阅读说明：本技术 一种负载型等离激元纳米合金光催化剂 (Supported plasmon nano-alloy photocatalyst ) 是由 韩鹏飞 李昆 于 2020-12-08 设计创作，主要内容包括：本发明公开了一种用于选择性氧化的等离激元合金纳米光催化剂及其制备方法和应用,该催化剂由禁带宽度大于4.0eV的金属氧化物和等离激元型合金纳米颗粒组成。该催化剂能高效利用大于400nm波长的激发光谱,通过改变合金中金属组分可以调控催化材料的能带结构,激发丰富的热电子来活化空气气氛中的氧气分子,达到高效选择性催化醇类氧化的目的。(The invention discloses a plasmon alloy nano photocatalyst for selective oxidation and a preparation method and application thereof, wherein the catalyst is composed of metal oxide with the forbidden bandwidth larger than 4.0eV and plasmon alloy nano particles. The catalyst can efficiently utilize excitation spectrum with the wavelength of more than 400nm, can regulate and control the energy band structure of a catalytic material by changing metal components in the alloy, and excites abundant hot electrons to activate oxygen molecules in air atmosphere, thereby achieving the purpose of efficiently and selectively catalyzing alcohol oxidation.)

1. A supported plasmon nanometer alloy photocatalyst comprises a binary nanometer alloy and a metal oxide carrier, wherein the binary nanometer alloy accounts for 0.5-20% of the mass of the metal oxide carrier; the binary nano alloy consists of a plasmon metal A and another non-plasmon metal B, wherein the metal A is selected from one of silver (Ag) and copper (Cu), and the metal B is selected from one of palladium (Pd), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), nickel (Ni) and cobalt (Co), and is characterized in that A accounts for 50-66% of the total atomic number in the alloy.

2. The supported plasmonic nanoalloy photocatalyst of claim 1 or 2, wherein the metal oxide forbidden band width is greater than 4.0eV and is selected from alumina (Al)₂O₃) Zirconium oxide (ZrO)₂) Silicon oxide (SiO)₂) Zeolite-like materials (zeolites).

3. The use of the supported plasmonic nanoalloy photocatalyst of claim 1 or 2 in the reaction of direct oxidation of a primary alcohol to an ester product.

4. The supported plasmonic nanoalloy photocatalyst of claim 1 or 2, wherein the method of preparation comprises the steps of:

1) pre-dispersing the metal oxide carrier in water or glycol solution by stirring or ultrasonic method, adding water or glycol solution (10mM) of A and B metal precursors according to a specific proportion, and blending for 10min-2 h.

2) Controlling the blending solution to a specified temperature (0-150 ℃), blending at a speed of 0.1-10 mL/min with one of hydrazine hydrate, ammonium formate, sodium borohydride, potassium borohydride and formaldehyde aqueous solution (0.01-10M) under the stirring condition, or co-reducing metal ions in the mixed solution without adding an additional reducing agent (when the reducing agent is ethylene glycol) to obtain a supported alloy catalyst suspension.

3) And filtering the upper suspension, washing the obtained solid with deionized water twice and ethanol once, and drying for 24 hours at the temperature of 60 ℃ under a vacuum condition to obtain the required catalyst.

5. A method for driving selective esterification of primary alcohol by photocatalysis is characterized in that: the method aims at the target reaction of a primary alcohol (R)₁CHOH) or a primary alcohol (R)₁CHOH) with another monohydric alcohol (R)₂CHOHR₃) By cross-condensation of (a) wherein R₁The group is selected from one of aryl, aralkyl and alkyl or derivatives thereof, R₂、R₃One selected from aryl, aralkyl, alkyl and hydrogen, and the selective oxidation product is ester (R)₁CHOOCHR₁Or R₁CHOOCHR₂R₃) (ii) a The method comprises the steps that the supported plasmon nano-alloy photocatalyst is prepared according to the claim 1 or 2, and the amount of the catalyst corresponding to each milliliter of reaction liquid is 2.5-50 mg; in the method, the reaction is carried out in a toluene organic solvent or monohydric alcohol, an alkaline additive is required to be added in the reaction, the reaction atmosphere is an air atmosphere, the emission wavelength of a light source is more than 400nm, and the light intensity range is 0.1-1.5W-cm^-2The reaction temperature of the light source is 15-100 ℃, and the reaction time is 10min-20 h.

6. The method of claim 5, wherein the toluene-based organic solvent is trifluorotoluene or toluene.

7. The method of claim 5, wherein the basic additive is one of potassium carbonate, sodium carbonate, cesium carbonate, lithium carbonate, potassium hydroxide, sodium hydroxide, lithium hydroxide, and potassium phosphate.

The technical field is as follows: the invention relates to a plasmon alloy nano photocatalyst for selective oxidation and a preparation method and application thereof, belonging to the technical field of photocatalysis.

Background art: the oxidation reaction is an important component in the chemical synthesis process, and can be used for preparing various chemicals such as alcohol, phenol, aldehyde, ketone, quinone, acid, epoxy compound, peroxy compound, nitrile and the like. In the traditional oxidation process, inorganic/organic oxides such as potassium permanganate, potassium dichromate, aluminum isopropoxide and the like which are equivalent to reaction substrates are often used, and the problems of difficult preparation and separation or environmental harm exist. Therefore, attention is increasingly paid to the development of new methods for catalytic oxidation, which can fully utilize organic raw materials, save energy, reduce consumption and are environment-friendly. Wherein the use of molecular oxygen, an easily available and environmentally benign oxidant, meets the requirements of green chemistry as well as atomic economy. The use of molecular oxygen as an oxidant source in the preparation of commodity chemicals and bulk chemicals is currently in large-scale use, with about 200 million tons of related chemicals being synthesized each year. However, in the fine chemical and pharmaceutical industries, the use of molecular oxygen as an oxidizing agent is difficult to achieve. This is mainly due to the kinetic inertness of molecular oxygen, which usually requires severe conditions such as high temperature and high pressure to activate it, thus requiring the use of special production equipment and increasing the risk of running the reaction, and at the same time making the overall catalytic process difficult to control, which easily results in the formation of by-products.

In many alternative catalytic systems, light is a green and easily regulated energy input. Fujishima and Honda in the seventies of the last century discovered that semiconductors can photo-catalyze the decomposition of water, and the field starts to develop rapidly. In recent decades, photocatalytic systems using plasmonic structures as a medium have been rapidly developed. Different from semiconductors, under the illumination condition, plasmon structures such as gold, silver, copper and other nano particles have a Localized Surface Plasmon Resonance (LSPR) effect and can strongly absorb visible light, and the light absorption cross section is far larger than the physical cross section, so that the sunlight spectrum can be more fully utilized. In addition, when the temperature of a catalytic system rises, the photoproduction electron-hole of the semiconductor is easier to recombine, the conversion efficiency from light energy to chemical energy is reduced, and the plasmon structure can accelerate the reaction by using the thermal effect. More importantly, the LSPR effect can promote the generation of hot electrons on the surface of the plasmonic structure, and the number and energy level of the electrons can be adjusted by changing the intensity and wavelength of incident light. The unique properties of the plasmon structure are beneficial to activating oxygen molecules to participate in the reaction under the relatively mild condition of a related catalytic system, and the generation of byproducts is reduced.

This plasmonic structure-non-semiconductor strategy was first reported in 2008 for efficient photocatalysis (angelw. chem. int. ed.,2008,47, 5353-. Subsequently, a series of alloy-type plasmonic photocatalysts derived from this strategy were developed to widen the application range in the field of organic small molecule synthesis. These applications include coupling reactions (ACS Catal.,2014,4, 1725-. The production of corresponding esters by using primary alcohols as substrates usually requires an intermediate product of aldehydes, and requires a catalyst to effectively activate oxygen molecules to participate in the reaction, and relatively harsh reaction conditions (such as high temperature and pure oxygen conditions) are required to improve the selectivity of the produced esters. Aiming at the problems, the invention preferably selects the plasmon metals such as Ag, Cu and the like which can fully act with oxygen molecules, introduces the second metal for alloying according to the electron energy band theory, enables the catalyst to generate abundant high-energy electrons under the illumination of more than 400nm to participate in the activation of the oxygen molecules by controlling the proportion of the plasmon metals and the second metal, drives the primary alcohol to directly generate ester compounds under mild conditions (low reaction temperature and air atmosphere) without generating aldehyde intermediate products basically, and achieves the purpose of improving the reaction selectivity.

The invention content is as follows:

the supported plasmon nanometer alloy photocatalyst comprises a binary nanometer alloy and a metal oxide carrier, wherein the binary nanometer alloy accounts for 0.5-20% of the metal oxide carrier by mass percent; the binary nano alloy consists of a plasmon metal A and another non-plasmon metal B, wherein the metal A is selected from one of silver (Ag) and copper (Cu), and the metal B is selected from one of palladium (Pd), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), nickel (Ni) and cobalt (Co), and is characterized in that A accounts for 50-66% of the total atomic number in the alloy.

The preferred metal oxide has a forbidden band width greater than 4.0eV and is selected from the group consisting of alumina (Al)₂O₃) Zirconium oxide (ZrO)₂) Silicon oxide (SiO)₂) Zeolite-like materials (zeolites).

The invention also provides application of the supported plasmon nanometer alloy photocatalyst in the reaction of directly oxidizing primary alcohol into an ester product.

The invention also provides a preparation method of the supported plasmon nanometer alloy photocatalyst, which mainly comprises the following steps:

1) pre-dispersing the metal oxide carrier in water or glycol solution by stirring or ultrasonic method, adding water or glycol solution (10mM) of A and B metal precursors according to a specific proportion, and blending for 10min-2 h.

2) Controlling the blending solution to a specified temperature (0-150 ℃), blending at a speed of 0.1-10 mL/min with one of hydrazine hydrate, ammonium formate, sodium borohydride, potassium borohydride and formaldehyde aqueous solution (0.01-10M) under the stirring condition, or co-reducing metal ions in the mixed solution without adding an additional reducing agent (when the reducing agent is ethylene glycol) to obtain a supported alloy catalyst suspension.

3) And filtering the upper suspension, washing the obtained solid with deionized water twice and ethanol once, and drying for 24 hours at the temperature of 60 ℃ under a vacuum condition to obtain the required catalyst.

The invention also relates to a method for driving the selective esterification of primary alcohol by photocatalysis, and the method aims at the target reaction of primary alcohol (R)₁CHOH) or a primary alcohol (R)₁CHOH) with another monohydric alcohol (R)₂CHOHR₃) By cross-condensation of (a) wherein R₁The group is selected from one of aryl, aralkyl and alkyl or derivatives thereof, R₂、R₃One selected from aryl, aralkyl, alkyl and hydrogen, and the selective oxidation product is ester (R)₁CHOOCHR₁Or R₁CHOOCHR₂R₃) (ii) a The above-mentionedThe method comprises the steps of preparing the supported plasmon nanometer alloy photocatalyst; the amount of the catalyst corresponding to each milliliter of reaction solution is 2.5-50 mg; in the method, the reaction is carried out in a toluene organic solvent or monohydric alcohol, an alkaline additive is required to be added in the reaction, the reaction atmosphere is an air atmosphere, the emission wavelength of a light source is more than 400nm, and the light intensity range is 0.1-1.5W-cm^-2The reaction temperature of the light source is 15-100 ℃, and the reaction time is 10min-20 h.

The preferred toluene-based organic solvent is trifluorotoluene or toluene.

The preferred alkaline additive is one of potassium carbonate, sodium carbonate, cesium carbonate, lithium carbonate, potassium hydroxide, sodium hydroxide, lithium hydroxide, potassium phosphate.

Compared with the prior art, the invention has the beneficial effects that: by utilizing the plasmon alloy nanoparticles and controlling the proportion of non-plasmon metals in the alloy, the d-band position of the plasmon metals such as Ag and Cu is improved, so that the alloy nanoparticles generate inter-band-in-band cooperative electronic transition under the illumination of more than 400nm, the photon utilization rate is improved, oxygen molecules in the air are converted into active oxygen, primary alcohol is driven to be converted into ester with high selectivity, and no intermediate products such as aldehyde are generated basically.

Description of the drawings:

FIG. 1: ZrO (ZrO)₂Loaded with 5 wt.% AgNi_0.7Transmission electron microscopy of alloy nanoparticles.

FIG. 2: ZrO (ZrO)₂Supporting 3 wt.% AgPd_0.6Transmission electron microscopy of alloy nanoparticles.

FIG. 3: al (Al)₂O₃Transmission electron microscopy images of 1 wt.% loaded CuPt alloy nanoparticles.

FIG. 4: al (Al)₂O₃Loaded with 4 wt.% AgCo_0.8Transmission electron microscopy of alloy nanoparticles.

FIG. 5: ZrO (ZrO)₂Supporting 3 wt.% AgPd_0.6And (3) driving a benzyl alcohol esterification reaction gas chromatography analysis result by the alloy nanoparticles.

FIG. 6: al (Al)₂O₃Gas chromatography for driving esterification reaction of 3-methylbenzyl alcohol by loading 1 wt.% of CuPt alloy nanoparticlesAnd (6) analyzing the result.

The specific implementation mode is as follows:

example 1:

ZrO₂AgNi load_0.7Alloy preparation and application:

0.1g of ZrO was weighed₂30mL of deionized water was added and dispersed by ultrasonic for 5 min. Adding 3.4mL AgNO while stirring at high speed₃Aqueous solution (10mM), 2.3mL Ni (NO)₃)₂Stirring the aqueous solution (10mM) for 30min, placing the solution in an ice-water mixed bath, controlling the temperature to 5 ℃, and dropwise adding 13mL of NaBH at the rate of 1mL/min₄The aqueous solution (0.038M) was stirred at room temperature for 1h and then the stirring was stopped. Standing and aging the suspension for 20 hours at room temperature, filtering with quick filter paper to obtain a solid, washing twice with deionized water and twice with ethanol, placing at 60 ℃ and vacuum drying for 24 hours to obtain AgNi with alloy loading of about 5% relative to the mass of the carrier_0.7/ZrO₂A catalyst. (FIG. 1: As shown in FIG. 1, AgNi_0.7The nano particles are densely distributed in ZrO₂Surface of carrier, AgNi_0.7The alloy nanoparticles are about 5nm in size. )

50mg of dried AgNi was weighed_0.7/ZrO₂Adding the catalyst into a glass reaction bottle, adding 10mL of 1-butanol trifluorotoluene solution (1M), adding 10mmol of NaOH, sealing, and placing the glass reactor in a xenon lamp light source (400-800nm, 1.2W cm)^-2) The reaction is carried out for 20h at the temperature of 40 ℃. After the reaction, the reaction solution was filtered through an organic filter membrane with a pore size of 0.22 μm to obtain a solution containing the product, and the conversion rate of 1-butanol was 85% and the selectivity of butyl butyrate was 95% by quantitative analysis by GC.

Example 2:

ZrO₂AgPd loading_0.6Alloy preparation and application:

0.05g of ZrO was weighed₂50mL of ethylene glycol was added and dispersed by sonication for 20 min. Adding 0.87mL AgNO while stirring at high speed₃Ethylene glycol solution (10mM), 0.52mL Ni (NO)₃)₂And stirring the ethylene glycol solution (10mM), placing the mixture in an oil bath kettle to be heated to 140 ℃ after stirring for 10min, stirring for reaction for 1h, and stopping heating and stirring. After the solution was cooled to room temperature, it was filtered through quick filter paper,obtaining solid matter, washing twice with deionized water and twice with ethanol, placing the solid matter in a vacuum drying chamber at 60 ℃ for 24 hours to obtain AgPd with the alloy loading capacity of about 3 percent relative to the mass of the carrier_0.6/ZrO₂A catalyst. (FIG. 2: As shown in FIG. 2, AgPd_0.6The nano particles are uniformly dispersed in the ZrO₂Surface of carrier, AgPd_0.6The size of the alloy nano particles is about 3nm, and no obvious agglomeration phenomenon exists. )

Weighing 1mg of dried AgPd_0.6/ZrO₂The catalyst was added to a glass reaction flask, 1mL of benzyl alcohol in methanol (0.1M) was added, and 0.1mmol of Na was added₂CO₃Sealing, placing the glass reactor in an LED light source (410 + -5 nm, 0.7W cm)^-2) The reaction is carried out for 40min at 70 ℃. After the reaction, the reaction solution was filtered through an organic filter having a pore size of 0.22 μm to obtain a solution containing the product, and the reaction conversion was 89% and the selectivity to methyl benzoate was 97% by quantitative analysis by GC. (FIG. 5: as shown in FIG. 5, the liquid phase product after filtration was analyzed by gas chromatography, and found to be benzaldehyde and methyl benzoate as the main products, and a small amount of benzyl alcohol residue was detected.A conversion (initial concentration of benzyl alcohol-concentration of benzyl alcohol after reaction)/initial concentration of benzyl alcohol, a selectivity (methyl benzoate concentration/(methyl benzoate concentration + concentration of benzaldehyde), and concentrations of benzyl alcohol, methyl benzoate, and benzaldehyde were calibrated by an external standard method.)

Example 3:

Al₂O₃preparation and application of the loaded CuPt alloy:

0.1g of ZrO was weighed₂30mL of deionized water was added and the mixture was ultrasonically dispersed for 20 min. Adding 0.39mL AgNO while stirring at high speed₃Aqueous solution (10mM), 0.39mL HPtCl₆Stirring the aqueous solution (10mM), placing the solution in an oil bath kettle after stirring for 50min, heating the solution to 70 ℃, slowly adding NaOH solution (1M) to enable the pH value of the solution to reach 13, dropwise adding 0.7mL of formaldehyde aqueous solution (3M) at the speed of 0.1mL/min, continuously stirring for 1h, fully reacting, and stopping stirring. Cooling the suspension to room temperature, filtering with rapid filter paper to obtain solid, washing with deionized water twice, washing with ethanol twice, vacuum drying at 60 deg.C for 24 hr to obtain alloy with loading amount of about 1% of the carrierCuPt/Al₂O₃A catalyst. (FIG. 3: As shown in FIG. 3, the CuPt nanoparticles are sparsely dispersed in gamma-Al₂O₃The size of the CuPt alloy nanoparticles on the surface of the carrier is about 10 nm. )

5mg of dried CuPt/Al was weighed₂O₃The catalyst was added to a glass reaction flask, 1mL of a 1-pentanol solution of 3-methylbenzyl alcohol (0.1M) was added, and 0.1mmol of K was added₂CO₃After sealing, the glass reactor is placed in a xenon lamp light source (400-^-2) The reaction is carried out for 12 hours at the temperature of 40 ℃. After the reaction, the reaction solution was filtered through an organic filter having a pore size of 0.22 μm to obtain a solution containing the product, and the reaction conversion rate was 93% and the selectivity of 3-methylbenzoate was 99% by GC quantitative analysis. (FIG. 6: as shown in FIG. 6, the liquid phase product after filtration was analyzed by gas chromatography to find that the main products were 3-methylbenzaldehyde and 3-methylbenzoic acid pentyl ester, and a trace of 3-methylbenzyl alcohol residue was detected-conversion rate ═ 3-methylbenzyl alcohol initial concentration after reaction-3-methylbenzyl alcohol concentration)/3-methylbenzyl alcohol initial concentration, selectivity ═ 3-methylbenzoic acid pentyl ester concentration/(3-methylbenzoic acid pentyl ester concentration + 3-methylbenzaldehyde concentration), 3-methylbenzyl alcohol, 3-methylbenzoic acid pentyl ester, 3-methylbenzoic acid concentration were each calibrated by the external standard method.)

Example 4:

Al₂O₃AgCo-loaded_0.8Alloy preparation and application:

weighing 0.5gAl₂O₃50mL of ethylene glycol was added and dispersed by sonication for 20 min. Adding 12.9mL AgNO while stirring at high speed₃Ethylene glycol solution (10mM), 10.3mL Co (NO)₃)₂Ethylene glycol solution (10mM) was stirred for 100min, added to 100mL hydrazine hydrate solution (10M) at 1mL/min at room temperature, and stirred for 1h to react thoroughly, and then the stirring was stopped. Standing and aging the suspension for 2 hours at room temperature, filtering with rapid filter paper to obtain a solid, washing with deionized water twice, washing with ethanol twice, vacuum drying at 60 ℃ for 24 hours to obtain AgCo with the alloy loading of about 4% relative to the carrier mass_0.8/Al₂O₃A catalyst. (FIG. 4): as shown in FIG. 4, AgCo_0.8The nano particles are uniformly dispersed in the gamma-Al₂O₃Surface of carrier, AgCo_0.8The alloy nanoparticles have a size of about 3-11 nm. )

Weighing 10mg of dried AgCo_0.8/Al₂O₃Adding catalyst into glass reaction bottle, adding 4mL of 1-butanol solution (0.1M) of 2-phenethyl alcohol, adding 0.4mmol K₂PO₄Sealing, placing the glass reactor in an LED light source (420 + -10 nm, 0.4W cm)^-2) The reaction is carried out for 40h at the temperature of 60 ℃. After the reaction, the reaction solution was filtered through an organic filter membrane having a pore size of 0.22 μm to obtain a solution containing the product, and the reaction conversion rate was 97% and the selectivity of butylacetate was 98% by quantitative analysis by GC.

Example 5:

preparation and application of ZSM-5 zeolite loaded CuNi alloy:

0.2g of ZrO was weighed₂10mL of deionized water was added and the mixture was ultrasonically dispersed for 20 min. 16.6mL Cu (NO) was added with high speed stirring₃)₂Aqueous solution (10mM), 16.6mL Ni (NO)₃)₂Aqueous solution (10mM), stirred for 30min, and then 5mL NaBH 5mL/min was added dropwise at room temperature₄The aqueous solution (0.35M) was stirred at room temperature for 1 hour and then the stirring was stopped. And standing and aging the suspension for 2 hours at room temperature, filtering by using quick filter paper to obtain a solid matter, washing twice by using deionized water and twice by using ethanol, and putting the solid matter into a vacuum chamber at 60 ℃ for drying for 24 hours to obtain the CuNi/ZSM-5 catalyst with the alloy loading amount of about 10 percent relative to the mass of the carrier. Weighing 50mg of dried CuNi/ZSM-5 catalyst, adding into a glass reaction bottle, adding 2mL of 4-ethynyl benzyl alcohol isopropanol solution (0.1M), adding 0.2mmol of NaOH, sealing, and placing the glass reactor in an LED light source (585 + -10 nm, 1.0W cm)^-2) The reaction is carried out for 20h at the temperature of 50 ℃. After the reaction, the reaction solution was filtered through an organic filter membrane having a pore size of 0.22 μm to obtain a solution containing the product, and the reaction conversion was 90% and the selectivity for tert-butyl 4-ethynylbenzoate was 96% by quantitative analysis by GC.