Catalyst for low-temperature gaseous phase synthesis of benzaldehyde and preparation method thereof

Abstract

The invention discloses a catalyst for low-temperature gaseous phase synthesis of benzaldehyde and a preparation method thereof. The molecular formula of the catalyst is M-Ag-HMS, wherein M is alkali metal, alkaline earth metal or rare earth metal element. The preparation method comprises the following steps of: dissolving primary amine RN serving as a template agent into absolute ethanol to obtain primary amine ethanol solution; preparing mixed solution of silver and potassium nitrate, adding the mixed solution into the primary amine ethanol solution, stirring the solution uniformly till a colloidal material is produced, dripping ethyl orthosilicate into the colloidal material with violent stirring, continuously stirring the colloidal material till sediment is generated, and performing crystallization, filtration, washing, drying, roasting, tabletting and screening to obtain the catalyst. The catalyst has the advantages of high catalytic activity, strong selectivity, simple synthesisprocess, stable structure and long life; when the catalyst is filled in a fixed bed reaction kettle to synthesize benzaldehyde by gaseous phase catalytic oxidation of benzyl alcohol, the reaction conditions are mild, the purity of the product is high, and the costs of separation and purification are reduced; and the catalyst is easy for reclamation and regeneration.

Description

technical field

[0001] The invention relates to a catalyst for low-temperature gas phase synthesis of benzaldehyde, which is a composite modified HMS catalyst. The invention also relates to a preparation method of the catalyst. Background technique

[0002] Benzaldehyde is an important fine chemical and organic intermediate, widely used in the fields of pharmaceuticals, dyes, cosmetics and polymer synthesis. Benzaldehyde (carbonyl compound) is a product of alcohol oxidation. It is unstable under oxidation conditions and is often continuously oxidized, especially aldehydes are more likely to be oxidized to carboxylic acids. Therefore, the selective oxidation of alcohols to aldehydes is a very challenging topic, and the development of highly selective and efficient alcohol oxidation methods has attracted increasing attention. Currently, with H 2 o 2 , O 2 Or air as a clean oxidant, the reaction system is mainly liquid-phase homogeneous and heterogeneous oxidation...

Examples

Embodiment 1

[0020] Mix and dissolve 5.00 g of template agent dodecylamine and 41.46 g of absolute ethanol, and stir in a water bath at 30 °C until clarification; add 0.68 g of silver nitrate, 0.809 g of potassium nitrate, and 72 mL of deionized water to the above solution to prepare a mixed solution , continue to stir for a period of time to form a gel; then add 20.88 g of ethyl orthosilicate dropwise at a titration rate of 0.45 mL / min, continue to stir for 24 h, and the reaction temperature is 30 °C; crystallize for 24 h, and the crystallization temperature is 30 °C , filtered, washed, dried, and baked at 550 °C for 6 h to remove the template agent. The catalyst is recorded as: K-Ag-HMS-1.

Embodiment 2

[0022] Mix and dissolve 5.00 g of dodecylamine, 0.68 g of silver nitrate, 0.809 g of potassium nitrate, 41.46 g of absolute ethanol, and 72 mL of deionized water, in a water bath at 30 °C, and magnetically stir until gel appears; then titrate at 0.45 mL / min Add 20.88 g of ethyl orthosilicate dropwise at a high speed, continue to stir for 24 h, the reaction temperature is 30 °C; crystallize for 24 h, the crystallization temperature is 30 °C, filter, wash, dry, and bake at 550 °C for 6 h to remove the template agent. The catalyst is recorded as: K-Ag-HMS-2.

Embodiment 3

[0024] The catalyst obtained in Example 1 was pressed into tablets and sieved, and 40-60 mesh was selected as the catalyst, and benzaldehyde was synthesized by gas-phase catalytic oxidation of benzyl alcohol in a fixed-bed reactor at normal pressure, and the 40-60 mesh catalyst K / Ag-HMS Mix a certain amount of 40-60 mesh quartz sand, put it into the reactor, the catalyst dosage is 0.5 g, N 2 The flow rate is 38 mL / min, O 2 The flow rate was 13 mL / min, the feed rate of benzyl alcohol was 0.10 mL / min, the reaction temperature was 215-220 °C, and the reaction time was 2 h. The gas phase products and unreacted benzyl alcohol were collected in ice-salt bath (-10~-15 ℃), and the collected products were analyzed by FID gas chromatography; the conversion rate of benzyl alcohol was 94.71%, and the selectivity of benzaldehyde was 97.56%.

[0025] The reaction temperature was 320 ℃, the reaction time was 2 h, the conversion of benzyl alcohol was 64.11 %, and the selectivity ...

technical field

[0001] The invention relates to a catalyst for low-temperature gas phase synthesis of benzaldehyde, which is a composite modified HMS catalyst. The invention also relates to a preparation method of the catalyst. Background technique

[0002] Benzaldehyde is an important fine chemical and organic intermediate, widely used in the fields of pharmaceuticals, dyes, cosmetics and polymer synthesis. Benzaldehyde (carbonyl compound) is a product of alcohol oxidation. It is unstable under oxidation conditions and is often continuously oxidized, especially aldehydes are more likely to be oxidized to carboxylic acids. Therefore, the selective oxidation of alcohols to aldehydes is a very challenging topic, and the development of highly selective and efficient alcohol oxidation methods has attracted increasing attention. Currently, with H 2 o 2 , O 2 Or air as a clean oxidant, the reaction system is mainly liquid-phase homogeneous and heterogeneous oxidation...

Examples

Embodiment 1

[0020] Mix and dissolve 5.00 g of template agent dodecylamine and 41.46 g of absolute ethanol, and stir in a water bath at 30 °C until clarification; add 0.68 g of silver nitrate, 0.809 g of potassium nitrate, and 72 mL of deionized water to the above solution to prepare a mixed solution , continue to stir for a period of time to form a gel; then add 20.88 g of ethyl orthosilicate dropwise at a titration rate of 0.45 mL / min, continue to stir for 24 h, and the reaction temperature is 30 °C; crystallize for 24 h, and the crystallization temperature is 30 °C , filtered, washed, dried, and baked at 550 °C for 6 h to remove the template agent. The catalyst is recorded as: K-Ag-HMS-1.

Embodiment 2

[0022] Mix and dissolve 5.00 g of dodecylamine, 0.68 g of silver nitrate, 0.809 g of potassium nitrate, 41.46 g of absolute ethanol, and 72 mL of deionized water, in a water bath at 30 °C, and magnetically stir until gel appears; then titrate at 0.45 mL / min Add 20.88 g of ethyl orthosilicate dropwise at a high speed, continue to stir for 24 h, the reaction temperature is 30 °C; crystallize for 24 h, the crystallization temperature is 30 °C, filter, wash, dry, and bake at 550 °C for 6 h to remove the template agent. The catalyst is recorded as: K-Ag-HMS-2.

Embodiment 3

[0024] The catalyst obtained in Example 1 was pressed into tablets and sieved, and 40-60 mesh was selected as the catalyst, and benzaldehyde was synthesized by gas-phase catalytic oxidation of benzyl alcohol in a fixed-bed reactor at normal pressure, and the 40-60 mesh catalyst K / Ag-HMS Mix a certain amount of 40-60 mesh quartz sand, put it into the reactor, the catalyst dosage is 0.5 g, N 2 The flow rate is 38 mL / min, O 2 The flow rate was 13 mL / min, the feed rate of benzyl alcohol was 0.10 mL / min, the reaction temperature was 215-220 °C, and the reaction time was 2 h. The gas phase products and unreacted benzyl alcohol were collected in ice-salt bath (-10~-15 ℃), and the collected products were analyzed by FID gas chromatography; the conversion rate of benzyl alcohol was 94.71%, and the selectivity of benzaldehyde was 97.56%.

[0025] The reaction temperature was 320 ℃, the reaction time was 2 h, the conversion of benzyl alcohol was 64.11 %, and the selectivity ...