Ruthenium-silver / carbon catalyst and preparation method and application thereof

Abstract

The invention discloses a ruthenium-silver / carbon catalyst and a preparation method and application, belonging to the technical field of catalyst preparation. The ruthenium-silver / carbon catalyst provided by the present invention is composed of a carrier and ruthenium-silver alloy nanoparticles loaded on the carrier, wherein the carrier is activated carbon, the loading amount of ruthenium is 1wt%-5wt%, and the loading ratio of ruthenium to silver is 1:1-1:4. The catalyst provided above uses activated biochar as a carrier, loads ruthenium-silver alloy nanoparticles on the carrier, and disperses catalytic active species ruthenium with cheaper silver. The catalyst is used to catalyze the hydrogenation of phenol to prepare cyclohexanol, which has the advantages of high efficiency and good selectivity, mild reaction conditions, and reusable catalysts.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and in particular to a ruthenium-silver / carbon catalyst and a preparation method and application thereof. Background Art

[0002] Cyclohexanol is an indispensable chemical intermediate in modern industry. It is widely used in rubber preparation, emulsifier, plasticizer and resin and other chemical fields. It is mainly used to produce adipic acid, hexamethylenediamine, cyclohexanone and caprolactam. It can also be used as a stabilizer for soap, to make disinfectant soap and detergent emulsion, as a solvent for rubber, resin, nitrocellulose, metal soap, oil, ester and ether, as an admixture for coatings, and as a degreasing agent, stripping agent, dry cleaning agent and polish for leather. Cyclohexanol is also a raw material for fiber finishing agents, pesticides and plasticizers. The main methods for producing cyclohexanol are phenol hydrogenation and cyclohexane oxidation.

[0003] At present, nickel catalyst is generally used for phenol hydrogenation. The reaction temperature is 150℃ and the pressure is 2.5MPa. The yield is close to the theoretical value, the product purity is high, and the reaction is stable. In view of the price of raw materials, the cyclohexane oxidation method has gradually replaced the phenol hydrogenation method. The cyclohexane oxidation reaction is relatively complicated. It first generates cyclohexyl hydroperoxide and then decomposes into cyclohexanol and cyclohexanone. Cyclohexanol and cyclohexanone are easier to oxidize than cyclohexane; most of the cyclohexanone is generated by the oxidation of cyclohexanol, and cyclohexanone will generate various oxidation by-products.

[0004] In view of the above problems, it is necessary to provide a ruthenium-silver / carbon catalyst and a preparation method and application thereof. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a ruthenium-silver / carbon catalyst and a preparation method and application thereof.

[0006] The present invention solves the technical problem by adopting the following technical solutions.

[0007] The invention provides a ruthenium-silver / carbon catalyst, which consists of a carrier and ruthenium-silver alloy nanoparticles loaded on the carrier, wherein the carrier is activated carbon, the loading amount of ruthenium is 1wt%-5wt%, and the loading ratio of ruthenium to silver is 1:1-1:4.

[0008] The present invention also provides a method for preparing the above-mentioned ruthenium-silver / carbon catalyst, comprising: mixing activated carbon with a ruthenium salt solution and a silver salt solution, and then using a reducing agent to reduce the ruthenium metal ions and silver metal ions in the solution into ruthenium-silver alloy nanoparticles and load them on the activated carbon to obtain a ruthenium-silver / carbon catalyst.

[0009] The present invention also provides an application of the ruthenium-silver / carbon catalyst in preparing cyclohexanol by catalytic hydrogenation of phenol.

[0010] The present invention has the following beneficial effects:

[0011] The present invention provides a ruthenium-silver / carbon catalyst and a preparation method and application thereof. The ruthenium-silver / carbon catalyst is composed of a carrier and ruthenium-silver alloy nanoparticles loaded on the carrier. The above-provided catalyst uses activated carbon as a carrier. The activated carbon carrier can disperse and anchor the ruthenium-silver alloy nanoparticles. At the same time, relatively cheap silver is used to disperse the ruthenium species in the catalytic active center, so that the catalytic activity of the ruthenium species can be fully exerted. The obtained ruthenium-silver / carbon catalyst is used for phenol hydrogenation to produce cyclohexanol, which has the advantages of high efficiency and good selectivity, mild reaction conditions, and the catalyst can be reused, which is significantly better than the traditional cyclohexanol production method. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0013] Figure 1 This is the TEM-mapping image of 2wt% ruthenium-6wt% silver / food waste fermentation residue activated carbon. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0015] The following is a detailed description of a ruthenium-silver / carbon catalyst, a preparation method and an application thereof provided in an embodiment of the present invention.

[0016] In the first aspect, an embodiment of the present invention provides a ruthenium-silver / carbon catalyst, which is composed of a carrier and ruthenium-silver alloy nanoparticles loaded on the carrier, wherein the carrier is activated carbon, the ruthenium loading is 1wt%-5wt%, and the ruthenium and silver loading ratio is 1:1-1:4.

[0017] The embodiment of the present invention provides a ruthenium-silver / carbon catalyst, which is composed of a carrier and ruthenium-silver alloy nanoparticles loaded on the carrier. The catalyst provided above utilizes silver to disperse the ruthenium species in the catalytic active center, and can give full play to the catalytic activity of ruthenium. The activated carbon carrier can play the role of dispersing and anchoring the ruthenium-silver alloy nanoparticles. The catalyst obtained in this way is used for the hydrogenation of phenol to produce cyclohexanol, and exhibits good catalytic activity.

[0018] In an optional embodiment, the loading amount of ruthenium is 2 wt%-3 wt%, and the loading ratio of ruthenium to silver is 1:1.5-1:2.

[0019] In an optional embodiment, the activated carbon is obtained by the following method: roasting biomass to obtain biochar, and then activating and roasting the biochar to obtain activated carbon;

[0020] Preferably, the biomass comprises any one of fermentation residues, plant biomass and animal biomass;

[0021] More preferably, the fermentation residue is mainly prepared by anaerobic fermentation of kitchen waste and anaerobic sludge;

[0022] More preferably, the animal biomass is selected from hide meal;

[0023] More preferably, the plant biomass is selected from birch wood flour.

[0024] It is worth mentioning that for the preparation of activated carbon from fermentation residue, the inventor can refer to the patent already applied for by the inventor: ZL202111564362.X, which utilizes the carbon and nitrogen elements in the fermentation residue of food waste to prepare a nitrogen-containing porous activated carbon carrier with a high specific surface area, which is beneficial to the loading and attachment of metal particles.

[0025] In a second aspect, an embodiment of the present invention provides a method for preparing the above-mentioned ruthenium-silver / carbon catalyst, comprising: mixing activated carbon with a ruthenium salt solution and a silver salt solution, and then using a reducing agent to reduce the ruthenium metal ions and silver metal ions in the solution into ruthenium-silver alloy nanoparticles and load them on the activated carbon to obtain a ruthenium-silver / carbon catalyst.

[0026] In an optional embodiment, the following steps are included:

[0027] The biomass is roasted and activated to obtain activated carbon, and then the obtained activated carbon is mixed evenly with ruthenium salt, silver salt and deionized water in proportion, and ultrasonicated at room temperature to make the activated carbon uniformly adsorb metal ions. After the ultrasonication, the activated carbon is centrifuged and washed to remove the supernatant;

[0028] Under ultrasonic conditions, a reducing agent is added to carry out a reduction reaction. After the reaction is completed, the catalyst is centrifuged, washed and dried to obtain a ruthenium-silver / carbon catalyst.

[0029] In an optional embodiment, the ruthenium salt includes at least one of ruthenium chloride, ruthenium nitrate, potassium chlororuthenate, and chlororuthenic acid, and the silver salt is silver nitrate.

[0030] In an optional embodiment, the reducing agent includes at least one selected from NaBH4, formaldehyde, glycine, and ethylene glycol solution;

[0031] Preferably, the reducing agent is selected from sodium borohydride, and the molar ratio of sodium borohydride to the total amount of metals in the ruthenium salt and the silver salt is 3:1.

[0032] In an optional embodiment, the drying temperature is 60-110° C. and the drying time is 6-24 h.

[0033] In a third aspect, an embodiment of the present invention provides an application of the above-mentioned ruthenium-silver / carbon catalyst in the catalytic hydrogenation of phenol to prepare cyclohexanol.

[0034] In an optional embodiment, the catalytic hydrogenation comprises: reacting phenol in a water system under the action of a hydrogen atmosphere and a ruthenium-silver / carbon catalyst to obtain cyclohexanol.

[0035] In an optional embodiment, in the catalytic hydrogenation, the mass molar ratio of the ruthenium-silver / carbon catalyst to phenol is 25-150 mg:1 mmol; and the dosage ratio of phenol to water is 2.5 mmol:25 mL.

[0036] Preferably, the hydrogen pressure is 0.5-4 MPa, more preferably 1-2 MPa;

[0037] Preferably, the reaction temperature is 30-90°C, more preferably 50-70°C; the reaction time is 0.5-4h, more preferably 1-2h.

[0038] As can be seen from the above, the embodiment of the present invention provides a ruthenium-silver / carbon catalyst, which is composed of a carrier and ruthenium-silver alloy nanoparticles loaded on the carrier, wherein the carbon-based catalyst carrier is prepared from food waste, leather waste or agricultural and forestry waste as raw materials, which can not only realize the resource utilization of solid waste, but also, if food waste is used as raw material, due to the rich carbon and nitrogen elements in the food waste, a nitrogen-containing porous activated carbon carrier with a high specific surface area can be prepared without adding an external nitrogen source, which can play a role in dispersing and anchoring ruthenium-silver metal nanoparticles. In addition, the catalytic activity of ruthenium can be fully exerted by dispersing active metal ruthenium with cheaper silver. The inventor has also proved through many experiments that when the catalyst is used for preparing cyclohexanol by hydrogenation of phenol, the conditions are milder, the reaction time is shorter, the efficiency and selectivity of cyclohexanol are good, and the catalyst can be reused, which is significantly better than the traditional cyclohexanol production method.

[0039] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0040] The method provided by the present invention mainly prepares a carbon-based catalyst carrier from solid waste, loads ruthenium-silver alloy nanoparticles on the carrier, and uses silver to disperse the active center ruthenium to obtain a catalyst composed of ruthenium-silver / carbon. The catalyst can efficiently reduce phenol to cyclohexanol under mild conditions.

[0041] Example 1

[0042] Preparation of activated carbon: The kitchen waste and anaerobic sludge were crushed and adjusted to TSS of 20g / L, mixed in a ratio of 9:1, and adjusted to pH 8 with sodium bicarbonate. The fermentation was carried out at room temperature for 8 days, and the kitchen waste fermentation residue was obtained by washing and centrifugation for many times. The fermentation residue was roasted in a tubular furnace at 450℃ nitrogen atmosphere for 2h, and the obtained biochar was soaked in a 4mol / L KOH solution at a mass ratio of 4:1 for 12h, and then the mixture was dried. The dried biochar was roasted in a tubular furnace at 800℃ nitrogen atmosphere for 2h, washed to neutrality and dried to obtain activated carbon.

[0043] ② Catalyst preparation: (0.595mL of 0.1mol / L chlororuthenic acid solution, 1.670mL of 0.1mol / L AgNO3 solution, 0.3g of activated carbon, 3mL of water) were added to a 50mL centrifuge tube, and ultrasonicated at room temperature for 2h in an ultrasonicator to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, the mixture was centrifuged and washed three times with distilled water in a high-speed centrifuge, and the supernatant was removed. After the centrifugal washing, NaBH4 solution was added to the centrifuge tube to make the molar ratio of NaBH4 to metal 3:1, and ultrasonicated again for 1h. After the ultrasonication, the mixture was centrifuged and washed three times. After the ultrasonication, the solid was dried in an oven at 105℃ to obtain a ruthenium-silver / carbon catalyst with a loading of 2.0wt% ruthenium and 6.0wt% silver.

[0044] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of ruthenium-silver / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 2.0MPa, and the reaction was carried out at a temperature of 90°C for 30min. The phenol conversion rate was measured by gas chromatography to be 99.9%, and the cyclohexanol yield was 99.7%.

[0045] The TEM-mapping image of the ruthenium-silver / carbon catalyst prepared in Example 1 above is shown in Figure 1 ,Depend on Figure 1 It can be seen that ruthenium and silver are evenly dispersed on the activated carbon carrier, and the signals of ruthenium and silver are highly overlapped to form ruthenium-silver alloy nanoparticles. The catalytic activity of ruthenium species can be fully exerted by using relatively cheap silver to disperse the ruthenium species in the catalytic active center.

[0046] Example 2

[0047] ① The preparation of activated carbon is the same as described in Example 1.

[0048] ② Catalyst preparation: (0.300mL of 0.1mol / L chlororuthenic acid solution, 0.840mL of 0.1mol / L AgNO3 solution, 0.3g of activated carbon, 3mL of water) were added to a 50mL centrifuge tube, and ultrasonicated at room temperature for 2h in an ultrasonicator to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, the mixture was centrifuged and washed three times with distilled water in a high-speed centrifuge, and the supernatant was removed. After the centrifugal washing, NaBH4 solution was added to the centrifuge tube to make the molar ratio of NaBH4 to metal 3:1, and ultrasonicated again for 1h. After the ultrasonication, the mixture was centrifuged and washed three times. After the ultrasonication, the solid was dried in an oven at 105℃ to obtain a ruthenium-silver / carbon catalyst with a loading of 1.0wt% ruthenium and 3.0wt% silver.

[0049] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 150mg of ruthenium-silver / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 3.0MPa, and the reaction was carried out at a temperature of 70°C for 120min. The phenol conversion rate was 99.5% and the cyclohexanol yield was 99.2% as measured by gas chromatography.

[0050] Example 3

[0051] ① The preparation of activated carbon is the same as described in Example 1.

[0052] ② Catalyst preparation: Take (0.595mL of 0.1mol / L chlororuthenic acid solution, 1.115mL of 0.1mol / L AgNO3 solution, 0.3g of activated carbon, 3mL of water) and add them to a 50mL centrifuge tube. Ultrasonicate at room temperature for 2h in an ultrasonic instrument to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, centrifuge and wash three times with distilled water in a high-speed centrifuge, and remove the supernatant. After the centrifugal washing, add NaBH4 solution to the centrifuge tube so that the molar ratio of NaBH4 to metal is 3:1, and ultrasonicate again for 1h. After the ultrasonication, centrifuge and wash three times. After the end, dry the solid in a 105℃ oven to obtain a ruthenium-silver / carbon catalyst with a loading of 2.0wt% ruthenium and 4.0wt% silver.

[0053] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of ruthenium-silver / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 2.0MPa, and the reaction was carried out at a temperature of 70°C for 90min. The phenol conversion rate was 99.7% and the cyclohexanol yield was 99.5% as measured by gas chromatography.

[0054] Example 4

[0055] ① The preparation of activated carbon is the same as described in Example 1.

[0056] ② Catalyst preparation: (1.485mL of 0.1mol / L chlororuthenic acid solution, 1.390mL of 0.1mol / L AgNO3 solution, 0.3g of activated carbon, 3mL of water) were added to a 50mL centrifuge tube, and ultrasonicated at room temperature for 2h in an ultrasonicator to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, the mixture was centrifuged and washed three times with distilled water in a high-speed centrifuge, and the supernatant was removed. After the centrifugal washing, NaBH4 solution was added to the centrifuge tube to make the molar ratio of NaBH4 to metal 3:1, and ultrasonicated again for 1h. After the ultrasonication, the mixture was centrifuged and washed three times. After the ultrasonication, the solid was dried in an oven at 105℃ to obtain a ruthenium-silver / carbon catalyst with a loading of 5.0wt% ruthenium and 5.0wt% silver.

[0057] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 25mg of ruthenium-silver / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 1.5MPa, and the reaction was carried out at a temperature of 70°C for 60min. The phenol conversion rate was 84.9% and the cyclohexanol yield was 84.5% as measured by gas chromatography.

[0058] Example 5

[0059] ① The preparation of activated carbon is the same as described in Example 1.

[0060] ② Catalyst preparation: (0.595mL of 0.1mol / L chlororuthenic acid solution, 2.225mL of 0.1mol / L AgNO3 solution, 0.3g of activated carbon, 3mL of water) were added to a 50mL centrifuge tube, and ultrasonicated at room temperature for 2h in an ultrasonicator to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, the mixture was centrifuged and washed three times with distilled water in a high-speed centrifuge, and the supernatant was removed. After the centrifugal washing, NaBH4 solution was added to the centrifuge tube to make the molar ratio of NaBH4 to metal 3:1, and ultrasonicated again for 1h. After the ultrasonication, the mixture was centrifuged and washed three times. After the ultrasonication, the solid was dried in an oven at 105℃ to obtain a ruthenium-silver / carbon catalyst with a loading of 2.0wt% ruthenium and 8.0wt% silver.

[0061] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 75mg of ruthenium-silver / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 4.0MPa, and the reaction was carried out at a temperature of 50°C for 120min. The phenol conversion rate was 99.9% and the cyclohexanol yield was 99.7% as measured by gas chromatography.

[0062] Example 6

[0063] ① The preparation of activated carbon is the same as described in Example 1.

[0064] ② Catalyst preparation: Take (0.895mL of 0.1mol / L chlororuthenic acid solution, 1.255mL of 0.1mol / L AgNO3 solution, 0.3g of activated carbon, 3mL of water) and add them to a 50mL centrifuge tube. Ultrasonicate at room temperature for 2h in an ultrasonic instrument to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, centrifuge and wash three times with distilled water in a high-speed centrifuge, and remove the supernatant. After the centrifugal washing, add NaBH4 solution to the centrifuge tube so that the molar ratio of NaBH4 to metal is 3:1, and ultrasonicate again for 1h. After the ultrasonication, centrifuge and wash three times. After the end, dry the solid in a 105℃ oven to obtain a ruthenium-silver / carbon catalyst with a loading of 3.0wt% ruthenium and 4.5wt% silver.

[0065] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 150mg of ruthenium-silver / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 4.0MPa, and the reaction was carried out at a temperature of 30°C for 240min. The phenol conversion rate was 86.5% and the cyclohexanol yield was 86.1% as measured by gas chromatography.

[0066] Example 7

[0067] ① The preparation of activated carbon is the same as described in Example 1.

[0068] ② Catalyst preparation: Take (0.595mL of 0.1mol / L chlororuthenic acid solution, 1.115mL of 0.1mol / L AgNO3 solution, 0.3g of activated carbon, 3mL of water) and add them to a 50mL centrifuge tube. Ultrasonicate at room temperature for 2h in an ultrasonic instrument to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, centrifuge and wash three times with distilled water in a high-speed centrifuge, and remove the supernatant. After the centrifugal washing, add NaBH4 solution to the centrifuge tube so that the molar ratio of NaBH4 to metal is 3:1, and ultrasonicate again for 1h. After the ultrasonication, centrifuge and wash three times. After the end, dry the solid in a 105℃ oven to obtain a ruthenium-silver / carbon catalyst with a loading of 2.0wt% ruthenium and 4.0wt% silver.

[0069] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of ruthenium-silver / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 0.5MPa, and the reaction was carried out at a temperature of 70°C for 240min. The phenol conversion rate was 96.5% and the cyclohexanol yield was 96.1% as measured by gas chromatography.

[0070] Example 8

[0071] ① Preparation of activated carbon: Birch powder was calcined in a tubular furnace at 450°C in a nitrogen atmosphere for 2 h, the obtained biochar was soaked in a 4 mol / L KOH solution at a mass ratio of 4:1 for 12 h, and the mixture was dried. The dried biochar was calcined in a tubular furnace at 800°C in a nitrogen atmosphere for 2 h, washed to neutrality and then dried to obtain activated carbon.

[0072] ② Catalyst preparation: Take (0.595mL of 0.1mol / L chlororuthenic acid solution, 1.115mL of 0.1mol / L AgNO3 solution, 0.3g birch activated carbon, 3mL water) and add them to a 50mL centrifuge tube, ultrasonicate for 2h at about 20℃ in an ultrasonic cleaner to evenly mix the activated carbon and metal ions. After the ultrasonication, wash three times with secondary water in a high-speed refrigerated centrifuge to ensure that the supernatant is colorless. After the centrifugal washing, add 1.5mL of 5mg / mL NaBH4 solution to the centrifuge tube, and ultrasonicate for 1h again. After the ultrasonication, wash three times again by centrifugation. After the ultrasonication, dry the water in a 105℃ oven to obtain a ruthenium-silver / carbon catalyst with a loading of 2.0wt% ruthenium and 4.0wt% silver.

[0073] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of ruthenium-silver / carbon catalyst, 25mL of water, 2.0MPa of hydrogen pressure, 70℃ of temperature, and 60min of reaction time. Gas chromatography measured the phenol conversion rate to be 99.9% and the cyclohexanol yield to be 99.7%.

[0074] Example 9

[0075] ① Preparation of activated carbon: Tannery waste hide powder was calcined in a tubular furnace at 450°C in a nitrogen atmosphere for 2 h, the obtained biochar was soaked in a 4 mol / L KOH solution at a mass ratio of 4:1 for 12 h, and the mixture was dried. The dried biochar was calcined in a tubular furnace at 800°C in a nitrogen atmosphere for 2 h, washed to neutrality and then dried to obtain activated carbon.

[0076] ② Catalyst preparation: (0.595mL of 0.1mol / L chlororuthenic acid solution, 1.115mL of 0.1mol / L AgNO3 solution, 0.3g of leather powder activated carbon, 3mL of water) are added to a 50mL centrifuge tube, and ultrasonicated at about 20°C for 2h in an ultrasonic cleaning machine to uniformly mix the activated carbon and the metal ions. After the ultrasonication, the mixture is centrifuged and washed three times with secondary water in a high-speed refrigerated centrifuge to ensure that the supernatant is colorless. After the centrifugal washing, 1.5mL of 5mg / mL NaBH4 solution is added to the centrifuge tube, and ultrasonicated again for 1h. After the ultrasonication, the mixture is centrifuged and washed three times again. After the ultrasonication, the mixture is dried in a 105°C oven to obtain a ruthenium-silver / carbon catalyst with a loading of 2.0wt% ruthenium and 4.0wt% silver.

[0077] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of ruthenium-silver / carbon catalyst, 25mL of water, 2.0MPa of hydrogen pressure, 70℃ of temperature, and 60min of reaction time. Gas chromatography measured the phenol conversion rate to be 97.4% and the cyclohexanol yield to be 97.1%.

[0078] Table 1

[0079]

[0080] It can be seen from Table 1 above that when a carbon-based catalyst carrier is prepared using food waste (such as fermentation residues), leather waste (hide powder) or agricultural and forestry waste (such as birch powder) as raw materials, and ruthenium-silver alloy nanoparticles are loaded thereon, and used for catalytic hydrogenation of phenol, the phenol conversion rate and the cyclohexanol yield are very high, which are significantly better than the phenol conversion rate and cyclohexanol yield using conventional metals as catalysts.

[0081] Comparative Example 1

[0082] The steps are similar to those in Example 1, except that the metal nanoparticles supported by the activated carbon do not contain silver, but only contain single ruthenium nanoparticles. The experimental process and results are as follows:

[0083] ① The preparation of activated carbon is the same as described in Example 1.

[0084] ② Catalyst preparation: Take (0.595mL of 0.1mol / L chlororuthenic acid solution, 0.3g of activated carbon, 3mL of water) and add it to a 50mL centrifuge tube. Ultrasonicate it in an ultrasonic instrument at room temperature for 2h to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, centrifuge and wash it three times with distilled water in a high-speed centrifuge, and remove the supernatant. After the centrifugal washing, add NaBH4 solution to the centrifuge tube so that the molar ratio of NaBH4 to metal is 3:1, and ultrasonicate it again for 1h. After the ultrasonication, centrifuge and wash it three times. After the end, dry the solid in a 105℃ oven to obtain a ruthenium / carbon catalyst with a loading of 2.0wt% ruthenium.

[0085] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of ruthenium / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 2.0MPa, and the reaction was carried out at a temperature of 70°C for 60min. The phenol conversion rate was 41.5% and the cyclohexanol yield was 41.1% as measured by gas chromatography.

[0086] Comparative Example 2

[0087] The steps are similar to those of Comparative Example 1, except that the metal nanoparticles supported on the activated carbon are separate palladium nanoparticles. The experimental process and results are as follows:

[0088] ① The preparation of activated carbon is the same as described in Example 1.

[0089] ② Catalyst preparation: Take (0.565mL of 0.1mol / L K2PdCl4 solution, 0.3g of activated carbon, 3mL of water) and add it to a 50mL centrifuge tube. Ultrasonicate it in an ultrasonic instrument at room temperature for 2h to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, centrifuge and wash it three times with distilled water in a high-speed centrifuge, and remove the supernatant. After the centrifugal washing, add NaBH4 solution to the centrifuge tube so that the molar ratio of NaBH4 to metal is 3:1, and ultrasonicate it again for 1h. After the ultrasonication, centrifuge and wash it three times. After the end, dry the solid in a 105℃ oven to obtain a palladium / carbon catalyst with a loading of 2.0wt% palladium.

[0090] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of palladium / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 2.0MPa, and the reaction was carried out at 70°C for 60min. The phenol conversion rate was 2.3% and the cyclohexanol yield was 1.9% as measured by gas chromatography.

[0091] Comparative Example 3

[0092] The steps are similar to those of Comparative Example 1, except that the metal nanoparticles supported by the activated carbon are separate platinum nanoparticles. The experimental process and results are as follows:

[0093] ① The preparation of activated carbon is the same as described in Example 1.

[0094] ② Catalyst preparation: Take (0.310mL of 0.1mol / L H2PtCl6 solution, 0.3g of activated carbon, 3mL of water) and add it to a 50mL centrifuge tube. Ultrasonicate it in an ultrasonic instrument at room temperature for 2h to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, centrifuge and wash it three times with distilled water in a high-speed centrifuge, and remove the supernatant. After the centrifugal washing, add NaBH4 solution to the centrifuge tube so that the molar ratio of NaBH4 to metal is 3:1, and ultrasonicate it again for 1h. After the ultrasonication, centrifuge and wash it three times. After the end, dry the solid in a 105℃ oven to obtain a platinum / carbon catalyst with a platinum loading of 2.0wt%.

[0095] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of platinum / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 2.0MPa, and the reaction was carried out at a temperature of 70°C for 60min. The phenol conversion rate was 2.9% and the cyclohexanol yield was 2.5% as measured by gas chromatography.

[0096] Comparative Example 4

[0097] The steps are similar to those in Example 1, except that the reaction conditions in the catalytic process are changed to: ruthenium loading is 2.0 wt%, ruthenium silver loading ratio is 1 / 1, temperature is 70° C., hydrogen pressure is 2 MPa, and time is 1 h. The experimental process and results are as follows:

[0098] ① The preparation of activated carbon is the same as described in Example 1.

[0099] ② Catalyst preparation: (0.595mL of 0.1mol / L chlororuthenic acid solution, 0.560mL of 0.1mol / L AgNO3 solution, 0.3g of activated carbon, 3mL of water) were added to a 50mL centrifuge tube, and ultrasonicated at room temperature for 2h in an ultrasonicator to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, the mixture was centrifuged and washed three times with distilled water in a high-speed centrifuge, and the supernatant was removed. After the centrifugal washing, NaBH4 solution was added to the centrifuge tube to make the molar ratio of NaBH4 to metal 3:1, and ultrasonicated again for 1h. After the ultrasonication, the mixture was centrifuged and washed three times. After the ultrasonication, the solid was dried in an oven at 105℃ to obtain a ruthenium-silver / carbon catalyst with a loading of 2.0wt% ruthenium and 2.0wt% silver.

[0100] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of ruthenium-silver / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 2.0MPa, and the reaction was carried out at a temperature of 70°C for 60min. The phenol conversion rate was 60.7% and the cyclohexanol yield was 60.4% as measured by gas chromatography.

[0101] Comparative Example 5

[0102] The steps are similar to those of Comparative Example 4, except that the loaded bimetallic material is changed from ruthenium-silver bimetallic material to ruthenium-cobalt bimetallic material. The experimental process and results are as follows:

[0103] ① The preparation of activated carbon is the same as described in Example 1.

[0104] ② Catalyst preparation: Take (0.595mL of 0.1mol / L chlororuthenic acid solution, 1.020mL of 0.1mol / L Co(NO3)2 solution, 0.3g of activated carbon, 3mL of water) and add them to a 50mL centrifuge tube. Ultrasonicate for 2h at room temperature in an ultrasonic instrument to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, centrifuge and wash three times with distilled water in a high-speed centrifuge, and remove the supernatant. After the centrifugal washing, add NaBH4 solution to the centrifuge tube so that the molar ratio of NaBH4 to metal is 3:1, and ultrasonicate again for 1h. After the ultrasonication, centrifuge and wash three times. After the end, dry the solid in a 105℃ oven to obtain a ruthenium-cobalt / carbon catalyst with a loading of 2.0wt% ruthenium and 2.0wt% cobalt.

[0105] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of ruthenium-cobalt / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 2.0MPa, and the reaction was carried out at a temperature of 70°C for 60min. The phenol conversion rate was 45.5% and the cyclohexanol yield was 45.2% as measured by gas chromatography.

[0106] Comparative Example 6

[0107] The steps are similar to those of Comparative Example 4, except that the loaded bimetallic material is changed from ruthenium-silver bimetallic material to ruthenium-nickel bimetallic material. The experimental process and results are as follows:

[0108] ① The preparation of activated carbon is the same as described in Example 1.

[0109] ② Catalyst preparation: Take (0.595mL of 0.1mol / L chlororuthenic acid solution, 1.025mL of 0.1mol / L NiCl2 solution, 0.3g of activated carbon, 3mL of water) and add them to a 50mL centrifuge tube. Ultrasonicate for 2h at room temperature in an ultrasonic instrument to allow the activated carbon to fully adsorb metal ions. After the ultrasonication, centrifuge and wash three times with distilled water in a high-speed centrifuge, and remove the supernatant. After the centrifugal washing, add NaBH4 solution to the centrifuge tube so that the molar ratio of NaBH4 to metal is 3:1, and ultrasonicate again for 1h. After the ultrasonication, centrifuge and wash three times. After the end, dry the solid in a 105℃ oven to obtain a ruthenium-nickel / carbon catalyst with a loading of 2.0wt% ruthenium and 2.0wt% nickel.

[0110] ③ Catalytic hydrogenation of phenol: 2.5mmol of phenol, 100mg of ruthenium-nickel / carbon catalyst, and 25mL of water were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen, and the initial hydrogen pressure was maintained at 2.0MPa, and the reaction was carried out at a temperature of 70°C for 60min. The phenol conversion rate was 47.3% and the cyclohexanol yield was 46.9% as measured by gas chromatography.

[0111] Table 2

[0112]

[0113]

[0114] From Table 2 above, it can be seen that when the ruthenium-silver / carbon-carbon catalyst prepared in the comparative example is applied to the hydrogenation of phenol to cyclohexanol, although the effect of ruthenium is better than that of palladium and platinum, the effect of the single metal catalyst is much lower than that of the bimetallic ruthenium-silver catalyst. At the same time, the bimetallic catalyst with silver dispersed ruthenium has a better effect. Ruthenium-silver / carbon-carbon once again illustrates that the ruthenium-silver / carbon catalyst prepared by the embodiment of the present invention uses cheaper silver to disperse active metal ruthenium, and the catalyst has the advantages of good efficiency and selectivity, mild reaction conditions, and reusable catalyst for catalyzing the hydrogenation of phenol to cyclohexanol.

[0115] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A use of a ruthenium-silver / carbon catalyst in the catalytic hydrogenation of phenol to prepare cyclohexanol, characterized in that: The ruthenium-silver / carbon catalyst consists of a carrier and ruthenium-silver alloy nanoparticles loaded on the carrier, wherein the carrier is activated carbon, the loading amount of ruthenium is 1wt%-5wt%, and the loading ratio of ruthenium to silver is (1:1.5)-(1:2).

2. The use according to claim 1, characterized in that: The loading amount of ruthenium is 2wt%-3wt%.

3. The use according to claim 1, characterized in that: The activated carbon is obtained by the following method: biomass is roasted to obtain biochar, and then the biochar is activated and roasted to obtain the activated carbon.

4. The use according to claim 3, characterized in that: The biomass includes any one of fermentation residues, plant biomass and animal biomass.

5. The use according to claim 4, characterized in that: The fermentation residue is mainly prepared by anaerobic fermentation of kitchen waste and anaerobic sludge.

6. The use according to claim 4, characterized in that: The animal biomass is selected from hide meal.

7. The use according to claim 4, characterized in that: The plant biomass is selected from birch wood flour.

8. The use according to claim 1, characterized in that: The ruthenium-silver / carbon catalyst is prepared by the following method: activated carbon is mixed with a ruthenium salt solution and a silver salt solution, and then a reducing agent is used to reduce the ruthenium ions and silver ions in the solution into ruthenium-silver alloy nanoparticles and load them on the activated carbon to obtain the ruthenium-silver / carbon catalyst.

9. The use according to claim 8, characterized in that: The following steps are involved: The biomass is roasted and activated to obtain activated carbon, and then the obtained activated carbon is uniformly mixed with ruthenium salt, silver salt and deionized water in proportion, and ultrasonicated at room temperature to make the activated carbon uniformly adsorb metal ions. After the ultrasonication is completed, the activated carbon is centrifuged and washed to remove the supernatant; Under ultrasonic conditions, a reducing agent is added to carry out a reduction reaction. After the reaction is completed, the catalyst is centrifuged, washed and dried to obtain the ruthenium-silver / carbon catalyst.

10. The use according to claim 9, characterized in that: The ruthenium salt includes at least one of ruthenium chloride, ruthenium nitrate, chlororuthenic acid, and potassium chlororuthenate, and the silver salt is silver nitrate.

11. The use according to claim 9, characterized in that: The reducing agent includes at least one selected from NaBH4, formaldehyde, glycine, and ethylene glycol solution.

12. The use according to claim 9, characterized in that: The reducing agent is selected from sodium borohydride, and the molar ratio of the sodium borohydride to the total amount of metals in the ruthenium salt and the silver salt is 3:

1.

13. The use according to claim 1, characterized in that: The catalytic hydrogenation comprises: reacting phenol in a water system under the action of a hydrogen atmosphere and the ruthenium-silver / carbon catalyst to obtain cyclohexanol.

14. The use according to claim 13, characterized in that In the catalytic hydrogenation, the mass molar ratio of the ruthenium-silver / carbon catalyst to the phenol is 25-150 mg:1 mmol; the dosage ratio of the phenol to the water is 2.5 mmol:25 mL.

15. The use according to claim 14, characterized in that: The hydrogen pressure is 0.5-4 MPa.

16. The use according to claim 15, characterized in that The hydrogen pressure is 1-2 MPa.

17. The use according to claim 14, characterized in that: The reaction temperature is 30-90°C and the reaction time is 0.5-4h.

18. The use according to claim 17, characterized in that The reaction temperature is 50-70°C; the reaction time is 1-2h.

Images