CN114618486B - Platinum-palladium-silver compound catalyst and preparation method and application thereof - Google Patents

Platinum-palladium-silver compound catalyst and preparation method and application thereof Download PDF

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CN114618486B
CN114618486B CN202011459307.XA CN202011459307A CN114618486B CN 114618486 B CN114618486 B CN 114618486B CN 202011459307 A CN202011459307 A CN 202011459307A CN 114618486 B CN114618486 B CN 114618486B
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palladium
platinum
silver
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precursor
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CN114618486A (en
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王树东
苏宏久
周俊宏
李大卫
杨晓野
严华
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Dalian Institute of Chemical Physics of CAS
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/50—Silver
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/613—10-100 m2/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/615—100-500 m2/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/63—Pore volume
    • B01J35/633—Pore volume less than 0.5 ml/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/63—Pore volume
    • B01J35/635—0.5-1.0 ml/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/63—Pore volume
    • B01J35/638—Pore volume more than 1.0 ml/g
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B15/00—Peroxides; Peroxyhydrates; Peroxyacids or salts thereof; Superoxides; Ozonides
    • C01B15/01—Hydrogen peroxide
    • C01B15/022—Preparation from organic compounds
    • C01B15/023—Preparation from organic compounds by the alkyl-anthraquinone process

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Abstract

The application discloses a catalyst which takes platinum-palladium-silver trimetallic composite structure particles as an active component 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 complex structure, 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 trimetallic compound catalyst has good activity and low load, greatly reduces the use ratio 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 noble metals are 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 and a preparation method and application thereof, and belongs to the field of chemical catalytic materials.
Background
Hydrogen peroxide is an important chemical product, and because the oxygen generated after decomposition has various effects of bleaching, oxidizing, disinfecting, sterilizing and the like, has the characteristics of no byproducts, no special treatment and the like, and is widely applied to industrial and agricultural production such as papermaking, spinning, chemical industry and the like. The hydrogen peroxide is mainly used in three application fields of papermaking, textile and chemical synthesis. In the paper industry, the bleaching technology is changed from chlorine bleaching to hydrogen peroxide bleaching, and particularly, along with the supply and shortage of newsprint products, forest paper integrated pulping and waste paper regeneration deinking projects are on the horse in dispute, and the consumption of hydrogen peroxide in the paper industry is increased rapidly; in the textile industry, products are exported to meet the requirements of international markets on textile qualityThe hydrogen peroxide is adopted for bleaching, 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 increased, and the consumption of hydrogen peroxide in the fields is increased by 30%; because hydrogen peroxide has almost pollution-free characteristics, the hydrogen peroxide is called as a cleanest chemical product, is a most representative reagent of green chemistry, and in recent years, the application market field of the hydrogen peroxide is continuously expanded, and new applications are continuously developed besides three main application fields. Anthraquinone method is the most mature and mainstream technology 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 procedure is the core of the whole process. Commercial hydrogenation catalyst employed 0.3% Pd/Al 2 O 3 The catalyst has the defects of poor hydrogenation selectivity, low hydrogenation efficiency and the like. The development of a low-cost and high-selectivity hydrogenation catalyst for synthesizing high-concentration hydrogen peroxide is one of key technologies and technological development trends for realizing low-cost and high-efficiency hydrogen peroxide production by an anthraquinone method at the present stage.
Disclosure of Invention
According to one aspect of the application, a 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 regulated, so that the selectivity of the catalyst can be improved, the production efficiency is improved, the activity of the catalyst is improved by the cooperation of palladium and platinum elements, and the use amount of platinum noble metals is reduced; heterojunction particles formed by platinum-silver alloy and palladium in the catalyst are in a highly dispersed nano state, and have stronger interaction with a carrier, so that better 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 support and an active component supported on the support;
the support comprises silica;
the active component comprises an active element;
the active elements comprise three elements of platinum, palladium and silver.
In the present application, on the one hand, the catalyst selectivity is changed by modifying the carrier used for the catalyst and by adjusting the pore structure, specific surface area, etc. of the carrier, so that the catalyst can be operated at a higher conversion rate. On the other hand, by adjusting the active components and the synergistic effect of the three elements, the use amount of the platinum group element can be reduced greatly, and the noble metal Pd which is more expensive is used, so that 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 0.02-0.3wt%;
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%;
wherein the mass of silver is measured by the mass of silver element, the mass of palladium is measured by the mass of palladium element, and the mass of platinum is measured by the mass of platinum element.
Optionally, the upper limit of the mass percent of palladium in the catalyst is selected from 0.15wt%, 0.20wt%, 0.25wt% or 0.3wt%; the lower limit is selected from 0.02wt%, 0.05wt%, 0.1wt%, 0.15wt%, or 0.2wt%.
Optionally, the upper limit of the mass percent of the platinum in the catalyst is selected from 0.2wt%, 0.25wt%, 0.3wt%, 0.4wt% or 0.5wt%; the lower limit is selected from 0.1wt%, 0.2wt%, 0.25wt%, 0.3wt%, or 0.4wt%.
Optionally, the upper limit of the mass percent of silver in the catalyst is selected from 0.2wt%, 0.25wt%, 0.3wt%, 0.4wt% or 0.5wt%; the lower limit is selected from 0.1wt%, 0.15wt%, or 0.2wt%.
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 m 2 /g。
Optionally, the specific surface area of the carrier is 200-450 m 2 /g。
Optionally, the specific surface area of the carrier is 100-350 m 2 /g。
Alternatively, the pore volume of the support is from 0.3 to 1.8cc/g.
Alternatively, the pore volume of the support is from 0.5 to 1.2cc/g.
Optionally, the pore volume of the carrier is 0.5-1.5 ml/g.
Alternatively, the bulk density of the support is from 0.2 to 1.2g/ml.
Alternatively, the bulk density of the support is from 0.5 to 0.9g/ml.
Alternatively, the bulk density of the support is from 0.3 to 1.0g/ml.
Alternatively, the bulk density of the support is from 0.6 to 1.0g/ml.
Optionally, the active component is a platinum-palladium-silver complex;
the platinum-palladium-silver composite structure platinum-silver element is of an alloy structure, nano heterojunction particles formed by synthesizing palladium and platinum-silver 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 a heterojunction particle formed by platinum silver alloy and palladium;
the platinum-silver alloy and palladium form heterojunction particles which are dispersed on the carrier in a nano-form, and the particle size of the active component is 0.5-10.0 nm.
Optionally, the particle size of heterojunction particles formed by the platinum-silver alloy and palladium is 1.5-3.5 nm.
Optionally, the particle size of heterojunction particles formed by the platinum-silver alloy and palladium is 1.0-5.0 nm.
Optionally, the particle size of heterojunction particles formed by the platinum-silver alloy and palladium is 0.50-3.21 nm.
According to one aspect of the present application, there is provided a preparation method of the above platinum-palladium-silver composite catalyst, which is characterized by comprising at least the steps of:
a1 A mixed precursor solution containing a platinum precursor, a palladium precursor and a silver precursor is obtained, and a silicon oxide carrier is immersed in the mixed precursor solution to obtain a catalyst precursor; or alternatively
a2 Respectively obtaining a solution containing a platinum precursor and a solution containing a silver precursor, immersing a carrier in the solution containing the platinum precursor and the silver precursor for treatment, drying or roasting and washing, and immersing the obtained solid in the solution containing the palladium precursor to obtain a catalyst precursor; or alternatively
a3 A solution containing a platinum precursor is obtained, the carrier is immersed in the solution containing the platinum precursor for treatment, and the obtained solid is immersed in the solution containing the palladium precursor and the solution containing the silver precursor after drying or roasting and washing to obtain a catalyst precursor; or alternatively
a4 A solution containing a silver precursor is obtained, the carrier is immersed in the solution containing the silver precursor for treatment, and after drying or roasting and washing, the obtained solid is immersed in the solution containing the palladium precursor and the solution containing the platinum precursor, so as to obtain a catalyst precursor;
b) And (3) carrying out reduction treatment on the catalyst precursor obtained in a 1), a 2), a 4) or a 4) to obtain the platinum-palladium-silver composite catalyst.
In particular, in the present application, the catalyst precursor is obtained by two methods, namely co-impregnation and stepwise impregnation. In the co-impregnation method, a mixed solution containing both the palladium precursor and the platinum precursor and the silver precursor is first prepared, and then the support is impregnated in the mixed solution. In the step impregnation method, the carrier is first treated by immersing in a solution containing a platinum or silver precursor to obtain a semi-dry solid, and then the semi-dry solid is immersed in a solution containing palladium or platinum or silver precursor.
The palladium precursor includes a palladium halide complex and a palladium ammonia complex;
preferably, the palladium-chlorine complex comprises an inorganic ammine palladium complex;
preferably, the palladium precursor complex is selected from at least one of palladium dichloride, palladium dinitrodiammine, palladium tetramine nitrate and palladium tetramine chloride;
the platinum precursor comprises a platinum halogen complex and a platinum ammonia complex;
preferably, the platinum-chloride complex comprises an inorganic ammonia platinum complex;
preferably, the platinum precursor complex is selected from at least one of diammineplatinum dichloride, dinitrodiammineplatinum, diammineplatinum tetrachloride and tetraamineplatinum dichloride;
The silver precursor is a diammine silver nitrate complex;
optionally, the mass percentage concentration of palladium, platinum and silver in the mixed solution is 0.1-0.8wt%;
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 silver content in the mixed solution is calculated as the silver element content.
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 a salt 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 silver sources with 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 ammonia water under heating to obtain a solution containing a platinum ammonia complex.
Specifically, a salt containing a silver source is mixed with ammonia water 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 aqueous ammonia used to mix the palladium ammine complex solution, the platinum ammine complex solution and the silver ammine complex solution has a pH of 10 to 13.
Optionally, the aqueous ammonia has a pH of 10, 11, 12, 13.
Optionally, the a 2) is: mixing the obtained solution containing platinum ammonia complex and silver ammonia complex with ammonia water, soaking the carrier in the mixture, mixing and stirring, filtering, washing, drying and roasting to obtain solid;
mixing the obtained solution containing palladium ammonia complex with ammonia water, adding the obtained solid into the mixture, mixing and stirring the mixture, filtering the mixture, and washing the mixture to obtain the catalyst precursor.
Optionally, the a 3) is: mixing the obtained solution containing platinum ammonia complex with ammonia water, soaking the carrier in the mixture, mixing and stirring, filtering, washing, drying and roasting to obtain solid;
mixing the obtained solution containing palladium ammonia complex and silver ammonia complex with ammonia water, adding the obtained solid into the mixture, mixing and stirring the mixture, filtering the mixture, and washing the mixture to obtain the catalyst precursor.
Optionally, the a 4) is: mixing the obtained solution containing silver ammonia complex with ammonia water, immersing the carrier therein, mixing and stirring, filtering, washing, drying and roasting to obtain solid;
mixing the obtained solution containing palladium ammonia complex and silver ammonia complex with ammonia water, adding the obtained solid into the mixture, mixing and stirring the mixture, filtering the mixture, and washing the mixture to obtain the catalyst precursor.
Optionally, the drying condition is 100-140 ℃ for not less than 3 hours.
Alternatively, the drying condition is 120 ℃ for 4 hours.
Optionally, the carrier in step a 1) and step a 2), step a 3) and step a 4) is prepared by the following method:
1) Mixing raw materials containing silicon dioxide powder, silica sol, acid, dispersing agent and organic amine to obtain mixed slurry;
2) And (2) forming the mixed slurry obtained in the step (1) in a high Wen Youzhu by a jet generator, and then aging and roasting to obtain the micron spherical silica, namely the carrier.
Optionally, the raw materials in step 1) further comprise additives.
Optionally, the additive is at least one selected from wollastonite, kaolin, silicon carbide fiber, glass fiber and talcum powder.
Optionally, in 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 dispersing agent is added in an amount of SiO in the mixed slurry 2 0.1 to 5 percent of the mass.
Optionally, the additive is added into the mixed slurry in an amount of SiO 2 0.1% by mass5％。
Optionally, siO in the mixed slurry 2 The molar ratio of the catalyst 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 step 1), the silica powder has a particle size of 0.1 to 2 μm;
optionally, siO in the silica sol 2 The mass fraction of the silica sol is 20-40%, siO in the silica sol 2 The particle size of (2) is 2-50 nm.
Optionally, the acid is selected from at least one of an organic acid and an inorganic acid.
Optionally, the organic acid comprises at least one of salicylic acid, acetic acid, oxalic acid, and citric acid.
Optionally, the inorganic acid includes at least one of hydrochloric acid, nitric acid, and phosphoric acid.
Optionally, the dispersing agent is at least one selected from methanol, ethanol, isopropanol, amine acetate, ammonium citrate, polyethylene glycol and polymaleic acid.
Optionally, the organic amine is at least one selected from 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, and oil containing C 10 ～C 13 At least one of mineral oils of straight chain alkanes is mixed.
Alternatively, the temperature of the oil column is 80-150 ℃.
Optionally, the nozzle aperture of the jet generator is 0.1-1.0 mm; the jet velocity is 1-20 m/s.
Optionally, in step 2), the aging time is 3 to 24 hours.
Optionally, the roasting temperature is 500-700 ℃ and the roasting time is 10-24 h.
Optionally, the roasting atmosphere in the steps a 1), a 2), a 3) and a 4) is at least one selected from oxygen and inert gases;
Preferably, the inert gas in the roasting atmosphere is nitrogen or argon, and the oxygen volume percentage content 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 inactive gas.
Optionally, the inert gas is selected from at least one of inert gases.
Optionally, the inert gas is at least one selected from nitrogen and argon.
Optionally, the reducing atmosphere is a mixed atmosphere of hydrogen and nitrogen, and the volume percentage of the hydrogen in the mixed gas 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.
Alternatively, 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 ℃, 100 ℃, 150 ℃, 200 ℃, 300 ℃, 350 ℃, 400 ℃, 500 ℃, 600 ℃ or 700 ℃.
Optionally, the upper limit of the reduction time is 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h; the lower limit is 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h or 9h.
According to a further aspect of the application, the application of the platinum-palladium-silver composite catalyst prepared by any one of the catalysts and the method in preparing hydrogen peroxide by anthraquinone hydrogenation is provided.
Optionally, the anthraquinone is at least one selected from 2-ethyl anthraquinone, 2-amyl anthraquinone and 2-tertiary butyl anthraquinone.
Alternatively, the reaction conditions are: the reaction temperature is 30-60 ℃; the reaction pressure is 0.01-3.0 Mpa; hydrogen 7-350mL/min and liquid space velocity 20-200h -1 。
Alternatively, the reaction conditions are: the reaction temperature is 30-50 ℃; the reaction pressure is 0.03-0.3 Mpa; hydrogen 7-90mL/min and liquid space velocity 40-100h -1 。
Alternatively, the reaction conditions are: the reaction temperature is 40 ℃; the reaction pressure is 0.1Mpa; hydrogen 70mL/min and liquid space velocity 50-80h -1 。
Optionally, the anthraquinone is selected from 2-ethyl anthraquinone, and anthraquinone hydrogenation reaction is carried out at 30-60 ℃.
In the hydrogenation process of producing hydrogen peroxide by anthraquinone method, the main reaction is hydrogenation reaction of carbonyl and carbon-carbon double bond on benzene ring, and according to the reaction characteristics, the hydrogenation reaction of carbon-carbon double bond on benzene ring should be limited to improve the selectivity of catalyst, thereby reducing the occurrence degree of deep hydrogenation side reaction. When palladium and platinum exist simultaneously, the adsorption capacity of hydrogen is larger than that of hydrogen when one element exists, and the adsorption capacity of carbonyl is weaker than that of platinum when one element exists, so that the mass fraction of noble metal elements of the catalyst is greatly reduced, electrons can be promoted to be transferred from palladium and platinum to silver by the existence of silver, the adsorption of palladium and platinum to hydrogen is enhanced, and the hydrogen activation capacity of the 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 silver and the carrier under the overflow action of hydrogen, 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 the high reaction selectivity is realized. The cost of the catalyst is obviously reduced, and the catalyst has good popularization and application values.
In the hydrogenation process for producing hydrogen peroxide by the anthraquinone method, because anthraquinone molecules are larger, diffusion is limited in the catalyst, and excessive hydrogenation of anthraquinone can be caused to generate irreversible side reaction after the anthraquinone stays on the catalyst for too long, so that the selectivity is reduced. The pore structure of the catalyst support thus has a great influence on the catalyst performance. Silicon oxide has adjustable specific surface and pore volume, so that it plays an important role in the fields of catalysis and separation. The preparation of the silica with specific pore diameter has very important significance for the selectivity, separation efficiency of separation and purification in the anthraquinone hydrogenation process. 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 interactions formed between the active ingredient and the silica support.
The composition of the active components, the particle size and the dispersity of the catalyst have important influences on the activity, the selectivity and the stability of the catalyst. One of the main methods of adjusting the composition and particle size of the active component to improve the catalyst activity and selectivity. The active components used in the mainstream anthraquinone hydrogenation catalyst are palladium or bimetallic active components taking palladium as a main component, but the requirements of high activity and high selectivity for high-concentration hydrogen peroxide production cannot be met at the same time only by adjusting the dispersity of palladium, and the requirement of the catalyst for reducing noble metal loading cannot be met only by the synergistic effect of palladium and a second metal element. The palladium platinum is taken 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 regulated, and the catalyst cost is remarkably reduced.
The application has the beneficial effects that:
(1) The platinum and palladium are adopted as main active components, and the hydrogen activating capacity is improved through the electronic effect and the geometric effect of the platinum and palladium, so that the catalyst noble metal loading capacity is reduced more favorably, and the quality of more expensive palladium element is reduced particularly;
(2) The addition of silver can better disperse and fix palladium and platinum elements, so that the utilization efficiency of platinum and palladium is improved, and the performance of the catalyst is improved;
(3) The active metal heterojunction in the catalyst presents 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 evaluating the hydrogenation performance of sample No. 1;
FIG. 2 is a graph showing the results of evaluation of hydrogenation performance of sample No. 2;
FIG. 3 is a graph showing the results of evaluating the hydrogenation performance of sample No. 3;
FIG. 4 is a graph showing the results of evaluating the hydrogenation performance of sample No. 4;
FIG. 5 is a graph showing the results of evaluation of hydrogenation performance of sample No. 5;
FIG. 6 is a graph showing the results of evaluating the hydrogenation performance of sample No. 6.
Fig. 7 is a TEM photograph of sample No. 1 catalyst.
FIG. 8 is a statistical chart of the pore size distribution of the carrier of sample No. 1.
Detailed Description
The present application is described in detail below with reference to examples, but the present application is not limited to these examples.
Unless otherwise indicated, all starting materials in the examples of the present application were purchased commercially.
In accordance with one embodiment of the present application,
1. a Pt-Pd-Ag catalyst for preparing hydrogen peroxide by anthraquinone hydrogenation uses mesoporous silicon dioxide as carrier and Pt as catalyst component x Pd y Ag 1-x-y /SiO 2 The catalyst is prepared by adopting an impregnation method, is prepared by washing, drying and reducing, is subjected to 2-ethylanthraquinone hydrogenation activity test at the reaction temperature of 30-60 ℃ and is loaded with 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 is 0.02-0.3 wt% and the content of silver is 0.05-0.5 wt%
2. The carrier is formed mesoporous silica, the shape of the carrier is spherical, and the pore diameter of the catalyst particles is 2-50 nm.
3. The specific surface area of the carrier is 100-350 m 2 Per gram, the pore volume is 0.5-1.5 ml/g, and the bulk density is 0.6-1.0 g/ml.
4. A hydrogen reduction process is employed.
5. Firstly preparing acidic platinum-palladium-silver solution or salt into ammonia complex precursor, impregnating the precursor solutions of three metals on a silicon oxide carrier together or step by step, and then washing, drying, reducing and the like to obtain the platinum-palladium-silver composite material.
6. The palladium source used for preparing the platinum-palladium-silver catalyst is ammonium tetrachloropalladate or palladium nitrate, palladium chloride or ammonium hexachloropalladate, the platinum source is tetrachloroplatinic acid, platinum nitrate, hexachloroplatinic acid or sodium hexachloroplatinate, and the silver source is silver nitrate or silver oxide or 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-form, and the nano-particle size of the metal particles is 1.0-5.0 nm.
Example 1
(1-1) weighing SiO with an average particle diameter of 2 μm 2 21g of powder, 15ml of concentrated hydrochloric acid and SiO 2 126g (wherein SiO) of 30% by weight of alkaline silica sol 2 The average particle size of (2) is 25 nm) and 10ml of methanol are fully mixed, 15g of hexamethylenetetramine is added, and fully dissolved, thus obtaining mixed slurry;
(1-2) selecting a nozzle with the aperture of 0.25mm, mounting the nozzle to a jet generator, injecting the mixed slurry obtained in the step (1-1) into 25# transformer oil with the temperature of 95 ℃ at the speed of 5m/s for molding, standing and aging for 4 hours, separating molded pellets from the oil, and vacuum drying for 12 hours at the temperature of 80 ℃. Washing the obtained product to be neutral, drying at 140 ℃ for 10 hours, and roasting at 550 ℃ for 12 hours to obtain micron spherical silicon oxide particles, namely a carrier;
(1-3) weighing 3.3600g of PdCl 2 (palladium content: 59.5%) was dissolved in 20ml of deionized water to prepare a solution, and the solution was heated to a slight boiling point, followed by adding PdCl thereto 2 Dropwise adding 1ml of 25% ammonia water into the solution until precipitation is generated and then completely dissolved to obtain a palladium tetra-ammine dichloride solution, and fixing the volume to 100.00ml to obtain a solution containing palladium ammine complex;
(1-4) weighing 5.00. 5.00g K 2 PtCl 4 (platinum content 47.0%), 2.5mL of concentrated hydrochloric acid in 75mL of water. The solution was taken in a 150mL beaker, 4g of ammonium chloride was dissolved, and about 10mL of 3mol/L NH was carefully added 3 ·H 2 O until neutral, adding 6.75ml3mol/L NH 3 ·H 2 O, placing the solution into a refrigerator, placing until the green-yellow solid precipitate is completely generated, changing the supernatant from dark red to light yellow (24-48 h), filtering the precipitate, and washing the precipitate with ice water for a plurality of times (10 mL each time). Transferring the precipitate to a 250mL Erlenmeyer flask, adding 1mol/L HCl to make the volume to 150mL, heating the mixture to boil, cooling and then fixing the volume to 200mL to obtain a solution containing platinum ammonia complex;
(1-5) weighing 2.00g AgNO 3 (silver content: 63.5%) was dissolved in 20ml deionized water to prepare a solution, which was heated to slight boiling, and then was subjected to AgNO 3 2ml of 25% ammonia water is dripped into the solution until precipitation is generated and dissolved again completely, and the volume is fixed to 100.00ml, thus obtaining the solution containing silver ammonia complex;
(1-6) transferring 512. Mu.L of a solution containing a platinum ammonia complex and 472. Mu.L of a solution containing a silver ammonia complex to 149.0mL of an aqueous ammonia solution having a pH of 12, adding 6g of the spherical silica particles prepared in the 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;
(1-7) placing the solid in (1-6) in a tube furnace, at O 2 And N 2 Mixed gas (O) 2 Roasting for 4 hours at 400 ℃ in the atmosphere with the volume percentage of 10% in the mixed gas, cooling, taking out, washing with deionized water, and drying for 2 hours at 120 ℃ to obtain a solid;
(1-8) transferring 300 mu L of the solution containing the palladium-ammonia complex to 149.7mL of ammonia water solution with pH=12, adding the calcined solid prepared in the step (1-7), mixing, fully 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, at H 2 And N 2 Mixed gas (H) 2 Reducing for 3 hours at 400 ℃ in the atmosphere with the volume percentage of 10% in the mixed gas 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 0.1wt%, the mass percent of platinum in the sample was 0.1wt%, and the mass percent of silver in the sample was 0.1wt%.
Example 2
(2-1) weighing SiO having an average particle diameter of 2 μm 2 21g of powder, 5ml of concentrated nitric acid and SiO 2 126g (wherein SiO) of 30% by weight of alkaline silica sol 2 25 nm) and ethanol 10ml, and then adding 2g (300 meshes) of wollastonite and 15g of hexamethylenetetramine, and fully dissolving to obtain mixed slurry;
(2-2) selecting a nozzle with a pore diameter of 0.25mm, mounting the nozzle to a jet generator, injecting the mixed slurry obtained in (2-1) into 25# transformer oil at 90 ℃ at a speed of 5m/s for molding, standing and aging for 4 hours, separating molded pellets from the oil, and vacuum drying at 60 ℃ for 24 hours. Washing the obtained product to be neutral, drying at 140 ℃ for 10 hours, and roasting at 550 ℃ for 12 hours to obtain micron spherical silicon oxide particles, namely a carrier;
(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 slight boiling, and then purified to Pd (NO) 3 ) 2 1ml of 28% ammonia water is dripped into the solution until precipitation is completely dissolved again, thus obtaining a light green transparent tetraammine palladium nitrate solution, and the volume is fixed to 50.00ml, thus obtaining a solution containing palladium ammonia complex;
(2-4) weighing 2gK 2 PtCl 6 Adding 100ml of water (with platinum content of 46.2%) into the mixture, adding 20g of sodium nitrite for reaction, stirring and heating the mixture, changing the solution into transparent and light green yellow, cooling after no gas is generated, adding 12ml of 20% ammonia water solution, boiling slowly, cooling and fixing the volume to 200ml to obtain the platinum ammonia complex Is a solution of (a);
(2-5) weighing 4.00g AgNO 3 (silver content: 63.5%) was dissolved in 20ml deionized water to prepare a solution, which was heated to slight boiling, and then was subjected to AgNO 3 Dropwise adding 5ml of 10% ammonia water into the solution until precipitation is completely dissolved again, and fixing the volume to 200.00ml to obtain a solution containing silver ammonia complex;
(2-6) transferring 2600. Mu.L of a solution containing a platinum ammonia complex and 236. Mu.L of a solution containing a silver ammonia complex to 147.1mL of an aqueous ammonia solution having a pH of 12, adding 6g of the spherical silica particles produced in the step (2-2), 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;
(2-7) placing the solid in (2-6) in a tube furnace, at O 2 And N 2 Mixed gas (O) 2 Roasting for 4 hours at 500 ℃ in the atmosphere of 50% by volume of mixed gas, cooling, taking out, washing with ethanol, and drying for 2 hours at 120 ℃ to obtain a solid;
(2-8) transferring 300 μl of the solution containing palladium-ammonia complex to 149.7mL of ammonia water solution with ph=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 roasting at 400 ℃ for 2 hours to obtain a catalyst precursor;
(2-9) placing the catalyst precursor in a tube furnace, at H 2 And N 2 Mixed gas (H) 2 Reducing for 6 hours at 300 ℃ in an atmosphere with the volume percentage of 5% in the mixed gas to obtain a platinum-palladium-silver compound catalyst, which is marked as sample No. 2;
in sample 2# the mass percent of palladium in the sample was 0.1wt%, the mass percent of platinum in the sample was 0.2wt%, and the mass percent of silver in the sample was 0.05wt%.
Example 3
(3-1) weighing SiO with an average particle diameter of 2 μm 2 31g of powder, 10ml of concentrated phosphoric acid and SiO 2 126g (wherein SiO) of 30% by weight of alkaline silica sol 2 25nm average particle size) and 8ml of polyethylene glycol are thoroughly mixedAdding 2.5g (500 meshes) of silicon carbide fibers and 14g of hexamethylenetetramine, and fully dissolving to obtain mixed slurry;
(3-2) selecting a nozzle with a pore diameter of 0.35mm, mounting the nozzle to a jet generator, injecting the mixed slurry obtained in the step (3-1) into 25# transformer oil with a temperature of 90 ℃ at a speed of 5m/s for molding, standing and aging for 5 hours, separating molded pellets from the oil, and vacuum drying for 16 hours at 80 ℃. Washing the obtained product to neutrality, drying at 140 deg.C for 10 hr, and roasting at 550 deg.C for 12 hr to obtain micron spherical silica particles, i.e. carrier.
(3-3) weighing 1.6800g of PdCl 2 (palladium content: 59.5%) was dissolved in 10ml of deionized water to prepare a solution, and the solution was heated to a slight boiling point, and then added to PdCl 2 1ml of 26% ammonia water is dripped into the solution until precipitation is completely dissolved again, thus obtaining a light green transparent tetra-ammine palladium dichloride solution, and the volume is fixed to 50.00ml, thus obtaining a solution containing palladium ammine complex;
(3-4) weighing 50ml of the solution in (1-4), heating to 75 ℃ on a water bath, keeping the temperature, stirring by a stirrer, slowly introducing chlorine, supplementing 50ml of water during the stirring, stopping introducing the chlorine after keeping for 3 hours, boiling excessive chlorine to remove, and cooling to reach a volume of 200ml to obtain the solution containing the platinum ammonia complex;
(3-5) 3.38g of AgCl (silver content: 75.2%) was weighed into 20ml of deionized water, and 1. 1gNH was added at the same time 4 NO 3 Heating to slight boiling, dripping 5ml of 10% ammonia water into the solution to precipitate and dissolve completely, and fixing volume to 200.00ml to obtain silver ammonia complex-containing solution;
(3-6) transferring 750. Mu.L of the solution containing palladium ammine complex, 512. Mu.L of the solution containing silver ammine complex and 1310. Mu.L of the solution containing platinum ammine complex to 147.5mL of an aqueous ammonia solution having pH=10 to obtain a mixed solution containing platinum palladium silver;
(3-7) weighing 6.0g of the spherical silicon oxide particles prepared in the step (3-2), adding the spherical silicon oxide particles into the mixed solution containing platinum-palladium-silver in the step (3-6), mixing, fully stirring at 30 ℃ for 2.0 hours, filtering, washing with deionized water, and drying at 120 ℃ for 2 hours to obtain a catalyst precursor;
(3-8) placing the catalyst precursor in a tube furnace, at H 2 And N 2 Mixed gas (H) 2 Reducing for 2 hours at 350 ℃ in the atmosphere with the volume percentage of 10% in the mixed gas, cooling, washing with 1% ammonia water, and drying for 2 hours at 120 ℃ to obtain a platinum-palladium-silver composite catalyst, which is marked as sample No. 3;
in sample 3# the mass percent of palladium in the sample was 0.25wt%, the mass percent of platinum in the sample was 0.1wt%, and the mass percent of silver in the sample was 0.1wt%.
Example 4
(4-1) SiO having an average particle diameter of 2. Mu.m 2 21g of powder, 5ml of concentrated hydrochloric acid and SiO 2 126g (wherein SiO) of 30% by weight of alkaline silica sol 2 The average particle size of (2 nm) and 10ml of isopropyl alcohol were thoroughly mixed, and 15g of hexamethylenetetramine was further added thereto for sufficient dissolution to obtain a mixed slurry.
(4-2) selecting a nozzle with a pore diameter of 0.2mm, mounting the nozzle to a jet generator, injecting the mixed slurry obtained in the step (4-1) into 25# transformer oil at 85 ℃ at a speed of 1m/s for molding, standing and aging for 7 hours, separating molded pellets from the oil, and vacuum drying at 60 ℃ for 12 hours. Washing the obtained product to neutrality, drying at 140 deg.C for 10 hr, and roasting at 550 deg.C for 12 hr to obtain micron spherical silica particles, i.e. 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 slight boiling, and then purified to Pd (NO) 3 ) 2 Dropwise adding 1ml of 10% ammonia water into the solution until precipitation is completely dissolved again to obtain a tetraammine palladium nitrate solution, and fixing the volume to 50.00ml to obtain a solution containing palladium ammine complex;
(4-4) 1.00g PtCl was weighed out 2 (platinum content 73.6%) was dissolved in 10ml deionized water to prepare a solution, which was heated to slightly boiling, and then subjected to PtCl 2 1ml of 25% ammonia water is dripped into the solution until precipitation is generated and then is completely dissolved, thus obtaining light green transparent dichloro tetra ammine platinum solution, and the volume is fixed to 50.00ml, thus obtaining the platinum-ammonia-containing solutionA solution of the complex;
(4-5) 3.38g AgCl (75.2% silver) was weighed into 20ml deionized water, with 2gNH added 4 NO 3 Heating to slight boiling, dripping 5ml of 25% ammonia water into the solution to precipitate and dissolve completely, and fixing volume to 200.00ml to obtain silver ammonia complex-containing solution;
(4-6) transferring 408. Mu.L of the solution containing the platinum ammonia complex to 149.6mL of an aqueous ammonia solution having a pH of 12, adding 6g of the spherical silica particles prepared in the step (1-2), 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;
(4-7) placing the solid in (4-6) in a tube furnace, at O 2 And N 2 Mixed gas (O) 2 Roasting for 4 hours at 250 ℃ in the atmosphere with the volume percentage of 80% in the mixed gas, cooling, taking out, washing with 1% sodium bicarbonate solution, and drying for 2 hours at 120 ℃ to obtain a solid;
(4-8) transferring 600. Mu.L of the solution containing the palladium ammonia complex and 236. Mu.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 roasting at 400℃for 2 hours to obtain a catalyst precursor;
(4-9) placing the catalyst precursor in a tube furnace, at H 2 And N 2 Mixed gas (H) 2 Reducing for 6 hours at 200 ℃ in the atmosphere with the volume percentage of 10% in the mixed gas to obtain a platinum-palladium-silver compound catalyst, which is marked as sample No. 4;
in sample 4# the mass percent of palladium in the sample was 0.2wt%, the mass percent of platinum in the sample was 0.1wt%, and the mass percent of silver in the sample was 0.05wt%.
Example 5
(5-1) SiO having an average particle diameter of 2. Mu.m 2 47.1g of powder, 15ml of concentrated hydrochloric acid and SiO 2 126g (wherein SiO) of 30% by weight of alkaline silica sol 2 Average particle size of 12 nm) and B5ml of alcohol was thoroughly mixed, and 14g of hexamethylenetetramine was added thereto to be sufficiently dissolved, thereby obtaining a mixed slurry.
(5-2) selecting a nozzle with a pore diameter of 1mm, mounting the nozzle to a jet generator, injecting the mixed slurry obtained in (5-1) into 25# transformer oil with a temperature of 95 ℃ at a speed of 2m/s for molding, standing and aging for 10 hours, separating molded pellets from the oil, and vacuum drying for 12 hours at 80 ℃. Washing the obtained product to neutrality, drying at 110 ℃ for 20 hours, and roasting at 550 ℃ for 12 hours to obtain micron spherical silicon oxide particles, namely the carrier.
(5-3) weighing 1.6800g PdCl 2 (palladium content: 59.5%) was dissolved in 10ml of deionized water to prepare a solution, and the solution was heated to a slight boiling point, and then added to PdCl 2 Dropwise adding 1ml of 27% ammonia water into the solution until precipitation is completely dissolved again to obtain a light green transparent tetra-ammine palladium dichloride solution, and fixing the volume to 50.00ml to obtain a solution containing palladium ammine complex;
(5-4) weighing 5.00. 5.00g K 2 PtCl 4 (platinum content 47.0%), 5mL of concentrated hydrochloric acid in 50mL of water. The solution was taken in a 150mL beaker, 5g of ammonium chloride was dissolved, and about 10mL of 3mol/L NH was carefully added 3 ·H 2 O until neutral, adding 6.75ml3mol/L NH 3 ·H 2 O, placing the solution into a refrigerator, placing until the green-yellow solid precipitate is completely generated, changing the supernatant from dark red to light yellow (24-48 h), filtering the precipitate, and washing the precipitate with ice water for several times (20 mL each time). Transferring the precipitate to a 250mL Erlenmeyer flask, adding 1mol/L HCl to make the volume to 150mL, heating the mixture to boil, cooling and then fixing the volume to 200mL to obtain a solution containing platinum ammonia complex;
(5-5) weighing 2.73g of Ag 2 O (silver content 93.1%) was added to 20ml deionized water with 2gNH 4 NO 3 Heating to slight boiling, dripping 5ml of 25% ammonia water into the solution to precipitate and dissolve completely, and fixing volume to 200.00ml to obtain silver ammonia complex-containing solution;
(5-6) transferring 1530. Mu.L of the solution containing the platinum ammonia complex to 148.5mL of an aqueous ammonia solution having a pH of 12, adding 6g of the spherical silica particles prepared in the step (5-2), mixing, sufficiently stirring at 60℃for 3.0 hours, filtering the mixed solution, 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, at O 2 And N 2 Mixed gas (O) 2 Roasting for 4 hours at 250 ℃ in the atmosphere with the volume percentage of 80% in the mixed gas, cooling, taking out, washing with 1% sodium bicarbonate solution, and drying for 2 hours at 120 ℃ to obtain a solid;
(5-8) transferring 1200 μl of the solution containing palladium ammonia complex and 236 μl of the solution containing silver ammonia complex to 148.5mL of ammonia water solution with ph=12, adding the dried solid prepared in step (5-7), mixing, stirring thoroughly at 50deg.C for 2.0 hours, filtering, washing with 1% sodium bicarbonate solution, oven drying at 120deg.C for 2 hours to obtain catalyst precursor;
(5-9) placing the catalyst precursor in a tube furnace, at H 2 And N 2 Mixed gas (H) 2 Reducing for 2 hours at 400 ℃ in the atmosphere with the volume percentage of 20% in the mixed gas to obtain a platinum-palladium-silver catalyst, which is marked as sample No. 5;
in sample 5# the mass percent of palladium in the sample was 0.1wt%, the mass percent of platinum in the sample was 0.3wt%, and the mass percent of silver in the sample was 0.05wt%.
Example 6
(6-1) SiO having an average particle diameter of 2. Mu.m 2 18.1g of powder, 15ml of concentrated hydrochloric acid and SiO 2 126g (wherein SiO) of 30% by weight of alkaline silica sol 2 The average particle size of (2 nm) and 10ml of ethanol, and then 14g of hexamethylenetetramine was added thereto for sufficient dissolution to obtain a mixed slurry.
(6-2) selecting a nozzle with a pore diameter of 0.3mm, mounting the nozzle to a jet generator, injecting the mixed slurry obtained in (6-1) into 25# transformer oil with a temperature of 95 ℃ at a speed of 20m/s for molding, standing and aging for 12 hours, separating molded pellets from the oil, and vacuum drying at 80 ℃ for 12 hours. Washing the obtained product to neutrality, drying at 110 ℃ for 20 hours, and roasting at 550 ℃ for 12 hours 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 slight boiling, and then purified to Pd (NO) 3 ) 2 1ml of 25% ammonia water is dripped into the solution until precipitation is completely dissolved again, thus obtaining a light green transparent tetraammine palladium nitrate solution, and the volume is fixed to 50.00ml, thus obtaining a solution containing palladium ammonia complex;
(6-4) 1.00g PtCl was weighed 2 (platinum content 73.6%) was dissolved in 30ml deionized water to prepare a solution, which was heated to slightly boiling, and then subjected to PtCl 2 Dropwise adding 10ml of 5% ammonia water into the solution until precipitation is completely dissolved again to obtain a dichloro tetra-ammine platinum solution, and fixing the volume to 100ml to obtain a platinum ammine complex-containing solution;
(6-5) weighing 2.73g of Ag 2 O (93.1% silver) was added to 30ml deionized water with 0.5. 0.5gNH 4 NO 3 Heating to slight boiling, dropwise adding 20ml of 5% ammonia water into the solution until precipitation is completely dissolved again, and fixing the volume to 200.00ml to obtain a solution containing 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 the step (5-2), mixing, sufficiently stirring at 60℃for 3.0 hours, filtering the mixed solution, 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, at O 2 And N 2 Mixed gas (O) 2 Roasting for 4 hours at 250 ℃ in an atmosphere with the volume percentage of 80% in the mixed gas to obtain a solid;
(6-8) transferring 300. Mu.L of the solution containing the palladium ammonia complex and 1630. Mu.L of the solution containing the platinum ammonia complex to 148.0mL of ammonia water solution with pH=13, adding the dried solid prepared in the step (6-7), mixing, sufficiently stirring at 50 ℃ for 2.0 hours, filtering, washing with 1% sodium bicarbonate solution, and drying in an oven at 120 ℃ for 2 hours to obtain a catalyst precursor;
(6-9) placing the catalyst precursor in a tube furnace, at H 2 And N 2 Mixed gas (H) 2 In a mixed gasThe volume percentage of the catalyst is 20 percent) is reduced for 3 hours at 350 ℃ in the atmosphere, and the platinum-palladium-silver compound catalyst is obtained and is marked as sample No. 6;
in sample 6# the mass percent of palladium in the sample was 0.1wt%, the mass percent of platinum in the sample was 0.2wt%, and the mass percent of silver in the sample was 0.4wt%.
Example 7
The catalyst evaluation is carried out in a high-pressure reaction kettle, and specifically comprises the following steps of firstly preparing working solution (the mass content of 2-amylanthraquinone in the working solution is 170 g/L) from heavy aromatic hydrocarbon, diisobutylcarbinol (volume ratio is 3:2) and 2-amylanthraquinone, respectively adding 0.7g of sample No. 1-6 catalyst and 120mL of 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 15mL/min. The water bath temperature is controlled to 45 ℃ and the pressure is controlled to about 0.1 MPa.
Oxidizing the hydrogenated solution with oxygen, extracting with distilled water, and then using KMnO 4 The generated hydrogen peroxide was measured by titration, and the hydrogenation efficiency (hydrogen efficiency) was calculated. The hydrogenated liquid is the working liquid taken out from the reaction kettle after the hydrogenation reaction is completed.
Wherein:
b-hydrogenation efficiency (g/L);
C—KMnO 4 concentration (mol/L) of the solution;
V 0 —KMnO 4 volume of solution (mL);
M—H 2 O 2 molar mass (g/mol);
v-volume of hydrogenated liquid (mol/L).
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 by the following formula:
wherein:
STY-production of Hydrogen peroxide per gram of platinum and Palladium per day mass (kg) H2O2 g -1 PtPd d -1 )；
B-catalyst hydrogenation efficiency (kg.L) calculated according to the foregoing formula -1 )；
Q L Flow rate of anthraquinone working solution (L.d -1 )；
m-loading mass of catalyst (g);
θ Pd catalyst platinum to palladium content (wt%).
FIGS. 1-6 are the results of evaluating the hydrogenation performance of the catalysts of samples 1-6, respectively, and it can be seen from the figures 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 No. 1 catalyst; the noble metal of the catalyst is highly dispersed on the silicon oxide carrier in a nano-form.
FIG. 8 is a statistical plot of the pore size distribution of sample 1# for carriers with pore diameters centered at 10-15nm, which facilitates intramolecular diffusion of anthraquinone.
While the application has been described in terms of preferred embodiments, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of the application, and it is intended that the application is not limited to the specific embodiments disclosed.

Claims (13)

1. A platinum-palladium-silver trimetallic composite catalyst, characterized by comprising a support and an active component supported on the support;
the support comprises silica;
the active component comprises an active element;
the active elements include platinum, palladium and silver;
the mass percentage of the platinum in the catalyst is 0.1-0.5wt%;
the mass percentage of the palladium in the catalyst is 0.02-0.3wt%;
the mass percentage of the silver in the catalyst is 0.05-0.5wt%;
wherein the mass of palladium is measured by the mass of palladium element, the mass of platinum is measured by the mass of platinum element, and the mass of silver is measured by the mass of silver element;
the carrier is spherical silicon dioxide containing mesopores;
The aperture of the carrier is 2-50 nm;
the specific surface area of the carrier is 50-450 m 2 /g；
The pore volume of the carrier is 0.3-1.8 cc/g;
the bulk density of the carrier is 0.2-1.2 g/mL;
the active component is of a platinum-palladium-silver composite structure;
the platinum-palladium-silver composite structure platinum-silver element is of an alloy structure, nano heterojunction particles formed by palladium and platinum-silver alloy are dispersed on the carrier, and the particle size of the active component is 1-15 nm.
2. The catalyst according to claim 1, wherein the mass percentage of the platinum in the catalyst is 0.15-0.3 wt%;
the mass percentage of the palladium in the catalyst is 0.05-0.2wt%;
the mass percentage of the silver in the catalyst is 0.1-0.4wt%;
wherein the mass of palladium is measured by the mass of palladium element, the mass of platinum is measured by the mass of platinum element, and the mass of silver is measured by the mass of silver element.
3. The catalyst of claim 1, wherein the catalyst is,
the aperture of the carrier is 15-40 nm;
the specific surface area of the carrier is 100-350 m 2 /g；
The pore volume of the carrier is 0.5-1.2 cc/g;
the bulk density of the carrier is 0.5-0.9 g/mL.
4. The catalyst of claim 1, wherein the catalyst is,
The particle size of the active component is 1.5-5 nm.
5. The method for preparing a catalyst according to any one of claims 1 to 4, comprising at least the steps of:
a1 A mixed precursor solution containing a platinum precursor, a palladium precursor and a silver precursor is obtained, and a silicon oxide carrier is immersed in the mixed precursor solution to obtain a catalyst precursor;
or alternatively;
a2 Respectively obtaining a solution containing a platinum precursor and a solution containing a silver precursor, immersing a carrier in the solution containing the platinum precursor and the silver precursor for treatment, drying or roasting and washing, and immersing the obtained solid in the solution containing the palladium precursor to obtain a catalyst precursor;
or alternatively;
a3 A solution containing a platinum precursor is obtained, the carrier is immersed in the solution containing the platinum precursor for treatment, and the obtained solid is immersed in the solution containing the palladium precursor and the solution containing the silver precursor after drying or roasting and washing to obtain a catalyst precursor;
or alternatively;
a4 A solution containing a silver precursor is obtained, the carrier is immersed in the solution containing the silver precursor for treatment, and after drying or roasting and washing, the obtained solid is immersed in the solution containing a palladium precursor and a platinum precursor to obtain a catalyst precursor;
b) And (3) carrying out reduction treatment on the catalyst precursor obtained in a 1), a 2), a 3) or a 4) to obtain the platinum-palladium-silver composite catalyst.
6. The method of claim 5, wherein the palladium precursor is selected from at least one of palladium dichloride, palladium dinitrodiammine, palladium tetrammine nitrate, palladium tetrammine chloride;
the platinum precursor is at least one of diammineplatinum dichloride, dinitrodiammineplatinum, diammineplatinum tetrachloride and tetraammine platinum dichloride;
the silver precursor is a diammine silver nitrate complex.
7. The method of claim 6, wherein the palladium precursor is obtained by mixing a solution containing a palladium source with ammonia;
the palladium source is at least one selected from ammonium tetrachloropalladate, palladium nitrate, palladium chloride and ammonium hexachloropalladate;
the platinum precursor is obtained by mixing salts containing a platinum source with ammonia water;
the platinum source is at least one selected from potassium tetrachloroplatinate, potassium hexachloroplatinate and platinum dichloride;
the silver precursor is obtained by mixing salts containing silver sources with ammonia water;
the silver source is at least one selected from silver nitrate, silver oxide and silver chloride.
8. The method according to claim 5, wherein the carrier in step a 1) and step a 2), step a 3) and step a 4) is prepared by:
1) Mixing raw materials containing silicon dioxide powder, silica sol, acid, dispersing agent and organic amine to obtain mixed slurry;
2) Molding the mixed slurry obtained in the step 1) in a high Wen Youzhu through a jet generator, and then aging and roasting to obtain micron spherical silicon dioxide, namely the carrier;
the raw materials in the step 1) also comprise additives;
the additive is at least one of wollastonite, kaolin, silicon carbide fiber, glass fiber and talcum powder;
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 slurry 2 0.1-5% of the weight;
the addition amount of the additive is SiO in the mixed slurry 2 0.1-5% of the weight;
SiO in the mixed slurry 2 The 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;
In the step 1), the particle size of the silicon dioxide powder is 0.1-2 mu m;
SiO in the silica sol 2 The mass fraction of the silica sol is 20-40%, and SiO in the silica sol is 2 The grain size of the particles is 2-50 nm;
the acid is at least one of organic acid and inorganic acid;
the organic acid is at least one of salicylic acid, acetic acid, oxalic acid and citric acid;
the inorganic acid is at least one of hydrochloric acid, nitric acid and phosphoric acid;
the dispersing agent is at least one selected from methanol, ethanol, isopropanol, amine acetate, ammonium citrate, polyethylene glycol and polymaleic acid;
the organic amine is at least one selected from ethylenediamine, ethanolamine, triethylenediamine, diethylenetriamine and hexamethylenetetramine;
in the step 2), the oil in the oil column is selected from vacuum pump oil, transformer oil, paraffin oil, solvent oil, vegetable oil and C-containing oil 10 ~C 13 Mixing at least one of mineral oils of linear alkanes;
the temperature of the oil column is 80-150 ℃;
the aperture of a nozzle of the jet flow generator is 0.1-1.0 mm; the jet flow speed is 1-20 m/s;
in the step 2), the aging time is 3-24 hours;
the roasting temperature is 500-700 ℃, and the roasting time is 10-24 hours.
9. The method according to claim 5, wherein the firing atmosphere in step a 1), step a 2), step a 3), and step a 4) is at least one selected from the group consisting of oxygen and inert gas;
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 aqueous solution or alcohol solution;
in the step b), the reducing atmosphere is selected from hydrogen or a mixed gas of hydrogen and an inactive gas;
the inactive gas is at least one selected from 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.
10. The method according to claim 5, wherein the detergent is at least one selected from the group consisting of ammonia, sodium bicarbonate solution, ethanol, and methanol.
11. The method of claim 5, wherein the reducing treatment conditions: the reduction temperature is 50-400 ℃, and the reduction time is 0.5-6 h.
12. Use of the catalyst of any one of claims 1 to 4 or the catalyst prepared by the method of any one of claims 5 to 11 in the preparation of hydrogen peroxide by hydrogenation of anthraquinone;
the anthraquinone is at least one selected from 2-ethyl anthraquinone, 2-amyl anthraquinone and 2-tertiary butyl anthraquinone;
reaction conditions: the reaction temperature is 30-60 ℃; the reaction pressure is 0.01-3.0 MPa; hydrogen 7-350 mL/min and liquid space velocity 20-200 h -1 。
13. The use according to claim 12, wherein the reaction conditions are: the reaction temperature is 30-50 ℃; the reaction pressure is 0.03-0.3 MPa; hydrogen 7-90 mL/min, liquid space velocity 40-100 h -1 。
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