A supported ruthenium-based catalyst, a method for preparing the same, and use thereof in the synthesis of ammonia reaction

Abstract

This application discloses a supported ruthenium-based catalyst, its preparation method, and its application in ammonia synthesis. The supported ruthenium-based catalyst comprises a metal oxide support, an active component, and a rare earth oxide promoter. The metal oxide support is selected from one or more of alumina, magnesium oxide, silicon oxide, titanium oxide, and zirconium oxide. The active component includes an active element, ruthenium. The promoter is a rare earth oxide, which is atomically dispersed. The rare earth oxide-modified supported ruthenium catalyst prepared by this invention exhibits excellent ammonia synthesis catalytic activity and stability under relatively mild conditions (300–400°C). Furthermore, the rare earth oxide promoter in this application is atomically dispersed on the catalyst surface, which can suppress the poisoning effect of hydrogen on the supported ruthenium catalyst and significantly improve the catalyst's ammonia synthesis activity.

Description

Technical Field

[0001] This application relates to a supported ruthenium-based catalyst, its preparation method, and its application in the ammonia synthesis reaction, belonging to the field of ammonia synthesis catalyst preparation technology. Background Technology

[0002] Ammonia is mainly used in the production of fertilizers, nitric acid, ammonium salts, and soda ash, and is one of the world's largest-produced chemical products. Social development and population growth have greatly boosted the production and consumption of ammonia-related industrial chemicals. Currently, the demand for ammonia-related industrial chemicals in fertilizers, plastics, pharmaceuticals, explosives, metallurgy, and environmental protection sectors is increasing daily. my country is the world's largest producer of synthetic ammonia, and the synthetic ammonia industry plays a vital role in the national economy. Compared with advanced international levels, my country's synthetic ammonia industry generally suffers from high energy consumption, high costs, and large CO2 emissions. In recent years, increasingly stringent policies on sustainable development and energy conservation and emission reduction have placed higher demands on my country's synthetic ammonia industry.

[0003] Ammonia synthesis has undergone a century of development, and its production processes have matured. Technological innovation in ammonia synthesis catalysts is key to reducing energy consumption and costs in the ammonia synthesis industry. Currently, fused iron catalysts are widely used in ammonia synthesis processes based on the Harber-Bosch process, requiring high-temperature (400–500℃) and high-pressure (10–30 MPa) reaction conditions. In 1992, BP and Kellogg successfully developed the KAAP process based on graphitized carbon-supported ruthenium catalysts (Ru / C), which offers advantages such as high reactivity, relatively mild reaction conditions, and low energy consumption. However, the methanation reaction of carbon supports under ammonia synthesis conditions leads to catalyst deactivation, limiting the widespread application of Ru / C catalysts. Developing novel ruthenium-based catalysts with high activity and stability under mild conditions is crucial for the development of the ammonia synthesis industry.

[0004] Compared to carbon supports, oxide supports have advantages such as large specific surface area, chemical stability, good mechanical strength, and ease of molding, and are widely used as supports for supported catalysts. Adding promoters to supported ruthenium-based ammonia synthesis catalyst systems can often significantly improve catalyst activity. The modification effect of promoters varies greatly depending on the support used in the ruthenium-based ammonia synthesis catalyst system. Currently, commonly used promoters for ruthenium-based ammonia synthesis catalysts mainly include alkali metal (alkaline earth metal) oxides or hydroxides. In addition, rare earth elements are also widely used as promoters for ruthenium-based ammonia synthesis catalysts. Studies have found that rare earth element-promoted Ru / γ-Al₂O₃ catalysts can alleviate the inhibitory effect of hydrogen in the ammonia synthesis reaction, resulting in higher catalytic activity under high pressure. The preparation of rare earth element-promoted supported ruthenium catalysts generally involves multiple steps: first, a supported ruthenium catalyst precursor is synthesized via impregnation; this precursor is then reduced at a specific temperature in a reducing atmosphere to obtain the supported ruthenium catalyst; next, a rare earth salt precursor is introduced into the reduction catalyst via impregnation; finally, it is activated at a specific temperature to obtain a rare earth oxide-promoted supported ruthenium ammonia synthesis catalyst. This catalyst preparation process is not only cumbersome and time-consuming, but also costly, limiting the practical application of rare earth oxide-promoted supported ruthenium ammonia synthesis catalysts.

[0005] Studies have found that the location and effect of the type of promoter in ruthenium-based catalysts are closely related to the catalyst preparation process and have a significant impact on the catalyst's catalytic performance. Therefore, to address the problems existing in the preparation of rare earth oxide-promoted supported ruthenium ammonia synthesis catalysts, it is particularly important to develop a catalyst preparation method that is simple in process, has a short preparation cycle, is low-cost, and easily scalable. Summary of the Invention

[0006] To overcome the shortcomings of existing preparation techniques, this application provides a simple and convenient one-step co-precipitation method to simultaneously precipitate rare earth metal salts and the active component ruthenium precursor onto the surface of a metal oxide support, thereby obtaining a high-performance rare earth oxide-modified supported ruthenium catalyst. This invention not only meets the demand for a low-cost, large-scale preparation method for modified supported ruthenium catalysts, but also produces rare earth oxide-modified supported ruthenium catalysts with excellent ammonia synthesis catalytic activity and stability under relatively mild conditions (300–400°C). Furthermore, the rare earth oxide promoters in this application are atomically dispersed on the catalyst surface, which can suppress the poisoning effect of hydrogen on the supported ruthenium catalyst and significantly improve the catalyst's ammonia synthesis activity.

[0007] According to one aspect of this application, a supported ruthenium-based catalyst is provided, the supported ruthenium-based catalyst comprising a metal oxide support, an active component, and a rare earth oxide promoter.

[0008] The metal oxide support is selected from one or more of aluminum oxide, magnesium oxide, silicon oxide, titanium oxide, and zirconium oxide.

[0009] The active component includes an active element, which is ruthenium.

[0010] The additive is a rare earth oxide;

[0011] The rare earth elements in the rare earth oxides are in an atomically dispersed state.

[0012] Optionally, the active component ruthenium is in an atomically dispersed state.

[0013] Optionally, the rare earth oxide is selected from one or more of cerium oxide, scandium oxide, yttrium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, and lutetium oxide;

[0014] Optionally, in the supported ruthenium-based catalyst,

[0015] The mass of the active component is 0.1% to 10% of the mass of the metal oxide support, wherein the mass of the active component is calculated based on the mass of the active element;

[0016] The molar ratio of the auxiliary agent to the active component is 0.1:1 to 10:1, wherein the number of moles of the auxiliary agent is calculated in terms of the number of moles of rare earth elements, and the number of moles of the active component is calculated in terms of the number of moles of active elements.

[0017] Optionally, the upper limit of the mass of the active component relative to the mass of the metal oxide support can be independently selected from 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.6%, or 0.3%; the lower limit can be independently selected from 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or 9%.

[0018] Optionally, the upper limit of the molar ratio of the adjuvant to the active component may be independently selected from 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1; and the lower limit may be independently selected from 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, and 9:1.

[0019] Among them, the content of additives has a significant impact on the catalyst, and the modification effect is optimal when the molar ratio of additives to ruthenium is 1:1.

[0020] Another aspect of this application provides a method for preparing the above-mentioned supported ruthenium-based catalyst, the method comprising:

[0021] The raw materials containing rare earth metal salts, ruthenium precursors, precipitants, and metal oxide supports are mixed with solvents and reacted to obtain a catalyst precursor. The catalyst precursor is then reduced to obtain the supported ruthenium-based catalyst.

[0022] Optionally, the rare earth element in the rare earth metal salt is selected from at least one of cerium, scandium, yttrium, lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium;

[0023] The rare earth metal salt is selected from one or more of rare earth chlorides, rare earth nitrates, rare earth acetates, and rare earth sulfates.

[0024] Optionally, the ruthenium precursor is selected from at least one ruthenium salt;

[0025] Optionally, the ruthenium salt is selected from one or more of ruthenium chloride, ruthenium nitrite, ruthenium acetylacetone, and potassium ruthenate;

[0026] Optionally, the precipitant is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, cesium hydroxide, sodium carbonate, potassium carbonate, and cesium carbonate;

[0027] Optionally, the metal oxide support is selected from one or more of alumina, magnesium oxide, silicon oxide, titanium oxide, and zirconium oxide;

[0028] Optionally, the solvent is water.

[0029] Optionally, the molar ratio of the precipitant to the ruthenium precursor is 1:1 to 400:1, wherein the amount of the precipitant is calculated based on the amount of the precipitant itself, and the amount of the ruthenium precursor is calculated based on the amount of ruthenium in the precursor.

[0030] Optionally, the molar ratio of the rare earth metal salt to the ruthenium precursor is 0.1:1 to 10:1, wherein the molar amount of the rare earth metal salt is calculated based on the amount of rare earth element, and the amount of the ruthenium precursor is calculated based on the amount of ruthenium element in the precursor.

[0031] Optionally, the upper limit of the molar ratio of the precipitant to the ruthenium precursor can be independently selected from 3:1, 10:1, 50:1, 100:1, 150:1, 200:1, 250:1, 300:1, 350:1, and 400:1; and the lower limit can be independently selected from 1:1, 3:1, 10:1, 50:1, 100:1, 150:1, 200:1, 250:1, 300:1, and 350:1.

[0032] Optionally, the upper limit of the molar ratio of the rare earth metal salt to the ruthenium precursor can be independently selected from 0.2:1, 0.5:1, 1:1, 2:1, 5:1, 8:1, and 10:1; the lower limit can be independently selected from 0.1:1, 0.2:1, 0.5:1, 1:1, 2:1, 5:1, and 8:1.

[0033] Optionally, the mass ratio of the metal oxide support to the ruthenium precursor is 10:1 to 100:1, wherein the mass of the metal oxide support is calculated based on the mass of the metal oxide, and the mass of the ruthenium precursor is calculated based on the mass of the ruthenium element.

[0034] Optionally, the upper limit of the mass ratio of the metal oxide support to the ruthenium precursor can be independently selected from 100:1, 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, and 20:1; and the lower limit can be independently selected from 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, 20:1, and 10:1.

[0035] Optionally, the method for preparing the catalyst precursor specifically includes:

[0036] The metal oxide support is mixed with a solution containing a precipitant, and then a mixed solution containing a ruthenium precursor and a rare earth metal salt is added. The reaction is carried out to obtain the catalyst precursor; wherein the reaction is a coprecipitation reaction.

[0037] Optionally, the reaction time is 0.1 to 48 hours;

[0038] Optionally, the upper limit of the reaction time can be independently selected from 48h, 44h, 39h, 35h, 30h, 24h, 19h, 12h, 7h, 2h, and 0.5h; the lower limit can be independently selected from 0.1h, 0.8h, 1.5h, 8h, 13h, 20h, 28h, 33h, 41h, and 47h.

[0039] Optionally, the reaction temperature is 10℃ to 50℃;

[0040] Optionally, the upper limit of the reaction temperature can be independently selected from 50°C, 40°C, 30°C, and 20°C; the lower limit can be independently selected from 10°C, 20°C, 30°C, and 40°C.

[0041] Optionally, the reduction conditions include: under a reducing atmosphere; a reduction temperature of 100–800°C; and a reduction time of 0.1–24 h.

[0042] Optionally, the upper limit of the reduction temperature can be independently selected from 800℃, 700℃, 550℃, 480℃, 390℃, 310℃, 240℃, 170℃, and 130℃; the lower limit can be independently selected from 100℃, 150℃, 200℃, 280℃, 350℃, 420℃, 500℃, 590℃, 650℃, 710℃, and 750℃.

[0043] Optionally, the upper limit of the restoration time can be independently selected from 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, and 24h; the lower limit can be independently selected from 0.1h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, and 22h.

[0044] Optionally, the reducing atmosphere is one of hydrogen, a hydrogen-argon mixture, or a hydrogen-nitrogen mixture, wherein the volume percentage of hydrogen in the mixture is ≥1%.

[0045] Optionally, the hydrogen volume percentage in the mixture is 1% to 100%.

[0046] Optionally, the upper limit of the volume percentage of hydrogen in the mixture can be independently selected from 100%, 87%, 72%, 63%, 54%, 46%, 33%, 25%, 19%, 8%, or 5%; the lower limit can be independently selected from 1%, 6%, 15%, 23%, 35%, 42%, 56%, 65%, 73%, 84%, or 96%.

[0047] In one specific embodiment, the preparation method involves precipitating rare earth metal salts and the active component ruthenium precursor onto the surface of a metal oxide support via a one-step co-precipitation method, followed by reduction to obtain the rare earth oxide-modified oxide-supported ruthenium catalyst. The method specifically includes the following steps:

[0048] (1) Preparation of catalyst precursor: The support is added to the precipitant solution and stirred evenly to obtain a suspension. Then, under stirring, a mixed solution of ruthenium precursor and rare earth metal salt is added to the above suspension and reacted at room temperature for 0.1 to 48 h to obtain the catalyst precursor.

[0049] (2) Catalyst precursor reduction: The obtained catalyst precursor is reduced in a reducing atmosphere at 100-800℃ for 0.1-24h to obtain the rare earth oxide modified oxide supported ruthenium catalyst.

[0050] In another aspect of this application, a supported ruthenium-based catalyst obtained according to the above preparation method is provided, and at least one of the above-mentioned supported ruthenium-based catalysts is used in an ammonia synthesis reaction; the supported ruthenium-based catalyst is used in the ammonia synthesis reaction to catalyze the synthesis of ammonia from hydrogen and nitrogen.

[0051] Optionally, the supported ruthenium-based catalyst is mixed with a mixed atmosphere containing nitrogen and hydrogen to carry out an ammonia synthesis reaction to obtain ammonia.

[0052] The supported ruthenium-based catalyst prepared by the method described in this application has rare earth oxide promoters in an atomically dispersed state on the catalyst surface, which can suppress the poisoning effect of hydrogen on the supported ruthenium catalyst and significantly improve the catalyst's ammonia synthesis activity.

[0053] Optionally, in the mixed atmosphere, the volume ratio of nitrogen to hydrogen is 1:3 to 3:1, the reaction temperature is 350 to 400°C, the reaction pressure is 0.1 to 5.0 MPa, and the gas hourly space velocity is 1000 to 50000 mL g. -1 h -1 .

[0054] Optionally, the upper limit of the volume ratio of nitrogen to hydrogen can be independently selected from 1:1, 2:1, or 3:1; the lower limit can be independently selected from 1:3, 1:1, or 2:1.

[0055] Optionally, the upper limit of the reaction temperature can be independently selected from 360℃, 370℃, 380℃, 390℃, and 400℃; the lower limit can be independently selected from 350℃, 360℃, 370℃, 380℃, and 390℃.

[0056] Optionally, the upper limit of the reaction pressure can be independently selected from 0.5MPa, 1MPa, 2MPa, 3MPa, 4MPa, and 5MPa; the lower limit can be independently selected from 0.1MPa, 0.5MPa, 1MPa, 2MPa, 3MPa, and 4MPa.

[0057] Optionally, the upper limit of the gas space velocity for the reaction can be independently selected from 5000 mL g. -1 h -1 10000mL g -1 h -1 20000mL g -1 h -1 24000mL g -1 h -1 30000mL g -1 h -1 40000mL g -1 h -1 50000mL g -1 h -1 The lower limit can be independently selected from 1000 mL g. -1 h -1 5000mL g -1 h -1 10000mL g -1 h -120000mL g -1 h -1 24000mL g -1 h -1 30000mL g -1 h -1 40000mL g -1 h -1 .

[0058] Optionally, the supported ruthenium-based catalyst is heated in a mixed atmosphere at 1–20 °C / min. -1 The temperature is raised to the reduction temperature of 300–800℃, and after reduction at the reduction temperature for 0.5–20 h, the temperature is lowered to the reaction temperature of 350–400℃ to carry out the ammonia synthesis reaction.

[0059] Optionally, the upper limit of the heating rate can be independently selected from 20°C / min. -1 19℃min -1 15℃min -1 13℃min -1 10℃min -1 9℃min -1 6℃min -1 5℃min -1 2℃min -1 The lower limit can be independently selected from 1℃ min. -1 2℃min -1 5℃min -1 6℃min -1 9℃min -1 10℃min -1 13℃min -1 15℃min -1 19℃min -1 、;

[0060] Optionally, the upper limit of the reduction temperature can be independently selected from 800℃, 700℃, 600℃, 500℃, 350℃, and the lower limit can be independently selected from 300℃, 400℃, 550℃, 650℃, 750℃, and so on.

[0061] Optionally, the upper limit of the restoration time can be independently selected from 20h, 16h, 12h, 7h, and 2h; the lower limit can be independently selected from 0.5h, 3h, 8h, 13h, and 19h.

[0062] Unless otherwise specified, all figures appearing in this application specification and claims, such as active components, temperature, time, pressure, etc., should not be construed as absolutely precise values. Due to the standard deviation of measurement techniques, the measured values ​​inevitably contain a certain degree of experimental error.

[0063] The atomically dispersed rare earth oxide-modified oxide-supported ruthenium catalyst for ammonia synthesis described in this application has the advantages of high activity, good stability, and resistance to hydrogen poisoning. Compared with the prior art, the beneficial effects of the ruthenium-based catalyst provided in this application include:

[0064] (1) Compared with traditional metal oxide (alumina, magnesium oxide, silicon oxide, etc.) supported ruthenium nanoparticle catalysts, the atomically dispersed rare earth oxide additive modified oxide supported ruthenium catalysts provided in this application have higher catalytic activity.

[0065] (2) The atomically dispersed rare earth oxide additive modified oxide supported ruthenium ammonia synthesis catalyst provided in this application has good stability, and no significant change in activity was observed during the 160-hour test.

[0066] (3) The raw materials used in the preparation method of the catalyst provided in this application, such as metal oxides, ruthenium salts, rare earth salts and precipitants, are all bulk chemicals with relatively low cost.

[0067] (4) The preparation method provided in this application has the advantages of simple and safe preparation process, and is easy to achieve large-scale preparation. Attached Figure Description

[0068] Figure 1 This is a high-angle annular dark-field scanning transmission electron microscope (STEM) elemental image of the catalyst after Ce-3%Ru(1:1) / Al2O3 reduction in Example 1 of this application.

[0069] Figure 2 The figure shows the 160-h stability test results of the catalyst after Ce-3%Ru(1:1) / Al2O3 reduction in Example 1.

[0070] Figure 3 The images show different pressure-activity curves of the catalysts after reduction of Ce-3%Ru(1:1) / Al2O3 in Example 1 and 3%Ru / Al2O3 in Comparative Example 1. Detailed Implementation

[0071] As mentioned above, this application relates to a one-step coprecipitation method for preparing rare earth oxide-modified oxide-supported ruthenium catalyst with excellent catalytic activity and stability, and its application in the ammonia synthesis reaction.

[0072] The present application is described in detail below with reference to embodiments, but is not limited to the embodiments described. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0073] In the embodiments of this application, the ammonia synthesis reaction is carried out on a fixed-bed microreactor using a stainless steel reactor. The composition of the reaction gas is analyzed by a conductivity meter, and the reaction tail gas is passed into a dilute sulfuric acid solution. At the same time, the conductivity meter is used to track the change in conductivity, and finally the ammonia generation rate is calculated based on the conductivity parameters.

[0074] The conductivity meter was a METTLLER TOLEDO instrument manufactured by Qixing, model S230-K-CN. The aberration-corrected transmission electron microscope was model JEOL-JEM2100F, and the high-resolution transmission electron microscope was model JEM-2100, used to observe the elemental distribution of the catalyst.

[0075] Example 1

[0076] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.064 g of cerium nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution under stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0077] Figure 1 High-resolution transmission electron microscopy characterization results show that Ru in the above Ce-3%Ru(1:1) / Al2O3 catalyst exhibits a highly dispersed state with an average size of 1.8 nm. Figure 1 High-angle annular dark-field scanning transmission electron microscopy (EDX-Mapping) elemental imaging analysis results show that Ce species in Ce-3%Ru(1:1) / Al2O3 catalyst are atomically dispersed and mostly aggregated around ruthenium nanoparticles.

[0078] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 15653 μmol g under the reaction conditions. - 1 h -1 The ammonia production rate at 350℃ was 5634 μmol g. -1 h -1 .

[0079] Example 2

[0080] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.032 g of cerium nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 80 °C. The dried product was reduced at 650 °C for 2 h in a 10% hydrogen-argon mixed atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(0.5:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0081] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 14987 μmol g under the reaction conditions. - 1 h -1 The ammonia production rate at 350℃ is 5534 μmol g. -1 h -1 .

[0082] Example 3

[0083] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.016 g of cerium nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution under stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a 50% hydrogen-nitrogen mixed atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(0.3:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0084] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 1°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1The ammonia production rate at 400℃ was measured to be 7952 μmol g under the reaction conditions. - 1 h -1 .

[0085] Example 4

[0086] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.008 g of cerium nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(0.1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0087] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 20°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 3123 μmol g under the reaction conditions. -1 h -1 .

[0088] Example 5

[0089] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 10.0 g of potassium carbonate and stirred until homogeneous. 0.068 g of ruthenium chloride and 0.540 g of cerium nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a 90% hydrogen-argon mixed atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-5%Ru(5:1) / Al2O3) with a ruthenium loading of 5 wt.%.

[0090] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 300℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1h -1 The ammonia production rate at 400℃ was measured to be 18793 μmol g under the reaction conditions. - 1 h -1 .

[0091] Example 6

[0092] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 1.0 g of potassium carbonate and stirred until homogeneous. 0.014 g of ruthenium chloride and 0.200 g of cerium nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution under stirring. The precipitation reaction was carried out at 20 °C for 24 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a 1 wt.% ruthenium oxide-promoted alumina-supported ruthenium catalyst (Ce-1%Ru(9:1) / Al2O3).

[0093] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:1 at 5°C for 1 minute. -1 The temperature was raised to 800℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 8876 μmol g under the reaction conditions. - 1 h -1 .

[0094] Example 7

[0095] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.141 g of ruthenium nitrite nitrite and 0.064 g of cerium nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. While stirring, the mixed solution of ruthenium chloride and cerium nitrate was added to the aqueous solution of the support. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a 9 wt.% ruthenium oxide-promoted alumina-supported ruthenium catalyst (Ce-9%Ru(1:1) / Al2O3).

[0096] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 25°C for 1 minute. -1The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 5 MPa and a gas hourly space velocity of 50,000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 14536 μmol / g under the reaction conditions. -1 h -1 .

[0097] Example 8

[0098] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.006 g of potassium ruthenate and 0.064 g of cerium nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. While stirring, the mixed solution of ruthenium chloride and cerium nitrate was added to the support aqueous solution. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a 30% hydrogen-nitrogen mixed atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-0.5%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0099] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 0.5 h, then lowered to 400℃. The reaction was carried out at a pressure of 2 MPa and a gas hourly space velocity of 2000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 13452 μmol g under the reaction conditions. -1 h -1 .

[0100] Example 9

[0101] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 2.5 g of potassium carbonate and stirred until homogeneous. 0.063 g of ruthenium acetylacetone and 0.064 g of ruthenium chloride were dissolved in 20 mL of water to form a solution. While stirring, a mixed solution of ruthenium chloride and cerium nitrate was added to the support aqueous solution. The precipitation reaction was carried out at 20 °C for 48 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a 3 wt.% ruthenium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(1:1) / Al2O3).

[0102] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 11325 μmol g under the reaction conditions. - 1 h -1 .

[0103] Example 10

[0104] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.01 g of sodium hydroxide and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.037 g of cerium chloride were weighed and dissolved in 20 mL of water to form a solution. The mixed solution of ruthenium chloride and cerium nitrate was added to the aqueous solution of the support while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 750 °C for 0.2 h in a hydrogen atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0105] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 9876 μmol g under the reaction conditions. - 1 h -1 .

[0106] Example 11

[0107] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.3 g of potassium hydroxide and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.085 g of cerium sulfate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution under stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a 30% hydrogen-argon mixed atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0108] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 2:1 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 20 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 12092 μmol g under the reaction conditions. - 1 h -1 .

[0109] Example 12

[0110] 0.5 g of alumina support was dispersed in 50 mL of an aqueous solution containing 0.1 g of sodium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.048 g of cerium acetate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 250 °C for 12 h in a hydrogen atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0111] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 6754 μmol g under the reaction conditions. - 1 h -1 .

[0112] Example 13

[0113] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.2 mL of ammonia and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.064 g of cerium nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 350 °C for 6 h in a hydrogen atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0114] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 10987 μmol g under the reaction conditions. - 1 h -1 .

[0115] Example 14

[0116] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.5 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.064 g of lanthanum nitrate hexahydrate were weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride and lanthanum nitrate solution was added to the support aqueous solution under stirring. The precipitation reaction was carried out at 20 °C for 0.5 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 150 °C for 24 h in a 66% hydrogen-nitrogen mixed atmosphere to obtain a lanthanum oxide-promoted alumina-supported ruthenium catalyst (La-3%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0117] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 9600 μmol g under the reaction conditions. - 1 h -1 .

[0118] Example 15

[0119] 0.5 g of alumina support was dispersed in an aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.056 g of yttrium nitrate hexahydrate were weighed and dissolved in 50 mL of water to form a solution. The ruthenium chloride and yttrium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a 3 wt.% yttrium oxide-promoted alumina-supported ruthenium catalyst (Y-3%Ru(1:1) / Al2O3).

[0120] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 3:1 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 12134 μmol g under the reaction conditions. - 1 h -1 .

[0121] Example 16

[0122] 0.5 g of alumina support was dispersed in an aqueous solution containing 0.8 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.068 g of samarium nitrate hexahydrate were weighed and dissolved in 50 mL of water to form a solution. The ruthenium chloride and samarium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 21 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 400 °C for 5 h in a hydrogen atmosphere to obtain a samarium oxide-promoted alumina-supported ruthenium catalyst (Sm-3%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0123] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 7910 μmol g under the reaction conditions. - 1 h -1 .

[0124] Example 17

[0125] 0.5 g of alumina support was dispersed in an aqueous solution containing 0.4 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.067 g of europium nitrate hexahydrate were weighed and dissolved in 50 mL of water to form a solution. The ruthenium chloride and europium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 5 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 650 °C for 4 h in a hydrogen atmosphere to obtain a ruthenium oxide-supported alumina catalyst (Eu-3%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0126] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 4684 μmol g under the reaction conditions. - 1 h -1 .

[0127] Example 18

[0128] 0.5 g of magnesium oxide support was dispersed in an aqueous solution containing 0.9 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.064 g of cerium nitrate hexahydrate were weighed and dissolved in 50 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 10 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 500 °C for 1 h in a hydrogen atmosphere to obtain a cerium oxide-promoted magnesium oxide-supported ruthenium catalyst (Ce-3%Ru(1:1) / MgO) with a ruthenium loading of 3 wt.%.

[0129] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 21050 μmol g under the reaction conditions. - 1 h -1 .

[0130] Example 19

[0131] 0.5 g of silica support was dispersed in an aqueous solution containing 1.5 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.064 g of cerium nitrate hexahydrate were weighed and dissolved in 50 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution under stirring. The precipitation reaction was carried out at 20 °C for 8 h. After filtration, the product was washed with deionized water until the solution was neutral and then dried in an oven at 60 °C. The dried product was reduced at 350 °C for 4 h in a hydrogen atmosphere to obtain a cerium oxide-promoted silica-supported ruthenium catalyst (Ce-3%Ru(1:1) / SiO2) with a ruthenium loading of 3 wt.%.

[0132] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 8980 μmol g under the reaction conditions. - 1 h -1 .

[0133] Example 20

[0134] 0.5 g of titanium dioxide support was dispersed in an aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.064 g of cerium nitrate hexahydrate were weighed and dissolved in 50 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution under stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a cerium-promoted titanium dioxide supported ruthenium catalyst (Ce-3%Ru(1:1) / TiO2) with a ruthenium loading of 3 wt.%.

[0135] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 6540 μmol g under the reaction conditions. - 1 h -1 .

[0136] Example 21

[0137] 0.5 g of zirconium oxide support was dispersed in an aqueous solution containing 0.2 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride and 0.064 g of cerium nitrate hexahydrate were weighed and dissolved in 50 mL of water to form a solution. The ruthenium chloride and cerium nitrate solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a cerium oxide-promoted zirconium oxide supported ruthenium catalyst (Ce-3%Ru(1:1) / ZrO2) with a ruthenium loading of 3 wt.%.

[0138] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 8820 μmol g under the reaction conditions. - 1 h -1 .

[0139] Comparative Example 1

[0140] 0.5 g of alumina support was dispersed in an aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride was dissolved in 50 mL of water to form a solution. The ruthenium chloride solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain an alumina-supported ruthenium catalyst (3% Ru / Al₂O₃) with a ruthenium loading of 3 wt.%.

[0141] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 1435 μmol g under the reaction conditions. - 1 h -1 .

[0142] Comparative Example 2

[0143] 0.5 g of magnesium oxide support was dispersed in an aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride was dissolved in 50 mL of water to form a solution. The ruthenium chloride solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a magnesium oxide-supported ruthenium catalyst (3% Ru / MgO) with a ruthenium loading of 3 wt.%.

[0144] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 2343 μmol g under the reaction conditions. - 1 h -1 .

[0145] Comparative Example 3

[0146] 0.5 g of silica support was dispersed in an aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride was dissolved in 50 mL of water to form a solution. The ruthenium chloride solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a silica-supported ruthenium catalyst (3% Ru / SiO2) with a ruthenium loading of 3 wt.%.

[0147] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 567 μmol g under the reaction conditions. -1 h -1 .

[0148] Comparative Example 4

[0149] 0.5 g of titanium dioxide support was dispersed in an aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride was dissolved in 50 mL of water to form a solution. The ruthenium chloride solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a titanium dioxide-supported ruthenium catalyst (3% Ru / TiO2) with a ruthenium loading of 3 wt.%.

[0150] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 1098 μmol g under the reaction conditions. - 1 h -1 .

[0151] Comparative Example 5

[0152] 0.5 g of zirconium oxide support was dispersed in an aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride was dissolved in 50 mL of water to form a solution. The ruthenium chloride solution was added to the support aqueous solution while stirring. The precipitation reaction was carried out at 20 °C for 2 h. The mixture was then filtered, and the product was washed with deionized water until the solution was neutral. The product was then dried in an oven at 60 °C. The dried product was reduced at 450 °C for 2 h under a hydrogen atmosphere to obtain a zirconium oxide-supported ruthenium catalyst (3% Ru / ZrO2) with a ruthenium loading of 3 wt.%.

[0153] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 976 μmol g under the reaction conditions. -1 h -1 .

[0154] Comparative Example 6

[0155] 0.5 g of alumina support was dispersed in 50 mL of aqueous solution containing 0.1 g of potassium carbonate and stirred until homogeneous. 0.041 g of ruthenium chloride was weighed and dissolved in 20 mL of water to form a solution. The ruthenium chloride solution was added to the support aqueous solution while stirring, and the precipitation reaction was carried out at 20 °C for 2 h. After filtration, the product was washed with deionized water until the solution was neutral, and then dried in an oven at 60 °C. The dried product was calcined at 400 °C for 2 h in a hydrogen atmosphere. Then, 0.064 g of cerium nitrate hexahydrate was impregnated onto the catalyst surface. The dried product was reduced at 450 °C for 2 h in a hydrogen atmosphere to obtain a cerium oxide-promoted alumina-supported ruthenium catalyst (Ce-3%Ru(1:1) / Al2O3) with a ruthenium loading of 3 wt.%.

[0156] The reaction performance of the prepared catalyst was evaluated in an ammonia synthesis unit by reacting the catalyst in a nitrogen-hydrogen mixture with a volume ratio of 1:3 at 5°C for 1 minute. -1 The temperature was raised to 450℃ and reduced at this temperature for 10 hours, then lowered to 400℃. The reaction was carried out at a pressure of 1 MPa and a gas hourly space velocity (GHSV) of 24000 mL / g. -1 h -1 The ammonia production rate at 400℃ was measured to be 6954 μmol g under the reaction conditions. - 1 h -1 .

[0157] Based on the ammonia synthesis catalytic performance results of the rare earth oxide-promoted supported ruthenium catalyst samples in Table 1, a comparison of the results between Examples 1, 2, 3, and 4 shows that the amount of cerium oxide promoter has a significant impact on the catalyst. The optimal modification effect is achieved when the molar ratio of cerium oxide promoter to metallic ruthenium is 1:1. Compared with Comparative Example 6, the cerium oxide-promoted alumina-supported ruthenium catalyst prepared by the one-step co-precipitation method in this application exhibits higher catalytic activity than the conventional stepwise method.

[0158] The stability of the Ce-3%Ru(1:1) / Al2O3 catalyst from Example 1 above was tested in an ammonia synthesis unit. The cerium oxide-promoted alumina-supported ruthenium catalyst prepared in this application exhibited high stability, and its activity remained unchanged after 160 hours of reaction (see...). Figure 2 Furthermore, the Ce-3%Ru(1:1) / Al2O3 catalyst of this patent application exhibits a significantly positive hydrogen response and higher resistance to hydrogen poisoning compared to Comparative Example 1 (see...). Figure 3 ).

[0159] Table 1 Comparison of ammonia synthesis activities of different catalysts

[0160]

[0161]

[0162] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A supported ruthenium-based catalyst, characterized in that, The supported ruthenium-based catalyst comprises a metal oxide support, an active component, and a rare earth oxide promoter; The metal oxide support is selected from one or more of aluminum oxide, magnesium oxide, silicon oxide, titanium oxide, and zirconium oxide; The active component includes an active element, which is ruthenium; The additive is a rare earth oxide; The rare earth elements in the rare earth oxides are in an atomically dispersed state. The catalyst is prepared by a one-step coprecipitation method, wherein the metal oxide support is mixed with a solution containing a precipitant, and then a mixed solution containing a ruthenium precursor and a rare earth metal salt is added. The mixture is reacted at 10°C to 50°C for 0.1 to 48 hours, and then reduced in a reducing atmosphere at 100°C to 800°C for 0.1 to 24 hours.

2. The supported ruthenium-based catalyst according to claim 1, characterized in that, The rare earth oxides are selected from one or more of cerium oxide, scandium oxide, yttrium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, and lutetium oxide; In the supported ruthenium-based catalyst, The mass of the active component is 0.1% to 10% of the mass of the metal oxide support, wherein the mass of the active component is calculated based on the mass of the active element; The molar ratio of the auxiliary agent to the active component is 0.1:1 to 10:1, wherein the number of moles of the auxiliary agent is calculated in terms of the number of moles of rare earth elements, and the number of moles of the active component is calculated in terms of the number of moles of active elements.

3. The supported ruthenium-based catalyst according to claim 1, characterized in that, The rare earth elements in the rare earth metal salt are selected from at least one of cerium, scandium, yttrium, lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. The rare earth metal salt is selected from one or more of the rare earth chlorides, rare earth nitrates, rare earth acetates, and rare earth sulfates corresponding to rare earth elements.

4. The supported ruthenium-based catalyst according to claim 1, characterized in that, The ruthenium precursor is selected from at least one ruthenium salt; The ruthenium salt is selected from one or more of ruthenium chloride, ruthenium nitrite, ruthenium acetylacetone, and potassium ruthenate; The precipitant is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, cesium hydroxide, sodium carbonate, potassium carbonate, and cesium carbonate.

5. The supported ruthenium-based catalyst according to claim 1, characterized in that, The molar ratio of the precipitant to the ruthenium precursor is 1:1 to 400:1, wherein the amount of the precipitant is calculated based on the amount of the precipitant itself, and the amount of the ruthenium precursor is calculated based on the amount of ruthenium in the precursor.

6. The supported ruthenium-based catalyst according to claim 5, characterized in that, The molar ratio of the rare earth metal salt to the ruthenium precursor is 0.1:1 to 10:1, wherein the molar amount of the rare earth metal salt is calculated based on the amount of rare earth element, and the amount of the ruthenium precursor is calculated based on the amount of ruthenium element in the precursor.

7. The supported ruthenium-based catalyst according to claim 5, characterized in that, The mass ratio of the metal oxide support to the ruthenium precursor is 10:1 to 100:1, wherein the mass of the metal oxide support is calculated based on the mass of the metal oxide, and the mass of the ruthenium precursor is calculated based on the mass of the ruthenium element.

8. The supported ruthenium-based catalyst according to claim 1, characterized in that, The reducing atmosphere is one of hydrogen, a hydrogen-argon mixture, or a hydrogen-nitrogen mixture. The volume percentage of hydrogen in the mixture is 1% to 100%, excluding the endpoint value of 100%.

9. The application of the supported ruthenium-based catalyst according to any one of claims 1-8 in the ammonia synthesis reaction.

10. The application according to claim 9, characterized in that, The supported ruthenium-based catalyst was mixed with a mixed atmosphere containing nitrogen and hydrogen to carry out an ammonia synthesis reaction, thereby obtaining ammonia. In the mixed atmosphere, the volume ratio of nitrogen to hydrogen is 1:3 to 3:1, the reaction temperature is 350 to 400 °C, the reaction pressure is 0.1 to 5.0 MPa, and the gas hourly space velocity (GHSV) is 1000 to 50000 mL g. -1 h -1 ; The supported ruthenium-based catalyst was subjected to a mixed atmosphere at a temperature of 1°C to 20°C per minute. -1 The temperature is raised to the reduction temperature of 300~800℃, and after reduction at the reduction temperature for 0.5 h~20 h, the temperature is lowered to the reaction temperature of 350~400℃ to carry out the ammonia synthesis reaction.

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