CN114618486A

CN114618486A - Platinum-palladium-silver compound catalyst, and preparation method and application thereof

Info

Publication number: CN114618486A
Application number: CN202011459307.XA
Authority: CN
Inventors: 王树东; 苏宏久; 周俊宏; 李大卫; 杨晓野; 严华
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2022-06-14
Anticipated expiration: 2040-12-11
Also published as: CN114618486B

Abstract

The invention discloses a catalyst which takes platinum-palladium-silver three-metal compound structure particles as active components and is loaded on micron silicon oxide spheres, and a preparation method and application thereof. The support comprises silica; the active component comprises an active element; the active elements comprise platinum, palladium and silver, and form a compound structure, wherein the content of platinum is 0.1-0.5 wt%, the content of palladium is 0.02-0.3 wt%, and the content of silver is 0.05-0.5 wt%. The trimetal composite catalyst has good activity and low loading capacity, greatly reduces the utilization rate of noble metal, has high catalytic efficiency and good selectivity, and greatly reduces the production cost after the catalyst is applied; the platinum-silver element in the catalyst is of an alloy structure, the platinum-silver alloy and palladium form a heterojunction structure, the dispersed nano particles are 1-10nm, the interaction with a silicon oxide carrier is strong, and the noble metal is not easy to fall off. The method is applied to the process for preparing hydrogen peroxide by anthraquinone hydrogenation and has good application prospect.

Description

Platinum-palladium-silver compound catalyst, and preparation method and application thereof

Technical Field

The application relates to a platinum-palladium-silver compound catalyst, a preparation method and application thereof, and belongs to the field of chemical catalytic materials.

Background

The hydrogen peroxide is an important chemical product, and because the oxygen generated after the hydrogen peroxide is decomposed has multiple effects of bleaching, oxidizing, disinfecting, sterilizing and the like, and has the characteristics of no by-product, no need of special treatment and the like, the hydrogen peroxide is widely used in industrial and agricultural production of papermaking, textile, chemical industry and the like. The hydrogen peroxide is mainly used in three application fields of papermaking, spinning and chemical synthesis. In the paper making industry, the bleaching technology is changed from chlorine bleaching to hydrogen peroxide bleaching, particularly, along with the supply shortage of newsprint products, the consumption of hydrogen peroxide in the paper making industry is increased rapidly in many aspects of forest paper integrated pulping and waste paper regeneration deinking projects; in the textile industry, in order to meet the requirements of the international market on the quality of textiles, outlet products are bleached by hydrogen peroxide, so that the consumption of the hydrogen peroxide in the textile industry is greatly increased; in the chemical industry, the application field of hydrogen peroxide is continuously widened, the demand gap of high-purity hydrogen peroxide, food-grade hydrogen peroxide and international markets for downstream products of hydrogen peroxide is continuously enlarged, and the consumption of hydrogen peroxide in the fields is increased by 30 percent; because the hydrogen peroxide has the characteristic of almost no pollution, the hydrogen peroxide is called as the cleanest chemical product and is the most representative reagent of green chemistry, and in recent years, the application market field is continuously expanded, and new application is continuously developed besides three main application fields. The anthraquinone process is the most mature and mainstream process for producing hydrogen peroxide at present. The technological process of anthraquinone process mainly includes four processes of hydrogenation, oxidation, extraction and post-treatment, in which the hydrogenation process is the core of whole process. Commercial hydrogenation catalysts used 0.3% Pd/Al₂O₃The method has the defects of poor hydrogenation selectivity, low hydrogenation efficiency and the like of the catalyst. The development of a low-cost and high-selectivity hydrogenation catalyst for synthesizing high-concentration hydrogen peroxide is one of the key technologies and technical development trends for realizing low-cost and high-efficiency hydrogen peroxide production by an anthraquinone method at present.

Disclosure of Invention

According to one aspect of the application, the platinum-palladium-silver composite catalyst is provided, the catalyst adopts a composite structure that platinum-silver alloy and palladium form heterojunction particles, active component silver atoms are dispersed, and platinum and palladium electronic structures are adjusted, so that the selectivity of the catalyst can be improved, the production efficiency can be improved, the palladium-platinum elements synergistically promote the activity of the catalyst, and the usage amount of platinum group noble metals is reduced; heterojunction particles formed by the platinum-silver alloy and palladium in the catalyst are in a highly dispersed nano state, and have strong interaction with a carrier, so that good stability can be maintained.

According to one aspect of the present application, there is provided a platinum-palladium-silver composite catalyst characterized by comprising a carrier and an active component supported on the carrier;

the support comprises silica;

the active component comprises an active element;

the active elements comprise three elements of platinum, palladium and silver.

In the application, on one hand, the carrier used by the catalyst is modified, and the selectivity of the catalyst is changed by adjusting the pore structure, the specific surface area and the like of the carrier, so that the catalyst can be operated at higher conversion rate. On the other hand, by adjusting the active components, the three elements act synergistically, so that the use amount of platinum group elements can be reduced greatly, the use amount of more expensive noble metal Pd is reduced greatly, and the catalyst has better catalytic activity and selectivity.

Optionally, the mass percentage of the platinum in the catalyst is 0.1-0.5 wt%;

preferably, the mass percentage of the platinum in the catalyst is 0.15-0.3 wt%;

optionally, the mass percentage of the palladium in the catalyst is 0.02-0.3 wt%;

preferably, the mass percentage of the palladium in the catalyst is 0.05-0.2 wt%;

optionally, the mass percentage of the silver in the catalyst is 0.05-0.5 wt%;

preferably, the mass percentage of the silver in the catalyst is 0.1-0.4 wt%;

the mass of silver is measured as the mass of silver element, the mass of palladium is measured as the mass of palladium element, and the mass of platinum is measured as the mass of platinum element.

Optionally, the upper limit of the mass percent content of the palladium in the catalyst is selected from 0.15 wt%, 0.20 wt%, 0.25 wt%, or 0.3 wt%; the lower limit is selected from 0.02 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, or 0.2 wt%.

Optionally, the upper limit of the mass percent content of platinum in the catalyst is selected from 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt%, or 0.5 wt%; the lower limit is selected from 0.1 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, or 0.4 wt%.

Optionally, the upper limit of the mass percent content of the silver in the catalyst is selected from 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt%, or 0.5 wt%; the lower limit is selected from 0.1 wt%, 0.15 wt%, or 0.2 wt%.

Optionally, the carrier is spherical silica containing mesopores;

the pore diameter of the carrier is 2-50 nm.

Optionally, the pore diameter of the carrier is 15-40 nm.

Optionally, the specific surface area of the carrier is 50-450 m²/g。

Optionally, the specific surface area of the carrier is 200-450 m²/g。

Optionally, the specific surface area of the carrier is 100-350 m²/g。

Optionally, the pore volume of the carrier is 0.3-1.8 cc/g.

Optionally, the pore volume of the carrier is 0.5-1.2 cc/g.

Optionally, the carrier has a pore volume of 0.5 to 1.5 ml/g.

Optionally, the bulk density of the carrier is 0.2-1.2 g/ml.

Optionally, the bulk density of the carrier is 0.5-0.9 g/ml.

Optionally, the bulk density of the carrier is 0.3-1.0 g/ml.

Optionally, the bulk density of the carrier is 0.6-1.0 g/ml.

Optionally, the active component is a platinum-palladium-silver complex structure;

the platinum-palladium-silver composite structure is characterized in that platinum and silver elements are of an alloy structure, palladium and platinum and silver are synthesized to form nano heterojunction particles which are dispersed on the carrier, and the particle size of the active component is 1-15 nm.

Optionally, the particle size of the active component is 1.5-5 nm.

Optionally, the active component is platinum-silver alloy and palladium to form heterojunction particles;

the platinum-silver alloy and palladium form heterojunction particles which are dispersed on the carrier in a nano shape, and the particle size of the active component is 0.5-10.0 nm.

Optionally, the particle size of the heterojunction particles formed by the platinum-silver alloy and the palladium is 1.5-3.5 nm.

Optionally, the particle size of the heterojunction particles formed by the platinum-silver alloy and the palladium is 1.0-5.0 nm.

Optionally, the particle size of the heterojunction particles formed by the platinum-silver alloy and the palladium is 0.50-3.21 nm.

According to one aspect of the present application, there is provided a method for preparing the above platinum-palladium-silver composite catalyst, characterized by comprising at least the steps of:

a1) obtaining a mixed precursor solution containing a platinum precursor, a palladium precursor and a silver precursor, and soaking a silicon oxide carrier in the mixed precursor solution to obtain a catalyst precursor; or

a2) Respectively obtaining a solution containing a platinum precursor and a solution containing a silver precursor, soaking a carrier in the solution containing the platinum precursor and the silver precursor for treatment, drying or roasting and washing, and then soaking the obtained solid in the solution containing the palladium precursor to obtain a catalyst precursor; or alternatively

a3) Obtaining a solution containing a platinum precursor, soaking a carrier in the solution containing the platinum precursor for treatment, drying or roasting and washing, and then soaking the obtained solid in the solution containing the palladium precursor and the solution containing the silver precursor to obtain a catalyst precursor; or

a4) Obtaining a solution containing a silver precursor, soaking a carrier in the solution containing the silver precursor for treatment, drying or roasting and washing, and soaking the obtained solid in the solution containing the palladium precursor and the solution containing the platinum precursor to obtain a catalyst precursor;

b) and (3) carrying out reduction treatment on the catalyst precursor obtained in a1), a2), a4) or a4) to obtain the platinum-palladium-silver composite catalyst.

Specifically, in the present application, the catalyst precursor is obtained by two methods, i.e., co-impregnation and stepwise impregnation. In the co-impregnation method, a mixed solution containing both a palladium precursor and a platinum precursor and a silver precursor is first prepared, and then the carrier is impregnated in the mixed solution. In the stepwise impregnation method, the support is first treated by being impregnated in a solution containing a precursor of platinum or silver to obtain a semi-dry solid, and then the semi-dry solid is impregnated in a solution containing a precursor of palladium or platinum or silver.

The palladium precursor comprises a palladium halogen complex and a palladium ammonia complex;

preferably, the palladium chloride complex comprises an inorganic ammonia complex;

preferably, the palladium precursor complex is selected from at least one of palladium dichlorodiammine, palladium dinitrodiammine, palladium tetraammine nitrate and palladium tetraammine chloride;

the platinum precursor comprises a platinum halogen complex and a platinum ammonia complex;

preferably, the platinum chloride complex comprises an inorganic ammoplatin complex;

preferably, the platinum precursor complex is selected from at least one of diammineplatinum dichloride, dinitrodiammineplatinum, tetrachlorodiammineplatinum and tetraamineplatinum dichloride;

the silver precursor is a silver diammine nitrate complex;

optionally, the mass percentage concentration of palladium, platinum and silver in the mixed solution is 0.1-0.8 wt%;

wherein, the content of palladium in the mixed solution is calculated by the content of palladium element; the content of platinum in the mixed solution is calculated by the content of platinum element; the content of silver in the mixed solution is calculated as the content of silver element.

The palladium complex is obtained by mixing a solution containing a palladium source with ammonia water;

preferably, the palladium source is a soluble palladium salt;

preferably, the soluble palladium salt is selected from at least one of inorganic acid salts of palladium;

preferably, the soluble palladium salt is selected from at least one of ammonium tetrachloropalladate, palladium nitrate, palladium chloride and ammonium hexachloropalladate;

the platinum-ammonia complex is obtained by mixing salts containing a palladium source with ammonia water;

preferably, the platinum source is a soluble palladium salt;

preferably, the soluble platinum salt is selected from at least one of inorganic acid salts of palladium;

preferably, the soluble palladium salt is selected from at least one of potassium tetrachloroplatinate, potassium hexachloroplatinate and platinum dichloride;

the silver-ammonia complex is obtained by mixing salts containing a silver source and ammonia water;

preferably, the silver source is selected from at least one of inorganic acid salts of silver;

preferably, the silver source is selected from at least one of silver nitrate, silver oxide, silver chloride.

Specifically, a solution containing a palladium source is mixed with aqueous ammonia under heating to obtain a solution containing a palladium-ammonia complex.

Specifically, a solution containing a platinum source is mixed with aqueous ammonia under heating to obtain a solution containing a platinum-ammonia complex.

Specifically, a salt containing a silver source and ammonia water are mixed under heating to obtain a solution containing a platinum-ammonia complex.

Optionally, the mass concentration of the ammonia water is 25-28 wt%.

Optionally, the ammonia water is concentrated ammonia water, and the mass concentration is 25-28 wt%.

Optionally, the pH of the ammonia water for mixing the palladium-ammonia complex solution, the platinum-ammonia complex solution and the silver-ammonia complex solution is 10-13.

Optionally, the pH of the aqueous ammonia is 10, 11, 12, 13.

Optionally, a2) is: mixing the obtained solution containing the platinum-ammonia complex and the silver-ammonia complex with ammonia water, soaking the carrier in the solution, mixing, stirring, filtering, washing, drying and roasting to obtain a solid;

and mixing the obtained solution containing the palladium-ammonia complex with ammonia water, adding the obtained solid into the solution, mixing, stirring, filtering and washing to obtain the catalyst precursor.

Optionally, a3) is: mixing the obtained solution containing the platinum-ammonia complex with ammonia water, soaking the carrier in the solution, mixing, stirring, filtering, washing, drying and roasting to obtain a solid;

and mixing the obtained solution containing the palladium-ammonia complex and the silver-ammonia complex with ammonia water, adding the obtained solid into the solution, mixing, stirring, filtering and washing to obtain the catalyst precursor.

Optionally, a4) is: mixing the obtained solution containing the silver-ammonia complex with ammonia water, soaking the carrier in the solution, mixing, stirring, filtering, washing, drying and roasting to obtain a solid;

Optionally, the drying condition is 100-140 ℃ and is not less than 3 h.

Alternatively, the drying conditions are 120 ℃ for 4 h.

Optionally, the vector in step a1) and step a2), step a3) and step a4) is prepared by the following method:

1) mixing raw materials containing silicon dioxide powder, silica sol, acid, a dispersing agent and organic amine to obtain mixed slurry;

2) molding the mixed slurry obtained in the step 1) in a high-temperature oil column through a jet flow generator, and then aging and roasting to obtain micron spherical silicon dioxide, namely the carrier.

Optionally, the raw material in step 1) further comprises an additive.

Optionally, the additive is selected from at least one of wollastonite, kaolin, silicon carbide fiber, glass fiber and talcum powder.

Optionally, in the step 1), the mass percentage of the silicon dioxide powder in the mixed slurry is 10-30%.

Optionally, the mass percentage of the silica sol in the mixed slurry is 60-80%.

Optionally, the addition amount of the dispersing agent is SiO in the mixed slurry₂0.1 to 5% by mass.

Optionally, the additive is added in an amount of SiO in the mixed slurry₂0.1 to 5% by mass.

Optionally, SiO in the mixed slurry₂The molar ratio of the organic amine to the organic amine is 1: 0.05-0.2.

Optionally, the molar ratio of the acid to the organic amine is 1: 1-3.

Optionally, in the step 1), the particle size of the silicon dioxide powder is 0.1-2 μm;

optionally, SiO in the silica sol₂20-40% of SiO in silica sol₂The particle size of the (B) is 2-50 nm.

Optionally, the acid is selected from at least one of organic acid and inorganic acid.

Optionally, the organic acid comprises at least one of salicylic acid, acetic acid, oxalic acid, citric acid.

Optionally, the inorganic acid comprises at least one of hydrochloric acid, nitric acid, phosphoric acid.

Optionally, the dispersant is selected from at least one of methanol, ethanol, isopropanol, amine acetate, ammonium citrate, polyethylene glycol, and polymaleic acid.

Optionally, the organic amine is selected from at least one of ethylenediamine, ethanolamine, triethylenediamine, diethylenetriamine, and hexamethylenetetramine.

Optionally, in step 2), the oil in the oil column is selected from vacuum pump oil, transformer oil, paraffin oil, solvent oil, vegetable oil, C-containing oil₁₀～C₁₃At least one mineral oil mixed with linear paraffin.

Optionally, the temperature of the oil column is 80-150 ℃.

Optionally, the aperture of the nozzle of the jet generator is 0.1-1.0 mm; the jet flow speed is 1-20 m/s.

Optionally, in the step 2), the aging time is 3-24 hours.

Optionally, the roasting temperature is 500-700 ℃, and the roasting time is 10-24 h.

Optionally, the baking atmosphere in the step a1), the step a2), the step a3) and the step a4) is at least one selected from oxygen and inert gas;

preferably, the inert gas in the roasting atmosphere is nitrogen or argon, and the volume percentage content of oxygen is 1-60%.

The roasting treatment conditions are as follows: the roasting temperature is 150-900 ℃, and the roasting time is 1-12 h;

the detergent is selected from an aqueous solution or an alcohol solution;

preferably, the detergent is at least one selected from ammonia water, sodium bicarbonate solution, ethanol, propanol and isopropanol;

optionally, in the step b), the reducing atmosphere is selected from hydrogen or a mixed gas of hydrogen and an inert gas.

Optionally, the inert gas is selected from at least one of inert gases.

Optionally, the inert gas is selected from at least one of nitrogen and argon.

Optionally, the reducing atmosphere is a mixed atmosphere of hydrogen and nitrogen, and the volume percentage of hydrogen in the mixed atmosphere is 5-90%.

Optionally, the reduction treatment conditions: the reduction temperature is 250-800 ℃, and the reduction time is 0.5-12.0 h.

Optionally, the reduction treatment conditions: the reduction temperature is 50-600 ℃, and the reduction time is 1-6 h.

Optionally, the reduction treatment conditions: the reduction temperature is 50-500 ℃, and the reduction time is 0.5-10 h.

Optionally, the reduction treatment conditions: the reduction temperature is 300-500 ℃, and the reduction time is 0.5-2 h.

Optionally, the reduction treatment conditions: the reduction temperature is 50-400 ℃, and the reduction time is 0.5-6 h.

Optionally, the reduction treatment conditions: the reduction temperature is 100-350 ℃, and the reduction time is 2-6 h.

Optionally, the upper limit of the reduction temperature is selected from 100 ℃, 150 ℃, 200 ℃, 300 ℃, 350 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃ or 800 ℃; the lower limit is selected from 50 deg.C, 100 deg.C, 150 deg.C, 200 deg.C, 300 deg.C, 350 deg.C, 400 deg.C, 500 deg.C, 600 deg.C or 700 deg.C.

Optionally, the upper limit of the reduction time is 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10 h; the lower limit is 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h or 9 h.

According to another aspect of the application, the application of the platinum-palladium-silver compound catalyst prepared by any one of the catalysts and the method in the preparation of hydrogen peroxide by anthraquinone hydrogenation is provided.

Optionally, the anthraquinone is selected from at least one of 2-ethyl anthraquinone, 2-amyl anthraquinone, 2-tert-butyl anthraquinone.

Optionally, the reaction conditions are: the reaction temperature is 30-60 ℃; the reaction pressure is 0.01-3.0 Mpa; 7-350mL/min of hydrogen and 20-200h of liquid space velocity^-1。

Alternatively, the reaction conditions are: the reaction temperature is 30-50 ℃; the reaction pressure is 0.03-0.3 Mpa; 7-90mL/min of hydrogen and 40-100h of liquid space velocity^-1。

Alternatively, the reaction conditions are: the reaction temperature is 40 ℃; the reaction pressure is 0.1 Mpa; 70mL/min of hydrogen and 50-80h of liquid space velocity^-1。

Optionally, the anthraquinone is selected from 2-ethyl anthraquinone, and anthraquinone hydrogenation reaction is carried out at the temperature of 30-60 ℃.

In the hydrogenation process of hydrogen peroxide produced by the anthraquinone method, the main reaction is the hydrogenation reaction of carbonyl and carbon-carbon double bonds on a benzene ring, and according to the reaction characteristics, the hydrogenation reaction of the carbon-carbon double bonds on the benzene ring is limited in order to improve the selectivity of the catalyst, so that the degree of deep hydrogenation side reaction is reduced. When palladium and platinum elements exist simultaneously, the adsorption capacity to hydrogen is larger than that of a single element, and the adsorption capacity to carbonyl is weaker than that of the platinum element, so that the mass fraction of the noble metal elements of the catalyst is greatly reduced, and the existence of the silver element can promote electrons to be transferred from palladium and platinum to silver, so that the adsorption of the palladium and platinum to the hydrogen is enhanced, the hydrogen activation capacity of an active center of the catalyst is improved, and the reaction activity is enhanced. The dissociated hydrogen atoms can overflow from the palladium-platinum active center to the silver and the carrier under the action of hydrogen overflow, so that the concentration of the hydrogen atoms in the palladium-platinum active center is kept not to be too high to aggravate side reaction, and high reaction selectivity is achieved. The catalyst cost is obviously reduced, and the catalyst has good popularization and application values.

In the hydrogenation process of producing hydrogen peroxide by the anthraquinone method, anthraquinone molecules are large and are limited in diffusion in the catalyst, so that excessive hydrogenation of anthraquinone can be caused to generate irreversible side reactions after the anthraquinone molecules are left on the catalyst for a long time, and the selectivity is reduced. Therefore, the pore structure of the catalyst carrier has a great influence on the performance of the catalyst. The silicon oxide has the properties of adjustable specific surface and pore volume, thereby playing an important role in the fields of catalysis and separation. The preparation of the silicon oxide with the specific aperture has very important significance for the selectivity of the anthraquinone hydrogenation process and the separation efficiency of separation and purification. The silica carrier with weak acidity is also beneficial to desorption of anthraquinone molecules after hydrogenation, thereby avoiding deep hydrogenation and being beneficial to improving selectivity. The active ingredient particles may also be dispersed and immobilized by virtue of the interaction formed between the active ingredient and the silica support.

The composition of the active components, the particle size and the degree of dispersion of the catalyst have a significant influence on the activity, selectivity and stability of the catalyst. One of the main methods to adjust the composition and particle size of the active component to increase the catalyst activity and selectivity. Active components used by the mainstream anthraquinone hydrogenation catalyst are palladium or bimetallic active components taking palladium as a main component, the requirements of high activity and high selectivity in high-concentration hydrogen peroxide production cannot be met simultaneously only by adjusting the dispersion degree of palladium, and the requirement of the catalyst for reducing the loading amount of noble metals cannot be met only by the synergistic action of palladium and a second metal element. The palladium platinum is used as a main active component and a third component is added, so that the noble metal load can be greatly reduced, the catalytic performance can be adjusted, and the catalyst cost is remarkably reduced.

The beneficial effects that this application can produce include:

(1) platinum palladium is used as a main active component, and the capacity of activating hydrogen is improved through the electronic effect and the geometric effect of the platinum palladium, so that the noble metal loading capacity of the catalyst is reduced, and particularly the quality of a more expensive palladium element is reduced;

(2) the addition of silver can better disperse and fix palladium and platinum elements, improve the utilization efficiency of platinum and palladium and improve the performance of the catalyst;

(3) the active metal heterojunction in the catalyst is in a highly dispersed nano state, and has stronger interaction with the carrier, so that better stability can be maintained.

Drawings

FIG. 1 is a graph showing the results of evaluation of the hydrogenation performance of sample No. 1;

FIG. 2 is a graph showing the results of evaluation of the hydrogenation performance of sample No. 2;

FIG. 3 is a graph showing the results of evaluation of the hydrogenation performance of sample No. 3;

FIG. 4 is a graph showing the results of evaluation of the hydrogenation performance of sample No. 4;

FIG. 5 is a graph showing the results of evaluation of the hydrogenation performance of sample No. 5;

FIG. 6 is a graph showing the results of evaluation of the hydrogenation performance of sample No. 6.

Fig. 7 is a TEM photograph of sample # 1 catalyst.

FIG. 8 is a statistical plot of the pore size distribution of the support of sample # 1.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.

In accordance with one embodiment of the present application,

1. a platinum-palladium-silver catalyst for preparing hydrogen peroxide by anthraquinone hydrogenation uses mesoporous silicon dioxide as a carrier, and the catalyst uses Pt_xPd_yAg_1-x-y/SiO₂The catalyst is prepared by adopting an impregnation method, is prepared by washing, drying and reducing, is subjected to a 2-ethyl anthraquinone hydrogenation activity test at the reaction temperature of 30-60 ℃, and loads active components of platinum, palladium and silver, wherein the content of platinum in the catalyst is 0.1-0.5 wt%, the content of palladium in the catalyst is 0.02-0.3 wt%, and the content of silver in the catalyst is 0.05-0.5 wt%

2. The carrier is formed mesoporous silica, the carrier is spherical, and the aperture of catalyst particles is 2-50 nm.

3. The specific surface area of the carrier is 100-350 m²(iii) a pore volume of 0.5 to 1.5ml/g and a bulk density of 0.6 to 1.0 g/ml.

4. A hydrogen reduction method is adopted.

5. Firstly, preparing an acidic platinum-palladium-silver solution or salt into an ammonia complex precursor, dipping the precursor solutions of the three metals on a silicon oxide carrier together or step by step, and then washing, drying, reducing and the like to obtain the catalyst in the atmosphere of hydrogen balanced by inert gases such as nitrogen or argon.

6. The palladium source used for preparing the platinum-palladium-silver catalyst is tetrachloro ammonium palladate or palladium nitrate, palladium chloride and hexachloro ammonium palladate, the platinum source is tetrachloro platinic acid, platinum nitrate, hexachloro platinic acid and hexachloro sodium platinate, the silver source is selected from silver nitrate or silver oxide and silver chloride, and the concentration of the platinum source, the palladium source and the silver source is generally 200-5000 ppm.

7. The prepared platinum-palladium-silver catalyst is highly dispersed on a silicon oxide carrier in a nano shape, and the nano particle size of metal particles is 1.0-5.0 nm.

Example 1

(1-1) weighing SiO with an average particle size of 2 μm₂21g of powder, 15ml of concentrated hydrochloric acid and SiO₂Is a 30% wt alkaline silica sol 126g (wherein SiO is₂The average particle size of 25nm) and 10ml of methanol, adding 15g of hexamethylenetetramine, and fully dissolving to obtain mixed slurry;

(1-2) selecting a nozzle with the aperture of 0.25mm, installing the nozzle on a jet flow generator, injecting the mixed slurry obtained in the step (1-1) into 25# transformer oil at the temperature of 95 ℃ at the speed of 5m/s for forming, standing and aging for 4 hours, separating the formed pellets from the oil, and drying in vacuum at the temperature of 80 ℃ for 12 hours. Washing the obtained product to be neutral, then drying the product for 10 hours at 140 ℃, and roasting the product for 12 hours at 550 ℃ to obtain micron spherical silicon oxide particles, namely carriers;

(1-3) weighing 3.3600g of PdCl₂(palladium content: 59.5%) was dissolved in 20ml of deionized water to prepare a solution, and the solution was heated to slightly boiling and then added to PdCl₂Dripping 1ml of 25% ammonia water into the solution until the precipitate is generated and then completely dissolved to obtain a palladium dichlorotetrammine solution, and metering the volume to 100.00ml to obtain a solution containing the palladium-ammonia complex;

(1-4) weigh 5.00g K₂PtCl₄(platinum content 47.0%), 2.5mL concentrated HCl in 75mL water. The solution was taken out of a 150mL beaker, 4g of ammonium chloride was dissolved, and about 10mL of 3mol/L NH was carefully added₃·H₂O until neutral, then 6.75mL of 3mol/L NH₃·H₂And O, putting the solution into a refrigerator, placing the solution until a green-yellow solid precipitate is completely generated, changing the supernatant from dark red to light yellow (24-48 h), carrying out suction filtration on the precipitate, and washing the precipitate with ice water for several times (10 mL each time). Transferring the precipitate to a 250mL triangular flask, adding 1mol/L HCl to ensure that the volume is 150mL, heating the mixture to boil, and cooling and fixing the volume to 200mL to obtain a solution containing the platinum-ammonia complex;

(1-5) weighing 2.00g AgNO₃(silver content: 63.5%) was dissolved in 20ml of deionized water to prepare a solution, and the solution was heated to slightly boiling and then added to AgNO₃Dropwise adding 2ml of 25% ammonia water into the solution until the precipitate is generated and is completely dissolved, and fixing the volume to 100.00ml to obtain a solution containing a silver-ammonia complex;

(1-6) transferring 512. mu.L of a solution containing platinum-ammonia complex and 472. mu.L of a solution containing silver-ammonia complex to 149.0mL of aqueous ammonia having a pH of 12, adding 6g of the spherical silica particles prepared in step (1-2), mixing, stirring sufficiently at 60 ℃ for 3.0 hours, filtering the mixture, washing with deionized water, and drying at 120 ℃ for 2 hours to obtain a solid;

(1-7) placing the solid in (1-6) in a tube furnace in O₂And N₂Mixed gas (O)₂Roasting at 400 ℃ for 4h in the atmosphere of 10% by volume in the mixed gas, cooling, taking out, washing with deionized water, and drying at 120 ℃ for 2h to obtain a solid;

(1-8) transferring 300. mu.L of a solution containing a palladium-ammonia complex to 149.7mL of an aqueous ammonia solution having a pH of 12, adding the calcined solid prepared in the step (1-7), mixing, sufficiently stirring at 60 ℃ for 3.0 hours, filtering, washing with deionized water, and drying at 120 ℃ for 2 hours to obtain a catalyst precursor;

(1-9) placing the catalyst precursor in a tube furnace in H₂And N₂Mixed gas (H)₂The volume percentage of the catalyst in the mixed gas is 10%), reducing the catalyst for 3 hours at 400 ℃ to obtain the palladium-platinum-silver composite catalyst which is marked as sample No. 1;

in sample # 1, the mass percent of palladium in the sample was 0.1 wt%, the mass percent of platinum in the sample was 0.1 wt%, and the mass percent of silver in the sample was 0.1 wt%.

Example 2

(2-1) weighing SiO with an average particle size of 2 μm₂21g of powder, 5ml of concentrated nitric acid and SiO₂Is a 30% wt alkaline silica sol 126g (wherein SiO is present)₂The average particle size of 25nm) and 10ml of ethanol, adding 2g (300 meshes) of wollastonite and 15g of hexamethylenetetramine, and fully dissolving to obtain mixed slurry;

(2-2) selecting a nozzle with the aperture of 0.25mm, installing the nozzle on a jet flow generator, injecting the mixed slurry obtained in the step (2-1) into 25# transformer oil at the temperature of 90 ℃ at the speed of 5m/s for forming, standing and aging for 4 hours, separating the formed small balls from the oil, and drying in vacuum at the temperature of 60 ℃ for 24 hours. Washing the obtained product to be neutral, then drying the product for 10 hours at 140 ℃, and roasting the product for 12 hours at 550 ℃ to obtain micron spherical silicon oxide particles, namely carriers;

(2-3) weighing 2.1657g Pd (NO)₃)₂(palladium content: 46.2%) was dissolved in 10ml of deionized water to prepare a solution, and the solution was heated to slightly boiling condition, followed by addition of Pd (NO)₃)₂Dropwise adding 1ml of 28% ammonia water into the solution until the precipitate is generated and then completely dissolved to obtain a light green transparent tetraamminepalladium nitrate solution, and fixing the volume to 50.00ml to obtain a solution containing the palladium-ammonia complex;

(2-4) weighing 2gK₂PtCl₆(the platinum content is 46.2%) is added into 100mL of water, 20g of sodium nitrite is added for reaction, the mixture is stirred and heated, the solution becomes transparent and turns into pale green yellow, the solution is cooled after no gas is generated, 12mL of 20% ammonia water solution is added and slowly boiled, the volume is fixed to 200mL after cooling, and the solution containing the platinum-ammonia complex is obtained;

(2-5) weighing 4.00g AgNO₃(silver content: 63.5%) was dissolved in 20ml of deionized water to prepare a solution, and the solution was heated to slightly boiling and then added to AgNO₃5ml of 10% ammonia water is dripped into the solution until the precipitate is generated and then is completely dissolved, and the volume is determined to be 200.00ml, thus obtaining the solution containing the silver-ammonia complex;

(2-6) transferring 2600 μ L of the solution containing platinum-ammonia complex and 236 μ L of the solution containing silver-ammonia complex to 147.1mL of an aqueous ammonia solution having a pH of 12, adding 6g of the spherical silica particles prepared in step (2-2), mixing, sufficiently stirring at 60 ℃ for 3.0 hours, filtering the mixed solution, washing with deionized water, and drying at 120 ℃ for 2 hours to obtain a solid;

(2-7) placing the solid in (2-6) in a tube furnace in O₂And N₂Mixed gas (O)₂50 percent of the mixed gas) at 500 ℃ for 4h, cooling, taking out, washing with ethanol, and drying at 120 ℃ for 2h to obtain a solid;

(2-8) transferring 300. mu.L of a solution containing a palladium-ammonia complex to 149.7mL of an aqueous ammonia solution having a pH of 12, adding the dried solid prepared in the step (2-7), mixing, sufficiently stirring at 30 ℃ for 2.0 hours, filtering, washing with deionized water, oven-drying at 120 ℃ for 2 hours, and then calcining at 400 ℃ for 2 hours to obtain a catalyst precursor;

(2-9) placing the catalyst precursor in a tube furnace in H₂And N₂Mixed gas (H)₂5 percent of volume in the mixed gas) and reducing for 6h at 300 ℃ to obtain a platinum-palladium-silver composite catalyst which is marked as sample No. 2;

in sample 2#, the mass percent of palladium in the sample was 0.1 wt%, the mass percent of platinum in the sample was 0.2 wt%, and the mass percent of silver in the sample was 0.05 wt%.

Example 3

(3-1) weighing SiO with an average particle size of 2 μm₂31g of powder, 10ml of concentrated phosphoric acid and SiO₂Is a 30% wt alkaline silica sol 126g (wherein SiO is₂The average particle size of 25nm) and 8ml of polyethylene glycol, adding 2.5g (500 mesh) of silicon carbide fiber and 14g of hexamethylenetetramine, and fully dissolving to obtain mixed slurry;

(3-2) selecting a nozzle with the aperture of 0.35mm, installing the nozzle on a jet flow generator, injecting the mixed slurry obtained in the step (3-1) into 25# transformer oil at the temperature of 90 ℃ at the speed of 5m/s for forming, standing and aging for 5 hours, separating the formed small balls from the oil, and drying in vacuum at the temperature of 80 ℃ for 16 hours. The obtained product is washed to be neutral, then dried for 10 hours at 140 ℃, and roasted for 12 hours at 550 ℃ to obtain micron spherical silicon oxide particles, namely the carrier.

(3-3) weighing 1.6800g of PdCl₂(palladium content: 59.5%) was dissolved in 10ml of deionized water to prepare a solution, and the solution was heated to slightly boiling and then added to PdCl₂1ml of 26 percent ammonia water is dripped into the solution until the precipitate is generated and then is completely dissolved to obtain a light green transparent palladium tetraammine dichloride solution, and the volume is constant to 50.00ml to obtain a solution containing palladium-ammonia complex;

(3-4) weighing 50mL of the solution in the step (1-4), heating the solution in a water bath to 75 ℃, keeping the temperature, stirring the solution by using a stirrer, slowly introducing chlorine gas, supplementing hot water during the period, keeping the temperature at 50mL, stopping introducing the chlorine gas after 3 hours, boiling and removing excessive chlorine, cooling the solution and fixing the volume to 200mL to obtain a solution containing the platinum-ammonia complex;

(3-5) 3.38g of AgCl (silver content 75.2%) was weighed into 20ml of deionized water, and 1g of NH was added simultaneously₄NO₃Heating to a slightly boiling condition, dropwise adding 5ml of 10% ammonia water into the mixture until the precipitate is completely dissolved, and metering the volume to 200.00ml to obtain a solution containing a silver-ammonia complex;

(3-6) transferring 750. mu.L of the solution containing palladium-ammonia complex, 512. mu.L of the solution containing silver-ammonia complex and 1310. mu.L of the solution containing platinum-ammonia complex to 147.5mL of aqueous ammonia solution having pH of 10 to obtain a mixed solution containing platinum, palladium and silver;

(3-7) weighing 6.0g of spherical silica particles prepared in the step (3-2), adding the spherical silica particles into the mixed solution containing platinum, palladium and silver in the step (3-6), mixing, fully stirring for 2.0 hours at 30 ℃, filtering, washing with deionized water, and drying for 2 hours at 120 ℃ to obtain a catalyst precursor;

(3-8) placing the catalyst precursor in a tube furnace in H₂And N₂Mixed gas (H)₂10% in the mixed gas), reducing for 2h at 350 ℃, washing with 1% ammonia water after cooling, and drying for 2h at 120 ℃ to obtain a platinum-palladium-silver composite catalyst which is marked as sample # 3;

in sample # 3, the mass percent of palladium in the sample was 0.25 wt%, the mass percent of platinum in the sample was 0.1 wt%, and the mass percent of silver in the sample was 0.1 wt%.

Example 4

(4-1) SiO having an average particle diameter of 2 μm₂21g of powder, 5ml of concentrated hydrochloric acid and SiO₂Is a 30% wt alkaline silica sol 126g (wherein SiO is present)₂Average particle size of 12nm) and 10ml of isopropyl alcohol were thoroughly mixed, 15g of hexamethylenetetramine was added thereto, and the mixture was thoroughly dissolved to obtain a mixed slurry.

(4-2) selecting a nozzle with the aperture of 0.2mm, installing the nozzle on a jet flow generator, injecting the mixed slurry obtained in the step (4-1) into 25# transformer oil at the temperature of 85 ℃ at the speed of 1m/s for forming, standing and aging for 7 hours, separating the formed small balls from the oil, and drying in vacuum at the temperature of 60 ℃ for 12 hours. The obtained product is washed to be neutral, then dried for 10 hours at 140 ℃, and roasted for 12 hours at 550 ℃ to obtain micron spherical silicon oxide particles, namely the carrier.

(4-3) weighing 2.1657g Pd (NO)₃)₂(palladium content: 46.2%) was dissolved in 10ml of deionized water to prepare a solution, and the solution was heated to slightly boiling condition, followed by addition of Pd (NO)₃)₂1ml of 10% ammonia water is dripped into the solution until the precipitate is generated and then is completely dissolved to obtain a tetraammine palladium nitrate solution, and the volume is determined to 50.00ml to obtain a solution containing the palladium-ammonia complex;

(4-4) weighing 1.00g of PtCl₂(platinum content: 73.6%) was dissolved in 10ml of deionized water to prepare a solution, and the solution was heated to slightly boiling, and then PtCl was added₂Dripping 1ml of 25% ammonia water into the solution until the precipitate is generated and then completely dissolved to obtain a light green transparent platinum tetraammine dichloride solution, and metering the volume to 50.00ml to obtain a solution containing a platinum-ammonia complex;

(4-5) 3.38g of AgCl (silver content 75.2%) was weighed into 20ml of deionized water, and 2g of NH was added simultaneously₄NO₃Heating to slightly boiling condition, dripping 5ml of 25% ammonia water into the mixture until the precipitate is completely dissolved, and metering the volume to 200.00ml to obtain a solution containing silver-ammonia complex;

(4-6) transferring 408. mu.L of the platinum-ammonia complex-containing solution to 149.6mL of an aqueous ammonia solution having a pH of 12, adding 6g of the spherical silica particles prepared in step (1-2), mixing, stirring thoroughly at 60 ℃ for 3.0 hours, filtering the mixture, washing with deionized water, and drying at 120 ℃ for 2 hours to obtain a solid;

(4-7) placing the solid in (4-6) in a tube furnace in O₂And N₂Mixed gas (O)₂80 percent of volume in the mixed gas) for 4 hours at 250 ℃, cooling, taking out, washing with 1 percent of sodium bicarbonate solution, and drying at 120 ℃ for 2 hours to obtain a solid;

(4-8) transferring 600 μ L of the solution containing the palladium-ammonia complex and 236 μ L of the solution containing the silver-ammonia complex to 149.1mL of an aqueous ammonia solution having a pH of 12, adding the dried solid prepared in the step (4-7), mixing, sufficiently stirring at 50 ℃ for 2.0 hours, filtering, washing with a 1% sodium bicarbonate solution, oven-drying at 120 ℃ for 2 hours, and then calcining at 400 ℃ for 2 hours to obtain a catalyst precursor;

(4-9) placing the catalyst precursor in a tube furnace in H₂And N₂Mixed gas (H)₂Reducing for 6h at 200 ℃ in the atmosphere of 10% by volume of the mixed gas to obtain a platinum-palladium-silver composite catalyst which is marked as # 4;

in sample # 4, the mass percent of palladium in the sample was 0.2 wt%, the mass percent of platinum in the sample was 0.1 wt%, and the mass percent of silver in the sample was 0.05 wt%.

Example 5

(5-1) SiO having an average particle diameter of 2 μm₂47.1g of powder, 15ml of concentrated hydrochloric acid and SiO₂Is a 30% wt alkaline silica sol 126g (wherein SiO is present)₂Average particle size of 12nm) and 5ml of ethanol were thoroughly mixed, and 14g of hexamethylenetetramine was added and sufficiently dissolved to obtain a mixed slurry.

(5-2) selecting a nozzle with the aperture of 1mm, installing the nozzle on a jet flow generator, injecting the mixed slurry obtained in the step (5-1) into 25# transformer oil at the temperature of 95 ℃ at the speed of 2m/s for forming, standing and aging for 10 hours, separating the formed pellets from the oil, and drying in vacuum at the temperature of 80 ℃ for 12 hours. The obtained product is washed to be neutral, then dried for 20 hours at 110 ℃, and roasted for 12 hours at 550 ℃ to obtain micron spherical silicon oxide particles, namely the carrier.

(5-3) weighing 1.6800g of PdCl₂(palladium content: 59.5%) was dissolved in 10ml of deionized water to prepare a solution, and the solution was heated to slightly boiling and then added to PdCl₂Dropwise adding 1ml of 27% ammonia water into the solution until the precipitate is generated and then completely dissolved to obtain a light green transparent palladium tetraammine dichloride solution, and fixing the volume to 50.00ml to obtain a solution containing the palladium-ammonia complex;

(5-4) weigh 5.00g K₂PtCl₄(platinum content 47.0%), 5mL of concentrated hydrochloric acid in 50mL of water. The solution was taken out of a 150mL beaker, 5g of ammonium chloride was dissolved, and about 10mL of 3mol/L NH was carefully added₃·H₂O until neutral, then 6.75mL of 3mol/L NH₃·H₂And O, putting the solution into a refrigerator, placing the solution until a green-yellow solid precipitate is completely generated, changing the supernatant from dark red to light yellow (24-48 h), carrying out suction filtration on the precipitate, and washing the precipitate with ice water for several times (20 mL each time). Transferring the precipitate to a 250mL triangular flask, adding 1mol/L HCl to ensure that the volume is 150mL, heating the mixture to boil, and cooling and fixing the volume to 200mL to obtain a solution containing the platinum-ammonia complex;

(5-5) weigh 2.73g of Ag₂O (silver content 93.1%) was added to 20ml of deionized water, and 2g of NH was added simultaneously₄NO₃Heating to slightly boiling condition, dripping 5ml of 25% ammonia water into the mixture until the precipitate is completely dissolved, and metering the volume to 200.00ml to obtain a solution containing silver-ammonia complex;

(5-6) transferring 1530. mu.L of the platinum-ammonia complex-containing solution to 148.5mL of an aqueous ammonia solution having a pH of 12, adding 6g of the spherical silica particles prepared in step (5-2), mixing, stirring thoroughly at 60 ℃ for 3.0 hours, filtering the mixture, washing with methanol, and drying at 120 ℃ for 2 hours to obtain a solid;

(5-7) placing the solid in (5-6) in a tube furnace in O₂And N₂Mixed gas (O)₂80 percent of the mixed gas) at 250 ℃ for 4h, cooling, taking out, washing with 1 percent of sodium bicarbonate solution, and drying at 120 ℃ for 2h to obtain a solid;

(5-8) transferring 1200 μ L of the solution containing the palladium-ammonia complex and 236 μ L of the solution containing the silver-ammonia complex to 148.5mL of an aqueous ammonia solution having a pH of 12, adding the dried solid prepared in the step (5-7), mixing, sufficiently stirring at 50 ℃ for 2.0 hours, filtering, washing with a 1% sodium bicarbonate solution, and oven-drying at 120 ℃ for 2 hours to obtain a catalyst precursor;

(5-9) placing the catalyst precursor in a tube furnace in H₂And N₂Mixed gas (H)₂The volume percentage of the platinum-palladium-silver catalyst in the mixed gas is 20 percent), and the platinum-palladium-silver catalyst is obtained by reducing for 2h at 400 ℃ and is marked as sample No. 5;

in sample # 5, the mass percent of palladium in the sample was 0.1 wt%, the mass percent of platinum in the sample was 0.3 wt%, and the mass percent of silver in the sample was 0.05 wt%.

Example 6

(6-1) SiO having an average particle diameter of 2 μm₂18.1g of powder, 15ml of concentrated hydrochloric acid and SiO₂Is a 30% wt alkaline silica sol 126g (wherein SiO is present)₂Average particle size of 12nm) and 10ml of ethanol were thoroughly mixed, and 14g of hexamethylenetetramine was added and sufficiently dissolved to obtain a mixed slurry.

(6-2) selecting a nozzle with the aperture of 0.3mm, installing the nozzle on a jet flow generator, injecting the mixed slurry obtained in the step (6-1) into 25# transformer oil at the temperature of 95 ℃ at the speed of 20m/s for forming, standing and aging for 12 hours, separating the formed small balls from the oil, and drying in vacuum at the temperature of 80 ℃ for 12 hours. The obtained product is washed to be neutral, then dried for 20 hours at 110 ℃, and roasted for 12 hours at 550 ℃ to obtain micron spherical silicon oxide particles, namely the carrier.

(6-3) weighing 2.1657g Pd (NO)₃)₂(palladium content: 46.2%) was dissolved in 10ml of deionized water to prepare a solution, and the solution was heated to slightly boiling condition, followed by addition of Pd (NO)₃)₂Dropwise adding 1ml of 25% ammonia water into the solution until the precipitate is generated and then completely dissolved to obtain a light green transparent tetraamminepalladium nitrate solution, and fixing the volume to 50.00ml to obtain a solution containing the palladium-ammonia complex;

(6-4) weighing 1.00g of PtCl₂(platinum content: 73.6%) was dissolved in 30ml of deionized water to prepare a solution, and the solution was heated to slightly boiling and then subjected to PtCl reaction₂Dripping 10ml of 5% ammonia water into the solution until the precipitate is generated and then completely dissolving to obtain a platinum tetraammine dichloride solution, and metering the volume to 100ml to obtain a solution containing a platinum-ammonia complex;

(6-5) weighing 2.73g of Ag₂O (silver content 93.1%) was added to 30ml of deionized water, and 0.5g of NH was added simultaneously₄NO₃Heating to a slightly boiling condition, then dropwise adding 20ml of 5% ammonia water into the mixture until the precipitate is generated and is completely dissolved, and fixing the volume to 200.00ml to obtain a solution containing a silver-ammonia complex;

(6-6) transferring 1888. mu.L of the silver-ammonia complex-containing solution to 148.2mL of an aqueous ammonia solution having a pH of 13, adding 6g of the spherical silica particles prepared in step (5-2), mixing, stirring thoroughly at 60 ℃ for 3.0 hours, filtering the mixture, washing with methanol, and drying at 120 ℃ for 2 hours to obtain a solid;

(6-7) placing the solid in (6-6) in a tube furnace in O₂And N₂Mixed gas (O)₂80 percent of the mixed gas) at 250 ℃ for 4 hours to obtain a solid;

(6-8) transferring 300. mu.L of a solution containing a palladium-ammonia complex and 1630. mu.L of a solution containing a platinum-ammonia complex to 148.0mL of an aqueous ammonia solution having a pH of 13, adding the dried solid obtained in the step (6-7), mixing, stirring thoroughly at 50 ℃ for 2.0 hours, filtering, washing with a 1% sodium bicarbonate solution, and oven-drying at 120 ℃ for 2 hours to obtain a catalyst precursor;

(6-9) placing the catalyst precursor in a tube furnace in H₂And N₂Mixed gas (H)₂The volume percentage of the platinum-palladium-silver composite catalyst in the mixed gas is 20 percent) and the reduction is carried out for 3 hours at 350 ℃ to obtain the platinum-palladium-silver composite catalyst which is marked as sample No. 6;

in sample 6#, the mass percent of palladium in the sample was 0.1 wt%, the mass percent of platinum in the sample was 0.2 wt%, and the mass percent of silver in the sample was 0.4 wt%.

Example 7

The evaluation of the catalyst is carried out in a high-pressure reaction kettle, and the method specifically comprises the following steps of preparing working solution (the mass content of 2-amylanthraquinone in the working solution is 170g/L) from heavy aromatic hydrocarbon, diisobutyl carbinol (the volume ratio is 3:2) and 2-amylanthraquinone, and respectively adding 0.7g of sample No. 1-6 catalyst and 120mL of the working solution into a 200mL high-pressure kettle, wherein the feeding speed of the working solution is 1.0mL/min, and the hydrogen flow is 15 mL/min. The temperature of the water bath is controlled to be 45 ℃, and the pressure is controlled to be about 0.1 MPa.

Oxidizing the hydrogenated liquid with oxygen, extracting with distilled water, and adding KMnO₄The hydrogen peroxide produced was measured by titration and the hydrogenation efficiency (hydrogen efficiency) was calculated. The hydrogenated liquid refers to the working liquid taken out from the reaction kettle after the hydrogenation reaction is finished.

Wherein:

b-hydrogenation efficiency (g/L);

C—KMnO₄concentration of the solution (mol/L);

V₀—KMnO₄volume of solution (mL);

M—H₂O₂molar mass (g/mol);

v is the volume (mol/L) of the hydrogenation solution.

The space-time yield STY of hydrogen peroxide is the yield of hydrogen peroxide per unit mass of palladium per unit time and is calculated according to the following formula:

wherein:

STY-Mass of Hydrogen peroxide produced per gram of platinum and Palladium per day (kg)_H2O2g^-1 _PtPdd^-1)；

B-hydrogenation efficiency of the catalyst (kg. L) calculated according to the above formula^-1)；

Q_LFlow Rate (L.d) of the anthraquinone working fluid^-1)；

m-the loading mass (g) of the catalyst;

θ_Pdcatalyst platinum and palladium content (wt%).

FIGS. 1 to 6 show the results of the evaluation of the hydrogenation performance of the catalysts of samples No. 1 to No. 6, respectively, and it can be seen from the results that the catalysts have the characteristics of high hydrogen efficiency, high space-time yield and good stability.

FIG. 7 is a TEM photograph of sample # 1 catalyst; the noble metal of the catalyst is highly dispersed on the silicon oxide carrier in a nanometer shape.

FIG. 8 is a statistical plot of the pore size distribution of the support of sample # 1, with pore sizes centered at 10-15nm, favoring the intramolecular diffusion of anthraquinone.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims

1. A platinum-palladium-silver trimetal composite catalyst is characterized by comprising a carrier and an active component loaded on the carrier;

the support comprises silica;

the active component comprises an active element;

the active elements include platinum, palladium and silver.

2. The catalyst according to claim 1, wherein the mass percentage of the platinum in the catalyst is 0.1-0.5 wt%;

the mass percentage of the palladium in the catalyst is 0.02-0.3 wt%;

the mass percentage of the silver in the catalyst is 0.05-0.5 wt%;

preferably, the mass percentage of the silver in the catalyst is 0.1-0.4 wt%;

wherein the mass of palladium is measured as the mass of palladium element, the mass of platinum is measured as the mass of platinum element, and the mass of silver is measured as the mass of silver element.

3. The catalyst according to claim 1, wherein the support is spherical silica containing mesopores;

the aperture of the carrier is 2-50 nm;

preferably, the pore diameter of the carrier is 15-40 nm;

of said carrierThe specific surface area is 50-450 m²/g；

Preferably, the specific surface area of the carrier is 100-350 m²/g；

The pore volume of the carrier is 0.3-1.8 cc/g;

preferably, the pore volume of the carrier is 0.5-1.2 cc/g;

the bulk density of the carrier is 0.2-1.2 g/ml;

preferably, the bulk density of the carrier is 0.5-0.9 g/ml.

4. The catalyst according to claim 1, wherein the active component is a platinum palladium silver complex structure;

the platinum-palladium-silver duplex structure platinum-silver element is of an alloy structure, palladium and platinum-silver are synthesized to form nano heterojunction particles which are dispersed on the carrier, and the particle size of the active component is 1-15 nm;

preferably, the particle size of the active component is 1.5-5 nm.

5. Process for the preparation of a catalyst according to any one of claims 1 to 4, characterized in that it comprises at least the steps of:

a2) Respectively obtaining a solution containing a platinum precursor and a solution containing a silver precursor, soaking a carrier in the solution containing the platinum precursor and the silver precursor for treatment, drying or roasting and washing, and then soaking the obtained solid in the solution containing the palladium precursor to obtain a catalyst precursor; or

6. The method of claim 5, wherein the palladium precursor comprises a palladium halide complex and a palladium ammonia complex;

preferably, the palladium chloride complex comprises an inorganic palladium ammine complex;

preferably, the platinum precursor includes a platinum halide complex and a platinum ammonia complex;

preferably, the silver precursor is a silver diammine nitrate complex.

7. The method of claim 6, wherein the palladium ammonia complex is obtained by mixing a solution containing a palladium source with aqueous ammonia;

preferably, the palladium source is a soluble palladium salt;

preferably, the source of platinum is a soluble platinum salt;

the silver-ammonia complex is obtained by mixing salts containing a silver source with ammonia water;

8. The method according to claim 5, wherein the vector in step a1) and step a2), step a3) and step a4) is prepared by the following method:

2) molding the mixed slurry obtained in the step 1) in a high-temperature oil column through a jet flow generator, and then aging and roasting to obtain micron spherical silicon dioxide, namely the carrier;

preferably, the raw material in step 1) further comprises an additive;

preferably, the additive is selected from at least one of wollastonite, kaolin, silicon carbide fiber, glass fiber and talcum powder;

preferably, in the step 1), the mass percentage of the silicon dioxide powder in the mixed slurry is 10-30%;

the mass percentage of the silica sol in the mixed slurry is 60-80%;

the addition amount of the dispersing agent is SiO in the mixed slurry₂0.1-5% of the mass;

the additive is added into SiO in the mixed slurry₂0.1-5% of the mass;

SiO in the mixed slurry₂The molar ratio of the organic amine to the organic amine is 1: 0.05-0.2；

The molar ratio of the acid to the organic amine is 1: 1-3;

preferably, in the step 1), the particle size of the silicon dioxide powder is 0.1-2 μm;

preferably, SiO in the silica sol₂20-40% of SiO in silica sol₂The particle size of the (B) is 2-50 nm;

preferably, the acid is selected from at least one of organic acid and inorganic acid;

preferably, the organic acid comprises at least one of salicylic acid, acetic acid, oxalic acid and citric acid;

preferably, the inorganic acid comprises at least one of hydrochloric acid, nitric acid and phosphoric acid;

preferably, the dispersant is selected from at least one of methanol, ethanol, isopropanol, amine acetate, ammonium citrate, polyethylene glycol and polymaleic acid;

preferably, the organic amine is at least one selected from the group consisting of ethylenediamine, ethanolamine, triethylenediamine, diethylenetriamine, and hexamethylenetetramine;

preferably, in step 2), the oil in the oil column is selected from vacuum pump oil, transformer oil, paraffin oil, solvent oil, vegetable oil, C-containing oil₁₀～C₁₃At least one of mineral oils mixed with linear paraffins;

preferably, the temperature of the oil column is 80-150 ℃;

preferably, the aperture of the nozzle of the jet flow generator is 0.1-1.0 mm; the jet flow speed is 1-20 m/s;

preferably, in the step 2), the aging time is 3-24 h;

the roasting temperature is 500-700 ℃, and the roasting time is 10-24 h.

9. The method as claimed in claim 5, wherein the baking atmosphere in step a1), step a2), step a3), step a4) is at least one selected from oxygen and inert gas;

the detergent is selected from an aqueous solution or an alcohol solution;

preferably, the detergent is at least one selected from ammonia water, sodium bicarbonate solution, ethanol and methanol;

in the step b), the reducing atmosphere is selected from hydrogen or a mixed gas of hydrogen and an inactive gas;

the inert gas is selected from at least one of inert gases;

the reduction treatment conditions are as follows: the reduction temperature is 50-800 ℃, and the reduction time is 0.5-10.0 h;

preferably, the reduction treatment conditions are: the reduction temperature is 50-400 ℃, and the reduction time is 0.5-6 h.

10. Use of the catalyst of any one of claims 1 to 4, the catalyst prepared by the method of any one of claims 5 to 9, in the preparation of hydrogen peroxide by hydrogenation of anthraquinone;

preferably, the anthraquinone is selected from at least one of 2-ethyl anthraquinone, 2-amyl anthraquinone, 2-tert-butyl anthraquinone;

preferably, the reaction conditions are: the reaction temperature is 30-60 ℃; the reaction pressure is 0.01-3.0 Mpa; 7-350mL/min of hydrogen and 20-200h of liquid space velocity^-1；

Preferably, the reaction conditions are: the reaction temperature is 30-50 ℃; the reaction pressure is 0.03-0.3 Mpa; 7-90mL/min of hydrogen and 40-100h of liquid space velocity^-1。