A hydrogen purification material and preparation and application thereof

Abstract

The application belongs to the field of hydrogen purification, and specifically discloses a hydrogen purification material and preparation and application thereof. The hydrogen purification material is a composite of silicon chrysocolla structure copper silicate and A-type molecular sieve, wherein the content of the silicon chrysocolla structure copper silicate is 30-70%, and the balance is A-type molecular sieve. The silicon chrysocolla structure copper silicate is prepared from a copper ammonia solution and a silica sol through co-precipitation, washing, drying and calcination, and then is compounded with A-type molecular sieve to be formed. The purification material can simultaneously remove trace amounts of CO, O2 and sulfur in high-purity hydrogen at 60-120 DEG C, and meets the requirements of the national standard GB / T37244-2018 for hydrogen used for fuel cell vehicles.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen purification, specifically relating to a hydrogen purification material and its preparation and application, used to simultaneously remove trace amounts of impurities such as CO, O2 and sulfur from high-purity hydrogen. Background Technology

[0002] Hydrogen energy will be one of the main energy sources for future society, and countries around the world have included it in their national development strategies. As the primary fuel for proton exchange membrane fuel cells (PEMFCs), the quality of hydrogen significantly impacts the cell's performance. When hydrogen is derived from fossil fuel reforming, industrial byproducts, or water electrolysis, it contains impurities and byproducts introduced from the raw materials, such as trace amounts of CO, O2, sulfur, aldehydes, acids, ammonia, and halogens. The presence of these impurities affects the stable operation of PEMFCs, significantly shortening their efficiency and lifespan. Therefore, it is essential to control the impurity content in the hydrogen used in fuel cells.

[0003] The national standard GB / T37244-2018 for hydrogen used in fuel cell vehicles requires CO ≤ 0.2 ppm, O2 ≤ 5 ppm, and sulfur ≤ 0.004 ppm. Currently, hydrogen for fuel cell vehicles is not widely used. The purity of hydrogen is mainly improved by small-scale PSA (Power Suction Assembly). The CO, O2, and sulfur impurities after purification are mainly purified separately, without a systematic solution.

[0004] Currently, the most extensive research is on the removal of O2 from hydrogen. Catalytic combustion catalysts based on noble metal systems are commonly used to react hydrogen and oxygen to produce water. This technology is mature and has been widely applied in industry.

[0005] Sulfur is a common poison for industrial catalysts, and research on sulfur removal is extensive and in-depth. Generally, based on the downstream catalyst's tolerance to sulfur, desulfurization is classified into coarse desulfurization (~1ppm), fine desulfurization (<0.1ppm), and deep fine desulfurization (<0.01ppm). The index of <0.004ppm in hydrogen used in fuel cell vehicles is the most stringent, and copper-zinc compounds are effective desulfurization materials.

[0006] There are four main methods for removing CO from hydrogen: cryogenic removal, pressure swing adsorption (PSA), catalytic oxidation, methanation, and complexation removal. Among these, cryogenic removal is only feasible when the gas volume reaches hundreds of thousands of Nm³. 3The use of PSA in large-scale plants is almost uneconomical for the current smaller hydrogen energy industry, and its CO removal accuracy cannot meet the national standard requirement of <0.2ppm. Pressure swing adsorption (PSA) is a widely used purification and separation method, applicable to small and medium-sized industrial plants. PSA improves hydrogen purity to meet the national standard requirement of >99.97%, while also removing most impurities, including CO. However, its CO removal accuracy cannot meet the national standard. Currently, a two-step method using PSA and directional purification materials is generally employed to remove CO from hydrogen. Catalytic oxidation for CO removal is currently a research hotspot, focusing on improving catalytic oxidation selectivity and low-temperature activity. Catalytic oxidation is mainly used for purifying CO content in methanol cracking and hydrocarbon hydrogen production to <100ppm. It is ineffective at removing CO of several to tens of ppm after PSA treatment. Methanation for CO removal has significant drawbacks: it consumes three times the volume of hydrogen while removing CO; the removal temperature is high, resulting in poor economics for industrial applications; and the CO removal accuracy cannot meet the national standard requirement of <0.2ppm. Utilizing Cu... + There are many studies on CO removal from gases by COπ conjugation complexation. Among them, the PU-1CO adsorbent developed by Professor Xie Youchang of Peking University under the guidance of monolayer distribution theory is the most successful and has been successfully applied in large-scale industrial plants to purify and separate CO from gases. However, the complexation method is generally used for the purification and separation of constant CO in gases and cannot meet the national standard requirement of CO < 0.2 ppm.

[0007] Another method for CO removal is to use a carrier to load highly dispersed CuO material to react with CO and oxidize CO to CO2. However, this material is generally used for the removal of trace amounts of CO in inert materials such as hydrocarbons, and cannot be used in hydrogen-containing sources, especially in high-purity hydrogen sources such as hydrogen for fuel cell vehicles, because hydrogen is also a reducing gas. The reaction between hydrogen and CuO will cause the material to quickly fail and become unable to react with CO to remove it.

[0008] If CO, O2, and sulfur are removed separately using conventional techniques, it will lead to excessive impurities, causing the hydrogen quality to fail to meet national standards. Furthermore, the purification process is complex, cumbersome, requires large amounts of purification materials, and incurs high operating costs, increasing the cost of hydrogen for fuel cell vehicles and severely reducing their competitiveness, thus seriously hindering the development of my country's hydrogen energy industry. To simplify the process, the market urgently needs a purification material that can simultaneously remove CO, O2, and sulfur, meeting the requirements of the national standard GB / T37244-2018 for hydrogen used in fuel cell vehicles. Summary of the Invention

[0009] The technical problem to be solved by this invention is to address the shortcomings of existing technologies by providing a hydrogen purification material and its preparation and application. It can simultaneously purify and remove CO, O2, and sulfur impurities, meeting the requirements of the national standard GB / T37244-2018 for hydrogen used in fuel cell vehicles: CO ≤ 0.2 ppm, O2 ≤ 5 ppm, and sulfur ≤ 0.004 ppm.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0011] The first aspect of the present invention provides a hydrogen purification material, which is a composite of copper silicate with a chalcocite structure and a type A molecular sieve, wherein the content of copper silicate with a chalcocite structure is 30-70%, and the balance is a type A molecular sieve.

[0012] According to the above scheme, the hydrogen purification material is prepared by co-precipitation, washing, drying, and calcination of copper ammonia solution and silica sol to obtain copper silicate with a silicomallic structure, which is then compounded with type A molecular sieves and shaped. Further, the copper silicate with the silicomallic structure can be mixed with a certain proportion of type A molecular sieves, ball-milled uniformly, and then sheeted to obtain the final product.

[0013] According to the above scheme, the specific calcination temperature in this invention is 350-400℃.

[0014] According to the above scheme, the type A molecular sieve is a 3A, 4A, or 5A molecular sieve, which can be commercially available.

[0015] Typical chemical composition of 3A molecular sieve: Typical chemical composition of 4A molecular sieve: Typical chemical composition of 5A molecular sieve:

[0016] According to the above scheme, the molar ratio of CuO to SiO2 in copper silicate with a chalcocite structure is 0.1 to 0.5:1.

[0017] A second aspect of the present invention provides a method for preparing the above-mentioned hydrogen purification material, which includes the following steps:

[0018] (1) Prepare 0.05-1.0 mol / L copper ammonia solution and 0.1-1.0 mol / L silica sol, and pour them into a container with a stirrer and stir until homogeneous;

[0019] (2) The above solution is evaporated by steam heating, and the evaporated material is repeatedly washed with reverse osmosis pure water. The filtered material is dried at 100-150°C and then calcined at 350-400°C for 3-6 hours to obtain copper silicate with malachite structure.

[0020] (3) A type molecular sieve was added to copper silicate with a chalcocite structure in a certain proportion, ball milled, and shaped into sheets to obtain hydrogen purification material with a chalcocite structure.

[0021] According to the above scheme, the molar ratio of CuO to SiO2 in copper silicate with a chalcocite structure is 0.1 to 0.5:1.

[0022] According to the above scheme, the copper ammonia solution is a solution generated by the reaction of copper salt and ammonia source substance. The ammonia source substance is 1.5 to 2 times the theoretical amount. The copper salt is selected from one or more combinations of copper nitrate, copper acetate, and copper chloride. The ammonia source substance is selected from one or more combinations of ammonia water, urea, and ammonium bicarbonate. The silica sol is a solution prepared from commercially available silica sol.

[0023] The third aspect of the present invention provides the application of the above-mentioned hydrogen purification material in the simultaneous purification and removal of CO, O2 and sulfur impurities from hydrogen-containing source gas.

[0024] According to the above scheme, the purification and removal temperature is 60-120℃.

[0025] According to the above scheme, the application is used for hydrogen purification in fuel cell vehicles, to simultaneously purify and remove CO, O2, and sulfur impurities from high-purity hydrogen to obtain hydrogen for fuel cell vehicles. In this invention, the hydrogen source gas can be hydrogen from different sources, such as coal-derived hydrogen, methanol cracking hydrogen, industrial by-product hydrogen, and water electrolysis hydrogen. Furthermore, to obtain high-purity hydrogen with increased purity through purification treatments such as pressure swing adsorption or cryogenic treatment, the purification treatment mainly aims to increase the hydrogen purity to over 99.9%, while simultaneously removing a large number of impurities.

[0026] The hydrogen purification material of the present invention can simultaneously remove trace amounts of CO, O2 and sulfur from high-purity hydrogen at a temperature of 60-120°C. After purification, the impurities such as CO, O2 and sulfur meet the requirements of the national standard GB / T37244-2018 for hydrogen used in fuel cell vehicles: CO≤0.2ppm, O2≤5ppm, and sulfur≤0.004ppm.

[0027] The main advantages of this patent are:

[0028] (1) The copper silicate purification material with a malachite structure of the present invention will not be reduced by hydrogen at a temperature below 160°C, and can be used to remove trace amounts of CO from high-purity hydrogen. The removal principle is as follows:

[0029] CO+2CuO·nSiO2==Cu2O·nSiO2+CO2

[0030] CO+CuO·nSiO2==Cu·nSiO2+CO2

[0031] (2) The copper silicate purification material with a chalcocite structure reduces the copper valence state to +1 or 0 after removing trace amounts of CO, and can also remove O2 and sulfur. The principle is as follows:

[0032] Cu2O·nSiO2+1 / 2O2==2CuO·nSiO2

[0033] Cu·nSiO2+1 / 2O2==CuO·nSiO2

[0034] Cu2O·nSiO2+H2S==Cu2S·nSiO2+H2O

[0035] Cu·nSiO2+H2S==CuS·nSiO2+H2

[0036] (3) After being mixed with type A molecular sieve and ball-milled, the silica malachite material is uniformly dispersed on type A molecular sieve, which greatly increases the specific surface area and exposes more copper elements at the active sites to the gas source, thereby improving the purification material’s ability to remove CO, O2 and sulfur. Attached Figure Description

[0037] Figure 1 These are X-ray diffraction patterns of fresh copper silicate samples prepared under this patent, samples reduced with hydrogen, and samples directly used to remove CO, O2, and sulfur from hydrogen. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] Example 1:

[0040] 2 L of a 0.05 mol / L copper ammonia solution was prepared using copper nitrate and ammonia water. 2 L of a 0.3 mol / L silica sol solution was prepared using commercially available 20% silica sol. Both solutions were then added to a container with a stirrer and stirred until homogeneous. The solution was evaporated to dryness by steam heating. The material was repeatedly washed with reverse osmosis purified water, and the filtered material was dried at 120°C and then calcined at 350°C for 3 hours to obtain ~44 g of copper silicate with a chalcocite structure. 22 g of 3A molecular sieve was then added and ball-milled for 5 hours. The mixture was then sheeted to obtain ~66 g of purified material A1 with a chalcocite structure.

[0041] The molar ratio of CuO to SiO2 in Al is 0.17, and the content of copper silicate with a silicomall structure is 67%.

[0042] Example 2:

[0043] 1 L of a 0.2 mol / L copper ammonia solution was prepared using copper acetate and urea. 1 L of a 0.4 mol / L silica sol solution was prepared using commercially available 20% silica sol. Both solutions were then added to a container with a stirrer and stirred until homogeneous. The solution was evaporated to dryness using steam heating. The material was repeatedly washed with reverse osmosis purified water, and the filtered material was dried at 130°C and then calcined at 400°C for 4 hours to obtain approximately 40 g of copper silicate with a chalcocite structure. 80 g of 4A molecular sieve was then added and ball-milled for 5 hours. The mixture was then sheeted to obtain approximately 120 g of purified material A2 with a chalcocite structure.

[0044] In A2, the molar ratio of CuO to SiO2 is 0.5, and the content of copper silicate with a diatomaceous malachite structure is 33%.

[0045] Example 3:

[0046] 0.5 L of a 0.5 mol / L copper ammonia solution was prepared using copper chloride and ammonium bicarbonate. 1 L of a 0.75 mol / L silica sol solution was prepared using commercially available 20% silica sol. Both solutions were then added to a stirred container and stirred until homogeneous. The solution was evaporated to dryness using steam heating. The material was repeatedly washed with reverse osmosis purified water, and the filtered material was dried at 140°C and then calcined at 375°C for 3 hours to obtain approximately 65 g of copper silicate with a chalcocite structure. 65 g of 5A molecular sieve was then added and ball-milled for 5 hours. The mixture was then sheeted to obtain approximately 130 g of purified material A3 with a chalcocite structure.

[0047] The molar ratio of CuO to SiO2 in A3 is 0.33, and the content of copper silicate with a chrysocolla structure is 50%.

[0048] Example 4:

[0049] 0.25 L of a 0.07 mol / L copper ammonia solution was prepared using copper nitrate and ammonium bicarbonate. 0.5 L of a 1.0 mol / L silica sol solution was prepared using commercially available 20% silica sol. Both solutions were added to a stirred container and stirred until homogeneous. The solution was evaporated to dryness by steam heating. The material was repeatedly washed with reverse osmosis purified water, and the filtered material was dried at 150°C and then calcined at 350°C for 6 hours to obtain ~44 g of copper silicate with a chalcocite structure. 56 g of 3A molecular sieve was then added and ball-milled for 5 hours. The mixture was then sheeted to obtain ~66 g of purified material A4 with a chalcocite structure.

[0050] The molar ratio of CuO to SiO2 in A4 is 0.35, and the content of copper silicate with a silicomall structure is 44%.

[0051] Example 5:

[0052] 0.1 L of a 1.0 mol / L copper ammonia solution was prepared using copper acetate and ammonia water. 0.5 L of a 0.8 mol / L silica sol solution was prepared using commercially available 20% silica sol. The solutions were then added to a container with a stirrer and stirred until homogeneous. The solution was evaporated to dryness by steam heating. The material was repeatedly washed with reverse osmosis purified water and then dried at 110°C. The material was then calcined at 400°C for 5 hours to obtain ~32 g of copper silicate with a chrysocolla structure. 48 g of 4A molecular sieve was added and the mixture was ball-milled for 5 hours. The mixture was then sheeted to obtain ~80 g of purified material A5 with a chrysocolla structure.

[0053] In A5, the molar ratio of CuO to SiO2 is 0.25, and the content of copper silicate with a silicomall structure is 40%.

[0054] To avoid mutual interference between the XRD patterns of type A molecular sieves and malachite XRD patterns, Figure 1 These are X-ray diffraction patterns of a fresh sample (copper silicate with malachite structure) prepared under this patent, a sample after reduction with hydrogen (programmed temperature reduction, maximum temperature 230℃), and a sample after normal direct use for removing CO, O2, and sulfur from hydrogen. Among them: 1#: fresh material; 2#: material after hydrogen reduction; 3#: sample of fresh sample 1# after normal use for hydrogen purification in fuel cell vehicles for a period of time. Figure 1 The absorption peak lines of the chrysocolla standard card are also marked on it.

[0055] By comparing the X-ray diffraction pattern of the fresh sample #1 with the absorption peak positions of the malachite standard card, it can be confirmed that the copper silicate synthesized in this invention has a malachite structure.

[0056] The X-ray diffraction pattern of sample #1 shows a diffuse phase with no significant change in composition, indicating it is primarily an amorphous or microcrystalline substance. No Cu is present in the sample. 0 And Cu₂O. Sample #2 is the sample after hydrogen reduction, showing a strongest Cu₂O diffraction peak at 2θ = 36.5°; and a Cu₂O peak at 2θ = 43.3°. 0 The first strong diffraction peak appears at 2θ = 50.5 (°) with a Cu peak. 0 The second strongest diffraction peak is at 2θ = 36.5°, while the peak at 2θ = 62.5° is the Cu₂O diffraction peak. Sample #3's Cu₂O first strong diffraction peak at 2θ = 36.5° is stronger than that of sample #2, and its diffraction peak at 2θ = 62.5° is also stronger. Cu₂O at 2θ = 43.3°... 0 The diffraction peaks are weaker than those of sample #2, at 2θ = 50.5 (°) Cu 0The second strongest diffraction peak of the sample was weaker than that of sample #2. This indicates that there was a significant difference in the X-ray diffraction peaks of the hydrogen-reduced sample and the fresh sample #1 of this invention after they had been used for a period of time for hydrogen purification in fuel cell vehicles. This suggests that the purification material of this invention has a different mechanism for purifying CO and other gases in fuel cell vehicles compared to the mechanism for hydrogen reduction, and that the hydrogen purification material of this invention possesses unique catalytic purification characteristics.

[0057] Comparative Example 1:

[0058] 1 L of a 0.15 mol / L copper ammonia solution was prepared using copper chloride and urea. 1 L of a 0.4 mol / L silica sol solution was prepared using commercially available 20% silica sol. The solutions were then poured into a stirred container and stirred until homogeneous. The solution was evaporated to dryness using steam heating. The material was repeatedly washed with reverse osmosis purified water and then dried at 100°C. The material was then calcined at 450°C for 6 hours to obtain approximately 30 g of material I. 20 g of 5A molecular sieve was added and the material was ball-milled for 5 hours. The mixture was then sheeted to obtain approximately 50 g of purified material B1.

[0059] Comparative Example 2:

[0060] Prepare 1L of 0.15mol / L copper chloride solution, and prepare 1L of 0.4mol / L silica sol solution using commercially available 20% silica sol. Add the solutions to a container with a stirrer and stir until homogeneous. Add sodium carbonate solution to co-precipitate and obtain a precipitate. Wash the precipitate repeatedly with reverse osmosis purified water, dry the filtered material at 100℃, and then calcine at 400℃ for 6 hours to obtain ~36g of material I. Add 24g of 4A molecular sieve and ball mill for 5 hours, then sheet and shape to obtain ~60g of purified material B2.

[0061] The evaluation results of the seven samples prepared above in a typical volume composition of 99.98% H2, 70ppm O2, 8ppm CO, and 0.08ppm H2S (a typical gas source after industrial by-product hydrogen is purified by PSA) are shown in Table 1.

[0062] Table 1

[0063]

[0064]

[0065] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. The application of hydrogen purification materials in the simultaneous purification and removal of CO, O2 and sulfur impurities from hydrogen-containing source gases, wherein the hydrogen purification material is a composite of copper silicate with a chalcocite structure and type A molecular sieve, wherein the content of copper silicate with a chalcocite structure is 30-70%, and the balance is type A molecular sieve.

2. The application according to claim 1, characterized in that: The hydrogen purification material is prepared by co-precipitation, washing, drying and calcination of copper ammonia solution and silica sol to obtain copper silicate with a silicomallic structure, which is then compounded with type A molecular sieve and shaped.

3. The application according to claim 2, characterized in that: The molar ratio of CuO to SiO2 in the copper silicate with the malachite structure is 0.1~0.5:1; the calcination temperature is 350~400℃.

4. The application according to claim 1, characterized in that: The type A molecular sieve is a 3A, 4A, or 5A molecular sieve.

5. The application according to claim 1, characterized in that: The purification and removal temperature is 60~120℃.

6. The application according to claim 1, characterized in that: It is used in the purification of hydrogen for fuel cell vehicles, and at the same time, it removes CO, O2 and sulfur impurities from high-purity hydrogen to obtain hydrogen for fuel cell vehicles.

7. A method for preparing hydrogen purification materials, characterized in that: Includes the following steps: (1) Prepare 0.05~1.0mol / L copper ammonia solution and 0.1~1.0mol / L silica sol, and pour them into a container with a stirrer and stir evenly; (2) The above solution is evaporated by steam heating, and the evaporated material is repeatedly washed with reverse osmosis pure water. The filtered material is dried at 100~150℃ and then calcined at 350~400℃ for 3~6 hours to obtain copper silicate with malachite structure. (3) Add type A molecular sieves to copper silicate with malachite structure in proportion, ball mill, and form into sheets to obtain hydrogen purification material with malachite structure.

8. The preparation method according to claim 7, characterized in that: The copper ammonia solution is a solution generated by the reaction of copper salt and ammonia source substance, wherein the ammonia source substance is 1.5 to 2 times the theoretical amount.

9. The preparation method according to claim 8, characterized in that: The copper salt is selected from one or more of copper nitrate, copper acetate, and copper chloride, and the ammonia source is selected from one or more of ammonia water, urea, and ammonium bicarbonate.

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