Process for the preparation of surface carbonation-modified iron-doped nickel oxide and method for the decomposition of ozone

Abstract

The present application relates to a kind of surface carbonation modified iron-doped nickel oxide preparation method and the method of decomposing ozone, the preparation method comprises the following steps: adding precipitant to the aqueous solution of nickel-containing iron precursor, hydrothermal reaction is carried out, precursor material nickel-iron layered double hydroxide is obtained, calcination, the aqueous solution of the obtained iron-doped nickel oxide and modifier is mixed uniformly, hydrothermal reaction is carried out;Wherein, the modifier is one or more of urea, ammonium carbonate, ammonium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, lithium carbonate, lithium bicarbonate, sodium hydroxide, potassium hydroxide and lithium hydroxide.The preparation method of the present application is simple, does not need special condition, and the iron-doped nickel oxide catalyst modified by surface carbonation is rich in active site, and can show high and stable ozone decomposition efficiency in high humidity or extremely high humidity environment.

Description

Technical Field

[0001] This invention belongs to the field of ozone catalytic decomposition technology, specifically relating to a method for preparing surface-carbonized modified iron-doped nickel oxide and a method for decomposing ozone. Background Technology

[0002] Ozone is a highly oxidizing atmospheric gas formed in the atmosphere through a series of complex photochemical reactions between nitrogen oxides and volatile organic pollutants. It is a significant secondary pollutant. Due to the infiltration of outdoor ozone and its release from indoor devices such as printers and air purifiers, the average indoor ozone concentration in most offices, schools, and other long-term workplaces still exceeds the standard. Long-term ozone exposure can cause harm to human health; therefore, addressing ozone pollution is of paramount importance.

[0003] In ozone decomposition, catalysts, typically composed of transition metal oxides, usually utilize oxygen vacancies as active sites for ozone adsorption and oxygen release. In humid environments with high water vapor content, water molecules and the hydroxyl groups formed by their dissociation and adsorption exhibit higher adsorption competitiveness for oxygen vacancies, easily causing blockage of reactive sites and leading to catalyst deactivation. The optimal humidity for human comfort is between 40% and 70%, meaning that high concentrations of water vapor are usually present in the air during practical applications. Therefore, ozone decomposition catalysts that retain high activity under high humidity conditions have broad application prospects.

[0004] There are two main ways to improve the moisture resistance of ozone decomposition catalysts: the first is to increase the overall hydrophobicity of the catalyst by introducing hydrophobic components, thereby protecting the active sites from adsorption and blockage by water molecules; the second, and most important, method is to increase the catalytic degradation activity of the catalyst itself by increasing the number of active sites. The second method can also be divided into two categories: one is to increase the oxygen vacancy concentration, and the other is to introduce new active sites, such as metal cation vacancies. In recent years, nickel-based catalysts, especially nickel-based bimetallic hydroxides, have exhibited good catalytic stability under high humidity conditions. On the surface of these catalysts, hydroxyl groups participate in the catalytic reaction, and water adsorption promotes the positive catalytic cycle to some extent, reducing deactivation caused by water molecule blockage, thus providing new possibilities for improving the moisture resistance of catalysts. However, research on nickel oxides in nickel-based catalysts is relatively limited, and related studies mainly focus on how to improve the dispersion of NiO on the support and how to increase the oxygen vacancy concentration.

[0005] CN117753423A discloses a method for preparing a catalyst capable of catalyzing the decomposition of ozone under high humidity. The method involves titrating solutions of nickel nitrate and ferric nitrate under an alkaline environment using a co-precipitation technique. Nitrogen gas is used to prevent carbon dioxide from interfering with the reaction in a zincate-intercalated hydrotalcite-like catalyst, and nitrogen protection is maintained throughout the titration process. Finally, ozone pretreatment is performed to obtain the catalyst product. By creating a hydrophobic layer through zincate intercalation and exposing more unsaturated oxygen sites through the pretreatment process, this catalyst can stably catalyze the decomposition of ozone under high humidity conditions. However, this preparation method is complex, requires nitrogen protection, and involves specific reaction conditions, which is not conducive to industrial application.

[0006] Therefore, developing a nickel-based oxide catalyst with a simple preparation process, rich in active sites, and capable of utilizing abundant water molecules in the environment, and exhibiting efficient and stable catalytic performance in high humidity environments, is of great significance for protecting people from the threat of ozone exposure. Summary of the Invention

[0007] The problem the invention aims to solve

[0008] This invention aims to provide a method for preparing surface-carbonated modified iron-doped nickel oxide and a method for decomposing ozone. The preparation method is simple, and the surface-carbonated modified iron-doped nickel oxide is rich in active sites, which can exhibit efficient and stable catalytic ozone decomposition performance in high humidity environments.

[0009] Solution for solving the problem

[0010] To address the above problems, the present invention provides the following technical solution:

[0011] [1] A method for preparing surface-carbonated modified iron-doped nickel oxide, comprising the following steps:

[0012] (1) Add a precipitant to an aqueous solution containing nickel-iron precursor and carry out a hydrothermal reaction to obtain the precursor nickel-iron layered bimetallic hydroxide. Calcine the precursor to obtain iron-doped nickel oxide.

[0013] (2) Mix the iron-doped nickel oxide obtained in step (1) with the aqueous solution of the modifier and carry out a hydrothermal reaction to obtain the surface carbonation modified iron-doped nickel oxide.

[0014] The modifier is one or more of urea, ammonium carbonate, ammonium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, lithium carbonate, lithium bicarbonate, sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0015] [2] According to the preparation method described in [1], the aqueous solution of the nickel-iron precursor contains nickel ions and ferrous ions; preferably, the molar ratio of nickel ions to ferrous ions is (2-20):1, more preferably (2-10):1, and more preferably (3-5):1.

[0016] [3] According to the preparation method described in [1] or [2], the precipitant includes one or more of urea, ammonium carbonate and ammonium bicarbonate; preferably, the molar ratio of the precipitant to the nickel-iron precursor is (2-3):1.

[0017] [4] According to any one of [1]-[3], in step (2), the ratio of the iron-doped nickel oxide to the modifier is 1g:(0.01-0.5)mol, preferably 1g:(0.03-0.1)mol.

[0018] [5] The preparation method according to any one of [1]-[4], wherein the nickel-iron precursor includes a nickel precursor and an iron precursor, the nickel precursor includes one or more of nickel nitrate, nickel chloride and nickel sulfate, and the iron precursor includes one or more of ferrous sulfate, ferrous chloride and ferrous nitrate; preferably, the total concentration of the aqueous solution of the nickel-iron precursor is 0.1-0.2 mol / L.

[0019] [6] According to any one of [1]-[5], in step (1), the calcination temperature is 350-600℃, preferably 400-500℃; the calcination time is 2-6h, preferably 2-4h; the calcination is carried out in an air or nitrogen atmosphere.

[0020] [7] According to any one of [1]-[6], in step (1) and step (2), the temperature of the hydrothermal reaction is 110-150℃, preferably 110-130℃; and the time of the hydrothermal reaction is 1-12h, preferably 3-6h.

[0021] [8] According to any one of [1]-[7], in step (1), after the hydrothermal reaction is completed, the obtained solid is washed with water and dried to obtain the precursor nickel-iron layered bimetallic hydroxide; preferably, the drying is carried out in an air atmosphere at 80-105°C;

[0022] In step (2), after the hydrothermal reaction is completed, the obtained solid is washed with water and dried to obtain the surface carbonation modified iron-doped nickel oxide; preferably, the drying is carried out in an air atmosphere at 60-80°C.

[0023] [9] Surface-carbonated modified iron-doped nickel oxide prepared according to any one of [1]-[8].

[0024]

[10] A method for decomposing ozone, comprising the steps of: decomposing ozone into oxygen under the catalysis of iron-doped nickel oxide with surface carbonation modification prepared according to any one of the preparation methods described in [1]-[8];

[0025] Preferably, the decomposition is carried out under conditions of relative humidity of 40%-100%, and more preferably under conditions of relative humidity of 50%-95%.

[0026] Preferably, the decomposition is carried out at 10-50°C, and more preferably at 15-30°C;

[0027] Preferably, the mass space velocity of the decomposed gas stream is 1000-5000 L / g·h, more preferably 1200-3000 L / g·h.

[0028] The effects of the invention

[0029] This invention has the following superior technical effects:

[0030] (1) The preparation method and modification method of the surface carbonation modified iron-doped nickel oxide of the present invention are simple and do not require special conditions. The solution used in the modification method is highly selective. Therefore, the method of the present invention has a large application space.

[0031] (2) The iron-doped nickel oxide catalyst modified by surface carbonation is rich in active sites and can exhibit high and stable ozone decomposition efficiency (especially at room temperature) under high or extremely high humidity environments (e.g., relative humidity above 50% or 90%). The iron-doped nickel oxide catalyst of the present invention can maintain an ozone decomposition efficiency of above 80%, above 90%, above 95%, or above 97% for up to 10 hours or even 60 hours.

[0032] (3) After surface carbonation modification and ozone catalysis, the crystal structure of the iron-doped nickel oxide catalyst did not change significantly, indicating that the crystal structure of the iron-doped nickel oxide catalyst of the present invention has good crystallinity and stability. Attached Figure Description

[0033] Figure 1 X-ray diffraction crystal structures of nickel-iron layered bimetallic hydroxide precursor, iron-doped nickel oxide Cat 1, surface-carbonized modified catalyst Cat 2, and Cat 1 and Cat 2 after ozone catalysis.

[0034] Figure 2Scanning electron microscope images of nickel-iron layered bimetallic hydroxide precursor (a), iron-doped nickel oxide Cat 1 (b), and surface-carbonized modified catalyst Cat 2 (c).

[0035] Figure 3 Transmission electron microscope (TEM) images of iron-doped nickel oxide Cat 1(a) and surface-carbonated modified catalyst Cat 2(d); high-resolution TEM images of iron-doped nickel oxide Cat 1(b) and surface-carbonated modified catalyst Cat 2(e); high-resolution TEM images of iron-doped nickel oxide Cat 1(c) and surface-carbonated modified catalyst Cat 2(f) after ozone catalysis.

[0036] Figure 4 The graph shows the performance of catalysts Cat 1 and Cat 2 in catalytic decomposition of ozone at room temperature under different relative humidity conditions.

[0037] Figure 5 The graph shows the performance of room temperature catalytic decomposition of ozone on nickel oxide surfaces before and after carbonation with different iron doping contents.

[0038] Figure 6 Scanning electron microscope images of catalysts modified by carbonation on the surface of nickel oxides with different iron doping contents.

[0039] Figure 7 The graph shows the performance of samples at different stages of the decarbonization and secondary surface carbonization of catalyst Cat 2 during room temperature catalytic decomposition of ozone.

[0040] Figure 8 The above figures show the results of in-situ infrared spectroscopy tests of catalysts Cat 1, Cat 11, and Cat 14 under elevated temperatures.

[0041] Figure 9 The image shows the in-situ infrared test results of ozone on catalysts Cat 1 and Cat 14 under high humidity conditions.

[0042] Figure 10 The graphs show the performance of surface-carbonated catalysts Cat 2, Cat 11, Cat 14, and Cat 15 in catalytic decomposition of ozone at room temperature.

[0043] Figure 11 The graph shows the performance of the surface-carbonized modified catalyst Cat 16 in the long-term room temperature catalytic decomposition of ozone. Detailed Implementation

[0044] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment illustrated herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0045] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0046] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0047] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0048] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0049] In this specification, the range of values ​​referred to as “value A - value B” is the range that includes the endpoint values ​​A and B.

[0050] In this specification, the range of values ​​referred to as "value A and above" refers to the range including the endpoint value A.

[0051] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15-30℃, or more specifically 15-25℃, such as 20℃.

[0052] In this invention, "iron-doped nickel oxide" means "iron-doped nickel oxide".

[0053] In this invention, the catalyst refers to "surface carbonation modified iron-doped nickel oxide catalyst", that is, "surface carbonation modified iron-doped nickel oxide".

[0054] This invention provides a method for preparing surface-carbonated modified iron-doped nickel oxide. In this invention, "surface carbonation" refers to adding carbonate species to the surface of the iron-doped nickel oxide. The surface-carbonated modified iron-doped nickel oxide catalyst can achieve efficient and stable room-temperature ozone catalytic decomposition under high humidity or extremely high humidity conditions, enabling ozone to be rapidly and safely converted into harmless oxygen under the action of the catalyst.

[0055] Preparation method of surface carbonation modified iron-doped nickel oxide

[0056] The preparation method of surface-carbonated modified iron-doped nickel oxide provided by this invention has a simple process flow and specifically includes the following steps:

[0057] (1) Add a precipitant to an aqueous solution containing nickel-iron precursor and carry out a hydrothermal reaction to obtain the precursor nickel-iron layered bimetallic hydroxide. Calcine the precursor to obtain iron-doped nickel oxide.

[0058] (2) Mix the iron-doped nickel oxide obtained in step (1) with the aqueous solution of the modifier and carry out a hydrothermal reaction to obtain the surface carbonation modified iron-doped nickel oxide.

[0059] The modifier is one or more of urea, ammonium carbonate, ammonium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, lithium carbonate, lithium bicarbonate, sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0060] In some embodiments, the aqueous solution of the modifier can be an aqueous solution containing carbonate ions, such as urea aqueous solution, ammonium carbonate aqueous solution, ammonium bicarbonate aqueous solution, sodium carbonate aqueous solution, sodium bicarbonate aqueous solution, potassium carbonate aqueous solution, potassium bicarbonate aqueous solution, lithium carbonate aqueous solution, lithium bicarbonate aqueous solution, etc., which can directly or after heating in a hydrothermal reaction to provide carbonate ions for the modification of iron-doped nickel oxide. For example, urea aqueous solution can provide carbonate ions through hydrolysis in a hydrothermal reaction.

[0061] In other embodiments, the aqueous solution of the modifier can be an aqueous solution of an alkali metal hydroxide, such as sodium hydroxide, potassium hydroxide, or lithium hydroxide. This enhances the alkalinity of the environment surrounding the iron-doped nickel oxide, allowing it to adsorb carbonate species or carbon dioxide from the aqueous phase, or to adsorb carbonate species or carbon dioxide from the air during the drying process. Experimental verification shows that when the aqueous solution of the modifier is an aqueous solution of alkali metal sodium hydroxide (e.g., the catalyst Cat 11 in the examples), the surface of the modified iron-doped nickel oxide also possesses abundant carbonate species and exhibits highly efficient and stable ozone catalytic decomposition efficiency.

[0062] In this invention, the concentration of the aqueous solution of the modifier is not particularly limited, as long as it can carbonize the surface of iron-doped nickel oxide, thereby improving the ozone catalytic decomposition efficiency. In some embodiments, the concentration of the aqueous solution of the modifier can be 0.1-0.5 mol / L, for example, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, etc.

[0063] In this invention, the amount of the modifier added is not particularly limited, as long as it can carbonize the surface of iron-doped nickel oxide, thereby improving the ozone catalytic decomposition efficiency. In some embodiments, in step (2), the ratio of the iron-doped nickel oxide to the modifier is 1g:(0.01-0.5)mol, preferably 1g:(0.03-0.1)mol, for example 1g:0.02mol, 1g:0.04mol, 1g:0.05mol, 1g:0.06mol, 1g:0.08mol, 1g:0.15mol, 1g:0.2mol, 1g:0.3mol, etc.

[0064] In some embodiments, the precipitant may include one or more of urea, ammonium carbonate, and ammonium bicarbonate.

[0065] In some implementations, the precipitant in step (1) can provide ammonium ions in the aqueous solution, which can precipitate nickel ions and ferrous ions in the aqueous solution containing the nickel-iron precursor, thereby converting the nickel ions and ferrous ions into metal hydroxides.

[0066] In this invention, the amount of precipitant added is not particularly limited, as long as it can precipitate nickel and ferrous ions in the aqueous solution of the nickel-iron precursor. In some embodiments, the molar ratio of the precipitant to the nickel-iron precursor is (2-3):1, for example, 2.5:1.

[0067] In some embodiments, the aqueous solution of the nickel-iron precursor contains nickel ions and ferrous ions. In some specific embodiments, the molar ratio of nickel ions to ferrous ions is (2-20):1, preferably (2-15):1, more preferably (2-10):1, or (3-10):1, or (3-5):1, for example 2.5:1, 4:1, 6:1, 7:1, 8:1, 11:1, 12:1, 14:1, etc.

[0068] In some embodiments, the nickel-iron precursor includes a nickel precursor and an iron precursor, wherein the nickel precursor includes one or more of nickel nitrate, nickel chloride, and nickel sulfate, and the iron precursor includes one or more of ferrous sulfate, ferrous chloride, and ferrous nitrate.

[0069] In this invention, the concentration of the aqueous solution of the nickel-iron precursor is not particularly limited. In some embodiments, the total concentration of the aqueous solution of the nickel-iron precursor is 0.1-0.2 mol / L, preferably 0.1-0.15 mol / L, such as 0.11 mol / L, 0.12 mol / L, 0.14 mol / L, 0.16 mol / L, 0.18 mol / L, etc.

[0070] In some implementations, the calcination temperature in step (1) is 350-600°C, preferably 400-500°C, such as 375°C, 450°C, 525°C, 550°C, etc.

[0071] In some implementations, the calcination time in step (1) is 2-6 hours, preferably 2-4 hours, such as 3 hours, 5 hours, etc.

[0072] In some embodiments, the calcination in step (1) is carried out in an air or nitrogen atmosphere. In some specific embodiments, the calcination in step (1) is carried out in air.

[0073] In some embodiments, in step (1), the temperature of the hydrothermal reaction is 110-150°C, preferably 110-130°C, such as 115°C, 120°C, 125°C, 140°C, etc. In some embodiments, in step (1), the time of the hydrothermal reaction is 1-12 hours, preferably 3-12 hours, more preferably 3-6 hours, such as 4 hours, 5 hours, 7 hours, 8 hours, 10 hours, etc.

[0074] In some embodiments, in step (2), the temperature of the hydrothermal reaction is 110-150°C, preferably 110-130°C, such as 115°C, 120°C, 125°C, 140°C, etc. In some embodiments, in step (1), the time of the hydrothermal reaction is 1-12 hours, preferably 3-12 hours, more preferably 3-6 hours, such as 4 hours, 5 hours, 7 hours, 8 hours, 10 hours, etc.

[0075] In some embodiments, after the hydrothermal reaction in step (1) is completed, the obtained solid is washed with water and dried to obtain the precursor nickel-iron layered bimetallic hydroxide. In some preferred embodiments, the drying is carried out in an air atmosphere at 80-105°C (e.g., 85°C, 90°C, 100°C, etc.).

[0076] In some embodiments, after the hydrothermal reaction in step (2), the obtained solid is washed with water and dried to obtain the surface-carbonated modified iron-doped nickel oxide. In some preferred embodiments, the drying is carried out in an air atmosphere at 60-80°C (e.g., 65°C, 70°C, 75°C, etc.).

[0077] In some implementations, the water is one or more of deionized water, purified water, or distilled water.

[0078] Surface carbonation modified iron-doped nickel oxide catalyst

[0079] The present invention also provides a surface-carbonated modified iron-doped nickel oxide catalyst, which is prepared by the above preparation method.

[0080] In some embodiments, the inorganic carbon content of the surface-carbonized modified iron-doped nickel oxide of the present invention is 0.2 wt% or more, preferably 0.3 wt% or more, for example 0.4 wt%, 0.5 wt%, 0.6 wt%, 1 wt%, 2 wt%, etc.

[0081] A method for decomposing ozone using surface-carbonated modified iron-doped nickel oxide catalysts

[0082] The surface-carbonated modified iron-doped nickel oxide catalyst provided by this invention can efficiently and stably catalyze the decomposition of ozone into oxygen under high humidity or extremely high humidity conditions. The surface-carbonated modified iron-doped nickel oxide catalyst prepared according to the above preparation method can be applied to ozone decomposition.

[0083] Therefore, the present invention also provides a method for decomposing ozone, comprising the following steps: ozone is decomposed into oxygen under the catalysis of iron-doped nickel oxide with surface carbonation modification prepared according to the above preparation method.

[0084] In this invention, the decomposition can be carried out at any humidity level, i.e., the decomposition can be carried out under conditions of relative humidity of 0%-100%. In some embodiments, the decomposition is carried out under conditions of high humidity. In some preferred embodiments, the decomposition is carried out under conditions of relative humidity of 40%-100%, preferably 50%-95% (e.g., 60%, 70%, 80%, 90%, etc.).

[0085] In this invention, the decomposition temperature is not particularly limited. In some embodiments, the decomposition is carried out at 10-50°C. In some preferred embodiments, the decomposition is carried out at 15-30°C (e.g., 20°C, 25°C, 28°C, etc.).

[0086] In this invention, the mass hourly space velocity (MHSV) of the decomposed gas stream is not particularly limited. In some embodiments, the MHSV is 1000-5000 L / g·h. In some preferred embodiments, the MHSV is 1200-3000 L / g·h, such as 1500 L / g·h, 2000 L / g·h, 2500 L / g·h, etc.

[0087] Ozone removal efficiency (decomposition efficiency) test method

[0088] The performance of the catalyst of this invention was tested in a quartz tube with a diameter of 6 mm at room temperature (25°C). The catalyst used in the experiment consisted of 20-50 mg of 40-60 mesh powder. The ozone used in the experiment was generated by irradiating O2 gas with a low-pressure mercury ultraviolet lamp with a wavelength of 185 nm, and the ozone concentration was approximately 100 ppm. The total flow rate of the test gas was set to 1 L / min. The relative humidity (RH) was controlled by adjusting the flow rate of the wet and dry channels using a mass flow meter and measured using a relative humidity meter (testo635-2); for example, a relative humidity of RH = 90% means a wet gas flow rate of 900 mL / min and a dry gas flow rate of 100 mL / min. An online ozone analyzer (model 49i, Thermo Fisher Scientific, USA) was used to detect the ozone concentration in real time, recording it once per minute with an accuracy of ±1 ppb. The formula for calculating the ozone removal rate is as follows:

[0089]

[0090] In the formula [O3] in and [O3] out These are the real-time ozone concentrations at the reactor inlet and outlet, recorded by the analyzer.

[0091] Example

[0092] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0093] Comparative Example 1

[0094] 6 mmol of nickel nitrate and 2 mmol of ferrous sulfate were added to 70 mL of deionized water and magnetically stirred for 5 min at room temperature to ensure homogeneity. Then, 20 mmol of urea was added to the homogeneous solution, and the mixture was sonicated for 5 min followed by magnetic stirring for another 5 min to further homogenize it. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 120 °C for 12 h. The resulting sample was washed with deionized water and dried at 80 °C to obtain the precursor, nickel-iron layered bimetallic hydroxide. The precursor was pulverized evenly in a mortar and placed in a crucible, then heated to 400 °C at a rate of 5 °C / min and calcined for 2 h in a tube furnace under a synthesis air atmosphere to obtain iron-doped nickel oxide Cat 1.

[0095] Example 1

[0096] Add 6 mmol of nickel nitrate and 2 mmol of ferrous sulfate to 70 mL of deionized water and stir magnetically for 5 min at room temperature to mix the solution evenly. Then add 20 mmol of urea to the evenly mixed solution, sonicate for 5 min and stir magnetically for 5 min to further mix the solution evenly. Transfer the mixed solution to a hydrothermal reactor and react hydrothermally at 120 °C for 12 h. The obtained sample is washed with deionized water and dried at 80 °C to obtain the precursor nickel-iron layered bimetallic hydroxide. The precursor was pulverized evenly in a mortar and placed in a crucible. It was heated to 400°C at a rate of 5°C / min and calcined for 2 hours in a synthesis air atmosphere in a tube furnace to obtain iron-doped nickel oxide. 0.15 g of iron-doped nickel oxide was placed in 70 mL of an aqueous solution containing 0.1 M urea, sonicated for 5 min, and magnetically stirred for 5 min to mix the solution evenly. The mixed solution was transferred to a hydrothermal reactor and hydrothermally treated at 120°C for 6 hours. The obtained sample was washed with deionized water and dried overnight at 80°C to obtain surface-carbonated modified iron-doped nickel oxide Cat 2.

[0097] Figure 1 X-ray diffraction (XRD) crystal structure images of samples at each stage of the reaction (nickel-iron layered bimetallic hydroxide precursor, iron-doped nickel oxide Cat 1, and catalyst Cat 2 after surface carbonation modification) and the catalyst sample after ozone catalysis. The precursor exhibits a typical nickel-iron layered bimetallic hydroxide structure, consistent with the XRD standard card PDF#40-0215 ​​for LDH (nickel-iron layered bimetallic hydroxide); the other samples all exhibit typical nickel oxide crystal structures, consistent with the XRD standard card PDF#47-1049 for NiO. No iron-related peaks were observed, indicating that iron atoms were successfully doped into the nickel oxide lattice. The crystal structure of the iron-doped nickel oxide catalyst did not change significantly after surface carbonation modification and after ozone catalysis, indicating good crystallinity and stability.

[0098] Figure 2 Scanning electron microscope images of nickel-iron layered bimetallic hydroxide precursor (a), iron-doped nickel oxide Cat 1 (b), and surface-carbonized modified catalyst Cat 2 (c). Figure 3Transmission electron microscopy (TEM) images and high-resolution images of iron-doped nickel oxide Cat 1 (a)(b), surface-carbonated modified catalyst Cat 2 (d)(e), and samples (c) and (f) after ozone catalytic decomposition of their respective ozone atoms are shown. The microstructure of the iron-doped nickel oxide catalyst did not change significantly after surface carbonation modification and ozone catalytic reaction, consisting of flower-like spheres with a diameter of 600 nm formed by intercalated nanosheets. The nanosheets have good crystallinity, with main interplanar spacings of 2.45 nm and 2.10 nm (marked in yellow), corresponding to the interplanar spacings of NiO (111) and (200), respectively, and interplanar angles of 55°. The samples are exposed... After the ozone catalytic reaction, the crystallinity of the catalyst decreased slightly, and some small amorphous regions appeared (marked with red circles). This is the main exposure The flower-shaped structure of the crystal facets provides abundant exposure of active sites for the catalyst, thereby improving its performance.

[0099] Figure 4 The figures show the performance of catalysts Cat 1 and Cat 2 in catalytic ozone decomposition at room temperature under different relative humidity conditions. The test conditions were 25℃, inlet ozone concentration of 100 ppm, catalyst dosage of 20 mg, gas mass hourly space velocity (GHSV) of 3000 L / g·h, and relative humidity of 0%, 30%, 50%, 70%, and 90%. Cat 1 exhibited stable high ozone catalytic activity under dry gas conditions (RH = 0%), maintaining an ozone removal rate of over 95% after 10 hours; however, under high humidity conditions (RH > 90%), its catalytic conversion rate decreased to approximately 32%. The surface-carbonized sample Cat 2 maintained an ozone removal rate of over 83% after 10 hours under high humidity conditions. Compared to Cat 1, the decomposition ability of Cat 2 catalyst was more stable under higher relative humidity conditions (RH > 50%), without a significant decrease. The performance of this sample in catalytic ozone decomposition under high humidity conditions showed a clear gradual improvement process, gradually stabilizing. This indicates that the sample surface after carbonation undergoes a complex activation reaction in the presence of both ozone and water, and the newly generated components after activation have a more efficient and stable room temperature ozone removal efficiency under high humidity conditions.

[0100] Cat 2 was subjected to long-term ozone catalytic decomposition at 25℃, with an inlet ozone concentration of 100 ppm, a catalyst dosage of 50 mg, a gas flow mass hourly velocity of 1200 L / g·h, and RH = 90%. The results are shown in [Figure Number]. Figure 10 Catalyst Cat 2 can maintain approximately 97% of its catalytic decomposition performance for over 10 hours. Test results indicate that the surface-carbonated modified iron-doped nickel oxide catalyst prepared in this invention exhibits highly efficient and stable ozone decomposition capabilities under extremely high humidity conditions.

[0101] Example 2

[0102] Add 8 mmol of nickel nitrate (or 7.27 mmol of nickel nitrate and 0.73 mmol of ferrous sulfate, or 6 mmol of nickel nitrate and 2 mmol of ferrous sulfate, or 5.33 mmol of nickel nitrate and 2.67 mmol of ferrous sulfate) to 70 mL of deionized water and stir magnetically for 5 min at room temperature to mix the solution evenly. Then add 20 mmol of urea to the mixed solution, sonicate for 5 min and stir magnetically for 5 min to further mix the solution evenly. Transfer the mixed solution to a hydrothermal reactor and react hydrothermally at 120 °C for 12 h. The obtained sample is washed with deionized water and dried at 80 °C to obtain the precursor nickel-iron layered bimetallic hydroxide. The precursor was pulverized evenly in a mortar and placed in a crucible. It was heated to 400°C at a rate of 5°C / min and calcined for 2 hours in a synthesis air atmosphere in a tube furnace to obtain iron-doped nickel oxide Cat3-6. 0.15 g of iron-doped nickel oxide was placed in 70 mL of aqueous solution containing 0.1 M urea, sonicated for 5 min, and magnetically stirred for 5 min to mix the solution evenly. The mixed solution was transferred to a hydrothermal reactor and hydrothermally treated at 120°C for 6 hours. The obtained sample was washed with deionized water and dried overnight at 80°C to obtain surface-carbonated modified nickel oxides with different iron contents, Cat7-10. Among them, Cat3 and 7 were iron-free samples, Cat4 and 8 had Ni / Fe = 10, Cat5 and 9 had Ni / Fe = 3, and Cat6 and 10 had Ni / Fe = 2.

[0103] Figure 5 The figure shows the performance of Cat 3-10 catalyst in the room temperature catalytic decomposition of ozone. The test conditions were 25℃, inlet ozone concentration of 100ppm, catalyst dosage of 20mg, gas flow hourly space velocity of 3000L / g·h, and relative humidity of 90%. It is evident that iron doping significantly enhances the catalytic activity of nickel oxide and the activity of the catalyst obtained through further surface carbonation; Ni / Fe = 3 is the most suitable ratio.

[0104] Figure 6 Scanning electron microscope (SEM) images of carbonized nickel oxide samples with different iron doping contents. In the pure Ni phase, the catalyst exhibits a microsphere composed of very small bands or plates. With a small amount of Fe doping, this small structure becomes plate-like, and larger plates begin to form flower-like structures. As the doping concentration increases, the plates grow, and the overall diameter of the flower-like structures increases. When the Ni / Fe ratio reaches 3, the small plate-like structures essentially disappear, and the overall flower-like structure becomes uniform and complete. At Ni / Fe = 2, due to excessive Fe doping, the flower-like structure collapses after the plates thicken. The results suggest that the presence of iron facilitates the exposure of a specific crystal plane. Figure 3 It can be seen that the exposed crystal plane is This also illustrates Crystal facets can expose abundant active sites in catalysts, thereby improving catalyst performance.

[0105] Example 3

[0106] Add 6 mmol of nickel nitrate and 2 mmol of ferrous sulfate to 70 mL of deionized water and stir magnetically for 5 min at room temperature to mix the solution evenly. Then add 20 mmol of urea to the evenly mixed solution, sonicate for 5 min and stir magnetically for 5 min to further mix the solution evenly. Transfer the mixed solution to a hydrothermal reactor and react hydrothermally at 120 °C for 12 h. The obtained sample is washed with deionized water and dried at 80 °C to obtain the precursor nickel-iron layered bimetallic hydroxide. The precursor was pulverized evenly in a mortar and placed in a crucible. It was heated to 400°C at a rate of 5°C / min and calcined for 2 hours in a tube furnace under a synthesis air atmosphere to obtain iron-doped nickel oxide. 0.15 g of the iron-doped nickel oxide was placed in 70 mL of an aqueous solution containing 0.1 M sodium hydroxide, sonicated for 5 minutes, and then magnetically stirred for 5 minutes to ensure homogeneity. The mixed solution was transferred to a hydrothermal reactor and hydrothermally treated at 120°C for 6 hours. The resulting sample was washed with deionized water and dried overnight at 80°C to obtain surface-carbonated modified iron-doped nickel oxide Cat 11. Cat 11 was subjected to long-term ozone catalytic decomposition at 25°C, an inlet ozone concentration of 100 ppm, a catalyst dosage of 50 mg, a gas flow hourly space velocity of 1200 L / g·h, and RH = 90%. The results are shown in [Figure number missing]. Figure 10 The catalyst Cat11 can maintain approximately 97% of its catalytic decomposition performance for over 10 hours. Test results indicate that the surface-carbonated modified iron-doped nickel oxide catalyst prepared in this invention exhibits highly efficient and stable ozone decomposition capabilities under extremely high humidity conditions.

[0107] Table 1 shows the carbon content of the samples before and after surface carbonization. Inorganic carbon was determined using a Total Organic Carbon Analyzer (TOC-L). The total carbon (TC) content was determined by the mass of CO2 removed from the sample during high-temperature combustion at 900℃, and the inorganic carbon (IC) content was determined by the mass of CO2 removed by dissolving the sample in phosphoric acid and heating at 200℃. Organic carbon (TOC) was the difference between the two (TC% - IC%). The precursor removed a large amount of carbon during calcination, reducing the total carbon (TC) content of Cat 1 to 0.17%, with inorganic carbon (IC) being the predominant form. After surface carbonization, the TC content of the catalyst increased significantly, again primarily due to an increase in inorganic carbon. The inorganic carbon content is positively correlated with performance, indicating that the abundant carbonate species in the sample after surface carbonization are beneficial for ozone catalytic decomposition.

[0108] Table 1. Carbon content (wt%) of samples before and after surface carbonization

[0109]

[0110] Example 4

[0111] Catalyst Cat 2 prepared in Example 1 was subjected to ozone catalysis for 3 hours at 25°C, with an inlet ozone concentration of 100 ppm, a catalyst dosage of 20 mg, a gas flow mass hourly velocity of 3000 L / g·h, and RH = 90%, and the performance was recorded. The sample after the catalytic reaction was placed in an oven and heated at 80°C for 6 hours to remove carbonates and other active components such as surface-adsorbed active oxygen obtained after activation, yielding Cat 12. Cat 12 was subjected to ozone catalysis under the same conditions, and its performance was recorded. 0.15 g of Cat 12 was placed in 70 mL of an aqueous solution containing 0.1 M urea, sonicated for 5 minutes, and magnetically stirred for 5 minutes to ensure uniform mixing. The mixed solution was transferred to a hydrothermal reactor and hydrothermally treated at 120°C for 6 hours. The resulting sample was washed with deionized water and dried overnight at 80°C to obtain iron-doped nickel oxide Cat 13 after secondary surface carbonation modification. Cat 13 was subjected to ozone catalysis under the same conditions, and its performance was recorded.

[0112] Figure 7 These are the performance results of the catalysts at each stage for room temperature catalytic decomposition of ozone. The sample after heating to 80℃ to remove the active components still requires an activation time, and its ozone decomposition performance significantly decreases upon reaching a stable stage after activation. This may be because some carbonate is consumed during the first activation stage, reducing the carbonate content in the catalyst and thus decreasing the effectiveness of subsequent ozone activation. However, the performance of the sample after re-surface carbonation treatment is restored, further confirming that the abundant carbonate on the catalyst surface after surface carbonation modification plays a crucial role in the catalyst's activity.

[0113] Example 5

[0114] Add 6 mmol of nickel nitrate and 2 mmol of ferrous sulfate to 70 mL of deionized water and stir magnetically for 5 min at room temperature to mix the solution evenly. Then add 20 mmol of urea to the evenly mixed solution, sonicate for 5 min and stir magnetically for 5 min to further mix the solution evenly. Transfer the mixed solution to a hydrothermal reactor and react hydrothermally at 120 °C for 12 h. The obtained sample is washed with deionized water and dried at 80 °C to obtain the precursor nickel-iron layered bimetallic hydroxide. The precursor was pulverized evenly in a mortar and placed in a crucible. It was heated to 400°C at a rate of 5°C / min and calcined for 2 hours in a tube furnace under a synthesis air atmosphere to obtain iron-doped nickel oxide. 0.15 g of the iron-doped nickel oxide was placed in 70 mL of an aqueous solution containing 0.1 M ammonium carbonate or 0.1 M sodium carbonate, sonicated for 5 minutes, and then magnetically stirred for 5 minutes to ensure homogeneity. The mixed solution was transferred to a hydrothermal reactor and hydrothermally treated at 120°C for 6 hours. The resulting sample was washed with deionized water and dried overnight at 80°C to obtain surface-carbonated modified iron-doped nickel oxides Cat 14 and Cat 15. Cat 14 and Cat 15 were subjected to long-term ozone catalytic decomposition at 25°C, an inlet ozone concentration of 100 ppm, a catalyst dosage of 50 mg, a gas flow hourly space velocity of 1200 L / g·h, and RH = 90%. The results are shown in [Figure number missing]. Figure 10 Catalysts Cat 14 and Cat 15 can maintain approximately 97% of their catalytic decomposition performance for over 10 hours. Test results indicate that the surface-carbonated modified iron-doped nickel oxide catalyst prepared in this invention exhibits highly efficient and stable ozone decomposition capabilities under extremely high humidity conditions.

[0115] Figure 8 These are the results of in-situ infrared spectroscopy measurements of catalysts Cat 1, Cat 11, and Cat 14 during temperature-induced desorption. The characteristic peaks for temperature-induced desorption of the catalysts in air are located in the 750-970 cm⁻¹ range. -1 1045-1069cm -1 1285-1475cm -1 Classified as CO3 2- 1650cm -1 Left and right and 3400cm -1 The δ(H2O) and v(OH) are attributed to H2O. The results show that the inorganic carbonate species and water content on the catalyst surface both increased after modification.

[0116] Figure 9These are in-situ infrared spectroscopy results for ozone on catalysts Cat 1 and Cat 14 under high humidity conditions (RH 100%). Cat 1 shows strong characteristic peaks for peroxide species and weak shear vibration peaks for hydrogen peroxide species, indicating significant accumulation of ozone decomposition intermediates in Cat 1, which is absent in the surface-carbonized sample. The water adsorption characteristic peaks on Cat 14 are significantly weaker than those on Cat 1, and an additional δ-water adsorption characteristic peak appears on Cat 1. These results indicate that the surface-carbonized sample exhibits almost no accumulation of ozone decomposition intermediates during ozone decomposition under high humidity conditions, and water adsorption is also greatly reduced. This further explains, from a microscopic perspective, why surface carbonization modification of iron-doped nickel oxide catalysts is beneficial for ozone decomposition under high humidity conditions.

[0117] Example 6

[0118] Add 6 mmol of nickel nitrate and 2 mmol of ferrous sulfate to 70 mL of deionized water and stir magnetically for 5 min at room temperature to mix the solution evenly. Then add 20 mmol of urea to the evenly mixed solution, sonicate for 5 min and stir magnetically for 5 min to further mix the solution evenly. Transfer the mixed solution to a hydrothermal reactor and react hydrothermally at 120 °C for 12 h. The obtained sample is washed with deionized water and dried at 80 °C to obtain the precursor nickel-iron layered bimetallic hydroxide. The precursor was pulverized evenly in a mortar and placed in a crucible. It was heated to 500°C at a rate of 5°C / min and calcined for 2 hours in a synthesis air atmosphere in a tube furnace to obtain iron-doped nickel oxide. 0.15 g of iron-doped nickel oxide was placed in 70 mL of an aqueous solution containing 0.1 M urea, sonicated for 5 min, and magnetically stirred for 5 min to mix the solution evenly. The mixed solution was transferred to a hydrothermal reactor and hydrothermally treated at 120°C for 6 hours. The obtained sample was washed with deionized water and dried overnight at 80°C to obtain surface-carbonated modified iron-doped nickel oxide Cat 16.

[0119] Figure 11 The results show the performance of catalyst Cat 16 under long-term ozone catalytic decomposition conditions at 25℃, inlet ozone concentration of 100ppm, catalyst dosage of 50mg, gas mass hourly space velocity of 1200L / g·h, and RH = 90%. The catalyst can maintain approximately 97% of its catalytic decomposition performance for more than 30 hours. The test results indicate that the surface carbonation modified iron-doped nickel oxide catalyst prepared in this invention has a highly efficient and stable ozone decomposition capability under extremely high humidity conditions.

[0120] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0121] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing surface-carbonated modified iron-doped nickel oxide, comprising the following steps: (1) Add a precipitant to an aqueous solution containing nickel-iron precursor and carry out a hydrothermal reaction to obtain the precursor nickel-iron layered bimetallic hydroxide, which is then calcined to obtain iron-doped nickel oxide. (2) Mix the iron-doped nickel oxide obtained in step (1) with the aqueous solution of the modifier and carry out a hydrothermal reaction to obtain the surface carbonation modified iron-doped nickel oxide. wherein The modifier is one or more of urea, ammonium carbonate, ammonium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, lithium carbonate, lithium bicarbonate, sodium hydroxide, potassium hydroxide, and lithium hydroxide.

2. The preparation method according to claim 1, characterized in that, The aqueous solution of the nickel-iron precursor contains nickel ions and ferrous ions.

3. The preparation method according to claim 2, characterized in that, The molar ratio of nickel ions to ferrous ions is (2-20):

1.

4. The preparation method according to claim 3, characterized in that, The molar ratio of nickel ions to ferrous ions is (2-10):

1.

5. The preparation method according to claim 4, characterized in that, The molar ratio of nickel ions to ferrous ions is (3-5):

1.

6. The preparation method according to any one of claims 1-5, characterized in that, The precipitant includes one or more of urea, ammonium carbonate, and ammonium bicarbonate.

7. The preparation method according to claim 6, characterized in that, The molar ratio of the precipitant to the nickel-iron precursor is (2-3):

1.

8. The preparation method according to any one of claims 1-5, characterized in that, In step (2), the ratio of the iron-doped nickel oxide to the modifier is 1g:(0.01-0.5)mol.

9. The preparation method according to claim 8, characterized in that, In step (2), the ratio of the iron-doped nickel oxide to the modifier is 1 g:(0.03-0.1) mol.

10. The preparation method according to any one of claims 1-5, characterized in that, The nickel-iron precursor includes a nickel precursor and an iron precursor. The nickel precursor includes one or more of nickel nitrate, nickel chloride, and nickel sulfate, and the iron precursor includes one or more of ferrous sulfate, ferrous chloride, and ferrous nitrate.

11. The preparation method according to claim 10, characterized in that, The total concentration of the aqueous solution of the nickel-iron precursor is 0.1-0.2 mol / L.

12. The preparation method according to any one of claims 1-5, characterized in that, In step (1), the calcination temperature is 350-600℃; the calcination time is 2-6 h; and the calcination is carried out in an air or nitrogen atmosphere.

13. The preparation method according to claim 12, characterized in that, In step (1), the calcination temperature is 400-500℃.

14. The preparation method according to claim 12, characterized in that, In step (1), the calcination time is 2-4 h.

15. The preparation method according to any one of claims 1-5, characterized in that, In steps (1) and (2), the temperature of the hydrothermal reaction is 110-150℃; the time of the hydrothermal reaction is 1-12h.

16. The preparation method according to claim 15, characterized in that, In steps (1) and (2), the temperature of the hydrothermal reaction is 110-130℃.

17. The preparation method according to claim 15, characterized in that, In steps (1) and (2), the hydrothermal reaction takes 3-6 hours.

18. The preparation method according to any one of claims 1-5, characterized in that, In step (1), after the hydrothermal reaction is completed, the obtained solid is washed with water and dried to obtain the precursor nickel-iron layered bimetallic hydroxide. In step (2), after the hydrothermal reaction is completed, the obtained solid is washed with water and dried to obtain the surface carbonation modified iron-doped nickel oxide.

19. The preparation method according to claim 18, characterized in that, In step (1), the drying is carried out in an air atmosphere at 80-105°C.

20. The preparation method according to claim 18, characterized in that, In step (2), the drying is carried out in an air atmosphere at 60-80°C.

21. Surface-carbonated modified iron-doped nickel oxide prepared by the preparation method according to any one of claims 1-20.

22. A method of decomposing ozone comprising the steps of: Ozone decomposes into oxygen under the catalysis of surface-carbonated modified iron-doped nickel oxide prepared by the preparation method according to any one of claims 1-20.

23. The method according to claim 22, characterized in that, The decomposition was carried out under conditions of relative humidity of 40%-100%.

24. The method according to claim 23, characterized in that, The decomposition was carried out under conditions of relative humidity of 50%-95%.

25. The method according to claim 22, characterized in that, The decomposition was carried out at 10-50°C.

26. The method according to claim 25, characterized in that, The decomposition was carried out at 15-30°C.

27. The method according to claim 22, characterized in that, The mass hourly space velocity of the decomposed gas stream is 1000-5000 L / g·h.

28. The method according to claim 27, characterized in that, The mass hourly space velocity of the decomposed gas stream is 1200-3000 L / g·h.

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