

AI Technical Summary

Problems solved by technology

[0004] 1) The reaction time is long, the reaction by-products are more, and the yield is not high;

[0005] 2) The problem of equipment corrosion is still relatively obvious, resulting in high equipment maintenance costs;

[0006] 3) The reaction often requires the use of water-carrying agents, and water-carrying agents are currently common: benzene, toluene, xylene, cyclohexane, etc., but it is still easy to entrain 5-10% of the reactants, and the water-carrying agent is in production It will be very harmful to human health and easily pollute the environment;

[0007] 4) The reaction product needs to be neutralized, the operation is cumbersome, and causes problems such as high unit consumption of acetic acid and catalyst loss;

[0008] 5) Precipitations such as catalysts and acetates are likely to cause blockage of pipes and fillers, affecting operation and troublesome equipment maintenance

[0009] In short, the low yield, heavy corrosion, and high material and energy consumption of the traditional batch esterification process have greatly restricted the promotion and production of PMA, and also affected the market benefits of PMA.

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