A NiWC catalyst for low-temperature H2 catalysis and its preparation method

Abstract

This invention discloses a NiWC catalyst for low-temperature H2 catalysis and its preparation method, relating to the field of novel hydrogen combustion catalyst synthesis. The preparation process includes the following steps: soaking activated carbon in 20 ml of deionized water; adding a certain amount of (NH4)6W7O 24 Ni(NO3)2·6H2O and Ni(NO3)2·6H2O were added to deionized water soaked with activated carbon, stirred, and sonicated. The resulting solution was placed in an oven and dried at 90°C. The dried solid was then heated in nitrogen at a rate of 1–5°C / min from 20°C to 700°C for 1 hour. Then, it was heated in H2 / CH4 at a rate of 1–2°C / min from 700°C to 900°C for 2 hours to obtain the NiWC catalyst. The NiWC catalyst prepared by this invention exhibits catalytic activity close to that of noble metals such as Pt / Pd at the same reaction temperature, and has a significant advantage in preparation cost.

Description

Technical Field

[0001] This invention relates to the field of novel hydrogen combustion catalyst synthesis, specifically to a NiWC catalyst for low-temperature H2 catalysis and its preparation method. Background Technology

[0002] Hydrogen is a flammable gas and a clean energy source. Our research on hydrogen reactions, especially its further study on low-temperature catalytic reactions, is of great significance to the future energy field. For example, low-temperature reactions that convert chemical energy into electrical energy will help the further development of new energy batteries. Furthermore, nuclear power plant reactors produce or leak a certain amount of hydrogen. If this hydrogen is not depleted quickly, the accumulated hydrogen concentration can easily lead to an explosion, causing a serious nuclear accident. Low-temperature catalytic combustion of H2 is beneficial for nuclear power plants to deplete hydrogen under low-energy operating conditions, ensuring the safety of nuclear power plants.

[0003] Currently, low-temperature catalytic combustion of H2 is a popular research area, mentioned in numerous scientific papers. However, these studies generally use noble metals such as Pt / Pd as the main active materials, while non-noble metals typically exhibit lower catalytic activity. This is especially true in the field of low-temperature H2 catalysis, where catalysts using non-noble metals as the main active material are almost nonexistent. Therefore, high catalyst costs are a widely accepted issue in the field of low-temperature H2 catalysis. Further reducing catalyst costs is crucial for the widespread adoption of low-temperature H2 catalytic reactions. Summary of the Invention

[0004] The present invention aims to provide a NiWC catalyst for low-temperature H2 catalysis and its preparation method, so as to solve the technical problem of high cost of existing catalysts for low-temperature H2 catalytic reactions.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a NiWC catalyst for low-temperature H2 catalysis includes the following steps:

[0007] (1) Soak activated carbon in 20 ml of deionized water;

[0008] (2) A certain amount of (NH4)6W7O 24 ·6H2O and Ni(NO3)2·6H2O were added to deionized water soaked with activated carbon, stirred and sonicated;

[0009] (3) Place the solution obtained in step (2) into an oven and dry it at 90°C;

[0010] (4) The solid obtained after drying is heated from 20°C to 700°C in nitrogen at a heating rate of 1-5°C / min for 1 h; then heated from 700°C to 900°C in H2 / CH4 at a heating rate of 1-2°C / min for 2 h to obtain the NiWC catalyst.

[0011] Furthermore, in step (2), the Ni:W molar ratio is 1:2 to 1:3.

[0012] Furthermore, in step (4), when the solid is in nitrogen, the temperature is increased from 20°C to 700°C at a rate of 5°C / min.

[0013] Furthermore, the nitrogen gas is a nitrogen flow rate of 100 ml / min.

[0014] Furthermore, when the solid is in H2 / CH4, the temperature is increased from 700℃ to 900℃ at a heating rate of 2℃ / min.

[0015] More preferably, the volume ratio of H2 / CH4 is 4:1, and the flow rate is 100 ml / min.

[0016] The NiWC catalyst prepared by any of the above methods.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The NiWC catalyst prepared by this invention has high catalytic activity for hydrogen catalytic reaction at low temperature (80-100℃).

[0019] 2. The NiWC catalyst prepared by this invention has catalytic activity close to that of noble metals such as Pt / Pd at the same reaction temperature, and has a significant advantage in preparation cost. Attached Figure Description

[0020] Figure 1 TEM image of the NiWC catalyst prepared in Example 2;

[0021] Figure 2 Line graphs showing hydrogen conversion rate versus reaction temperature for NiWC catalysts with different Ni:W ratios;

[0022] Figure 3 The hydrogen conversion rate versus reaction temperature is a line graph for NiWC catalysts prepared with different active components.

[0023] Figure 4 A bar chart showing the effect of different heating rates on the hydrogen conversion rate at 100℃ in the first heating program.

[0024] Figure 5The bar chart shows the effect of different heating rates on the hydrogen conversion rate at 100℃ in the second heating program. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described below in conjunction with various embodiments and accompanying drawings. The implementation of the present invention includes, but is not limited to, the following embodiments.

[0026] Example 1

[0027] 1g of activated charcoal was soaked in 20ml of deionized water. Then 10.3g of (NH4)6W7O was added. 24 ·6H2O and 2.4 g of Ni(NO3)2·6H2O were added to the above solution, stirred for 10 min, and then sonicated for 4 h. The solution was then placed in an oven and dried at 90 °C. The dried solid was then heated from 20 °C to 700 °C at a rate of 5 °C / min in a nitrogen stream of 100 ml / min for 1 h; finally, it was heated from 700 °C to 900 °C at a rate of 2 °C / min in a stream of H2 of 80 ml / min and CH4 of 20 ml / min for 2 h to obtain Ni. 0.1 W 0.1 C catalyst.

[0028] Example 2

[0029] 1g of activated charcoal was soaked in 20ml of deionized water. Then 20.6g of (NH4)6W7O was added. 24 ·6H2O and 2.4 g of Ni(NO3)2·6H2O were added to the above solution, stirred for 10 min, and then sonicated for 4 h. The solution was then placed in an oven and dried at 90 °C. The dried solid was then heated from 20 °C to 700 °C at a rate of 5 °C / min in a nitrogen stream of 100 ml / min for 1 h; finally, it was heated from 700 °C to 900 °C at a rate of 2 °C / min in a stream of H2 of 80 ml / min and CH4 of 20 ml / min for 2 h to obtain Ni. 0.1 W 0.2 C catalyst.

[0030] Example 3

[0031] 1g of activated charcoal was soaked in 20ml of deionized water. Then 10.3g of (NH4)6W7O was added. 24·6H2O and 4.8 g of Ni(NO3)2·6H2O were added to the above solution, stirred for 10 min, and then sonicated for 4 h. The solution was then placed in an oven and dried at 90 °C. The dried solid was then heated from 20 °C to 700 °C at a rate of 5 °C / min in a nitrogen stream of 100 ml / min for 1 h; finally, it was heated from 700 °C to 900 °C at a rate of 2 °C / min in a stream of H2 of 80 ml / min and CH4 of 20 ml / min for 2 h to obtain Ni. 0.2 W 0.1 C catalyst.

[0032] Example 4

[0033] Soak 1g of activated charcoal in 50ml of deionized water. Then, add 31g of (NH4)6W7O. 24 ·6H2O and 2.4 g of Ni(NO3)2·6H2O were added to the above solution, stirred for 10 min, and then sonicated for 4 h. The solution was then placed in an oven and dried at 90 °C. The dried solid was then heated from 20 °C to 700 °C at a rate of 5 °C / min in a nitrogen stream of 100 ml / min for 1 h; finally, it was heated from 700 °C to 900 °C at a rate of 2 °C / min in a stream of H2 of 80 ml / min and CH4 of 20 ml / min for 2 h to obtain Ni. 0.1 W 0.3 C catalyst.

[0034] Example 5

[0035] 1g of activated charcoal was soaked in 50ml of deionized water. Then 10.3g of (NH4)6W7O was added. 24 ·6H2O and 7.2 g of Ni(NO3)2·6H2O were added to the above solution, stirred for 10 min, and then sonicated for 4 h. The solution was then placed in an oven and dried at 90 °C. The dried solid was then heated from 20 °C to 700 °C at a rate of 5 °C / min in a nitrogen stream of 100 ml / min for 1 h; finally, it was heated from 700 °C to 900 °C at a rate of 2 °C / min in a stream of H2 of 80 ml / min and CH4 of 20 ml / min for 2 h to obtain Ni. 0.3 W 0.1 C catalyst.

[0036] Example 6

[0037] Based on Example 2, the heating rate of the solid in a 100 ml / min nitrogen flow was investigated. NiWC catalysts were prepared using different heating rates, and their catalytic activity was compared. Catalysts prepared at different heating rates of 1℃ / min, 2℃ / min, 5℃ / min, 10℃ / min, and 20℃ / min were labeled as Ni 0.1 W 0.2 C-1-1, Ni 0.1 W 0.2 C-1-2, Ni 0.1 W 0.2 C-1-5, Ni 0.1 W 0.2 C-1-10, Ni 0.1 W 0.2 C-1-20.

[0038] Example 7

[0039] Based on Example 2, the heating rates of the solid in 80 ml / min H2 and 20 ml / min CH4 streams were investigated. Catalysts prepared at different heating rates of 1 °C / min, 2 °C / min, 5 °C / min, 10 °C / min, and 20 °C / min were labeled as Ni. 0.1 W 0.2 C-2-1, Ni 0.1 W 0.2 C-2-2, Ni 0.1 W 0.2 C-2-5, Ni 0.1 W 0.2 C-2-10, Ni 0.1 W 0.2 C-2-20.

[0040] Experimental example:

[0041] 1. The NiWC catalysts obtained in Examples 1-5 were added to the catalytic reaction. The reaction process was as follows: 0.5g of catalyst was loaded into a straight-tube quartz reactor with a diameter of 1cm, and the reactor was heated to the target temperature for reaction. The gas flow rate at the reactor inlet was 200mL / min, and the gas composition was 3% H2 and 97% air. The composition of the gas after the reaction was analyzed using a mass spectrometer at the reactor outlet.

[0042] like Figure 2 The figure shows the hydrogen conversion rate versus reaction temperature curves for NiWC catalysts prepared with different Ni:W ratios. By comparison, the catalyst activity increases with increasing W content and decreasing Ni content. The Ni:W ratios of 1:2 and 1:3 result in higher Ni... 0.1 W 0.2 C catalyst (Example 2, its TEM image is shown below) Figure 1 (as shown), Ni 0.1 W 0.3 The C catalyst achieves 100% conversion at 100℃. Below 100℃, a Ni:W ratio of 1:3 exhibits higher catalytic activity. However, as the W content continues to increase, the catalyst activity initially plateaus and then decreases. Therefore, a Ni:W ratio of 1:2 to 1:3 is preferable.

[0043] 2. The Ni obtained in Example 2 0.1 W 0.2 A comparison of the reaction of C catalyst with Pt, Pd, Ni, Cu, Fe, and WC is shown. Figure 3 The figure shows the hydrogen conversion rate versus reaction temperature curves for NiWC catalysts prepared with different active components. It can be seen from the figure that Pt exhibits the highest catalytic activity, while WC shows the lowest, but the overall catalytic activities of Pt, Pd, and NiWC are relatively similar. At 80℃, the low-temperature catalytic combustion conversion of H2 can reach 100% under Pt and Pd catalysis. At 100℃, the low-temperature catalytic combustion conversion of H2 can reach 100% under NiWC catalysis. Non-noble metal catalysts such as Ni, Cu, and Fe show lower catalytic activity.

[0044] 3. The catalyst obtained in Example 6 is added to the catalytic reaction, such as... Figure 4 As shown, Figure 4 The bar chart shows the effect of different heating rates in the first heating stage on the hydrogen conversion rate at 100℃. The heating rate in the first stage likely determines the morphology of the Ni nanoparticles; excessively rapid heating rates can lead to the formation of large clusters of Ni nanoparticles, resulting in reduced catalytic activity. As can be seen from the figure, the activity of the prepared catalyst gradually decreases when the heating rate exceeds 5℃ / min.

[0045] 4. The catalyst obtained in Example 7 is added to the catalytic reaction, such as... Figure 5 The figure shows a bar chart illustrating the effect of different heating rates in the second heating stage on the hydrogen conversion rate at 100℃. The heating rate in the second stage may determine the morphology of the WC formation. NiWC catalysts were prepared using different heating rates, and their catalytic activities were compared. The figure shows that the catalyst prepared at a heating rate of 2℃ / min exhibits the highest activity.

[0046] The above embodiments are merely one of the preferred embodiments of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but solve the same technical problem as the present invention, should be included within the scope of protection of the present invention.

Claims

1. The application of NiWC catalyst as a catalyst in low-temperature H2 reactions, wherein the low-temperature reaction is a hydrogen catalytic combustion reaction at 80-100℃, characterized in that, The preparation steps of the NiWC catalyst include the following steps: (1) Soak activated carbon in 20 ml of deionized water; (2) (NH4)6W7O with a Ni:W molar ratio of 1:2 to 1:3 24 ·6H2O and Ni(NO3)2·6H2O were added to deionized water soaked with activated carbon, stirred and sonicated; (3) Place the solution obtained in step (2) into an oven and dry it at 90°C; (4) The dried solid is heated from 20°C to 700°C in nitrogen at a heating rate of 1~5°C / min for 1 h; then heated from 700°C to 900°C in H2 / CH4 at a heating rate of 1~2°C / min for 2 h to obtain NiWC catalyst, wherein the volume ratio of H2 / CH4 is 4:1 and the flow rate is 100 ml / min.

2. The application as described in claim 1, characterized in that, In step (4), the solid is heated from 20°C to 700°C at a heating rate of 5°C / min in nitrogen.

3. The application as described in claim 1, characterized in that, The nitrogen gas is a nitrogen flow rate of 100 ml / min.

4. The application as described in claim 1, characterized in that, When the solid is in H2 / CH4, the temperature is increased from 700℃ to 900℃ at a heating rate of 2℃ / min.

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