CN103586066B - The method of benzaldehyde prepared by bimetallic-modified SBA-15 catalyst low-temperature gaseous phase selective catalytic oxidation phenmethylol - Google Patents

Abstract

The method of benzaldehyde prepared by bimetallic-modified SBA-15 catalyst low-temperature gaseous phase selective catalytic oxidation phenmethylol, and it relates to a kind of method that benzaldehyde prepared by phenmethylol.The present invention will solve the existing catalyst preparing corresponding aldehydes or ketones for gas phase selective catalytic oxidation alcohol can not take into account low temperature, high selectivity, high activity, preferably temperature tolerance, the problem in longer service life.Method: bimetallic-modified SBA-15 catalyst mix quartz sand is loaded in atmospheric fixed bed reactor, utilizing charge pump to be squeezed in the preheating furnace of 220 DEG C by liquid benzene methyl alcohol makes liquid benzene methyl alcohol vaporize completely, obtain the phenmethylol after vaporizing, by phenmethylol, O after vaporization ₂and N ₂be passed in atmospheric fixed bed reactor, be react 2h under the condition of 240 DEG C in temperature simultaneously, is that gas-phase product and unreacted phenmethylol are collected in-10 DEG C ~-15 DEG C cryosel baths in temperature.The present invention is mainly used in catalytic oxidation phenmethylol and prepares benzaldehyde.

Description

Method for preparing benzaldehyde by selective catalytic oxidation of benzyl alcohol in low temperature gas phase with double metal modified SBA-15 catalyst

technical field

The invention relates to a method for preparing benzaldehyde from benzyl alcohol.

Background technique

Pure silicon SBA-15 mesoporous molecular sieve has a long-range ordered one-dimensional pore structure, and the mesopore size can be adjusted in the range of 4.6nm to 30nm. Silanol, easy to modify. At the same time, using the confinement effect of its regular nanospace to prepare nano active phases is one of the effective methods for preparing functional nanomaterials, so it is widely used in the catalysis and adsorption industries.

Due to the interaction between metals and active components and supports, bimetallic modified catalysts often produce some effects better than those of single metals.

In recent years, bimetallic modified supported catalysts doped with Cu as the second metal have shown excellent catalytic performance in many reactions.

Au-Cu alloy nanoparticles prepared by Li (Applied Catalysis A: General, 2012, 433–434, 146–151) using SiO ₂ as a carrier were used in the liquid-phase selective oxidation of alcohol with O ₂ as oxidant. The study found that the synergistic effect between metals makes the catalyst have good catalytic activity and selectivity for the selective oxidation of various alcohols. The representative catalyst Au ₅ Cu ₁ /SiO ₂ was used for the selectivity of benzyl alcohol When producing benzaldehyde by oxidation, the conversion rate of benzyl alcohol is 97%, and the selectivity reaches 99%.

Xu et al. (Chinese Journal of Catalysis, 2013, 34:341–350) used Cu as the second metal to prepare Cu/VO _x -TiO ₂ composite catalysts with different amounts of Cu doping, and used them in the liquid-phase direct hydroxylation of benzene to prepare In the reaction of phenol, it was found that the doping of Cu effectively promoted the dispersion of VO _x species on the carrier TiO ₂ and the reduction of VO _x species, and improved the thermal stability of the catalyst; the Cu content of 0.75% Cu (0.75 )/VO _x -TiO2 catalyst has high activity, and the yield and selectivity of phenol reach 25.6% and 92%, respectively.

Habimana et al. (Journal of Natural Gas Chemistry, 2009, 18:392–398) prepared a 12.5% Ni/Cu/SBA-15 catalyst with a Ni content of 12.5% and a Cu content of 1-10% by impregnation method and used it for the methane fraction In the reaction of oxidation to synthesis gas, it was found that the interaction between Cu and Ni species and between the active component and the support significantly improved the redox performance of the catalyst while ensuring high catalytic activity; using 12.5% Ni /2.5%Cu/SBA-15 at a reaction temperature of 850 °C, the conversion of _CH4 reached 97.9%, and the selectivity to CO and _H2 reached 98.0% and 96.0%, respectively.

Zheng et al. (Journal of Molecular Catalysis A: Chemical, 2012, 357:106–111) prepared bimetallic modified Ag ₉₅ -Cu ₅ /BaCO ₃ catalysts for propene with molecular oxygen as oxidant by a surfant-protected colloidal method In the reaction of epoxidation to prepare propylene oxide, the study found that the synergistic effect between doping a small amount of Cu and Ag effectively inhibited the agglomeration of Ag particles, and significantly improved the catalytic performance of the catalyst, and the conversion of propylene was 3.6%, the selectivity of propylene oxide reaches a maximum value of 55.1%.

The oxidation of alcohols to aldehydes and ketones plays an extremely important role in organic synthesis and is widely used in the synthesis of fine chemicals and organic intermediates.

Benzaldehyde is the simplest aromatic aldehyde, commonly known as bitter almond oil. It is an important organic chemical raw material, mainly used for the production of mandelic acid, lauric aldehyde, benzyl benzoate, and also an important intermediate in the dye, spice and pharmaceutical (ephedrine) industries.

In recent years, molecular oxygen is used as oxidant, solid catalyst is used, and fixed bed reactor is used to selectively catalyze the oxidation of benzyl alcohol to form benzaldehyde in gas-solid phase. Since the reaction process has no solvent, less by-products and easy separation of products, the comparison of catalyst reprocessing It is simple and easy to operate, and the continuous reaction is easy to industrialized production, and the reaction process is green and environmentally friendly and is favored.

Temperature is an important factor affecting the gas-phase selective catalytic oxidation of benzyl alcohol to prepare benzaldehyde. An increase in temperature will lead to the peroxidation of the target product benzaldehyde to generate benzoic acid, which will reduce the selectivity of the target product and increase the by-products. If it is increased, hidden dangers will increase, which is not conducive to energy conservation, environmental protection and safe production, and does not conform to the sustainable development strategy. In recent years, low-temperature gas-phase selective catalytic oxidation of benzyl alcohol to generate benzaldehyde, with low reaction temperature, is not only conducive to improving the selectivity of the target product and the life of the active site, but also energy saving and environmental protection, which has attracted more and more attention.

Rossi et al. (Chemical Communications, 2003, 378-379) used HAuCl ₄ aqueous solution as precursor to prepare Au/SiO ₂ catalyst by impregnation method. When the gold loading is 1%, the selectivity of benzaldehyde is about 99.5% when the reaction temperature is 250°C-280°C, and the conversion rate of benzyl alcohol is only controlled at 50%-75%. The lower conversion rate provides a direction for further research by scientific researchers.

Cristin et al. (Journal of Catalysis, 2008, 260:384-386) conducted a more in-depth study on the experiment, using the mixed HAuCl ₄ and CuCl ₂ aqueous solution as the precursor, and prepared Au-Cu bimetallic SiO ₂ by impregnation method The catalyst has a total loading of gold and copper of 1%. When n(Au)/n(Cu)=4, when the reaction temperature is 313° C., the conversion rate of benzyl alcohol is 98%, and the selectivity of benzaldehyde reaches more than 99%. However, the reaction temperature is much higher than the vaporization temperature (205.7°C) of benzyl alcohol, so it does not meet the green production requirements of energy saving and emission reduction.

Zhao et al. (Chemical Communications, 2011, 47:9642-9644) prepared Au/Ni-fiber catalysts by loading Au particles on Ni-fiber carriers by electrodeposition. When the reaction temperature was 280°C, when the gold loading was 4%, the conversion rate of benzyl alcohol reaches 99%, and the selectivity of benzaldehyde is as high as 98%. Although the reaction temperature of the catalyst is reduced, the large loading of Au leads to a significant increase in production cost.

Galen D.Stucky et al. (J.Am.Chem.Soc.2009,131:15568-15569) reported the application of mesoporous K-Cu-TiO ₂ catalyst in gas-phase catalytic oxidation of benzyl alcohol to benzaldehyde. The author prepared the catalyst by means of impregnation. At a temperature of 203°C to 223°C, the conversion rate of benzyl alcohol reached 72%, and the selectivity of benzaldehyde was greater than 98%. The catalyst has strict requirements on the control of the reaction temperature. When the temperature is higher than 250° C., the reactant will be completely oxidized to generate benzoic acid.

The current research status has prompted researchers to further develop a catalyst that takes into account the advantages of low temperature, high selectivity, high activity and wide temperature tolerance.

Ag-based supported catalysts are widely used in the addition of dimethyl oxalic acid due to the advantages of simple preparation method, highly dispersed active components, high activity, strong selectivity, high active surface area, and significantly lower price than Au-based catalysts. Hydrogen synthesis of methyl glycolate, oxidative elimination of formaldehyde, selective oxidation of alkyl-substituted aromatic hydrocarbons to synthesize ketones, ternary compound reaction of aldehydes-alkynes-amines, CO oxidation, selective oxidation of benzyl alcohol to prepare benzaldehyde and other reactions, and exhibited good catalytic performance.

Tsuruya et al. (Journal of Catalysis, 2005, 234:308-317) supported Ag on SiO ₂ by impregnation method, and used it in the gas-phase catalytic oxidation of benzyl alcohol to produce benzaldehyde. It was found that the Ag/SiO ₂ catalyst had good catalytic activity for the gas-phase oxidation of benzyl alcohol. When the reaction temperature is 320°C, the yield of benzaldehyde is 80%, and the selectivity is close to 100%. But the reaction temperature is much higher than the vaporization temperature of benzyl alcohol.

Sawayama et al. (Ind Eng Chem Res, 2006, 45:8837-8845) reported the application of Ag-supported catalysts in gas-phase catalytic oxidation of benzyl alcohol to benzaldehyde. In the literature, the author synthesized Ag-supported catalysts with different supports (SiO ₂ /CaO) and K/Ag/SiO ₂ catalysts based on the impregnation method. The effects of catalyst calcination temperature, reaction time and reaction temperature on catalyst activity were investigated systematically. The highest reaction yield reaches 84.2%. Although the catalyst has high selectivity to benzaldehyde at lower temperature, the conversion rate is not satisfactory.

Mao et al. (Catalysis Communication, 2009, 10:1376-1379) prepared a monolithic Ni microfiber structured material loaded with silver catalyst Ag/Ni-fiber by sintering-incipient wetness method, and used it for the gas-phase selective oxidation of alcohol Reacting. At a reaction temperature of 380°C, the conversion was 84% and the selectivity was 94%. Afterwards Deng et al. (AppliedCatalysis B: Environmental, 2010,99:222-228) of this research group attempted to adopt the pre-soaking method to prepare the Ag/Ni-fiber-M catalyst. When the reaction temperature was 300°C, it could be used The conversion rate and selectivity reach above 97%.

Jia et al. (Microporous Mesoporous Materials, 2012, 149:158) prepared Ag-HMS mesoporous molecular sieves by introducing silver active components in situ. When the reaction temperature was 310°C, the conversion rate of the catalyst to benzyl alcohol was close to 100. %, the selectivity of benzaldehyde can reach 96%, but the German silver grains in the Ag-HMS mesoporous molecular sieve are easy to agglomerate rapidly under high temperature conditions, resulting in a decrease in catalytic activity.

The above catalysts clearly show that Ag-based catalysts have good catalytic activity and selectivity for the gas-phase oxidation of benzyl alcohol, but it is still a challenge to reduce the reaction temperature on this basis.

CN102139224A discloses a catalyst for low-temperature gas-phase synthesis of benzaldehyde and its preparation method. M-Ag-HMS (M is an alkali metal, alkaline earth metal or rare earth metal element) is used as a catalyst, and the reaction temperature is 215°C to 220°C , the conversion rate of benzyl alcohol reached 94.71%, and the selectivity of benzaldehyde was 97.56%. However, the temperature tolerance of the catalyst is poor. When the reaction temperature is 320° C., the conversion rate of benzyl alcohol drops to 64.11%, and the selectivity of benzaldehyde is 95.53%. Ma et al. (Chinese Journal of Catalysis, 2013) prepared Ag/SBA-15 by impregnation method, and used it for the gas-phase selective oxidation of benzyl alcohol to synthesize benzaldehyde. When the reaction temperature was 240°C, the conversion rate and selectivity reached more than 94%. Due to the agglomeration, loss and carbon deposition of Ag during the reaction process, the service life is short.

In summary, the existing catalysts for the gas-phase selective catalytic oxidation of alcohols to prepare the corresponding aldehydes or ketones cannot take into account the advantages of low temperature, high selectivity, high activity, good temperature tolerance, low price and long service life, and The preparation process is complicated.

Contents of the invention

The present invention aims to solve the problem that the existing catalysts used for gas-phase selective catalytic oxidation of alcohols to prepare corresponding aldehydes or ketones cannot take into account low temperature, high selectivity, high activity, better temperature tolerance and longer service life, and provides The invention discloses a method for preparing benzaldehyde through the selective catalytic oxidation of benzyl alcohol in low-temperature gas phase by a bimetallic modified SBA-15 catalyst.

The molecular formula of the bimetallic modified SBA-15 catalyst of the present invention is xCu-yAg/SBA-15, wherein said x is the mass percentage of metal Cu in the catalyst, and x is 0.01% to 20%; said y is the mass percent content of metal Ag in the catalyst, and y is 1% to 30%.

The preparation method of bimetallic modified SBA-15 catalyst of the present invention, carries out according to the following steps:

Immerse the SBA-15 carrier in Cu ²⁺ /Ag ⁺ mixed aqueous solution, then magnetically stir for 2h to 24h at a temperature of 20°C to 100°C and a speed of 60rpm to 1000rpm, and filter to obtain solid catalyst, then place the obtained solid catalyst in an oven at a temperature of 50°C to 200°C for 1h to 48h, and then place it at a temperature of 400°C to 700°C for 1h to 24h to obtain a bimetallic modified SBA-15 Catalyst xCu-yAg/SBA-15; wherein said x is the mass percentage of metal Cu in the catalyst, and x is 0.01% to 20%; said y is the mass percentage of metal Ag in the catalyst, y is 1% to 30%; the cations in the Cu ²⁺ /Ag ⁺ mixed aqueous solution are Cu ²⁺ and Ag ⁺ , and the Cu ²⁺ concentration in the Cu ²⁺ /Ag ⁺ mixed aqueous solution is 0.001mol /L～5mol/L, the concentration of Ag ⁺ in the Cu ²⁺ /Ag ⁺ mixed aqueous solution is 0.001mol/L～5mol/L.

The application of the bimetallic modified SBA-15 catalyst of the present invention is that the bimetallic modified SBA-15 catalyst is used as a catalyst in the low-temperature gas-phase selective catalytic oxidation of alcohols to prepare corresponding aldehydes or ketones.

Advantages of the present invention:

1. The catalyst of the present invention is prepared by immersion method, and the synthesis process is simple; the interaction between metals makes the active components highly dispersed on the surface of the carrier, and the reduction of the metal load obviously shortens the production cost;

2. The catalyst of the present invention has high activity, strong selectivity, excellent catalytic performance, high product purity, and reduces the cost of separation and purification; and the catalyst has good temperature tolerance, and can be used in a wide temperature range (220° C. ~400℃), with stable catalytic performance, stable structure in gas phase continuous reaction, long service life and easy activation and regeneration;

3. The catalyst of the present invention is packed in a fixed-bed continuous reactor for the reaction of low-temperature gas-phase selective catalytic oxidation of alcohols to prepare corresponding aldehydes or ketones, which can realize low-temperature gas-phase high selectivity of alcohols under the premise of providing higher activity Oxidative synthesis of corresponding aldehydes or ketones, reducing energy consumption; it is beneficial to realize the industrial production of corresponding aldehydes or ketones by alcohol vapor phase oxidation, and meets the requirements of green chemical development;

4. The present invention uses oxygen as the oxygen source, and the by-product is water, which does not pollute the environment.

Detailed ways

Specific embodiment 1: The molecular formula of the bimetallic modified SBA-15 catalyst in this embodiment is xCu-yAg/SBA-15, wherein x is the mass percentage of metal Cu in the catalyst, and x is 0.01% to 20% %; said y is the mass percentage of metal Ag in the catalyst, and y is 1% to 30%.

The bimetallic modified SBA-15 catalyst of this embodiment is prepared by an impregnation method, and the catalyst introduces active components onto the surface of the SBA-15 carrier.

The catalyst described in this embodiment has high activity, strong selectivity, excellent catalytic performance, high product purity, and reduces the cost of separation and purification; and the catalyst has good temperature tolerance, and can be used in a wide temperature range (220 ℃～400℃), has stable catalytic performance, stable structure in gas phase continuous reaction, long service life and easy activation and regeneration.

Specific embodiment two: the preparation method of bimetallic modified SBA-15 catalyst of the present embodiment, carries out according to the following steps:

Immerse the SBA-15 carrier in Cu ²⁺ /Ag ⁺ mixed aqueous solution, then magnetically stir for 2h to 24h at a temperature of 20°C to 100°C and a speed of 60rpm to 1000rpm, and filter to obtain solid catalyst, then place the obtained solid catalyst in an oven at a temperature of 50°C to 200°C for 1h to 48h, and then place it at a temperature of 400°C to 700°C for 1h to 24h to obtain a bimetallic modified SBA-15 Catalyst xCu-yAg/SBA-15; wherein said x is the mass percentage of metal Cu in the catalyst, and x is 0.01% to 20%; said y is the mass percentage of metal Ag in the catalyst, y is 1% to 30%; the cations in the Cu ²⁺ /Ag ⁺ mixed aqueous solution are Cu ²⁺ and Ag ⁺ , and the Cu ²⁺ concentration in the Cu ²⁺ /Ag ⁺ mixed aqueous solution is 0.001mol /L～5mol/L, the concentration of Ag ⁺ in the Cu ²⁺ /Ag ⁺ mixed aqueous solution is 0.001mol/L～5mol/L.

In this embodiment, the impregnation method is used to prepare the catalyst, and the synthesis process is simple; the interaction between the metals makes the active components highly dispersed on the surface of the carrier, and the reduction of the metal load obviously shortens the production cost.

The catalyst prepared by this embodiment has high activity, strong selectivity, excellent catalytic performance, high product purity, and reduces the cost of separation and purification; and the catalyst has good temperature tolerance, and can be used in a wide temperature range (220 ° C) ~400℃), has stable catalytic performance, stable structure in gas phase continuous reaction, long service life and easy activation and regeneration.

The catalyst prepared in this embodiment is packed in a fixed-bed continuous reactor for the reaction of low-temperature gas-phase selective catalytic oxidation of alcohols to prepare corresponding aldehydes or ketones, which can achieve low-temperature gas-phase high selectivity of alcohols under the premise of providing higher activity Oxidative synthesis of corresponding aldehydes or ketones reduces energy consumption; it is beneficial to realize the industrial production of corresponding aldehydes or ketones by alcohol vapor phase oxidation, and meets the requirements of green chemical development.

In this embodiment, oxygen is used as the oxygen source, and the by-product is water, which does not pollute the environment.

Specific embodiment three: the difference between this embodiment and specific embodiment two is that: the anion in the Cu ²⁺ /Ag ⁺ mixed aqueous solution is or . Others are the same as in the second embodiment.

Embodiment 4: This embodiment differs from Embodiment 2 or Embodiment 3 in that: x is the mass percentage of metal Cu in the catalyst, and x is 0.1%-20%. Others are the same as the second or third specific embodiment.

Embodiment 5: This embodiment differs from Embodiment 2 to Embodiment 4 in that: y is the mass percentage of metal Ag in the catalyst, and y is 5% to 30%. Others are the same as one of the second to fourth specific embodiments.

Embodiment 6: The application of the bimetallic modified SBA-15 catalyst in this embodiment is that the bimetallic modified SBA-15 catalyst is used as a catalyst in the low-temperature gas-phase selective catalytic oxidation of alcohols to prepare corresponding aldehydes or ketones.

The method that the bimetallic modified SBA-15 catalyst is used as a catalyst in the preparation of corresponding aldehydes or ketones by the low-temperature gas-phase selective catalytic oxidation of alcohols is carried out in the following steps:

Put the bimetallic modified SBA-15 catalyst xCu-yAg/SBA-15 into the fixed-bed reactor at normal pressure, and inject the liquid alcohol into the preheating furnace at 206 ° C ~ 300 ° C by using the feeding pump to make the liquid alcohol completely Vaporization to obtain vaporized alcohol, then take the gas flow rate of the vaporized alcohol as X, the gas flow rate of oxygen in the oxygen source as Y and the gas flow rate of _N2 as Z to combine the vaporized alcohol, oxygen source and _N2 At the same time, it is passed into a fixed-bed reactor at normal pressure, and reacted continuously at a temperature of 210°C to 400°C to obtain the corresponding aldehyde or ketone; the gas flow rate X of the vaporized alcohol and the oxygen in the oxygen source The ratio of the gas flow Y of the gas is (0.01～10):1; the ratio of the gas flow Z of the _N2 to the gas flow Y of the oxygen in the oxygen source is (0.01～100):1; The feed ratio of the mass of the permanent SBA-15 catalyst xCu-yAg/SBA-15 to the mass of the vaporized alcohol is represented by the weight hourly space velocity, and the weight hourly space velocity is 0.01h ^-1 ~ 1000h ^-1 ; the oxygen source is oxygen Or a mixed gas containing oxygen with a volume fraction of m, where 50%≤m<100%.

The weight hourly space velocity (WHSV) described in this embodiment is the mass of the reaction material passing through the unit mass of the catalyst per unit time.

The synthesis process of the catalyst used in this embodiment is simple, and the pore structure is regular.

The catalyst prepared in this embodiment is packed in a fixed-bed continuous reactor for the reaction of low-temperature gas-phase selective catalytic oxidation of alcohols to prepare corresponding aldehydes or ketones, which can achieve low-temperature gas-phase high selectivity of alcohols under the premise of providing higher activity Oxidative synthesis of corresponding aldehydes or ketones reduces energy consumption; it is beneficial to realize the industrial production of corresponding aldehydes or ketones by alcohol vapor phase oxidation, and meets the requirements of green chemical development.

Specific embodiment seven: the difference between this embodiment and specific embodiment six is: the alcohol is benzyl alcohol, p-methyl benzyl alcohol, benzyl alcohol, cyclohexanol, cyclopentanol, cinnamyl alcohol, n-octanol, 1-phenylethanol or ethylene glycol. Others are the same as in the sixth embodiment.

Adopt following test to verify effect of the present invention:

Test one: the preparation method of bimetallic modified SBA-15 catalyst is carried out according to the following steps:

Immerse 1.0 g of SBA-15 support in 50 mL of a mixed solution containing Cu(NO ₃ ) ₂ 3H ₂ O (0.06 g) and AgNO ₃ (0.1 g), and then at a temperature of 50 ° C and a speed of 600 rpm Under the condition of magnetic stirring for 10 hours, filter to obtain a solid catalyst, then place the obtained solid catalyst in an oven with a temperature of 80 ° C for 24 hours, and then place it at a temperature of 500 ° C for 6 hours to obtain a bimetallic modified SBA- 15 Catalyst 1.5% Cu-6% Ag/SBA-15 (1.5% and 6% represent the mass percentages of Cu and Ag, respectively).

Test two: the preparation method of bimetallic modified SBA-15 catalyst is carried out according to the following steps:

Immerse 1.0 g of SBA-15 support in 50 mL of a mixed solution containing Cu(NO ₃ ) ₂ 3H ₂ O (0.02 g) and AgNO ₃ (0.1 g), and then at a temperature of 50 ° C and a speed of 600 rpm Under the condition of magnetic stirring for 10 hours, filter to obtain a solid catalyst, then place the obtained solid catalyst in an oven with a temperature of 80 ° C for 24 hours, and then place it at a temperature of 500 ° C for 6 hours to obtain a bimetallic modified SBA- 15 Catalyst 0.5% Cu-6% Ag/SBA-15 (0.5% and 6% respectively represent the mass percentages of Cu and Ag).

Test three: the preparation method of bimetallic modified SBA-15 catalyst is carried out according to the following steps:

Immerse 1.0 g of SBA-15 support in 50 mL of a mixed solution containing Cu(NO ₃ ) ₂ 3H ₂ O (0.04 g) and AgNO ₃ (0.1 g), and then at a temperature of 50 ° C and a speed of 600 rpm Under the condition of magnetic stirring for 10 hours, filter to obtain a solid catalyst, then place the obtained solid catalyst in an oven with a temperature of 80 ° C for 24 hours, and then place it at a temperature of 500 ° C for 6 hours to obtain a bimetallic modified SBA- 15 Catalyst 1.0% Cu-6% Ag/SBA-15 (1.0% and 6% represent the mass percentages of Cu and Ag, respectively).

Test four: the preparation method of bimetallic modified SBA-15 catalyst is carried out according to the following steps:

Immerse 1.0 g of SBA-15 support in 50 mL of a mixed solution containing Cu(NO ₃ ) ₂ 3H ₂ O (0.08 g) and AgNO ₃ (0.1 g), and then at a temperature of 50 ° C and a speed of 600 rpm Under the condition of magnetic stirring for 10 hours, filter to obtain a solid catalyst, then place the obtained solid catalyst in an oven with a temperature of 80 ° C for 24 hours, and then place it at a temperature of 500 ° C for 6 hours to obtain a bimetallic modified SBA- 15 Catalyst 2.0% Cu-6% Ag/SBA-15 (2.0% and 6% respectively represent the mass percentages of Cu and Ag).

Test five: Utilize the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low temperature gas phase selective catalytic oxidation of benzyl alcohol prepared by test one to prepare the method for benzaldehyde, carry out as follows:

Put 1.0g of 40 mesh to 60 mesh 1.5% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, and the vaporized benzyl alcohol, O _{and N} are simultaneously passed into the fixed-bed reactor at normal pressure, and the temperature is 240 °C for 2 hours, and the ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 96.2%, and the selectivity of benzaldehyde was 96.6%.

Test six: Utilize the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low temperature gas phase selective catalytic oxidation of benzyl alcohol prepared by test one to prepare the method for benzaldehyde, carry out as follows:

Put 1.0g of 40 mesh to 60 mesh 1.5% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, the vaporized benzyl alcohol, O _{and N} are passed into the normal pressure fixed bed reactor at the same time, and the temperature is 220 °C under the condition of reaction for 2h, ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 98.2%, and the selectivity of benzaldehyde was 92.6%.

Test seven: Utilize the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low-temperature gas phase selective catalytic oxidation of benzyl alcohol prepared by test one to prepare the method for benzaldehyde, carry out according to the following steps:

Put 1.0g of 40 mesh to 60 mesh 1.5% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, and the vaporized benzyl alcohol, O _{and N} are simultaneously passed into the fixed-bed reactor at normal pressure, and the temperature is 260 °C for 2 hours, and the ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 95.2%, and the selectivity of benzaldehyde was 96.3%.

Test eight: Utilize the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low temperature gas phase selective catalytic oxidation of benzyl alcohol prepared by test one to prepare the method for benzaldehyde, carry out as follows:

Put 1.0g of 40 mesh to 60 mesh 1.5% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, and the vaporized benzyl alcohol, O _{and N} are simultaneously introduced into the fixed-bed reactor at normal pressure, and the temperature is 280°C for 2 hours, and the ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 95.6%, and the selectivity of benzaldehyde was 96.8%.

Test nine: utilize the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low temperature gas phase selective catalytic oxidation of benzyl alcohol prepared by test one to prepare the method for benzaldehyde, carry out as follows:

Put 1.0g of 40 mesh to 60 mesh 1.5% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, and the vaporized benzyl alcohol, O _{and N} are simultaneously passed into the fixed-bed reactor at normal pressure, and the temperature is 300 °C for 2 hours, and the ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 96.9%, and the selectivity of benzaldehyde was 96.4%.

Test ten: Utilize the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low temperature gas phase selective catalytic oxidation of benzyl alcohol prepared by test one to prepare the method for benzaldehyde, carry out as follows:

Put 1.0g of 40 mesh to 60 mesh 1.5% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, and the vaporized benzyl alcohol, O _{and N} are simultaneously passed into the fixed-bed reactor at normal pressure, and the temperature is 320 °C for 2 hours, and the ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 97.3%, and the selectivity of benzaldehyde was 93.4%.

Test eleven: the method for preparing benzaldehyde by using the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of benzyl alcohol prepared by test one is carried out as follows:

Put 1.0g of 40 mesh to 60 mesh 1.5% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, and the vaporized benzyl alcohol, O _{and N} are simultaneously passed into the fixed-bed reactor at normal pressure, and the temperature is 340°C for 2 hours, and the ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 96.9%, and the selectivity of benzaldehyde was 93.1%.

Test 12: the method for preparing benzaldehyde by using the bimetallic modified SBA-15 catalyst 0.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of benzyl alcohol prepared by test two is carried out in the following steps:

Put 1.0g of 40 mesh to 60 mesh 0.5% Cu-6% Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm, and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, and the vaporized benzyl alcohol, O _{and N} are simultaneously passed into the fixed-bed reactor at normal pressure, and the temperature is 240 °C for 2 hours, and the ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 94.2%, and the selectivity of benzaldehyde was 95.6%.

Experiment 13: The method for preparing benzaldehyde by using the bimetallic modified SBA-15 catalyst 1.0%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of benzyl alcohol prepared in Experiment 3 is carried out according to the following steps:

Put 1.0g of 40 mesh to 60 mesh 1.0% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm, and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, and the vaporized benzyl alcohol, O _{and N} are simultaneously passed into the fixed-bed reactor at normal pressure, and the temperature is 240 °C for 2 hours, and the ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 94.8%, and the selectivity of benzaldehyde was 95.9%.

Test fourteen: the method for preparing benzaldehyde by using the bimetallic modified SBA-15 catalyst 2.0%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of benzyl alcohol prepared by test four is carried out as follows:

Put 1.0g of 40 mesh to 60 mesh 2.0% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand into the normal pressure fixed bed reactor (the inner diameter of the reaction tube is 6mm and the length is 450mm) , using a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at a rate of 0.10mL/min and _O2 flow 13mL/min, N _The flow rate is 38mL/min, and the vaporized benzyl alcohol, O _{and N} are simultaneously passed into the fixed-bed reactor at normal pressure, and the temperature is 240 °C for 2 hours, and the ice-salt bath ( -10° C. to -15° C.) collected gas phase products and unreacted benzyl alcohol, and analyzed the collected products by FID gas chromatography. The conversion rate of benzyl alcohol was 89.8%, and the selectivity of benzaldehyde was 93.9%.

Experiment 15: The method for preparing p-tolualdehyde by using the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of p-methylbenzyl alcohol prepared in experiment 1, as follows Steps to proceed:

The 40 mesh ~ 60 mesh quartz sand of 1.0g 40 mesh ~ 60 mesh bimetallic modification catalyst 1.5% Cu-6% Ag/SBA-15 mixed 4g is packed in the normal pressure fixed bed reactor (reaction tube internal diameter is 6mm , length is 450mm), utilize feeding pump to inject liquid p-methyl benzyl alcohol into the preheating furnace of 220 ℃ to make liquid p-methyl benzyl alcohol completely vaporize, obtain the p-methyl benzyl alcohol after vaporization, then use the vaporized p-methyl benzyl alcohol The feed rate of p-methylbenzyl alcohol is 0.10mL/min, the _O2 flow rate is 13mL/min, and the _N2 flow rate _is 38mL/min _. In a bed reactor, react at a temperature of 300°C for 2h, collect gaseous products and unreacted p-methylbenzyl alcohol in an ice-salt bath (-10°C to -15°C), and analyze the collected product by FID gas chromatography Analysis shows that the p-methylbenzyl alcohol conversion rate is 93.5%, and the p-tolualdehyde selectivity is 97.6%.

Experiment 16: The method for preparing benzophenone by using the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of diphenylmethanol prepared in experiment 1 is carried out according to the following steps:

The 40 mesh ~ 60 mesh quartz sand of 1.0g 40 mesh ~ 60 mesh bimetallic modification catalyst 1.5% Cu-6% Ag/SBA-15 mixed 4g is packed in the normal pressure fixed bed reactor (reaction tube internal diameter is 6mm , length is 450mm), utilize feeding pump to inject liquid diphenyl alcohol into the preheating furnace of 300 ℃ to make liquid diphenyl alcohol vaporize completely, obtain the diphenyl alcohol after vaporization, then with the feeding speed of diphenyl alcohol after vaporization 0.10mL/min, O ₂ flow rate 13mL/min, N ₂ flow rate 38mL/min, the vaporized diphenylmethanol, O ₂ and N ₂ are passed into the fixed bed reactor at normal pressure at the same time, at a temperature of 320°C Under the conditions of reaction for 2h, the gas phase product and unreacted diphenylmethanol were collected in an ice-salt bath (-10 ° C ~ -15 ° C), and the collected product was analyzed by FID gas chromatography. The conversion rate of diphenyl alcohol was 87.2%. Benzophenone selectivity is 93.6%.

Experiment 17: The method for preparing cyclohexanone by using the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of cyclohexanol prepared in Experiment 1 is carried out as follows:

1.0g of 40 mesh to 60 mesh bimetallic modified catalyst 1.5% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand was packed into an atmospheric fixed bed reactor (the internal diameter of the reaction tube was 6 mm, length is 450mm), utilize feeding pump to squeeze liquid cyclohexanol into the preheating furnace of 180 ℃ to make liquid cyclohexanol vaporize completely, obtain vaporized cyclohexanol, then with the vaporized cyclohexanol feed rate as 0.10mL/min, O ₂ flow rate 13mL/min, N ₂ flow rate 38mL/min, the vaporized cyclohexanol, O ₂ and N ₂ were passed into the fixed bed reactor at normal pressure at the same time. Under the conditions of reaction for 2 hours, the gas phase product and unreacted cyclohexanol were collected in an ice-salt bath (-10 ° C ~ -15 ° C), and the collected product was analyzed by FID gas chromatography. The conversion rate of cyclohexanol was 78.2%. The ketone selectivity was 90.6%.

Experiment 18: The method for preparing cyclopentanone by using the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of cyclopentanol prepared in Experiment 1 is carried out according to the following steps:

The 40 mesh ~ 60 mesh quartz sand of 1.0g 40 mesh ~ 60 mesh bimetallic modification catalyst 1.5% Cu-6% Ag/SBA-15 mixed 4g is packed in the normal pressure fixed bed reactor (reaction tube internal diameter is 6mm , length is 450mm), utilize feeding pump to squeeze liquid cyclopentanol into the preheating furnace of 150 ℃ to make liquid cyclopentanol vaporize completely, obtain cyclopentanol after vaporization, then with the cyclopentanol feed rate after vaporization 0.10mL/min, O ₂ flow rate 13mL/min, N ₂ flow rate 38mL/min, the vaporized cyclopentanol, O ₂ and N ₂ are simultaneously passed into the fixed bed reactor at normal pressure, at a temperature of 300°C The reaction was carried out for 2 hours under certain conditions, and the gas phase product and unreacted cyclopentanol were collected in an ice-salt bath (-10°C to -15°C). The collected product was analyzed by FID gas chromatography, and the conversion rate of cyclopentanol was 88.2%. Pentanone selectivity was 85.6%.

Experiment 19: The method for preparing n-octanal by using the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of n-octanol prepared in the first experiment is carried out according to the following steps:

The 40 mesh ~ 60 mesh quartz sand of 1.0g 40 mesh ~ 60 mesh bimetallic modification catalyst 1.5% Cu-6% Ag/SBA-15 mixed 4g is packed in the normal pressure fixed bed reactor (reaction tube internal diameter is 6mm , length is 450mm), utilize feeding pump to drive liquid n-octanol into the preheating furnace of 200 ℃ to make liquid n-octanol vaporize completely, obtain n-octanol after vaporization, then use the n-octanol feed rate after vaporization 0.10mL/min, O ₂ flow rate 13mL/min, N ₂ flow rate 38mL/min, the vaporized n-octanol, O ₂ and N ₂ are simultaneously passed into the fixed bed reactor at normal pressure, at a temperature of 300°C The reaction was carried out for 2 hours under certain conditions, and the gas phase product and unreacted n-octanol were collected in an ice-salt bath (-10°C to -15°C). The collected product was analyzed by FID gas chromatography, and the conversion rate of n-octanol was 79.2%. Octanal selectivity was 89.3%.

Experiment 20: The method for preparing glyoxal by using the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of ethylene glycol prepared in experiment 1 is carried out according to the following steps:

The 40 mesh ~ 60 mesh quartz sand of 1.0g 40 mesh ~ 60 mesh bimetallic modification catalyst 1.5% Cu-6% Ag/SBA-15 mixed 4g is packed in the normal pressure fixed bed reactor (reaction tube internal diameter is 6mm , length is 450mm), use the feeding pump to inject the liquid ethylene glycol into the preheating furnace at 210 ℃ to completely vaporize the liquid ethylene glycol to obtain the vaporized ethylene glycol, and then use the feed rate of the vaporized ethylene glycol 0.10mL/min, O ₂ flow rate 13mL/min, N ₂ flow rate 38mL/min, the vaporized ethylene glycol, O ₂ and N ₂ are simultaneously passed into the fixed bed reactor at normal pressure, at a temperature of 300°C The reaction was carried out for 2 hours under certain conditions, and the gas phase product and unreacted ethylene glycol were collected in an ice-salt bath (-10°C to -15°C). The collected product was analyzed by FID gas chromatography, and the conversion rate of ethylene glycol was 69.2%. Dialdehyde selectivity was 79.8%.

Experiment 21: The method of preparing cinnamaldehyde by using the bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selective catalytic oxidation of cinnamyl alcohol prepared in experiment 1 is carried out according to the following steps:

The 40 mesh ~ 60 mesh quartz sand of 1.0g 40 mesh ~ 60 mesh bimetallic modification catalyst 1.5% Cu-6% Ag/SBA-15 mixed 4g is packed in the normal pressure fixed bed reactor (reaction tube internal diameter is 6mm , length is 450mm), utilize feeding pump to squeeze liquid cinnamyl alcohol into the preheating furnace of 200 ℃ to make liquid cinnamyl alcohol completely vaporize, obtain the cinnamyl alcohol after vaporization, the feed rate of cinnamyl alcohol after vaporization is 0.10mL/min, The flow rate of O ₂ is 13mL/min, and the flow rate of N ₂ is 38mL/min. The vaporized cinnamyl alcohol, O ₂ and N ₂ are simultaneously passed into the fixed-bed reactor at normal pressure, and the reaction is carried out at a temperature of 300°C for 2 hours. Gas phase products and unreacted cinnamyl alcohol were collected in a salt bath (-10°C to -15°C), and the collected product was analyzed by FID gas chromatography. The conversion rate of cinnamyl alcohol was 83.4%, and the selectivity of cinnamaldehyde was 78.3%.

Claims (4)

1. The method for preparing benzaldehyde by bimetallic modified SBA-15 catalyst low temperature gas phase selective catalytic oxidation of benzyl alcohol, characterized in that bimetallic modified SBA-15 catalyst 1.5%Cu-6%Ag/SBA-15 low temperature gas phase selectivity The method for preparing benzaldehyde by catalytic oxidation of benzyl alcohol is completed in the following steps: 1.0g of 40 mesh to 60 mesh 1.5% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand is loaded into the normal pressure fixed bed reactor, and the reaction of the normal pressure fixed bed reactor The inner diameter of the tube is 6mm, and the length is 450mm. Use a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at the rate of 0.10mL/min, O ₂ flow rate 13mL/min, N ₂ flow rate 38mL/min, the vaporized benzyl alcohol, O ₂ and N ₂ were passed into the normal pressure fixed bed reactor at the same time, at a temperature of 240°C The reaction was carried out under the conditions for 2 hours, and the gas phase product and unreacted benzyl alcohol were collected in an ice-salt bath at a temperature of -10°C to -15°C, and the collected product was analyzed by FID gas chromatography. 2. The method for preparing benzaldehyde by bimetallic modified SBA-15 catalyst low-temperature gas-phase selective catalytic oxidation of benzyl alcohol, characterized in that bimetallic modified SBA-15 catalyst 0.5%Cu-6%Ag/SBA-15 low-temperature gas-phase selectivity The method for preparing benzaldehyde by catalytic oxidation of benzyl alcohol is completed in the following steps: 1.0g of 40 mesh to 60 mesh 0.5% Cu-6% Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand is loaded into the normal pressure fixed bed reactor, and the reaction of the normal pressure fixed bed reactor The inner diameter of the tube is 6mm, and the length is 450mm. Use a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at the rate of 0.10mL/min, O ₂ flow rate 13mL/min, N ₂ flow rate 38mL/min, the vaporized benzyl alcohol, O ₂ and N ₂ were passed into the normal pressure fixed bed reactor at the same time, at a temperature of 240°C The reaction was carried out under the conditions for 2 hours, and the gas phase product and unreacted benzyl alcohol were collected in an ice-salt bath at a temperature of -10°C to -15°C, and the collected product was analyzed by FID gas chromatography. 3. The method for preparing benzaldehyde by bimetallic modified SBA-15 catalyst low temperature gas phase selective catalytic oxidation of benzyl alcohol, characterized in that the bimetallic modified SBA-15 catalyst 1.0%Cu-6%Ag/SBA-15 low temperature gas phase selectivity The method for preparing benzaldehyde by catalytic oxidation of benzyl alcohol is completed in the following steps: 1.0g of 40 mesh to 60 mesh 1.0% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand is loaded into the normal pressure fixed bed reactor, and the reaction of the normal pressure fixed bed reactor The inner diameter of the tube is 6mm, and the length is 450mm. Use a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at the rate of 0.10mL/min, O ₂ flow rate 13mL/min, N ₂ flow rate 38mL/min, the vaporized benzyl alcohol, O ₂ and N ₂ were passed into the normal pressure fixed bed reactor at the same time, at a temperature of 240°C The reaction was carried out under the conditions for 2 hours, and the gas phase product and unreacted benzyl alcohol were collected in an ice-salt bath at a temperature of -10°C to -15°C, and the collected product was analyzed by FID gas chromatography. 4. The method for preparing benzaldehyde by bimetallic modified SBA-15 catalyst low temperature gas phase selective catalytic oxidation of benzyl alcohol, characterized in that the bimetallic modified SBA-15 catalyst 2.0%Cu-6%Ag/SBA-15 low temperature gas phase selectivity The method for preparing benzaldehyde by catalytic oxidation of benzyl alcohol is carried out in the following steps: 1.0g of 40 mesh to 60 mesh 2.0% Cu-6%Ag/SBA-15 mixed with 4g of 40 mesh to 60 mesh quartz sand is loaded into the normal pressure fixed bed reactor, and the reaction of the normal pressure fixed bed reactor The inner diameter of the tube is 6mm, and the length is 450mm. Use a feeding pump to inject liquid benzyl alcohol into a preheating furnace at 220°C to completely vaporize the liquid benzyl alcohol to obtain vaporized benzyl alcohol, and then feed the vaporized benzyl alcohol at the rate of 0.10mL/min, O ₂ flow rate 13mL/min, N ₂ flow rate 38mL/min, the vaporized benzyl alcohol, O ₂ and N ₂ were passed into the normal pressure fixed bed reactor at the same time. React for 2 hours under the same conditions, collect gaseous products and unreacted benzyl alcohol in an ice-salt bath at a temperature of -10° C. to -15° C., and analyze the collected products by FID gas chromatography.