WO 3 NiO / ZnO oxygen carriers, their preparation methods and applications
By preparing a WO3-NiO/ZnO composite oxygen carrier, the problems of low activity and poor stability of existing catalysts in the process of hydrogen production from ammonia decomposition were solved, and efficient and stable hydrogen production was achieved, which is suitable for ammonia oxidative dehydrogenation reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WEIFANG UNIVERSITY
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-01
AI Technical Summary
Existing catalysts have low activity and high cost in the process of hydrogen production from ammonia decomposition, and are prone to chemical poisoning in sulfur-containing and water-containing environments, making it difficult to achieve efficient and stable hydrogen production.
The WO3-NiO/ZnO composite oxygen carrier was prepared by co-precipitation and stepwise calcination processes. The synergistic effect between the components was controlled by combining inert atmosphere and air calcination to improve catalytic activity and selectivity.
It achieves efficient hydrogen production from ammonia decomposition at relatively low temperatures, with high purity of the produced hydrogen, good catalyst stability, and excellent recyclability, making it suitable for industrial applications.
Smart Images
Figure CN121669256B_ABST
Abstract
Description
WO3-NiO / ZnO oxygen carrier, its preparation method and application Technical Field
[0001] This invention belongs to the field of ammonia-to-hydrogen technology, specifically relating to a WO3-NiO / ZnO oxygen carrier, its preparation method, and its application. Background Technology
[0002] As the global energy structure shifts towards a low-carbon model, the demand for hydrogen energy, as a clean, efficient, and renewable energy carrier, continues to grow. However, hydrogen is flammable and explosive at room temperature and pressure, and has a low volumetric energy density, resulting in high storage and transportation costs and low safety, which has become a major bottleneck for the industrialization of hydrogen energy.
[0003] Ammonia (NH3) molecules contain only nitrogen and hydrogen, with a hydrogen mass percentage as high as 17.6%. Its energy density is 3000 Wh / kg, significantly higher than methanol and other fuels. Ammonia is a gas at room temperature and pressure, easily liquefied, and its storage and transportation costs are only 1 / 2 to 1 / 3 that of hydrogen. Furthermore, it has a narrow explosion limit (16%-27%), making it safer than hydrogen (18.3%-59%). Therefore, ammonia is considered a highly promising zero-carbon hydrogen source and hydrogen storage intermediate.
[0004] The decomposition of ammonia to produce hydrogen is based on the chemical properties of ammonia. Under high temperature and with the aid of a catalyst, the nitrogen-hydrogen bonds within the ammonia molecule break, generating hydrogen and nitrogen (2NH3→3H2+N2). This reaction is endothermic and requires continuous heating, but the produced hydrogen is of high purity and free of harmful impurities. Traditional iron-based catalysts are low in cost but have relatively low activity, requiring high temperatures (above 800℃) to achieve good results. Nickel-based catalysts have higher activity and can promote the reaction at relatively lower temperatures (650℃-850℃), but are more expensive. In recent years, novel composite catalysts have combined different active components, integrating the advantages of each component and improving catalyst performance and lifespan. Copper-manganese composite catalysts, etc., are prone to chemical poisoning and physical structural degradation in sulfur-containing and water-containing environments, limiting their versatility. Therefore, it is necessary to develop a new catalyst with good catalytic activity, selectivity, stability, and low cost to catalyze the conversion of ammonia to hydrogen. Summary of the Invention
[0005] This invention provides a WO3-NiO / ZnO composite oxygen carrier with high activity, good hydrogen selectivity, and excellent stability, and gives a simple and feasible preparation method and its application in the oxidative dehydrogenation of ammonia to produce hydrogen.
[0006] The technical solution of this invention is as follows:
[0007] In a first aspect, a method for preparing the WO3-NiO / ZnO oxygen carrier is disclosed, comprising the following steps:
[0008] 1) Synthesis of ZnO support: ZnO was synthesized by coprecipitation method. Zinc acetate was dissolved in water, ammonia was added to adjust the pH to 8-9, stirred, filtered and washed, and then dried. After drying, ZnO was obtained by calcination at 500-650℃ for 5-8h.
[0009] 2) Preparation of NiO / ZnO: ZnO was ground to 100-200 μm and dispersed in water. Then, Ni(NO3)2·6H2O was added in a water bath at 80-90℃ with stirring. After stirring at room temperature for 2-3 h, urea was added as a precipitant. The mixture was reacted at 80-90℃ for 8-10 h. The resulting precipitate was aged at room temperature for 12-15 h, filtered, washed, and then dried. Finally, it was calcined in a muffle furnace at 500-550℃ for 2-3 h to obtain NiO / ZnO.
[0010] 3) Preparation of WO3-NiO / ZnO oxygen carrier: NiO / ZnO is dispersed in water, and then tungsten nitrate hexahydrate and urea are added as precipitants. The mixture is stirred in a water bath at 60-100℃ for 6-12 hours, precipitated at room temperature for 12-24 hours, filtered, washed, and dried. The resulting solid is ground to 400-500 μm and calcined in a tube furnace at 400-500℃ for 3-6 hours under argon or nitrogen conditions. The resulting precipitate is ground to 100-200 μm and then calcined again in a muffle furnace at 500-600℃ for 1-2 hours to obtain the target product WO3-NiO / ZnO oxygen carrier.
[0011] Preferably, the mass ratio of zinc acetate, Ni(NO3)2·6H2O, and tungsten nitrate hexahydrate is (10-30):(1-5):(0.1-0.6).
[0012] Preferably, the mass concentration of zinc acetate in step 1) is 100-300 g / L.
[0013] Preferably, in step 1), the mass concentration of ammonia is 25%, the stirring time is 12-16 hours, the washing is done with deionized water and ethanol, and the drying is done at 80-100°C for 24-36 hours.
[0014] Preferably, in step 2), the mass ratio of nickel nitrate hexahydrate to urea is (1-5):0.05.
[0015] Preferably, in step 2), the washing is performed three times with deionized water, and the drying is performed at 80-90℃ for 6-8 hours.
[0016] Preferably, in step 3), the mass ratio of tungsten nitrate hexahydrate to precipitant is (1-6):0.1.
[0017] Preferably, in step 3), the drying process is carried out at a temperature of 60-100℃ for 8-16 hours.
[0018] Secondly, the preparation method described above discloses the WO3-NiO / ZnO oxygen carrier.
[0019] Thirdly, the application of the WO3-NiO / ZnO oxygen carrier in the oxidative dehydrogenation of ammonia to produce hydrogen is disclosed, including the following steps:
[0020] a. Add WO3-NiO / ZnO oxygen carrier to a fixed-bed reactor and pretreat with nitrogen at a flow rate of 100-200 mL / min for 20-30 min. Set the preheater temperature to 100-400℃, the fixed-bed reactor reaction temperature to 200-500℃, and the reaction pressure to 0.3-1 MPa.
[0021] b. Introduce ammonia gas, setting the ammonia gas inlet flow rate to 30-40 mL / min, to obtain the gaseous product hydrogen gas;
[0022] c. After the reaction is complete, nitrogen gas is introduced to purge the remaining gas in the reactor. Oxygen gas is then introduced into the fixed bed reactor at a temperature of 300-450℃ to obtain WO3-NiO / ZnO oxygen carrier with restored lattice oxygen for use in the next experiment.
[0023] Compared with the prior art, the present invention has the following advantages:
[0024] 1. In this invention, NiO, as the main active component, can provide lattice oxygen and promote NH3 conversion; however, NiO alone is prone to over-oxidation. ZnO can improve NiO dispersion, stabilize the structure, regulate surface acidity and alkalinity, weaken the oxidizing ability of NiO, and improve the selectivity of H2, while also inhibiting carbon deposition or sintering caused by deep Ni reduction. WO3 can increase surface acidic sites and promote NH3 adsorption and activation; the multivalent state of tungsten (WO3→WO) 3-x WO3 can participate in redox reactions, and its moderate lattice oxygen mobility helps control the oxidation depth and inhibits the reduction of NiO to metallic Ni (avoiding deviation from the catalytic decomposition pathway of NH3). The acidic sites of WO3 and the weakly basic sites of NiO synergistically promote the dissociation of NH3, while ZnO, as a structural aid, enhances the oxygen transfer efficiency between NiO and WO3.
[0025] 2. This invention employs a stepwise precipitation and calcination process, resulting in uniform loading and strong bonding of each component. In particular, the inert atmosphere calcination combined with secondary air calcination effectively controls the valence state of WO3 and the surface properties of the carrier, optimizing oxygen migration capabilities.
[0026] 3. The oxygen carrier of the present invention has good cycle stability. After the oxidative dehydrogenation reaction, the oxygen carrier can be regenerated by simple oxygenation to restore its lattice oxygen reserves, showing good recyclability and potential for industrial application. Attached Figure Description
[0027] Figure 1 is a scanning electron microscope image of the catalyst prepared in Example 1 of this invention.
[0028] Figure 2 is a morphology image of the catalyst prepared in Example 1 of the present invention under a high magnification microscope.
[0029] Figure 3 is an XRD pattern of the catalyst prepared in Example 1 of this invention. Detailed Implementation
[0030] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions will be clearly and completely described below in conjunction with the embodiments of this invention.
[0031] Example 1
[0032] The preparation method of the WO3-NiO / ZnO oxygen carrier includes the following steps:
[0033] 1) Synthesis of ZnO support: ZnO was synthesized by coprecipitation method. 20g of zinc acetate was dissolved in 100mL of water, 25% ammonia was added to adjust the pH to 8, and the mixture was stirred for 15h. The mixture was filtered and washed with water and ethanol, then dried at 90℃ for 30h, and calcined at 600℃ for 6h to obtain ZnO.
[0034] 2) Preparation of NiO / ZnO: The ZnO prepared in step 1) was ground to 150 μm and dispersed in 100 mL of water. Then, 2 g of nickel nitrate hexahydrate Ni(NO3)2·6H2O was added under stirring in an 85 °C water bath. After stirring at room temperature for 2.5 h, 0.05 g of urea was added as a precipitant. The mixture was reacted at 85 °C for 9 h. The resulting precipitate was aged at room temperature for 13 h, filtered, washed three times with deionized water, and then dried at 85 °C for 7 h. Finally, it was calcined in a muffle furnace at 520 °C for 2.5 h to obtain NiO / ZnO.
[0035] 3) Preparation of WO3-NiO / ZnO oxygen carrier: The NiO / ZnO prepared in step 2) was dispersed in 100 mL of water, and then 0.3 g of tungsten nitrate hexahydrate and 0.01 g of urea were added as precipitants. The mixture was stirred in an 80 °C water bath for 10 h, precipitated at room temperature for 16 h, filtered, washed, and dried at 80 °C for 10 h. The resulting solid was ground to 450 μm and calcined in a tube furnace at 450 °C for 5 h under argon conditions. The resulting precipitate was ground to 150 μm and then calcined again in a muffle furnace at 550 °C for 1.5 h to obtain the target product WO3-NiO / ZnO oxygen carrier. The morphology of the oxygen carrier under a scanning electron microscope is shown in Figure 1, the morphology of the oxygen carrier under a high magnification microscope is shown in Figure 2, and the XRD test pattern is shown in Figure 3, which proves the successful synthesis of WO3-NiO / ZnO oxygen carrier.
[0036] The application of the WO3-NiO / ZnO oxygen carrier in the oxidative dehydrogenation of ammonia to produce hydrogen includes the following steps:
[0037] a. Add 1g of WO3-NiO / ZnO oxygen carrier to a fixed-bed reactor and pretreat with nitrogen at a flow rate of 150mL / min for 25min. The preheater temperature is set to 200℃, the fixed-bed reactor reaction temperature is set to 300℃, and the reaction pressure is set to 0.5MPa.
[0038] b. Introduce ammonia gas, setting the ammonia gas inlet flow rate to 35 mL / min, to obtain the gaseous product hydrogen gas;
[0039] c. After the reaction is complete, nitrogen gas is introduced to purge the remaining gas in the reactor. Oxygen gas is then introduced into the fixed bed reactor at a set temperature of 400℃ to obtain WO3-NiO / ZnO oxygen carrier with restored lattice oxygen, which will be used in the next experiment.
[0040] Example 2
[0041] The preparation method of the WO3-NiO / ZnO oxygen carrier includes the following steps:
[0042] 1) Synthesis of ZnO support: ZnO was synthesized by coprecipitation method. 10g of zinc acetate was dissolved in 100mL of water, 25% ammonia was added to adjust the pH to 8, and the mixture was stirred for 12h. The mixture was filtered and washed with water and ethanol, then dried at 80℃ for 36h, and calcined at 500℃ for 8h to obtain ZnO.
[0043] 2) Preparation of NiO / ZnO: The ZnO prepared in step 1) was ground to 100 μm and dispersed in 100 mL of water. Then, 1 g of nickel nitrate hexahydrate Ni(NO3)2·6H2O was added under stirring in an 80 °C water bath. After stirring at room temperature for 2 h, 0.05 g of urea was added as a precipitant. The mixture was reacted at 80 °C for 10 h. The resulting precipitate was aged at room temperature for 12 h, filtered, and washed three times with deionized water. Then, it was dried at 80 °C for 8 h. Finally, it was calcined in a muffle furnace at 500 °C for 3 h to obtain NiO / ZnO.
[0044] 3) Preparation of WO3-NiO / ZnO oxygen carrier: The NiO / ZnO prepared in step 2) was dispersed in 100 mL of water, and then 0.1 g of tungsten nitrate hexahydrate and 0.01 g of urea were added as precipitants. The mixture was stirred in a 60 °C water bath for 12 h, precipitated at room temperature for 12 h, filtered, washed, and dried at 60 °C for 16 h. The resulting solid was ground to 400 μm and calcined in a tube furnace at 400 °C for 6 h under nitrogen conditions. The resulting precipitate was ground to 100 μm and then calcined again in a muffle furnace at 500 °C for 2 h to obtain the target product WO3-NiO / ZnO oxygen carrier.
[0045] The application of the WO3-NiO / ZnO oxygen carrier in the oxidative dehydrogenation of ammonia to produce hydrogen includes the following steps:
[0046] a. Add 1g of WO3-NiO / ZnO oxygen carrier to a fixed-bed reactor and pretreat with nitrogen at a flow rate of 100mL / min for 30min. The preheater temperature is set to 100℃, the fixed-bed reactor reaction temperature is set to 200℃, and the reaction pressure is set to 0.3MPa.
[0047] b. Introduce ammonia gas, setting the ammonia gas inlet flow rate to 30 mL / min, to obtain the gaseous product hydrogen gas;
[0048] c. After the reaction is complete, nitrogen gas is introduced to purge the remaining gas in the reactor. Oxygen gas is then introduced into the fixed bed reactor at a set temperature of 300℃ to obtain WO3-NiO / ZnO oxygen carrier with restored lattice oxygen, which will be used in the next experiment.
[0049] Example 3
[0050] The preparation method of the WO3-NiO / ZnO oxygen carrier includes the following steps:
[0051] 1) Synthesis of ZnO support: ZnO was synthesized by coprecipitation method. 30g of zinc acetate was dissolved in 100mL of water, 25% ammonia was added to adjust the pH to 9, and the mixture was stirred for 16h. The mixture was filtered and washed with water and ethanol, then dried at 100℃ for 24h, and calcined at 650℃ for 5h to obtain ZnO.
[0052] 2) Preparation of NiO / ZnO: The ZnO prepared in step 1) was ground to 200 μm and dispersed in 100 mL of water. Then, 5 g of nickel nitrate hexahydrate Ni(NO3)2·6H2O was added in a 90 °C water bath with stirring. After stirring at room temperature for 3 h, 0.05 g of urea was added as a precipitant. The mixture was reacted at 90 °C for 8 h. The resulting precipitate was aged at room temperature for 15 h, filtered, washed three times with deionized water, and then dried at 90 °C for 6 h. Finally, it was calcined in a muffle furnace at 550 °C for 2 h to obtain NiO / ZnO.
[0053] 3) Preparation of WO3-NiO / ZnO oxygen carrier: The NiO / ZnO prepared in step 2) was dispersed in 100 mL of water, and then 0.6 g of tungsten nitrate hexahydrate and 0.01 g of urea were added as precipitants. The mixture was stirred in a 100 °C water bath for 6 h, precipitated at room temperature for 24 h, filtered, washed, and dried at 100 °C for 8 h. The resulting solid was ground to 500 μm and calcined in a tube furnace at 500 °C for 3 h under nitrogen conditions. The resulting precipitate was ground to 200 μm and then calcined again in a muffle furnace at 600 °C for 1 h to obtain the target product WO3-NiO / ZnO oxygen carrier.
[0054] The application of the WO3-NiO / ZnO oxygen carrier in the oxidative dehydrogenation of ammonia to produce hydrogen includes the following steps:
[0055] a. Add 1g of WO3-NiO / ZnO oxygen carrier to a fixed-bed reactor, pretreat with nitrogen at a flow rate of 200mL / min for 20min, set the preheater temperature to 400℃, set the fixed-bed reactor reaction temperature to 500℃, and set the reaction pressure to 1MPa.
[0056] b. Introduce ammonia gas, setting the ammonia gas inlet flow rate to 40 mL / min, to obtain the gaseous product hydrogen gas;
[0057] c. After the reaction is complete, nitrogen gas is introduced to purge the remaining gas in the reactor. Oxygen gas is then introduced into the fixed bed reactor at a set temperature of 450℃ to obtain WO3-NiO / ZnO oxygen carrier with restored lattice oxygen, which will be used in the next experiment.
[0058] Comparative Example 1
[0059] Unlike Example 1, this comparative oxygen carrier does not contain NiO, but the rest of the preparation methods and steps are the same as in Example 1.
[0060] Comparative Example 2
[0061] Unlike Example 1, this comparative oxygen carrier does not contain WO3, but the rest of the preparation methods and steps are the same as in Example 1.
[0062] Comparative Example 3
[0063] Unlike Example 1, step 3) in this comparative example does not include secondary calcination; the remaining preparation methods and steps are the same as in Example 1.
[0064] Comparative Example 4
[0065] Unlike Example 1, this comparative example first loads WO3 and then NiO. The specific preparation method includes the following steps:
[0066] 1) Step 1) is the same as step 1) in Example 1;
[0067] 2) Preparation of WO3 / ZnO: The ZnO prepared in step 1) was dispersed in 100 mL of water, and 0.3 g of tungsten nitrate hexahydrate and 0.01 g of urea were added as precipitants. The mixture was stirred in an 80 °C water bath for 10 h, precipitated at room temperature for 16 h, filtered, washed, and dried at 80 °C for 10 h. The resulting solid was ground to 450 μm and calcined in a tube furnace at 450 °C for 5 h under argon conditions. The resulting solid was ground to 150 μm to obtain WO3 / ZnO.
[0068] 3) Preparation of oxygen carrier: WO3 / ZnO was dispersed in 100mL of water, and 2g of Ni(NO3)2·6H2O was added under stirring in an 85℃ water bath. After stirring at room temperature for 2.5h, 0.05g of urea was added, and the reaction was carried out at 85℃ for 9h. After aging at room temperature for 13h, the mixture was filtered, washed, dried at 85℃ for 7h, and finally calcined in a muffle furnace at 520℃ for 2.5h to obtain the oxygen carrier.
[0069] The application of the WO3-NiO / ZnO oxygen carrier in the ammonia oxidative dehydrogenation to produce hydrogen is the same as in Example 1.
[0070] The oxygen carriers prepared in the examples and comparative examples were subjected to performance testing, and the test results are shown in Table 1.
[0071] Table 1 Catalyst performance test results
[0072]
[0073] As can be seen from Table 1, the catalyst prepared by this invention has an average specific surface area, suitable pore size, and high mechanical strength, which are more conducive to improving catalytic performance.
[0074] The oxygen carriers prepared in the above examples and comparative examples were used for the oxidative dehydrogenation of ammonia, and the test results are shown in Table 2.
[0075] NH3 conversion and H2 selectivity are calculated using the following formulas:
[0076] 0076] ;
[0077] .
[0078] Table 2 Performance Evaluation of Ammonia Decomposition for Hydrogen Production
[0079]
[0080] Comparative Example 1 (without NiO): NH3 conversion was extremely low, but H2 selectivity was high. This directly demonstrates that NiO is the main active source providing lattice oxygen and driving the oxidative dehydrogenation of NH3. The oxidizing power of ZnO and WO3 alone is far from sufficient for efficient conversion of NH3; the reaction remains at the initial stage, with unreacted NH3 as the main product, and the generated H2 primarily originating from a mild oxidation pathway.
[0081] Comparative Example 2 (without WO3): The NH3 conversion rate remained high, but the H2 selectivity decreased significantly. This confirms that the key role of WO3 is to regulate the reaction pathway and inhibit over-oxidation. The lack of acidic sites for WO3 may weaken the adsorption and activation of NH3. More importantly, the absence of WO3's mild redox cycle "buffering" effect on NiO's oxidation capacity makes the reaction more likely to produce H2O and NO. x The deep oxidation path is carried out.
[0082] Comparative Example 3 (without secondary calcination): The initial activity and selectivity were acceptable, but as shown in Table 1, the crushing strength was significantly lower. This indicates that secondary calcination is crucial for enhancing the structural stability and improving the mechanical strength of the material.
[0083] Comparative Example 4 (reverse loading): Its activity and selectivity were both lower than those of Example 1. This is because loading WO3 first and then NiO may make it difficult for NiO to fully interact with the ZnO support, resulting in a decrease in NiO dispersion and a reduction in active sites; at the same time, the interfacial synergistic effect between NiO and WO3 may also be weakened due to the different preparation order, thus affecting the overall catalytic performance.
[0084] For the oxygen carrier prepared in Example 1, after the reaction was completed, nitrogen was introduced to purge the gas in the reactor. Then, oxygen was introduced into the fixed bed. The fixed bed reactor was set to a temperature of 400°C for 3 hours. After that, it was cooled to room temperature for the next experiment. The oxygen carrier prepared in Example 1 was circulated 10 times. The cycling performance of the ammonia decomposition to hydrogen production was evaluated as shown in Table 3.
[0085] Table 3 Cyclic performance results
[0086]
[0087] In Example 1, after 10 cycles, the oxygen carrier showed only a small decrease in NH3 conversion and H2 selectivity. This demonstrates that the lattice oxygen in the oxygen carrier can be effectively restored through the oxygen regeneration step, and that the WO3-NiO / ZnO composite structure exhibits good thermal stability and anti-sintering ability, allowing the active sites to be maintained during multiple redox cycles.
[0088] Although the present invention has been described in detail by way of preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. The application of WO3-NiO / ZnO oxygen carrier in the oxidative dehydrogenation of ammonia to produce hydrogen, characterized in that, Includes the following steps: a. Add WO3-NiO / ZnO oxygen carrier to a fixed-bed reactor and pretreat with nitrogen at a flow rate of 100-200 mL / min for 20-30 min. Set the preheater temperature to 100-400℃, the fixed-bed reactor reaction temperature to 200-500℃, and the reaction pressure to 0.3-1 MPa. b. Introduce ammonia gas at a flow rate of 30-40 mL / min to obtain hydrogen as a gaseous product. c. After the reaction is complete, introduce nitrogen gas to purge any remaining gas from the reactor. Continue to introduce oxygen into the fixed-bed reactor. A WO3-NiO / ZnO oxygen carrier with restored lattice oxygen was obtained by setting the temperature to 300-450℃ for use in the next experiment. The preparation method of the WO3-NiO / ZnO oxygen carrier includes the following steps: 1) Synthesis of ZnO support: ZnO is synthesized by co-precipitation method. Zinc acetate is dissolved in water, ammonia is added to adjust the pH to 8-9, stirred, filtered and washed, then dried, and calcined at 500-650℃ for 5-8h to obtain ZnO; 2) Preparation of NiO / ZnO: ZnO is ground to 100-200μm and dispersed in water, then calcined at 8℃ for 5-8h. Ni(NO3)2·6H2O was added to a water bath at 0-90℃ with stirring. After stirring at room temperature for 2-3 hours, urea was added as a precipitant, and the mixture was reacted at 80-90℃ for 8-10 hours. The resulting precipitate was aged at room temperature for 12-15 hours, filtered, washed, and then dried. Finally, it was calcined in a muffle furnace at 500-550℃ for 2-3 hours to obtain NiO / ZnO. 3) Preparation of WO3-NiO / ZnO oxygen carrier: NiO / ZnO was dispersed in water, and then tungsten nitrate hexahydrate was added to it. Urea was added as a precipitant, and the mixture was reacted at 60-100℃. Stir in a water bath at ℃ for 6-12 hours, precipitate at room temperature for 12-24 hours, filter, wash, dry, grind the obtained solid to 400-500 μm, calcine in a tube furnace at 400-500℃ for 3-6 hours under argon or nitrogen conditions, grind the obtained precipitate to 100-200 μm, and calcine again in a muffle furnace at 500-600℃ for 1-2 hours to obtain the target product WO3-NiO / ZnO oxygen carrier; the mass ratio of zinc acetate, Ni(NO3)2·6H2O, and tungsten nitrate hexahydrate is (10-30):(1-5):(0.1-0.6).
2. The application of the WO3-NiO / ZnO oxygen carrier according to claim 1 in the oxidative dehydrogenation of ammonia to produce hydrogen, characterized in that, In step 1), the mass concentration of zinc acetate is 100-300 g / L.
3. The application of the WO3-NiO / ZnO oxygen carrier according to claim 1 in the oxidative dehydrogenation of ammonia to produce hydrogen, characterized in that, In step 1), the ammonia concentration is 25%, the stirring time is 12-16 hours, the washing is done with deionized water and ethanol, and the drying is done at 80-100℃ for 24-36 hours.
4. The application of the WO3-NiO / ZnO oxygen carrier according to claim 1 in the oxidative dehydrogenation of ammonia to produce hydrogen, characterized in that, In step 2), the mass ratio of nickel nitrate hexahydrate to urea is (1-5):0.
05.
5. The application of the WO3-NiO / ZnO oxygen carrier according to claim 1 in the oxidative dehydrogenation of ammonia to produce hydrogen, characterized in that, In step 2), the washing is performed three times with deionized water, and the drying is performed at 80-90℃ for 6-8 hours.
6. The application of the WO3-NiO / ZnO oxygen carrier according to claim 1 in the oxidative dehydrogenation of ammonia to produce hydrogen, characterized in that, In step 3), the mass ratio of tungsten nitrate hexahydrate to precipitant is (1-6):0.
1.
7. The application of the WO3-NiO / ZnO oxygen carrier according to claim 1 in the oxidative dehydrogenation of ammonia to produce hydrogen, characterized in that, In step 3), the drying process involves drying at 60-100℃ for 8-16 hours.