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Method for preparing benzaldehyde by oxidizing toluene

A technology for benzaldehyde and toluene, applied in the field of toluene oxidation to prepare benzaldehyde, can solve the problems of small market of benzyl alcohol acetate, low conversion rate of single-stage reactor, uneconomical industrial production, etc. Separation, less waste liquid and less residue

Inactive Publication Date: 2010-07-28
申广照
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Problems solved by technology

In the Chinese patent No. CN101607867 in 2009, the method of connecting multi-stage oxidation reactor and gas-liquid separator in series was adopted, the conversion rate of toluene reached over 95%, and the total selectivity of benzaldehyde and benzyl alcohol reached over 50%. , but the conversion rate of the single-stage reactor is low and the energy consumption is high
In the above-mentioned method for preparing benzaldehyde by direct liquid-phase oxidation of toluene, all can not ensure that benzaldehyde has high selectivity while satisfying the high conversion rate of toluene; adopt organic acid to improve the situation, but increase the separation process and the introduction of other impurities
[0007] In 2004, the Chinese patent No. CN1528726 disclosed a method for preparing benzaldehyde by liquid-phase oxidation of aromatic hydrocarbon side chains in an acidic or neutral ionic liquid and acetic acid mixed solvent, at 115-120°C Oxidation of toluene, when the conversion rate of toluene was 42%, the selectivity of benzaldehyde was 48%, and the selectivity of benzyl alcohol acetate was 58%. This method uses a large amount of expensive ionic liquid and acetic acid solvent, which greatly increases the production cost , and the separation of products is relatively difficult, and the market for the benzyl alcohol acetate produced at the same time is not large, and further processing is required to recycle benzyl alcohol and acetic acid, and industrial production is uneconomical
[0008] In summary, there is not yet a method for the production of benzaldehyde that is simple in reaction, energy-saving and environmentally friendly, and product and solvent are easy to separate and recycle, and the conversion rate of toluene in the reaction and the selectivity of benzaldehyde are higher at the same time

Method used

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  • Method for preparing benzaldehyde by oxidizing toluene
  • Method for preparing benzaldehyde by oxidizing toluene
  • Method for preparing benzaldehyde by oxidizing toluene

Examples

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Embodiment 1

[0024] The method for preparing benzaldehyde by oxidation of toluene in this example is as follows. In a 500ml reactor, add 240g of solvent benzyl benzoate, 60g of toluene and 3.0g of catalyst cobalt benzoate, turn on the stirring, and let air into the reactor so that the absolute pressure in the reactor is 0.3MPa, then turn on the heating to heat the reaction liquid to 180-185℃, the air flow rate is 0.4L / min, and the absolute pressure of the reactor is maintained at 0.35MPa. The water produced by the reaction azeotropes with toluene, and is condensed with oil and water After separation, toluene is returned to the reactor, and water is treated as waste liquid. After reacting for 6 hours, the air cooling was turned off. Quantitative analysis by gas chromatography showed that the reaction solution contained 28.6 g of toluene, 28.3 g of benzaldehyde, 3.2 g of benzyl alcohol and 4.2 g of benzoic acid. The conversion rate of toluene was 52.3%, and the selectivity of benzaldehyde was...

Embodiment 2

[0026] Add 280g of solvent benzyl benzoate, 20g of toluene, 3.0g of cobalt benzoate, and 1.0g of manganese benzoate into a 500ml reactor, turn on the stirring, and react under normal pressure. The flow of air is 0.2L / min, and the reaction is heated. The temperature is 225-230℃, and the mixed liquid of benzyl benzoate, catalyst and toluene is added at a flow rate of 30g / h. The content of toluene in the mixed liquid is 30%. The reaction liquid is continuously released to keep the liquid level in the reactor at a high level. The reaction liquid is distilled to separate the benzaldehyde, benzyl alcohol and benzoic acid. The remaining benzyl benzoate and the catalyst mother liquor are purified and then mixed with 30% of the raw material toluene, and the flow rate is 30g / h. In the reactor; stop adding fresh benzyl benzoate, catalyst and toluene mixture at the same time. The gas phase on the reaction liquid contains toluene, benzaldehyde and water. The toluene, benzaldehyde and water ...

Embodiment 3

[0028] Add 500g of solvent benzyl benzoate, 40g of toluene, 6.0g of cobalt benzoate, 1.0g of manganese benzoate, and 0.5g of nickel benzoate into an 800ml bubble column reactor, and react under normal pressure with a flow of air of 0.2L / min, heating to a reaction temperature of 220-225°C, adding a mixture of benzyl benzoate, catalyst and toluene at a flow rate of 30 g / h. The toluene content of the mixture is 30%. The reaction solution is continuously released to make the reactor liquid Keep the position at the initial height, distill the released reaction liquid to separate benzaldehyde, benzyl alcohol and benzoic acid, and the remaining benzyl benzoate and the catalyst mother liquor are purified and mixed with 30% raw material toluene and mixed with a flow rate of 30g / h Return to the reactor; stop adding fresh benzyl benzoate, catalyst and toluene mixture. The gaseous phase on the reaction liquid contains toluene, benzaldehyde and water. The gaseous phase containing toluene, ...

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Abstract

The invention relates to a method for preparing benzaldehyde by oxidizing toluene. Currently, no method for producing the benzaldehyde has simple reactions as well as high toluene percent conversion and benzaldehyde selectivity. The raw materials comprise 1-59% of toluene, 0.005-5% of master catalyst, oxygen source and 40-98% of benzyl benzoate, wherein the mol ratio of oxygen molecules in the oxygen source to toluene is (0.3-3):1, and the master catalyst is one or more than two of cobalt ions, manganese ions, vanadium ions and nickel ions. The method comprises the following steps: mixing the toluene, master catalyst and benzyl benzoate in a reactor; at the temperature of 140-300 DEG C and under the absolute pressure of 0.05-1.0 MPa, introducing the oxygen source into the mixed liquor to react for more than 2 hours; and refining the mixed liquor to obtain the benzaldehyde. The toluene percent conversion is higher than 30%, and the benzaldehyde selectivity is higher than 70%. The invention has the advantages of simple reaction, energy conservation, environmental protection, easy separation of products and solvent, and high toluene percent conversion and benzaldehyde selectivity.

Description

Technical field [0001] The invention relates to a method for preparing benzaldehyde, in particular to a method for preparing benzaldehyde by oxidation of toluene. Background technique [0002] Benzaldehyde is an important fine chemical product, which is widely used in industries such as medicine, dyes, perfumes, pesticides and materials. The disclosed production methods for preparing benzaldehyde mainly include the following three methods: toluene chlorination hydrolysis method, benzoic acid (ester) reduction method, and toluene direct oxidation method. The toluene direct oxidation method includes gas phase method and liquid phase method. [0003] The benzaldehyde produced by the traditional toluene chlorination hydrolysis method inevitably contains chlorine, and the benzaldehyde used in the pharmaceutical and perfume industries cannot contain chlorine. Therefore, the benzaldehyde produced by the toluene chlorination hydrolysis method is The scope of application is limited. For ex...

Claims

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Application Information

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IPC IPC(8): C07C47/54C07C45/36
Inventor 申广照文维
Owner 申广照
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