Samarium-based catalyst for ortho-parahydrogen conversion as well as preparation method and application of samarium-based catalyst

Abstract

The invention relates to a samarium-based catalyst for ortho-parahydrogen conversion and a preparation method and application thereof.The samarium-based catalyst comprises a main component and auxiliaries, the main component comprises samarium oxide, and the auxiliaries comprise a first auxiliary and a second auxiliary; the first auxiliary agent comprises an oxide containing metal M1; the metal M1 comprises any one or a combination of at least two of cobalt, nickel or gallium; the second auxiliary agent comprises an oxide containing metal M2; the metal M2 comprises manganese and / or zinc. The samarium-based catalyst provided by the invention has the advantages of excellent catalytic performance, good stability and high conversion rate in ortho-parahydrogen conversion reaction, a samarium element is adopted to replace a main component iron element in a conventional ortho-parahydrogen conversion catalyst, a new thought is created, and a more excellent catalytic effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a samarium-based catalyst for ortho-parahydrogen conversion and a preparation method and application thereof. Background Art

[0002] In the research field of ortho-parahydrogen conversion catalysts, liquid hydrogen, as a high-energy fuel, has important application value in the fields of aerospace, defense industry, etc. Liquid hydrogen is mainly composed of orthohydrogen with the same nucleus spin direction and parahydrogen with opposite spin directions, and its equilibrium content is closely related to temperature. Under room temperature conditions, orthohydrogen accounts for about 75% and parahydrogen accounts for about 25%. As the temperature decreases, orthohydrogen will spontaneously convert to parahydrogen and release heat. This spontaneous conversion process will cause the liquid hydrogen to gasify, thereby increasing the evaporation loss of liquid hydrogen. Therefore, in the process of hydrogen liquefaction, an ortho-parahydrogen conversion catalyst is needed to promote the conversion of orthohydrogen to parahydrogen and reduce the evaporation loss of liquid hydrogen.

[0003] CN117943001A discloses a parahydrogen conversion catalyst with iron oxide as the core, using adsorption layer technology to precipitate an iron oxide layer on the surface of other oxides in a water-organic two-phase solution of an alkaline reagent and an iron salt. Through this preparation method, a series of Fe, Fe@SiO2, Fe@TiO2, and Fe@Al2O3 parahydrogen conversion catalysts prepared all have high mechanical strength and excellent catalytic performance.

[0004] CN115155583A discloses an electric-loaded parahydrogen conversion catalyst and a preparation method thereof. The catalyst composition includes an activated carbon carrier and metal oxides such as Fe. The preparation method of the catalyst includes the following steps: S1. Electroplating the metal inside the activated carbon pores by electrodeposition; S2. Oxidizing the metal inside the activated carbon pores to form metal oxides loaded in the activated carbon to prepare parahydrogen conversion catalyst powder; S3. Mixing the parahydrogen conversion catalyst powder with ultrafine sodium chloride powder, bonding with an anhydrous binder to form granules, and then drying, soaking in water, and drying again to obtain the parahydrogen conversion catalyst. The parahydrogen conversion catalyst prepared by the method has the advantages of adjustable particle size, not easy to pulverize, good catalytic effect, and low cost.

[0005] CN118079978A discloses an iron-based parahydrogen conversion catalyst, a preparation method and an application thereof, wherein the catalyst uses Ni and Mg to treat alumina, and then uses the treated alumina as a carrier, and an impregnation liquid made of Fe and an additive is impregnated on the carrier to prepare the iron-based parahydrogen conversion catalyst. The parahydrogen conversion catalyst prepared by the method has high dispersion, avoids the problem of pulverization and loss of traditional hydrated iron oxide catalysts, has excellent comprehensive performance, and significantly improves the flow resistance of the catalyst bed under the parahydrogen conversion working condition.

[0006] As the most common catalyst for the conversion of para-hydrogen, iron-based catalysts have stable activity and better performance than other metal oxides (Cu, Ti, etc.). At present, the most widely used commercial catalyst for the conversion of para-hydrogen is the iron-based catalyst produced by Molecular Corporation in the United States. The catalyst is 1.36 bar, 77 K, and a gas phase space velocity of 1200 ml min -1 mlcat -1 Under the reaction conditions of 75% orthohydrogen and 25% parahydrogen as the inlet gas composition, a higher parahydrogen concentration can be achieved. However, due to the influence of the structure and preparation process of the iron-based catalyst itself, there is little room for further improvement in its performance.

[0007] Therefore, providing a non-iron-based catalyst with excellent catalytic performance and good stability for use in the ortho-parahydrogen conversion reaction has become a technical problem that needs to be solved urgently. Summary of the invention

[0008] In order to solve the above technical problems, the purpose of the present invention is to provide a samarium-based catalyst for ortho-parahydrogen conversion and its preparation method and application. The samarium-based catalyst provided by the present invention has the advantages of excellent catalytic performance, good stability and high conversion rate for ortho-parahydrogen conversion reaction. The samarium element is used to replace the main component iron element in the conventional ortho-parahydrogen conversion catalyst, which opens up a new idea and achieves a more excellent catalytic effect.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a samarium-based catalyst for normal-parahydrogen conversion, the samarium-based catalyst comprising a main component and an auxiliary agent, the main component comprising samarium oxide, the auxiliary agent comprising a first auxiliary agent and a second auxiliary agent;

[0011] The first additive includes an oxide containing a metal M1; the metal M1 includes any one of cobalt, nickel or gallium or a combination of at least two thereof;

[0012] The second auxiliary agent includes an oxide containing a metal M2; the metal M2 includes manganese and / or zinc.

[0013] The samarium-based catalyst provided by the present invention uses samarium oxide as the main active component. The samarium element has a high electron affinity and a rich 4f electronic structure, and has more unpaired electrons, so it has a strong spin magnetism. At the same time, the 4f electrons of the samarium element have good delocalization performance, and are easy to contact with H2 molecules to form interactions, effectively adsorb and activate molecules, and enhance the adsorption capacity of orthohydrogen molecules, thereby promoting the conversion effect of orthohydrogen to parahydrogen. In addition, the samarium element can also stabilize the structure of the catalyst, improve the thermal stability and mechanical strength of the catalyst, which is crucial for maintaining the long-term catalytic stability of the catalyst under harsh operating conditions. Cobalt, nickel or gallium oxide as the first auxiliary agent can play the role of a promoter. Cobalt, nickel and gallium metal elements have high catalytic activity and good electronic spin characteristics. They can form a bimetallic oxide structure with samarium elements, improve the spin of electrons in samarium-based catalysts, and accelerate the dissociation of hydrogen molecules and the recombination of H nuclei, optimize the diffusion path of hydrogen molecules on the catalyst surface, and promote the heterotropic spin recombination of two dissociated H nuclei under the induction of high electron spin, thereby improving the efficiency of the conversion of orthohydrogen to parahydrogen. Manganese or zinc oxide is used as the second auxiliary agent of the catalyst, that is, the structural auxiliary agent, which can optimize the structure of the catalyst and adjust the active sites, promote the formation of oxygen vacancies on the catalyst surface, and enhance the adsorption of hydrogen molecules; at the same time, it plays a dispersing role, improving the dispersion of the main active component samarium oxide and the first auxiliary agent, and avoiding the agglomeration of active components during long-term operation; in addition, the second auxiliary agent has a strong water absorption property, and the trace water present in the raw gas of the ortho-parahydrogen reaction will be preferentially adsorbed on the second auxiliary agent, thereby protecting the main active component and the first auxiliary agent, and greatly improving the service life of the catalyst.

[0014] The samarium-based catalyst provided by the present invention uses samarium oxide as the main component, uses cobalt, nickel or gallium oxide as the first auxiliary agent, and uses manganese or zinc oxide as the second auxiliary agent. The main component and the first and second auxiliary agents cooperate with each other, which can improve the catalytic performance and catalytic stability of the samarium-based catalyst, and has a high conversion rate for catalyzing the normal-parahydrogen conversion reaction. The present invention uses samarium element to replace the main component iron element in the conventional normal-parahydrogen conversion catalyst, which opens up a new idea and achieves a more excellent catalytic effect.

[0015] Preferably, based on the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar percentage of the samarium element is 40-90 mol%, for example, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol% or 90 mol%, etc.

[0016] In the samarium-based catalyst provided by the present invention, if the content of samarium element is too high, too much samarium oxide will be formed in the catalyst, resulting in the formation of SmO on the catalyst surface. x A thin layer covers the active sites, reducing the effective adsorption of orthohydrogen and parahydrogen, thereby reducing the activity of the catalyst; if the samarium content is too low, it is not enough to provide sufficient active sites, affecting the conversion efficiency of orthohydrogen to parahydrogen, resulting in a decrease in catalytic performance.

[0017] Preferably, based on the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar percentage of the metal M1 is 5-30 mol%, for example, 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol% or 30 mol%.

[0018] In the samarium-based catalyst provided by the present invention, if the content of the metal M1 element of the first auxiliary agent is too high, it will compete with the samarium element for active sites, affect the adsorption and activation ability of the samarium element, and thus reduce the overall performance of the catalyst; if the content of the metal M1 element of the first auxiliary agent is too low, it will cause the electronic spin and catalytic activity of the catalyst to decrease, and the content of cobalt, nickel or gallium metal elements that is too low is insufficient to form an efficient bimetallic oxide structure with samarium oxide, affecting the rate at which the catalyst converts normal and para-hydrogen.

[0019] Preferably, based on the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar percentage of the metal M2 is 5-30 mol%, for example, 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol% or 30 mol%.

[0020] In the samarium-based catalyst provided by the present invention, if the content of the metal M2 element of the second auxiliary agent is too high, the redox properties of the catalyst will be changed, affecting its ability to activate orthohydrogen molecules; if the content of the metal M2 element of the second auxiliary agent is too low, the proportion of the structural auxiliary agent manganese or zinc metal elements will be reduced, and the selective adsorption of water and the good dispersion of the active components cannot be achieved, thereby reducing the stability of the catalyst.

[0021] In a second aspect, the present invention provides a method for preparing the samarium-based catalyst according to the first aspect, the preparation method comprising the following steps:

[0022] (1) mixing a samarium source, an M1 metal source, an M2 metal source and a solvent to obtain a precursor solution;

[0023] The M1 metal source includes any one of a cobalt source, a nickel source or a gallium source, or a combination of at least two thereof;

[0024] The M2 metal source includes a manganese source and / or a zinc source;

[0025] (2) subjecting the precursor solution and the precipitant to a coprecipitation reaction, and separating them to obtain the samarium-based catalyst.

[0026] In the preparation method of the catalyst provided by the present invention, the addition of samarium source in the raw material can introduce samarium oxide into the catalyst, and the samarium element can effectively adsorb and activate H2 molecules, promote the conversion of orthohydrogen molecules into parahydrogen molecules, and is the main active component; the addition of cobalt, nickel or gallium metal sources introduces corresponding metal elements into the catalyst, which can eventually form a bimetallic oxide effect with the main active component samarium Sm element, enhance the mechanical strength of the catalyst, and promote the generation of more catalytic active centers on the surface, enhance the electron spin on the catalyst surface, optimize the diffusion path of molecules on the catalyst surface, and improve the catalytic rate; the addition of manganese or zinc substances introduces corresponding metal elements into the obtained catalyst, which can serve as a structural additive, mainly play the role of dispersing the active components of the catalyst, and inhibit the agglomeration of the active components of the catalyst under long-term operation. At the same time, the manganese or zinc metal elements can also play the role of H2O sacrificial agent, and can adsorb trace H2O in the reaction raw gas, thereby greatly improving the stability of the catalyst.

[0027] The present invention uses a samarium source as raw material and mixes it with a cobalt source, a nickel source or a gallium source, and a manganese source and / or a zinc source, and combines it with a precipitant to carry out a coprecipitation reaction process, thereby obtaining a samarium-based catalyst with uniform active site distribution, stable structure, high mechanical strength, strong catalytic activity, and excellent catalytic performance and catalytic rate. The preparation process is simple, easy to operate, and has a low preparation cost, and is suitable for industrial production of samarium-based catalysts.

[0028] Preferably, based on the total molar amount of metal elements in the precursor solution in step (1) as 100 mol%, the molar percentage of the samarium element is 40-90 mol%, for example, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol% or 90 mol%, etc.

[0029] Preferably, based on the total molar amount of metal elements in the precursor solution in step (1) as 100 mol%, the molar percentage of the M1 metal element is 5-30 mol%, for example, 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol% or 30 mol%.

[0030] Preferably, taking the total molar amount of metal elements in the precursor solution in step (1) as 100 mol%, the molar percentage of the M2 metal element is 5-30 mol%, for example, 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol% or 30 mol%, etc.

[0031] Preferably, the total molar concentration of the metal elements in the precursor solution in step (1) is 0.5-5 mol / L, for example 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L.

[0032] In the present invention, the total concentration of metal elements in the precursor solution can affect the particle size of the catalyst crystals and the dispersion of the active components, thereby affecting the catalytic performance of the ultimately obtained samarium-based catalyst.

[0033] Preferably, the samarium source includes any one of samarium nitrate, samarium acetate or samarium chloride, or a combination of at least two of them.

[0034] Preferably, the cobalt source includes any one of cobalt nitrate, cobalt acetate or cobalt chloride, or a combination of at least two of them.

[0035] Preferably, the nickel source includes any one of nickel nitrate, nickel acetate or nickel chloride, or a combination of at least two of them.

[0036] Preferably, the gallium source includes any one of gallium nitrate, gallium acetate or gallium chloride, or a combination of at least two of them.

[0037] Preferably, the manganese source includes any one of manganese nitrate, manganese acetate or manganese chloride, or a combination of at least two of them.

[0038] Preferably, the zinc source includes any one of zinc nitrate, zinc acetate or zinc chloride, or a combination of at least two thereof.

[0039] Preferably, the concentration of the precipitant in step (2) is 0.3-3 mol / L, for example, 0.3 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L.

[0040] Preferably, the precipitant in step (2) comprises any one of a sodium source, an ammonia source or a potassium source, or a combination of at least two of them.

[0041] Preferably, the sodium source includes any one of sodium carbonate, sodium hydroxide or sodium bicarbonate, or a combination of at least two thereof.

[0042] Preferably, the ammonia source includes any one of ammonium carbonate, aqueous ammonia or ammonium bicarbonate, or a combination of at least two thereof.

[0043] Preferably, the potassium source includes any one of potassium carbonate, potassium hydroxide or potassium bicarbonate, or a combination of at least two of them.

[0044] Preferably, the specific process of the co-precipitation reaction in step (2) includes: adding the precursor solution and the precipitant into the bottom liquid in parallel.

[0045] Preferably, the base liquid comprises water.

[0046] Preferably, the pH value of the solution in the coprecipitation reaction in step (2) is 6-10, such as 6, 7, 8, 9 or 10.

[0047] In the present invention, the pH of the solution during the coprecipitation reaction is controlled within a specific range by adjusting the ratio of the precursor solution and the precipitant added in parallel to the base solution.

[0048] The present invention provides pH regulation of the coprecipitation reaction, which will affect the size and crystal form of crystal particles and can control the precipitation rate of metal ions, thereby obtaining a catalyst with excellent quality.

[0049] Preferably, the temperature of the coprecipitation reaction in step (2) is 20-80°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C.

[0050] Preferably, the coprecipitation reaction in step (2) is also accompanied by stirring.

[0051] Preferably, the stirring speed is 100-1000 r / min, for example, 100 r / min, 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min or 1000 r / min, etc.

[0052] Preferably, mixing is further performed after the coprecipitation reaction in step (2).

[0053] Preferably, the mixing method includes stirring.

[0054] Preferably, the mixing time is 0.5-2.5 h, such as 0.5 h, 1 h, 1.5 h, 2 h or 2.5 h.

[0055] Preferably, the mixing temperature is 20-80°C, such as 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C.

[0056] Preferably, the mixing rotation speed is 100-1000 r / min, for example, 100 r / min, 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min or 1000 r / min, etc.

[0057] Preferably, the mixing is followed by aging.

[0058] Preferably, the aging temperature is 20-80°C, such as 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C.

[0059] Preferably, the aging time is 0.5-12 h, for example, 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h or 12 h.

[0060] Preferably, after the separation in step (2), the separated precipitate is washed and dried in sequence.

[0061] Preferably, the washing solvent is deionized water.

[0062] Preferably, the washing temperature is 20-80°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C.

[0063] Preferably, the drying temperature is 100-180°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C.

[0064] Preferably, the drying time is 8-14 h, for example, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h or 14 h.

[0065] As a preferred technical method of the present invention, the preparation method comprises the following steps:

[0066] (1) mixing a samarium source, an M1 metal source, an M2 metal source and a solvent to obtain a precursor solution, wherein the total molar concentration of the metal elements in the precursor solution is 0.5-5 mol / L; based on the total molar amount of the metal elements in the precursor solution being 100 mol%, the molar percentage of the samarium element is 40-90 mol%, the molar percentage of the M1 metal element is 5-30 mol%, and the molar percentage of the M2 metal element is 5-30 mol%; the M1 metal source comprises any one of a cobalt source, a nickel source or a gallium source or a combination of at least two thereof; the M2 metal source comprises a manganese source and / or a zinc source;

[0067] (2) The precursor solution and a precipitant with a concentration of 0.3-3 mol / L are flowed into the bottom liquid for a co-precipitation reaction, the pH value of the solution in the co-precipitation reaction is controlled to be 6-10, and the temperature is 20-80°C. The co-precipitation reaction is also accompanied by stirring at a speed of 100-1000 r / min; then, the mixture is mixed at a speed of 100-1000 r / min at 20-80°C for 0.5-2.5 h, and then aged at 20-80°C for 0.5-12 h, and the precipitate is separated and washed with deionized water at a temperature of 20-80°C until the pH value is 7 and no cations in the precipitant are detected, and then dried at 100-180°C for 8-14 h to obtain the samarium-based catalyst.

[0068] In a third aspect, the present invention provides an application of the samarium-based catalyst according to the first aspect, wherein the samarium-based catalyst is applied to a normal-para hydrogen conversion reaction.

[0069] The samarium-based catalyst provided by the present invention can be used in the ortho-parahydrogen conversion reaction. Through the synergistic effect of the main component samarium element and the cobalt, nickel or gallium element in the first auxiliary agent and the manganese or zinc element in the second auxiliary agent, the process of the ortho-parahydrogen conversion reaction can be promoted, the conversion of orthohydrogen into parahydrogen can be promoted, and the conversion rate of the ortho-parahydrogen conversion reaction can be improved.

[0070] Preferably, the samarium-based catalyst is also subjected to activation treatment before use.

[0071] Preferably, the activation treatment comprises thermal activation.

[0072] Preferably, the temperature of the activation treatment is 100-150°C, such as 100°C, 110°C, 120°C, 130°C, 140°C or 150°C.

[0073] Preferably, the activation treatment is performed under a vacuum environment.

[0074] Preferably, the activation treatment time is 5-10 h, for example, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h.

[0075] Compared with the prior art, the present invention has at least the following beneficial effects:

[0076] (1) The samarium-based catalyst provided by the present invention has samarium oxide as the main component, cobalt, nickel or gallium oxide as the first auxiliary agent, and manganese or zinc oxide as the second auxiliary agent. The main component and the first and second auxiliary agents cooperate with each other to improve the catalytic performance and catalytic stability of the samarium-based catalyst, and has a higher conversion rate for catalyzing the normal-parahydrogen conversion reaction. The present invention uses samarium to replace the main component iron element in the conventional normal-parahydrogen conversion catalyst, which opens up a new idea and achieves a more excellent catalytic effect.

[0077] (2) The present invention mixes a samarium source with a cobalt source, a nickel source or a gallium source, and a manganese source and / or a zinc source as raw materials, and combines the mixture with a precipitant to carry out a co-precipitation reaction process, thereby obtaining a samarium-based catalyst with uniform distribution of active sites, stable structure, high mechanical strength, strong catalytic activity, and excellent catalytic performance and catalytic rate. The preparation process is simple, easy to operate, and has a low preparation cost, and is suitable for the industrial production of samarium-based catalysts.

[0078] (3) The samarium-based catalyst provided by the present invention can be used in the ortho-parahydrogen conversion reaction. Through the synergistic effect of the main component samarium element and the cobalt, nickel or gallium element in the first auxiliary agent and the manganese or zinc element in the second auxiliary agent, the process of the ortho-parahydrogen conversion reaction can be promoted, the conversion of orthohydrogen to parahydrogen can be promoted, and the conversion rate of the ortho-parahydrogen conversion reaction can be improved. DETAILED DESCRIPTION

[0079] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0080] Example 1

[0081] This embodiment provides a samarium-based catalyst, which has Sm2O3 as a main component, Co2O3 as a first auxiliary agent, and MnO2 as a second auxiliary agent. Taking the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar content of Sm element is 40 mol%, the molar content of Co element is 30 mol%, and the molar content of Mn element is 30 mol%.

[0082] This embodiment provides a method for preparing the above-mentioned samarium-based catalyst, which specifically comprises the following steps:

[0083] (1) Samarium nitrate, cobalt nitrate, manganese nitrate and deionized water are mixed to obtain a precursor solution; wherein the total molar concentration of the metal elements in the precursor solution is 1 mol / L, and the total molar amount of the metal elements in the precursor solution is 100 mol%, the molar percentage of the Sm element is 40 mol%, the molar percentage of the Co element is 30 mol%, and the molar percentage of the Mn element is 30 mol%.

[0084] (2) The precursor solution obtained in step (1) and sodium carbonate with a concentration of 1 mol / L are co-flowed into deionized water for a co-precipitation reaction, and the pH value of the solution is controlled to be 7 and the temperature is 70°C during the co-precipitation reaction. The co-precipitation reaction is also accompanied by stirring at a speed of 500 r / min; then, stirring is continued at a speed of 500 r / min at 70°C for 2 hours, and then, it is aged at 70°C for 4 hours, and then the precipitate is separated and washed with deionized water at a temperature of 70°C until the pH value is 7 and no cations in the precipitant sodium carbonate are detected, and then it is dried at 110°C for 10 hours to obtain a samarium-based catalyst.

[0085] Example 2

[0086] This embodiment provides a samarium-based catalyst, which has Sm2O3 as a main component, Co2O3 as a first auxiliary agent, and MnO2 as a second auxiliary agent. Taking the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar content of Sm element is 50 mol%, the molar content of Co element is 25 mol%, and the molar content of Mn element is 25 mol%.

[0087] This embodiment provides a method for preparing the above-mentioned samarium-based catalyst, which specifically comprises the following steps:

[0088] (1) Samarium nitrate, cobalt nitrate, manganese nitrate and deionized water are mixed to obtain a precursor solution; wherein the total molar concentration of the metal elements in the precursor solution is 2 mol / L, and the total molar amount of the metal elements in the precursor solution is 100 mol%, the molar percentage of the Sm element is 50 mol%, the molar percentage of the Co element is 25 mol%, and the molar percentage of the Mn element is 25 mol%.

[0089] (2) The precursor solution obtained in step (1) and sodium carbonate with a concentration of 3 mol / L are co-flowed into deionized water for co-precipitation reaction. The pH value of the solution is controlled to be 7 and the temperature is 70°C during the co-precipitation reaction. The co-precipitation reaction is accompanied by stirring at a speed of 500 r / min. Then, stirring is continued at a speed of 500 r / min at 70°C for 2 hours. Then, aging is carried out at 70°C for 4 hours. The precipitate is separated and washed with deionized water at a temperature of 70°C until the pH value is 7 and no cations in the precipitant sodium carbonate are detected. Then, it is dried at 100°C for 10 hours to obtain a samarium-based catalyst.

[0090] Example 3

[0091] This embodiment provides a samarium-based catalyst, which has Sm2O3 as a main component, Co2O3 as a first auxiliary agent, and MnO2 as a second auxiliary agent. Taking the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar content of Sm element is 65 mol%, the molar content of Co element is 30 mol%, and the molar content of Mn element is 5 mol%.

[0092] This embodiment provides a method for preparing the above-mentioned samarium-based catalyst, which specifically comprises the following steps:

[0093] (1) Samarium nitrate, cobalt acetate, manganese chloride and deionized water are mixed to obtain a precursor solution; wherein the total molar concentration of the metal elements in the precursor solution is 0.5 mol / L, and based on the total molar amount of the metal elements in the precursor solution being 100 mol%, the molar percentage of the Sm element is 65 mol%, the molar percentage of the Co element is 30 mol%, and the molar percentage of the Mn element is 5 mol%.

[0094] (2) The precursor solution obtained in step (1) and a precipitant composed of sodium carbonate, potassium carbonate and ammonium carbonate in a volume ratio of 1:1:1 are added to deionized water for coprecipitation reaction, wherein the concentration of sodium carbonate is 0.5 mol / L, the concentration of potassium carbonate is 0.5 mol / L, and the concentration of ammonium carbonate is 0.5 mol / L. The pH value of the solution during the coprecipitation reaction is controlled to be 6, and the temperature is 80°C. The coprecipitation reaction is also accompanied by stirring at a speed of 800 r / min, and then stirring is continued at a speed of 800 r / min at 80°C for 0.5 h. Then, aging is carried out at 80°C for 12 h, and then a precipitate is separated and washed with deionized water at a temperature of 80°C until the pH value is 7 and no cations in the precipitant are detected, and then dried at 180°C for 14 h to obtain a samarium-based catalyst.

[0095] Example 4

[0096] This embodiment provides a samarium-based catalyst, which has Sm2O3 as a main component, Co2O3 as a first auxiliary agent, and MnO2 as a second auxiliary agent. Taking the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar content of Sm element is 65 mol%, the molar content of Co element is 5 mol%, and the molar content of Mn element is 30 mol%.

[0097] This embodiment provides a method for preparing the above-mentioned samarium-based catalyst, which specifically comprises the following steps:

[0098] (1) Samarium acetate, cobalt chloride, manganese nitrate and deionized water are mixed to obtain a precursor solution; wherein the total molar concentration of the metal elements in the precursor solution is 5 mol / L, and the total molar amount of the metal elements in the precursor solution is 100 mol%, the molar percentage of the Sm element is 65 mol%, the molar percentage of the Co element is 5 mol%, and the molar percentage of the Mn element is 30 mol%.

[0099] (2) The precursor solution obtained in step (1) is mixed with a precipitant consisting of 1.5 mol / L sodium hydroxide and 1.5 mol / L sodium bicarbonate in a volume ratio of 1:1 and flowed into deionized water for co-precipitation reaction. The pH value of the solution is controlled to be 10 and the temperature is 20°C during the co-precipitation reaction. The co-precipitation reaction is also accompanied by stirring at a speed of 200 r / min. Then, stirring is continued at a speed of 200 r / min at 20°C for 2.5 hours. Then, aging is carried out at 20°C for 0.5 hours. The precipitate is separated and washed with deionized water at a temperature of 20°C until the pH value is 7 and no cations in the precipitant are detected. The precipitate is dried at 100°C for 8 hours to obtain a samarium-based catalyst.

[0100] Example 5

[0101] The present embodiment provides a samarium-based catalyst, which has Sm2O3 as a main component, Co2O3 as a first auxiliary agent, and MnO2 as a second auxiliary agent. Taking the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar content of Sm element is 70 mol%, the molar content of Co element is 15 mol%, and the molar content of Mn element is 15 mol%.

[0102] This embodiment provides a method for preparing the above-mentioned samarium-based catalyst, which specifically comprises the following steps:

[0103] (1) Samarium chloride, cobalt chloride, manganese acetate and deionized water are mixed to obtain a precursor solution; wherein the total molar concentration of the metal elements in the precursor solution is 2 mol / L, and based on the total molar amount of the metal elements in the precursor solution being 100 mol%, the molar percentage of the Sm element is 70 mol%, the molar percentage of the Co element is 15 mol%, and the molar percentage of the Mn element is 15 mol%.

[0104] (2) The precursor solution obtained in step (1) is mixed with a precipitant consisting of 1 mol / L ammonia water, 1 mol / L potassium hydroxide and 1 mol / L sodium bicarbonate in a volume ratio of 1:1:1 and flowed into deionized water for co-precipitation reaction, wherein the pH value of the solution is controlled to be 9 and the temperature is controlled to be 80°C during the co-precipitation reaction. The co-precipitation reaction is also accompanied by stirring at a speed of 1000 r / min, and then stirring is continued at a speed of 1000 r / min at 80°C for 0.5 h. Subsequently, the mixture is aged at 80°C for 12 h, and then a precipitate is separated and washed with deionized water at a temperature of 80°C until the pH value is 7 and no cations in the precipitant are detected, and then dried at 120°C for 8 h to obtain a samarium-based catalyst.

[0105] Example 6

[0106] This embodiment provides a samarium-based catalyst, which has Sm2O3 as a main component, Co2O3 as a first auxiliary agent, and MnO2 as a second auxiliary agent. Taking the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar content of Sm element is 80 mol%, the molar content of Co element is 10 mol%, and the molar content of Mn element is 10 mol%.

[0107] This embodiment provides a method for preparing the above-mentioned samarium-based catalyst, which specifically comprises the following steps:

[0108] (1) Samarium acetate, cobalt nitrate, manganese chloride and deionized water are mixed to obtain a precursor solution; wherein the total molar concentration of the metal elements in the precursor solution is 4 mol / L, and based on the total molar amount of the metal elements in the precursor solution being 100 mol%, the molar percentage of the Sm element is 80 mol%, the molar percentage of the Co element is 10 mol%, and the molar percentage of the Mn element is 10 mol%.

[0109] (2) The precursor solution obtained in step (1) and a precipitant consisting of 1 mol / L ammonia water, 1 mol / L potassium carbonate and 1 mol / L potassium bicarbonate in a volume ratio of 1:1:1 are added to deionized water for co-precipitation reaction, the pH value of the solution is controlled to be 10 and the temperature is 80°C during the co-precipitation reaction, and the co-precipitation reaction is accompanied by stirring at a speed of 700 r / min, and then stirring is continued at a speed of 700 r / min at 80°C for 2.5 hours, then aging at 80°C for 12 hours, and then separating and taking a precipitate, washing the obtained precipitate with deionized water at a temperature of 80°C until the pH value is 7 and no cations in the precipitant are detected, and then drying at 120°C for 10 hours to obtain a samarium-based catalyst.

[0110] Example 7

[0111] This embodiment provides a samarium-based catalyst, which has Sm2O3 as a main component, Co2O3 as a first auxiliary agent, and MnO2 as a second auxiliary agent. Taking the total molar amount of metal elements in the samarium-based catalyst as 100 mol%, the molar content of Sm element is 90 mol%, the molar content of Co element is 5 mol%, and the molar content of Mn element is 5 mol%.

[0112] This embodiment provides a method for preparing the above-mentioned samarium-based catalyst, which specifically comprises the following steps:

[0113] (1) Cobalt nitrate, cobalt nitrate, cobalt nitrate and deionized water are mixed to obtain a precursor solution; wherein the total molar concentration of the metal elements in the precursor solution is 2 mol / L, and the total molar amount of the metal elements in the precursor solution is 100 mol%, the molar percentage of the Sm element is 90 mol%, the molar percentage of the Co element is 5 mol%, and the molar percentage of the Mn element is 5 mol%.

[0114] (2) The precursor solution obtained in step (1) and a precipitant consisting of 1 mol / L ammonia water, 1 mol / L potassium hydroxide and 1 mol / L ammonium bicarbonate in a volume ratio of 1:1:1 are flowed into deionized water for co-precipitation reaction, the pH value of the solution is controlled to be 8 and the temperature is 80°C during the co-precipitation reaction, and the co-precipitation reaction is accompanied by stirring at a speed of 600 r / min, and then the stirring is continued at a speed of 600 r / min at 80°C for 2.5 hours, and then the mixture is aged at 80°C for 10 hours, and then the precipitate is separated and washed with deionized water at a temperature of 80°C until the pH value is 7 and no cations in the precipitant are detected, and then dried at 180°C for 14 hours to obtain a samarium-based catalyst.

[0115] Example 8

[0116] The difference between this embodiment and embodiment 1 is that the samarium-based catalyst provided in this embodiment replaces the first auxiliary agent Co2O3 with NiO; accordingly, the cobalt nitrate in the preparation method of the samarium-based catalyst provided is replaced with nickel nitrate. The rest of the contents are the same as those in embodiment 1.

[0117] Example 9

[0118] The difference between this embodiment and embodiment 1 is that the samarium-based catalyst provided in this embodiment replaces the first auxiliary agent Co2O3 with Ga2O3; accordingly, the cobalt nitrate in the preparation method of the samarium-based catalyst provided is replaced with gallium nitrate. The rest of the contents are the same as those in embodiment 1.

[0119] Example 10

[0120] The difference between this embodiment and embodiment 1 is that the second auxiliary agent MnO2 in the samarium-based catalyst provided in this embodiment is replaced by ZnO; accordingly, the manganese nitrate in the preparation method of the samarium-based catalyst provided is replaced by zinc nitrate. The rest of the contents are the same as those in embodiment 1.

[0121] Embodiment 11

[0122] The difference between this embodiment and embodiment 1 is that this embodiment provides a samarium-based catalyst, in which the molar content of the Sm element is 35 mol%, the molar content of the Co element is 35 mol%, and the molar content of the Mn element is 30 mol%, based on the total molar amount of the metal elements in the samarium-based catalyst being 100 mol%. The rest of the contents are the same as those in embodiment 1.

[0123] Example 12

[0124] The difference between this embodiment and embodiment 1 is that this embodiment provides a samarium-based catalyst, in which the molar content of the Sm element is 95 mol%, the molar content of the Co element is 2 mol%, and the molar content of the Mn element is 3 mol%, based on the total molar amount of the metal elements in the samarium-based catalyst being 100 mol%. The rest of the contents are the same as those in embodiment 1.

[0125] Embodiment 13

[0126] The difference between this embodiment and embodiment 1 is that this embodiment provides a samarium-based catalyst, in which the molar content of the Sm element is 69 mol%, the molar content of the Co element is 1 mol%, and the molar content of the Mn element is 30 mol%, based on the total molar amount of the metal elements in the samarium-based catalyst being 100 mol%. The rest of the contents are the same as those in embodiment 1.

[0127] Embodiment 14

[0128] The difference between this embodiment and embodiment 1 is that this embodiment provides a samarium-based catalyst, in which the molar content of the Sm element is 40 mol%, the molar content of the Co element is 45 mol%, and the molar content of the Mn element is 15 mol%, based on the total molar amount of the metal elements in the samarium-based catalyst being 100 mol%. The rest of the contents are the same as those in embodiment 1.

[0129] Embodiment 15

[0130] The difference between this embodiment and embodiment 1 is that this embodiment provides a samarium-based catalyst, in which the molar content of the Sm element is 69 mol%, the molar content of the Co element is 30 mol%, and the molar content of the Mn element is 1 mol%, based on the total molar amount of the metal elements in the samarium-based catalyst being 100 mol%. The rest of the contents are the same as those in embodiment 1.

[0131] Example 16

[0132] The difference between this embodiment and embodiment 1 is that this embodiment provides a samarium-based catalyst, in which the molar content of the Sm element is 40 mol%, the molar content of the Co element is 15 mol%, and the molar content of the Mn element is 45 mol%, based on the total molar amount of the metal elements in the samarium-based catalyst being 100 mol%. The rest of the contents are the same as those in embodiment 1.

[0133] Embodiment 17

[0134] The difference between this embodiment and embodiment 1 is that in the preparation method of the samarium-based catalyst provided in this embodiment, the pH value of the solution in the coprecipitation reaction is 5. The rest of the contents are the same as those in embodiment 1.

[0135] Embodiment 18

[0136] The difference between this embodiment and embodiment 1 is that in the preparation method of the samarium-based catalyst provided in this embodiment, the pH value of the solution in the coprecipitation reaction is 11. The rest of the contents are the same as those in embodiment 1.

[0137] Comparative Example 1

[0138] The difference between this comparative example and Example 2 is that the first auxiliary agent Co2O3 and the second auxiliary agent MnO2 are omitted in the samarium-based catalyst provided in this comparative example, and only the main component Sm2O3 is used as a catalyst; accordingly, in the preparation method of the samarium-based catalyst, samarium nitrate is used as a raw material and mixed with deionized water to obtain a precursor solution. The rest of the contents are the same as Example 2.

[0139] Comparative Example 2

[0140] The difference between this comparative example and Example 2 is that the second auxiliary agent MnO2 is omitted in the samarium-based catalyst provided in this comparative example, and the catalyst includes a main component Sm2O3 and a first auxiliary agent Co2O3. The molar content of the Sm element is 50mol%, and the molar content of the Co element is 50mol%, based on the total molar amount of the metal elements in the samarium-based catalyst being 100mol%. Correspondingly, in the preparation method of the samarium-based catalyst, samarium nitrate and cobalt nitrate are mixed as raw materials with deionized water to obtain a precursor solution. The molar percentage of the Sm element is 50mol%, and the molar percentage of the Co element is 50mol%, based on the total molar amount of the metal elements in the precursor solution being 100mol%. The rest of the contents are the same as in Example 2.

[0141] Comparative Example 3

[0142] The difference between this comparative example and Example 2 is that the first auxiliary agent Co2O3 is omitted in the samarium-based catalyst provided in this comparative example, and the catalyst includes the main component Sm2O3 and the second auxiliary agent MnO2. The molar content of the Sm element is 50mol% and the molar content of the Mn element is 50mol%, based on the total molar amount of the metal elements in the samarium-based catalyst being 100mol%. Correspondingly, in the preparation method of the samarium-based catalyst, samarium nitrate and manganese nitrate are mixed as raw materials with deionized water to obtain a precursor solution. The molar percentage of the Sm element is 50mol% and the molar percentage of the Mn element is 50mol%, based on the total molar amount of the metal elements in the precursor solution being 100mol%. The rest of the contents are the same as in Example 2.

[0143] Comparative Example 4

[0144] The difference between this comparative example and Example 2 is that the main component Sm2O3 is omitted in the catalyst provided in this comparative example, and the catalyst only includes the first auxiliary agent Co2O3 and the second auxiliary agent MnO2. The total molar amount of the metal elements in the catalyst is 100 mol%, and the molar content of the Co element is 50 mol%, and the molar content of the Mn element is 50 mol%. Correspondingly, in the preparation method of the catalyst, cobalt nitrate and manganese nitrate are mixed with deionized water as raw materials to obtain a precursor solution. The total molar amount of the metal elements in the precursor solution is 100 mol%, and the molar percentage of the Co element is 50 mol%, and the molar percentage of the Mn element is 50 mol%. The rest of the content is the same as Example 2.

[0145] The catalyst activity of the catalysts provided in Examples 1-18 and Comparative Examples 1-4 was tested. The specific test process included: placing the catalysts provided in Examples 1-18 and Comparative Examples 1-4 (mass = 1 g) in a copper tube with an inner diameter of 10 mm for vacuum heating activation, the vacuum degree was -99 kPa, the addition temperature was 130° C., and the activation was performed for 6 hours. After activation, the copper tube containing the activated catalyst was quickly transferred to a liquid nitrogen (77K) low-temperature bath, 90 ml / min of dry hydrogen was introduced into the inlet of the copper tube, and the volume content of parahydrogen (the volume fraction of parahydrogen in the total hydrogen, recorded as C) was recorded every 4 minutes at the outlet of the copper tube using a gas chromatograph (Fulley GC9790). pH2 ), calculate the conversion rate of normal and secondary hydrogen (denoted as X OPC ), take the data points within 1 hour after the start of the test as the average value, and record it as the initial activity of the catalyst (X OPC-0 and C pH2-0 Then, a hydrogen-water mixture with a water content of 100 ppm was introduced, and the catalyst activity data (X OPC and C pH2 ), until the conversion rate drops to the initial activity X OPC-0The experiment is terminated when the reaction time reaches 80%, and the reaction time is recorded as the catalyst stabilization time. The longer the stabilization time, the higher the catalyst stability. The test results of the catalysts prepared in different embodiments and comparative examples are shown in Table 1.

[0146] Table 1

[0147]

[0148] The test results show that:

[0149] (1) It can be seen from Examples 1 to 10 that the samarium-based catalyst provided by the present invention has samarium oxide as the main component, cobalt, nickel or gallium oxide as the first auxiliary agent, and manganese or zinc oxide as the second auxiliary agent. The main component and the first and second auxiliary agents work together to improve the catalytic performance and catalytic stability of the samarium-based catalyst, and has a higher conversion rate for catalyzing the normal-parahydrogen conversion reaction.

[0150] (2) By comparing Example 1 with Examples 11-16, it can be seen that if the content of samarium is too low, it is insufficient to provide sufficient active sites, which affects the conversion efficiency of orthohydrogen to parahydrogen, resulting in a decrease in catalytic performance, a low content of parahydrogen obtained after catalysis, and a decrease in conversion rate; if the content of samarium is too high, too much samarium oxide will be formed in the catalyst, resulting in the formation of SmO on the catalyst surface. x The thin layer covers the active sites, reducing the effective adsorption of orthohydrogen and parahydrogen, thereby reducing the activity of the catalyst. The parahydrogen content obtained after catalysis is low, and the conversion rate is reduced. If the content of the metal element in the first auxiliary agent is too low, the electronic spin and catalytic activity of the catalyst will decrease. The low content of cobalt, nickel or gallium metal elements is not enough to form an efficient bimetallic oxide structure with samarium oxide, which affects the rate of the catalyst's conversion of orthohydrogen and parahydrogen, resulting in a decrease in the conversion rate of the reaction and the volume content of parahydrogen. If the content of the metal M1 element in the first auxiliary agent is too high, it will compete with the samarium element for active sites, affecting the adsorption and activation ability of the samarium element, thereby reducing the overall performance of the catalyst. If the content of the metal M2 element in the second auxiliary agent is too low, the proportion of the structural auxiliary agent manganese or zinc metal element will be reduced, and the selective adsorption of water and the good dispersion of the active components cannot be achieved, thereby reducing the stability and catalytic effect of the catalyst, resulting in a decrease in the reaction conversion rate and the resulting parahydrogen content, and a shortened stabilization time; if the content of the metal element in the second auxiliary agent is too high, it will change the redox properties of the catalyst and affect its ability to activate orthohydrogen molecules.

[0151] (3) By comparing Example 1 with Examples 17-18, it can be seen that in the preparation method of the samarium-based catalyst provided by the present invention, if the pH of the coprecipitation reaction is adjusted too low, it will lead to incomplete precipitation of metal ions and hindered crystal growth, thereby affecting the quality and performance of the obtained catalyst, and further resulting in a decrease in the conversion rate of the catalytic parahydrogen reaction and the obtained parahydrogen content; if the pH of the coprecipitation reaction is adjusted too high, it will lead to too fast precipitation, and the formed particles will be larger, affecting the specific surface area of ​​the catalyst and promoting the phase change or agglomeration of the metal oxide, so that the active component is wrapped, thereby causing the catalytic performance of the catalyst to decrease, affecting the conversion rate of the parahydrogen reaction and the obtained parahydrogen content.

[0152] (4) By comparing Example 2 with Comparative Example 1, it can be seen that if only samarium oxide is used as the catalyst in the present invention, the catalytic performance of the catalyst will deteriorate. In the catalytic process of the ortho-parahydrogen conversion reaction, the conversion rate of orthohydrogen to parahydrogen will decrease, the parahydrogen content will decrease, and the catalytic stability will deteriorate.

[0153] (5) By comparing Example 2 with Comparative Examples 2-4, it can be seen that if any component is missing from the catalyst provided by the present invention, the catalytic performance of the catalyst will be deteriorated. In the catalytic process of the ortho-parahydrogen conversion reaction, the conversion rate of orthohydrogen to parahydrogen will decrease, the parahydrogen content will decrease, and the catalytic stability will deteriorate. In particular, the lack of the main component samarium will lead to a significant decrease in catalytic performance.

[0154] In summary, the samarium-based catalyst provided by the present invention uses samarium oxide as the main component, uses cobalt, nickel or gallium oxide as the first auxiliary agent, and manganese or zinc oxide as the second auxiliary agent. The main component and the first and second auxiliary agents cooperate with each other, which can improve the catalytic performance and catalytic stability of the samarium-based catalyst, and has a higher conversion rate for catalyzing the normal-parahydrogen conversion reaction. The present invention uses samarium element to replace the main component iron element in the conventional normal-parahydrogen conversion catalyst, which opens up a new idea and achieves a more excellent catalytic effect.

[0155] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A samarium-based catalyst for normal-parahydrogen conversion, characterized in that: The samarium-based catalyst comprises a main component and an auxiliary agent, wherein the main component comprises samarium oxide, and the auxiliary agent comprises a first auxiliary agent and a second auxiliary agent; The first additive includes an oxide containing a metal M1; the metal M1 includes any one of cobalt, nickel or gallium or a combination of at least two thereof; The second auxiliary agent includes an oxide containing a metal M2; the metal M2 includes manganese and / or zinc.

2. The samarium-based catalyst according to claim 1, characterized in that Based on the total molar amount of metal elements in the samarium-based catalyst being 100 mol%, the molar percentage content of the samarium element is 40-90 mol%; Preferably, based on the total molar amount of metal elements in the samarium-based catalyst being 100 mol%, the molar percentage of the metal M1 is 5-30 mol%; Preferably, based on the total molar amount of metal elements in the samarium-based catalyst being 100 mol%, the molar percentage of the metal M2 is 5-30 mol%.

3. A method for preparing a samarium-based catalyst according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: (1) mixing a samarium source, an M1 metal source, an M2 metal source and a solvent to obtain a precursor solution; The M1 metal source includes any one of a cobalt source, a nickel source or a gallium source, or a combination of at least two thereof; The M2 metal source includes a manganese source and / or a zinc source; (2) subjecting the precursor solution and the precipitant to a coprecipitation reaction, and separating them to obtain the samarium-based catalyst.

4. The preparation method according to claim 3, characterized in that: Taking the total molar amount of the metal elements in the precursor solution of step (1) as 100 mol%, the molar percentage content of the samarium element is 40-90 mol%; Preferably, based on the total molar amount of the metal elements in the precursor solution in step (1) being 100 mol%, the molar percentage content of the M1 metal element is 5-30 mol%; Preferably, based on the total molar amount of metal elements in the precursor solution in step (1) being 100 mol%, the molar percentage content of the M2 metal element is 5-30 mol%.

5. The preparation method according to claim 3 or 4, characterized in that: The total molar concentration of the metal elements in the precursor solution of step (1) is 0.5-5 mol / L; Preferably, the concentration of the precipitant in step (2) is 0.3-3 mol / L; Preferably, the precipitant in step (2) comprises any one of a sodium source, an ammonia source or a potassium source, or a combination of at least two of them.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The specific process of the coprecipitation reaction in step (2) includes: adding the precursor solution and the precipitant into the bottom liquid in parallel; Preferably, the base liquid comprises water; Preferably, the pH value of the solution in the coprecipitation reaction in step (2) is 6-10; Preferably, the temperature of the coprecipitation reaction in step (2) is 20-80°C; Preferably, the coprecipitation reaction in step (2) is also accompanied by stirring; Preferably, the stirring speed is 100-1000 r / min.

7. The preparation method according to any one of claims 3 to 6, characterized in that: The coprecipitation reaction in step (2) is followed by mixing; Preferably, the mixing time is 0.5-2.5h; Preferably, the mixing speed is 100-1000r / min; Preferably, the mixing is followed by aging; Preferably, the aging temperature is 20-80°C; Preferably, the aging time is 0.5-12h.

8. The preparation method according to any one of claims 3 to 7, characterized in that: After the separation in step (2), the separated precipitate is washed and dried in sequence; Preferably, the washing solvent is deionized water; Preferably, the washing temperature is 20-80°C; Preferably, the drying temperature is 100-180°C; Preferably, the drying time is 8-14 hours.

9. The preparation method according to claim 3, characterized in that: The preparation method comprises the following steps: (1) mixing a samarium source, an M1 metal source, an M2 metal source and a solvent to obtain a precursor solution, wherein the total molar concentration of the metal elements in the precursor solution is 0.5-5 mol / L; based on the total molar amount of the metal elements in the precursor solution being 100 mol%, the molar percentage of the samarium element is 40-90 mol%, the molar percentage of the M1 metal element is 5-30 mol%, and the molar percentage of the M2 metal element is 5-30 mol%; the M1 metal source comprises any one of a cobalt source, a nickel source or a gallium source or a combination of at least two thereof; the M2 metal source comprises a manganese source and / or a zinc source; (2) The precursor solution and a precipitant with a concentration of 0.3-3 mol / L are flowed into the bottom liquid for a co-precipitation reaction, the pH value of the solution in the co-precipitation reaction is controlled to be 6-10, and the temperature is 20-80°C. The co-precipitation reaction is also accompanied by stirring at a speed of 100-1000 r / min; then, the mixture is mixed at a speed of 100-1000 r / min at 20-80°C for 0.5-2.5 h, and then aged at 20-80°C for 0.5-12 h, and the precipitate is separated and washed with deionized water at a temperature of 20-80°C until the pH value is 7 and no cations in the precipitant are detected, and then dried at 100-180°C for 8-14 h to obtain the samarium-based catalyst.

10. Use of the samarium-based catalyst according to claim 1 or 2, characterized in that: The samarium-based catalyst is used in the ortho-parahydrogen conversion reaction.

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