CN111167432A

CN111167432A - A kind of cerium oxide-hydrotalcite composite catalyst, preparation method and application

Info

Publication number: CN111167432A
Application number: CN202010143898.3A
Authority: CN
Inventors: 李宏林; 高华敏; 蔡昌武; 胡梦娟; 唐梓涵
Original assignee: Chaohu University
Current assignee: Chaohu University
Priority date: 2020-03-04
Filing date: 2020-03-04
Publication date: 2020-05-19

Abstract

The invention belongs to the technical field of materials, and relates to a cerium oxide-hydrotalcite composite catalyst, a preparation method and an application. The cerium oxide-hydrotalcite composite catalyst of the invention is that cerium oxide nanoparticles are distributed on the hydrotalcite sheet layer, which changes the agglomeration of pure cerium oxide nanoparticles and also makes the hydrotalcite sheet layer difficult to agglomerate. In addition to improving the catalytic performance of cerium oxide It also produces a synergistic catalytic effect with hydrotalcite, and is a new type of efficient composite catalyst. The cerium oxide-hydrotalcite composite catalyst has excellent catalytic performance and is expected to be used in environmental protection fields such as refractory wastewater treatment and waste gas treatment, with promising commercial prospects. Compared with the prior art, the present invention adopts the double in-situ one-step hydrothermal synthesis method, and has the advantages of simple production process, easy process control, low energy consumption and production cost, etc., and can be industrially produced on a large scale.

Description

Cerium oxide-hydrotalcite composite catalyst, preparation method and application

Technical Field

The invention belongs to the technical field of materials, and relates to a cerium oxide-hydrotalcite composite catalyst, a preparation method and application thereof.

Background

Hydrotalcite (Hydrotalcite) compounds, also called Layered Double Hydroxides (LDHs), are a class of layered structure materials with anionic intercalation. Because of their special layered structure, they exhibit good performance in catalysis, adsorption, separation, ion exchange, and wastewater treatment. In recent years, hydrotalcite compounds have attracted much attention as a novel catalyst carrier due to the particularity of their layered structure, the exchangeability of anions between layers, the controllability of metal elements in layers, and the intrinsic basicity.

CeO₂The rare earth oxide is a cheap and widely-used rare earth oxide, has the forbidden band width of 2.94eV and the light absorption threshold of about 420nm, can be used for catalysts, polishing powder, ultraviolet absorption materials and the like, has a plurality of new properties and uses after nanocrystallization, and has wide application prospects in the aspects of chemical industry and environmental pollution control.

LDHs load CeO₂The composite catalyst has the synergistic effect of chemical catalysis and physical catalysis, and is a novel efficient composite catalyst.

Preparation of Cestrum species (Cestrum species, high brilliant. hydrotalcite compound-cerium oxide catalyst) and performance study of photodegradation of methyl orange [ J]Petrochemical, 2012,41(2):204-209) prepared LDHs-CeO by coprecipitation method₂(LDHs is hydrotalcite compound) catalyst, and the catalyst is used for photocatalytic degradation of methyl orange solution, and the influence of the raw material ratio, the reaction time, the initial content of methyl orange, the pH of the methyl orange solution and the catalyst dosage of the catalyst on the degradation rate of methyl orange is examined; meanwhile, the catalyst is characterized by methods such as FTIR, XRD, SEM, TEM, EDS, TG and the like. The experimental result shows that the LDHs-CeO of n (Mg), n (Al) and n (Ce) is 2: 1: 0.50₂The activity of the catalyst is the highest,the suitable conditions for degrading the methyl orange solution by the catalyst through photocatalysis are as follows: 250mL of methyl orange solution, wherein the initial mass concentration of methyl orange is 40mg/L, the pH value is 5, the reaction time is 80min (standing in the dark for 20min, and the illumination time is 60min), and the dosage of the catalyst is 0.3 g; under the condition, the degradation rate of methyl orange reaches 98.69 percent. The characterization result shows that LDHs-CeO₂The crystal phase is single, the crystal structure is consistent, the crystallinity is good, the crystal belongs to a hexagonal crystal system, the appearance is a regular sheet structure, and the dispersity is good.

Preparation and environmental application of Xifei et al (Xifei, Li Jing, jin Guanping, ceric oxide/calcium aluminium hydrotalcite/active carbon [ J)]Chemical evolution, 2016,35(1): 182-188; preparation of Xifei functional active carbon composite material and water treatment application [ D]Preparing cerium dioxide/calcium aluminum hydrotalcite/active carbon composite material (CeO) by adopting an ultrasonic-assisted coprecipitation method, namely 2016 and 03 of university of combined fertilizer industry₂/CaAl-LDHs/AC). Performing field emission scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis on CeO₂The morphology, composition and structure of the/CaAl-LDHs/AC are characterized. As a result, it was found that: flower-like sheet layered CeO₂the/CaAl-LDHs material is uniformly distributed on the activated carbon. Examine CeO₂The adsorption performance of/CaAl-LDHs/AC on chromium (VI), lead (II), fluorine and malachite green in an aqueous solution. The adsorption process of the pollutants conforms to a quasi-second order kinetic model and a Langmuir isothermal model; at pH 7, 45 ℃ and adsorption time 2h, CeO₂the/CaAl-LDHs/AC can be successfully used for adsorbing and removing chromium (VI), lead (II), fluorine and malachite green, and the maximum adsorption amounts are 83.06mg/g, 131.58mg/g, 61.20mg/g and 420.17mg/g respectively.

Lijing (preparation of Lijing carbon carrier composite material and treatment study of sulfide in aqueous solution [ D ]]Preparation of cerium oxide-nickel aluminum/layered double hydroxide/chelated active carbon composite (CeO) by Urea hydrolysis method using chelated active carbon as carrier₂NiAl-LDHs/MFT/AC). And the structure and the performance of the composite material are characterized by adopting a Fourier infrared spectrum (FT-IR), X-ray crystal diffraction (XRD), a field emission scanning electron microscope (FE-SEM) and an electrochemical method. ResultsShows that: petal-shaped CeO₂the-NiAl-LDHs are uniformly dispersed on the surface of the chelating activated carbon. Examine CeO₂The adsorption behavior of NiAl-LDHs/MFT/AC on sulfides in aqueous solutions. The results show that: the adsorption process is a spontaneous endothermic reaction, and conforms to a quasi-second order kinetic model and a Langmuir adsorption model. The maximum adsorption amount of sulfite ions at room temperature is 483.09mg/g, and the maximum adsorption amount of sulfur ions is 181.15 mg/g. Then, CeO was prepared₂-NiAl-LDHs/MFT/AC and carbon nanotube mixture modified wax-filled graphite electrode (MWCNTs/CeO)₂NiAl-LDHs/MFT/AC/WGE). The electrochemical catalytic oxidation behavior of the electrode on sulfides in water was studied. The results show that: the modified electrode can successfully oxidize sulfite and sulfide ions in water into sulfate radicals. Preparing cerium dioxide-nickel aluminum/layered double hydroxide/graphene oxide composite material (CeO) by using graphene oxide as carrier and adopting urea hydrolysis method₂-NiAl-LDHs/GO). And the structure and the performance of the composite material are characterized by FT-IR, XRD, FE-SEM and electrochemical methods. The results show that: layered CeO₂NiAl-LDHs complexes have formed. Prepared CeO by coating method₂-NiAl-LDHs/GO modified wax-filled graphite electrode, which is used for detecting sulfite and sulfide ions in water. The results show that: SO (SO)₃ ^2-And S^2-The oxidation peak current and the concentration of (2) are respectively 1X 10^-6～13×10^-6mol/L and 1X 10^-6～15×10^-6Within the concentration range of mol/L, the linear growth relationship is good, and the detection limit is respectively 7 multiplied by 10^-8mol/L and 2X 10^-7mol/L(3σ)。

Design synthesis and property study of Wangganskey (Wangganskey. rare earth composite hydrotalcite-based heterogeneous catalyst [ D)]Lanzhou, Lanzhou university, 2019,04) constructs a novel CeO by utilizing a synthesis strategy of a self-sacrifice template₂Catalyst with @ NC/LDH core-shell structure. The catalyst shows excellent OER catalytic activity and stability in alkaline electrolyte. This high performance benefits primarily from the rare earth CeO₂The introduction of the catalyst effectively regulates and controls the electronic state of the catalyst and forms more defect structures. In addition, the surface in-situ growth strategy can also prevent LDH lamella aggregationIncreasing the number of active sites.

Disclosure of Invention

The invention aims to provide a novel high-efficiency cerium oxide-hydrotalcite composite catalyst, which has a simple preparation process and solves the problems of poor catalytic effect, complex preparation process, high cost and the like of the conventional single catalyst.

The invention is realized by the following technical scheme:

a preparation method of a cerium oxide-hydrotalcite composite catalyst comprises the following steps:

(1) a certain amount of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-The molar ratio is (1.5-3):1, uniformly dropwise adding the solution B into the solution A, magnetically stirring, and reacting to obtain a precursor C;

(2) with a quantity of Me (II) (NO)₃)₂·6H₂O、Al(NO₃)₃·9H₂O) preparation of solutions D, Me²⁺With Al³⁺The molar ratio is (1.5-3):1, a certain amount of solution B is taken, and NaOH and NO in the solution B and D are controlled^3-The molar ratio is (1.5-3):1, uniformly dropwise adding the solution B into the solution D, magnetically stirring, and reacting to obtain a precursor E;

(3) pressing the precursor C and the precursor E according to Ce²⁺And Me²⁺Mixing the components according to the molar ratio of (0.1-5), adding the mixture into a hydrothermal reaction kettle, reacting at a certain temperature, cooling, washing with water to be neutral, and drying to obtain the cerium oxide-hydrotalcite composite catalyst.

Preferably, the temperature of the magnetic stirring in the step (1) is 60-80 ℃.

Preferably, the reaction time in step (1) is 0.5-2 h.

Preferably, Me in the step (2) is one of divalent metal elements of Fe, Mg, Zn, Ni, Co, Mn and Cu.

Preferably, the temperature of the magnetic stirring in the step (2) is 60-80 ℃.

Preferably, the reaction time in step (2) is 0.5-2 h.

Preferably, the reaction temperature in step (3) is 120-180 ℃.

Preferably, the reaction time in step (3) is 5-24 h.

The invention also protects the cerium oxide-hydrotalcite composite catalyst prepared by the preparation method.

The invention also protects the application of the cerium oxide-hydrotalcite composite catalyst in the fields of chemical industry and environmental protection.

The invention has the beneficial effects that:

the cerium oxide-hydrotalcite composite catalyst is characterized in that cerium oxide nanoparticles are distributed on hydrotalcite lamella, so that agglomeration of pure cerium oxide nanoparticles is changed, the hydrotalcite lamella is not easy to agglomerate, the cerium oxide catalytic performance is improved, and a synergistic catalytic effect is generated with hydrotalcite, so that the cerium oxide-hydrotalcite composite catalyst is a novel efficient composite catalyst. The cerium oxide-hydrotalcite composite catalyst has excellent catalytic performance, is expected to be used in the environment-friendly fields of treatment of refractory wastewater, treatment of waste gas and the like, and has considerable commercialization prospect. Compared with the prior art, the method adopts a double in-situ one-step hydrothermal synthesis method, has the advantages of simple production process, easy process control, low energy consumption and production cost and the like, and can be used for large-scale industrial production.

Drawings

FIG. 1 is an SEM picture of a sample of example 1;

FIG. 2 is an SEM picture of a sample of example 2;

FIG. 3 is an SEM picture of a sample of example 3;

FIG. 4 is an SEM picture of a sample of example 4;

figure 5 is an XRD pattern of the samples of examples 1-4.

Detailed Description

For a better understanding of the present invention, the present invention will be further described with reference to the following examples and the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting thereof.

Example 1:

(1)0.005ml of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NaOH in the solution B and ANO^3-And (3) uniformly dropwise adding the solution B into the solution A at a molar ratio of 2:1, magnetically stirring at 70 ℃, and reacting for 2 hours to obtain a precursor C.

(2) With 0.005molMg (NO)₃)₂·6H₂O and a certain amount of Al (NO)₃)₃·9H₂O) preparation of solution D, Mg²⁺With Al³⁺Taking a certain amount of solution B with the molar ratio of 2:1, controlling NaOH and NO in the solution B and the solution D^3-And (3) uniformly dropwise adding the solution B into the solution D at a molar ratio of 2:1, magnetically stirring at 70 ℃, and reacting for 2 hours to obtain a precursor E.

(3) And mixing the solution C and the solution E, adding the mixture into a hydrothermal reaction kettle, putting the hydrothermal reaction kettle into a drying oven, reacting for 12 hours at 160 ℃, cooling, washing with water to be neutral, and drying to obtain a cerium oxide-hydrotalcite composite catalyst sample.

Example 2:

(1)0.01mol of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-The molar ratio is 2: and 1, uniformly dropwise adding the solution B into the solution A, magnetically stirring at 70 ℃, and reacting for 2 hours to obtain a precursor C.

(2)0.005molMg(NO₃)₂·6H₂O and a certain amount of Al (NO)₃)₃·9H₂O) preparation of solution D, Mg²⁺With Al³⁺Taking a certain amount of solution B with the molar ratio of 2:1, controlling NaOH and NO in the solution B and the solution D^3-And (3) uniformly dropwise adding the solution B into the solution D at a molar ratio of 2:1, magnetically stirring at 70 ℃, and reacting for 2 hours to obtain a precursor E.

Example 3:

(1)0.015mol of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-The molar ratio is 2:1, the solution B is evenly dripped into the solution A, the solution A is magnetically stirred at the temperature of 70 ℃, and the reaction 2 is carried outh to obtain a precursor C.

Example 4:

(1)0.02mol of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-And (3) uniformly dropwise adding the solution B into the solution A at a molar ratio of 2:1, magnetically stirring at 70 ℃, and reacting for 2 hours to obtain a precursor C.

Example 5:

(1)0.005mol of cerium (Ce (NO) acid₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-And (3) uniformly dropwise adding the solution B into the solution A at a molar ratio of 1.5:1, magnetically stirring at 80 ℃, and reacting for 0.5h to obtain a precursor C.

(2)0.01molMn(NO₃)₂·6H₂O and a certain amount of Al (NO)₃)₃·9H₂O) preparation of solution D, where Mn²⁺With Al³⁺The molar ratio is 1.5:1, a certain amount of solution B is taken, NaOH and NO in the solution B and D are controlled^3-And (3) uniformly dropwise adding the solution B into the solution D at a molar ratio of 1.5:1, magnetically stirring at 80 ℃, and reacting for 0.5h to obtain a precursor E.

(3) And mixing the solution C and the solution E, adding the mixture into a hydrothermal reaction kettle, putting the hydrothermal reaction kettle into a drying oven, reacting for 24 hours at 130 ℃, cooling, washing with water to be neutral, and drying to obtain a cerium oxide-hydrotalcite composite catalyst sample.

Example 6:

(1)0.025mol of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-The molar ratio is 2.5: and 1, uniformly dropwise adding the solution B into the solution A, magnetically stirring at 60 ℃, and reacting for 2 hours to obtain a precursor C.

(2)0.005molNi(NO₃)₂·6H₂O and a certain amount of Al (NO)₃)₃·9H₂O) preparation of solution D, Ni²⁺With Al³⁺The molar ratio is 2.5:1, a certain amount of solution B is taken, NaOH and NO in the solution B and D are controlled^3-And uniformly dripping the solution B into the solution D at a molar ratio of 2.5:1, magnetically stirring at 60 ℃, and reacting for 2 hours to obtain a precursor E.

(3) And mixing the solution C and the solution E, adding the mixture into a hydrothermal reaction kettle, putting the hydrothermal reaction kettle into a drying oven, reacting for 10 hours at 150 ℃, cooling, washing with water to be neutral, and drying to obtain a cerium oxide-hydrotalcite composite catalyst sample.

Example 7:

(1)0.002mol of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-And (3) uniformly dropwise adding the solution B into the solution A at a molar ratio of 3:1, magnetically stirring at 80 ℃, and reacting for 1.5 hours to obtain a precursor C.

(2)0.005molZn(NO₃)₂·6H₂O and a certain amount of Al (NO)₃)₃·9H₂O) preparing a solution D,wherein Zn is²⁺With Al³⁺Taking a certain amount of solution B, controlling NaOH and NO in the solution B and D at a molar ratio of 3:1^3-And (3) uniformly dropwise adding the solution B into the solution D at a molar ratio of 3:1, magnetically stirring at 80 ℃, and reacting for 1.5 hours to obtain a precursor E.

(3) And mixing the solution C and the solution E, adding the mixture into a hydrothermal reaction kettle, putting the hydrothermal reaction kettle into a drying oven, reacting for 6 hours at 170 ℃, cooling, washing with water to be neutral, and drying to obtain a cerium oxide-hydrotalcite composite catalyst sample.

Example 8:

(1)0.0015mol of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-And (3) uniformly dropwise adding the solution B into the solution A at a molar ratio of 2:1, magnetically stirring at 65 ℃, and reacting for 1.5 hours to obtain a precursor C.

(2)0.005molFe(NO₃)₂·6H₂O and a certain amount of Al (NO)₃)₃·9H₂O) preparation of solution D, where Fe²⁺With Al³⁺The molar ratio is 2.5:1, a certain amount of solution B is taken, NaOH and NO in the solution B and D are controlled^3-And (3) uniformly dropwise adding the solution B into the solution D at a molar ratio of 2:1, magnetically stirring at 65 ℃, and reacting for 1.5 hours to obtain a precursor E.

(3) And mixing the solution C and the solution E, adding the mixture into a hydrothermal reaction kettle, putting the hydrothermal reaction kettle into a drying oven, reacting for 24 hours at 120 ℃, cooling, washing with water to be neutral, and drying to obtain a cerium oxide-hydrotalcite composite catalyst sample.

Example 9:

(1)0.001mol of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-And (3) uniformly dropwise adding the solution B into the solution A at a molar ratio of 1.5:1, magnetically stirring at 75 ℃, and reacting for 1h to obtain a precursor C.

(2)0.005molCo(NO₃)₂·6H₂O and a certain amount of Al (NO)₃)₃·9H₂O) preparation of solution D, where Co²⁺With Al³⁺Taking a certain amount of solution B, controlling the solution B and the solution D to dissolve at a molar ratio of 3:1NaOH and NO in liquid^3-And (3) uniformly dropwise adding the solution B into the solution D at a molar ratio of 1.5:1, magnetically stirring at 75 ℃, and reacting for 1h to obtain a precursor E.

(3) And mixing the solution C and the solution E, adding the mixture into a hydrothermal reaction kettle, putting the hydrothermal reaction kettle into a drying oven, reacting for 5 hours at 180 ℃, cooling, washing with water to be neutral, and drying to obtain a cerium oxide-hydrotalcite composite catalyst sample.

Example 10:

(1)0.0005mol of cerium nitrate (Ce (NO)₃)₂·6H₂O) preparing solution A, preparing solution B from a certain amount of NaOH aqueous solution, taking a certain amount of solution B, and controlling NaOH and NO in the solution B and A^3-And (3) uniformly dropwise adding the solution B into the solution A at a molar ratio of 2:1, magnetically stirring at 70 ℃, and reacting for 1.5 hours to obtain a precursor C.

(2)0.005molCu(NO₃)₂·6H₂O and a certain amount of Al (NO)₃)₃·9H₂O) preparation of solution D, in which Cu²⁺With Al³⁺The molar ratio is 2.5:1, a certain amount of solution B is taken, NaOH and NO in the solution B and D are controlled^3-And (3) uniformly dropwise adding the solution B into the solution D at a molar ratio of 2:1, magnetically stirring at 70 ℃, and reacting for 1.5 hours to obtain a precursor E.

(3) And mixing the solution C and the solution E, adding the mixture into a hydrothermal reaction kettle, putting the hydrothermal reaction kettle into a drying oven, reacting for 20 hours at 140 ℃, cooling, washing with water to be neutral, and drying to obtain a cerium oxide-hydrotalcite composite catalyst sample.

The samples of examples 1-4 were tested for photocatalytic performance by the following methods:

(1) preparing a salt-based fuchsin solution with the concentration of 8.0730 mg/L;

(2) weighing 0.0180g of the sample of example 1-4 into a 100ml conical flask;

(3) transferring 18ml of the salt base fuchsin solution prepared in the step (1) into the conical flask in the step (2);

(4) performing adsorption-desorption balance, namely performing magnetic stirring in a water bath for 2 hours under the constant temperature (25 ℃) and light-proof condition, sucking 9ml of suspension into a 10ml centrifuge tube, marking as ①, and placing in the light-proof condition;

(5) performing photocatalysis, namely performing photodegradation on the residual suspension in the conical flask in the step (3) for 2 hours under the condition of a 365nm ultraviolet lamp, taking out the conical flask, and transferring the residual suspension into a 10ml centrifugal tube, wherein the mark is ②;

(6) centrifuging for 20min at 10000r/min in a high-speed refrigerated centrifuge, taking supernatant into a prepared 10ml centrifuge tube with a sharp end, and marking as (I);

(7) measuring absorbance (A), namely setting the wavelength of an ultraviolet visible spectrophotometer to be 546nm, using distilled water as a standard test solution, and measuring the absorbance of supernatant liquid I and II, wherein the absorbance is marked as A01, A02 and A03, and At1, At2 and At 3;

(8) calculating the concentration of supernatant liquid (C0 and C1), wherein [ A ═ epsilon bc: epsilon 9.5107L/g.cm is absorption coefficient (L/g.cm), b is cuvette thickness (cm), and C is solution concentration (g/L) ];

(9) degradation rate of basic fuchsin solution:

(10) as shown in Table 1, the photodegradation rates of the basic fuchsin solutions of examples 1-4 were all above 90%.

TABLE 1 EXAMPLES 1-4 sample salt-based magenta solution photodegradation ratio List

	Example 1	Example 2	Example 3	Example 4
					Degradation Rate (%)	92.6	90.8	93.2	91.3

The samples of examples 1-4 were examined by SEM and XRD, respectively.

Fig. 1 to 4 are SEM pictures of samples of examples 1 to 4, respectively, and it can be seen from fig. 1 to 4 that hexagonal and other shaped lamellae of the ceria-hydrotalcite composite catalyst sample prepared by the dual in-situ hydrothermal one-step synthesis method are hydrotalcite, the white point of the surface of the lamellae is ceria, and the ceria is distributed on the surface of the lamellae of the hydrotalcite.

FIG. 5 is an XRD pattern of the samples of examples 1-4 with the characteristic diffraction peaks of cerium oxide marked by inverted triangles. From fig. 5 and the standard XRD card of magnesium aluminum hydrotalcite, the characteristic diffraction peaks of (003), (006), (009), (015), (110) and (113) of magnesium aluminum hydrotalcite are all found, and are obvious and sharp, indicating that the cerium oxide-hydrotalcite composite catalyst samples synthesized in examples 1-4 all have the structure of magnesium aluminum hydrotalcite and good crystallinity. The sample still had a diffraction peak for ceria, indicating that the sample still had the magnetic substrate ceria, as compared to the XRD card for ceria.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. a preparation method of cerium oxide-hydrotalcite composite catalyst, is characterized in that, comprises the following steps:

(1) A certain amount of cerium nitrate (Ce(NO ₃ ) ₂ 6H ₂ O) was prepared to prepare solution A, a certain amount of NaOH aqueous solution was prepared to prepare solution B, a certain amount of solution B was taken, and the ^3- molar ratio of NaOH and NO in solutions B and A was controlled For (1.5-3): 1, evenly add solution B dropwise to solution A, stir magnetically, and react to obtain precursor C;

(2) Prepare solution D with a certain amount of Me(II)(NO ₃ ) ₂ ·6H ₂ O, Al(NO ₃ ) ₃ ·9H ₂ O), and the molar ratio of Me ²⁺ to Al ³⁺ is (1.5-3) : 1, take a certain amount of solution B, control the molar ratio of NaOH to NO ^3- in solutions B and D to be (1.5-3): 1, evenly add solution B dropwise to solution D, stir magnetically, and react to obtain precursor E ;

(3) Mix the precursor C and the precursor E into the hydrothermal reactor according to the molar ratio of Ce ²⁺ and Me ²⁺ (0.1-5), react at a certain temperature, wash with water after cooling to neutrality, and dry to obtain oxidation Cerium-hydrotalcite composite catalyst.

2 . The method for preparing a ceria-hydrotalcite composite catalyst according to claim 1 , wherein the magnetic stirring temperature in step (1) is 60-80° C. 3 .

3 . The preparation method of a ceria-hydrotalcite composite catalyst according to claim 1 , wherein the reaction time of step (1) is 0.5-2 h. 4 .

4 . The preparation method of a ceria-hydrotalcite composite catalyst according to claim 1 , wherein the Me in step (2) is two of Fe, Mg, Zn, Ni, Co, Mn and Cu. 5 . One of the valence metal elements.

5 . The method for preparing a ceria-hydrotalcite composite catalyst according to claim 1 , wherein the magnetic stirring temperature in step (2) is 60-80° C. 6 .

6 . The preparation method of a ceria-hydrotalcite composite catalyst according to claim 1 , wherein the reaction time of step (2) is 0.5-2 h. 7 .

7 . The method for preparing a ceria-hydrotalcite composite catalyst according to claim 1 , wherein the reaction temperature in step (3) is 120-180° C. 8 .

8 . The method for preparing a ceria-hydrotalcite composite catalyst according to claim 1 , wherein the reaction time in step (3) is 5-24 h. 9 .

9. A ceria-hydrotalcite composite catalyst prepared by the preparation method according to any one of claims 1-8.

10. The application of the cerium oxide-hydrotalcite composite catalyst of claim 9 in chemical industry and environmental protection field.