Method for coproducing methylbenzoic acid, methyl benzonitrie and phthalonitrile

Abstract

The invention discloses a method for coproducing methylbenzoic acid, methyl benzonitrie and phthalonitrile. The method comprises the following steps: (1) continuously introducing xylol, a catalyst andoxygen-containing gas into an oxidation reactor and reacting to obtain an oxidation reaction solution; (2) conveying the oxidation reaction solution into a primary evaporation tower and carrying outrectification separation; when the content of methylbenzyl alcohol in a tower kettle solution of the primary evaporation tower reaches 0.01 to 0.15 weight percent, stopping rectification, so as to obtain a low-boiling-point component and the tower kettle solution of the primary evaporation tower; (3) conveying the tower kettle solution of the primary evaporation tower into a rectification tower and carrying out rectification; when the content of the methylbenzoic acid in a tower kettle solution of the rectification tower reaches 30 to 90 weight percent, stopping rectification, so as to obtaina methylbenzoic acid product and the tower kettle solution of the rectification tower; (4) mixing the tower kettle solution of the rectification tower and ammonia to obtain a nitrile-containing reaction solution; (5) carrying out rectification separation on the nitrile-containing reaction solution to obtain methyl benzonitrie and phthalonitrile products. The method disclosed by the invention has the advantages of simple technology, few equipment investment, greenness and environment protection and good comprehensive economic benefits.

Description

technical field

[0001] The invention relates to the technical field of fine chemicals, in particular to a method for co-producing methylbenzoic acid, methylbenzonitrile and phthalonitrile. Background technique

[0002] Tolunitrile includes m-methylbenzonitrile, p-methylbenzonitrile and o-methylbenzonitrile, all of which are widely used in medicine, pesticides, photosensitive materials and dye intermediates. The existing production of methyl benzonitrile mainly uses high-purity methyl benzoic acid as a raw material, and after preparing methyl benzonitrile through amination and dehydration reactions, the product is refined and purified by rectification. Due to the high boiling point of the product, more rectification residues will be produced in the rectification process, resulting in a large amount of solid waste residue in the rectification column and low product yield. Generally, the molar yield based on toluic acid is not more than 85%. Another production method of methy...

Examples

Embodiment 1

[0101] The catalyst that dissolves in the fresh p-xylene that adds in the oxidation reactor is cobalt naphthenate, metal phthalocyanine (R with general formula (IV) structure 1 =CH 3 CH 2 , R 2 =H, M=Mn), the metalloporphyrin (R 1 = R 2 = H, R 3 =CH 3 , M=Cu) mixture, the total concentration is 75ppm, the reaction temperature is 180°C, the reaction pressure is 2MPa, the oxygen-containing gas is the oxygen-enriched air of 24% oxygen concentration, the residence time of the reactants in the oxidation reactor is adjusted to make the The conversion rate of xylene was 42%, and the oxidation reaction solution was obtained. At this time, the mass percentage of each component in the reaction solution obtained by HPLC analysis is listed in Table 1. In the initial distillation tower, the boiling point in the oxidation reaction liquid is lower than all components of p-methylbenzyl alcohol for rectification separation, and when the p-methylbenzyl alcohol content reaches 0.06wt% in t...

Embodiment 2

[0104] The catalyst dissolved in fresh p-xylene fed to the oxidation reactor was MnO 2 And cobalt acetylacetonate, total concentration is 350ppm, and reaction temperature is 150 ℃, and reaction pressure is 1MPa, oxygen-containing gas concentration 21%, operation process is identical with embodiment 1, and difference is that the conversion rate control of p-xylene is 50% , the mass percent content of p-methylbenzyl alcohol in the initial distillation tower still liquid is controlled to be 0.07%. The mass percent composition of each component that HPLC analysis obtains in the reaction solution is listed in Table 1, and the quality, composition and the content of methylbenzoic acid in the first distillation column tower bottom liquid that obtains are listed in the table 2.

[0105] Add the liquid from the above-mentioned initial distillation tower to the rectification tower for rectification, and obtain 889.4 g of p-toluic acid product with a purity of 99.0% at the top of the to...

Embodiment 3

[0107] Add the catalyst dissolved in the fresh p-xylene in the oxidation reactor to be N-hydroxyphthalimide, cobalt isooctanoate, metal phthalocyanine (R with general formula (IV) structure 1 =OH,R 2 =H, M=Ru) and metalloporphyrins (R 1 = R 3 = H, R 2 =OH,M 1 = M 2 =Mn) mixture, the total concentration is 10000ppm, the reaction temperature is 116 ° C, the reaction pressure is 0.2MPa, the oxygen-containing gas is pure oxygen, the operation process is the same as in Example 1, and the difference is that the conversion rate of p-xylene is controlled as 60%, and the mass percent content of p-methylbenzyl alcohol in the initial distillation tower bottom liquid is controlled to be 0.10%. The mass percent composition of each component that HPLC analysis obtains in the reaction solution is listed in Table 1, and the quality, composition and the content of methylbenzoic acid in the first distillation column tower bottom liquid that obtains are listed in the table 2.

[0108] Add...

technical field

[0001] The invention relates to the technical field of fine chemicals, in particular to a method for co-producing methylbenzoic acid, methylbenzonitrile and phthalonitrile. Background technique

[0002] Tolunitrile includes m-methylbenzonitrile, p-methylbenzonitrile and o-methylbenzonitrile, all of which are widely used in medicine, pesticides, photosensitive materials and dye intermediates. The existing production of methyl benzonitrile mainly uses high-purity methyl benzoic acid as a raw material, and after preparing methyl benzonitrile through amination and dehydration reactions, the product is refined and purified by rectification. Due to the high boiling point of the product, more rectification residues will be produced in the rectification process, resulting in a large amount of solid waste residue in the rectification column and low product yield. Generally, the molar yield based on toluic acid is not more than 85%. Another production method of methy...

Examples

Embodiment 1

[0101] The catalyst that dissolves in the fresh p-xylene that adds in the oxidation reactor is cobalt naphthenate, metal phthalocyanine (R with general formula (IV) structure 1 =CH 3 CH 2 , R 2 =H, M=Mn), the metalloporphyrin (R 1 = R 2 = H, R 3 =CH 3 , M=Cu) mixture, the total concentration is 75ppm, the reaction temperature is 180°C, the reaction pressure is 2MPa, the oxygen-containing gas is the oxygen-enriched air of 24% oxygen concentration, the residence time of the reactants in the oxidation reactor is adjusted to make the The conversion rate of xylene was 42%, and the oxidation reaction solution was obtained. At this time, the mass percentage of each component in the reaction solution obtained by HPLC analysis is listed in Table 1. In the initial distillation tower, the boiling point in the oxidation reaction liquid is lower than all components of p-methylbenzyl alcohol for rectification separation, and when the p-methylbenzyl alcohol content reaches 0.06wt% in t...

Embodiment 2

[0104] The catalyst dissolved in fresh p-xylene fed to the oxidation reactor was MnO 2 And cobalt acetylacetonate, total concentration is 350ppm, and reaction temperature is 150 ℃, and reaction pressure is 1MPa, oxygen-containing gas concentration 21%, operation process is identical with embodiment 1, and difference is that the conversion rate control of p-xylene is 50% , the mass percent content of p-methylbenzyl alcohol in the initial distillation tower still liquid is controlled to be 0.07%. The mass percent composition of each component that HPLC analysis obtains in the reaction solution is listed in Table 1, and the quality, composition and the content of methylbenzoic acid in the first distillation column tower bottom liquid that obtains are listed in the table 2.

[0105] Add the liquid from the above-mentioned initial distillation tower to the rectification tower for rectification, and obtain 889.4 g of p-toluic acid product with a purity of 99.0% at the top of the to...

Embodiment 3

[0107] Add the catalyst dissolved in the fresh p-xylene in the oxidation reactor to be N-hydroxyphthalimide, cobalt isooctanoate, metal phthalocyanine (R with general formula (IV) structure 1 =OH,R 2 =H, M=Ru) and metalloporphyrins (R 1 = R 3 = H, R 2 =OH,M 1 = M 2 =Mn) mixture, the total concentration is 10000ppm, the reaction temperature is 116 ° C, the reaction pressure is 0.2MPa, the oxygen-containing gas is pure oxygen, the operation process is the same as in Example 1, and the difference is that the conversion rate of p-xylene is controlled as 60%, and the mass percent content of p-methylbenzyl alcohol in the initial distillation tower bottom liquid is controlled to be 0.10%. The mass percent composition of each component that HPLC analysis obtains in the reaction solution is listed in Table 1, and the quality, composition and the content of methylbenzoic acid in the first distillation column tower bottom liquid that obtains are listed in the table 2.

[0108] Add...

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