Preparation method and application of Ni / Ba-Nd2O3 catalyst

Abstract

The present application relates to ammonia decomposition hydrogen production technical field, specifically to a kind of preparation method and application of Ni / Ba-Nd2O3 catalyst.The conventional transition metal-based catalyst is difficult to achieve 90% ammonia decomposition conversion rate at less than 700 DEG C temperature.Aiming at the above problems, the present application provides a kind of preparation method of Ni / Ba-Nd2O3 catalyst, which uses Ba element to first carry out chemical doping modification to Nd2O3 to obtain Ba-Nd2O3, also uses Ni element to carry out chemical doping modification to Ba-Nd2O3, finally obtains Ni / Ba-Nd2O3, and the obtained Ni / Ba-Nd2O3 has good catalytic activity to ammonia decomposition hydrogen production reaction, at the temperature of not more than 700 DEG C (about 600 DEG C), the catalyst can achieve more than 90% ammonia decomposition conversion rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogen production by ammonia decomposition, and particularly relates to a preparation method and application of a Ni / Ba-Nd2O3 catalyst. BACKGROUND

[0002] The global energy is facing exhaustion and environmental pollution caused by the use of fossil fuels, and it is urgent to develop efficient green clean energy. Hydrogen energy has become the focus of research due to its clean and efficient characteristics. The demand for hydrogen energy is rapidly growing worldwide. However, there are still major difficulties in the storage and utilization of hydrogen. Ammonia, as a hydrogen carrier, has the advantages of high yield, high hydrogen content (17.8wt%), low storage pressure, and long-term storage stability. Catalytic ammonia decomposition can directly provide high-purity hydrogen for proton exchange membrane fuel cells, avoiding the poisoning of Pt electrodes in the battery.

[0003] The ammonia decomposition reaction is a reversible reaction, and the main reaction steps are the adsorption of NH3 molecules on the catalyst, the continuous desorption of H on the surface of NH3, the formation of N and H atoms, and finally the adsorption of N and H through recombination to form N2 and H2. Currently, the active metals mainly used in the research of ammonia decomposition for hydrogen production are Ru, Ni, Co, Fe, Mo and other active metals. The price of Ru-based catalysts is expensive, and the cost is high. It is difficult for conventional transition metal-based catalysts to achieve 90% ammonia decomposition conversion rate at a temperature lower than 700 DEG C. SUMMARY

[0004] The existing problem is that it is difficult for conventional transition metal-based catalysts to achieve 90% ammonia decomposition conversion rate at a temperature lower than 700 DEG C. In view of the above problems, the present application provides a preparation method of a Ni / Ba-Nd2O3 catalyst, which comprises the following preparation steps:

[0005] (1) The soluble neodymium salt is placed in deionized water, and ammonia water is used to adjust the solution to be alkaline. After the stirring reaction is completed, the product is vacuum dried, and the dried product is calcined in an air atmosphere to obtain a Nd2O3 carrier;

[0006] (2) Ba(NO3)2 is dissolved in deionized water to obtain a barium nitrate solution, and the Nd2O3 carrier obtained in step (1) is placed in the barium nitrate solution, and after immersion and aging, drying treatment is performed, and the dried product is calcined in an air atmosphere to obtain Ba-Nd2O3;

[0007] (3) The soluble nickel salt is dissolved in deionized water, and then the Ba-Nd2O3 carrier is added, and after stirring, immersion and aging, drying treatment is performed to obtain a precursor;

[0008] (4) The precursor is calcined in an air atmosphere to obtain Ni / Ba-Nd2O3.

[0009] Preferably, the mass ratio of Ba(NO3)2 to Nd2O3 carrier in step (2) is 0.053-0.095:0.5.

[0010] Preferably, the mass ratio of Ba(NO3)2 to Nd2O3 carrier in step (2) is 0.074:0.5.

[0011] Preferably, the calcination temperature in step (1) is not less than 650℃, the calcination time is not less than 4h, and the temperature rising rate is not more than 5℃·min -1 .

[0012] Preferably, the calcination temperature in step (2) is not less than 700℃, the calcination time is not less than 4h, and the temperature rising rate is not more than 5℃·min -1 .

[0013] Preferably, the impregnation aging time in step (2) is not less than 24h.

[0014] Preferably, the impregnation aging time in step (3) is not less than 24h.

[0015] Preferably, the calcination temperature in step (4) is not less than 700℃, the calcination time is not less than 4h, and the temperature rising rate is not more than 5℃·min -1 .

[0016] Preferably, the mass ratio of the soluble nickel salt to Ba-Nd2O3 carrier is 0.52:0.3.

[0017] Preferably, the soluble nickel salt is Ni(NO3)2·6H2O.

[0018] The present application has the following beneficial effects:

[0019] (1) The Ni / Ba-Nd2O3 obtained by the present application has good catalytic effect on the hydrogen production reaction by ammonia decomposition, and no noble metal active substance such as Ru is used in the preparation process, so the cost is lower and the market competitiveness is better.

[0020] (2) The present application found that, in the preparation process of Ni / Ba-Nd2O3, the mass ratio of Ba(NO3)2 to Nd2O3 carrier is 0.074:0.5, which has better catalytic activity than other mass ratios of Ba(NO3)2 to Nd2O3 carrier, and the obtained 35Ni / 7Ba-Nd2O3 has better catalytic activity for the hydrogen production reaction by ammonia decomposition, and at a temperature of about 600℃, the catalyst can realize an ammonia decomposition conversion rate of more than 90%. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1NH3 conversion rate of the ammonia decomposition hydrogen production catalysts obtained in Examples 1-3 and Comparative Example 1 when catalyzing ammonia decomposition at different temperatures.

[0022] Figure 2 Hydrogen production rate of the ammonia decomposition hydrogen production catalysts obtained in Examples 1-3 and Comparative Example 1 when catalyzing ammonia decomposition at different temperatures.

[0023] Figure 3 Reaction activation energy required by the ammonia decomposition hydrogen production catalysts obtained in Examples 1-3 and Comparative Example 1 when catalyzing ammonia decomposition.

[0024] Figure 4 XRD diffractogram of the ammonia decomposition hydrogen production catalysts obtained in Example 2 and Comparative Example 1.

[0025] Figure 5 TEM image of the ammonia decomposition hydrogen production catalyst obtained in Example 2. DETAILED DESCRIPTION

[0026] The present application will be described in detail below with reference to the following examples. It should be understood, however, that the following examples are merely illustrative of the present application and should not be construed as limiting the scope of the present application.

[0027] The ammonia decomposition hydrogen production catalytic activity of the catalysts obtained in the following examples of the present application was tested according to the following steps:

[0028] A quartz tube was used as the reactor, the inner diameter of the quartz tube was 4 mm and the length was 0.5 m. 0.1 g of catalyst was placed in the quartz tube, and then the temperature of the reactor was raised to different specified temperatures, and kept constant for 30 min. NH3 was then continuously and uniformly introduced into the quartz tube at a flow rate of 50 mL / min, and the gas discharged from the other end of the quartz tube was collected at the same sampling time. The volume content of NH3 in the product was analyzed using a thermal conductivity detector of a North Division gas chromatograph, the detector temperature was set to 150°C, H2 was used as the carrier gas of the chromatograph, the carrier gas flow rate was 40 mL / min, and a special column for amine analysis from Shanghai Onyi was used, and the column temperature was set to 110°C.

[0029] The ammonia decomposition conversion rate was calculated according to the following formula:

[0030]

[0031] wherein,

[0032] wherein, is the NH3 conversion rate, is the total amount of ammonia in the raw gas, is the volume content of unreacted NH3.

[0033] Example 1

[0034] A preparation method of the Ni / Ba-Nd2O3 catalyst is as follows:

[0035] (1) 2 g of Nd(NO3)3·6H2O was placed in 100 mL of deionized water, and ammonia water was slowly added to adjust the solution pH to 10. After stirring for 1 h, the reaction solution was dried at 80°C, and the dried product was calcined in a muffle furnace under an air atmosphere to obtain a Nd2O3 carrier. The calcination temperature was 650°C, the calcination time was 4 h, and the temperature rise rate was 5°C·min -1 ;

[0036] (2) 0.053 g of Ba(NO3)2 was dissolved in 20 mL of deionized water, and 0.5 g of the Nd2O3 carrier was placed in the barium nitrate solution. After being immersed and aged for 24 h, drying treatment was performed, and the dried product was calcined in a muffle furnace under an air atmosphere to obtain 5Ba-Nd2O3. The calcination temperature was 700°C, the calcination time was 4 h, and the temperature rise rate was 5°C·min -1 ;

[0037] (3) 0.52 g of Ni(NO3)2·6H2O was dissolved in 20 mL of deionized water to obtain a nickel nitrate solution. 0.3 g of the Ba-Nd2O3 carrier was placed in the nickel nitrate solution, and after being immersed and aged for 24 h, drying treatment was performed to obtain a precursor. The precursor was then calcined in a muffle furnace under an air atmosphere. The calcination temperature was 700°C, the calcination time was 4 h, and the temperature rise rate was 5°C·min -1 . The catalyst obtained in Example 1 was recorded as 35Ni / 5Ba-Nd2O3.

[0038] Example 2 was the same as Example 1, except that the addition amount of Ba(NO3)2 in step (2) of Example 2 was 0.074 g.

[0039] The catalyst obtained in Example 2 was recorded as 35Ni / 7Ba-Nd2O3.

[0040] Example 3 was the same as Example 1, except that the addition amount of Ba(NO3)2 in step (2) of Example 3 was 0.095 g.

[0041] The catalyst obtained in Example 3 was recorded as 35Ni / 9Ba-Nd2O3.

[0042] Comparative Example 1

[0043] A preparation method of 35Ni / Nd2O3 is as follows:

[0044] 2g of Nd(NO3)3·6H2O was placed in 100 mL of deionized water, and ammonia water was slowly added to adjust the solution pH to 10. After stirring the reaction for 1 h, the reaction solution was dried at 80°C. The dried product was calcined in a muffle furnace under an air atmosphere, the calcination temperature was 650°C, the calcination time was 4 h, and the heating rate was 5°C·min -1 ;

[0045] 0.52 g of Ni(NO3)2·6H2O was dissolved in 20 mL of deionized water to obtain a nickel nitrate solution. 0.3 g of Nd2O3 carrier was placed in the nickel nitrate solution, and after aging for 24 h, drying treatment was performed to obtain a precursor. The precursor was then calcined in a muffle furnace under an air atmosphere, the calcination temperature was 700°C, the calcination time was 4 h, and the heating rate was 5°C·min -1 , to obtain the catalyst 35Ni / Nd2O3.

[0046] The ammonia decomposition conversion rate, hydrogen generation rate, and reaction activation energy of the catalysts obtained in Examples 1-3 and Comparative Example 1 in the process of ammonia decomposition for hydrogen production are shown in the test results shown in the accompanying drawings of the specification Figures 1-3 . The test results show that the performance of 35Ni / 7Ba-Nd2O3 is the best. When 35Ni / 7Ba-Nd2O3 catalyzes ammonia decomposition, the NH3 conversion rate is 96.8% at 600°C, the hydrogen generation rate is 32.41 mmol gcat -1 min -1 , and the reaction activation energy is 53.6 kJ mol -1 .

[0047] When 35Ni / 5Ba-Nd2O3 catalyzes ammonia decomposition, the NH3 conversion rate is 92.7% at 600°C, the hydrogen generation rate is 31.03 mmol gcat -1 min -1 , and the reaction activation energy is 60.7 kJ mol -1 .

[0048] When 35Ni / 9Ba-Nd2O3 catalyzes ammonia decomposition, the NH3 conversion rate is 91.6% at 600°C, the hydrogen generation rate is 30.68 mmol gcat -1 min -1 , and the reaction activation energy is 65.3 kJ mol -1 .

[0049] The XRD diffraction patterns of 35Ni / 7Ba-Nd2O3 and 35Ni / Nd2O3 are shown in the accompanying drawings of the specification Figure 4As shown in the image, after loading Ni onto Ba-Nd2O3, the characteristic diffraction peaks at 2θ = 37.2°, 43.3°, and 62.8° correspond to the (111), (200), and (220) crystal planes of NiO, respectively, indicating that Ni was successfully loaded onto Nd2O3 in the form of NiO nanoparticles. In addition to the characteristic diffraction peaks of Nd2O3 and NiO, the Ba-doped catalyst 35Ni / 7Ba-Nd2O3 clearly shows diffraction peaks of BaO, indicating that Ba was successfully doped into the molecular structure of the catalyst.

[0050] TEM images of 35Ni / 7Ba-Nd2O3 are attached to the instruction manual. Figure 5 As shown in the image, the catalyst NiO particles are uniformly distributed on the Nd2O3 support. The corresponding HRTEM image clearly shows that the NiO lattice fringe spacing is 0.218 nm, belonging to the (200) crystal plane of NiO, 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 method for preparing a Ni / Ba-Nd2O3 catalyst, characterized in that, The preparation steps include the following: (1) Soluble neodymium salt was placed in deionized water, and the solution was adjusted to alkaline with ammonia. After the reaction was completed by stirring, the product was vacuum dried and the dried product was calcined in air to obtain Nd2O3 support. (2) Dissolve Ba(NO3)2 in deionized water to obtain barium nitrate solution. Place the Nd2O3 support obtained in step (1) in the barium nitrate solution, impregnate and age it, and then dry it. Calcine the dried product in air atmosphere to obtain Ba-Nd2O3. (3) Dissolve the soluble nickel salt in deionized water, then add Ba-Nd2O3 support, stir, impregnate and age, and then dry to obtain the precursor; (4) The precursor was calcined in air to obtain Ni / Ba-Nd2O3; In step (2), the mass ratio of Ba(NO3)2 to Nd2O3 support is 0.053-0.095:0.5; The mass ratio of the soluble nickel salt to the Ba-Nd2O3 support is 0.52:0.

3.

2. The method for preparing a Ni / Ba-Nd2O3 catalyst according to claim 1, characterized in that, In step (2), the mass ratio of Ba(NO3)2 to Nd2O3 support is 0.074:0.

5.

3. The method for preparing a Ni / Ba-Nd2O3 catalyst according to claim 1, characterized in that, In step (1), the calcination temperature shall not be lower than 650℃, the calcination time shall not be less than 4 hours, and the heating rate shall not be greater than 5℃·min. -1 .

4. The method for preparing a Ni / Ba-Nd2O3 catalyst according to claim 1, characterized in that, In step (2), the calcination temperature shall not be lower than 700℃, the calcination time shall not be less than 4 hours, and the heating rate shall not be greater than 5℃·min. -1 .

5. The method for preparing a Ni / Ba-Nd2O3 catalyst according to claim 1, characterized in that, The soaking and aging time in step (2) shall not be less than 24 hours.

6. The method for preparing a Ni / Ba-Nd2O3 catalyst according to claim 1, characterized in that, The soaking and aging time in step (3) shall not be less than 24 hours.

7. The method for preparing a Ni / Ba-Nd2O3 catalyst according to claim 1, characterized in that, In step (4), the calcination temperature shall not be lower than 700℃, the calcination time shall not be lower than 4h, and the heating rate shall not be greater than 5℃·min. -1 .

8. The method for preparing a Ni / Ba-Nd2O3 catalyst according to claim 1, characterized in that, The soluble nickel salt is Ni(NO3)2·6H2O.

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