Manganese oxide material, preparation method thereof and hydrogen purification method
Through the preparation of manganese oxide materials and hydrogen purification methods, the problem of removing sulfide impurities in hydrogen is solved, and efficient purification and cost reduction of hydrogen for fuel cells is achieved.
Patent Information
- Application Number
- CN202310752005.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-25
- Publication Date
- 2024-12-27
AI Technical Summary
The prior art is difficult to effectively remove sulfide impurities in hydrogen gas with a temperature above 100°C, affecting the quality of hydrogen used in fuel cells.
By using the preparation method of manganese oxide material, a manganese source is mixed with a filter stock solution of graphite oxide, and hydrothermal treatment is carried out under hydrothermal self-generating pressure and atmosphere to obtain a manganese oxide material, and hydrogen is made under 60-180°C. The material was contacted for purification.
High-efficiency purification of hydrogen under mild conditions is achieved, the sulfide content in hydrogen is reduced, the impurity content requirements of hydrogen for fuel cells is met, and the preparation cost of manganese oxide materials is reduced.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of hydrogen purification, and specifically relates to a manganese oxide material and a preparation method thereof, and a method for purifying hydrogen. Background Art
[0002] Hydrogen is an important clean energy source. The main sources of hydrogen are hydrogen produced from fossil resources and industrial by-product hydrogen. Hydrogen produced from fossil resources includes hydrogen produced from coal and natural gas, and industrial by-product hydrogen includes hydrogen produced from the dehydrogenation of ethylbenzene to produce styrene, and hydrogen produced from the dehydrogenation of propane to produce propylene. At present, 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 electrode catalysts of fuel cells, thereby reducing their efficiency. Therefore, strict requirements are placed on the sulfide content of hydrogen used in fuel cells. The international requirement is that the sulfide content calculated as hydrogen sulfide should be less than 4ppb, which is the most stringent requirement for the impurity content in hydrogen used in fuel cells. How to ensure that the sulfide content of hydrogen used in fuel cells is qualified is the technical key to hydrogen used in fuel cells. Hydrogen production from fossil resources and industrial by-product hydrogen are currently one of the important sources of hydrogen, but the initial temperature of by-product hydrogen from these sources is generally greater than 100°C after being separated from the reaction system. How to remove sulfide impurities in hydrogen with a temperature above 100°C is one of the problems currently faced by hydrogen production from fossil resources and industrial by-product hydrogen for use in fuel cells. Summary of the invention
[0003] The purpose of the present invention is to provide a manganese oxide material and a preparation method thereof and a method for purifying hydrogen. The preparation method of the present invention reduces the preparation cost 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 manganese oxide prepared by the present invention exhibits excellent performance in the hydrogen purification reaction process, and the sulfide content in the purified hydrogen can meet the requirements for the sulfide impurity content in hydrogen used in fuel cells.
[0004] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a manganese oxide material, the method comprising:
[0005] (1) mixing a manganese source with a filtered stock solution of graphite oxide and optionally water to obtain a mixed solution, wherein the molar ratio of manganese element in the manganese source to manganese element in the filtered stock solution of graphite oxide is 3 or more;
[0006] (2) The mixed solution is subjected to hydrothermal treatment under hydrothermal autogenous pressure and atmosphere, and the obtained material is filtered, washed, dried and optionally calcined to obtain the manganese oxide material.
[0007] Optionally, the molar ratio of the manganese element in the manganese source to the manganese element in the filtered stock solution of graphite oxide is 3-5.
[0008] 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.
[0009] Optionally, based on the manganese element in the filtered stock solution of the graphite oxide, the amount of the manganese source is 2 to 60 mol parts, preferably 5 to 30 mol parts, and the amount of water is 0 to 500 mol parts, preferably 0 to 200 mol parts, relative to 100 mol parts of the filtered stock solution of the graphite oxide.
[0010] Optionally, the filtered stock solution of graphite oxide is obtained by preparing graphite oxide according to an improved Hummer method and then performing solid-liquid separation;
[0011] No nitrate is added during the reaction of the improved Hummer method;
[0012] 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 1.5-25 g / L, the sulfur content calculated as sulfate ions is 20-200 g / L, and the carbon content calculated as carbon atoms is 0.2-10 g / L.
[0013] Optionally, the conditions of the hydrothermal treatment include: a temperature of 80 to 180° C. and a time of 1 to 72 hours; preferably, a temperature of 100 to 140° C. and a time of 2 to 24 hours;
[0014] The calcination conditions include: a temperature of 200 to 800° C., a time of 1 to 12 hours, and a pressure of 0.1 to 0.5 MPa.
[0015] The second aspect of the present invention provides a manganese oxide material prepared by the method provided by the first aspect of the present invention.
[0016] Optionally, the manganese oxide material has a characteristic peak of β-MnO2 in the XRD spectrum; wherein the Mn element content in the manganese oxide material is 25 to 50 weight %, preferably 30 to 45 weight %; the S element content is 0.5 to 12 weight %, preferably 1 to 8 weight %; and the K element content is 1 to 15 weight %, preferably 2 to 10 weight %.
[0017] Optionally, the manganese oxide material is black needle-shaped powder particles, and the average length of the needle-shaped powder particles is less than 0.5 mm;
[0018] The specific surface area of the manganese oxide material is 5 to 100 m 2 / g, pore volume is 0.02-0.2 ml / g; preferably, specific surface area is 15-50 m 2 / g, and the pore volume is 0.05~0.1ml / g.
[0019] The third aspect of the present invention provides a method for purifying hydrogen, the method comprising: contacting hydrogen with the manganese oxide material provided by the second aspect of the present invention at a temperature of 60 to 180° C. to perform a purification reaction;
[0020] Optionally, the reaction conditions of the hydrogen purification method include: temperature of 60-180°C, pressure of 0.1-5.0 MPa, and space velocity of 10-5000 h -1 ;
[0021] The mass content of sulfide in the hydrogen is less than 1000 ppm, and the sulfide content in the hydrogen is calculated as hydrogen sulfide.
[0022] Through the above technical scheme, the present invention obtains a manganese oxide material by mixing a manganese source with a filtered stock solution of graphite oxide and optional water, performing a hydrothermal treatment under a hydrothermal autogenous pressure and atmosphere, and optionally calcining the filtered stock solution of graphite oxide as one of the manganese sources, thereby reducing the preparation cost. The manganese oxide material prepared by the present invention exhibits excellent performance in the hydrogen purification reaction process, and the sulfide content in the purified hydrogen can meet the requirements for the sulfide impurity content in hydrogen used in fuel cells.
[0023] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION
[0024] 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.
[0025] A first aspect of the present disclosure provides a method for preparing a manganese oxide material, the method comprising:
[0026] (1) mixing a manganese source with a filtered stock solution of graphite oxide and optionally water to obtain a mixed solution, wherein the molar ratio of manganese element in the manganese source to manganese element in the filtered stock solution of graphite oxide is 3 or more;
[0027] (2) subjecting the mixed solution to hydrothermal treatment under hydrothermal autogenous pressure and atmosphere, filtering, washing, drying and optionally calcining the obtained material to obtain the manganese oxide material.
[0028] The preparation method of the present invention mixes the manganese source with the filtered stock solution of graphite oxide, uses divalent manganese and high-valent manganese in the graphite oxide stock solution as one of the manganese sources and mixes it with the manganese source, thereby fully utilizing the filtered stock solution of graphite oxide and reducing the preparation cost.
[0029] In a specific embodiment of the present invention, the molar ratio of the manganese element in the manganese source to the manganese element in the filtered stock solution of graphite oxide is preferably 3-5, and more preferably 3-4.
[0030] In a specific embodiment of the present invention, the valence state of manganese in the manganese source is trivalent or higher, and specifically can be one or more of potassium permanganate, potassium manganate, manganese dioxide and manganese heptoxide, preferably potassium permanganate.
[0031] In a specific embodiment of the present invention, based on the manganese element in the filtered graphite oxide solution, the amount of the manganese source is 2 to 60 molar parts, preferably 5 to 30 molar parts, and the amount of water is 0 to 500 molar parts, preferably 0 to 200 molar parts, relative to 100 molar parts of the filtered graphite oxide solution.
[0032] In a specific embodiment of the present invention, the filtered stock solution of graphite oxide is obtained by preparing graphite oxide according to an improved Hummer method and then performing solid-liquid separation;
[0033] No nitrate is added during the reaction of the modified Hummer method.
[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: 3-6g: 0.1-2ml: 50-1000ml.
[0035] In a specific embodiment of the present invention, in the filtered stock solution of graphite oxide, the manganese content calculated as divalent manganese ions is 2 to 30 g / L, preferably 5 to 20 g / L, the potassium content calculated as potassium ions is 1.5 to 25 g / L, preferably 4.5 to 18 g / L, the sulfur content calculated as sulfate ions is 20 to 200 g / L, preferably 50 to 100 g / L, and the carbon content calculated as carbon atoms is 0.2 to 10 g / L, preferably 1.0 to 6 g / L.
[0036] 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 19 g / L, the potassium content calculated as potassium ions is 13 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; wherein the main source of the carbon element is the soluble graphite oxide remaining in the stock solution.
[0037] In a specific embodiment of the present invention, the conditions of the hydrothermal treatment include: a temperature of 80 to 180° C. and a time of 1 to 72 hours; preferably, a temperature of 100 to 140° C. and a time of 2 to 24 hours;
[0038] The calcination conditions include: temperature of 200-800° C., time of 1-12 hours, and pressure of 0.1-0.5 MPa; preferably, temperature of 300-500° C., time of 2-6 hours, and pressure of 0.1-0.2 MPa.
[0039] A second aspect of the present disclosure provides a manganese oxide material prepared by the method provided by the first aspect of the present disclosure.
[0040] In a specific embodiment of the present invention, the XRD spectrum of the manganese oxide material has a characteristic peak of β-MnO2; wherein, based on the mass of the manganese oxide material, the Mn element content in the manganese oxide material is 25-50 weight %, preferably 30-45 weight %; the S element content is 0.5-12 weight %, preferably 1-8 weight %; the K element content is 1-15 weight %, preferably 2-10 weight %; and the remainder is mainly O element.
[0041] It should be noted that the crystal form of the manganese oxide material prepared by the present invention is mainly β-MnO2. The β-MnO2 manganese oxide material obtained by the present invention exhibits excellent performance in the hydrogen purification reaction process, and can achieve hydrogen purification under mild conditions. The sulfide content in the purified hydrogen can meet the requirements for the sulfide impurity content in hydrogen used in fuel cells.
[0042] In a specific embodiment of the present invention, the manganese oxide material is black needle-shaped powder particles, and the average length of the needle-shaped powder particles is less than 0.5 mm, preferably less than 0.2 mm;
[0043] The specific surface area of the manganese oxide material is 5 to 100 m 2 / g, pore volume is 0.02-0.2 ml / g; preferably, specific surface area is 15-50 m 2 / g, and the pore volume is 0.05~0.1ml / g.
[0044] The third aspect of the present disclosure provides a method for purifying hydrogen, the method comprising: contacting hydrogen with the manganese oxide material provided by the second aspect of the present disclosure at a temperature of 60 to 180° C. to perform a purification reaction;
[0045] In a specific embodiment of the present invention, the reaction conditions of the hydrogen purification method include: temperature of 60-180°C, pressure of 0.1-5.0 MPa, and space velocity of 10-5000 h -1 Preferably, the temperature is 80-160°C, the pressure is 0.5-3MPa, and the air velocity is 50-2000h -1 .
[0046] The mass content of sulfide in the hydrogen is less than 1000 ppm, and the content of sulfide in the hydrogen is calculated as hydrogen sulfide.
[0047] In the present invention, the hydrogen purification method is carried out under relatively medium temperature, medium concentration and low space velocity conditions to achieve purification of hydrogen under mild conditions. The sulfide content in the purified hydrogen can meet the requirements for the sulfide impurity content in hydrogen used in fuel cells.
[0048] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.
[0049] The reagents used in the present invention are all commercially available analytically pure reagents.
[0050] Example 1
[0051] a. Add 5 g of potassium permanganate and an appropriate amount of graphite oxide filtered stock solution into a beaker and mix well, wherein the molar ratio of manganese element in potassium permanganate to manganese element in the graphite oxide filtered stock solution is 3.6, the manganese element content in the graphite oxide filtered stock solution is 19 g / L in terms of divalent manganese ions, the potassium element content in terms of potassium ions is 13 g / L, the sulfur element content in terms of sulfate ions is 69 g / L, and the carbon element content in terms of carbon atoms is 1.2 g / L;
[0052] b. The mixture was hydrothermally treated at 110°C under autogenous pressure for 12 h;
[0053] c. filtering, washing, and drying at 100° C. for 12 h to obtain a dry solid product;
[0054] d. The solid product was calcined at a temperature of 350°C for 2 h to obtain a manganese oxide material.
[0055] Example 2
[0056] 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 6.
[0057] Example 3
[0058] The preparation method in Example 1 was used, except that in step d, the calcination temperature was 800° C. and the calcination time was 1 hour.
[0059] Example 4
[0060] The preparation method in Example 1 is adopted, except that in step d, no calcination is performed.
[0061] Example 5
[0062] The preparation method in Example 1 was adopted, except that in step c, the hydrothermal temperature was 180°C.
[0063] Example 6
[0064] The preparation method in Example 1 is adopted, except that, in step a, the manganese content in the filtered stock solution of graphite oxide is 21 g / L as divalent manganese ions, the potassium content in potassium ions is 16 g / L, the sulfur content in sulfate ions is 33 g / L, and the carbon content in carbon atoms is 0.7 g / L; wherein the molar ratio of manganese element in the potassium permanganate aqueous solution to manganese element in the filtered stock solution of graphite oxide is consistent with that in Example 1.
[0065] Comparative Example 1
[0066] 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 stock solution.
[0067] Comparative Example 2
[0068] The preparation method in Example 1 is adopted, except that in step a, the molar ratio of the manganese element in potassium permanganate to the manganese element in the graphite oxide stock solution is 1:1.
[0069] Test Case
[0070] The manganese oxides of Examples 1 to 6 and Comparative Examples 1 to 2 were tested as follows:
[0071] 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.
[0072] The element content of the sample was determined by XPS on a VGESCA-LABS X-ray photoelectron spectrometer, using Mg Kα X-rays as the laser source and the C1s binding energy (284.6 eV) of the surface contamination carbon to calibrate the binding energy of each element in the desulfurizer surface species.
[0073] The warm nitrogen adsorption and desorption test (BET) was carried out on a JW-BK200C surface area and pore size analyzer produced by Beijing Jingwei Gaobo Co., Ltd. The surface area and pore volume were calculated using the two-parameter BET equation, and the pore distribution was calculated using the BJH method.
[0074] The sulfide content in the hydrogen after adsorption by the adsorbent was analyzed by online chromatography (Nexis-2030, Shimadzu Corporation, Japan) and SCD fluorescence detector (SCD-2030).
[0075] 300 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 mass content of hydrogen sulfide in the hydrogen raw gas is 500 ppm. The hydrogen raw gas is introduced at a flow rate of 30 ml / min at 120 ° C and 2.1 MPa for purification reaction. The hydrogen sulfide content in the purified hydrogen is analyzed online, and the analysis cycle is once every 5 minutes. The time is counted from the time when hydrogen is introduced to the time when the hydrogen sulfide content in the purified hydrogen exceeds 20 ppb. The penetration time test results of each sample are shown in Table 1, and other characterization results of the prepared product are shown in Table 2.
[0076] Table 1
[0077] Breakthrough time / min Example 1 245 Example 2 180 Example 3 145 Example 4 185 Example 5 130 Example 6 175 Comparative Example 1 25 Comparative Example 2 115
[0078] Table 2
[0079]
[0080] According to the test results in Table 1 and Table 2, it can be seen that the manganese oxide material prepared by the preparation method provided by the present invention has a longer hydrogen feed gas penetration time than the comparative example, and exhibits more excellent performance in the hydrogen purification reaction. The sulfide content in the purified hydrogen can meet the content requirements of sulfide impurities in hydrogen for fuel cells, and the manganese element in the graphite oxide filtration stock solution is fully utilized to reduce the preparation cost of the manganese oxide material.
[0081] It can be seen from the test results of Examples 1 to 6 that when the molar ratio of the manganese element in the manganese source in the filtered stock solution of graphite oxide to the manganese element in the filtered stock solution of graphite oxide, the preparation method of the filtered stock solution of graphite oxide, the element content in the filtered stock solution of graphite oxide, the conditions of hydrothermal 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.
[0082] 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 treatment, resulting in a short penetration time of the hydrogen raw gas; 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 manganese source is low, and therefore the performance of the prepared manganese oxide material is poor, resulting in a hydrogen raw gas penetration time that is significantly shorter than that in Example 1.
[0083] 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.
[0084] 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.
[0085] 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 manganese oxide material, the method comprising: (1) mixing a manganese source with a filtered stock solution of graphite oxide and optionally water to obtain a mixed solution, wherein the molar ratio of manganese element in the manganese source to manganese element in the filtered stock solution of graphite oxide is 3 or more; (2) The mixed solution is subjected to hydrothermal treatment under hydrothermal autogenous pressure and atmosphere, and the obtained material is filtered, washed, dried and optionally calcined to obtain the manganese oxide material.
2. The method according to claim 1, wherein: The molar ratio of the manganese element in the manganese source to the manganese element in the filtered raw solution of graphite oxide is 3-5.
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: Calculated on the basis of the manganese element in the filtered stock solution of graphite oxide, the amount of the manganese source used is 2 to 60 mol parts, preferably 5 to 30 mol parts, and the amount of water used is 0 to 500 mol parts, preferably 0 to 200 mol parts, relative to 100 mol parts of the filtered stock solution of graphite oxide.
5. The method according to claim 1, wherein: The filtered stock solution of graphite oxide is obtained by preparing graphite oxide according to the improved Hummer method and then performing solid-liquid separation; No nitrate is added during the reaction of the improved Hummer method; 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 1.5-25 g / L, the sulfur content calculated as sulfate ions is 20-200 g / L, and the carbon content calculated as carbon atoms is 0.2-10 g / L.
6. The method according to claim 1, wherein: The conditions of the hydrothermal treatment include: a temperature of 80 to 180°C and a time of 1 to 72 hours; preferably, a temperature of 100 to 140°C and a time of 2 to 24 hours; The calcination conditions include: a temperature of 200 to 800° C., a time of 1 to 12 hours, and a pressure of 0.1 to 0.5 MPa.
7. A manganese oxide material prepared by the method according to any one of claims 1 to 6.
8. The manganese oxide material according to claim 7, wherein The XRD spectrum of the manganese oxide material has a characteristic peak of β-MnO2; wherein, based on the mass of the manganese oxide material, the Mn element content in the manganese oxide material is 25 to 50 weight %, preferably 30 to 45 weight %; the S element content is 0.5 to 12 weight %, preferably 1 to 8 weight %; and the K element content is 1 to 15 weight %, preferably 2 to 10 weight %.
9. The manganese oxide material according to claim 7, wherein: The manganese oxide material is black needle-shaped powder particles, and the average length of the needle-shaped powder particles is less than 0.5 mm; The specific surface area of the manganese oxide material is 5 to 100 m 2 / g, pore volume is 0.02-0.2 ml / g; preferably, specific surface area is 15-50 m 2 / g, and the pore volume is 0.05~0.1ml / g.
10. A method for purifying hydrogen, the method comprising: At a temperature of 60 to 180° C., hydrogen is contacted with the manganese oxide material according to any one of claims 7 to 9 to perform a purification reaction; Optionally, the reaction conditions of the hydrogen purification method include: temperature of 60-180°C, pressure of 0.1-5.0 MPa, and space velocity of 10-5000 h -1 ; The mass content of sulfide in the hydrogen is less than 1000 ppm, and the content of sulfide in the hydrogen is calculated as hydrogen sulfide.