Supported cobalt-based quaternary catalyst as well as preparation method and application thereof

Abstract

The invention discloses a supported cobalt-based quaternary catalyst as well as a preparation method and application thereof, and belongs to the technical field of hydrogen production through hydrolysis of sodium borohydride. The supported cobalt-based quaternary catalyst is composed of a carrier material and Co, W, B and P which are jointly supported on the carrier material, and can be prepared through a simple chemical plating method. The structure of the supported cobalt-based quaternary catalyst provided by the invention is a rough and irregular aggregate, and the supported cobalt-based quaternary catalyst is large in specific surface area, high in catalytic performance and relatively high in catalytic activity on a hydrolysis reaction of sodium borohydride. The supported cobalt-based quaternary catalyst provided by the invention is simple in preparation method, low in cost and wide in raw material source.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production by hydrolysis of sodium borohydride, and specifically relates to a supported cobalt-based quaternary catalyst and a preparation method and application thereof. Background Art

[0002] Hydrogen is a clean alternative to natural gas. Hydrogen is the most abundant chemical element, accounting for an estimated 75% of the mass of the universe. However, hydrogen as a gas is very scarce. Hydrogen can be produced from a variety of sources, such as natural gas, nuclear power, biogas, and renewable energy such as solar and wind power. The challenge is to harness hydrogen on a large scale to fuel our homes and businesses.

[0003] As a hydrogen storage material, sodium borohydride can spontaneously react with water to produce high-purity hydrogen, but its disadvantage is that the reaction rate is slow and the conversion rate is only 7-8%. Precious metal catalysts such as palladium, ruthenium, and platinum have high catalytic performance for the hydrolysis of sodium borohydride to produce hydrogen, but they are expensive and not suitable for widespread application.

[0004] Therefore, it is of great significance to develop high-performance and low-cost catalysts for hydrogen production by hydrolysis of sodium borohydride. Summary of the invention

[0005] The purpose of the present invention is to provide a supported cobalt-based four-way catalyst and a preparation method and application thereof. By further doping W and P on the Co-B-based catalyst, a catalyst that can replace precious metals is obtained.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a supported cobalt-based four-way catalyst, which is composed of a support material and Co, W, B and P that are jointly supported on the support material.

[0008] The quaternary material of Co, W, B and P on the carrier material is an amorphous structure; Co is electron-rich and exists mainly in elemental state and oxidation state, while W, B and P are electron-deficient and exist mainly in oxidation state.

[0009] Compared with the Co-B-based catalyst, the Co-WBP-based catalyst of the present invention has the following advantages: the doping of W can make Co obtain electrons, so that the binding energy of the Co element moves to a low binding energy, the electron cloud density increases, and the active sites with high electron density can promote the hydrolysis of sodium borohydride; the doping of the P element not only changes the electron cloud density of Co, but also changes the specific surface area and pore size of the catalyst. In the present invention, Co, W, B, and P act synergistically to form a Co-WBP-based catalyst with high catalytic activity.

[0010] Optionally, the carrier material includes nickel foam (NF), copper foam, etc.

[0011] The second technical solution of the present invention is to provide a method for preparing the above-mentioned supported cobalt-based four-way catalyst, wherein Co, W, B and P are loaded on a carrier material by chemical plating.

[0012] Preferably, the chemical plating further includes washing and drying steps.

[0013] Preferably, the chemical plating further includes a calcination step.

[0014] The invention calcines the supported cobalt-based quaternary catalyst after chemical plating, so as to further improve the rate of catalyzing the hydrolysis of sodium borohydride to produce hydrogen.

[0015] More preferably, the calcination temperature is 300°C.

[0016] Preferably, the specific steps of the chemical plating include:

[0017] (1) preparing a solution A containing a Co source, a W source and a P source, immersing a support material in the solution A, then adding an alkaline sodium borohydride solution for reduction, and taking out the support material;

[0018] (2) Repeat or not repeat step (1) to complete chemical plating.

[0019] More preferably, the step (1) is repeated twice.

[0020] The present invention can obtain a catalyst with better catalytic performance by multiple chemical plating. However, the catalytic performance of the catalyst is limited after three chemical plating. Therefore, it is preferred that the number of repeated chemical plating is 2 times.

[0021] More preferably, in step (1), the Co source is CoCl2·6H2O; the W source is Na2WO4·2H2O; and the P source is NaH2PO2.

[0022] Further preferably, the mass ratio of CoCl2·6H2O, Na2WO4·2H2O and NaH2PO2 is 10:1:10.

[0023] More preferably, the solution A further comprises a plating aid.

[0024] Optionally, the plating assistant is ammonium chloride and ammonia water.

[0025] More preferably, the ratio of the molar amount of NaBH4 in the alkaline sodium borohydride solution to the total molar amount of Co and W in the solution A is not less than 1:1.375.

[0026] The above molar ratio is required to ensure that the metal salt ions are completely reduced.

[0027] The third technical solution of the present invention is to provide an application of the above-mentioned supported cobalt-based quaternary catalyst in catalyzing the hydrolysis of sodium borohydride to produce hydrogen.

[0028] The beneficial technical effects of the present invention are as follows:

[0029] (1) The structure of the supported cobalt-based four-way catalyst provided by the present invention is a rough and irregular aggregate with a large specific surface area.

[0030] (2) The preparation method of the supported cobalt-based four-way catalyst provided by the present invention is simple, low-cost, and has a wide range of raw material sources.

[0031] (3) The supported cobalt-based quaternary catalyst provided by the present invention has high catalytic performance and high catalytic activity for the hydrolysis reaction of sodium borohydride. When used to catalyze the hydrolysis of sodium borohydride to produce hydrogen, the hydrogen production rate provided at 30°C can reach 400 mL·cm -2 ·min -1 , the hydrogen production is 100% of the theoretical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 (a) is the SEM image of Co-WBP / NF prepared in Example 5, (b) is the SEM image of Co-WB / NF prepared in Comparative Example 1, (c) is the SEM image of Co-BP / NF prepared in Comparative Example 2, (d) to (h) are the TEM image of Co-WBP / NF prepared in Example 5, the elemental mapping of P, the elemental mapping of W, the elemental mapping of Co, and the elemental mapping of B, respectively.

[0033] Figure 2 The rate of producing hydrogen by hydrolysis of sodium borohydride catalyzed by Co-WBP / NF prepared in Examples 1-5.

[0034] Figure 3 The catalytic performance of the Co-WBP / NF prepared in Example 5 after calcination at different temperatures for catalyzing the hydrolysis of sodium borohydride to produce hydrogen, wherein (a) is the relationship between the time for catalyzing the hydrolysis of sodium borohydride and the volume of hydrogen produced by Co-WBP / NF calcined at different temperatures, and (b) is the corresponding hydrogen production rate of Co-WBP / NF calcined at different temperatures.

[0035] Figure 4 The catalytic performance of Co-WBP / NF prepared in Example 5 for catalyzing the hydrolysis of sodium borohydride to produce hydrogen at different NaBH4 concentrations, wherein (a) is the relationship between the catalytic hydrolysis of sodium borohydride hydrogen production time and the hydrogen production volume, and (b) is the corresponding hydrogen production rate.

[0036] Figure 5The catalytic performance of Co-WBP / NF prepared in Example 5 for catalyzing the hydrolysis of sodium borohydride to produce hydrogen at different NaOH concentrations, wherein (a) is the relationship between the catalytic hydrolysis of sodium borohydride hydrogen production time and the hydrogen production volume, and (b) is the corresponding hydrogen production rate.

[0037] Figure 6 The catalytic performance of Co-WBP / NF prepared in Example 5, Co-WB / NF prepared in Comparative Example 1 and Co-BP / NF prepared in Comparative Example 2 for catalyzing the hydrolysis of sodium borohydride to produce hydrogen, wherein (a) is the relationship between the hydrogen production time and the hydrogen production volume of sodium borohydride hydrolysis catalyzed by different catalysts, and (b) is the hydrogen production rate corresponding to different catalysts.

[0038] Figure 7 The catalytic performance of Co-WBP / NF prepared in Example 5 for catalyzing the hydrolysis of sodium borohydride to produce hydrogen at different temperatures, wherein (a) is the relationship between the catalytic hydrolysis of sodium borohydride to produce hydrogen time and the hydrogen production volume, and (b) is the corresponding hydrogen production rate.

[0039] Figure 8 The cyclic performance of the Co-WBP / NF prepared in Example 5 for catalyzing the hydrolysis of sodium borohydride to produce hydrogen, including (a) the relationship between the immersion time of Co-WBP / NF for catalyzing the hydrolysis of sodium borohydride and the hydrogen production volume, and (b) the hydrogen production rate of Co-WBP / NF for catalyzing the hydrolysis of sodium borohydride for different immersion times. DETAILED DESCRIPTION

[0040] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0041] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0042] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0043] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0044] The ammonia water used in the embodiment of the present invention is commercially available ammonia water with a concentration of 25-28 wt %.

[0045] Example 1

[0046] Preparation of Co-WBP / NF:

[0047] (1) Clean the NF (1 cm × 1 cm × 2 mm) by ultrasonication in ethanol for 10 min, and then immerse in 10 wt % HCl solution and stir for 1 min to complete the NF pretreatment;

[0048] (2) Weigh 2.5 g CoCl2·6H2O, 0.25 g Na2WO4·2H2O, 4 g NH4Cl, 2.25 g ammonia water and 2.5 g NaH2PO2 and dissolve them in 50 mL deionized water to form solution A;

[0049] (3) Weigh 2 g of NaBH4 and 0.5 g of NaOH and dissolve them in 50 mL of deionized water to form solution B;

[0050] (4) Place the pretreated NF into 10 mL of solution A and heat at 25 °C;

[0051] (5) 10 mL of solution B was added dropwise into solution A containing NF to chemically reduce the solution until the generation of bubbles stopped, and the NF was removed;

[0052] (6) After chemical plating, the NF was washed alternately with deionized water and anhydrous ethanol for three times and then vacuum dried at 80°C for 8 h to obtain the supported catalyst Co-WBP / NF.

[0053] Example 2

[0054] Preparation of Co-WBP / NF:

[0055] Compared with Example 1, the only difference is that (4) and (5) are repeated once.

[0056] Example 3

[0057] Preparation of Co-WBP / NF:

[0058] Compared with Example 1, the only difference is that (4) and (5) are repeated twice.

[0059] Example 4

[0060] Preparation of Co-WBP / NF:

[0061] Compared with Example 1, the only difference is that (4) and (5) are repeated 3 times.

[0062] Example 5

[0063] Preparation of Co-WBP / NF:

[0064] Compared with Example 1, the only difference is that (4) and (5) are repeated 4 times.

[0065] Comparative Example 1

[0066] Preparation of Co-WB / NF:

[0067] Compared with Example 5, the only difference is that NaH2PO2 in solution A is omitted.

[0068] Comparative Example 2

[0069] Preparation of Co-BP / NF:

[0070] Compared with Example 5, the only difference is that Na2WO4·2H2O in solution A is omitted.

[0071] Figure 1 (a) is the SEM image of Co-WBP / NF prepared in Example 5, (b) is the SEM image of Co-WB / NF prepared in Comparative Example 1, (c) is the SEM image of Co-BP / NF prepared in Comparative Example 2, (d) to (h) are the TEM image of Co-WBP / NF prepared in Example 5, the elemental mapping of P, the elemental mapping of W, the elemental mapping of Co, and the elemental mapping of B, respectively.

[0072] Hydrogen production by catalyzing sodium borohydride hydrolysis using Co-WBP / NF prepared in Example 1-5:

[0073] Using alkaline sodium borohydride aqueous solution as raw material, the concentration of NaBH4 and NaOH is 10wt%. The raw material (5mL) and different Co-WBP / NF are placed in a reactor, and the temperature is kept constant at 30°C. The catalyst is tested. The rate of hydrogen production by sodium borohydride hydrolysis catalyzed by each catalyst is shown in Figure 2. Figure 2 , the number of chemical plating times on the vertical axis corresponds to different catalysts.

[0074] Figure 2 The results show that the rate of hydrogen production by catalytic hydrolysis of sodium borohydride by Co-WBP / NF prepared in Example 1 is 53 mL·g cat -1 ·min -1 The rate of hydrogen production by catalytic hydrolysis of sodium borohydride by Co-WBP / NF prepared in Example 2 under this condition was 175 mL·g cat-1 ·min -1 The rate of hydrogen production by catalytic hydrolysis of sodium borohydride by Co-WBP / NF prepared in Example 3 under this condition was 300 mL·g cat -1 ·min -1 The rate of hydrogen production by catalytic hydrolysis of sodium borohydride by Co-WBP / NF prepared in Example 4 under this condition was 340 mL·g cat -1 ·min -1 The rate of hydrogen production by catalytic hydrolysis of sodium borohydride by Co-WBP / NF prepared in Example 5 was 350 mL·g cat -1 ·min -1 .

[0075] The Co-WBP / NF prepared in Example 5 was calcined at 100°C, 200°C, 300°C, 400°C and 500°C (calcination time was 2 hours) and then used to catalyze the hydrolysis of sodium borohydride to produce hydrogen. The test conditions were: NaOH concentration was 10wt%, NaBH4 concentration was 10wt%, temperature was 30°C, and the volume of alkaline sodium borohydride aqueous solution was 5mL. The catalytic performance was shown in Table 1. Figure 3 , where (a) is the relationship between the hydrogen production time and hydrogen production volume of Co-WBP / NF calcined at different temperatures by catalyzing sodium borohydride hydrolysis, and (b) is the hydrogen production rate corresponding to Co-WBP / NF calcined at different temperatures (measured in terms of the hydrogen production rate in the first minute).

[0076] Figure 3 It shows that the catalytic performance of Co-WBP / NF calcined at 300℃ is the best.

[0077] The Co-WBP / NF prepared in Example 5 catalyzed the hydrolysis of sodium borohydride to produce hydrogen at different NaBH4 concentrations (5wt%, 10wt%, 15wt%, 20wt% and 25wt%). The test conditions were: NaOH concentration of 10wt%, temperature of 30°C, and volume of alkaline sodium borohydride aqueous solution of 5mL. The catalytic performance was shown in Table 5. Figure 4 , where (a) is the relationship between the hydrogen production time and the hydrogen production volume by catalytic hydrolysis of sodium borohydride, and (b) is the corresponding hydrogen production rate (measured in terms of the hydrogen production rate in the first minute).

[0078] Figure 4 The results show that when the concentration of NaBH4 is 20wt%, the rate of hydrogen production by sodium borohydride hydrolysis catalyzed by Co-WBP / NF is the highest, which is 510mL·cm -2 ·min -1 .

[0079] The Co-WBP / NF prepared in Example 5 catalyzed the hydrolysis of sodium borohydride to produce hydrogen at different NaOH concentrations (5wt%, 10wt%, 15wt% and 20wt%). The test conditions were: NaBH4 concentration was 10wt%, temperature was 30°C, and the volume of alkaline sodium borohydride aqueous solution was 5mL. The catalytic performance was shown in Table 5. Figure 5 , where (a) is the relationship between the hydrogen production time and the hydrogen production volume by catalytic hydrolysis of sodium borohydride, and (b) is the corresponding hydrogen production rate (measured in terms of the hydrogen production rate in the first minute).

[0080] Figure 5 The results show that when the NaOH concentration is 10wt%, the rate of hydrogen production by sodium borohydride hydrolysis catalyzed by Co-WBP / NF is the highest, which is 400mL·cm -2 ·min -1 .

[0081] The performance of Co-WBP / NF prepared in Example 5, Co-WB / NF prepared in Comparative Example 1 and Co-BP / NF prepared in Comparative Example 2 in catalyzing the hydrolysis of sodium borohydride to produce hydrogen was compared. The test conditions were: NaBH4 concentration was 10wt.%, NaOH concentration was 10wt.%, temperature was 30°C, the volume of alkaline sodium borohydride aqueous solution was 5mL, and the catalytic performance was shown in Table 1. Figure 6 , where (a) is the relationship between the hydrogen production time and hydrogen production volume of sodium borohydride hydrolysis catalyzed by different catalysts, and (b) is the hydrogen production rate corresponding to different catalysts (measured in the hydrogen production rate in the first minute).

[0082] Figure 6 It shows that the catalytic performance of each catalyst is Co-WBP / NF>Co-BP / NF>Co-WB / NF.

[0083] The Co-WBP / NF prepared in Example 5 catalyzed the hydrolysis of sodium borohydride to produce hydrogen at different temperatures (25°C, 30°C, 35°C and 40°C, respectively). The test conditions were: NaOH concentration was 10wt%, NaBH4 concentration was 10wt%, and the volume of alkaline sodium borohydride aqueous solution was 5mL. The catalytic performance was shown in Table 5. Figure 7 , where (a) is the relationship between the hydrogen production time and the hydrogen production volume by catalytic hydrolysis of sodium borohydride, and (b) is the corresponding hydrogen production rate (measured in terms of the hydrogen production rate in the first minute).

[0084] Figure 7 The results show that the rate of hydrogen production from sodium borohydride hydrolysis catalyzed by Co-WBP / NF increases with the temperature, reaching 390 mL·cm at 40 °C. -2 ·min -1 .

[0085] The cyclic performance of the Co-WBP / NF prepared in Example 5 for catalyzing the hydrolysis of sodium borohydride to produce hydrogen was tested. The Co-WBP / NF was placed in a large amount of alkaline sodium borohydride aqueous solution, taken out at different time points, and then its catalytic performance was tested (after each test, it was continued to be immersed in the alkaline sodium borohydride aqueous solution). The test conditions were: NaBH4 concentration of 20wt.%, NaOH concentration of 10wt.%, temperature of 30°C, alkaline sodium borohydride aqueous solution volume of 5mL, and the cyclic performance was shown in Table 1. Figure 8 , where (a) the relationship between the time and volume of hydrogen produced by the hydrolysis of sodium borohydride catalyzed by Co-WBP / NF immersed for different times and (b) the hydrogen production rate (measured in the hydrogen production rate in the first minute) of the hydrolysis of sodium borohydride catalyzed by Co-WBP / NF immersed for different times.

[0086] Figure 8 The results show that the catalytic performance of Co-WBP / NF in Example 5 is still 360 mL·cm after being immersed in an alkaline sodium borohydride aqueous solution for 50 hours. -2 ·min -1 , still has 70.59% of the initial performance.

[0087] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A supported cobalt-based four-way catalyst, characterized in that: The invention is composed of a support material and Co, W, B and P which are jointly supported on the support material.

2. A method for preparing the supported cobalt-based four-way catalyst according to claim 1, characterized in that: Co, W, B and P were loaded on the support material by chemical plating.

3. The preparation method according to claim 2, characterized in that: The chemical plating process also includes washing and drying steps.

4. The preparation method according to claim 2, characterized in that: The method further comprises a calcination step after the chemical plating.

5. The preparation method according to claim 2, characterized in that: The specific steps of the chemical plating include: (1) preparing a solution A containing a Co source, a W source and a P source, immersing a support material in the solution A, then adding an alkaline sodium borohydride solution for reduction, and taking out the support material; (2) Repeat or not repeat step (1) to complete chemical plating.

6. The preparation method according to claim 5, characterized in that: The step (1) is repeated twice.

7. The preparation method according to claim 5, characterized in that: In step (1), the Co source is CoCl2·6H2O; the W source is Na2WO4·2H2O; and the P source is NaH2PO2.

8. The preparation method according to claim 7, characterized in that: The mass ratio of the CoCl2·6H2O, Na2WO4·2H2O and NaH2PO2 is 10:1:

10.

9. The preparation method according to claim 5, characterized in that: The ratio of the molar amount of NaBH4 in the alkaline sodium borohydride solution to the total molar amount of Co and W in the solution A is not less than 1:1.

375.

10. Use of the supported cobalt-based quaternary catalyst according to claim 1 in catalyzing the hydrolysis of sodium borohydride to produce hydrogen.

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