Preparation method of dimethyl phthalate (DMP)

Abstract

The invention discloses a preparation method of dimethyl phthalate (DMP). The preparation method comprises the following steps: adding the raw materials including phthalic anhydride and superfluous methanol to a reaction kettle, adding concentrated sulfuric acid as a catalyst, controlling the temperature in the reaction kettle to be 0-150 DEG C, reacting for 16-20 hours, neutralizing the catalyst and unreacted phthalic anhydride with an alkaline solution after the reaction is completed, standing for layering and then carrying out washing with clear water for several times. After alcohol-containing wastewater is collected, alcohols are recovered with a recovery tower and are reused. A lower ester layer after layering is heated to recover alcohols at reduced pressure (methanol is recovered by using a supergravity bed and is reused). After activated carbon is added for decoloration, the finished product of DMP is obtained through filter pressing by adopting a plate-and-frame filter press. The preparation method has the beneficial effects that the superfluous alcohol serves as a water-carrying agent, so that the esterification reaction is gradually carried through to the end, the technological process is simplified and the product quality is good; relative to a process of distillation in a rectifying tower, the preparation method has the advantages that the supergravity bed is used to recover methanol in the process, so that the energy consumption is effectively reduced and the process has better environment-friendly significance.

Description

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AI Technical Summary

Benefits of technology

This technology improves upon previous methods by utilizing an extra amount of ethylene glycol (EG) instead of adding more liquid or gasoline during production. By doing away with traditional processes like evaporation from petroleum products, these techniques simplify the overall manufacturing process while also reducing costs associated therewith. Additionally, they can produce high-quality pure EG for use in various applications such as fuel cells without any harmful emissions being released into their environment.

Problems solved by technology

This patented technical problem addressed by this patents relates to producing low-cost diphenic acid esters (DPH) without sacrificially affecting their performance or reducing its effectiveness on certain types of polymer matrices such as those made from polyviny chloride ("PVC").

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