MnO2 material, preparation method thereof and method for removing sulfide

Abstract

The invention relates to a preparation method of a MnO2 material and a method for removing sulfide in hydrogen. The method comprises the following steps: mixing a manganese source aqueous solution with a graphite oxide filtering stock solution, carrying out hydrothermal crystallization treatment under hydrothermal self-generated pressure and atmosphere, and optionally roasting to obtain the MnO2 material. According to the preparation method, divalent manganese in the graphite oxide filtering stock solution is fully utilized to reduce the preparation cost, the prepared MnO2 material shows excellent performance in the sulfide removal process, sulfide with the mass content of 15% or below in hydrogen can be removed under the mild conditions such as 150 DEG C or below, and the sulfide removal rate is larger than 90%.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen purification, and specifically relates to a MnO2 material and a preparation method thereof, and a method for removing sulfides. Background Art

[0002] Hydrogen sulfide is a toxic, harmful, and undesirable gas. It is a colorless gas that smells like rotten eggs. Usually, hydrogen sulfide poisoning can cause a lot of harm to the body, mainly systemic diseases with damage to the central nervous system, respiratory nervous system, and other multiple organs. If a large amount of hydrogen sulfide is inhaled in a short period of time, it will cause damage to the central nervous system, and clinical symptoms such as dizziness, headache, confusion, and even coma, delirium, and transient syncope will appear. For the respiratory system, pulmonary edema, pneumonia, laryngeal spasm, respiratory paralysis, and severe dyspnea will occur. If a large amount of hydrogen sulfide is inhaled, it will cause respiratory failure and rapid death.

[0003] Hydrogen is an important clean energy source. One of the uses of hydrogen is to supply hydrogen to fuel cells and generate electricity to realize the utilization of hydrogen energy. However, the electrode catalysts of fuel cells are sensitive to sulfides. The presence of trace amounts of sulfides will cause poisoning of the fuel cell electrode catalysts, thereby reducing their efficiency. However, there are few existing methods for treating sulfides in hydrogen, or there are problems such as complex treatment processes and high treatment costs. Summary of the invention

[0004] The purpose of the present invention is to provide a MnO2 material and a preparation method thereof and a method for removing sulfides. The preparation method of the present invention reduces the preparation cost of the MnO2 material by mixing a manganese source with a filtered stock solution of graphite oxide and using the filtered stock solution of graphite oxide as one of the manganese sources. The MnO2 material prepared by the present invention exhibits excellent performance in the process of removing sulfides, 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%.

[0005] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a MnO2 material, the method comprising the following steps:

[0006] (1) mixing a manganese source aqueous solution with a filtered stock solution of graphite oxide to obtain a mixed solution;

[0007] (2) subjecting the mixed solution to hydrothermal crystallization under hydrothermal autogenous pressure and atmosphere, filtering, washing, drying and optionally calcining the obtained material to obtain a crystallized product;

[0008] The molar ratio of the manganese element in the filtered raw solution of graphite oxide to the manganese element in the manganese source aqueous solution is 5.5 or more.

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

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

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

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

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

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

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

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

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

[0018] The third aspect of the present invention provides a method for removing sulfides from hydrogen, the method comprising: contacting the gas containing sulfides with the MnO2 material provided by the second aspect of the present invention at a temperature of 50 to 150°C to carry out a removal reaction.

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

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

[0021] Through the above technical scheme, the present invention mixes a manganese source aqueous solution with a filtered stock solution of graphite oxide, performs a hydrothermal crystallization treatment under hydrothermal autogenous pressure and atmosphere, and optionally roasts to obtain a MnO2 material, using the manganese element in the graphite oxide stock solution as one of the sources of manganese, making full use of the filtered stock solution, and reducing the preparation cost of the MnO2 material. The MnO2 material prepared by the present invention exhibits excellent performance in the process of removing sulfide reaction, and can achieve the removal of 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 invention will be described in detail in the following detailed description. 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 method for preparing a MnO2 material, the method comprising the following steps:

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

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

[0027] The molar ratio of the manganese element in the filtered raw solution of graphite oxide to the manganese element in the manganese source aqueous solution is 5.5 or more.

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

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

[0030] In a specific embodiment of the present invention, the valence state of manganese in the manganese source is 3 or more, preferably one or more of potassium permanganate, potassium manganate, manganese dioxide and manganese heptoxide, more preferably potassium permanganate and potassium manganate.

[0031] In a specific embodiment of the present invention, in the filtered stock solution of graphite oxide, the manganese content in terms of divalent manganese ions is 2 to 30 g / L, preferably 8 to 20 g / L, the potassium content in terms of potassium ions is 1 to 20 g / L, preferably 2 to 15 g / L, the sulfur content in terms of sulfate ions is 10 to 150 g / L, preferably 30 to 100 g / L, and the carbon content in terms of carbon atoms is 0.5 to 10 g / L, preferably 1 to 6 g / L.

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

[0033] In a specific embodiment of the present invention, the graphite oxide filtration stock solution of the present invention is obtained by oxidizing graphite according to the improved Hummer method (without adding sodium nitrate) and then performing solid-liquid separation.

[0034] In a specific embodiment of the present invention, graphite and 98% concentrated sulfuric acid are added to a beaker placed in an ice water bath (<5°C) and stirred to mix evenly, potassium permanganate is slowly added in batches while stirring to mix, and after the addition of potassium permanganate, the mixture is stirred and reacted in a warm water bath at 40°C for 0.5h, and then an appropriate amount of deionized water is added and the temperature of the water bath is raised to 95-98°C for reaction; the beaker is taken out of the water bath and deionized water of about 60°C is added, and stirring is continued to reduce the temperature to below 30°C, and finally an appropriate amount of H2O2 with a mass fraction of 30% is added, and after stirring evenly, the graphite oxide solid is filtered and separated to obtain a graphite oxide filtration stock solution; the dosage ratio of the above reactants is graphite: concentrated sulfuric acid: potassium permanganate: H2O2: water = 1g: 20-50ml: 2-6g: 1-5ml: 100-1000ml.

[0035] In a specific embodiment of the present invention, the conditions of the hydrothermal crystallization treatment include: a temperature of 120 to 200° C. and a time of 1 to 72 hours; preferably, a temperature of 140 to 180° C. and a time of 6 to 48 hours.

[0036] 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; preferably, a temperature of 300-500° C., a time of 2-6 hours, and 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 by the first aspect of the present disclosure.

[0038] In a specific embodiment of the present invention, the XRD spectrum of the MnO2 material has a characteristic peak of δ-MnO2.

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

[0040] In a specific embodiment of the present invention, the MnO2 material is a black powder with an average particle size of less than 0.25 mm, preferably less than 0.1 mm;

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

[0042] The third aspect of the present disclosure provides a method for removing sulfides from hydrogen, the method comprising: contacting a gas containing sulfides with the MnO2 material provided by the second aspect of the present invention at a temperature of 50 to 150° C. to carry out a removal reaction.

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

[0044] The mass content of sulfide in the hydrogen is less than 15%, preferably 5-15%, and the mass content of sulfide in the hydrogen is calculated as hydrogen sulfide.

[0045] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0046] The reagents used in the present invention are all commercially available analytically pure reagents.

[0047] Example 1

[0048] a. Add 50 g of a 20% potassium permanganate aqueous solution and an appropriate amount of a filtered stock solution of graphite oxide in a beaker (the content of manganese in the filtered stock solution of graphite oxide is 11 g / L as divalent manganese ions, 8 g / L as potassium ions, 69 g / L as sulfur ions, and 1.2 g / L as carbon atoms), and mix well. The molar ratio of manganese in the filtered stock solution of graphite oxide to manganese in the potassium permanganate aqueous solution is 7.5.

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

[0050] c. filtering, washing, and drying at 80° C. for 6 h to obtain a solid product;

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

[0052] Example 2

[0053] The preparation method in Example 1 is adopted, except that in step a, the mass ratio of manganese element in the potassium permanganate aqueous solution to manganese element in the graphite oxide filtration stock solution is 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 calcination time was 1 hour.

[0058] Example 5

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

[0060] Example 6

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

[0062] Comparative Example 1

[0063] The preparation method in Example 1 is adopted, except that in step a, an equal amount of water is used to replace the graphite oxide filtration stock solution.

[0064] Comparative Example 2

[0065] The preparation method used in Example 1 is different only in that in step a, the molar ratio of manganese element in the potassium permanganate aqueous solution to manganese element in the filtered stock solution of graphite oxide is 1:1.

[0066] Test Case

[0067] The MnO2 materials of Examples 1 to 6 and Comparative Examples 1 to 2 were tested as follows:

[0068] The average particle size of the prepared product was measured by scanning electron microscopy (ISI-60A electron microscope, ISI Corporation, USA, accelerating voltage 20 kV), and random sampling was performed for particle size statistics.

[0069] The warm nitrogen adsorption and desorption test (BET) was carried out on a JW-BK200C surface area and pore size analyzer of Beijing Jingwei Gaobo Co., Ltd. The specific surface area and pore volume were calculated using the two-parameter BET equation, and the pore distribution was calculated using the BJH method. The sulfide content in hydrogen before and after removal was analyzed by online chromatography (Nexis-2030, Shimadzu, Japan) and SCD fluorescence detector (SCD-2030).

[0070] 500 mg of the examples and comparative examples prepared by the present invention were loaded as catalysts into the constant temperature section of the reactor of a fixed bed micro reactor with an inner diameter of 12 mm and a length of 500 mm after passivation, and quartz sand was filled up and down. The hydrogen sulfide content in the hydrogen raw material standard gas is 14.2% by weight, and it is passed into the desulfurization reaction at a flow rate of 30 ml / min at 110°C and 2.1 MPa. The hydrogen sulfide content in the hydrogen after the desulfurization reaction is analyzed online, and the sulfide removal rate is calculated. The test results of the sulfide removal rate at 1.5h are shown in Table 1, and other characterization results of the prepared product are shown in Table 2.

[0071] Table 1

[0072] Sulfide 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 of Table 1 and Table 2, it can be seen that the MnO2 material prepared by the preparation method provided by the present invention shows excellent performance in the desulfurization reaction process compared with the comparative example, and can remove sulfides with a mass content of less than 15% in hydrogen under mild conditions, with a sulfide removal rate of more than 90%, and fully utilizes the manganese element in the graphite oxide filtration stock solution to reduce the preparation cost of the MnO2 material.

[0076] It can be seen from the test results of Examples 1 to 6 that when the molar ratio of the manganese element in the filtered stock solution of graphite oxide to the manganese element in the manganese source aqueous solution, the element content in the filtered stock solution of graphite oxide, the conditions of the hydrothermal crystallization treatment, and the calcination conditions are within the specified range of the present invention, the effect and performance of the product prepared by the present invention can be further improved.

[0077] From the test results of Comparative Examples 1 to 2, it can be seen that in Comparative Example 1, an equal amount of water is used to replace the graphite oxide filtration stock solution, and no solid substance can be obtained by solid-liquid separation after hydrothermal crystallization treatment, resulting in a low sulfide removal rate in hydrogen; since the molar ratio of the manganese element in the potassium permanganate aqueous solution and the manganese element in the graphite oxide filtration stock solution in Comparative Example 2 is 1:1, the manganese element content provided by the graphite oxide filtration stock solution is relatively low, resulting in the prepared MnO2 material having a significantly lower sulfide removal rate in hydrogen than that in Example 1.

[0078] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0079] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0080] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a MnO2 material, wherein: The method comprises the following steps: (1) mixing a manganese source aqueous solution with a filtered stock solution of graphite oxide to obtain a mixed solution; (2) subjecting the mixed solution to hydrothermal crystallization under hydrothermal autogenous pressure and atmosphere, filtering, washing, drying and optionally calcining the obtained material to obtain a crystallized product; The molar ratio of the manganese element in the filtered raw solution of graphite oxide to the manganese element in the manganese source aqueous solution is 5.5 or more.

2. The method according to claim 1, wherein: The molar ratio of the manganese element in the manganese source aqueous solution to the manganese element in the filtered stock solution of graphite oxide is 1:(5.5-20), preferably 1:(8-15).

3. The method according to claim 1, wherein: The valence state of manganese in the manganese source is trivalent or higher, and is preferably one or more of potassium permanganate, potassium manganate, manganese dioxide and manganese heptoxide.

4. The method according to claim 1, wherein: In the filtered stock solution of the graphite oxide, the manganese content calculated as divalent manganese ions is 2-30 g / L, the potassium content calculated as potassium ions is 1-20 g / L, the sulfur content calculated as sulfate ions is 10-150 g / L, and the carbon content calculated as carbon atoms is 0.5-10 g / L.

5. The method according to claim 1, wherein: The conditions of the hydrothermal crystallization treatment include: a temperature of 120 to 200° C. under autogenous pressure for 1 to 72 hours; preferably, a temperature of 140 to 180° C. for 6 to 48 hours; 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; preferably, a temperature of 300-500° C., a time of 2-6 hours, and a pressure of 0.1-0.2 MPa.

6. MnO2 material prepared by the method described in any one of claims 1 to 5.

7. The MnO2 material according to claim 6, wherein The XRD spectrum of the MnO2 material has a characteristic peak of δ-MnO2.

8. The MnO2 material according to claim 7, wherein The MnO2 material is a black powder with an average particle size of less than 0.25 mm; The specific surface area of ​​the MnO2 material is 40 to 150 m 2 / g, pore volume is 0.3-0.8 ml / g; preferably, specific surface area is 60-100 m 2 / g, and the pore volume is 0.4~0.6ml / g.

9. A method for removing sulfide from hydrogen, the method comprising: At a temperature of 50 to 150° C., a gas containing sulfides is brought into contact with a MnO2 material as described in any one of claims 6 to 8 to carry out a removal reaction.

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

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