A method for purifying hydrogen

Abstract

The present invention relates to a method for purifying hydrogen, comprising: contacting hydrogen with a manganese-based adsorbent material at a temperature below 50°C to perform a purification reaction to produce purified hydrogen. The manganese-based adsorbent material is obtained by hydrothermally treating a mixture of manganese sources under hydrothermal autogenous pressure and atmosphere. The method can purify hydrogen under mild conditions. The purified hydrogen contains less than 4 ppb of sulfide, enabling direct use as a hydrogen supply for fuel cells.

Description

Technical Field

[0001] The invention relates to a hydrogen purification method. Background Art

[0002] Hydrogen is an important 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 poison the fuel cell electrode catalysts, thereby reducing their efficiency. Therefore, there are strict requirements on the sulfide content of hydrogen used in fuel cells. The international requirement is that the sulfide content calculated as hydrogen sulfide must 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 the use of hydrogen in fuel cells. Existing desulfurization technologies are mostly aimed at conventional sulfide contents (>0.1%), and there are few reports on desulfurization technologies for trace amounts such as sulfides below 100ppm. Summary of the Invention

[0003] The present invention aims to provide a hydrogen purification method that can purify hydrogen containing trace amounts of sulfides, such as less than 100 ppm, under mild conditions, such as at a temperature below 50°C. The sulfide content in the purified hydrogen is less than 4 ppb and can be directly used to supply hydrogen to fuel cells.

[0004] To achieve the above objectives, the present invention provides a method for purifying hydrogen, comprising: contacting hydrogen with a manganese-based adsorption material at a temperature below 50° C. to perform a purification reaction to obtain purified hydrogen, wherein the sulfide content in the purified hydrogen is less than 4 ppb, wherein the manganese-based adsorption material is obtained by hydrothermally treating a mixture of a manganese source 1 and a manganese source 2 under a hydrothermal autogenous pressure and atmosphere.

[0005] The temperature of the hydrogen purification reaction can be from room temperature to 50°C.

[0006] Optionally, the manganese-based adsorption material is a black powder with a particle size of less than 20 mesh.

[0007] The manganese-based adsorption material has a Mn content of 15-45% by mass, preferably 20-40%; a S content of 0.5-8% by mass, preferably 1-4% by mass; a K content of 1-10% by mass, preferably 2-8% by mass; and optionally contains other metal elements, such as Cu, Fe, Zn, etc., with a content of 0-20% by mass, preferably 1-10% by mass; the balance is O.

[0008] In the XRD spectrum of the manganese-based adsorption material, 2θ peaks appear at positions such as 12.8±0.2°, 18.1±0.2°, 28.8±0.2°, 36.7±0.2°, 37.5±0.2°, 42.0±0.2°, 49.9±0.2°, 56.4±0.2°, and 60.3±0.2°.

[0009] The specific surface area of ​​the manganese-based adsorption material is 80-200m 2 / g, preferably 100-150m 2 / g; pore volume range 0.1-0.8ml / g, preferably 0.2-0.6ml / g.

[0010] In some embodiments, the specific surface area is 120-150m 2 / g, pore volume range 0.2-0.6ml / g.

[0011] The preparation method of the manganese-based adsorption material comprises: in the presence of an optional acid source, mixing materials including a manganese source 1 with a manganese source 2, and then performing hydrothermal treatment to obtain the manganese-based adsorption material.

[0012] Optionally, the weight ratio of the manganese source 1 to the acid source in the mixture is 100:(0-500), preferably 100:(0.5-200), and more preferably 100:(0.5-150).

[0013] Optionally, the method further comprises preparing the manganese-based adsorption material by the following steps:

[0014] (1) Mixing a manganese source 1 with water at a mass ratio of 1:(10-100) under stirring at room temperature and pressure, and optionally adding an acid source to the mixture to obtain a manganese source 1 solution;

[0015] (2) adding the manganese source 2 to the manganese source 1 solution under stirring at room temperature and pressure to obtain a mixed solution;

[0016] (3) subjecting the mixed solution to hydrothermal crystallization treatment, taking it out and drying it, and optionally roasting it to obtain the manganese-based adsorption material.

[0017] Optionally, the manganese source 2 is partially provided by a filtered raw solution of graphite oxide, wherein the molar ratio of the manganese element provided by the filtered raw solution of graphite oxide to the manganese source 2 is 5-50%.

[0018] The graphite oxide filter stock solution is obtained by oxidizing graphite according to Hummer's method (without adding nitrate) and then performing solid-liquid separation. The graphite oxide filter stock solution is an aqueous solution, which, in addition to hydrogen and oxygen, mainly contains elements such as manganese, potassium, sulfur, and carbon. In the stock solution, the manganese content calculated as divalent manganese ions is 5-100 g / L, the potassium content calculated as potassium ions is 1-50 g / L, the sulfur content calculated as sulfate ions is 10-200 g / L, and the carbon content calculated as carbon atoms is 1-20 g / L (the carbon element is basically or mainly derived from the soluble graphite oxide remaining in the stock solution).

[0019] The acid source is selected from one or more of sulfuric acid, nitric acid and hydrochloric acid.

[0020] The valence of the manganese element in the manganese source 1 is greater than trivalent, and can be selected from one or more inorganic salts containing high-valent manganese (greater than trivalent), such as potassium permanganate, potassium manganate, sodium permanganate and sodium manganate.

[0021] The valence of the manganese element in the manganese source 2 is less than or equal to trivalent, and can be selected from one or more inorganic salts containing low-valent manganese (less than or equal to trivalent), such as manganese sulfate, manganese nitrate, manganese phosphate and manganese chloride; or a combination of one or more of them and a filtered stock solution of graphite oxide.

[0022] Optionally, the manganese-based adsorption material particles have an average width and thickness of 5-100 nm and an average length of 200-5000 nm, wherein the ratio of width to thickness is 1:0.5-2. This can be determined by transmission electron microscopy testing, where 100 randomly selected manganese-based adsorption material particles are statistically analyzed for their average width, thickness, and length using transmission electron microscopy images.

[0023] The molar ratio of the manganese source 1, the manganese source 2 and water is 0.2-2.5:1:5-100, preferably 0.4-2.0:1:10-100, wherein the manganese source 1 and the manganese source 2 are calculated as manganese element.

[0024] The crystallization temperature is 80-200° C. and the time is 1-72 hours, preferably 100-150° C. and the time is 2-24 hours.

[0025] The calcination temperature is 200-800° C., preferably 250-500° C., the calcination time is 1-12 hours, and the calcination pressure is 0.1-0.5 MPa.

[0026] Optionally, the conditions for the hydrogen purification reaction include: temperature of 20-50°C, pressure of 0.1-5.0 MPa, and space velocity of 500-500000h -1The sulfide content in the hydrogen is less than or equal to 1000 ppm as hydrogen sulfide. The sulfide content before and after purification can be monitored online, for example, by analyzing the sulfide content in the hydrogen after adsorption by the adsorbent using an online chromatograph (Shimadzu Nexis-2030) and an SCD fluorescence detector (SCD-2030).

[0027] The hydrogen before purification contains 0.1-1000 ppm of sulfide, preferably 1-100 ppm of sulfide, wherein the sulfide is hydrogen sulfide.

[0028] The manganese-based adsorption material obtained by the method of the present invention has excellent performance when used in a hydrogen purification reaction, and the purified hydrogen can meet the standard requirements for hydrogen used in fuel cells.

[0029] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the XRD pattern of the product in Preparation Example 1. DETAILED DESCRIPTION

[0031] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0032] The present invention is further illustrated below by way of examples, but the present invention is not limited thereto. The reagents used in the present invention are all commercially available analytically pure reagents.

[0033] The preparation examples are used to illustrate the manganese-based adsorption material and the preparation method thereof of the present invention, and the preparation comparative examples are used to illustrate a preparation method of an adsorption material different from that of the present invention.

[0034] In the preparation example, the graphite oxide filter stock solution is obtained by oxidizing graphite according to Hummer's method (without adding nitrate) and then performing solid-liquid separation. The graphite oxide filter stock solution is an aqueous solution, which, in addition to hydrogen and oxygen elements, mainly contains 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 3.2 g / L (the main source of carbon is the soluble graphite oxide remaining in the stock solution).

[0035] Preparation Example 1

[0036] (1) Under normal temperature and pressure, 50 mL of water, 1 mL of concentrated sulfuric acid (mass concentration greater than 98%), and 5 g of potassium permanganate were added to a beaker and mixed to obtain a manganese source 1 solution;

[0037] (2) manganese sulfate and filtered graphite oxide stock solution are used as manganese source 2 (the molar ratio of manganese element provided by the filtered graphite oxide stock solution to manganese source 2 is 10%), and are added to the manganese source 1 solution of step (1) to obtain a mixed solution; the molar ratio of the added manganese source 2 to the manganese source 1 is 1:1.2 based on the manganese element;

[0038] (3) hydrothermally treating the mixture obtained in step (2) at 140° C. under autogenous pressure for 12 h;

[0039] (4) The manganese-based adsorption material obtained after hydrothermal treatment was dried at 80°C for 6 hours and then calcined at a temperature of 300°C for 4 hours.

[0040] The obtained sample is a black powder with a particle size of less than 20 mesh. The sample particles are needle-like fibers with an average width and thickness of about 10nm and an average length of 800nm, where the ratio of width to thickness is about 1:1. The sample was further characterized and its Mn content was 32%, S content was 2.1%, K content was 3.5%, and the balance was O element. The 2θ in XRD showed peaks at 12.8±0.2°, 18.1±0.2°, 28.8±0.2°, 36.7±0.2°, 37.5±0.2°, 42.0±0.2°, 49.9±0.2°, 56.4±0.2°, 60.3±0.2°, etc. The specific surface area is 141m 2 / g, pore volume range 0.36ml / g.

[0041] Preparation Example 2

[0042] The manganese-based adsorption material A2 was prepared by the same method as that of Example 1, except that in step (4), the calcination temperature was 800° C. and the calcination time was 1 hour.

[0043] Preparation Example 3

[0044] The manganese-based adsorption material A3 was prepared in the same manner as in Example 1, except that the calcination step (4) was omitted.

[0045] Preparation Example 4

[0046] The manganese-based adsorption material A4 was prepared in the same manner as in Example 1, except that in step (3), the crystallization temperature was 160°C.

[0047] Preparation Example 5

[0048] The manganese-based adsorption material A5 was prepared by the same method as in Example 1, except that in step (2), the molar ratio of the added manganese source 2 to the manganese source 1 was 1:0.25, calculated on the basis of manganese element.

[0049] Preparation Example 6

[0050] The manganese-based adsorption material A6 was prepared by the same method as in Example 1, except that in step (2), the manganese element provided by the filtered raw solution of graphite oxide accounted for 60% by mole of the manganese source 2.

[0051] Preparation Example 7

[0052] The manganese-based adsorption material A7 was prepared by the same method as in Example 1, except that concentrated sulfuric acid was not added in step (1) to obtain the manganese source 1 solution.

[0053] Preparation Comparative Example 1

[0054] The manganese-based adsorption material DA1 was prepared by the same method as in Example 1, except that in step (2), an equal amount of water was used to replace the graphite oxide stock solution.

[0055] Preparation Comparative Example 2

[0056] The manganese-based adsorption material DA1 was prepared by the same method as in Example 1, except that in step (2), the manganese source 2 was provided only by manganese sulfate with an equal manganese element content.

[0057] The examples are used to illustrate the method of purifying hydrogen using the manganese-based adsorption material of the present invention. The comparative examples are used to illustrate the method of purifying hydrogen using an adsorption material different from that of the present invention.

[0058] The sulfide content in hydrogen after adsorption by the adsorbent was analyzed using an online chromatograph (Nexis-2030, Shimadzu Corporation, Japan) and a SCD fluorescence detector (SCD-2030).

[0059] Example 1

[0060] 250 mg of manganese-based adsorption material A1 was loaded as a catalyst into the constant temperature section of a passivated fixed-bed microreactor with an inner diameter of 12 mm and a length of 500 mm, top and bottom filled with quartz sand. The hydrogen sulfide content of the standard hydrogen feed gas was 1000 ppm. Hydrogen was introduced at a flow rate of 200 ml / min at 40°C and 2.1 MPa for purification. The hydrogen sulfide content of the purified hydrogen was analyzed online. The breakthrough time was calculated from the start of hydrogen introduction until the hydrogen sulfide content in the purified hydrogen exceeded 0.004 ppm. The results are listed in Table 1.

[0061] Examples 2-7

[0062] Examples 2-7 respectively use the same method as Example 1 to purify hydrogen, with the only difference being that Examples 2-7 respectively use manganese-based adsorption materials A2-A7 as catalysts.

[0063] Comparative Example 1-2

[0064] The same method as in Example 1 was used to purify hydrogen, except that the adsorption material prepared in Comparative Example 1-2 was used as a catalyst.

[0065] Table 1

[0066] Adsorbent source Breakthrough time, min Example 1 Preparation Example 1 169 Example 2 Preparation Example 2 141 Example 3 Preparation Example 3 128 Example 4 Preparation Example 4 93 Example 5 Preparation Example 5 106 Example 6 Preparation Example 6 97 Example 7 Preparation Example 7 132 Comparative Example 1 Preparation Comparative Example 1 64 Comparative Example 2 Preparation Comparative Example 2 79

[0067] As can be seen from Table 1, the method of the present invention can effectively remove trace sulfides in hydrogen.

Claims

1. A method for purifying hydrogen, the method comprising: contacting hydrogen with a manganese-based adsorption material at a temperature below 50° C. for a purification reaction to obtain purified hydrogen, wherein the sulfide content in the purified hydrogen is less than 4 ppb, wherein the manganese-based adsorption material is obtained by hydrothermally treating a mixture of a manganese source 1 and a manganese source 2 under a hydrothermal autogenous pressure and atmosphere; The manganese source 2 is at least partially provided by a filtered stock solution of graphite oxide, wherein the molar ratio of manganese element provided by the filtered stock solution of graphite oxide to the manganese source 2 is 5-50%. The graphite oxide is prepared by Hummer's method without using nitrate in the preparation process.

2. The method according to claim 1, wherein The preparation method of the manganese-based adsorption material comprises: mixing the manganese source 1 with an optional acid source, wherein the acid source is selected from one or more of sulfuric acid, nitric acid and hydrochloric acid, and the weight ratio of the manganese source 1 to the acid source is 100:(0-500).

3. The method according to claim 2, wherein: The weight ratio of the manganese source 1 to the acid source is 100:(0.5-200).

4. The method according to claim 1, wherein The valence of the manganese element in the manganese source 1 is greater than trivalence, and the valence of at least part of the manganese element in the manganese source 2 is less than or equal to trivalence.

5. The method according to claim 1, wherein The preparation method of the manganese-based adsorption material comprises the following steps: (1) Mixing a manganese source 1 with water at a mass ratio of 1:(10-100) under stirring at room temperature and pressure, and optionally adding an acid source to the mixture to obtain a manganese source 1 solution; (2) adding the manganese source 2 to the manganese source 1 solution under stirring at room temperature and pressure to obtain a mixed solution; (3) subjecting the mixed solution to hydrothermal crystallization treatment, taking it out and drying it, and optionally roasting it to obtain the manganese-based adsorption material.

6. The method according to claim 5, wherein: The manganese source 2 is a filtered stock solution of graphite oxide, wherein the manganese content in the filtered stock solution is 5-100 g / L as divalent manganese ions, the potassium content is 1-50 g / L as potassium ions, the sulfur content is 10-200 g / L as sulfate ions, and the carbon content is 1-20 g / L as carbon atoms.

7. The method according to claim 5, wherein: The particle size of the manganese-based adsorption material is less than 20 mesh; the specific surface area is 80-200m 2 / g; pore volume range 0.1-0.8ml / g.

8. The method according to claim 7, wherein: The specific surface area of ​​the manganese-based adsorption material is 100-150m 2 / g; pore volume range 0.2-0.6ml / g.

9. The method according to claim 5, wherein: The manganese-based adsorption material has a Mn content of 15-45% by mass, a S content of 0.5-8% by mass, a K content of 1-10% by mass, and optionally contains other metal elements with a content of 0-20% by mass; the balance is O.

10. The method according to claim 9, wherein: The manganese-based adsorption material has a Mn content of 20-40% by mass, a S content of 1-4% by mass, a K content of 2-8% by mass, and optionally contains other metal elements with a content of 1-10% by mass; the balance is O.

11. The method according to claim 5, wherein: In the XRD pattern of the manganese-based adsorption material, 2θ peaks appear at 12.8±0.2°, 18.1±0.2°, 28.8±0.2°, 36.7±0.2°, 37.5±0.2°, 42.0±0.2°, 49.9±0.2°, 56.4±0.2° and 60.3±0.2°.

12. The method according to claim 1, wherein The conditions of the hydrogen purification reaction include: temperature of 20-50°C, pressure of 0.1-5.0 MPa, and space velocity of 500-500000 h -1 ; The sulfide content in the hydrogen is less than or equal to 1000 ppm in terms of hydrogen sulfide.

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