Supported MnCo-based catalyst and preparation method thereof, and purification method of hydrogen-containing gas

Abstract

The invention relates to the field of catalyst preparation, and discloses a supported MnCo-based catalyst and a preparation method thereof, and a purification method of hydrogen-containing gas. The invention relates to a preparation method of a supported MnCo-based catalyst, which comprises the following steps: (1) carrying out hydroxylation treatment on a carrier, and then carrying out first drying and first roasting to obtain a hydroxylated carrier; and (2) reacting the hydroxylated carrier with a manganese precursor and a cobalt precursor in the presence of a solvent, and then carrying out second drying and optional second roasting. According to the preparation method, hydroxylation treatment and a chemical reduction method are combined to prepare the catalyst, the utilization rate of an active center is increased, and the purification effect of hydrogen-containing gas is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and particularly relates to a supported MnCo-based catalyst, a preparation method thereof, and a method for purifying hydrogen-containing gas. Background Art

[0002] Helium is a noble gas that usually exists in trace amounts in natural gas and some radioactive ores. In industrial and scientific fields, high-purity helium is commonly used for gas filling, protective atmospheres, gas chromatography, and other laboratory applications. However, naturally occurring helium is usually mixed with other gases, such as nitrogen, hydrogen, and argon. Therefore, in order to obtain high-purity helium, a helium purification process is required. Generally, helium purification usually employs different processes such as adsorption, membrane separation, and chemical absorption. Physical methods such as adsorption separation can remove most of the impurities, but since the molecular sizes of hydrogen and helium are similar, the energy consumption for removing hydrogen using physical methods is very high. Therefore, the purification of hydrogen and helium can use the method of catalytic oxidation to remove.

[0003] Supported MnCo-based catalytic oxidation catalysts are widely used in various oxidation reactions, such as organic waste gas treatment, wastewater treatment, and purification of atmospheric pollutants. Manganese cobalt (MnCo) is selected as the active component because both manganese and cobalt have good oxidation catalytic activity. The synergistic effect of manganese and cobalt can improve the stability and activity of the catalyst.

[0004] Patent application CN116116425A discloses a manganese cobalt-based catalyst, a preparation method thereof, and an application. A manganese cobalt-based catalyst is provided, which includes a carrier and an active component, and the active component includes Mn and Co; in the catalyst, the content of Mn is 10-20 wt%, and the content of Co is 10-15 wt%; the carrier is impregnated with a precursor solution II obtained by mixing an active component source and an acid reagent, and then subjected to drying treatment and calcination treatment in sequence to obtain the catalyst. The catalyst obtained by this method is a mixed phase, containing MnO2, Co3O4, and MnCo2O4, and cannot fully utilize all active centers. Summary of the Invention

[0005] The object of the present invention is to overcome the technical problems existing in the prior art, and provide a supported MnCo-based catalyst, a preparation method and an application thereof, and a method for purifying hydrogen-containing gas. This preparation method combines hydroxylation treatment and chemical reduction method to prepare the catalyst, improving the utilization rate of active centers and the purification effect of hydrogen-containing gas.

[0006] To achieve the above object, the first aspect of the present invention provides a preparation method of a supported MnCo-based catalyst, wherein the method includes the following steps:

[0007] (1) Hydroxylate the support, then perform the first drying and the first calcination to obtain a hydroxylated support;

[0008] (2) React the hydroxylated support with a manganese precursor and a cobalt precursor in the presence of a solvent, then perform the second drying and optionally the second calcination.

[0009] The second aspect of the present invention provides a supported MnCo-based catalyst prepared by the preparation method described in the first aspect.

[0010] The third aspect of the present invention provides a method for purifying a hydrogen-containing gas, wherein the method comprises contacting the hydrogen-containing gas with the supported MnCo-based catalyst described in the second aspect for purification.

[0011] In the preparation method provided by the present invention, the surface of the support is hydroxylated. After hydroxylation, the surface of the hydroxylated support contains a large number of silicon-containing functional groups, and it is easier to generate hydroxyl functional groups in an aqueous environment. The hydroxyl functional groups attract the complexed metal cations, uniformly dispersing the active centers on the surface of the support, which is beneficial to improving the dispersion degree of the active centers, increasing the utilization rate of the active centers, enhancing the purification effect of the hydrogen-containing gas, and effectively removing hydrogen in the hydrogen-containing gas. In a preferred case, the method provided by the present invention can reduce the hydrogen in the hydrogen tail gas from 10 ppm to 10 ppb.

[0012] The supported MnCo-based catalyst prepared by the preparation method provided by the present invention has good catalytic activity. In a preferred case, it is particularly suitable for the purification reaction of hydrogen-containing gas with a low flow rate. Description of the Drawings

[0013] Figure 1 Scanning electron microscope photograph of the supported MnCo-based catalyst prepared in Example 1. Detailed Description of the Invention

[0014] The endpoints and any values disclosed in this article for a range are not limited to the exact range or value. These ranges or values should be understood to include values close to these ranges or values. For a numerical range, the endpoints of each range, between the endpoints of each range and a single point value, and between single point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0015] The first aspect of the present invention provides a method for preparing a supported MnCo-based catalyst, wherein the method comprises the following steps:

[0016] (1) Hydroxylate the support, then perform the first drying and the first calcination to obtain a hydroxylated support;

[0017] (2) In the presence of a solvent, react the hydroxylated support with a manganese precursor and a cobalt precursor, and then perform a second drying and optionally a second calcination.

[0018] The preparation method provided by the present invention performs a hydroxylation treatment on the surface of the support. After the hydroxylation treatment, the surface of the hydroxylated support contains a large number of silicon-containing functional groups, and it is easier to generate hydroxyl functional groups in an aqueous environment. The hydroxyl functional groups attract the complexed metal cations, uniformly dispersing the active centers on the surface of the support, which is beneficial to improving the dispersion degree of the active centers, enhancing the utilization rate of the active centers, improving the purification effect of the hydrogen-containing gas, and effectively removing hydrogen in the hydrogen-containing gas. In a preferred case, the method provided by the present invention can reduce the hydrogen in the hydrogen-containing gas from 10 ppm to 10 ppb.

[0019] In the present invention, taking the support as the initial loading core and performing a hydroxylation treatment on it can improve the dispersion degree of the active centers. The present invention has a wide range of choices for the type of support, which can be the supports conventionally defined in the art. Preferably, the support is a heat-resistant inorganic oxide and / or a molecular sieve.

[0020] In the present invention, there is no particular limitation on the specific type of the heat-resistant inorganic oxide, and any heat-resistant inorganic oxide conventionally defined in the art can be applicable to the present invention. Preferably, the heat-resistant inorganic oxide is selected from at least one of alumina, silica, titanium oxide, cerium oxide, lanthanum oxide, and zirconium oxide, and more preferably alumina.

[0021] In the present invention, there is no particular limitation on the specific type of the molecular sieve. Preferably, the molecular sieve is selected from at least one of X-type molecular sieve, Y-type molecular sieve, and β-type molecular sieve.

[0022] In the present invention, there is no particular limitation on the shape of the support. For example, it can be at least one of spherical, granular, bar-shaped, and butterfly-shaped, and preferably spherical.

[0023] According to a preferred embodiment of the present invention, the support is spherical, and preferably the diameter of the support is 2 - 10 mm.

[0024] According to a preferred embodiment of the present invention, the specific surface area of the support is 150 - 300 m 2 / g.

[0025] In the present invention, there is no particular limitation on the specific manner of hydroxylation treatment. For example, it can be a treatment that can achieve the hydroxylation of the carrier surface as conventionally defined in the art. Preferably, the hydroxylation treatment adopts at least one of hydrothermal treatment, ion exchange method, and chemical reactions including alcoholization, etherification or esterification, and is preferably hydrothermal treatment. By adopting hydrothermal treatment, the hydroxylation treatment of the carrier surface can be realized, which will not have an adverse effect on the specific surface area of the catalyst, the change of the specific surface area of the catalyst is small, and the cost can be saved, having good industrial value.

[0026] According to a preferred embodiment of the present invention, in step (1), the hydrothermal treatment includes: in the presence of an aqueous medium, subjecting the carrier to hydrothermal treatment to obtain a hydroxylated carrier.

[0027] In the present invention, there is no particular limitation on the type of the aqueous medium, as long as it can provide the solvent for the hydrothermal treatment. Preferably, in step (1), the aqueous medium is provided by water and / or an atmosphere containing water vapor, and more preferably an atmosphere containing water vapor.

[0028] In the present invention, there is no particular limitation on the type of the atmosphere containing water vapor, as long as it can provide steam conditions. Preferably, in step (1), the atmosphere containing water vapor further contains at least one of air, methanol, ethanol and formic acid, and more preferably further contains air. The advantage of adopting this preferred embodiment is that the process is simple and the materials are cheap.

[0029] In the present invention, there is no particular limitation on the content of each component in the atmosphere containing water vapor. Preferably, in step (1), based on the total volume of the atmosphere containing water vapor, in the atmosphere containing water vapor, the content of the water vapor is 10-80% by volume, and more preferably 40-80% by volume. The advantage of adopting this preferred embodiment is that the water vapor concentration is appropriate, which can improve the effect of the hydroxylation treatment. If the water vapor concentration is too low, the hydroxylation treatment effect is not good, and if the concentration is too high, it is not easy to introduce the carrier gas.

[0030] In the present invention, there is no particular limitation on the conditions of the hydroxylation treatment. When the hydroxylation treatment is carried out in the presence of water, according to a preferred embodiment of the present invention, in step (1), the conditions of the hydroxylation treatment include: the temperature is 110-300 °C, the time is 2-12 hours, and relative to 1 g of the carrier, the amount of water used is 1-20 mL.

[0031] In the present invention, there is no particular limitation on the conditions of the hydroxylation treatment. When the hydroxylation treatment is carried out in the presence of an atmosphere containing water vapor, according to another preferred embodiment of the present invention, in step (1), the conditions of the hydroxylation treatment include: the temperature is 180-300 °C, the time is 3-8 hours, and the volume space velocity of the atmosphere containing water vapor is 1000-3000 h-1 。

[0032] In the present invention, there is no particular limitation on the equipment used for the hydroxylation treatment in step (1). For example, it can be carried out in a fixed-bed reactor or in a reaction kettle.

[0033] In the present invention, the selection range of the conditions for the first drying in step (1) is relatively wide. Preferably, in step (1), the conditions for the first drying include: the temperature is 100 - 150 °C, and the time is 2 - 4 hours.

[0034] In the present invention, the selection range of the conditions for the first calcination in step (1) is relatively wide. Preferably, in step (1), the conditions for the first calcination include: the temperature is 200 - 550 °C, and the time is 2 - 4 hours.

[0035] In the present invention, by combining the carrier hydroxylation reaction and the chemical reaction for loading the manganese-cobalt composite oxide, the dispersion degree and utilization rate of the active centers are improved, and the catalytic performance of the MnCo-based catalyst is enhanced. Preferably, in step (2), the reaction is a redox reaction, and the manganese-cobalt composite oxide is obtained on the surface of the hydroxylated carrier.

[0036] In the present invention, the special morphology and composition of the manganese-cobalt composite oxide are more conducive to the highly dispersed subsequent noble metals, and are more conducive to improving the catalytic activity of the supported MnCo-based catalyst. Preferably, the morphology of the manganese-cobalt composite oxide is spherical or quasi-spherical particles formed by the cross-stacking of rod-like structures.

[0037] In the present invention, preferably, the size (also referred to as the diameter) of the spherical or quasi-spherical particles is 200 nm - 2 μm, and more preferably 200 nm - 500 nm.

[0038] In the present invention, preferably, the length of the rod-like structure is 20 nm - 200 nm.

[0039] In the present invention, the morphology of the manganese-cobalt composite oxide is obtained by scanning electron microscopy testing.

[0040] In the present invention, preferably, the manganese-cobalt composite oxide includes MnCo2O4 and MnO2.

[0041] In the present invention, preferably, the surface layer of the rod-like structure is MnO2, and the interior is MnCo2O4. More preferably, the thickness of the MnO2 surface layer of the rod-like structure is 1 nm - 3 nm.

[0042] In the present invention, the morphology of the sample was observed by STEM and the particle size distribution was used to statistically analyze the particle size. The elemental distribution of the sample was observed by EDS. A JEM-F200 field emission transmission electron microscope of JEOL was used. Operating conditions: The acceleration voltage was 200 kV. Before the test, a small amount of powder sample was ultrasonically dispersed in absolute ethanol and dropped onto a copper grid with a capillary, and then dried before the test.

[0043] In the present invention, preferably, based on the metal element, the molar ratio of the manganese precursor to the cobalt precursor is 0.1-2, and more preferably 0.4-0.8.

[0044] In the present invention, there is no particular limitation on the type of the manganese precursor in step (2). Any manganese-containing compound capable of undergoing an oxidation-reduction reaction as defined in the art is applicable to the present invention. Preferably, the manganese precursor is provided by potassium permanganate.

[0045] In the present invention, there is no particular limitation on the type of the cobalt precursor in step (2). Any cobalt-containing compound capable of undergoing an oxidation-reduction reaction as defined in the art is applicable to the present invention. Preferably, the cobalt precursor is provided by a divalent cobalt salt, and more preferably selected from at least one of cobalt nitrate, cobalt chloride and cobalt sulfate.

[0046] In the present invention, the selection range of the type of the solvent in step (2) is relatively wide, as long as it provides the environment for the reaction. Preferably, the solvent is water.

[0047] According to a preferred embodiment of the present invention, the reaction in step (2) includes: contacting the hydroxylated support with a solution containing a manganese precursor, and then adding a cobalt precursor for reaction. Adopting this preferred embodiment is more conducive to the progress of the oxidation-reduction reaction and more conducive to obtaining a supported MnCo-based catalyst with improved performance.

[0048] In the present invention, preferably, the concentration of the solution containing the manganese precursor is 0.1-0.3 mol / L.

[0049] In the present invention, preferably, the way of contacting the hydroxylated support with the solution containing the manganese precursor in step (2) is to immerse the hydroxylated support in the solution containing the manganese precursor.

[0050] In the present invention, preferably, the cobalt precursor is added in the form of a solution containing the cobalt precursor.

[0051] In the present invention, preferably, the concentration of the solution containing the cobalt precursor is 1-8 times the concentration of the solution containing the manganese precursor.

[0052] In the present invention, the addition rate of the solution containing the cobalt precursor has a relatively wide selection range, which is based on facilitating the progress of the redox reaction. Preferably, the addition rate of the solution containing the cobalt precursor is 0.5-1% of the total volume of the solution containing the cobalt precursor introduced per minute.

[0053] According to a preferred embodiment of the present invention, step (2) includes contacting the hydroxylated support with the solution containing the manganese precursor, then heating to the reaction temperature, and then adding the cobalt precursor for reaction.

[0054] In the present invention, the reaction conditions in step (2) have a relatively wide selection range. Preferably, the reaction conditions include: the temperature is 50-90°C, preferably 60-80°C, and the time is 1-6 hours, preferably 2-4 hours. The reaction time is measured from the completion of the addition of the cobalt precursor.

[0055] In the present invention, for more facilitating the progress of the redox reaction, preferably, the step of adding the cobalt precursor in step (2) is carried out under oscillating conditions. The present invention has a relatively wide selection range for the oscillating conditions. Preferably, the oscillation frequency is 60-180 times per minute.

[0056] In the present invention, specifically, the method further includes a washing step before the second drying in step (2). The washing can be carried out by conventional technical means in the art, and the present invention has no special limitation on this.

[0057] In the present invention, the conditions for the second drying in step (2) have a relatively wide selection range. Preferably, in step (2), the conditions for the second drying include: the temperature is 100-150°C, and the time is 8-24 hours.

[0058] In the present invention, the conditions for the second calcination in step (2) have a relatively wide selection range. Preferably, in step (2), the conditions for the second calcination include: the temperature is 400-550°C, and the time is 2-4 hours.

[0059] In the present invention, by loading noble metals as one of the active components, the hydrogen activity is assisted, and the reaction temperature for the purification of hydrogen-containing gases is reduced. Preferably, the method further includes step (3): impregnating the second calcination product obtained in step (2) in an impregnating solution containing a noble metal precursor, adjusting the pH to alkaline, preferably adjusting to pH 8-9, standing and then heating, and then performing the third drying and the third calcination.

[0060] In the present invention, the types of noble metals have a relatively wide selection range. Preferably, in step (3), the noble metal is selected from at least one of platinum, palladium, rubidium, and rhodium, and further preferably platinum and palladium. The present invention has a relatively wide selection range for the ratio of platinum and palladium. For example, it can be 1:0.1-10.

[0061] In the present invention, preferably, in step (3), the impregnating solution containing the noble metal precursor is provided by a salt solution of the noble metal, preferably provided by a nitrate solution and / or a chlorate solution.

[0062] In the present invention, there is no particular limitation on the concentration of the impregnating solution containing the noble metal precursor. Preferably, in step (3), the concentration of the impregnating solution containing the noble metal precursor is 0.1-4 g / L.

[0063] In the present invention, preferably, in step (3), the conditions for standing still include: the time is 1-6 hours.

[0064] In the present invention, preferably, in step (3), the conditions for heating include: the temperature is 50-80 °C and the time is 1-6 hours.

[0065] In the present invention, ammonia water can be used to adjust the pH to alkaline. Preferably, the concentration of the ammonia water is 0.5-1 mol / L.

[0066] In the present invention, the selection range of the conditions for the third drying is relatively wide. Preferably, in step (3), the conditions for the third drying include: the temperature is 100-150 °C and the time is 12-24 hours.

[0067] In the present invention, the selection range of the conditions for the third calcination is relatively wide. Preferably, in step (3), the conditions for the third calcination include: the temperature is 400-500 °C and the time is 2-4 hours.

[0068] In the present invention, there is no particular limitation on the amounts of the carrier, the manganese precursor, and the cobalt precursor. Preferably, the amounts of the carrier, the manganese precursor, and the cobalt precursor are such that in the second calcined product obtained, based on the total amount of the second calcined product, the content of the hydroxylated carrier is 85-95 wt%, and the content of the manganese-cobalt composite oxide is 5-15 wt%; further preferably, the content of the hydroxylated carrier is 88-92 wt%, and the content of the manganese-cobalt composite oxide is 8-12 wt%.

[0069] In the present invention, the content of the manganese-cobalt oxide is obtained by testing the content of metal elements by an inductively coupled plasma emission spectrometer (ICP) and then converting it to the content of the oxide. Specifically, an AVIO500 type inductively coupled plasma emission spectrometer of PerkinElmer Company in the United States can be used. Before testing, it is digested with aqua regia, and the solid-liquid ratio is 1:3 at 50 degrees until it becomes clear.

[0070] In the present invention, preferably, the amounts of the manganese precursor and the cobalt precursor are such that in the second calcined product obtained, based on the total amount of the second calcined product, the content of part of Mn and Co calculated as MnCo₂O₄ is 5-14.9 wt%, and the content of the remaining part of Mn calculated as MnO₂ is 0.01-0.2 wt%; more preferably, the content of part of Mn and Co calculated as MnCo₂O₄ is 8-11.9 wt%, and the content of the remaining part of Mn calculated as MnO₂ is 0.05-0.1 wt%. In the present invention, a smaller amount of Mn and Co is used, and high catalytic performance can still be obtained, and the phenomenon of pore blockage caused by a large content of Mn and Co is avoided.

[0071] In the present invention, the content of part of Mn and Co calculated as MnCo₂O₄ and the content of the remaining part of Mn calculated as MnO₂ are obtained by ICP testing. Specifically, an AVIO 500 type inductively coupled plasma emission spectrometer of PerkinElmer Company in the United States can be used. Before testing, digest with aqua regia, with a solid-liquid ratio of 1:3 and at 50 °C until it becomes clear. Among them, part of Mn exists in the form of MnO₂, and part of Mn and Co exist in the form of MnCo₂O₄. The contents of Co and Mn are obtained by ICP testing, and then the content of part of Mn and Co calculated as MnCo₂O₄ is calculated through Co. The difference between the content of Mn obtained by ICP testing and the amount of Mn existing in the form of MnCo₂O₄ is the content of the remaining part of Mn calculated as MnO₂.

[0072] In the present invention, preferably, the amount of the impregnating solution containing the noble metal precursor is such that in the supported MnCo-based catalyst obtained, based on the total volume of the supported MnCo-based catalyst, the content of the noble metal calculated as an element is 0.1-4 g / L.

[0073] In the present invention, the content of the noble metal is measured by ICP testing.

[0074] In the present invention, preferably, steps (1) and (2) are such that the supported MnCo-based catalyst obtained contains active oxygen. In the present invention, the combination of hydroxylation treatment and chemical reduction treatment makes the supported MnCo-based catalyst obtained contain active oxygen, which is beneficial to the purification reaction of hydrogen-containing gases.

[0075] In the present invention, preferably, based on the total amount of the supported MnCo-based catalyst, the content of the active oxygen is 300-900 μmol / gcat, and more preferably 550-750 μmol / gcat.

[0076] In the present invention, the content of the active oxygen is obtained by the H2-TPR method. The reduction peak signal of H2 for the catalyst is collected, and the total molar number of H2 obtained by integrating the signal before 350 °C is compared with the amount of the catalyst used to obtain the content of the active oxygen. Test conditions: 1% hydrogen uses helium as the filling gas. The chemical adsorption instrument is used to pass through the fixed bed layer filled with the catalyst, and the process of reducing the catalyst is heated from room temperature to 500 °C at a rate of 1 °C per minute. The TCD detector is used to check the change of the H2 concentration, and the total molar number of H2 is calculated by integrating the hydrogen consumption.

[0077] In the second aspect of the present invention, a supported MnCo-based catalyst prepared by the method described in the first aspect is provided. Preferably, the supported MnCo-based catalyst contains active oxygen.

[0078] In the present invention, preferably, based on the total amount of the supported MnCo-based catalyst, the content of the active oxygen is 300-900 μmol / gcat, and more preferably 550-750 μmol / gcat.

[0079] In the third aspect of the present invention, a method for purifying a hydrogen-containing gas is provided, wherein the method includes contacting the hydrogen-containing gas with the supported MnCo-based catalyst described in the second aspect for purification.

[0080] The supported catalyst prepared by the preparation method provided by the present invention has broad application prospects in the field of catalytic oxidation, and is particularly suitable for the purification reaction of hydrogen-containing gases with low flow rates, effectively improving the removal efficiency of hydrogen in the hydrogen-containing gas, greatly reducing the content of hydrogen in the hydrogen-containing gas, and realizing the effective removal of hydrogen.

[0081] In the present invention, the selection range of the types of hydrogen-containing gases is relatively wide. Preferably, the hydrogen-containing gas further contains at least one of helium, carbon monoxide, methane, and nitrogen, and more preferably helium.

[0082] In the present invention, there is no particular limitation on the content of each component in the hydrogen-containing gas. Preferably, based on the total amount of the hydrogen-containing gas, the concentration of hydrogen in the hydrogen-containing gas is 10-100 ppm. The advantage of adopting this preferred embodiment is that low-concentration gases are more suitable for this method, and high-concentration gases will rapidly reduce the surface active oxygen, resulting in the need for frequent oxidative regeneration of the catalyst.

[0083] In the present invention, preferably, the conditions for the contact include: the temperature is 200-400 °C, and the volume space velocity of the hydrogen-containing gas is 1000-6000 h -1 .

[0084] The method provided by the present invention selects the supported MnCo-based catalyst prepared by the preparation method of the present invention to remove hydrogen in the hydrogen-containing gas, which can improve the purification effect of the hydrogen-containing gas and effectively reduce the concentration of hydrogen in the hydrogen-containing gas. In a preferred case, the method provided by the present invention can reduce the hydrogen in the hydrogen gas from 10 ppm to 10 ppb.

[0085] The present invention will be described in detail below through examples. Unless otherwise specified, the raw materials used in the following examples are all commercially available products.

[0086] The specific surface area of the sample was measured by a physical adsorption instrument in the present invention, and an AUTO-SORB-1-MP type analyzer of Quantachrome Corporation of the United States was used. Operating conditions: Before testing, the sample was vacuum degassed at 300 °C for 6 hours on the external degassing station. Subsequently, nitrogen was used as the adsorbate, and the adsorption and desorption tests were carried out at the liquid ammonia temperature (77 K). The specific surface area of the sample was calculated by the Bninauer-Emmett-Teller (BET) method.

[0087] Example 1

[0088] (1) 60 g of alumina spheres (2 mm in diameter, specific surface area 200 m 2 / g) were added to a fixed-bed reactor, and air containing water vapor was introduced at 300 °C. The proportion of water vapor was 50 vol%, and the introduction time was 4 hours. The volume space velocity of the air containing water vapor was 2000 h -1 .

[0089] (2) The treated alumina spheres obtained in step (1) were dried at 110 °C for 12 hours and then calcined at 250 °C for 3 hours to obtain a hydroxylated alumina support.

[0090] (3) The hydroxylated alumina support obtained in step (2) was impregnated in 100 mL of a 0.2 mol / L potassium permanganate solution, then heated to 70 °C, and 50 mL of a 0.8 mol / L cobalt nitrate solution was added dropwise. During the process, a beaker oscillator was used to oscillate at a frequency of 60 times / minute, and then it was allowed to stand for 4 hours and taken out, purged with dry air for 2 hours, and then dried at 110 °C for 8 hours to obtain MnCo-based catalyst A.

[0091] Based on the total amount of MnCo-based catalyst A, the content of the hydroxylated alumina support is 90 wt%, the content of the manganese-cobalt composite oxide is 10 wt%, the content of part of Mn and Co in terms of MnCo2O4 is 9.9 wt%, and the content of the remaining part of Mn in terms of MnO2 is 0.1 wt%.

[0092] Based on the total amount of MnCo-based catalyst A, the content of active oxygen is 500 μmol / gcat.

[0093] It can be seen from Figure 1 that the morphology of the manganese-cobalt composite oxide is spherical or quasi-spherical particles formed by the cross-stacking of rod-like structures.

[0094] It is known from scanning and STEM analysis that spherical particles of manganese-cobalt composite oxide are uniformly loaded on the surface of the hydroxylated alumina support. The diameter of the spherical particles is 200-400 nm. The length of the rod-like structures on the surface of the spherical particles is 50-150 nm. The inside of the rod-like structures is MnCo2O4, and the outer layer is MnO2 with a thickness of 1-3 nm.

[0095] Example 2

[0096] (1) Add 60 g of alumina spheres (2 mm in diameter, specific surface area 200 m 2 / g) to a 200 mL autoclave, add water to 150 mL, the temperature is 180 °C, and the time is 4 h.

[0097] Steps (2)-(3) are the same as those in Example 1 to obtain MnCo-based catalyst B.

[0098] Based on the total amount of MnCo-based catalyst B, the content of the hydroxylated alumina support is 92 wt%, the content of the manganese-cobalt composite oxide is 8 wt%, the content of part of Mn and Co calculated as MnCo2O4 is 7.9 wt%, and the content of the remaining part of Mn calculated as MnO2 is 0.08 wt%.

[0099] Based on the total amount of MnCo-based catalyst B, the content of active oxygen is 450 μmol / gcat.

[0100] Example 3

[0101] Steps (1)-(3) are the same as those in Example 1 to obtain MnCo-based catalyst A.

[0102] (4) Prepare 100 mL of a platinum nitrate solution with a concentration of 1.5 g / L of platinum;

[0103] (5) Immerse the MnCo-based catalyst A obtained in step (3) in the solution in step (4), add concentrated ammonia water to adjust the pH to 8-9, and then let it stand for 2 hours;

[0104] (6) Heat the solution after standing in step (5) to 60 °C and keep it for 1 hour;

[0105] (7) Take out the honeycomb ceramic catalyst, rinse it 3 times with water, then dry it in an oven at 110 °C for 12 hours, and then calcine it in a muffle furnace at 450 °C for 4 hours to obtain Pt-MnCo-based catalyst A.

[0106] Based on the total amount of Pt-MnCo-based catalyst A, the content of active oxygen is 640 μmol / gcat.

[0107] Example 4

[0108] According to the method of Example 3, replace the platinum solution in step (4) with a palladium solution to obtain Pd-MnCo-based catalyst B.

[0109] Based on the total amount of Pd-MnCo-based catalyst B, the content of active oxygen is 635 μmol / gcat.

[0110] Example 5

[0111] (1) Add 60 g of alumina spheres (2 mm in diameter, specific surface area 200 m 2 / g) to a fixed-bed reactor, and introduce air containing water vapor at 250 °C. The proportion of water vapor is 80% by volume, and the introduction time is 3 hours. The volume space velocity of the air containing water vapor is 3000 h -1 .

[0112] (2) Dry the treated alumina spheres obtained in step (1) at 110 °C for 12 hours, and then calcine them at 300 °C for 3 hours to obtain a hydroxylated alumina support.

[0113] (3) Immerse the hydroxylated alumina support obtained in step (2) in 100 mL of a 0.2 mol / L potassium permanganate solution, then heat it to 75 °C, and gradually add 50 mL of a 0.6 mol / L cobalt nitrate solution. During the process, use a beaker oscillator to oscillate at a frequency of 60 times / minute, then keep it standing for 6 hours and take it out, purge it with dry air for 2 hours, and then dry it at 110 °C for 8 hours to obtain MnCo-based catalyst C.

[0114] Based on the total amount of MnCo-based catalyst C, the content of the hydroxylated alumina support is 91 wt%, the content of the manganese-cobalt composite oxide is 9 wt%, the content of part of Mn and Co calculated as MnCo2O4 is 8.9 wt%, and the content of the remaining part of Mn calculated as MnO2 is 0.1 wt%.

[0115] (4) Prepare 100 mL of a platinum nitrate solution with a concentration of 1.5 g / L of platinum;

[0116] (5) Immerse the MnCo-based catalyst C obtained in step (3) in the solution of step (4), add concentrated ammonia water to adjust the pH to 8 - 9, and then let it stand for 3 hours;

[0117] (6) Heat the solution after standing in step (5) to 70 °C and keep it for 2 hours;

[0118] After taking out the honeycomb ceramic catalyst, it was rinsed with water 5 times, then dried in an oven at 110 °C for 12 hours, and then calcined in a muffle furnace at 400 °C for 4 hours to obtain the Pt-MnCo-based catalyst C.

[0119] Based on the total amount of the Pt-MnCo-based catalyst C, the content of active oxygen was 550 μmol / gcat.

[0120] Example 6

[0121] According to the method of Example 3, the difference is that in step (3), the potassium permanganate solution and the cobalt nitrate solution were added simultaneously, and the reaction was carried out in an autoclave at 180 °C and 8 MPa pressure to obtain the MnCo-based catalyst D, and subsequently the Pt-MnCo-based catalyst D was obtained.

[0122] Based on the total amount of the MnCo-based catalyst D, the content of the hydroxylated alumina support was 91 wt%, the content of the manganese-cobalt composite oxide was 9 wt%, the content of part of Mn and Co in terms of MnCo2O4 was 8.9 wt%, and the content of the remaining part of Mn in terms of MnO2 was 0.15 wt%.

[0123] Based on the total amount of the Pt-MnCo-based catalyst D, the content of active oxygen was 557 μmol / gcat.

[0124] Comparative Example 1

[0125] According to the method of Example 1, the difference is that step (1) was not carried out, and the other steps were the same as those in Example 1 to obtain the MnCo-based catalyst E.

[0126] Based on the total amount of the MnCo-based catalyst E, the content of active oxygen was 150 μmol / gcat.

[0127] The parameters of the catalysts prepared in the above examples and comparative examples are shown in Table 1.

[0128] Table 1

[0129] Catalyst <![CDATA[Specific surface area m 2 / g]]> Noble metal content g / L Example 1 MnCo-based catalyst A 185 0 Example 2 MnCo-based catalyst B 182 0 Example 3 Pt-MnCo-based catalyst A 185 2.1 Example 4 Pd-MnCo-based catalyst B 185 2.1 Example 5 Pt-MnCo-based catalyst C 184 2.0 Example 6 Pt-MnCo-based catalyst D 181 2.0 Comparative Example 1 MnCo-based catalyst E 190 0

[0130] Test Example

[0131] The catalysts prepared in the examples and comparative examples were applied to the helium purification reaction to remove hydrogen in helium, and the reaction was carried out in a fixed-bed reactor of a medium-sized reaction evaluation device. The catalyst filling amount was 100 mL, the bed height was 10 cm, the initial hydrogen concentration was 100 ppm, the carrier gas was helium, and the volumetric space velocity was 1000 h -1After the reaction continued for 2 hours, the temperature was lowered to 100 °C, and a nitrogen carrier gas containing 1% by mass of oxygen was introduced for 10 minutes. Subsequently, it continued to be recycled. The hydrogen concentration was measured by an Agilent 7890A gas chromatograph, and the test results are shown in Table 2.

[0132] Table 2

[0133]

[0134] As can be seen from Table 2 above, the catalyst in the example can still maintain good hydrogen conversion efficiency after being recycled 50 times.

[0135] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing a supported MnCo-based catalyst, wherein, The method includes the following steps: (1) Hydroxylate the support, then perform the first drying and the first calcination to obtain a hydroxylated support; (2) React the hydroxylated support with a manganese precursor and a cobalt precursor in the presence of a solvent, then perform the second drying and optionally the second calcination.

2. The method according to claim 1, wherein, In step (1), the support is a heat-resistant inorganic oxide and / or a molecular sieve; Preferably, the heat-resistant inorganic oxide is selected from at least one of alumina, silica, titanium oxide, cerium oxide, lanthanum oxide, and zirconium oxide; Preferably, the molecular sieve is selected from at least one of X-type molecular sieve, Y-type molecular sieve, and β-type molecular sieve.

3. The method according to claim 1 or 2, wherein, In step (1), the hydroxylation treatment uses at least one of hydrothermal treatment, ion exchange method, and chemical reactions including alcoholization, etherification, or esterification, preferably hydrothermal treatment; Preferably, in step (1), the hydrothermal treatment includes: performing hydrothermal treatment on the support in the presence of an aqueous medium to obtain a hydroxylated support; Preferably, in step (1), the aqueous medium is provided by water and / or an atmosphere containing water vapor; Preferably, in step (1), the atmosphere containing water vapor further contains at least one of air, methanol, ethanol, and formic acid, and more preferably further contains air; Preferably, in step (1), based on the total volume of the atmosphere containing water vapor, the content of water vapor in the atmosphere containing water vapor is 10-80% by volume, and more preferably 40-80% by volume.

4. The method according to claim 3, wherein, In step (1), the conditions of the hydroxylation treatment include: the temperature is 110-300 °C, the time is 2-12 hours, and the amount of water used is 1-20 mL relative to 1 g of the support; Preferably, in step (1), the conditions for the hydroxylation treatment include: the temperature is 180 - 300 °C, the time is 3 - 8 hours, and the volumetric space velocity of the water vapor-containing atmosphere is 1000 - 3000 h -1 ; Preferably, in step (1), the conditions of the first calcination include: the temperature is 200-550 °C, and the time is 2-4 hours.

5. The method according to claim 1 or 2, wherein, The reaction in step (2) is a redox reaction, and a manganese-cobalt composite oxide is obtained on the surface of the hydroxylated support; Preferably, the morphology of the manganese-cobalt composite oxide is spherical or quasi-spherical particles formed by the cross-stacking of rod-like structures; Preferably, the size of the spherical or quasi-spherical particles is 200 nm - 2 μm; Preferably, the manganese-cobalt composite oxide includes MnCo2O4 and MnO2; Preferably, the surface layer of the rod-like structure is MnO2, and the inside is MnCo2O4; More preferably, the thickness of the MnO2 layer on the surface of the rod-like structure is 1 nm - 3 nm; Preferably, in step (2), based on the metal element, the molar ratio of the manganese precursor to the cobalt precursor is 0.1-2, and more preferably 0.4-0.

8.

6. The method according to claim 1 or 2, wherein, In step (2), the manganese precursor is provided by a manganese-containing compound, preferably provided by potassium permanganate; Preferably, in step (2), the cobalt precursor is provided by a cobalt-containing compound, and more preferably provided by a divalent cobalt salt; Preferably, the reaction in step (2) includes: contacting the hydroxylated support with a solution containing a manganese precursor, and then adding a cobalt precursor to react; Preferably, the concentration of the solution containing the manganese precursor is 0.1-0.3 mol / L; Preferably, in step (2), the hydroxylated support is contacted with the solution containing the manganese precursor by immersing the hydroxylated support in the solution containing the manganese precursor; Preferably, the cobalt precursor is added in the form of a solution containing the cobalt precursor, and the concentration of the solution containing the cobalt precursor is 1-8 times that of the solution containing the manganese precursor.

7. The method according to claim 6, wherein, Step (2) includes heating to the reaction temperature after contacting the hydroxylated support with the solution containing the manganese precursor, and then adding the cobalt precursor for reaction; Preferably, in step (2), the reaction conditions include: temperature of 50-90 °C and time of 1-6 hours; Preferably, in step (2), the conditions for the second calcination include: temperature of 400-550 °C and time of 2-4 hours.

8. The method according to claim 1 or 2, wherein, The method further includes step (3): immersing the second calcined product obtained in step (2) in an impregnating solution containing a noble metal precursor, adjusting the pH to alkaline, preferably adjusting to pH 8-9, standing and then heating, and then performing the third drying and the third calcination to obtain a supported MnCo-based catalyst; Preferably, in step (3), the noble metal is selected from at least one of platinum, palladium, rubidium and rhodium; Preferably, in step (3), the impregnating solution containing the noble metal precursor is provided by a salt solution of the noble metal; Preferably, in step (3), the concentration of the impregnating solution containing the noble metal precursor is 0.1-4 g / L; Preferably, in step (3), the standing conditions include: time of 1-6 hours; Preferably, in step (3), the heating conditions include: temperature of 50-80 °C and time of 1-6 hours; Preferably, in step (3), the conditions for the third calcination include: temperature of 400-500 °C and time of 2-4 hours.

9. The method according to claim 8, wherein, The amounts of the support, the manganese precursor and the cobalt precursor are such that in the second calcined product obtained, based on the total amount of the second calcined product, the content of the hydroxylated support is 85-95 wt%, and the content of the manganese-cobalt composite oxide is 5-15 wt%; Preferably, the amounts of the manganese precursor and the cobalt precursor are such that in the second calcined product obtained, based on the total amount of the second calcined product, the content of part of Mn and Co as MnCo2O4 is 5-14.9 wt%, and the content of the remaining part of Mn as MnO2 is 0.01-0.2 wt%; Preferably, the amount of the impregnating solution containing the noble metal precursor is such that in the supported MnCo-based catalyst obtained, based on the total volume of the supported MnCo-based catalyst, the content of the noble metal by element is 0.1-4 g / L.

10. A supported MnCo-based catalyst prepared by the method according to any one of claims 1-9; preferably, the supported MnCo-based catalyst contains active oxygen; Preferably, based on the total amount of the supported MnCo-based catalyst, the content of the active oxygen is 300-900 μmol / gcat.

11. A method for purifying a hydrogen-containing gas, wherein, The method includes contacting a hydrogen-containing gas with the supported MnCo-based catalyst according to claim 10 for purification; Preferably, the hydrogen-containing gas further contains at least one of helium, carbon monoxide, methane and nitrogen, and more preferably further contains helium; Preferably, based on the total amount of the hydrogen-containing gas, in the hydrogen-containing gas, the concentration of hydrogen is 10-100 ppm; Preferably, the conditions for the contact include: the temperature is 200 - 400 °C, and the volumetric space velocity of the hydrogen-containing gas is 1000 - 6000 h -1 .

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