A composition, a method of preparation and use thereof in the catalysis field

Abstract

The application belongs to the technical field of catalyst research and development, and particularly relates to a composition, a preparation method and application thereof in the field of catalysis. The application provides a composition, raw materials of the composition comprising: an active component, an auxiliary agent and a carrier, the active component being a copper salt, and the carrier being aluminum nitride. The application also provides a preparation method of the composition, and application of the product obtained by the preparation method in a formaldehyde hydration dehydrogenation catalyst. In the technical scheme, the aluminum nitride carrier is used, the stability of the catalyst in a water-containing environment is effectively improved, secondly, most of the hydrated formaldehyde can be catalytically reformed into H2 and CO2 without additional introduction of an alkaline medium, and the generation of byproduct formic acid is effectively inhibited, and thirdly, the catalytic dehydrogenation can be carried out under heating conditions, and the reaction efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of catalyst research and development technology, and particularly relates to a composition, preparation method and its application in the field of catalysis. Background Technology

[0002] In recent years, the formaldehyde dehydrogenation reaction (HCHO + H2O → H2 + CO2) has attracted great interest due to the high theoretical hydrogen weight percentage (8.4 wt%) of formaldehyde aqueous solution. It can be used for hydrogen production from formaldehyde in aqueous phase and also provides a potential purification method for wastewater containing formaldehyde impurities, thus gaining widespread attention in the industry. Copper-based catalysts are more suitable for industrial application in formaldehyde dehydrogenation reactions due to their high catalytic activity, low cost, and easy availability. However, current research on the application of formaldehyde dehydrogenation in formaldehyde aqueous phase hydrogen production is still in the preliminary exploratory stage. Most reported patents require the reaction to be carried out under strongly alkaline conditions. Furthermore, the high reactivity of formaldehyde leads to numerous side reactions, especially the Cannizzaro disproportionation reaction under alkaline conditions, which generates methanol and formate, resulting in low efficiency in formaldehyde aqueous phase hydrogen production. The large amount of formate generated and the unreacted strongly alkaline medium also increase subsequent treatment costs and the risk of secondary pollution to the aquatic environment. Furthermore, in existing technologies, some heterogeneous catalyst supports, such as Al2O3, undergo hydration under high temperature and steam conditions, leading to catalyst pulverization and deactivation. In reaction systems with high water content, catalyst particles are prone to growth, leaching, and oxidation, resulting in reduced catalyst conversion and selectivity, and even shortened lifespan, which is detrimental to industrial production.

[0003] The aforementioned shortcomings impose numerous limitations on the industrial application of formaldehyde-based aqueous hydrogen production, particularly posing a significant challenge to the clean treatment of formaldehyde byproducts. In particular, the introduction of large amounts of alkaline media and the improvement of the hydrothermal stability of the catalyst in high-water-content reaction systems are critical issues that urgently need to be addressed.

[0004] Additionally, it should be noted that the high reactivity of formaldehyde in an alkaline-free medium can also lead to the Cannizaro disproportionation side reaction, producing formic acid. Due to the lack of a base for neutralization, the formic acid produced can cause catalyst deactivation and corrosion of metal reaction equipment.

[0005] In the clean treatment of numerous formaldehyde byproducts, catalytic removal of formaldehyde from crude paraformaldehyde is of great significance for reducing the refining cost of paraformaldehyde. Paraformaldehyde is an organic compound mainly used as an intermediate in engineering plastics such as polyoxymethylene (POM) and other chemicals. It can also be used as a disinfectant and a colorless, flameless fuel. Crude paraformaldehyde contains formaldehyde, which is difficult to remove by distillation during the refining process and readily self-polymerizes or forms formic acid, clogging and corroding equipment. Therefore, it requires necessary refining treatment.

[0006] Therefore, developing a composition, preparation method, and its application in the field of catalysis to address the technical defects of existing technologies, such as easy deactivation, low reaction efficiency, and inhibition of formic acid formation, has become an urgent problem for those skilled in the art. Summary of the Invention

[0007] Therefore, it is necessary to address the technical shortcomings of copper-based catalysts used for formaldehyde dehydrogenation in the prior art, such as easy deactivation, low reaction efficiency, and easy pollution, and to provide a composition, preparation method, and its application in the field of catalysis.

[0008] The present invention provides a composition comprising, wherein the raw materials of the composition include: an active component, an auxiliary agent and a carrier, wherein the active component is a copper salt and the carrier is aluminum nitride.

[0009] In one embodiment, the raw materials of the composition, by weight, include: 10-30 parts of active ingredient, 5-10 parts of additive, and 20-40 parts of carrier.

[0010] In one embodiment, the particle size of the carrier is 40 nm to 50 μm.

[0011] In one embodiment, the copper salt is selected from any one or more of copper nitrate, copper acetate, and copper sulfate.

[0012] In one embodiment, the additive is selected from any one or more salt solutions containing Zn, Zr, Ce, and Ni.

[0013] The present invention also provides a method for preparing a composition comprising any one of the above-described embodiments, wherein the preparation method comprises:

[0014] Step 1: The active component and additives are dissolved in water and mixed with the carrier that has been washed and dried with ethanol to obtain the first product;

[0015] Step 2: Add an alkaline solution dropwise to the first product until the pH reaches 6-8, then stop adding the solution and continue stirring to obtain the second product.

[0016] Step 3: After washing, filtering, and drying, the second product is calcined to obtain the final product.

[0017] In one embodiment, in step two, the temperature of the droplet is 50-70°C, the stirring time is 1-3 hours, and the stirring temperature is 50-70°C.

[0018] In one embodiment, the alkaline solution is an ammonium bicarbonate solution and / or an ammonium carbonate solution.

[0019] In one embodiment, in step three, the drying temperature is 85°C, the drying time is 12 hours, the calcination temperature is 350–550°C, and the calcination time is 4–8 hours.

[0020] The present invention also provides the application of the composition comprising any one of the above-described compositions or the product obtained by any one of the above-described preparation methods in a formaldehyde hydration dehydrogenation catalyst.

[0021] In summary, this invention provides a composition comprising an active component, an auxiliary agent, and a support, wherein the active component is a copper salt and the support is aluminum nitride. This invention also provides a method for preparing the above composition, and further provides the application of the above composition or the product obtained by the above preparation method in a formaldehyde hydration dehydrogenation catalyst. The technical solution provided by this invention utilizes an aluminum nitride support, which effectively improves the stability of the catalyst in an aqueous environment; secondly, it allows for the catalytic reforming of most hydrated formaldehyde into H2 and CO2 without the introduction of an additional alkaline medium, while effectively suppressing the formation of the byproduct formic acid; thirdly, it allows for catalytic dehydrogenation under heating conditions, improving reaction efficiency. The composition, preparation method, and application in the field of catalysis provided by this invention solve the technical defects of existing copper-based catalysts used for formaldehyde dehydrogenation, such as easy deactivation, low reaction efficiency, and easy pollution. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 The reaction mechanism in the hydrogen production from formaldehyde hydration decomposition in the technical solution provided by the embodiments of the present invention;

[0024] Figure 2 In the technical solutions provided for embodiments of the present invention, gas phase CG-MS images at 0.5 MPa N2 are obtained when formaldehyde dehydrogenation is performed using CuZnO-AlN, CuZnO catalysis, and without a catalyst (Feed).

[0025] Figure 3 The XRD patterns of the CuZnO-AlN catalyst after calcination and reduction in the optimal technical solution provided in the embodiments of the present invention;

[0026] Figure 4The TEM image of the CuZnO-AlN catalyst after the formaldehyde dehydrogenation catalytic reaction is shown in the optimal technical solution provided in the embodiments of the present invention. Detailed Implementation

[0027] This invention provides a composition, a preparation method, and its application in the field of catalysis, which addresses the technical defects of copper-based catalysts used for formaldehyde dehydrogenation in the prior art, such as easy deactivation, low reaction efficiency, and easy pollution.

[0028] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0031] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0033] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0034] Example 1

[0035] 1.1 Catalyst Preparation

[0036] Aluminum nitride particles with a diameter of 40 nm were washed with ethanol and then calcined and dried in a muffle furnace at 450 °C.

[0037] Weigh 1.6 g of the dried aluminum nitride and dissolve it in 40 ml of a mixed solution of copper nitrate and zinc nitrate (Cu:Zn atomic ratio 2:1). After ultrasonic dispersion for 30 min, titrate with ammonium bicarbonate in a 70 °C water bath until the pH reaches 7-8. Stop titration and maintain the heating temperature. Continue stirring and aging for 2-3 h. Then dry at 85 °C for 8 h. Transfer the sample to a muffle furnace and calcine at 450 °C in air for 6 h to obtain CuO / ZnO-AlN-40nm.

[0038] 1.2 Formaldehyde Aqueous Phase Hydrogen Production

[0039] Prepare a mixed solution of 5 wt% formaldehyde and 95 wt% water for later use. Before using the catalyst, perform H2 reduction in a tubular reduction furnace at 260℃ for 6 hours, and then transfer it to the reactor. Take 15 ml of the mixed solution, add 0.6 g of catalyst, and react at a reaction temperature of 105℃, under a 1 MPa N2 atmosphere and in an alkaline-free medium. Use 4 wt% catalyst and react for 6 hours. After the reaction is complete, cool down. Collect the gaseous products and analyze them by CG-MS gas chromatography. Analyze the liquid products by gas chromatography.

[0040] Analysis showed that the conversion rate of HCHO in the product was 61.49%, the selectivity for methanol was 58.80%, the selectivity for formic acid was 9.21%, and the hydrogen production rate was 26.30 mol·min. -1 ·g -1 .

[0041] Example 2

[0042] 2.1 Catalyst Preparation

[0043] Aluminum nitride particles with a diameter of 1 μm were washed with ethanol and then calcined and dried in a muffle furnace at 450 °C.

[0044] Weigh 1.6g of dried aluminum nitride and dissolve it in 40ml of a mixed solution of copper nitrate and zinc nitrate (Cu:Zn atomic ratio 3:1). After ultrasonic dispersion for 30min, titrate with ammonium bicarbonate in a 70℃ water bath until the pH reaches 7-8. Stop titration, maintain the heating temperature, and continue stirring and aging for 2-3h. Then dry overnight at 85℃. Transfer the sample to a muffle furnace and calcine in air at 450℃ for 6h to obtain CuO / ZnO-AlN-1μm.

[0045] 2.2 Formaldehyde Aqueous Phase Hydrogen Production

[0046] Prepare a mixed solution of 5 wt% formaldehyde and 95 wt% water for later use. Before using the catalyst, perform H2 reduction in a tubular reduction furnace at 260℃ for 6 hours, and then transfer it to the reactor. Take 15 mL of the mixed solution and add 0.6 g of catalyst. React at 105℃, under a 1 MPa N2 atmosphere and in an alkaline-free medium. Use 4 wt% catalyst and react for 6 hours. After the reaction is complete, cool down. Collect the gaseous products and analyze them by CG-MS gas chromatography. Analyze the liquid products by gas chromatography.

[0047] Analysis showed that the conversion rate of HCHO in the product was 91.91%, the selectivity for methanol was 26.67%, the selectivity for formic acid was 5.77%, and the hydrogen production rate was 63.17 mol·min. -1 ·g -1 .

[0048] (Example 2-1, other conditions remained unchanged, but the reaction time was extended to 8 hours, and the results are shown in Table 1)

[0049] Example 3

[0050] 3.1 Catalyst Preparation

[0051] Aluminum nitride particles with a diameter of 1 μm were washed with ethanol and then calcined and dried in a muffle furnace at 450 °C.

[0052] Weigh 1.6g of dried aluminum nitride and dissolve it in 40ml of a mixed solution of copper sulfate and zinc nitrate (Cu:Zn atomic ratio 1:1). After ultrasonic dispersion for 30min, titrate with ammonium bicarbonate in a 70℃ water bath until the pH reaches 7. Stop titration, maintain the heating temperature, and continue stirring and aging for 2-3h. Then dry overnight at 85℃. Transfer the sample to a muffle furnace and calcine in air at 400℃ for 8h to obtain CuO / ZnO-AlN-1μm.

[0053] 3.2 Formaldehyde Aqueous Phase Hydrogen Production

[0054] Prepare a mixed solution of 5 wt% formaldehyde and 95 wt% water for later use. Before using the catalyst, perform H2 reduction in a tubular reduction furnace at 260℃ for 6 hours, and then transfer it to the reactor. Take 15 ml of the mixed solution, add 0.6 g of catalyst, and react at a reaction temperature of 105℃, under a 1 MPa N2 atmosphere and in an alkaline-free medium for 6 hours with 4 wt% catalyst. After the reaction is complete, cool down, collect the gaseous products and analyze them by CG-MS gas chromatography, and analyze the liquid products by gas chromatography.

[0055] Analysis showed that the conversion rate of HCHO in the product was 81.54%, the selectivity for methanol was 36.42%, the selectivity for formic acid was 12.56%, and the hydrogen production rate was 41.52 mol·min. -1 ·g -1 .

[0056] Example 4

[0057] 4.1 Catalyst Preparation

[0058] Aluminum nitride particles with a diameter of 60 μm were washed with ethanol and then calcined and dried in a muffle furnace at 450 °C.

[0059] Weigh 1.6g of dried aluminum nitride and dissolve it in 40ml of a mixed solution of copper nitrate and zinc nitrate (Cu:Zn atomic ratio 3:1). After ultrasonic dispersion for 30min, titrate with ammonium bicarbonate in a 70℃ water bath until the pH reaches 7. Stop titration, maintain the heating temperature, and continue stirring and aging for 2-3h. Then dry overnight at 85℃. Transfer the sample to a muffle furnace and calcine in air at 450℃ for 6h to obtain CuO / ZnO-AlN-60μm.

[0060] 4.2 Formaldehyde-catalyzed reforming reaction in crude trioxymethylene

[0061] A mixed solution of 15 wt% paraformaldehyde, 5 wt% formaldehyde, and 80 wt% water was prepared for use. Before using the catalyst, it was first reduced with H2 at 260℃ for 6 hours in a tubular reduction furnace, and then transferred to the reactor. 15 ml of the mixed solution was taken, and 0.6 g of catalyst was added. The reaction was carried out at a reaction temperature of 105℃, under a 1 MPa N2 atmosphere and in an alkaline-free medium. The catalyst was added at 4 wt% and the reaction was carried out for 6 hours. After the reaction was completed, the mixture was cooled down. The gaseous products were collected and analyzed by CG-MS gas chromatography, and the liquid products were analyzed by gas chromatography.

[0062] Analysis showed that the removal rate of HCHO in the product was 62.60%, the selectivity of methanol was 31.40%, and the selectivity of formic acid was 17.72%.

[0063] Example 5

[0064] 5.1 Catalyst Preparation

[0065] Aluminum nitride particles with a diameter of 60 μm were washed with ethanol and then calcined and dried in a muffle furnace at 450 °C.

[0066] Weigh 1.6g of dried aluminum nitride and dissolve it in 40ml of a mixed solution of copper nitrate and zirconium nitrate (Cu:Zr atomic ratio 3:1). After ultrasonic dispersion for 30min, titrate with ammonium bicarbonate in a 70℃ water bath until the pH reaches 7. Stop titration, maintain the heating temperature, and continue stirring and aging for 2-3h. Then dry overnight at 85℃. Transfer the sample to a muffle furnace and calcine in air at 350℃ for 4h to obtain CuO / ZrO2-AlN-60μm.

[0067] 5.2 Formaldehyde-catalyzed reforming reaction in crude trioxymethylene

[0068] A mixed solution of 15 wt% paraformaldehyde, 5 wt% formaldehyde, and 80 wt% water was prepared for use. Before using the catalyst, it was first reduced with H2 at 260℃ for 6 hours in a tubular reduction furnace, and then transferred to the reactor. 15 ml of the mixed solution was taken, and 0.6 g of catalyst was added. The reaction was carried out at a reaction temperature of 105℃, under a 1 MPa N2 atmosphere and in an alkaline-free medium. The catalyst was added at 4 wt% and the reaction was carried out for 6 hours. After the reaction was completed, the mixture was cooled down. The gaseous products were collected and analyzed by CG-MS gas chromatography, and the liquid products were analyzed by gas chromatography.

[0069] Analysis showed that the HCHO removal rate in the product was 58.21%, the methanol selectivity was 40.27%, the formic acid selectivity was 24.52%, and the hydrogen production rate was 10.32 mol·min. -1 ·g -1 .

[0070] Comparative Example 1

[0071] Catalyst preparation

[0072] Without adding any carrier, 40 ml of copper nitrate and zinc nitrate were prepared into a mixed solution (Cu:Zn atomic ratio 3:1) using a co-precipitation method. After ultrasonic dispersion for 30 min, the solution was titrated with ammonium bicarbonate in a 70℃ water bath until the pH reached 7-8. The solution was then stirred and aged for 2-3 h, and then dried overnight at 85℃. The sample was then transferred to a muffle furnace and calcined in air at 450℃ for 6 h to obtain the CuO / ZnO catalyst.

[0073] For the aqueous hydrogen production from formaldehyde, a mixed solution of 5 wt% formaldehyde and 95 wt% water was prepared and set aside. Before using the catalyst, H2 reduction was carried out in a tubular reduction furnace at 260℃ for 6 hours. After reduction, the solution was transferred to the reactor, and 15 mL of the catalyst was added to 0.6 g of the catalyst. The reaction was carried out at 105℃ under a 1 MPa N2 atmosphere and in an alkaline-free medium. The catalyst was added at 4 wt% and the reaction was carried out for 6 hours. After the reaction was completed, the solution was cooled down. The gaseous products were collected and analyzed by CG-MS gas chromatography, and the liquid products were analyzed by gas chromatography.

[0074] The conversion rate of HCHO in the product was 43.28%, the selectivity for methanol was 35.67%, the selectivity for formic acid was 34.02%, and the hydrogen production rate was 6.58 mol·min. -1 ·g -1 .

[0075] Comparative Example 2

[0076] Catalyst preparation

[0077] Weigh 1.6g of Al2O3 support and dissolve it in 40ml of a mixed solution of copper nitrate and zinc nitrate (Cu:Zn atomic ratio 3:1). After ultrasonic dispersion for 30min, titrate with ammonium bicarbonate in a 70℃ water bath until the pH reaches 7-8. Continue stirring and aging for 2-3h, then dry overnight at 85℃. Transfer the sample to a muffle furnace and calcine in air at 450℃ for 6h to obtain CuO / ZnO-Al2O3.

[0078] Formaldehyde aqueous phase hydrogen production

[0079] Prepare a mixed solution of 5 wt% formaldehyde and 95 wt% water for later use. Before using the catalyst, perform H2 reduction in a tubular reduction furnace at 260℃ for 6 hours. After reduction, transfer the solution to the reactor, take 15 ml of the solution, add 0.6 g of catalyst, and react at 105℃ under a 1 MPa N2 atmosphere in an alkaline-free medium. Use 4 wt% catalyst and react for 6 hours. After the reaction is complete, cool down. Collect the gaseous products and analyze them by CG-MS gas chromatography. Analyze the liquid products by gas chromatography.

[0080] The conversion rate of HCHO in the product was 48.88%, the selectivity for methanol was 40.22%, the selectivity for formic acid was 33.12%, and the hydrogen production rate was 7.07 mol·min. -1 ·g -1 .

[0081] Comparative Example 3

[0082] Catalyst preparation

[0083] Weigh 1.6g of CeO2 support and dissolve it in 40ml of a mixed solution of copper nitrate and zinc nitrate (Cu:Zn atomic ratio 3:1). After ultrasonic dispersion for 30min, titrate with ammonium bicarbonate in a 70℃ water bath until the pH reaches 7-8. Continue stirring and aging for 2-3h, then dry overnight at 85℃. Transfer the sample to a muffle furnace and calcine in air at 450℃ for 6h to obtain CuO / ZnO-CeO2.

[0084] Formaldehyde aqueous phase hydrogen production

[0085] Prepare a mixed solution of 5 wt% formaldehyde and 95 wt% water for later use. Before using the catalyst, perform H2 reduction in a tubular reduction furnace at 260℃ for 6 hours. After reduction, transfer the solution to the reactor, take 15 ml of the solution, add 0.6 g of catalyst, and react at a reaction temperature of 105℃, under a 1 MPa N2 atmosphere and in an alkaline-free medium. The reaction is carried out for 6 hours with 4 wt% catalyst. After the reaction is completed, cool down the reactor. Collect the gaseous products and analyze them by CG-MS gas chromatography. Analyze the liquid products by gas chromatography.

[0086] The conversion rate of HCHO in the product was 55.75%, the selectivity for methanol was 62.14%, the selectivity for formic acid was 24.61%, and the hydrogen production rate was 9.25 mol·min. -1 ·g -1 .

[0087] Comparative Example 4

[0088] Catalyst preparation

[0089] Weigh 1.6g of SiO2 support and dissolve it in 40ml of a mixed solution of copper nitrate and zinc nitrate (Cu:Zn atomic ratio 3:1). After ultrasonic dispersion for 30min, titrate with ammonium bicarbonate in a 70℃ water bath until the pH reaches 7-8. Continue stirring and aging for 2-3h, then dry overnight at 85℃. Transfer the sample to a muffle furnace and calcine in air at 450℃ for 6h to obtain CuO / ZnO-SiO2.

[0090] Formaldehyde catalytic reforming for hydrogen production from crude trioxymethylene

[0091] A mixed solution of 15 wt% trioxymethylene, 5 wt% formaldehyde, and 80 wt% water was prepared for use. Before using the catalyst, H2 reduction was carried out in a tubular reduction furnace at 260℃ for 6 hours. After reduction, the solution was transferred to the reactor, and 15 ml of the catalyst was added. The reaction was carried out at 105℃ under a 1 MPa N2 atmosphere in an alkaline-free medium with 4 wt% catalyst for 6 hours. After the reaction was completed, the solution was cooled down. The gaseous product was collected and analyzed by CG-MS gas chromatography, and the liquid product was analyzed by gas chromatography. The removal rate of HCHO in the product was 27.26%, the selectivity of methanol was 40.17%, the selectivity of formic acid was 32.75%, and the hydrogen production rate was 4.21 mol·min. -1 ·g -1 .

[0092] Comparative Example 5

[0093] Catalyst preparation

[0094] Weigh 1.6 g of MnO2 support and dissolve it in 40 ml of a mixed solution of copper nitrate and zinc nitrate (Cu:Ce atomic ratio 1:1). After ultrasonic dispersion for 30 min, titrate with ammonium bicarbonate in a 70 °C water bath until the pH reaches 7-8. Continue stirring and aging for 2-3 h, then dry overnight at 85 °C. Transfer the sample to a muffle furnace and calcine in air at 350 °C for 8 h to obtain CuO / CeO-MO2.

[0095] Formaldehyde catalytic reforming for hydrogen production from crude trioxymethylene

[0096] A mixed solution of 15 wt% trioxymethylene, 5 wt% formaldehyde, and 80 wt% water was prepared for use. Before using the catalyst, H2 reduction was carried out in a tubular reduction furnace at 260℃ for 6 hours. After reduction, the solution was transferred to the reactor, and 15 ml of the catalyst was added. The reaction was carried out at 105℃ under a 1 MPa N2 atmosphere in an alkaline-free medium with 4 wt% catalyst for 6 hours. After the reaction was completed, the solution was cooled down. The gaseous product was collected and analyzed by CG-MS gas chromatography, and the liquid product was analyzed by gas chromatography. The removal rate of HCHO in the product was 34.21%, the selectivity of methanol was 46.52%, the selectivity of formic acid was 36.70%, and the hydrogen production rate was 6.74 mol·min. -1 ·g -1 .

[0097] For the relevant results data on the catalytic dehydrogenation effect of formaldehyde in each embodiment and comparative example, please refer to Table 1.

[0098] Table 1

[0099]

[0100] As shown in Table 1, under the same reaction conditions, the CuO / ZnO catalyst supported on ALN ​​exhibits a significantly higher formaldehyde conversion rate and a significantly lower formic acid selectivity compared to other supported catalysts. Among them, Example 2 shows the best catalytic effect, with a hydrogen production rate of 63.17 mol·min⁻¹. -1 ·g -1 .

[0101] Depend on Figure 2 As shown, under the same conditions, CuO / ZnO-AlN detected more H2 and CO2 compared to CuZnO and without catalyst (Feed), proving that the support has good catalytic ability to hydrate formaldehyde into H2 and CO2.

[0102] Depend on Figure 3 As shown, Figure 3 The XRD patterns of CuZnO-AlN after preparation and reduction are shown by... Figure 3 As can be seen, after calcination at 450℃, the CuO and ZnO crystal phases of CuO / ZnO-AlN remain intact. After reduction with H2, CuO in the CuO / ZnO-AlN catalyst can be fully reduced to Cu elemental, and the AlN support can effectively anchor Cu elemental, making it less prone to oxidation in air.

[0103] The technical solution provided by this invention will now be further explained in conjunction with the mechanism.

[0104] In the technical solution provided by the embodiments of the present invention, the catalyst is obtained by depositing the Cu active component onto the AlN support through a precipitant, followed by drying, grinding, and calcination.

[0105] During the reaction, the high thermal conductivity of AlN material and the hydrolysis of the AlN support to form an Al(OH)3 layer coating the catalyst surface anchor copper, effectively inhibiting the migration, leaching, and oxidation of Cu particles during the reaction. This significantly improves the stability and catalytic activity of the catalyst in an aqueous environment (TEM image after reaction is shown). Figure 4 (As shown).

[0106] Second, during the reaction, the AlN support will slowly hydrolyze under neutral or weakly acidic conditions, resulting in the following reactions: AlN + H2O → Al(OH)3 + NH3, NH3 + H2O → NH4 + +OH - That is, while forming an Al(OH)3 layer coating the catalyst surface, a trace amount of OH is generated in situ. - Without changing the solution pH, hydrated formaldehyde effectively adsorbed near the catalyst forms a Cannizaro reaction intermediate, and in Cu 0 Catalysis promotes the hydration reaction of formaldehyde.

[0107] Under the same reaction conditions, the particle size of AlN has a significant impact on its hydrolysis rate; the smaller the particle size, the faster the hydrolysis rate. An excessively fast hydrolysis rate not only easily damages the AlN support structure and results in an excessively thick Al(OH)3 layer, which hinders contact between reactants and catalyst, leading to a decrease in catalytic efficiency and lifetime; conversely, an excessively slow hydrolysis rate leads to the formation of the Al(OH)3 layer and OH groups. - The amount of AlN is too small to fully utilize its hydrolytic effect on the catalyst. Therefore, the particle size of AlN is crucial for regulating the hydrolysis of the catalyst. This patent uses AlN particles with a particle size of 1–10 μm as the optimal support.

[0108] Compared to other supported Cu-based catalysts, this catalyst, through its Al(OH)3 layer coating, exhibits improved high-temperature stability in aqueous media; the generated trace amounts of OH... - It promotes the catalytic process of formaldehyde hydration.

[0109] Under conditions without the addition of alkaline media, it can significantly improve the formaldehyde removal rate while catalyzing the decomposition of hydrated formaldehyde into H2 and CO2, effectively inhibiting the formaldehyde disproportionation reaction and suppressing the generation of byproducts methanol and formic acid.

[0110] Third, aluminum nitride has good acid resistance and can effectively suppress corrosion caused by formic acid formation when used as a carrier.

[0111] Fourth, in the technical solution provided by the embodiments of the present invention, copper salt is selected as the active ingredient. In terms of preparation cost, it has a lower preparation cost compared with the active ingredients of precious metals. Moreover, the reducing power of copper salt has high selectivity. It does not have the reducing power for carbon-carbon double bonds, but only for carbon-oxygen double bonds, which further avoids the occurrence of disproportionation reaction.

[0112] Based on this, the technical solutions provided by the embodiments of the present invention can be widely applied in the following fields.

[0113] First, formaldehyde reforming for hydrogen production under relatively high reaction temperatures in an alkaline environment. In existing technologies, most formaldehyde hydration dehydrogenation reactions require high temperature and high alkalinity conditions. Although high temperatures are beneficial for catalytic reforming, they also promote the disproportionation of formaldehyde to produce methanol and formic acid; therefore, the reaction temperature should not be too high.

[0114] In this invention, due to trace amounts of OH -In-situ generation allows for formaldehyde dehydrogenation without the need for an additional alkaline medium. Simultaneously, the formation of an Al(OH)3 layer creates a confinement effect, resulting in high stability in the aqueous reaction system. Combined with AlN's excellent thermal conductivity and acid corrosion resistance, catalysis can be performed at higher reaction temperatures (105℃) (compared to most other reaction temperatures below 70℃). This improves formaldehyde conversion while suppressing the Cannizaro side reaction.

[0115] Secondly, it is applicable to applications such as the purification of formaldehyde using trioxymethylene as a byproduct. In existing technologies, while high temperatures help improve formaldehyde conversion rates, they also lead to decreased catalyst stability and increased rates of the Cannizaro disproportionation side reaction in actual reactions. Therefore, current research focuses primarily on low-temperature catalysis, but the formaldehyde conversion rate is often low, resulting in potentially poor formaldehyde removal efficiency. The technical solution provided by this invention allows the catalyst to remove formaldehyde at higher temperatures without introducing acidic or alkaline media, while simultaneously significantly promoting the formation of formic acid, thus enabling its use in the removal of formaldehyde as a byproduct.

[0116] Taking the application of trioxymethylene (TOM) in formaldehyde removal and refining as an example, it is well known that TOM is synthesized from concentrated formaldehyde through reactive distillation. The gaseous distillate from reactive distillation mainly contains TOM, water, formaldehyde (5 wt%), and other impurities. In actual refining processes, formaldehyde forms an azeotrope of TOM-water-formaldehyde and is easily converted into byproducts such as formic acid, methanol, and methyl formate. In particular, the formic acid generated by the oxidation / disproportionation of formaldehyde can corrode production equipment and pipelines, and shutdowns and maintenance operations severely affect the company's production capacity, greatly increasing the difficulty and cost of subsequent refining. This catalyst can also effectively remove formaldehyde.

[0117] The technical solution provided by this invention has the following advantages:

[0118] (1) High formaldehyde removal rate: with 4wt% catalyst, the formaldehyde removal rate can reach up to 100% after 6-8 hours of reaction.

[0119] (2) The catalyst can significantly inhibit the formaldehyde disproportionation reaction to produce methanol, and the catalyst has good formic acid decomposition ability; gas chromatography detection of tail gas showed that only H2 and CO2 were detected, and CO was not detected.

[0120] (3) The catalyst has good water resistance, and no Cu component leachates out after the reaction.

[0121] (4) The process of this invention is simple, low-cost, pollution-free, safe and environmentally friendly, and can be produced and used on a large scale. It shows great potential in the application of formaldehyde removal in formaldehyde wastewater.

[0122] The technical solution provided by this invention solves the following technical problems.

[0123] (1) This paper presents a new application of AlN material as a catalyst support for the catalysis of formaldehyde, namely: using it as a Cu catalyst support, utilizing the core-shell structure formed during the reaction of AlN with water to form Al(OH)3, which inhibits the reduction of Cu in the catalyst after H2 reduction. 0 Oxidation and leaching in water improve the stability of the catalyst in aqueous environments and achieve metal confinement.

[0124] At the same time, the trace amounts of OH generated - It can form a cannizaro intermediate in an alkaline environment, effectively inhibiting the aggregation of Cu particles, thus exhibiting a high formaldehyde removal capacity. It can also significantly inhibit the cannizaro disproportionation reaction, converting most of the formaldehyde into H2 and CO2.

[0125] (2) Compared with other Cu-based catalysts, this catalyst can significantly suppress the formaldehyde disproportionation side reaction at a higher reaction temperature. This can ensure the effective removal of formaldehyde and effectively suppress the formic acid generated by the formaldehyde disproportionation reaction, thereby avoiding the equipment and pipeline corrosion problems caused by the formation of formic acid. This eliminates the negative effects of formaldehyde and formic acid in the refining process of crude trioxymethylene, which has never happened before in the refining of crude trioxymethylene.

[0126] In summary, this invention provides a composition comprising an active component, an auxiliary agent, and a support, wherein the active component is a copper salt and the support is aluminum nitride. This invention also provides a method for preparing the above composition, and further provides the application of the above composition or the product obtained by the above preparation method in a formaldehyde hydration dehydrogenation catalyst. The technical solution provided by this invention utilizes an aluminum nitride support, which effectively improves the stability of the catalyst in an aqueous environment; secondly, it allows for the catalytic reforming of most hydrated formaldehyde into H2 and CO2 without the introduction of an additional alkaline medium, while effectively suppressing the formation of the byproduct formic acid; thirdly, it allows for catalytic dehydrogenation under heating conditions, improving reaction efficiency. The composition, preparation method, and application in the field of catalysis provided by this invention solve the technical defects of existing copper-based catalysts used for formaldehyde dehydrogenation, such as easy deactivation, low reaction efficiency, and easy pollution.

[0127] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. Furthermore, other implementation methods can be derived from the above embodiments, allowing for structural and logical substitutions and changes without departing from the scope of this disclosure.

[0128] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a composition, characterized in that, The raw materials of the composition, by mass, include: 10-30 parts of active component, 5-10 parts of auxiliary agent and 20-40 parts of carrier, wherein the active component is a copper salt, the carrier is aluminum nitride and the particle size of the carrier is 1μm-10μm, and the auxiliary agent is selected from any one or more of salt solutions containing Zn, Zr, Ce and Ni. The preparation method is as follows: Step 1: The active component and additives are dissolved in water and mixed with the carrier that has been washed and dried with ethanol to obtain the first product; Step 2: Add an alkaline solution dropwise to the first product until the pH reaches 6-8, then stop adding the solution and continue stirring to obtain the second product. The temperature of the dropwise addition is 50-70°C, and the stirring time is 1-3 hours. The stirring temperature is 50-70°C. Step 3: After washing, filtering, and drying, the second product is calcined to obtain the final product.

2. The preparation method according to claim 1, characterized in that, The copper salt is selected from any one or more of copper nitrate, copper acetate, and copper sulfate.

3. The preparation method according to claim 1, characterized in that, The alkaline solution is an ammonium bicarbonate solution and / or an ammonium carbonate solution.

4. The preparation method according to claim 1, characterized in that, In step three, the drying temperature is 65~120℃, the drying time is 8~12 h, the calcination temperature is 350~550℃, and the calcination time is 4~8 h.

5. The application of a product obtained by the preparation method according to any one of claims 1 to 4 in a formaldehyde hydration dehydrogenation catalyst.

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