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
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Embodiment 1
[0024] In the present embodiment, the method for preparing benzaldehyde by oxidation of toluene is as follows, in a 500ml reactor, add solvent benzyl benzoate 240g, toluene 60g and catalyst cobalt benzoate 3.0g, start stirring, feed air so that the absolute pressure in the reactor is 0.3MPa, then turn on the heating to heat the reaction liquid to 180-185°C, the air flow rate is 0.4L / min, and the absolute pressure of the reactor is kept at 0.35MPa. Separation, toluene returns to the reactor, and water is treated as waste liquid. React for 6 hours, turn off the air to cool. Quantitative analysis by gas chromatography showed that the reaction liquid 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 78.3%. After the reaction solution separates toluene, benzaldehyde, benzyl alcohol and benzoic acid by distillation, the mother liquor containing ben...
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, start stirring, react under normal pressure, feed air at a flow rate of 0.2L / min, and heat until the reaction The temperature is 225-230°C, and the mixed solution of benzyl benzoate, catalyst and toluene is added at a flow rate of 30g / h. The content of toluene in the mixed solution is 30%, and the reaction solution is continuously released to keep the liquid level in the reactor at a constant temperature. Beginning height, the reaction liquid distillation that emits is separated out benzaldehyde, benzyl alcohol and benzoic acid, remaining benzyl benzoate and catalyst mother liquor are purified and then add 30% raw material toluene to mix and return to with the flow velocity of 30g / h In the reactor; Stop adding the mixed solution of fresh benzyl benzoate, catalyst and toluene simultaneously. The gas phase on the reaction liquid contains tolue...
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 an air flow rate of 0.2L / min, be heated to reaction temperature and be 220-225 ℃, add the mixed solution of benzyl benzoate, catalyzer and toluene with the flow rate of 30g / h, toluene content is 30% in the mixed solution, constantly emit reaction solution to make the liquid in the reactor The position is kept at the initial height, and the reaction liquid distilled to separate benzaldehyde, benzyl alcohol and benzoic acid, and the remaining benzyl benzoate and catalyst mother liquor are purified and added with 30% raw material toluene to mix and with a flow rate of 30g / h Return in the reactor; Stop adding the mixed solution of fresh benzyl benzoate, catalyst and toluene simultaneously. The gas phase on the reaction liquid contains toluene, benzaldehyde and water, a...
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