阅读说明：本技术 一种宏量制备多种甲醛分解催化剂的方法 (Method for macro-preparation of multiple formaldehyde decomposition catalysts ) 是由 纪红兵 张�浩 何晓辉 张颖 于 2021-08-13 设计创作，主要内容包括：本发明提供一种宏量制备多种甲醛分解催化剂的方法,该甲醛分解催化剂的制备包括以下步骤：首先将金属前驱体倒入溶剂中并超声溶解,再加入配合物并搅拌均匀,得到澄清的配合物溶液；将准备好的催化剂载体材料铺平,通过雾化器将配合物溶液均匀沉积于催化剂载体材料表面；最后烘干并煅烧,得到常温下分解甲醛的催化剂；本发明原料易得、成本低、制备方法简单且可以大规模合成。所制备的多种催化剂室温下甲醛去除率高达99％,可实现室温下完全转化空速为20000mL·g～(-1)·h～(-1)的甲醛气体,且具备优异的稳定性。(The invention provides a method for massively preparing various formaldehyde decomposition catalysts, which comprises the following steps: firstly, pouring a metal precursor into a solvent, ultrasonically dissolving the metal precursor, adding a complex, and uniformly stirring to obtain a clear complex solution; paving the prepared catalyst carrier material, and uniformly depositing the complex solution on the surface of the catalyst carrier material through an atomizer; finally, drying and calcining to obtain a catalyst for decomposing formaldehyde at normal temperature; the invention has the advantages of easily obtained raw materials, low cost, simple preparation method and large-scale synthesis. The formaldehyde removal rate of the prepared multiple catalysts at room temperature is up to 99 percent, and the complete conversion space velocity at room temperature can be realized to be 20000 mL-g ‑1 ·h ‑1 The formaldehyde gas of (2) and has excellent stability.)

1. A method for preparing a plurality of formaldehyde decomposition catalysts in a macroscopic quantity is characterized by comprising the following steps:

first step preparation of Complex solution

Pouring the metal precursor into a solvent, and fully dissolving by ultrasonic; adding the complex, and fully and uniformly stirring to form a clear and transparent complex solution;

second step of loading metal elements

Uniformly paving a catalyst carrier material, injecting the complex solution prepared in the step one) into an atomizer, starting the atomizer to enable the solution to be uniformly deposited on the surface of the catalyst carrier material, turning over the catalyst carrier material every about 0.5-1.5 hours and paving the catalyst carrier material uniformly again until the solution is completely consumed, collecting a catalyst precursor and putting the catalyst precursor in a vacuum drying oven for overnight;

third step of calcination

And (3) putting the porcelain boat filled with the catalyst precursor into a tubular furnace for calcining, and cooling to room temperature to obtain the catalyst.

2. The method of claim 1, wherein the metal precursor is CoCl₂，CoBr₂，CoI₂，Co(NO₃)₂，MnCl₂，Mn(NO₃)₂，Ce(NO₃)₃，CeCl₃，NiCl₂，Ni(NO₃)₂，PtCl₄，Pt(NO₃)₂，H₁₂N₆O₆Pt，PdCl₂，Pd(NO₃)₂And AgNO₃Of the above-mentioned group.

3. The method for macro-preparation of formaldehyde decomposition catalysts according to claim 1, wherein the complex is one or more selected from ethylenediamine, 1, 10-diazophenanthrene, ethylenediamine tetraacetic acid, 2' -bipyridine, dimethylimidazole, 1, 10-phenanthroline, monoethanolamine, diethanolamine, triethanolamine, sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate, sodium aminotriacetate, ethylenediamine tetraacetate (disodium or tetrasodium EDTA) and diethylenetriamine pentacarboxylate (DTPA).

4. The general method for macro-preparation of formaldehyde decomposition catalysts according to claim 1, wherein the solvent is one or more of methanol, deionized water, acetonitrile, acetone, toluene, ammonia, ethanol, acetic acid, and dilute hydrochloric acid.

5. The method of claim 1, wherein the catalyst support material is one or more selected from the group consisting of molecular sieves, alumina, iron oxyhydroxide, iron oxide, manganese oxide, cerium oxide, titanium oxide, zinc oxide, acetylene black, graphene, phthalocyanines, carbon nanotubes, porphyrins, carbon fibers, carbon spheres, activated carbon, and diamond.

6. The method for macro preparation of formaldehyde decomposition catalyst according to claim 1, wherein the calcination is one or more selected from the group consisting of calcination under air, calcination under inert gas protection, calcination under ammonia atmosphere, calcination under hydrogen atmosphere, and calcination under carbon monoxide atmosphere.

7. The general method for macro preparation of multiple formaldehyde decomposition catalysts as claimed in claim 1, wherein the calcination temperature is 100 ℃ and 1200 ℃, the holding time is 0.1-20h, and the heating rate is 1-50 ℃/min.

8. The general method for macro preparation of multiple formaldehyde decomposition catalysts according to claim 1, wherein the concentration of the complex solution is 1-15 mmol/L.

Technical Field

The invention relates to the technical field of material science and engineering, in particular to a universal method for massively preparing various formaldehyde decomposition catalysts.

Background

Among indoor air pollutants, formaldehyde is one of the focuses that cannot be ignored. The formaldehyde is easily released from building and furniture materials in home decoration, and the release period can be as long as fifteen years. Therefore, the method has important significance in purifying formaldehyde in the air.

The prior methods for removing formaldehyde comprise: plasma method, physical adsorption method, photocatalytic oxidation method and catalytic oxidation method. Compared with other methods, the catalytic oxidation method can decompose formaldehyde into CO₂And H₂O, the degradation of formaldehyde is most complete and no harmful by-products are produced. At present, most catalysts adopt precious metals such as platinum and the like as active centers for catalyzing and decomposing formaldehyde, but the rarity and high cost of the precious metals greatly limit the large-scale application of the precious metals. It has therefore been very challenging to develop non-noble metal catalysts that can completely catalytically decompose formaldehyde at room temperature, while having high activity and excellent stability.

The invention patent CN 101380574A of China utilizes three parts of a porous inorganic oxide carrier, a noble metal component and an auxiliary agent to synthesize a noble metal catalyst for catalyzing and completely oxidizing formaldehyde at room temperature. The catalyst has the characteristics of excellent catalytic performance and the like, but the supported elements are noble metals, so the cost is high and the catalyst is difficult to popularize and use.

Chinese patent CN 105148917a adopts sodium borohydride solution to reduce nano-sheet shaped triple-diamond tetroxide to increase its surface oxygen defect, and can effectively catalyze and degrade formaldehyde into nontoxic carbon dioxide and water at 70 ℃.

Disclosure of Invention

Based on the defects of high cost, small synthesis magnitude, complex synthesis steps, heating catalysis and the like of various current catalysts for catalytically decomposing formaldehyde, the invention aims to provide a method for massively preparing various formaldehyde decomposition catalysts so as to solve the problems of high cost, small synthesis magnitude, complex preparation process, incapability of achieving catalytic effect under room temperature and the like of the formaldehyde decomposition catalysts.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing a plurality of formaldehyde decomposition catalysts in a macroscopic quantity comprises the following steps:

the first step is as follows: preparing a complex solution:

pouring the metal precursor into a solvent, and fully dissolving by ultrasonic; then adding the complex, and fully and uniformly stirring to form a clear and transparent complex solution.

The second step is that: carrying metal elements:

uniformly paving the catalyst carrier material, injecting the prepared metal complex solution into an atomizer, starting the atomizer to uniformly deposit the solution on the surface of the catalyst carrier material, turning over the catalyst carrier material every about one hour, and uniformly paving the catalyst carrier material again. The catalyst precursor was collected and placed in a vacuum oven overnight until the solution was depleted.

The third step: and (3) calcining:

and (3) putting the porcelain boat filled with the catalyst precursor into a tubular furnace for calcining, and cooling to room temperature to obtain the catalyst.

Preferably, in the method for preparing a plurality of formaldehyde decomposition catalysts in a macroscopic quantity, the metal precursor is CoCl₂， CoBr₂，CoI₂，Co(NO₃)₂，MnCl₂，Mn(NO₃)₂，Ce(NO₃)₃，CeCl₃，NiCl₂，Ni(NO₃)₂，PtCl₄， Pt(NO ) ，H₁₂N₆O₆Pt，PdCl₂，Pd(NO₃)₂And AgNO₃One or a combination of several of them.

Preferably, in the method for macro-preparation of a plurality of formaldehyde decomposition catalysts, the complex is one or a combination of several of ethylenediamine, 1, 10-diazophenanthrene, ethylenediamine tetraacetic acid, 2' -bipyridine, dimethylimidazole, 1, 10-phenanthroline, monoethanolamine, diethanolamine, triethanolamine, sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate, sodium aminotriacetate, ethylenediamine tetraacetate (disodium EDTA or tetrasodium) and diethylenetriamine pentacarboxylate (DTPA).

Preferably, in the method for preparing a plurality of formaldehyde decomposition catalysts in a macroscopic quantity, the catalyst carrier material is one or a combination of several of molecular sieve, aluminum oxide, iron oxyhydroxide, iron oxide, manganese oxide, cerium oxide, titanium oxide, zinc oxide, acetylene black, graphene, phthalocyanine, carbon nanotube, porphyrin, carbon fiber, carbon sphere, activated carbon and diamond.

Preferably, in the method for preparing a plurality of formaldehyde decomposition catalysts in a macroscopic quantity, the calcination mode is one or a mixture of more of calcination in air, calcination under the protection of inert gas, calcination in an ammonia atmosphere, calcination in a hydrogen atmosphere and calcination in a carbon monoxide atmosphere.

Preferably, in the method for massively preparing the formaldehyde decomposition catalysts, the calcining temperature is 100-1200 ℃, the heat preservation time is 0.1-20h, and the heating rate is 1-50 ℃/min.

Compared with the prior art, the invention has the following beneficial effects:

1. the technical scheme provided by the invention adopts an atomizer to uniformly deposit the metal precursor complex solution on the surface of a catalyst carrier material, and the catalyst with highly dispersed metal active centers can be obtained by simple burning, so that the complete catalytic decomposition of formaldehyde at room temperature is realized. Wherein, the carrier material and the metal precursor can be purchased commercially, thereby avoiding the problem of complex synthesis of most catalyst carriers and specific metal precursors.

2. The technical scheme provided by the invention has the advantages of low preparation cost and simple operation, does not need complex and expensive synthesis equipment, and can be synthesized on a large scale.

3. The catalyst prepared by the technical scheme provided by the invention has the advantages that the metal active center is uniformly dispersed, the catalytic activity is high, and the formaldehyde can be completely decomposed into CO at room temperature₂And H₂O, the formaldehyde removal rate at room temperature is up to 99 percent, and the complete conversion space velocity at room temperature can be realized to be 20000 mL-g^-1·h^-1The formaldehyde gas of (2) has excellent stability.

Drawings

FIG. 1 shows the results of the formaldehyde assay in example 1;

FIG. 2 shows the results of stability tests of the formaldehyde experiment in example 1;

FIG. 3 shows the pathway of catalytic decomposition of formaldehyde by the synthesized cobalt catalyst and the products formed in example 1 under room temperature conditions with mass spectrometry.

FIG. 4 is a diagram of a transmission electron microscope AC-HAADF-STEM for spherical aberration correction of a formaldehyde decomposition catalyst in which Co element is highly dispersed in example 1;

FIG. 5 shows the results of the formaldehyde assay in example 2;

FIG. 6 shows the results of stability tests of the formaldehyde experiment in example 2;

FIG. 7 is a high resolution TEM characterization of the synthesized molecular sieve supported cobalt nanoparticle catalyst of example 2;

FIG. 8 is a standard curve as described in all examples;

Detailed Description

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the scope shown in the examples.

Example 1

Weighing cobalt nitrate hexahydrate, pouring the weighed cobalt nitrate hexahydrate into 40L of deionized water, and carrying out ultrasonic full dissolution to prepare a clear and transparent solution with the cobalt concentration of 2 mmol/L. Spreading 500g of acetylene black doped with nitrogen, injecting the cobalt complex solution into an atomizer, and starting the atomizer to uniformly deposit the solution on the surface of a catalyst carrier material. Turning over the catalyst carrier material every about one hour and uniformly spreading again to ensure that the cobalt element on the surface of the catalyst is uniformly dispersed. Until 40L of the solution was consumed, the catalyst precursor was collected and placed in a vacuum oven overnight at 60 ℃. Finally, the sample is placed in N₂Calcining for 2h at the temperature of 600 ℃ in the atmosphere to obtain the cobalt catalyst for catalyzing and decomposing formaldehyde at room temperature.

Catalytic HCHO oxidation activity was evaluated in a fixed bed reactor with 300mg of catalyst. By using N at a flow rate of 20mL/min₂The mixture was passed through a 4 wt% aqueous formaldehyde solution and then mixed with 25% O at a flow rate of 80mL/min₂Mixing (N)₂As an equilibrium gas) to a concentration of50ppm of HCHO gas. The conversion of formaldehyde was determined by measuring the concentration of HCHO in the inlet and outlet gas streams. The formaldehyde concentration was determined by phenol spectrophotometry as follows: first, a cumulative volume of 100mL of a gas stream containing HCHO was bubbled through a gas containing C₆H₄SN(CH₃)C＝NNH₂·HCl(1×10-⁴wt%, 5 mL); then, NH is added₄Fe(SO₄)₂·12H₂O (1 wt%, 0.4mL, dissolved in 0.1M HCl) and the mixture was left to stand in the dark for 15 minutes. The HCHO concentration is obtained by reading the absorbance at 630nm by using a spectrophotometer and comparing the data with a standard curve, the detection result refers to figure 1, the fact that the inlet obviously contains formaldehyde and the outlet formaldehyde concentration is close to that of a blank solution can be found, which shows that the removal rate of the formaldehyde of the prepared catalyst at room temperature is up to 99 percent, and the complete conversion space velocity at room temperature is 20000 mL-g^-1·h^-1The formaldehyde gas of (2). Referring to fig. 2, it can be seen that the formaldehyde removal rate is still over 90% after 150h, indicating that the stability is excellent. Furthermore, by switching O₂And N₂Monitoring the change of tail gas in real time and finding the introduction of O₂CO in time-dependent tail gas₂Increased concentration, no O₂CO in tail gas when in introduction₂The concentration decreased, indicating that the catalyst was produced by decomposition of formaldehyde to CO₂To achieve the degradation of formaldehyde, see figure 3. The formaldehyde decomposition catalyst with highly dispersed Co element can be seen through a spherical aberration correction transmission electron microscope AC-HAADF-STEM picture; the white bright spot is monatomic cobalt metal, see fig. 4.

Example 2

Weighing cobalt nitrate hexahydrate, pouring the cobalt nitrate hexahydrate into 30L of deionized water, and carrying out ultrasonic full dissolution to prepare a solution with the cobalt concentration of 2.5 mmol/L. Then 0.3kg of ethylenediamine chelating agent is added into the solution, and the mixture is fully and uniformly stirred to form clear and transparent complex solution. And paving 200g of ZSM-5 molecular sieve, injecting the cobalt complex solution into an atomizer, and starting the atomizer to uniformly deposit the solution on the surface of the catalyst carrier material. Turning over the catalyst carrier material every about one hour and uniformly spreading again to ensure that the cobalt element on the surface of the catalyst is uniformly dispersed. Until 30L of the solution was depleted, the catalyst precursor was collected and placed in a vacuum oven overnight at 60 ℃. Finally, the sample was calcined in an air atmosphere at a temperature of 200 ℃ for 2 h. So as to obtain the cobalt catalyst for catalyzing and decomposing formaldehyde at room temperature.

Catalytic HCHO oxidation activity was evaluated in a fixed bed reactor with 300mg of catalyst. By using N at a flow rate of 20mL/min₂The stream was passed through a 3 wt% strength aqueous formaldehyde solution to produce HCHO gas at a concentration of 40 ppm. Then mixed with 25% O at a flow rate of 80mL/min₂Mixing (N)₂As an equilibrium gas) to produce HCHO vapor. The conversion of formaldehyde was determined by measuring the concentration of HCHO in the inlet and outlet gas streams. The formaldehyde concentration was determined by phenol spectrophotometry as follows: first, a cumulative volume of 100mL of a gas stream containing HCHO was bubbled through a gas containing C₆H₄SN(CH₃)C＝NNH₂·HCl(1×10- ⁴wt%, 5 mL); then, NH is added₄Fe(SO₄)₂·12H₂O (1 wt%, 0.4mL, dissolved in 0.1M HCl) and the mixture was left to stand in the dark for 15 minutes. The HCHO concentration is obtained by reading the absorbance at 630nm by using a spectrophotometer and comparing the data with a standard curve, the detection result refers to figure 5, the fact that the inlet obviously contains formaldehyde and the outlet formaldehyde concentration is close to that of a blank solution can be found, which shows that the removal rate of the formaldehyde of the prepared catalyst at room temperature is up to 99 percent, and the complete conversion space velocity at room temperature is 20000 mL-g^-1·h^-1The formaldehyde gas of (2). As shown in fig. 6, after 100h, the formaldehyde removal rate is still over 90%, indicating that the stability is excellent. The high resolution transmission electron microscope characterization map is shown in FIG. 7.

Example 3

Weighing cobalt nitrate hexahydrate, pouring the cobalt nitrate hexahydrate into 10L of methanol solvent, and carrying out ultrasonic full dissolution to prepare a solution with the cobalt concentration of 5 mmol/L. Then 0.25kg of dimethyl imidazole is added into the solution, and the mixture is fully and evenly stirred to form clear and transparent complex solution. And paving 100g of activated carbon, injecting the cobalt complex solution into an atomizer, and starting the atomizer to uniformly deposit the solution on the surface of the catalyst carrier material. Turning over the catalyst carrier material every about one hour and uniformly spreading again to ensure that the cobalt element on the surface of the catalyst is uniformly dispersed. Until 10L of the solution is dissolvedThe solution was depleted and the catalyst precursor was collected and placed in a vacuum oven overnight at 60 ℃. Finally, the sample is placed in N₂Calcining at 600 ℃ for 2h in the atmosphere. So as to obtain the cobalt catalyst for catalyzing and decomposing formaldehyde at room temperature.

Catalytic HCHO oxidation activity was evaluated in a fixed bed reactor with 300mg of catalyst by using N at a flow rate of 20mL/min₂The mixture was passed through a 4 wt% aqueous formaldehyde solution and then mixed with 25% O at a flow rate of 80mL/min₂Mixing (N)₂As an equilibrium gas) to produce HCHO gas at a concentration of 50 ppm. The conversion of formaldehyde was determined by measuring the concentration of HCHO in the inlet and outlet gas streams. The formaldehyde concentration was determined by phenol spectrophotometry as follows: first, a cumulative volume of 100mL of a gas stream containing HCHO was bubbled through a gas containing C₆H₄SN(CH₃)C＝NNH₂·HCl(1×10-⁴wt%, 5 mL); then, NH is added₄Fe(SO₄)₂·12H₂O (1 wt%, 0.4mL, dissolved in 0.1M HCl) and the mixture was left to stand in the dark for 15 minutes. HCHO concentrations were obtained by reading the absorbance at 630nm using a spectrophotometer and comparing the data to a standard curve.

Example 4

Weighing platinum chloride, pouring the platinum chloride into 40L of deionized water, and carrying out ultrasonic full dissolution to prepare a solution with the platinum concentration of 10 mmol/L. Then 0.6kg of ethylenediamine chelating agent is added into the solution, and the mixture is fully and uniformly stirred to form clear and transparent complex solution. And (3) paving 200g of silicon oxide, injecting the platinum complex solution into an atomizer, and starting the atomizer to uniformly deposit the solution on the surface of the catalyst carrier material. Turning over the catalyst carrier material every about one hour and uniformly spreading again to ensure that the platinum element on the surface of the catalyst is uniformly dispersed. Until 40L of the solution was consumed, the catalyst precursor was collected and placed in a vacuum oven overnight at 60 ℃. Finally, the sample was calcined in an air atmosphere at a temperature of 400 ℃ for 2 h. So as to obtain the platinum catalyst for catalyzing and decomposing formaldehyde at room temperature.

Catalytic HCHO oxidation activity was evaluated in a fixed bed reactor with 300mg of catalyst. By using N at a flow rate of 20mL/min₂The stream was passed through a 4% strength by weight aqueous formaldehyde solution and then mixed with 8025% O of mL/min flow rate₂Mixing (N)₂As an equilibrium gas) to produce HCHO gas at a concentration of 50 ppm. The conversion of formaldehyde was determined by measuring the concentration of HCHO in the inlet and outlet gas streams. The formaldehyde concentration was determined by phenol spectrophotometry as follows: first, a cumulative volume of 100mL of a gas stream containing HCHO was bubbled through a gas containing C₆H₄SN(CH₃)C＝NNH₂·HCl(1×10-⁴wt%, 5 mL); then, NH is added₄Fe(SO₄)₂·12H₂O (1 wt%, 0.4mL, dissolved in 0.1M HCl) and the mixture was left to stand in the dark for 15 minutes. HCHO concentrations were obtained by reading the absorbance at 630nm using a spectrophotometer and comparing the data to a standard curve.

Example 5

Weighing nickel acetate, pouring into 3L of deionized water, and carrying out ultrasonic full dissolution to prepare a solution with the nickel concentration of 2 mmol/L. Then 0.2kg of 1, 10-phenanthroline is added into the solution, and the mixture is fully and uniformly stirred to form a clear and transparent complex solution. 50g of acetylene black is taken out and laid flat, the nickel complex solution is injected into an atomizer, and the atomizer is started to ensure that the solution is uniformly deposited on the surface of the catalyst carrier material. Turning over the catalyst carrier material every about one hour and uniformly spreading again to ensure that the cobalt element on the surface of the catalyst is uniformly dispersed. Until 3L of the solution was consumed, the catalyst precursor was collected and placed in a vacuum oven overnight at 60 ℃. Finally, the sample is placed in N₂Calcining at 600 ℃ for 2h in the atmosphere. So as to obtain the nickel catalyst for catalyzing and decomposing formaldehyde at room temperature.

Catalytic HCHO oxidation activity was evaluated in a fixed bed reactor with 300mg of catalyst. By using N at a flow rate of 20mL/min₂The mixture was passed through a 3 wt% aqueous formaldehyde solution and then mixed with 25% O at a flow rate of 80mL/min₂Mixing (N)₂As an equilibrium gas) to produce HCHO gas at a concentration of 40 ppm. The conversion of formaldehyde was determined by measuring the concentration of HCHO in the inlet and outlet gas streams. The formaldehyde concentration was determined by phenol spectrophotometry as follows: first, a cumulative volume of 100mL of a gas stream containing HCHO was bubbled through a gas containing C₆H₄SN(CH₃)C＝NNH₂·HCl(1×10-⁴wt%, 5 mL); then, NH is added₄Fe(SO₄)₂·12H₂O (1 wt%, 0.4mL, dissolved in 0.1M HCl) and the mixture was left to stand in the dark for 15 minutes. HCHO concentrations were obtained by reading the absorbance at 630nm using a spectrophotometer and comparing the data to a standard curve.

Example 6

Weighing manganese nitrate, pouring the manganese nitrate into 4L of deionized water, and carrying out ultrasonic full dissolution to prepare a clear and transparent solution with the cobalt concentration of 5 mmol/L. 100g of acetylene black doped with nitrogen elements is paved, a manganese complex solution is injected into an atomizer, and the atomizer is started to ensure that the solution is uniformly deposited on the surface of a catalyst carrier material. Turning over the catalyst carrier material every about one hour and uniformly spreading again to ensure that the manganese element on the surface of the catalyst is uniformly dispersed. Until 4L of the solution was consumed, the catalyst precursor was collected and placed in a vacuum oven overnight at 60 ℃. Finally, the sample is placed in NH₃Calcining at 600 ℃ for 2h in the atmosphere. So as to obtain the manganese catalyst for catalyzing and decomposing formaldehyde at room temperature.

Catalytic HCHO oxidation activity was evaluated in a fixed bed reactor with 300mg of catalyst. By using N at a flow rate of 20mL/min₂The mixture was passed through a 3 wt% aqueous formaldehyde solution and then mixed with 25% O at a flow rate of 80mL/min₂Mixing (N)₂As an equilibrium gas) to produce HCHO gas at a concentration of 40 ppm. The conversion of formaldehyde was determined by measuring the concentration of HCHO in the inlet and outlet gas streams. The formaldehyde concentration was determined by phenol spectrophotometry as follows: first, a cumulative volume of 100mL of a gas stream containing HCHO was bubbled through a gas containing C₆H₄SN(CH₃)C＝NNH₂·HCl(1×10-⁴wt%, 5 mL); then, NH is added₄Fe(SO₄)₂·12H₂O (1 wt%, 0.4mL, dissolved in 0.1M HCl) and the mixture was left to stand in the dark for 15 minutes. HCHO concentrations were obtained by reading the absorbance at 630nm using a spectrophotometer and comparing the data to a standard curve.

Example 7

Weighing chloroplatinic acid, pouring into 10L of deionized water, and performing ultrasonic full dissolution to prepare a clear and transparent solution with the cobalt concentration of 5 mmol/L. 1000g of titanium oxide is taken out and paved, the platinum complex solution is injected into an atomizer, and the atomizer is started to ensure that the solution is uniformly deposited on the surface of the catalyst carrier material. Turning over the catalyst carrier material every about one hour and uniformly spreading again to ensure that the platinum element on the surface of the catalyst is uniformly dispersed. Until 10L of the solution was consumed, the catalyst precursor was collected and placed in a vacuum oven overnight at 60 ℃. Finally, the sample was calcined in an air atmosphere at a temperature of 400 ℃ for 2 h. So as to obtain the platinum catalyst for catalyzing and decomposing formaldehyde at room temperature.

Catalytic HCHO oxidation activity was evaluated in a fixed bed reactor with 300mg of catalyst. By using N at a flow rate of 20mL/min₂The mixture was passed through a 3 wt% aqueous formaldehyde solution and then mixed with 25% O at a flow rate of 80mL/min₂Mixing (N)₂As an equilibrium gas) to produce HCHO gas at a concentration of 40 ppm. The conversion of formaldehyde was determined by measuring the concentration of HCHO in the inlet and outlet gas streams. The formaldehyde concentration was determined by phenol spectrophotometry as follows: first, a cumulative volume of 100mL of a gas stream containing HCHO was bubbled through a gas containing C₆H₄SN(CH₃)C＝NNH₂·HCl(1×10-⁴wt%, 5 mL); then, NH is added₄Fe(SO₄)₂·12H₂O (1 wt%, 0.4mL, dissolved in 0.1M HCl) and the mixture was left to stand in the dark for 15 minutes. HCHO concentrations were obtained by reading the absorbance at 630nm using a spectrophotometer and comparing the data to a standard curve.