Clean recovery method of toluene oxidation catalyst

Abstract

The invention discloses a recovery method for toluene oxidation production of benzaldehyde or a benzoic acid catalyst. The method is mainly characterized by comprising the following steps of: oxidizing toluene to produce benzaldehyde, benzyl alcohol and benzoic acid, and generating water in toluene oxidation reaction of taking cobalt, manganese and bromine as a catalytic system; firstly, extracting reactant toluene, and products benzaldehyde, benzoic acid and benzyl alcohol into cyclohexane by cyclohexane after the reaction is finished; separating an organic phase from a water phase containing the catalyst; separating the organic phase by rectification; firstly, separating all cyclohexane to feed to an extraction system; then separating acetic acid and toluene to feed to a reaction system; finally separating the product benzaldehyde and benzyl alcohol from benzoic acid; and feeding the catalyst containing a little of benzoic acid to the reaction system for directly carrying out next batch of toluene oxidation reaction after carrying out simple distillation to remove moisture by a water phase. The result shows that the recovered catalyst still has a good catalytic effect on toluene oxidation; and main product benzaldehyde is less in loss and high in yield in the separating process.

Description

Technical field: [0001] The invention relates to a method for preparing benzaldehyde and benzoic acid by oxidizing toluene. Background technique [0002] Traditional benzaldehyde and benzoic acid are prepared by chlorination and hydrolysis of toluene. In this method, toluene is first chlorinated with side methyl groups under light conditions to mainly generate a mixture of benzyl chloride, and then benzyl chloride is reacted in acidic or alkaline Under the conditions of hydrolysis and rectification, benzoic acid and benzaldehyde were obtained. The disadvantage of this method is that the reaction process is long and complicated, and the liquid Cl 2 It is easy to have safety hazards, it is difficult to remove Cl in the product, and it is difficult to apply the product in food additives. Benzaldehyde and benzoic acid prepared by the direct oxidation of toluene not only meet the requirements of food standards, but also are environmentally friendly. The main products of cobalt...

AI Technical Summary

Problems solved by technology

The present invention first uses cyclohexane extraction to separate the reaction product from the catalyst, effectively solving the problem that benzaldehyde is easily oxidized due to coexistence with the catalyst in the separation process. Formic acid can promote the generation of peroxy radicals in the oxidation of toluene, can play the role of initiator, and is beneficial to the oxidation of toluene, so it is not necessary to separate it from the catalyst, which not only reduces the steps of catalyst recovery, but also makes the recovered catalyst effective. better catalytic effect

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