A preparation method of a non-noble metal catalyst for dehydrogenation of organic hydrogen storage liquid to produce hydrogen

Abstract

This invention relates to the field of catalysts, and more particularly to a method for preparing a non-precious metal catalyst for dehydrogenation of organic hydrogen storage liquids. The method comprises the following steps: mixing tetraethyl silicate and an aqueous ethanol solution to obtain a mixed solution; mixing the mixed solution with a solution containing nickel and copper salts, and hydrolyzing the mixture to obtain a sol; adjusting the pH to ≥7 and reacting to obtain a slurry; evaporating and concentrating the slurry to obtain an intermediate; and sequentially drying and calcining the intermediate to obtain the non-precious metal catalyst. This invention uses a non-precious metal as the active component, avoiding the use of expensive precious metals, and the raw materials are inexpensive and readily available; the reaction process is a one-pot method, eliminating the need for complex operating procedures.

Description

Technical Field

[0001] This invention relates to the field of catalysts, and more particularly to a method for preparing a non-precious metal catalyst for dehydrogenation of organic hydrogen storage liquids to produce hydrogen. Background Technology

[0002] Hydrogen energy is considered an ideal energy carrier to replace fossil fuels, but its storage and transportation currently face certain challenges. Among various hydrogen storage technologies, Liquid Organic Hydrogen Carrier (LOHC) technology shows significant potential due to its efficient and stable storage and transportation characteristics. This technology is based on a reversible hydrogenation / dehydrogenation cycle between unsaturated organic compounds (such as benzene, toluene, and naphthalene) and their corresponding hydrogenation products (such as cyclohexane, methylcyclohexane, and decahydronaphthalene), thereby achieving the storage and release of hydrogen. For example, the decahydronaphthalene / naphthalene combination can achieve a hydrogen storage capacity of 7.3 wt% by mass density and a volume density of 64.8 kg-H2 / m³. 3 It has a large hydrogen storage capacity and can be transported at ambient temperature and pressure using methods similar to those used for transporting finished oil products, making it convenient and safe. The catalyst is the core of efficient dehydrogenation in LOHC hydrogen production; currently, most conventional catalysts use precious metals as the active component.

[0003] CN 120243087 A discloses a low-temperature dehydrogenation catalyst for organic hydrogen storage liquids, its preparation method, and its application. CN 115945209 A discloses a Ni@Pd core-shell nanocatalyst supported on KIT-6 molecular sieve for organic liquid hydrogen storage, its preparation method, and its application. CN 120394039 A discloses an organic liquid dehydrogenation catalyst prepared by impregnation method, using modified alumina as a support, Pt, Pd, and other noble metals as active components, and Fe and Co as auxiliary agents. CN 116803520 A discloses a mesoporous SiO2 supported palladium-ruthenium catalyst and its preparation method, which achieves uniform dispersion of noble metal components by means of electrostatic adsorption and glow discharge plasma reduction technology.

[0004] It can be seen that in existing literature, the dehydrogenation catalysts for liquid organic hydrogen storage supports such as decahydronaphthalene are mainly noble metal supported catalysts. However, they face problems such as high cost, insufficient resistance to poisoning, and insufficient resistance to sintering in practical industrial applications. Therefore, it is crucial to develop non-noble metal catalysts that combine high activity with economic feasibility. Summary of the Invention

[0005] This invention provides a method for preparing a non-precious metal catalyst for dehydrogenation of organic hydrogen storage liquids to produce hydrogen, which combines high activity with economic feasibility.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides a method for preparing a non-noble metal catalyst, comprising the following steps: Tetraethyl silicate and an aqueous ethanol solution were mixed to obtain a mixed solution; The mixed solution is mixed with a solution containing nickel and copper salts, and hydrolyzed to obtain a sol; then the pH is adjusted to ≥7, and a reaction is carried out to obtain a slurry; The slurry is evaporated and concentrated to obtain an intermediate; the intermediate is then dried and calcined to obtain a non-precious metal catalyst.

[0007] In some specific embodiments, the ratio of the tetraethyl silicate to the aqueous ethanol solution is (0.02~2) mol: 1L.

[0008] In some specific embodiments, the concentration of the ethanol aqueous solution is 10wt% to 60wt%.

[0009] In some specific embodiments, the molar amount of silicon in the tetraethyl silicate ethanol aqueous solution is a, and the total molar amount of nickel and copper in the solution containing nickel and copper salts is b, where a and b satisfy the condition: a:b = 0.5~5:1.

[0010] In some specific embodiments, the molar ratio of nickel to copper in the solution containing nickel and copper salts is (80~90):(10~20).

[0011] In some specific embodiments, the solution containing nickel and copper salts includes nickel nitrate and copper nitrate.

[0012] In some specific embodiments, the hydrolysis temperature is 0~60℃ and the hydrolysis time is 0.2~10h.

[0013] In some specific embodiments, the substance for adjusting the pH value includes at least one of NaOH solution, KOH solution, Na2CO3 solution, K2CO3 solution, and ammonia water.

[0014] In some specific embodiments, the pH value is 7 to 13.

[0015] In some specific embodiments, the reaction temperature is 0~60℃ and the reaction time is 1~96h.

[0016] In some specific embodiments, the evaporation and concentration temperature is 40~100℃, and the solid content of the intermediate is 10wt%~50wt%.

[0017] In some specific embodiments, the calcination temperature is 400~700℃, and the calcination time is 3~6h.

[0018] A second aspect of the present invention also provides a non-precious metal catalyst prepared by the above-described method for preparing a non-precious metal catalyst.

[0019] A third aspect of the present invention also provides the application of the above-mentioned non-precious metal catalyst in the dehydrogenation of organic hydrogen storage liquids to produce hydrogen.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention uses non-precious metals as the active component, avoiding the use of expensive precious metals, and the raw materials are inexpensive and readily available. The reaction process is a "one-pot" method, requiring no complicated operating procedures. The preparation method of this invention allows the active components Ni and Cu ions to be uniformly distributed in the silica hydrogel network, forming a well-dispersed NiCu-SiO2 catalyst, thereby promoting the dehydrogenation of LOHC such as decahydronaphthalene. Attached Figure Description

[0021] The above and other objects, features, and advantages of the invention will be apparent from the following description of preferred embodiments illustrating the gist of the invention and its use, and the accompanying drawings, in which: Figure 1 This is a transmission electron microscope (TEM) image of the non-precious metal catalyst prepared in Example 1. Detailed Implementation

[0022] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments described below are for illustrative purposes only and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the following embodiments, conditions and methods known in the art can be used for processing.

[0023] This invention provides a method for preparing a non-noble metal catalyst, comprising the following steps: Tetraethyl silicate and an aqueous ethanol solution were mixed to obtain a mixed solution; The mixed solution is mixed with a solution containing nickel and copper salts, and hydrolyzed to obtain a sol; then the pH is adjusted to ≥7, and a reaction is carried out to obtain a slurry; The slurry was evaporated and concentrated to obtain an intermediate; the intermediate was then dried and calcined to obtain a non-precious metal catalyst, denoted as NiCu-SiO2 catalyst.

[0024] The method for preparing non-precious metal catalysts provided by this invention involves preparing a catalyst by reacting tetraethyl silicate with nickel and copper salts via a sol-gel method. By controlling the hydrolysis, gelation, and metal ion complexation processes of tetraethyl silicate, a highly efficient dehydrogenation catalyst with a large specific surface area and uniform metal dispersion is prepared.

[0025] In some embodiments, the ratio of tetraethyl silicate to the aqueous ethanol solution is (0.02~2) mol:1L. As examples, the ratio of tetraethyl silicate to the aqueous ethanol solution can be 0.02 mol:1L, 0.08 mol:1L, 0.1 mol:1L, 0.2 mol:1L, 0.5 mol:1L, 1 mol:1L, 1.2 mol:1L, 1.5 mol:1L, and 2 mol:1L, etc.

[0026] In some embodiments, the concentration of the ethanol aqueous solution is 10 wt% to 60 wt%. As an example, the concentration of the ethanol aqueous solution in the tetraethyl silicate ethanol aqueous solution can be 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, and 60 wt%, etc.

[0027] In some embodiments, the molar amount of silicon in the tetraethyl orthosilicate ethanol aqueous solution is 'a', and the total molar amount of nickel and copper in the solution containing nickel and copper salts is 'b', where a and b satisfy the ratio a:b = 0.5 to 5:1. For example, a:b can be 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, and 5:1, etc.

[0028] In this invention, adjusting the ratio of a to b within the aforementioned range helps to improve catalyst performance. If a is too large, it will result in less catalytically active material and a larger catalyst dosage; if b is too large, it will lead to uneven metal dispersion.

[0029] In some embodiments, the molar ratio of nickel to copper in the solution containing nickel and copper salts is (80-90):(10-20). As examples, the molar ratio of nickel to copper in the solution containing nickel and copper salts can be 80:20, 82:18, 85:15, 88:10, and 90:10, etc.

[0030] In this invention, adjusting the molar ratio of nickel and copper within the aforementioned range helps to improve catalytic performance. Excessive nickel content leads to insufficient promoting effect of the promoter; excessive copper content results in too low a content of the main catalyst component.

[0031] In some embodiments, the solution containing nickel and copper salts includes nickel nitrate and copper nitrate.

[0032] In some embodiments, the hydrolysis temperature is 0~60℃, and the hydrolysis time is 0.2~10h. As an example, the hydrolysis temperature can be 0℃, 10℃, 20℃, 30℃, 40℃, 50℃, and 60℃, etc., and the hydrolysis time can be 0.2h, 2h, 4h, 5h, 8h, and 10h, etc.

[0033] In this invention, by controlling the hydrolysis temperature and time within the aforementioned range, it is beneficial to form a suitable amount and dispersion of silica sol. If the hydrolysis temperature is too high or the time is too long, the amount of silica sol will be too large and the reaction will be too fast; if the hydrolysis temperature is too low or the time is too short, the amount of silica sol will be insufficient and the reaction will be incomplete.

[0034] In some embodiments, the substance for adjusting the pH value includes at least one of NaOH solution, KOH solution, Na2CO3 solution, K2CO3 solution, and ammonia water.

[0035] In some embodiments, the pH value is 7 to 13. As an example, the pH value can be 7, 8, 9, 10, 11, 12, and 13, etc.

[0036] In this invention, by adjusting the pH value within the above range, it is helpful for the metal to form a stable complex and promotes a suitable gelation reaction rate.

[0037] In some embodiments, the reaction temperature is 0~60°C, and the reaction time is 1~96h. As an example, the reaction temperature can be 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, and 60°C, etc., and the reaction time can be 1h, 2h, 4h, 8h, 12h, 24h, 36h, 48h, and 96h, etc.

[0038] In this invention, gelation and metal ion complexation reactions occur during the reaction process. By controlling the reaction temperature and time within the aforementioned range, it is helpful to form a gel network of suitable size. If the reaction temperature is too high or the reaction time is too long, the reaction will be too fast, resulting in an over-reaction and an oversized, uneven network. If the reaction temperature is too low or the reaction time is too short, the reaction will be too slow and insufficient, resulting in an undersized, uneven network.

[0039] In some embodiments, the evaporation and concentration temperature is 40~100°C, and the solid content of the intermediate is 10wt%~50wt%. As an example, the evaporation and concentration temperature can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C, etc., and the solid content of the intermediate can be 10wt%, 20wt%, 30wt%, 40wt%, and 50wt%, etc.

[0040] In this invention, the slurry is first evaporated and concentrated to make it into a paste, so as to control the water content and solid content in the paste.

[0041] In some embodiments, the calcination temperature is 400~700℃, and the calcination time is 3~6h. As examples, the calcination temperature can be 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, and 700℃, etc., and the calcination time can be 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, and 6h, etc.

[0042] In some embodiments, the heating rate during calcination is 2~5℃ / min. As examples, the heating rate during calcination can be 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min, and 5℃ / min, etc.

[0043] A second aspect of the present invention also provides a non-precious metal catalyst prepared by the above-described method for preparing a non-precious metal catalyst.

[0044] A third aspect of the present invention also provides the application of the above-mentioned non-precious metal catalyst in the dehydrogenation of organic hydrogen storage liquids to produce hydrogen.

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Example 1 Solution A was prepared by dissolving 4.94 g Ni(NO3)2·6H2O and 0.72 g Cu(NO3)2·3H2O in 50 mL of deionized water. Solution B was prepared by dissolving 16.64 g tetraethyl orthosilicate (TEOS) in 50 mL of 60 wt% ethanol aqueous solution. Both solutions were stirred separately at room temperature for 1 h and then mixed to obtain solution C. Solution C was hydrolyzed by magnetic stirring at 25 °C for 2 h to form a sol. 10% NH3·H2O solution was slowly added to the sol to adjust the pH to 10. The reaction was stirred at 25 °C for 1 h, then the temperature was raised to 80 °C, and the mixture was continuously stirred and evaporated until the solid content reached 30 wt%. The sol was then naturally cooled to room temperature. After freeze-drying, the sample was transferred to a muffle furnace and heated to 550 °C at a rate of 3 °C / min. The sample was then calcined at this temperature for 4 h to obtain a non-precious metal catalyst.

[0047] Transmission electron microscopy (TEM) images of the non-noble metal catalyst prepared in Example 1 are shown below. Figure 1 As shown. By Figure 1It can be seen that the metal particles in this non-precious metal catalyst are uniformly dispersed on the silicon substrate, with no obvious agglomeration.

[0048] Example 2 The difference from Example 1 is that the hydrolysis time is 1 hour and the reaction time is 72 hours.

[0049] Comparative Example 1 Using commercially available silica sol at a concentration of 30%, nickel nitrate and copper nitrate solutions were added in the same proportion as described above. The solution was titrated with 1 mol / L Na2CO3 solution to prepare a NiCu-SiO2 catalyst with the same composition as in Example 1 by co-precipitation.

[0050] Performance testing 150 mg of the catalyst from Examples 1-2 and Comparative Example 1 was packed into a stainless steel reaction tube with an inner diameter of 8 mm, and reduced at 350 °C for 2 h with hydrogen gas at a flow rate of 30 mL / min. After reduction, the gas was switched to N2 and H2 (50% by volume) at a flow rate of 30 mL / min as carrier gas and to provide a reducing atmosphere protection. The reactant decahydronaphthalene was introduced at a rate of 0.5 mL / h, and the reaction was carried out at atmospheric pressure for 2 h. The catalytic effect is shown in Table 1.

[0051] Table 1. Catalytic effects of the catalysts in Examples 1-2 and Comparative Example 1

[0052] As shown in Table 1, in the process of preparing NiCu-SiO2 catalyst by sol-gel method, the physicochemical properties of the catalyst can be significantly changed by controlling the hydrolysis time, reaction conditions, pH of the reaction system and aging time, so that the active components Ni and Cu ions are uniformly distributed in the silica hydrogel network, forming a NiCu-SiO2 catalyst with good dispersion effect, which in turn affects the dehydrogenation and hydrogen production effect of LOHC such as decahydronaphthalene.

[0053] Although preferred embodiments of the invention have been shown and described, it is conceivable that those skilled in the art can devise various modifications to the invention within the spirit and scope of the appended claims.

Claims

1. A method for preparing a non-precious metal catalyst, characterized in that, Includes the following steps: Tetraethyl silicate and an aqueous ethanol solution were mixed to obtain a mixed solution; The mixed solution is mixed with a solution containing nickel and copper salts, and hydrolyzed to obtain a sol; then the pH is adjusted to ≥7, and a reaction is carried out to obtain a slurry; The slurry was evaporated and concentrated to obtain an intermediate. The intermediate was successively dried and calcined to obtain a non-precious metal catalyst.

2. The method for preparing the non-noble metal catalyst according to claim 1, characterized in that, The ratio of the amount of tetraethyl silicate to the amount of ethanol aqueous solution is (0.02~2) mol: 1 L; The concentration of the ethanol aqueous solution is 10wt%~60wt%.

3. The method for preparing the non-noble metal catalyst according to claim 1, characterized in that, The molar amount of silicon in the ethanol aqueous solution of the tetraethyl silicate is a, and the total molar amount of nickel and copper in the solution containing nickel and copper salts is b, where a and b satisfy: a:b = 0.5~5:

1. The molar ratio of nickel to copper in the solution containing nickel and copper salts is (80~90):(10~20). The solution containing nickel and copper salts includes nickel nitrate and copper nitrate.

4. The method for preparing the non-precious metal catalyst according to claim 1, characterized in that, The hydrolysis temperature is 0~60℃, and the hydrolysis time is 0.2~10h.

5. The method for preparing the non-noble metal catalyst according to claim 1, characterized in that, The pH-adjusting substance includes at least one of NaOH solution, KOH solution, Na2CO3 solution, K2CO3 solution, and ammonia water; The pH value is 7~13.

6. The method for preparing the non-noble metal catalyst according to claim 1, characterized in that, The reaction temperature is 0~60℃, and the reaction time is 1~96h.

7. The method for preparing the non-noble metal catalyst according to claim 1, characterized in that, The evaporation and concentration temperature is 40~100℃, and the solid content of the intermediate is 10wt%~50wt%.

8. The method for preparing the non-noble metal catalyst according to claim 1, characterized in that, The calcination temperature is 400~700℃, and the calcination time is 3~6h.

9. A non-precious metal catalyst prepared by the method of any one of claims 1 to 8.

10. The application of the non-precious metal catalyst according to claim 9 in the dehydrogenation of organic hydrogen storage liquids to produce hydrogen.

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