Method and device of continuously synthesizing tetramethyl ammonium carbonate by multi-reactors in series

Abstract

The invention discloses a method and a device of continuously synthesizing tetramethyl ammonium carbonate by multi-reactors in series. Liquid-phase reaction materials in each reactor are connected in series through a pipeline. Gas-phase reaction materials are connected in parallel to keep the pressure between reactors balanced. The reaction materials flow into a next stage reactor from a previousstage reactor through the difference of liquid level in the reactors. The two stage reactors have a difference of liquid level of 0.5-1.0 m. The tetramethyl ammonium carbonate is prepared by continuously adding raw materials including dimethyl carbonate, trimethylamine and solvent methanol to a first stage tank reactor in a mole ratio of 1:0.8:3-1:1.5:8, leading a reaction mixture to continuouslyflow out from the last stage tank reactor, recycling a reaction solvent and an unconverted reactant by flash evaporation, then re-adding to the first stage tank reactor for recycling, and finally removing the solvent and the unconverted reactant. The operation pressure of the invention is the lowest, the reaction is stable, and continuous operation and automatic control are realized. Simultaneously, the reaction materials are heated to a reaction temperature by reaction heat, so the energy is saved and the production cost is reduced.

Description

technical field [0001] The invention relates to a method and a device for preparing tetramethylammonium carbonate salt in series with continuous multiple kettles. Background technique [0002] Tetramethylamine hydroxide, also known as tetramethylamine hydroxide (TMAH), is the strongest organic base, which decomposes into methanol and trimethylamine at 130°C. Because TMAH has strong alkalinity, it does not remain after heating and decomposition. Any substance, especially does not leave a conductive ionic substance, so it is widely used as a developer in the manufacturing process of liquid crystal displays, LEDs and semiconductor chips. It is also widely used in other industrial fields, for example, it can be used as a catalyst in the synthesis of organic silicon series products, and can be used in polyester polymerization, textile, plastic products, leather and other industries. [0003] Tetramethylammonium hydroxide is prepared in two steps, the first step is the synthesis ...

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Problems solved by technology

[0013] It can be seen from the above patents that both the batch reactor and the tubular reactor have their disadvantages. The batch reaction has low production efficiency and complicated operation. The reaction between trimethylamine and dimethyl carbonate is a strong exothermic process. Reaction, with the progress of the reaction, the concentration of the reactant changes constantly, and the reaction rate also changes accordingly, so the heat released by the reaction system is also changing constantly. In order to ensure that the temperature of the reaction system remains unchanged, it is necessary to continuously adjust the amount of cooling water. This in turn causes the reaction temperature to fluctuate in a wide range, which brings a lot of trouble to the actual operation. Due to the fluctuation of the reaction conditions, it also affects the stability of the product quality and yield in the batch reaction process.

[0014] For the tubular reactor, since the boiling points of the raw material trimethylamine, dimethyl carbonate and the reaction solvent differ greatly, at the reaction temperature, a gas-liquid two-phase flow will be formed in the tubular reactor, in order to make trimethylamine and dimethyl carbonate The two raw materials of the ester are fully mixed, and a static mixer and a Raschig ring ceramic filler must be installed in the tubular reactor, which increases the complexity of the reactor and makes the design of the reactor more difficult. At the same time, the Raschig ring is filled Ceramic fillers also increase the probability of introducing impurity ions into synthetic products, which is not conducive to achieving qualified electronic grade products TMAH

At the same time, the synthetic reaction of trimethylamine and dimethyl carbonate is a strong exothermic reaction, which is very sensitive to the reaction temperature. In the inlet section of the tubular reactor, the raw material concentration is high, the reaction speed is fast, and the heat released is large. If the reaction temperature If it is not removed in time, the reaction temperature will be further increased, the reaction speed will be further increased, and finally the temperature of the reaction system cannot be controlled. Therefore, the removal of reaction heat is the key to the smooth progress of the reaction. There is also a problem of how to control the reaction temperature in the adiabatic tubular reactor. ; For an isothermal tubular reactor, the concentration of the reactants in the axial direction of the reactor decreases continuously, the reaction rate also decreases correspondingly, the heat released is also decreasing, and it is difficult to remove the heat of reaction smoothly

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