Preparation method and application of manganese oxide-based ortho-parahydrogen conversion catalyst

Abstract

The invention relates to a preparation method and application of a manganese oxide-based ortho-parahydrogen conversion catalyst, and the preparation method comprises the following steps: mixing a manganese source, a reaction auxiliary agent and a carrier in a reaction solvent, and then carrying out solvent heat treatment to obtain the manganese oxide-based ortho-parahydrogen conversion catalyst. Compared with the prior art, the active component manganese oxide in the prepared catalyst is tightly combined with the carrier, the performance is excellent, and the durability is good; meanwhile, the preparation method is simple, strict conditions and high-temperature calcination treatment are not needed, catalysts with different macroscopic particle sizes can be obtained according to actual requirements, and the method has a good industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen liquefaction and relates to a preparation method and application of a manganese oxide-based ortho-parahydrogen conversion catalyst. Background Art

[0002] As a zero-carbon energy, hydrogen is one of the important ways for my country to achieve its "dual carbon" goals. The density of liquid hydrogen is 70.8kg / m 3 , which is 850 times that of ordinary hydrogen. This makes liquid hydrogen have an ultra-high energy density per unit volume. Therefore, the production, storage and transportation of liquid hydrogen are the key to the large-scale application of hydrogen energy.

[0003] In addition to multiple isotopes, hydrogen molecules can also be divided into two isomers, orthohydrogen and parahydrogen, according to the difference in the spin states of the two atomic nuclei in the hydrogen molecule. The ratio of the two in hydrogen is a function of temperature. At room temperature, the ratio of orthohydrogen to parahydrogen in hydrogen is about 3:1, and this ratio is close to 1:1 at liquid nitrogen temperature. At liquid hydrogen temperature, almost all hydrogen molecules exist in the form of parahydrogen. When hydrogen is liquefied, as the temperature decreases, the molecular energy also continues to decrease, and the hydrogen molecules will gradually transform from the high-energy orthohydrogen state to the low-energy parahydrogen state. This conversion speed is slow and constantly releases heat. Near the liquid hydrogen temperature zone, the heat release value is 706kJ / kg, which is much larger than the latent heat of vaporization of liquid hydrogen (447kJ / kg), which will lead to a large amount of evaporation loss of liquid hydrogen. Therefore, unlike the liquefaction process of other gases, in addition to cooling and pressurizing operations, the hydrogen liquefaction process must also use an ortho-parahydrogen conversion catalyst to quickly adjust the ortho-parahydrogen ratio in hydrogen to a balanced state.

[0004] The most widely used catalyst for hydrogen conversion in liquid hydrogen plants is the catalyst from the American company The iron oxide catalyst has the advantages of high activity, good stability and long service life. However, the particle size of this iron oxide catalyst is fixed and cannot be customized. It is easy to pulverize under the scouring of airflow, causing the flow resistance of the catalyst bed to increase, increasing the overall pressure drop of the liquefaction equipment, and the catalyst preparation process requires crushing and granulation, so the yield is low. In order to solve the above problems, it is still very urgent to design and synthesize catalysts with low flow resistance, controllable particle size and excellent activity.

[0005] Chinese patent CN115155583A discloses an electrically supported para-hydrogen conversion catalyst and a preparation method thereof. In particular, it relates to using activated carbon as a load, using an electrodeposition method to electroplate a metal inside the activated carbon, and then converting the metal into a metal oxide to obtain an electrically supported para-hydrogen conversion catalyst. The electrodeposition method can make the metal oxide more evenly distributed inside the activated carbon, so that the metal oxide and the load are more firmly combined; the addition of ultrafine sodium chloride powder can make the catalyst have adjustable pores and reduce the flow resistance of the catalyst. Although the electrodeposition method adopted in this invention can make the metal oxide active components more evenly distributed inside the activated carbon, the preparation process is relatively cumbersome, and the obtained catalyst is in powder form, and needs to be secondary granulated by an anhydrous binder before it can be used for para-hydrogen conversion catalysis, which is not conducive to the practical application of the catalyst.

[0006] Chinese patent CN112044457B discloses a supported para-hydrogen conversion catalyst and its preparation method. It particularly relates to using non-metallic ion modified materials as a load, using equal volume of metal nitrate impregnation and then calcination to obtain a supported para-hydrogen conversion catalyst. On the one hand, porous materials as loads can provide support for metal oxide components and reduce the flow resistance of the catalyst bed; on the other hand, the use of non-metallic ion modification can adjust the acidity of the material surface, which helps the metal oxide to adhere more evenly and improve the overall activity. The method used in this invention requires multi-step solution treatment and multi-step high-temperature calcination of the carrier, and the preparation of multiple solutions. The process is relatively cumbersome, and hazardous chemicals such as phosphoric acid, ammonium fluoride, and hydrofluoric acid are required in the prepared non-metallic ion precursor, which is not conducive to large-scale safe synthesis.

[0007] Chinese patent CN115920919A discloses a catalyst for ortho-parahydrogen conversion suitable for a wide range of low temperature conditions and its preparation method. In particular, it relates to a fiber magnetic catalyst FeMnO2 with orderly doping of Fe atoms obtained by mixing and post-calcination using α-MnO2 as a substrate and iron salt as a precursor. x . The coordination of lattice oxygen in α-MnO2 and Fe atoms can effectively avoid changes in the valence state of Fe atoms, which helps the catalyst maintain good stability under a wide range of low temperature conditions from 23K to 77K. The valence states of Mn and Fe elements in the catalyst prepared by the method adopted in this invention are +4 and 0, respectively, and the number of unpaired electrons outside the nucleus is small, which cannot provide sufficient magnetic moment and flipping force for the conversion of ortho-parahydrogen. In addition, a very high post-calcination temperature is required during the preparation process, and the catalyst is obtained in powder form, which is not conducive to filling in the converter. Summary of the invention

[0008] The purpose of the present invention is to provide a preparation method and application of a manganese oxide-based ortho-parahydrogen conversion catalyst, which is suitable for carriers with a wide range of particle sizes, and the manganese oxide is uniformly grown on the surface of the carrier through solvent thermal treatment. The preparation process is simple, the active components are evenly distributed, carriers with different particle sizes can be used according to actual needs, the catalytic activity is high, and no secondary granulation process is required.

[0009] The purpose of the present invention can be achieved by the following technical solutions:

[0010] The first aspect of the present invention provides a method for preparing a manganese oxide-based ortho-parahydrogen conversion catalyst, comprising:

[0011] A manganese source, a reaction aid and a carrier are mixed in a reaction solvent, and then subjected to solvent thermal treatment to obtain a manganese oxide-based ortho-parahydrogen conversion catalyst.

[0012] Furthermore, the manganese source is selected from at least one of manganese acetate, potassium permanganate, manganese sulfate or manganese nitrate.

[0013] Furthermore, the concentration of the manganese element in the manganese source in the reaction solvent is 0.01 to 1 mol / L.

[0014] Furthermore, the reaction aid is selected from at least one of glucose, oleic acid or cetyltrimethylammonium bromide (CTAB); the molar ratio of the reaction aid to the manganese element in the manganese source is (1-10):1.

[0015] Furthermore, the carrier is selected from at least one of alumina, molecular sieve, activated carbon or silicon dioxide, and the particle size of the carrier is 0.1 to 5 mm.

[0016] Furthermore, the mass ratio of the carrier to the manganese element in the manganese source is (5-20):1.

[0017] Furthermore, the reaction solvent is selected from at least one of water, ethanol or ethylene glycol.

[0018] Furthermore, the reaction solvent is a mixture of ethanol or ethylene glycol and water in a volume ratio of 5:(1-3).

[0019] Furthermore, in the solvent thermal treatment, the treatment temperature is 100 to 200° C. and the treatment time is 3 to 18 hours.

[0020] The second aspect of the present invention provides an application of a manganese oxide-based para-hydrogen conversion catalyst, comprising using the manganese oxide-based para-hydrogen conversion catalyst for a para-hydrogen conversion reaction.

[0021] Furthermore, before the ortho-parahydrogen conversion catalytic reaction, the catalyst is activated in a vacuum environment at 100-140° C. for 10-14 hours.

[0022] Furthermore, in the catalytic reaction of the ortho-parahydrogen conversion, the reaction temperature is 70-80K and the space velocity is 10000-60000h -1 The reaction time is 24 to 480 hours.

[0023] Compared with the prior art, the present invention has the following characteristics:

[0024] 1) In the method adopted by the present invention, except for some manganese sources, the chemical reagents used are simple, cheap, non-toxic and harmless, the reaction conditions are mild and controllable, and high-temperature calcination and secondary granulation are not required, which is suitable for batch preparation of the required catalyst.

[0025] 2) The solvent thermal method used in the present invention is an in-situ preparation method. The catalytically active component manganese oxide is generated in-situ on the surface of the carrier. Compared with the general physical grinding mixing or impregnation method, the active component and the carrier are more tightly combined, and the high activity can still be stably maintained under the flushing of hydrogen flow for a long time.

[0026] 3) The solvent thermal method adopted in the present invention is applicable to carriers with a wide range of particle sizes, and in the obtained catalyst, the active component manganese oxide is evenly distributed on the surface of the carrier, maintaining the high mechanical strength and particle size of the carrier, and can effectively reduce the catalyst bed resistance.

[0027] 4) The method adopted by the present invention can control the conditions such as reaction aids, reaction temperature and reaction time to obtain manganese oxide with different valence states, and the valence state of manganese element is relatively low (+2, +3). Compared with manganese element with a valence of +4, it has more unpaired electrons outside the nucleus and has better catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A graph showing the conversion rate of para-hydrogen of a manganese oxide-based para-hydrogen conversion catalyst prepared in the examples and comparative examples under different hydrogen space velocity conditions;

[0029] Figure 2 The XRD spectrum of a manganese oxide-based para-hydrogen conversion catalyst prepared in the examples and comparative examples;

[0030] Figure 3 The XPS spectrum of Mn2p of the Mn element in a manganese oxide-based para-hydrogen conversion catalyst prepared in Examples 1 to 3;

[0031] Figure 4 SEM images (a-c) of 4A molecular sieve, SEM images (d-i) and EDS-mapping images (g-i) of the Mn3O4 / 4A catalyst prepared in Example 2. DETAILED DESCRIPTION

[0032] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0033] A catalyst that can be used for normal-parahydrogen conversion reaction, and a preparation method thereof comprises:

[0034] The manganese source and the reaction aid are added to the solvent, stirred for 5 to 10 minutes to completely dissolve, and the carrier is added, and the stirring is continued for 30 to 60 minutes until a large amount of manganese ions are adsorbed on the surface of the carrier, and then the mixed solution is transferred to a closed high-pressure reactor, and then the high-pressure reactor is placed in an oven. Under heating conditions, a certain pressure is generated in the reactor, and the manganese ions are gradually converted into manganese oxide on the surface of the carrier. After the heating is completed, it is naturally cooled to room temperature, washed and dried to obtain a manganese oxide-based ortho-parahydrogen conversion catalyst.

[0035] Among them, the manganese source is one or more of manganese acetate, potassium permanganate, manganese sulfate, and manganese nitrate; the concentration of the manganese source is 0.01-1 mol / L; the solvent is preferably one or more of water, ethanol, and ethylene glycol; the reaction aid is preferably one or more of glucose, oleic acid, and CTAB; the molar ratio of the reaction aid to the manganese source is (1-10):1; the carrier is preferably one or more of alumina, molecular sieves, activated carbon, and silicon dioxide, and the particle size is 0.05-5 mm; the mass ratio of the carrier to the manganese element in the manganese source is preferably (5-20):1; the heating temperature is preferably 100-200°C, and the time is preferably 3-18h; the drying temperature is preferably 60-100°C, and the time is preferably 8-24h.

[0036] The catalyst prepared by the present invention is a manganese oxide-based supported catalyst prepared by a solvent thermal method, which has the characteristics of a simple preparation method and mild and controllable preparation conditions, and does not require harsh conditions and high-temperature calcination treatment. Catalysts with different macroscopic particle sizes can be obtained according to actual needs. At the same time, the active components are tightly combined with the carrier, and the catalyst has the advantages of excellent performance, good durability, high mechanical strength, and a large specific surface area. It is suitable for large-scale preparation and production and has good industrial application prospects.

[0037] The following are more detailed implementation cases, which further illustrate the technical solutions of the present invention and the technical effects that can be obtained.

[0038] In the following examples, unless otherwise specified, raw materials, reagents or processing techniques are all conventional commercial products or conventional processing techniques in the art.

[0039] Example 1

[0040] A manganese-based catalyst, the preparation method of which comprises:

[0041] Weigh 0.3675g of manganese acetate tetrahydrate (0.0015mol) and 2.119g of oleic acid (0.0075mol), add 50mL of ethanol and 20mL of water, stir for 5min to completely dissolve it, add 0.825g of alumina with an average particle size of 0.1mm, continue stirring for 30min, transfer the mixed solution to a 100mL polytetrafluoroethylene-lined reactor, seal the reactor and place it in a blast electric oven, set the temperature to 120℃, start timing when the oven temperature rises to 120℃, end heating after 5h, take out the reactor and cool it naturally to room temperature, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 60℃ for 12h to obtain the catalyst, recorded as MnO / Al2O3.

[0042] Example 2

[0043] A manganese-based catalyst, the preparation method of which comprises:

[0044] Weigh 0.395g potassium permanganate (0.0025mol) and 0.45g glucose (0.0025mol), add 65mL water, stir for 10min to completely dissolve, add 1.375g 4A molecular sieve with an average particle size of 1mm, continue stirring for 30min, transfer the mixed solution to a 100mL polytetrafluoroethylene-lined reactor, seal the reactor and place it in a blast electric oven, set the temperature to 150℃, start timing when the oven temperature rises to 150℃, end heating after 10h, take out the reactor and cool it naturally to room temperature, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 80℃ for 16h to obtain the catalyst, recorded as Mn3O4 / 4A.

[0045] Example 3

[0046] A manganese-based catalyst, the preparation method of which comprises:

[0047] Weigh 0.474g potassium permanganate (0.003mol) and 0.11g CTAB (0.0003mol), add 50mL water, stir for 10min to completely dissolve, add 1.65g 3A molecular sieve with an average particle size of 5mm, continue stirring for 30min, transfer the mixed solution to a 100mL polytetrafluoroethylene-lined reactor, seal the reactor and place it in a blast electric oven, set the temperature to 180℃, start timing when the oven temperature rises to 180℃, end heating after 16h, take out the reactor and cool it naturally to room temperature, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 100℃ for 20h to obtain the catalyst, recorded as Mn2O3 / 3A.

[0048] Comparative Example 1

[0049] A manganese-based catalyst, the preparation method of which comprises:

[0050] Weigh 0.3675 g of manganese acetate tetrahydrate (0.0015 mol) and 2.119 g of oleic acid (0.0075 mol), add 35 mL of ethanol and 35 mL of water, stir for 30 min to completely dissolve, transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined reactor, seal the reactor and place it in a blast electric oven, set the temperature to 120 ° C, start timing when the oven temperature rises to 120 ° C, end heating after 5 h, take out the reactor and cool it naturally to room temperature, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 60 ° C for 12 h to obtain the catalyst, recorded as MnO.

[0051] Comparative Example 2

[0052] A manganese-based catalyst, the preparation method of which comprises:

[0053] Weigh 0.395g potassium permanganate (0.0025mol) and 0.45g glucose (0.0025mol), add 65mL water, stir for 30min to completely dissolve it, transfer the mixed solution to a 100mL polytetrafluoroethylene-lined reactor, seal the reactor and place it in a blast electric oven, set the temperature to 150℃, start timing when the oven temperature rises to 150℃, end heating after 10h, take out the reactor and cool it naturally to room temperature, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 80℃ for 16h to obtain the catalyst, recorded as Mn3O4.

[0054] Comparative Example 3

[0055] A manganese-based catalyst, the preparation method of which comprises:

[0056] Weigh 0.474g potassium permanganate (0.003mol) and 0.11g CTAB (0.0003mol), add 50mL water, stir for 30min to completely dissolve it, transfer the mixed solution to a 100mL polytetrafluoroethylene-lined reactor, seal the reactor and place it in a blast electric oven, set the temperature to 180°C, start timing when the oven temperature rises to 180°C, end heating after 16h, take out the reactor and cool it naturally to room temperature, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 100°C for 20h to obtain the catalyst, recorded as Mn2O3.

[0057] Comparative Example 4

[0058] A manganese-based catalyst, the preparation method of which comprises:

[0059] Weigh 3.675g of manganese acetate tetrahydrate (0.015mol) and 4.238g of oleic acid (0.015mol), add 70mL of ethanol and 4mL of water, stir for 5min to completely dissolve it, add 0.825g of alumina with an average particle size of 0.1mm, continue stirring for 30min, transfer the mixed solution to a 100mL polytetrafluoroethylene-lined reactor, seal the reactor and place it in a blast electric oven, set the temperature to 120℃, start timing when the oven temperature rises to 120℃, end heating after 5h, take out the reactor and cool it naturally to room temperature, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 60℃ for 12h to obtain the catalyst, recorded as MnO / Al2O3-1.

[0060] Comparative Example 5

[0061] A manganese-based catalyst, the preparation method of which comprises:

[0062] Weigh 0.395g potassium permanganate (0.0025mol), add 65mL water, stir for 10min to completely dissolve it, add 1.375g 4A molecular sieve with an average particle size of 1mm, continue stirring for 30min, transfer the mixed solution to a 100mL polytetrafluoroethylene-lined reactor, seal the reactor and place it in a blast electric oven, set the temperature to 150℃, start timing when the oven temperature rises to 150℃, end heating after 10h, take out the reactor and cool it naturally to room temperature, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 80℃ for 16h to obtain the catalyst, recorded as MnO2 / 4A.

[0063] Comparative Example 6

[0064] A manganese-based catalyst, the preparation method of which comprises:

[0065] Weigh 0.3675g of manganese acetate tetrahydrate (0.0015mol) and 2.119g of oleic acid (0.0075mol), add 50mL of ethanol and 20mL of water, stir for 30min to completely dissolve, transfer the mixed solution to a 100mL polytetrafluoroethylene-lined reactor, seal the reactor and place it in a blast electric oven, set the temperature to 120℃, start timing when the oven temperature rises to 120℃, end heating after 5h, take out the reactor and cool it naturally to room temperature, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 60℃ for 12h to obtain MnO powder.

[0066] 0.825 g of aluminum oxide with an average particle size of 0.1 mm and 0.1065 g of MnO powder were weighed and placed in an agate mortar, and ground for physical uniform mixing, which was recorded as MnO / Al2O3-P.

[0067] Comparative Example 7

[0068] A manganese-based catalyst, the preparation method of which comprises:

[0069] Weigh 0.3675g of tetrahydrate manganese acetate (0.0015mol) and dissolve it in 150mL of water, stir for 30min to completely dissolve it to obtain a manganese acetate solution, then weigh 0.825g of aluminum oxide with an average particle size of 0.1mm and add it to the manganese acetate solution, stir for 30min to obtain a suspension. Add 25-28% ammonia water to the suspension while stirring until the pH of the suspension reaches 10, continue stirring and ageing for 3h, wash the precipitate alternately with water and ethanol several times, and finally dry it in an oven at 80°C for 16h to obtain a catalyst, which is recorded as MnO / Al2O3-A.

[0070] Application Examples

[0071] Weigh 1.0g of catalyst (the unloaded catalyst prepared in Comparative Examples 1 to 3 needs to be sieved through a 30-50 mesh sieve before being used in the catalytic reaction), activate it at 120°C for 12h under a vacuum environment, then fill the catalyst into a conversion device, and test the catalyst's catalytic performance of normal-parahydrogen conversion under different space velocities of hydrogen at 77K using a gas chromatograph equipped with a thermal conductivity detector. After the catalytic reaction starts, sample the parahydrogen content in hydrogen every 5 minutes until the parahydrogen ratio changes by less than 0.5% before and after, and start recording, and take the average value of 20 consecutive data. The results are as follows: Figure 2 As shown. After analysis, the supported catalysts obtained in Examples 1 to 3, although with different loads and different particle sizes, have significantly enhanced catalytic activity compared to the catalysts without carriers in Comparative Examples 1 to 3, and can still maintain a relatively high parahydrogen conversion rate when the hydrogen space velocity is greater. Compared with the MnO / Al2O3 prepared in Example 1, the MnO / Al2O3-1 prepared in Comparative Example 4 has an excessive amount of MnO loaded, resulting in insufficient exposure of active sites, and the catalytic activity is reduced. At the same time, the MnO / Al2O3-P prepared by the physical mixing method in Comparative Example 6 and the MnO / Al2O3-A obtained by the impregnation method in Comparative Example 7 have a certain improvement compared to pure MnO, but the improvement is far less than that of the MnO / Al2O3 obtained in Example 1, which shows that in the samples prepared by the solvothermal method, the active components are more closely combined with the carrier, and the catalytic effect and durability are better.

[0072] Table 1

[0073]

[0074] The catalysts prepared in Examples 1 to 3 above were compared with commercial iron oxide catalysts. The mechanical strength of the catalysts prepared in Examples 1 to 3 was tested, and the results are shown in Table 1. After analysis, it can be found that the mechanical strength of the catalysts prepared in Examples 1 to 3 is significantly higher than that of the commercial catalysts. Compared with the pure phase manganese oxide prepared in Comparative Examples 1 to 3, it is shown that the MnO / Al2O3, Mn3O4 / 4A, and Mn2O3 / 3A catalysts obtained after hydrothermal treatment still maintain the excellent mechanical strength of the carrier, can withstand the long-term erosion of hydrogen flow, and have a longer life.

[0075] The catalysts prepared in the above examples and comparative examples were subjected to XRD testing, and the results are as follows: Figure 1 After analysis, the pure phase MnO, Mn2O3, and Mn3O4 synthesized in Comparative Examples 1 to 3 match the standard cards, while the XRD diffraction peaks of the catalysts prepared in Examples 1 to 3 and Comparative Examples 4 to 7 after adding the carrier are basically consistent with those of the carrier, which on the one hand shows that the loading amount of manganese oxide is low and evenly distributed, and on the other hand also shows that the grain size of manganese oxide is small.

[0076] XPS test was performed on the Mn element in the catalysts MnO / Al2O3, Mn3O4 / 4A, Mn2O3 / 3A and MnO2 / 4A prepared in Example 1, Example 2, Example 3 and Comparative Example 5. The results are as follows: Figure 3 As shown. After analysis, it can be found that due to the different valence states of the Mn element in the four catalysts, the binding energy of the Mn element is different, and the higher the valence state, the greater the binding energy. Among them, the manganese element in MnO2 / 4A prepared in Comparative Example 5 exists in the form of +4 valence. Figure 2 It can be seen that the catalytic activity is much lower than that of manganese elements in +2 and +3 valence forms in MnO / Al2O3, Mn3O4 / 4A, and Mn2O3 / 3A.

[0077] SEM tests were performed on the 4A molecular sieve (a-c) and the catalyst Mn3O4 / 4A (d-f) prepared in Example 2. The results are as follows: Figure 4 After analysis, it is found that the 4A molecular sieve has good hydrothermal stability. Long-term hydrothermal treatment does not change its particle size. However, after treatment, the surface of the molecular sieve is evenly covered with a layer of manganese oxide. From the EDS-mapping diagram (g~i) of the catalyst Mn3O4 / 4A, it can be found that the distribution of manganese and oxygen elements on the surface of the molecular sieve is very uniform, proving the close combination of manganese oxide and the molecular sieve.

[0078] It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a manganese oxide-based parahydrogen conversion catalyst, characterized in that: The method includes: A manganese source, a reaction aid and a carrier are mixed in a reaction solvent, and then subjected to solvent thermal treatment to obtain a manganese oxide-based ortho-parahydrogen conversion catalyst.

2. The method for preparing the manganese oxide-based para-hydrogen conversion catalyst according to claim 1, characterized in that: The manganese source is selected from at least one of manganese acetate, potassium permanganate, manganese sulfate or manganese nitrate.

3. The method for preparing the manganese oxide-based para-hydrogen conversion catalyst according to claim 1, characterized in that: The concentration of the manganese element in the manganese source in the reaction solvent is 0.01-1 mol / L.

4. The method for preparing the manganese oxide-based para-hydrogen conversion catalyst according to claim 1, characterized in that: The reaction aid is selected from at least one of glucose, oleic acid or hexadecyltrimethylammonium bromide; the molar ratio of the reaction aid to the manganese element in the manganese source is (1-10):

1.

5. The method for preparing the manganese oxide-based para-hydrogen conversion catalyst according to claim 1, characterized in that: The carrier is selected from at least one of alumina, molecular sieve, activated carbon or silicon dioxide, and the particle size of the carrier is 0.1 to 5 mm.

6. The method for preparing the manganese oxide-based para-hydrogen conversion catalyst according to claim 1, characterized in that: The mass ratio of the carrier to the manganese element in the manganese source is (5-20):

1.

7. The method for preparing a manganese oxide-based ortho-parahydrogen conversion catalyst according to claim 1, characterized in that: The reaction solvent is selected from at least one of water, ethanol or ethylene glycol; preferably, the reaction solvent is a mixture of ethanol or ethylene glycol and water in a volume ratio of 5:(1-3).

8. The method for preparing a manganese oxide-based ortho-parahydrogen conversion catalyst according to claim 1, characterized in that: In the solvent thermal treatment, the treatment temperature is 100 to 200° C. and the treatment time is 3 to 18 hours.

9. An application of a manganese oxide-based ortho-parahydrogen conversion catalyst prepared by the method according to any one of claims 1 to 8, characterized in that: The manganese oxide-based para-hydrogen conversion catalyst is used for para-hydrogen conversion reaction.

10. The use of the manganese oxide-based para-hydrogen conversion catalyst according to claim 1, characterized in that: Before the ortho-parahydrogen conversion catalytic reaction, the catalyst is activated in a vacuum environment at 100-140° C. for 10-14 hours; In the catalytic reaction of ortho-parahydrogen conversion, the reaction temperature is 70-80K and the space velocity is 10000-60000h -1 The reaction time is 24 to 480 hours.

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