Preparation method and application of ammonia decomposition hydrogen production catalyst Co-Nd / ATP

Abstract

The present application relates to ammonia decomposition hydrogen production technical field, specifically relates to a kind of preparation and application of ammonia decomposition hydrogen production catalyst Co-Nd / ATP.The conventional transition metal-based catalyst is difficult to achieve about 90% ammonia decomposition conversion rate at temperature below 700 DEG C.For the above problems, the present application provides a kind of ammonia decomposition hydrogen production catalyst Co-Nd / ATP, the catalyst is introduced Co and Nd two kinds of catalytic activity element on the surface of attapulgite material, the catalyst has good catalytic activity to ammonia decomposition hydrogen production reaction, using the catalyst, the ammonia decomposition conversion rate can reach more than 90% at about 600 DEG C temperature catalytic reaction, relative to conventional ammonia decomposition hydrogen production transition metal-based catalyst has better catalytic effect.

Description

Technical Field

[0001] This invention relates to the field of ammonia decomposition for hydrogen production technology, specifically to a method for preparing and applying a Co-Nd / ATP catalyst for ammonia decomposition for hydrogen production. Background Technology

[0002] The world faces energy depletion and environmental pollution caused by fossil fuel use, urgently requiring the development of efficient, green, and clean energy sources. Hydrogen energy, due to its cleanliness and efficiency, has become a key research focus. Global demand for hydrogen energy is growing rapidly. However, significant challenges remain in hydrogen storage and utilization. Ammonia, as a hydrogen carrier, offers advantages such as high yield, high hydrogen content (17.8 wt%), low storage pressure, and long-term storage stability.

[0003] Ammonia decomposition is one of the important pathways for hydrogen production. Catalytically decomposing ammonia can yield large quantities of hydrogen, which is crucial for the development of a hydrogen economy. The catalysts used in ammonia decomposition for hydrogen production are typically ruthenium-based or transition metal-based catalysts. Ruthenium-based catalysts are expensive, and conventional transition metal-based catalysts struggle to achieve a 90% ammonia conversion rate at temperatures below 700°C. Summary of the Invention

[0004] A problem with existing technologies is that conventional transition metal-based catalysts struggle to achieve ammonia decomposition conversion rates above 88% at temperatures below 700°C. To address this issue, this invention provides a Co-Nd / ATP catalyst for ammonia decomposition to hydrogen production, comprising the following preparation steps:

[0005] (1) Attapulgite powder (ATP carrier powder) was impregnated in an aqueous solution of soluble neodymium salt. After impregnation, it was dried to obtain Nd / ATP precursor.

[0006] (2) The Nd / ATP precursor was calcined in air atmosphere. After calcination, Nd / ATP was obtained.

[0007] (3) Nd / ATP was uniformly dispersed in an aqueous solution formed by mixing soluble cobalt salt and citric acid and heated and stirred. After the reaction was completed, it was dried to obtain the Co-Nd / ATP precursor.

[0008] (4) The Co-Nd / ATP precursor was calcined in air. After calcination, Co-Nd / ATP was obtained.

[0009] Preferably, in step (1), the mass ratio of ATP carrier powder to neodymium in the aqueous solution is 1:0.025-0.07.

[0010] Preferably, the soluble neodymium salt is neodymium nitrate hexahydrate, and the mass ratio of ATP carrier powder to neodymium nitrate hexahydrate is 0.5:0.076.

[0011] Preferably, the soaking time in step (1) is not less than 24 hours.

[0012] Preferably, the drying temperature in step (1) is not greater than 100°C.

[0013] Preferably, the roasting temperature in step (2) is not higher than 500°C and the roasting time is not more than 3 hours.

[0014] Preferably, the soluble cobalt salt in step (3) is cobalt nitrate, and the mass ratio of Co-Nd / ATP precursor to cobalt and citric acid is 0.3:0.59:0.38-0.40.

[0015] Preferably, the roasting temperature in step (4) is not higher than 700°C and the roasting time is not more than 4 hours.

[0016] The present invention has the following beneficial effects:

[0017] (1) The Co-Nd / ATP obtained in this invention has good catalytic activity for ammonia decomposition to hydrogen production. When the reaction is carried out using this catalyst at a temperature of about 600°C, the ammonia decomposition conversion rate can reach more than 90%, which is better than conventional transition metal-based catalysts for ammonia decomposition to hydrogen production.

[0018] (2) Through research, this invention found that the amount of Nd added during the Co-Nd / ATP preparation process has a significant impact on the catalytic activity of the obtained catalyst. When the mass ratio of ATP carrier powder to neodymium nitrate hexahydrate is 0.5:0.076 during the reaction process, the catalyst obtained has better catalytic activity compared to other mass ratios. Attached Figure Description

[0019] Figure 1 Comparison chart of ammonia decomposition conversion rate test results in the process of catalytic ammonia decomposition to hydrogen production by the catalysts obtained in Examples 1-3 and Comparative Example 1.

[0020] Figure 2 Comparison of hydrogen generation rate test results during the catalytic ammonia decomposition hydrogen production process of the catalysts obtained in Examples 1-3 and Comparative Example 1.

[0021] Figure 3 Comparison of activation energy test results in the process of hydrogen production by catalytic ammonia decomposition using catalysts obtained in Examples 1-3 and Comparative Example 1.

[0022] Figure 4XRD comparison of ATP carrier powder with 40Co5Nd / ATP and 40Co / ATP.

[0023] Figure 5 TEM image of 40Co / ATP.

[0024] Figure 6 TEM image of 40Co5Nd / ATP. Detailed Implementation

[0025] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0026] The catalytic activity of the catalysts obtained in the following embodiments and comparative examples of the present invention for ammonia decomposition to hydrogen production was tested according to the following steps:

[0027] A quartz tube with an inner diameter of 4 mm and a length of 0.5 m was used as the reactor. 0.1 g of catalyst was placed in the quartz tube, and the reactor temperature was raised to different specified temperatures and held for 30 min. NH3 was then continuously and uniformly introduced from one end of the quartz tube and discharged from the other end at a flow rate of 50 mL / min. The discharged gases at different temperatures were collected within the same sampling time, and the volume content of NH3 in the product was analyzed using a thermal conductivity detector of a gas chromatograph set to 150 °C. H2 was used as the carrier gas in the chromatograph at a flow rate of 40 mL / min. The chromatographic column was a dedicated amine analysis column from Shanghai Oni, with a column temperature set to 110 °C.

[0028] The ammonia decomposition conversion rate is calculated according to the following formula:

[0029]

[0030] in,

[0031] in, For NH3 conversion rate, This represents the total amount of ammonia in the raw gas. This represents the volume content of unreacted NH3.

[0032] The ATP carrier powder used in the following examples and comparative examples of this invention was purchased from Yuanye Biotechnology Co., Ltd., catalog number S28335.

[0033] Example 1

[0034] The preparation method of the Co-Nd / ATP catalyst for hydrogen production from ammonia decomposition is as follows:

[0035] (1) Weigh 0.5g of ATP carrier powder and 0.045g of Nd(NO3)3·6H2O and add them to 20mL of deionized water. Stir and disperse evenly, let stand and age for 24h, and then dry the mixture at 100℃ for 8h to obtain Nd / ATP precursor.

[0036] (2) The Nd / ATP precursor was placed in a muffle furnace and calcined at 500℃ for 3 hours. After naturally cooling to room temperature, Nd / ATP was obtained. The heating rate during the calcination process was 5℃ / min.

[0037] (3) Weigh 0.3g Nd / ATP and 0.59g Co(NO3)2·6H2O and add them to 50mL of deionized water. Disperse and stir evenly. During the stirring process, add 0.427g citric acid monohydrate. Heat and stir at 85℃ for 8h. After the reaction is completed, dry the obtained reaction solution at 100℃ for 12h to obtain Co-Nd / ATP precursor.

[0038] (4) Then the Co-Nd / ATP precursor was placed in a muffle furnace and calcined at 700℃ for 4h. After naturally cooling to room temperature, the target catalyst was obtained, which was denoted as 40Co3Nd / ATP. The heating rate during the calcination process was 5℃ / min.

[0039] Example 2 is the same as Example 1, except that the amount of Nd(NO3)3·6H2O added in step (1) of Example 2 is 0.076g. The catalyst obtained in Example 2 is denoted as 40Co5Nd / ATP.

[0040] Example 3 is the same as Example 1, except that the amount of Nd(NO3)3·6H2O added in step (1) of Example 3 is 0.076g. The catalyst obtained in Example 3 is denoted as 40Co7Nd / ATP.

[0041] Comparative Example 1

[0042] (1) Weigh 0.3g ATP and 0.59g Co(NO3)2·6H2O and add them to 50mL of deionized water and stir evenly. During the stirring process, add 0.427g citric acid monohydrate and heat and stir at 85℃ for 8h. After the reaction is completed, dry the obtained reaction solution at 100℃ for 12h to obtain the Co / ATP precursor.

[0043] (2) Finally, the Co / ATP precursor was placed in a muffle furnace and calcined at 700℃ for 4 hours. After naturally cooling to room temperature, the target catalyst was obtained, which was denoted as 40Co / ATP. The heating rate during the calcination process was 5℃ / min.

[0044] The ammonia decomposition conversion rate, hydrogen generation rate, and activation energy of the catalysts obtained in Examples 1-3 and Comparative Example 1 during the catalytic ammonia decomposition to hydrogen production process are as shown in the appendix to the specification. Figure 1-3 As shown in the test results, 40Co5Nd / ATP exhibits the best performance across all parameters. When 40Co5Nd / ATP catalyzes ammonia decomposition, the NH3 conversion rate reaches 94.6% at 600℃, and the hydrogen production rate is 31.66 mmol gcat. -1 min -1 The activation energy of the reaction is 67.97 kJ / mol. -1 .

[0045] When 40Co3Nd / ATP catalyzes the decomposition of ammonia, the NH3 conversion rate reaches 88.7% at 600℃, and the hydrogen production rate is 29.7 mmol gcat. -1 min -1 The activation energy of the reaction is 52.5 kJ / mol. -1 .

[0046] When 40Co7Nd / ATP catalyzes the decomposition of ammonia, the NH3 conversion rate reaches 91.7% at 600℃, and the hydrogen production rate is 30.71 mmol gcat. -1 min -1 The activation energy of the reaction is 75.71 kJ / mol. -1 .

[0047] When 40Co / ATP catalyzes the decomposition of ammonia, the NH3 conversion rate reaches 85.4% at 600℃, and the hydrogen production rate is 28.61 mmol gcat. -1 min -1 The activation energy of the reaction is 83.63 kJ / mol. -1 .

[0048] The XRD diffraction patterns of the ATP carrier powder, 40Co5Nd / ATP, and 40Co / ATP are shown in the attached instruction manual. Figure 4 As shown in the image, the ATP support exhibits distinct diffraction peaks at 2θ = 22.3° and 28.6°. Both 40Co5Nd / ATP and 40Co / ATP catalysts show characteristic Co3O4 diffraction peaks at 2θ = 31.2°, 36.8°, and 65.2°, corresponding to their (220), (311), and (440) crystal planes, respectively (PDF#09-0418). The characteristic diffraction peaks of Nd2O3 for the 40Co5Nd / ATP catalyst were not clearly observed in the XRD pattern, which may be due to the low loading content and small particle size of Nd2O3.

[0049] TEM images of 40Co / ATP are attached to the instruction manual. Figure 5As shown in the image, the Co3O4 catalyst particles are uniformly distributed on the support. The corresponding HRTEM image clearly shows that the Co3O4 lattice fringe spacing is 0.244 nm, belonging to the (311) crystal plane of the Co3O4 crystal, which is consistent with the XRD results.

[0050] TEM images of 40Co5Nd / ATP are attached to the instruction manual. Figure 6 As shown in the image, the catalyst Co3O4 and Nd2O3 particles are uniformly distributed on the support. The corresponding HRTEM image clearly shows that the Co3O4 lattice fringe spacing is 0.244 nm, belonging to the (311) crystal plane of Co3O4. The Nd2O3 lattice fringe spacing is 0.335 nm, belonging to the (100) crystal plane of Co3O4, which is consistent with the XRD results.

[0051] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A Co-Nd / ATP catalyst for hydrogen production from ammonia decomposition, characterized in that, The preparation method includes the following steps: (1) The ATP carrier powder was impregnated in an aqueous solution of soluble neodymium salt. After impregnation, it was dried to obtain the Nd / ATP precursor. (2) The Nd / ATP precursor was calcined in air atmosphere. After calcination, Nd / ATP was obtained. (3) Nd / ATP was uniformly dispersed in an aqueous solution formed by mixing soluble cobalt salt and citric acid and heated and stirred. After the reaction was completed, it was dried to obtain the Co-Nd / ATP precursor. (4) The Co-Nd / ATP precursor was calcined in air. After calcination, Co-Nd / ATP was obtained.

2. The Co-Nd / ATP catalyst for ammonia decomposition to hydrogen production according to claim 1, characterized in that, In step (1), the mass ratio of ATP carrier powder to neodymium in the aqueous solution is 1:0.025-0.

07.

3. The Co-Nd / ATP catalyst for ammonia decomposition to hydrogen production according to claim 2, characterized in that, The soluble neodymium salt is neodymium nitrate hexahydrate, and the mass ratio of ATP carrier powder to neodymium nitrate hexahydrate is 0.5:0.

076.

4. The Co-Nd / ATP catalyst for ammonia decomposition to hydrogen production according to claim 1, characterized in that, The soaking time in step (1) shall not be less than 24 hours.

5. The Co-Nd / ATP catalyst for ammonia decomposition to hydrogen production according to claim 1, characterized in that, The drying temperature in step (1) shall not exceed 100℃.

6. The Co-Nd / ATP catalyst for ammonia decomposition to hydrogen production according to claim 1, characterized in that, The roasting temperature in step (2) shall not exceed 500℃ and the roasting time shall not exceed 3h.

7. The Co-Nd / ATP catalyst for hydrogen production from ammonia decomposition according to claim 1, characterized in that, In step (3), the soluble cobalt salt is cobalt nitrate, and the mass ratio of the Co-Nd / ATP precursor to cobalt and citric acid is 0.3:0.59:0.38-0.

40.

8. The Co-Nd / ATP catalyst for ammonia decomposition to hydrogen production according to claim 1, characterized in that, The roasting temperature in step (4) shall not exceed 700℃ and the roasting time shall not exceed 4h.

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