A catalyst for the reduction of carbon dioxide to carbon monoxide with water, its preparation method and application
By loading palladium onto triazine-based carbon nitride to prepare a supported catalyst Pd/PTI, the problems of low stability and activity of traditional catalysts were solved, and a highly efficient carbon dioxide to carbon monoxide reaction was achieved with high selectivity and stability.
Patent Information
- Application Number
- CN202311815024.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-27
- Publication Date
- 2026-01-30
- Estimated Expiration
- 2043-12-27
AI Technical Summary
Traditional carbon nitride-based catalysts suffer from poor stability, low activity, and low selectivity in the process of catalyzing the reaction of carbon dioxide with water to produce carbon monoxide. Furthermore, traditional synthesis methods result in low crystallinity.
A small amount of the noble metal palladium (Pd) was supported on triazine-based crystalline carbon nitride (PTI) to prepare a supported catalyst Pd/PTI via molten salt method and sodium borohydride reduction method, thereby improving the catalyst's activity and stability.
It significantly improves the reaction efficiency and selectivity of carbon dioxide to carbon monoxide by adding water, and the stability and activity of the catalyst are significantly enhanced. The synthesis method is simple and the yield is considerable.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of carbon dioxide conversion, and particularly relates to a supported catalyst for promoting reduction of carbon dioxide to carbon monoxide with water. BACKGROUND
[0002] Since the first industrial revolution, with the exploitation and use of fossil energy, environmental problems caused by large-scale emission of greenhouse gases have become increasingly apparent. CO2 is a major member of greenhouse gases. The latest "Greenhouse Gas Bulletin" released by the World Meteorological Organization shows that the global CO2 abundance reached 415.7 ± 0.2 ppm in 2021. With the year-by-year increase in carbon emissions, climate change has attracted the attention of countries around the world. This linear economic model from fossil to CO2 is causing global warming, rising sea levels, ocean acidification, extreme weather, species extinction and food shortages. Developing efficient decarbonization technologies to capture, store and utilize CO2 can alleviate these problems. Catalytic conversion of CO2 is an important way to achieve resource utilization of CO2 and alleviate climate and environmental problems. How to develop efficient CO2 reaction systems and explore suitable photocatalysts is a difficult problem to be faced in realizing photocatalytic CO2 reduction. Researchers are committed to the resource utilization of carbon dioxide, which not only can reduce its concentration in the atmosphere, but also can obtain other high-value energy materials, which has important significance in the development of new energy and environmental pollution control. Among the many products of carbon dioxide reduction, carbon monoxide has important significance. It is not only an important fuel, but also an important intermediate molecule for producing multi-carbon hydrocarbons.
[0003] Carbon nitride-based catalysts have been proven to be able to catalyze the reduction of carbon dioxide to carbon monoxide. However, the synthesis of carbon nitride using traditional thermal polymerization methods is not complete, and the crystallinity is low, which leads to low overall efficiency of photocatalytic reduction of carbon dioxide to carbon monoxide. At the same time, traditional carbon nitride-based catalysts also have problems such as low selectivity for carbon monoxide and poor stability. Triazine-based crystalline carbon nitride (PTI) greatly reduces the structural defects of the catalyst, greatly promotes the separation and transmission of photo-generated charges, and thus realizes efficient driving of the photocatalytic reduction of carbon dioxide to carbon monoxide reaction. Adding a small amount of noble metal as a cocatalyst on the surface of carbon nitride is one of the effective strategies to improve its performance in catalyzing the reduction of carbon dioxide to carbon monoxide. This is because noble metals can promote the activation of carbon dioxide and provide catalytic active sites for the reaction, thereby improving the reaction activity and selectivity. In view of the above problems, we use the molten salt method to prepare triazine-based crystalline carbon nitride (PTI) after multiple calcination and washing, and load metal Pd on PTI by sodium borohydride reduction method, to prepare a supported Pd / PTI catalyst with high activity, high selectivity and stability. SUMMARY
[0004] The present application aims to provide a supported catalyst for synthesizing carbon monoxide from carbon dioxide and water, which has high activity and stability.
[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:
[0006] A supported catalyst for synthesizing carbon monoxide from carbon dioxide and water is prepared by introducing Pd as a cocatalyst into triazine-based crystalline phase carbon nitride (PTI) to obtain the supported catalyst Pd / PTI. The optimal loading amount of Pd is about 2 wt%, and the loading amount is controllable.
[0007] The preparation method of the supported catalyst comprises the following steps:
[0008] (1) Triazine-based crystalline phase carbon nitride (PTI) is prepared by a molten salt method.
[0009] (2) The Pd / PTI supported catalyst is synthesized by a sodium borohydride reduction method.
[0010] The specific steps are as follows:
[0011] (1) 1 g of dicyandiamide, 3.5 g of sodium chloride and 6.5 g of lithium chloride are uniformly ground in a glove box, and the mixture is placed in an ampoule and calcined at 400 ℃, 5 ℃ / min -1 , under a nitrogen atmosphere for 4 h. The ampoule is taken out and vacuum sealed, and then calcined at 550 ℃, 5 ℃ / min -1 , under an air atmosphere for 12 h. After taking out, the mixture is filtered and washed, and dried to obtain triazine-based crystalline phase carbon nitride (PTI).
[0012] (2) 100 mg of PTI is uniformly dispersed in deionized water, 200 μl of 10 mg / ml palladium chloride solution is added, and after stirring and adsorbing, 1 ml of 100 mg / ml sodium borohydride solution is added and reduced under stirring for half an hour. After washing and drying, the catalyst Pd / PTI is obtained.
[0013] The obtained supported catalyst can promote the reaction of synthesizing carbon monoxide from carbon dioxide and water.
[0014] The present application has the following remarkable effects:
[0015] (1) The present application loads Pd on triazine-based crystalline phase carbon nitride (PTI), promotes the activation and dissociation of carbon dioxide, and can significantly improve the efficiency of the catalytic reaction.
[0016] (2) The present application can effectively inhibit the recombination of photo-generated charges in the bulk phase of the catalyst, and improve the activity and selectivity of the catalyst.
[0017] (3) The present application is simple and easy to operate, has high carbon monoxide selectivity, and has great application potential. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 XRD patterns of PTI and Pd / PTI.
[0019] Figure 2 SEM pictures of PTI and Pd / PTI.
[0020] Figure 3 Activity comparison chart of PTI and Pd / PTI in catalyzing carbon dioxide and water to produce carbon monoxide.
[0021] Figure 4 XRD patterns of Pd / PTI before and after reaction. DETAILED DESCRIPTION
[0022] In order to make the content of the present application more convenient to understand, the technical solutions of the present application will be further described below in combination with specific embodiments, but the present application is not limited thereto.
[0023] Example 1 Preparation of triazine-based crystalline phase carbon nitride (PTI)
[0024] Grind 1 g of dicyandiamide, 3.5 g of sodium chloride and 6.5 g of lithium chloride uniformly in a glove box, place the mixture in an ampoule, and calcine at 400 ℃, 5 ℃ min -1 , under nitrogen atmosphere for 4 h, take out the ampoule and vacuum seal it, and then calcine at 550 ℃, 5 ℃ min -1 , under air atmosphere for 12 h, take out and filter wash the mixture, and dry to obtain triazine-based crystalline phase carbon nitride (PTI).
[0025] Example 2 Preparation of Pd / PTI supported catalyst
[0026] Disperse 100 mg of PTI uniformly in deionized water, add 200 μl of 10 mg / ml palladium chloride solution, stir and adsorb, then add 1 ml of 100 mg / ml sodium borohydride solution and reduce under stirring for half an hour, and then wash and dry to obtain the catalyst Pd / PTI.
[0027] Example 3: Evaluation of the activity of Pd / PTI carbon dioxide to carbon monoxide production via water addition
[0028] The efficiency evaluation experiment for the reaction of carbon dioxide and water to produce carbon monoxide using the Pd / PTI supported catalyst obtained in Example 2 was conducted in a transparent quartz reactor. The yields of CO and CH4 were detected using an Agilent 8890 gas chromatograph. The experimental procedure was as follows: 20 mg of catalyst was placed in the transparent quartz reactor, 200 μl of H2O was added, and high-purity CO2 gas was introduced into the reactor to completely remove air. The reaction was carried out using a 300 W xenon lamp as the light source.
[0029] Figure 1 The XRD patterns are for PTI and Pd / PTI. For example... Figure 1 As shown, the XRD pattern of the Pd / PTI supported catalyst contains all the characteristic peaks of PTI. The characteristic peaks of Pd are not shown in the pattern, mainly due to the low content and small particle size of Pd.
[0030] Figure 2 SEM images of PTI and Pd / PTI. From Figure 2 As can be seen in Figure a, pure PTI is a solid hexagonal prism. From... Figure 2 As can be seen in Figure b, the catalyst retains its solid hexagonal prism structure even after Pd loading.
[0031] Figure 3 A comparison of the activity of PTI and Pd / PTI in the production of carbon monoxide from carbon dioxide by adding water. From Figure 3 As can be seen, compared with pure PTI, the Pd / PTI supported catalyst can significantly improve the efficiency and selectivity of carbon monoxide production from carbon dioxide via water addition. This is mainly because Pd can promote CO2 activation, thereby improving the efficiency of selective reduction of carbon dioxide to carbon monoxide.
[0032] Figure 4 The XRD patterns of Pd / PTI before and after the catalytic reaction are shown. Comparison of the XRD patterns before and after the reaction reveals that the supported catalyst did not undergo significant changes compared to before the reaction, and no impurity peaks appeared, indicating the stability of the Pd / PTI catalyst.
[0033] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.
Claims
1. Use of a supported catalyst Pd / PTI in the reduction of carbon dioxide with water to carbon monoxide, characterized in that: The preparation method of the supported catalyst Pd / PTI is as follows: triazine-based crystalline phase carbon nitride PTI is prepared by a molten salt method through multi-step calcination and washing, and metal Pd is loaded on the PTI by a sodium borohydride reduction method to prepare the supported catalyst Pd / PTI.
2. Use according to claim 1, characterized in that: The loading amount of Pd on the PTI is controlled by the input amount of Pd precursor, and the loading amount is 0 to 3 wt%.
3. Use according to claim 1, characterized in that: The specific preparation steps of the supported catalyst Pd / PTI are as follows: (1) 1 g of dicyandiamide, 3.5 g of sodium chloride and 6.5 g of lithium chloride are uniformly ground in a glove box, the mixture is placed in an ampoule and calcined at 400 DEG C in a nitrogen atmosphere, the ampoule is taken out and vacuum sealed, and then calcined at 550 DEG C in an air atmosphere, after the reaction is completed, the mixture is filtered and washed, and dried to obtain triazine-based crystalline phase carbon nitride PTI; (2) 100 mg of PTI is dispersed in deionized water, 200 μl of 10 mg / ml palladium chloride solution is added, after stirring, 1 ml of 100 mg / ml sodium borohydride solution is added, and the reduction is carried out for half an hour under stirring, and after washing and drying, the catalyst Pd / PTI is obtained.