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Technology for preparing salicylic acid through micro-channel continuous-flow reactor

A technology of reactor and microchannel, which is applied in carboxylate preparation, carboxylate preparation, organic chemistry, etc., can solve the problems of low production efficiency and raw material conversion rate, affecting reaction selectivity, and prone to side reactions, etc., to achieve Improve production efficiency, improve stability, and facilitate the effect of mass and heat transfer

Inactive Publication Date: 2019-07-23
SOUTHEAST UNIV
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0003] The core step of the preparation method is the carboxylation reaction of sodium phenate and carbon dioxide. In the traditional process, this process is reacted in a gas-solid form. The reaction is difficult to complete, and the production efficiency and raw material conversion rate are low. Patent 00123036.0 (solvent method) A new process for salicylic acid) proposes to use octanol as a solvent for sodium phenate to improve the traditional gas-solid reaction into a gas-liquid reaction, thereby effectively improving production efficiency and raw material conversion rate. However, the reaction is still a two-phase interface reaction , the reaction efficiency of the traditional process method is low, and at the same time, because the thermal effect generated by the reaction cannot be removed in time, side reactions are prone to occur, which affects the selectivity of the reaction

Method used

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  • Technology for preparing salicylic acid through micro-channel continuous-flow reactor

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Experimental program
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Effect test

Embodiment 1

[0021] The n-hexyl alcohol solution of sodium phenate and carbon dioxide are pumped into the preheating module of microchannel continuous flow reactor respectively, after preheating finishes, enter mixing module and reaction module and react, the mol ratio of the sodium phenate entering reaction module and carbon dioxide is 1: 3. The temperature of the preheating module, the mixing module and the reaction module is set to 160°C, the pressure of the reaction module is controlled by the back pressure valve control system at the outlet of the reaction module to 1.0MPa, and the retention time of the reaction is 300s. After the reaction is completed, the reactant After the cooling module, it enters the separation module to complete the gas-liquid separation, the carbon dioxide in the gas phase is recovered and recycled, and the liquid phase enters the sodium salicylate storage tank.

[0022] Extract the sodium salicylate in the sodium salicylate solution with water. After the extrac...

Embodiment 2

[0024] The n-octanol solution of sodium phenate and carbon dioxide are pumped into the preheating module of microchannel continuous flow reactor respectively, after preheating finishes, enter mixing module and reaction module and react, the mol ratio of the sodium phenate entering reaction module and carbon dioxide is 1: 1. The temperature of the preheating module, the mixing module and the reaction module is set to 110°C, the pressure of the reaction module is controlled by the back pressure valve control system at the outlet of the reaction module to 2.0MPa, and the retention time of the reaction is 900s. After the reaction is completed, the reactant After the cooling module, it enters the separation module to complete the gas-liquid separation, the carbon dioxide in the gas phase is recovered and recycled, and the liquid phase enters the sodium salicylate storage tank.

[0025] The sodium salicylate in the sodium salicylate solution is extracted with water. After the extract...

Embodiment 3

[0027] The n-hexyl alcohol solution of sodium phenate and carbon dioxide are pumped into the preheating module of microchannel continuous flow reactor respectively, after preheating finishes, enter mixing module and reaction module and react, the mol ratio of the sodium phenate entering reaction module and carbon dioxide is 1: 10. The temperature of the preheating module, the mixing module and the reaction module is set to 200°C, the pressure of the reaction module is controlled by the back pressure valve control system at the outlet of the reaction module to 0.1MPa, and the retention time of the reaction is 100s. After the reaction is completed, the reactant After the cooling module, it enters the separation module to complete the gas-liquid separation, the carbon dioxide in the gas phase is recovered and recycled, and the liquid phase enters the sodium salicylate storage tank.

[0028] Extract the sodium salicylate in the sodium salicylate solution with water. After the extra...

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Abstract

The invention discloses a technology for preparing salicylic acid through a micro-channel continuous-flow reactor. The technology comprises the following steps: (1) mixing a preheated sodium phenoxidesolution and preheated carbon dioxide in the micro-channel continuous-flow reactor, reacting, cooling and discharging after reaction, performing gas-liquid separation on material liquid and collecting a liquid solution; (2) utilizing water to extract the liquid solution prepared in the step (1) and acidifying an obtained water solution to prepare a salicylic acid crude product. The preparation technology disclosed by the invention can greatly improve the gas-liquid contact area in a reaction process, and the production efficiency is improved; meanwhile, the fine pipe diameter and the large specific surface area of the micro-channel reactor are favorable for mass and heat transfer of a reaction system, and occurrence of side reaction in the reaction process is reduced; in addition, the continuous reaction characteristic can effectively improve stability of product quality; by means of the reaction device, the sodium phenoxide conversion rate can reach 93% or above, and the salicylic acid yield can reach 91% or above; thus, the preparation technology is very suitable for industrial production.

Description

technical field [0001] The invention relates to a process for preparing salicylic acid using a microchannel continuous flow reactor, belonging to the technical field of salicylic acid preparation. Background technique [0002] Salicylic acid is an important synthetic intermediate, which is widely used in medicine, fuel, chemical preparation and other fields. The synthesis of salicylic acid is generally carried out through the Kolbe-Schmitt reaction, that is, the electrophilic substitution reaction of carbon dioxide and organic phenolic compounds, and the reaction of introducing carboxyl groups on the aromatic ring. According to the difference in pressure when sodium phenate is converted into salicylic acid, the preparation method of salicylic acid is divided into phenol normal pressure method and phenol medium pressure method, wherein, the latter is the method commonly used in the industry at present, and this method first uses phenol as raw material , react with sodium hyd...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/02C07C65/10
CPCC07C51/02C07C51/41C07C65/10
Inventor 焦真石闻卿李乃旭周建成
Owner SOUTHEAST UNIV
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