MnO2 material, preparation method thereof and method for removing sulfides

Abstract

The present disclosure relates to a preparation method of MnO2 material and a method for removing sulfides from hydrogen, which comprises: mixing a manganese source aqueous solution with a filtered stock solution of graphite oxide, and then performing hydrothermal crystallization treatment under hydrothermal autogenous pressure and atmosphere, and optionally performing calcination to obtain the MnO2 material. The preparation method fully utilizes the divalent manganese in the filtered stock solution of graphite oxide to reduce the preparation cost. The MnO2 material prepared by the method exhibits excellent performance in the process of removing sulfides, and can remove sulfides with a mass content of less than 15% from hydrogen under mild conditions, such as below 150 DEG C, and the removal rate of sulfides is greater than 90%.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the field of hydrogen purification, and particularly relates to a MnO2 material, a preparation method thereof and a method for removing sulfides. BACKGROUND

[0002] Hydrogen sulfide is a toxic, harmful and undesirable gas, which is a gas with a rotten egg smell but no color. Generally, hydrogen sulfide poisoning can cause many hazards to the body, mainly the central nervous system, respiratory nervous system and other multiple organ damage to the whole body system. If a large amount of hydrogen sulfide is inhaled in a short time, the central nervous system will be damaged, at which time dizziness, headache, blurred consciousness, and even coma, delirium, and transient syncope will occur. For the respiratory system, pulmonary edema, pneumonia, laryngeal spasm, respiratory paralysis, and severe dyspnea will occur, and if a large amount of hydrogen sulfide is inhaled, respiratory failure will occur and death will occur rapidly.

[0003] Hydrogen is an important clean energy. One of the uses of hydrogen is to supply hydrogen to fuel cells to generate electricity to realize the utilization of hydrogen energy. However, the electrode catalyst of the fuel cell is sensitive to sulfides, and the presence of trace sulfides will cause poisoning of the electrode catalyst of the fuel cell, thereby reducing its efficiency. However, there are few existing methods for treating sulfides in hydrogen, or there are problems such as complex treatment process and high treatment cost. SUMMARY

[0004] The purpose of the present application is to provide a MnO2 material, a preparation method thereof and a method for removing sulfides. The preparation method of the present application reduces the preparation cost of the MnO2 material by mixing a manganese source with an oxidized graphite filtrate stock solution, using the oxidized graphite filtrate stock solution as one of the manganese sources. The MnO2 material prepared by the present application exhibits excellent performance in the process of removing sulfides, and can remove sulfides with a mass content of 15% or less in hydrogen under mild conditions, with a sulfide removal rate of greater than 90%.

[0005] To achieve the above purpose, the first aspect of the present application provides a preparation method of a MnO2 material, which comprises the following steps:

[0006] (1) mixing a manganese source aqueous solution with an oxidized graphite filtrate stock solution to obtain a mixed solution;

[0007] (2) under hydrothermal autogenous pressure and atmosphere, hydrothermal crystallization treatment is performed on the mixed solution, and the obtained material is filtered, washed, dried and optionally calcined to obtain a crystallization product;

[0008] The molar ratio of manganese elements in the oxidized graphite filtrate stock solution to manganese elements in the manganese source aqueous solution is greater than 5.5.

[0009] Optionally, the molar ratio of manganese element in the manganese source aqueous solution to manganese element in the filtered stock solution of the oxidized graphite is 1:(5.5-20).

[0010] Optionally, the valence of manganese in the manganese source is 3 or more, preferably one or more of potassium permanganate, potassium manganate, manganese dioxide and dimanganese heptoxide.

[0011] Optionally, in the filtered stock solution of the oxidized graphite, the content of manganese element calculated as divalent manganese ions is 2-30 g / L, the content of potassium element calculated as potassium ions is 1-20 g / L, the content of sulfur element calculated as sulfate ions is 10-150 g / L, and the content of carbon element calculated as carbon atoms is 0.5-10 g / L.

[0012] Optionally, the conditions of the hydrothermal crystallization treatment include a temperature of 120-200°C and a time of 1-72 hours.

[0013] The calcination conditions include a temperature of 200-600°C, a time of 1-12 hours, and a pressure of 0.1-0.5 MPa.

[0014] The second aspect of the present application provides a MnO2 material prepared by the method provided in the first aspect of the present application.

[0015] Optionally, the XRD spectrum of the MnO2 material has the characteristic peaks of δ-MnO2.

[0016] Optionally, the MnO2 material is a black powder with an average particle size of 0.25 mm or less.

[0017] The specific surface area of the MnO2 material is 40-150 m2 / g, and the pore volume is 0.3-0.8 ml / g. 2

[0018] The third aspect of the present application provides a method for removing sulfides from hydrogen, which comprises: contacting a gas containing sulfides with the MnO2 material provided in the second aspect of the present application at a temperature of 50-150°C to perform a removal reaction.

[0019] Optionally, the reaction conditions of the method for removing sulfides from hydrogen include a temperature of 50-150°C, a pressure of 0.1-5.0 MPa, and a space velocity of 100-100000 h-1. -1

[0020] The mass content of sulfides in the hydrogen is 15% or less, and the content of sulfides in the hydrogen is calculated as hydrogen sulfide.

[0021] ​​By the technical scheme, the MnO2 material is prepared by mixing the manganese source aqueous solution and the filtered stock solution of the oxidized graphite, and performing hydrothermal crystallization treatment under hydrothermal autogenic pressure and atmosphere, and optionally calcining, the manganese element in the stock solution of the oxidized graphite is used as one of the manganese sources, the filtered stock solution of the oxidized graphite is fully utilized, and the preparation cost of the MnO2 material is reduced. The MnO2 material prepared by the method has excellent performance in a sulfide removal reaction process, and can remove sulfides with a mass content of less than 15% in hydrogen under mild conditions, and the sulfide removal rate is greater than 90%.

[0022] Other features and advantages of the present application will be described in detail in the following specific embodiments. DETAILED DESCRIPTION

[0023] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0024] The first aspect of the present disclosure provides a preparation method of a MnO2 material, the method comprising the following steps:

[0025] (1) mixing a manganese source aqueous solution and a filtered stock solution of oxidized graphite to obtain a mixed solution;

[0026] (2) performing hydrothermal crystallization treatment on the mixed solution under hydrothermal autogenic pressure and atmosphere, and filtering, washing, drying and optionally calcining the obtained material to obtain a crystallization product;

[0027] The molar ratio of the manganese element in the filtered stock solution of the oxidized graphite to the manganese element in the manganese source aqueous solution is greater than 5.5.

[0028] The preparation method of the present application mixes the manganese source aqueous solution and the filtered stock solution of the oxidized graphite, uses the manganese element in the stock solution of the oxidized graphite as one of the manganese sources, mixes with the manganese source, fully utilizes the filtered stock solution of the oxidized graphite, and reduces the preparation cost of the MnO2 material.

[0029] In one specific embodiment of the present application, the molar ratio of the manganese element in the manganese source aqueous solution to the manganese element in the filtered stock solution of the oxidized graphite is 1:(5.5-20), and preferably 1:(8-15).

[0030] In one specific embodiment of the present application, the valence of manganese in the manganese source is greater than 3, and is preferably one or more of potassium permanganate, potassium manganate, manganese dioxide and dimanganese heptoxide, and more preferably potassium permanganate and potassium manganate.

[0031] In one embodiment of the present application, the content of manganese element calculated as divalent manganese ions in the graphite oxide filtration stock solution is 2-30 g / L, preferably 8-20 g / L, the content of potassium element calculated as potassium ions is 1-20 g / L, preferably 2-15 g / L, the content of sulfur element calculated as sulfate ions is 10-150 g / L, preferably 30-100 g / L, and the content of carbon element calculated as carbon atoms is 0.5-10 g / L, preferably 1-6 g / L.

[0032] In a further preferred embodiment, the graphite oxide filtration stock solution is an aqueous solution mainly containing manganese, potassium, sulfur, carbon and other elements, wherein the content of manganese element calculated as divalent manganese ions is 11 g / L, the content of potassium element calculated as potassium ions is 8 g / L, the content of sulfur element calculated as sulfate ions is 69 g / L, and the content of carbon element calculated as carbon atoms is 1.2 g / L (the carbon element mainly comes from the residual soluble graphite oxide in the stock solution).

[0033] In one embodiment of the present application, the graphite oxide filtration stock solution of the present application is obtained by solid-liquid separation after oxidizing graphite according to the improved Hummer method (without adding sodium nitrate).

[0034] In one embodiment of the present application, the graphite and 98% concentrated sulfuric acid are added into a beaker placed in an ice water bath (<5℃) and stirred to mix uniformly, and then potassium permanganate is added in batches under stirring, and after the addition of potassium permanganate, the reaction is continued under stirring at 40℃ for 0.5 h, then deionized water is added, the temperature of the water bath is increased to 95-98℃, and the reaction is carried out; the beaker is taken out of the water bath and deionized water at about 60℃ is added, and the temperature is continuously reduced to below 30℃ under stirring, then an appropriate amount of 30% H2O2 is added, and after stirring uniformly, the graphite oxide solid is separated by filtration to obtain the graphite oxide filtration stock solution; the amount ratio of the above-mentioned reactants is graphite: concentrated sulfuric acid: potassium permanganate: H2O2: water = 1 g: 20-50 ml: 2-6 g: 1-5 ml: 100-1000 ml.

[0035] In one embodiment of the present application, the hydrothermal crystallization treatment is carried out at a temperature of 120-200℃ for 1-72 hours, preferably at a temperature of 140-180℃ for 6-48 hours.

[0036] The calcination is carried out at a temperature of 200-600℃ for 1-12 hours, preferably at a temperature of 300-500℃ for 2-6 hours, and at a pressure of 0.1-0.5 MPa, preferably at a pressure of 0.1-0.2 MPa.

[0037] The second aspect of the present disclosure provides a MnO2 material prepared by the method provided in the first aspect of the present disclosure.

[0038] In one specific embodiment of the present disclosure, the XRD spectrum of the MnO2 material has the characteristic peaks of δ-MnO2.

[0039] It should be noted that the crystal form of the MnO2 material prepared by the present disclosure is δ-MnO2. δ-MnO2 belongs to a typical monoclinic system and has a large interlayer spacing, and exhibits excellent performance in the removal of sulfides, so that sulfides with a mass content of less than or equal to 15% in hydrogen can be removed under mild conditions, and the removal rate of sulfides is greater than 90%.

[0040] In one specific embodiment of the present disclosure, the MnO2 material is a black powder with an average particle size of 0.25 mm or less, preferably 0.1 mm or less.

[0041] The specific surface area of the MnO2 material is 40-150 m 2 / g, and the pore volume is 0.3-0.8 ml / g; preferably, the specific surface area is 60-100 m 2 / g, and the pore volume is 0.4-0.6 ml / g.

[0042] The third aspect of the present disclosure provides a method for removing sulfides from hydrogen, which comprises: contacting a gas containing sulfides with the MnO2 material provided in the second aspect of the present disclosure at a temperature of 50-150°C to perform a removal reaction.

[0043] In one specific embodiment of the present disclosure, the reaction conditions of the method for removing sulfides from hydrogen include: a temperature of 50-150°C, a pressure of 0.1-5.0 MPa, and a space velocity of 100-100000 h -1 ; preferably, the temperature is 60-120°C, the pressure is 0.5-3.0 MPa, and the space velocity is 500-50000 h -1 .

[0044] The mass content of sulfides in the hydrogen is 15% or less, preferably 5-15%, and the content of sulfides in the hydrogen is calculated based on hydrogen sulfide.

[0045] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited in any way by the examples.

[0046] The reagents used in the present disclosure are all commercially available analytical pure reagents.

[0047] Example 1

[0048] a 50 g of a 20% mass concentration potassium permanganate aqueous solution and an appropriate amount of a filtered stock solution of graphite oxide (the filtered stock solution of graphite oxide contains 11 g / L of manganese element calculated as divalent manganese ions, 8 g / L of potassium element calculated as potassium ions, 69 g / L of sulfur element calculated as sulfate ions, and 1.2 g / L of carbon element calculated as carbon atoms) were mixed in a beaker, wherein the molar ratio of manganese element in the filtered stock solution of graphite oxide to manganese element in the potassium permanganate aqueous solution was 7.5;

[0049] b the mixture was subjected to hydrothermal crystallization treatment at 140°C under autogenous pressure for 24 h;

[0050] c the material after the hydrothermal crystallization treatment was filtered, washed, and dried at 80°C for 6 h to obtain a solid product;

[0051] d the dried solid product was calcined at a calcination temperature of 300°C for 4 h to obtain a crystallized product δ-MnO2.

[0052] Example 2

[0053] The preparation method in Example 1 was adopted, except that in step a, the mass ratio of manganese element in the potassium permanganate aqueous solution to manganese element in the filtered stock solution of graphite oxide was 1:10.

[0054] Example 3

[0055] The preparation method in Example 1 was adopted, except that in step b, the hydrothermal crystallization temperature was 100°C.

[0056] Example 4

[0057] The preparation method in Example 1 was adopted, except that in step d, the calcination temperature was 800°C and the time was 1 h.

[0058] Example 5

[0059] The preparation method in Example 1 was adopted, except that in step d, no calcination was performed.

[0060] Example 6

[0061] The preparation method in Example 1 was adopted, except that in step a, the filtered stock solution of graphite oxide used contained 22 g / L of manganese element calculated as divalent manganese ions, 17 g / L of potassium element calculated as potassium ions, 25 g / L of sulfur element calculated as sulfate ions, and 0.9 g / L of carbon element calculated as carbon atoms, and the molar ratio of manganese element in the filtered stock solution of graphite oxide to manganese element in the potassium permanganate aqueous solution was consistent with that in Example 1.

[0062] Comparative Example 1

[0063] The preparation method in Example 1 is adopted, with the only difference being that in step a, the filtrate of the graphite oxide is replaced with an equal amount of water.

[0064] Comparative Example 2

[0065] The preparation method in Example 1 is adopted, with the only difference being that in step a, the molar ratio of manganese in the aqueous potassium permanganate solution to manganese in the filtrate of the graphite oxide is 1:1.

[0066] Test Example

[0067] The MnO2 materials in Examples 1-6 and Comparative Examples 1-2 are tested as follows:

[0068] The average particle size of the prepared product is determined by a scanning electron microscope (ISI-60A electron microscope, ISI Corporation, USA, acceleration voltage 20 kV), and the particle size is statistically counted by random sampling.

[0069] The nitrogen adsorption-desorption test (BET) is performed on a JW-BK200C specific surface area and pore size analyzer, Beijing Jeol Highborn Co., Ltd. The specific surface area and pore volume are calculated by the two-parameter BET equation, and the pore distribution is calculated by the BJH method. The sulfide content in hydrogen before and after removal is analyzed by an online chromatograph (Nexis-2030, Shimadzu Corporation, Japan) and an SCD fluorescence detector (SCD-2030).

[0070] 500 mg of the prepared examples and comparative examples are loaded into the reactor constant temperature section of a passivated fixed bed microreactor with an inner diameter of 12 mm and a length of 500 mm as catalysts, and quartz sand is filled in the upper and lower parts. Hydrogen raw gas with a hydrogen sulfide content of 14.2 wt% is introduced into the sulfide removal reaction at a flow rate of 30 ml / min at 110°C and 2.1 MPa, and the hydrogen sulfide content in the hydrogen after the removal reaction is analyzed online, and the sulfide removal rate is calculated. The test results of the sulfide removal rate at 1.5 h are shown in Table 1, and the other characterization results of the prepared products are shown in Table 2.

[0071] Table 1

[0072] Sulphide removal rate / % Example 1 96 Example 2 85 Example 3 92 Example 4 91 Example 5 83 Example 6 80 Comparative Example 1 6 Comparative Example 2 49

[0073] Table 2

[0074]

[0075] According to the test results in Table 1 and Table 2, the MnO2 material prepared by the preparation method provided by the application has excellent performance in the removal of sulfides in the reaction process, can remove sulfides with a mass content of less than 15% in hydrogen under mild conditions, and has a sulfide removal rate of more than 90%, and fully utilizes the manganese element in the graphite oxide filtrate to reduce the preparation cost of the MnO2 material.

[0076] According to the test results of Examples 1-6, when the molar ratio of manganese elements in the graphite oxide filtrate to the manganese elements in the manganese source aqueous solution, the element content in the graphite oxide filtrate, the hydrothermal crystallization treatment conditions, and the calcination conditions are within the range defined by the application, the effect and performance of the product prepared by the application can be further improved.

[0077] According to the test results of Comparative Examples 1-2, in Comparative Example 1, an equal amount of water is used to replace the graphite oxide filtrate, and after hydrothermal crystallization treatment, solid-liquid separation cannot obtain solid material, resulting in low removal rate of sulfides in hydrogen; and in Comparative Example 2, the molar ratio of manganese elements in the potassium permanganate aqueous solution to the manganese elements in the graphite oxide filtrate is 1:1, and the manganese element content provided by the graphite oxide filtrate is low, resulting in that the removal rate of sulfides in hydrogen by the prepared MnO2 material is significantly lower than that of Example 1.

[0078] The above describes the preferred embodiments of the application, but the application is not limited to the specific details in the above embodiments, and various simple modifications can be made to the technical solutions of the application within the technical concept of the application, and these simple modifications all belong to the protection scope of the application.

[0079] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the application will not further describe various possible combinations.

[0080] In addition, various different embodiments of the application can also be combined in any appropriate manner, as long as they do not deviate from the idea of the application, and they should also be considered as disclosed by the application.

Claims

1. A MnO2 material, characterized in that, The XRD spectrum of the MnO2 material has characteristic peaks of δ-MnO2; The average particle size of the MnO2 material is less than or equal to 0.25 mm; The specific surface area of the MnO2 material is 40-150 m 2 / g, and the pore volume is 0.3-0.8 ml / g; The preparation method of the MnO2 material comprises the following steps: (1) mixing a manganese source aqueous solution and a filtered stock solution of oxidized graphite to obtain a mixed solution; (2) performing hydrothermal crystallization treatment on the mixed solution under hydrothermal autogenous pressure and atmosphere, and then filtering, washing, drying and optionally calcining the obtained material to obtain a crystallization product; The molar ratio of manganese in the filtered stock solution of oxidized graphite to manganese in the manganese source aqueous solution is greater than or equal to 5.5; The valence of manganese in the manganese source aqueous solution is greater than or equal to 3; The hydrothermal crystallization treatment is performed at a temperature of 120-200°C under autogenous pressure for 1-72 hours. The filtered stock solution of oxidized graphite is obtained by solid-liquid separation after preparing oxidized graphite according to an improved Hummer method.

2. The Mn02 material of claim 1, wherein, The molar ratio of manganese in the manganese source aqueous solution to manganese in the filtered stock solution of oxidized graphite is 1:(5.5-20).

3. The Mn02 material of claim 2, wherein, The molar ratio of manganese in the manganese source aqueous solution to manganese in the filtered stock solution of oxidized graphite is 1:(8-15).

4. The Mn02 material of claim 1, wherein, The manganese source is one or more of potassium permanganate, potassium manganate, manganese dioxide and dimanganese heptoxide.

5. The Mn02 material of claim 1, wherein, In the filtered stock solution of oxidized graphite, the content of manganese calculated as divalent manganese ions is 2-30 g / L, the content of potassium calculated as potassium ions is 1-20 g / L, the content of sulfur calculated as sulfate ions is 10-150 g / L, and the content of carbon calculated as carbon atoms is 0.5-10 g / L.

6. The Mn02 material of claim 1, wherein, The hydrothermal crystallization treatment is performed at a temperature of 140-180°C under autogenous pressure for 6-48 hours. The calcination is performed at a temperature of 200-600°C for 1-12 hours under a pressure of 0.1-0.5 MPa.

7. The Mn02 material of claim 6, wherein, The calcination is performed at a temperature of 300-500°C for 2-6 hours under a pressure of 0.1-0.2 MPa.

8. The Mn02 material of claim 1, wherein, The specific surface area of the MnO2 material is 60-100 m 2 / g, and the pore volume is 0.4-0.6 ml / g.

9. A method for removing sulfides from hydrogen gas, the method comprising: The sulfide-containing gas is contacted with the MnO2 material of any one of claims 1-8 at a temperature of 50-150°C to perform a removal reaction.

10. The method of claim 9, wherein, The reaction conditions of the method for removing sulfides in hydrogen include a temperature of 50-150℃, a pressure of 0.1-5.0 MPa, and a space velocity of 100-100000 h -1 ; The mass content of sulfides in the hydrogen is less than or equal to 15%, and the content of sulfides in the hydrogen is calculated as hydrogen sulfide.

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