A supported catalyst, its preparation method and use

Abstract

This invention provides a supported catalyst, its preparation method, and its application. The supported catalyst is a ZrO2-based supported catalyst with Fe nanoparticles supported on ZrO2 to form a plate-like structure. The specific preparation method is as follows: ferric nitrate, zirconium nitrate, and citric acid are mixed and dissolved in deionized water, stirred until homogeneous, forming a mixed solution; the mixed solution is placed in a heated stirrer, and nitric acid and ethylenediamine are added during stirring. After thorough stirring, ammonia water is added to adjust the pH to neutral, and then the sample is heated and dried until it becomes a gel; the gel sample is dried and aged in a blower dryer, then annealed in a tube furnace under an argon atmosphere, and finally calcined in a muffle furnace. The supported catalyst prepared by this invention can be used for the thermal catalytic cracking of formic acid to produce carbon monoxide. The preparation process of this supported catalyst is simple, the preparation temperature is low, the variables are easily controlled, it can be produced on a large scale, it does not require water washing, and it reduces environmental pollution.

Description

Technical Field

[0001] This invention relates to the fields of nanomaterials and thermocatalysis, specifically to a supported catalyst, its preparation method, and its application. Background Technology

[0002] Supported catalysts are catalytic systems in which one catalyst is supported on another material to form a composite catalyst. Supported catalysts can be inorganic particles, porous materials, organic polymers, metals or their oxides, etc., while the catalyst itself is usually a metal complex. Due to their high efficiency, stability, and reusability, supported catalysts have been widely used in chemical reactions. Furthermore, supported catalysts can reduce the amount of catalyst used and decrease environmental pollution.

[0003] Carbon monoxide (CO) is a colorless and odorless gas. Initially, it was primarily considered a hazardous gas; however, modern scientific research has provided us with a deeper understanding of it. Carbon monoxide occupies a central position in organic synthesis, serving as a key precursor for many basic chemicals and intermediates. Formic acid is generally considered a potential hydrogen storage molecule, but depending on the catalyst, its catalytic cracking can occur via two pathways: dehydration to CO and H₂O on an acidic catalyst, or dehydrogenation to H₂ and CO₂ on a metal or basic catalyst. In recent years, most research on the catalytic cracking of formic acid has focused on how to efficiently produce hydrogen, while research on dehydration to CO is relatively limited. Research on catalysts for the cracking of formic acid to produce CO mainly focuses on two types of catalysts: one based on ZrO₂ and the other on TiO₂. Catalysts with different substrates exhibit different properties and application values. This invention utilizes the first pathway to prepare a highly selective iron-based catalyst for the catalytic cracking and dehydration of formic acid to produce high-purity CO. Summary of the Invention

[0004] The purpose of this invention is to provide a supported catalyst, its preparation method and application. This catalyst can be used for the thermal catalytic cracking of formic acid to produce carbon monoxide, and it is targeted, efficient and stable.

[0005] This invention is implemented as follows:

[0006] The supported catalyst provided by this invention consists of Fe nanoparticles supported on ZrO2 to form a sheet-like Fe structure. NP / ZrO2 supported catalyst.

[0007] like Figure 1 As shown, the method for preparing the supported catalyst provided by the present invention includes the following steps:

[0008] (1) Mix ferric nitrate, zirconium nitrate and citric acid in deionized water and stir until homogeneous to form a mixed solution.

[0009] (2) Place the mixed solution from step (1) into a multi-head magnetic heating stirrer and stir it. During the stirring process, add 1.2 mL of HNO3 and 0.6 mL of C2H8N2 dropwise. After stirring thoroughly, add NH3·H2O dropwise until the pH of the solution is neutral. Heat to 80°C and dry until it becomes a viscous gel.

[0010] (3) Place the viscous gel in step (2) into a blower dryer and dry for 24 hours.

[0011] (4) After drying in step (3), the sample is placed in the quartz tube of the tube furnace, argon is introduced for 1 hour to purge the air, and the temperature is raised to 400°C at a rate of 10°C / min under argon atmosphere and kept at that temperature for 4 hours. After cooling to room temperature, the sample is taken out and placed in a muffle furnace and calcined at 400°C for 4 hours.

[0012] This invention discloses a supported catalyst prepared by the above method. The obtained supported catalyst has adjustable composition, uniform element distribution, and a nanosheet morphology with a thickness of about 1 to 30 nm.

[0013] This invention further discloses Fe NP The application of ZrO2 supported catalysts in the photo-driven thermocatalytic cracking of formic acid to produce carbon monoxide involves vaporizing formic acid and loading it into the reaction device with argon gas. The performance of formic acid cracking to produce carbon monoxide is then tested by photo-driven heating.

[0014] This invention addresses the needs of photo-driven thermocatalytic formic acid pyrolysis for carbon monoxide production. It proposes a novel method for preparing a catalyst for this process. Specifically, citric acid is used as a template, and a viscous gel is obtained through stirring, heating, and drying. This gel is then annealed under an argon atmosphere and subsequently calcined to obtain a supported catalyst. This catalyst is highly targeted, efficient, and stable for the thermocatalytic pyrolysis of formic acid to produce carbon monoxide.

[0015] The present invention has the following beneficial effects:

[0016] (1) The method for preparing supported catalysts in this invention has a maximum temperature of only 400℃, which greatly reduces the preparation temperature of nanoparticle supported catalysts.

[0017] (2) The equipment for preparing supported catalysts in this invention only requires a multi-head magnetic heating stirrer, a tube furnace, and a muffle furnace. Compared with other high-temperature smelting equipment for preparing supported catalysts, it has the advantages of simple equipment and low cost.

[0018] (3) Fe in this inventionNP The preparation process of ZrO2 supported catalysts is simple, the variables are easy to control, and it can be produced on a large scale without the need for water washing, thus reducing environmental pollution. Attached Figure Description

[0019] Figure 1 This is a flowchart of the preparation method of the present invention.

[0020] Figure 2 The Fe obtained in the examples NP XRD pattern of ZrO2 catalyst.

[0021] Figure 3 The Fe obtained in the examples NP Scanning electron microscope (SEM) image of the ZrO2 catalyst.

[0022] Figure 4 The Fe obtained in the examples NP Transmission electron microscopy (TEM) image of the ZrO2 catalyst.

[0023] Figure 5 The Fe obtained in the examples NP / Performance test diagram of ZrO2 thermal catalytic formic acid cracking to produce carbon monoxide.

[0024] Figure 6 Fe in the examples NP / Stability test diagram of the thermal catalytic cracking of formic acid to produce carbon monoxide using ZrO2.

[0025] Figure 7 Fe in the examples NP / Performance test diagram of ZrO2-driven thermocatalytic formic acid cracking to produce carbon monoxide. Detailed Implementation

[0026] This invention was completed with the support of the "Hebei Provincial Natural Science Foundation General Program B2023204034" and the "Hebei Provincial Department of Education Science and Technology Research Youth Program QN2022059".

[0027] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0028] Example

[0029] Combination Figure 1 The specific method for preparing the supported catalyst provided in this embodiment is as follows:

[0030] 1) At room temperature, add about 5 mL of deionized water to a clean 50 mL measuring beaker. Weigh 2.5 g of C6H8O7·H2O, 1 g of Zr(NO3)4·5H2O and 0.03 g of Fe(NO3)3·9H2O using a four-position balance and add them to the beaker to form a mixed solution.

[0031] 2) Place the mixed solution from step 1) into a multi-head magnetic stirrer and stir. During the stirring process, add 1.2 mL of HNO3 and 0.6 mL of C2H8N2 dropwise. After stirring evenly, add NH3·H2O dropwise until the pH is neutral. Heat the multi-head magnetic stirrer to 80°C and stir and dry for 1 hour until a viscous gel-like substance is formed.

[0032] 3) Place the viscous gel from step 2) into a quartz boat and dry and age it at 80°C in a blower dryer for 24 hours.

[0033] 4) Transfer the aged sample from step 3) into a quartz tube in a tube furnace, purge with argon gas for 1 hour to purge air, and raise the temperature to 400°C at a rate of 10°C / min under an argon atmosphere and hold for 4 hours. When the temperature of the tube furnace reaches 400°C, the aged catalyst is instantly annealed, and then held at that temperature for 4 hours until the temperature drops to room temperature before being removed.

[0034] 5) The annealed sample from step 4) was placed in a muffle furnace and calcined at 400°C for 4 hours to obtain a catalyst of Fe nanoparticles supported on ZrO2, denoted as Fe. NP / ZrO2.

[0035] The Fe prepared in this embodiment NP XRD tests were performed on the ZrO2 supported catalyst, and the results are as follows: Figure 2 As shown. Figure 2 The image also shows the XRD patterns of the purchased ZrO2 and a standard ZrO2 (cubic) card. Fe was observed from the XRD patterns. NP The diffraction peaks of the ZrO2 nanosheet catalyst were all ZrO2 diffraction peaks, and no diffraction peaks of iron-containing compounds such as iron oxide and iron(II,III) oxide were found, indicating that Fe is highly dispersed in ZrO2.

[0036] The Fe prepared in this embodiment NP Scanning electron microscopy (SEM) analysis was performed on the ZrO2 supported catalyst, and the results are as follows: Figure 3 As shown. By Figure 3 It can be seen that Fe NP The ZrO2 catalyst has a two-dimensional nanosheet morphology with a smooth and flat surface.

[0037] The Fe prepared in this embodiment NPTransmission electron microscopy (TEM) analysis was performed on the ZrO2-supported catalyst, and the results are as follows: Figure 4 As shown. Figure 4 (a) shows the microstructure, indicating that Fe NP The ZrO2 catalyst is in the form of two-dimensional nanosheets, which is corroborated by the SEM image results; from Figure 4 (b) It can be seen that Fe NP In the ZrO2 catalyst, Fe, Zr, and O elements are uniformly distributed, and there is no element agglomeration. Figure 4 (c) clearly shows lattice fringes, corresponding to the ZrO2(111) crystal plane with a lattice spacing of 0.290 nm.

[0038] The Fe prepared using this example NP Thermocatalytic cracking of formic acid to carbon monoxide using a ZrO2 supported catalyst yielded the following test results: Figure 5 As shown, at the same time, Figure 5 The paper also provides a comparison chart of the yields of carbon monoxide produced by the thermocatalytic cracking of formic acid using commercially available ZrO2 catalyst. From... Figure 5 It can be seen from this that at 250℃, Fe NP The CO yield of the ZrO2 catalyst reached as high as 117.4 mmol g. -1 h -1 It surpasses the 105.8 mmol g of ZrO2 catalyst. -1 h -1 The data demonstrates the high efficiency of the Fe-supported catalyst in promoting formic acid pyrolysis, which may be attributed to the changes in the structure and morphology of ZrO2 caused by the intercalation of Fe3+.

[0039] Figure 6 The Fe prepared in the example NP The graph shows the performance and stability test of the ZrO2 supported catalyst in the thermal catalytic cracking of formic acid to produce carbon monoxide. A stability test was conducted at 200℃ for 8 hours. The graph shows that during the 8-hour stability test, the CO yield decreased from 14 mmol / g. -1 h -1 Slowly decreased to 11 mmol g -1 h -1 Around 100%, there was no significant decrease in CO yield, indicating that Fe... NP / ZrO2 does not exhibit catalyst deactivation during testing.

[0040] Figure 7 The Fe prepared in the example NPThe test diagram shows the photo-driven thermocatalytic cracking of formic acid to produce carbon monoxide using a ZrO2 supported catalyst. Specifically, formic acid was vaporized and introduced into the reaction device via argon gas. The performance of formic acid cracking to produce carbon monoxide was tested by photo-driven heating. Figure 7 (a) shows that the temperatures reached in the device under different light intensities are sufficient to drive the thermal catalysis of formic acid. Figure 7 (b) The displayed light intensity reaches 0.15 kW·m -2 Formic acid begins its cleavage reaction, with an initial carbon monoxide yield of 4.31 mmol·g. -1 h -1 As the light intensity increases to 0.25 kW·m -2 and 0.3kW·m -2 The carbon monoxide yield increased to 23.16 mmol·g. -1 h -1 and 36.33 mmol·g -1 h -1 . Figure 7 (c) shows Fe NP The CO selectivity of ZrO2 remained high under both thermocatalytic and photothermal catalytic conditions, at 0.3 kW·m⁻¹. -2 Under certain light intensity, the CO selectivity exceeds 99.3%, meeting the requirements for high-purity carbon monoxide gas in industrial applications. Figure 7 (d) shows the test results for photothermal catalysis stability. Similar to thermocatalysis, photothermal catalysis also exhibits high stability. These results indicate that Fe... NP / ZrO2 exhibits excellent performance in photothermal catalytic formic acid cracking and has the potential for the production of high-purity carbon monoxide.

[0041] This invention utilizes zirconium nitrate (Zr(NO3)4·5H2O) as a support and metal salt as a precursor to prepare Fe nanoparticles supported on ZrO2 via a sol-gel method. NP / ZrO2 supported catalyst. Utilizing the Fe prepared in the embodiments of this invention... NP Comparative experimental results of the / ZrO2 supported catalyst for the thermal catalytic cracking of formic acid to produce carbon monoxide show that it outperforms the ZrO2 catalyst; indicating that Fe nanoparticles supported on ZrO2 form Fe... NP The high efficiency and sustainability of ZrO2 supported catalysts. The preparation method of the supported catalyst provided by this invention has the advantages of low preparation temperature, targeted application, simplicity, simple equipment, and environmental friendliness, providing a new approach for the application of supported catalysts in fields such as photo-driven thermocatalysis.

[0042] In summary, this invention discloses a method for preparing supported nanocatalysts using citric acid as a template, which is used in a photo-driven thermocatalytic formic acid pyrolysis process to produce carbon monoxide. The method demonstrates its specificity and high efficiency, providing a new reference for the formic acid pyrolysis process to produce carbon monoxide.

[0043] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. The application of a supported catalyst in the thermocatalytic cracking of formic acid to produce carbon monoxide, characterized in that, The supported catalyst is a ZrO2-based supported catalyst in which Fe nanoparticles are supported on ZrO2 to form a sheet-like structure. The preparation method of the supported catalyst includes the following steps: a. Mix ferric nitrate, zirconium nitrate and citric acid and dissolve in deionized water, stir well to form a mixed solution; b. Place the mixed solution from step a into a multi-head magnetic heating stirrer and stir. During the stirring process, add HNO3 and C2H8N2 dropwise. After stirring thoroughly, add NH3·H2O dropwise until the pH of the solution is neutral. Heat the multi-head magnetic heating stirrer to 80 ℃ and stir to dry until a viscous gel is formed. c. Place the viscous gelatinous substance from step b into a blower dryer for drying and aging; d. Transfer the dried and aged sample into the quartz tube of the tube furnace, introduce argon gas into the quartz tube, heat it to 400℃, keep it at that temperature for 4 hours, and take it out after it cools down to room temperature. e. Place the sample obtained in step d in a muffle furnace and calcine it at 400℃ for 4h to obtain a supported catalyst with Fe nanoparticles supported on ZrO2.

2. The application according to claim 1, characterized in that, The heating rate in step d is 10℃ / min.

3. The application according to claim 1, characterized in that, In step c, the drying and aging temperature is 80℃ and the time is 24h.

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