CATALYST FOR SYNERGISTIC REMOVAL OF NITROGEN OXIDES AND CO AS WELL AS PREPARATION METHOD AND USE THEREOF

Abstract

Disclosed are a catalyst for synergistic removal of nitrogen oxides (NO.sub.x) and CO as well as a preparation method and use thereof. The preparation method comprises: performing vibratory ball milling, washing, drying and calcining on aluminum isopropoxide and/or titanium isopropoxide, chlorides of five or more different metal elements and P123 and/or polyethylene glycol (PEG), stirring the obtained high-entropy oxide inner core and a gel of H.sub.3PO.sub.4 and Ce(NO.sub.3).sub.3, and then performing vibratory ball milling, washing, drying and calcining to obtain an high-entropy oxide loaded with CePO.sub.4 seeds; and preparing, by using ammonia water, a clear solution containing pyrophosphate and Ce(NO.sub.3).sub.3 in equal stoichiometric ratios, then adding the high-entropy oxide loaded with the CePO.sub.4 seeds and urea and/or tetrapropylammonium hydroxide (TPAH) to form a slurry, and, after hydrothermal reaction, washing, drying and calcining a solid to obtain the catalyst.

Claims

1. A catalyst for synergistic removal of nitrogen oxides (NO.sub.x) and carbon monoxide (CO), having a core-shell structure with aluminum oxide and/or titanium oxide loaded with a high-entropy oxide as a core and CePO.sub.4 as a shell, wherein the core is also loaded with a layer of CePO.sub.4; the high-entropy oxide being an oxide composed of a Cu element and at least four metal elements selected from Co, Zn, Mn, Mg, Ni and Fe.

2. The catalyst according to claim 1, wherein all metal elements in the high-entropy oxide are in an equimolar ratio.

3. The catalyst according to claim 2, wherein a molar ratio of the Cu element to CePO.sub.4 in the high-entropy oxide is 1:2-10.

4. A preparation method of the catalyst according to claim 1, comprising the steps: (1) performing vibratory ball milling, washing, drying and calcining by using aluminum isopropoxide and/or titanium isopropoxide and chlorides of five or more different metal elements as a precursor and adding P123 and/or polyethylene glycol (PEG) as a template agent to obtain a high-entropy oxide inner core; (2) adjusting the pH of a mixed solution containing H.sub.3PO.sub.4 and Ce(NO.sub.3).sub.3 in a molar ratio of 1:1 to 9-11 using ammonia water, stirring sufficiently to form a gel, and then sufficiently stirring the high-entropy oxide inner core obtained in step (1) with the gel, followed by vibratory ball milling, washing, drying and calcining, so as to obtain a high-entropy oxide loaded with CePO seeds; and (3) providing a mixed solution containing pyrophosphate and Ce(NO.sub.3).sub.3 in equal stoichiometric ratios, adding ammonia water into the above mixed solution to obtain a clear solution, then adding the high-entropy oxide loaded with the CePO.sub.4 seeds obtained in step (2) and urea and/or tetrapropylammonium hydroxide (TPAH) to form a slurry, and then after hydrothermal reaction, washing, drying and calcining a solid so as to obtain the catalyst for synergistic removal of NO.sub.x and CO.

5. The preparation method according to claim 4, wherein in step (1): a molar ratio of the aluminum isopropoxide and/or titanium isopropoxide to the chlorides is 2:1-10; the chlorides are all divalent metal chlorides and must comprise CuCl.sub.2; a mass ratio of the template agent to the precursor is 0.1-1:1; and the temperature of the calcining is 380-420 C., and the time of the calcining is 3-5 h.

6. The preparation method according to claim 4, wherein in step (2): the temperature of the calcining is 380-420 C., and the time of the calcining is 3-5 h; and the mass percentage of the CePO.sub.4 seeds in the high-entropy oxide loaded with CePO.sub.4 seeds is 5%- 20%.

7. The preparation method according to claim 4, wherein in step (3): a molar ratio of the urea and/or TPAH to Ce(NO.sub.3).sub.3 is 1-10:1; the temperature of the hydrothermal reaction is 120-200 C., and the time of the hydrothermal reaction is 8-24 h; and the temperature of the calcining is 380-420 C., and the time of the calcining is 3-5 h.

8. Use of the catalyst according to claim 1 in selective catalytic reduction and synergistic removal of NO.sub.x and CO.

Description

EXAMPLE 1

Preparation of a Catalyst

[0034] (1) Copper chloride, nickel chloride, ferrous chloride, cobalt chloride and magnesium chloride in an equimolar ratio were mixed with aluminum isopropoxide and PEG-4000, and the above obtained mixture was subjected to high-speed vibratory ball milling for 120 min under the condition of 30 Hz, the product after vibratory ball milling was washed with ethanol and underwent vacuum drying at 40 C., and then the product after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide inner core. The addition amount of each component was as follows: a total molar amount of metal chlorides: a molar amount of aluminum isopropoxide=5:3.33; and 0.4 g of PEG-4000 was added into 5 mmol of metal chlorides. [0035] (2) The pH of a mixed solution of phosphoric acid and cerium nitrate hexahydrate in a molar ratio of 1:1 was adjusted to 10 using strong ammonia water, the above mixed solution was sufficiently stirred to form a gel, then the inner core prepared in step (1) was added into the gel to be sufficiently stirred, wherein, the mass percentage of CePO.sub.4 was 5%, the sample after stirring was then subjected to high-speed vibratory ball milling again, the sample after ball milling underwent vacuum drying at 40 C. after standing for a period of time, and subsequently the sample after vacuum drying was calcined at 400 C. for 4 h to form a high-entropy oxide loaded with CePO.sub.4 seeds. [0036] (3) An equal stoichiometric amount of cerium nitrate solution was dropwise added into a pyrophosphoric acid solution, then the pH of the above solution was adjusted to 4 using ammonia water, the high-entropy oxide loaded with the CePO.sub.4 seeds prepared in step (2) and urea were added, wherein 2 mol of urea was added in per mole of cerium nitrate, then the mixture was subjected to hydrothermal reaction for 12 h at 180 C. after being sufficiently stirred for 30 min, the obtained sample was subjected to washing and vacuum drying, and then the sample after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide@CePO.sub.4 catalyst. A molar ratio of a Cu element to CePO.sub.4 in the high-entropy oxide was 1:10.

Catalyst Activity Test

[0037] An activity experiment was carried out on a fixed bed reactor, the loading volume of the catalyst was 2.3 mL, and the granularity of the catalyst was 40-60 meshes. The volume concentrations of initial gases were as follows: NO=NH.sub.3=600 ppm, CO=1200 ppm, O.sub.2=5 vol %, H.sub.2O=5 vol %, N.sub.2 is a balance gas, and a gas firing hourly space velocity (GHSV)=40,000 h.sup.1. When the reaction temperature was 280 C., the NO conversion rate was 99.6%, the N.sub.2 selectivity was 99.8%, and the CO conversion rate was 64.3%; and when the reaction temperature was 380 C., the NO conversion rate was 99.3%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 100%.

EXAMPLE 2

Preparation of a Catalyst

[0038] (1) Copper chloride, nickel chloride, ferrous chloride, cobalt chloride and magnesium chloride in an equimolar ratio were mixed with aluminum isopropoxide and PEG-4000, and the above obtained mixture was subjected to high-speed vibratory ball milling for 120 min under the condition of 30 Hz, the product after vibratory ball milling was washed with ethanol and underwent vacuum drying at 40 C., and then the product after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide inner core. The addition amount of each component was as follows: a total molar amount of metal chlorides: a molar amount of aluminum isopropoxide=5:3.33; and 0.4 g of PEG-4000 was added into 5 mmol of metal chlorides. [0039] (2) The pH of a mixed solution of phosphoric acid and cerium nitrate hexahydrate in a molar ratio of 1:1 was adjusted to 10 using strong ammonia water, the above mixed solution was sufficiently stirred to form a gel, then the inner core prepared in step (1) was added into the gel to be sufficiently stirred, wherein, the mass percentage of CePO.sub.4 was 5%, the sample after stirring was then subjected to high-speed vibratory ball milling again, the sample after ball milling underwent vacuum drying at 40 C. after standing for a period of time, and subsequently the sample after vacuum drying was calcined at 400 C. for 4 h to form a high-entropy oxide loaded with CePO.sub.4 seeds. [0040] (3) An equal stoichiometric amount of cerium nitrate solution was dropwise added into a pyrophosphoric acid solution, then the pH of the above solution was adjusted to 4 using ammonia water, the high-entropy oxide loaded with the CePO.sub.4 seeds prepared in step (2) and urea were added, wherein 2 mol of urea was added in per mole of cerium nitrate, then the mixture was subjected to hydrothermal reaction for 12 h at 180 C. after being sufficiently stirred for 30 min, the obtained sample was subjected to washing and vacuum drying, and then the sample after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide@CePO.sub.4 catalyst. A molar ratio of a Cu element to CePO.sub.4 in the high-entropy oxide was 1:5.

Catalyst Activity Test

[0041] An activity experiment was carried out on a fixed bed reactor, the loading volume of the catalyst was 2.3 mL, and the granularity of the catalyst was 40-60 meshes. The volume concentrations of initial gases were as follows: NO=NH.sub.3=600 ppm, CO=1200 ppm, O.sub.2=5 vol %, H.sub.2O=5 vol %, N.sub.2 is a balance gas, and GHSV=40,000 h.sup.1. When the reaction temperature was 280 C., the NO conversion rate was 99.8%, the N.sub.2 selectivity was 100%, and the CO conversion rate was 91.3%; and when the reaction temperature was 380 C., the NO conversion rate was 98.7%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 99.7%.

EXAMPLE 3

Preparation of a Catalyst

[0042] (1) Copper chloride, nickel chloride, manganese chloride, cobalt chloride and zinc chloride in an equimolar ratio were mixed with aluminum isopropoxide and PEG-4000, and the above obtained mixture was subjected to high-speed vibratory ball milling for 120 min under the condition of 30 Hz, the product after vibratory ball milling was washed with ethanol and underwent vacuum drying at 40 C., and then the product after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide inner core. The addition amount of each component was as follows: a total molar amount of metal chlorides: a molar amount of aluminum isopropoxide=5:3.33; and 0.4 g of PEG-4000 was added into 5 mmol of metal chlorides. [0043] (2) The pH of a mixed solution of phosphoric acid and cerium nitrate hexahydrate in a molar ratio of 1:1 was adjusted to 10 using strong ammonia water, the above mixed solution was sufficiently stirred to form a gel, then the inner core prepared in step (1) was added into the gel to be sufficiently stirred, wherein, the mass percentage of CePO.sub.4 was 5%, the sample after stirring was then subjected to high-speed vibratory ball milling again, the sample after ball milling underwent vacuum drying at 40 C. after standing for a period of time, and subsequently the sample after vacuum drying was calcined at 400 C. for 4 h to form a high-entropy oxide loaded with CePO.sub.4 seeds. [0044] (3) An equal stoichiometric amount of cerium nitrate solution was dropwise added into a pyrophosphoric acid solution, then the pH of the above solution was adjusted to 4 using ammonia water, the high-entropy oxide loaded with the CePO.sub.4 seeds prepared in step (2) and urea were added, wherein 2 mol of urea was added in per mole of cerium nitrate, then the mixture was subjected to hydrothermal reaction for 12 h at 180 C. after being sufficiently stirred for 30 min, the obtained sample was subjected to washing and vacuum drying, and then the sample after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide@CePO.sub.4 catalyst. A molar ratio of a Cu element to CePO.sub.4 in the high-entropy oxide was 1:5.

Catalyst Activity Test

[0045] An activity experiment was carried out on a fixed bed reactor, the loading volume of the catalyst was 2.3 mL, and the granularity of the catalyst was 40-60 meshes. The volume concentrations of initial gases were as follows: NO=NH.sub.3=600 ppm, CO=1200 ppm, O.sub.2=5 vol %, H.sub.2O=5 vol %, N.sub.2 is a balance gas, and GHSV=40,000 h.sup.1. When the reaction temperature was 280 C., the NO conversion rate was 99.7%, the N.sub.2 selectivity was 99.9%, and the CO conversion rate was 92.8%; and when the reaction temperature was 380 C., the NO conversion rate was 97.2%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 98.4%.

EXAMPLE 4

Preparation of a Catalyst

[0046] (1) Copper chloride, nickel chloride, ferrous chloride, cobalt chloride and zinc chloride in an equimolar ratio were mixed with aluminum isopropoxide and PEG-4000, and the above obtained mixture was subjected to high-speed vibratory ball milling for 120 min under the condition of 30 Hz, the product after vibratory ball milling was washed with ethanol and underwent vacuum drying at 40 C., and then the product after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide inner core. The addition amount of each component was as follows: a total molar amount of metal chlorides: a molar amount of aluminum isopropoxide=5:3.33; and 0.4 g of PEG-4000 was added into 5 mmol of metal chlorides. [0047] (2) The pH of a mixed solution of phosphoric acid and cerium nitrate hexahydrate in a molar ratio of 1:1 was adjusted to 10 using strong ammonia water, the above mixed solution was sufficiently stirred to form a gel, then the inner core prepared in step (1) was added into the gel to be sufficiently stirred, wherein, the mass percentage of CePO.sub.4 was 5%, the sample after stirring was then subjected to high-speed vibratory ball milling again, the sample after ball milling underwent vacuum drying at 40 C. after standing for a period of time, and subsequently the sample after vacuum drying was calcined at 400 C. for 4 h to form a high-entropy oxide loaded with CePO.sub.4 seeds. [0048] (3) An equal stoichiometric amount of cerium nitrate solution was dropwise added into a pyrophosphoric acid solution, then the pH of the above solution was adjusted to 4 using ammonia water, the high-entropy oxide loaded with the CePO.sub.4 seeds prepared in step (2) and urea were added, wherein 2 mol of urea was added in per mole of cerium nitrate, then the mixture was subjected to hydrothermal reaction for 12 h at 180 C. after being sufficiently stirred for 30 min, the obtained sample was subjected to washing and vacuum drying, and then the sample after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide@CePO.sub.4 catalyst. A molar ratio of a Cu element to CePO.sub.4 in the high-entropy oxide was 1:5.

Catalyst Activity Test

[0049] An activity experiment was carried out on a fixed bed reactor, the loading volume of the catalyst was 2.3 mL, and the granularity of the catalyst was 40-60 meshes. The volume concentrations of initial gases were as follows: NO=NH.sub.3=600 ppm, CO=1200 ppm, O.sub.2=5 vol %, H.sub.2O=5 vol %, N.sub.2 is a balance gas, and GHSV=40,000 h.sup.1. When the reaction temperature was 280 C., the NO conversion rate was 99.6%, the N.sub.2 selectivity was 99.9%, and the CO conversion rate was 92.1%; and when the reaction temperature was 380 C., the NO conversion rate was 98.2%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 98.8%.

EXAMPLE 5

Preparation of a Catalyst

[0050] (1) Copper chloride, nickel chloride, manganese chloride, cobalt chloride and ferrous chloride in an equimolar ratio were mixed with aluminum isopropoxide and PEG-4000, and the above obtained mixture was subjected to high-speed vibratory ball milling for 120 min under the condition of 30 Hz, the product after vibratory ball milling was washed with ethanol and underwent vacuum drying at 40 C., and then the product after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide inner core. The addition amount of each component was as follows: a total molar amount of metal chlorides: a molar amount of aluminum isopropoxide=5:3.33; and 0.4 g of PEG-4000 was added into 5 mmol of metal chlorides. [0051] (2) The pH of a mixed solution of phosphoric acid and cerium nitrate hexahydrate in a molar ratio of 1:1 was adjusted to 10 using strong ammonia water, the above mixed solution was sufficiently stirred to form a gel, then the inner core prepared in step (1) was added into the gel to be sufficiently stirred, wherein, the mass percentage of CePO.sub.4 was 5%, the sample after stirring was then subjected to high-speed vibratory ball milling again, the sample after ball milling underwent vacuum drying at 40 C. after standing for a period of time, and subsequently the sample after vacuum drying was calcined at 400 C. for 4 h to form a high-entropy oxide loaded with CePO.sub.4 seeds. [0052] (3) An equal stoichiometric amount of cerium nitrate solution was dropwise added into a pyrophosphoric acid solution, then the pH of the above solution was adjusted to 4 using ammonia water, the high-entropy oxide loaded with the CePO.sub.4 seeds prepared in step (2) and urea were added, wherein 2 mol of urea was added in per mole of cerium nitrate, then the mixture was subjected to hydrothermal reaction for 12 h at 180 C. after being sufficiently stirred for 30 min, the obtained sample was subjected to washing and vacuum drying, and then the sample after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide@CePO.sub.4 catalyst. A molar ratio of a Cu element to CePO.sub.4 in the high-entropy oxide was 1:5.

Catalyst Activity Test

[0053] An activity experiment was carried out on a fixed bed reactor, the loading volume of the catalyst was 2.3 mL, and the granularity of the catalyst was 40-60 meshes. The volume concentrations of initial gases were as follows: NO=NH.sub.3=600 ppm, CO=1200 ppm, O.sub.2=5 vol %, H.sub.2O=5 vol %, N.sub.2 is a balance gas, and GHSV=40,000 h.sup.1. When the reaction temperature was 280 C., the NO conversion rate was 99.8%, the N.sub.2 selectivity was 100%, and the CO conversion rate was 92.6%; and when the reaction temperature was 380 C., the NO conversion rate was 98%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 98.5%.

EXAMPLE 6

Preparation of a Catalyst

[0054] (1) Copper chloride, nickel chloride, manganese chloride, cobalt chloride, ferrous chloride and magnesium chloride in an equimolar ratio were mixed with aluminum isopropoxide and PEG-4000, and the above obtained mixture was subjected to high-speed vibratory ball milling for 120 min under the condition of 30 Hz, the product after vibratory ball milling was washed with ethanol and underwent vacuum drying at 40 C., and then the product after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide inner core. The addition amount of each component was as follows: a total molar amount of metal chlorides: a molar amount of aluminum isopropoxide=5:3.33; and 0.4 g of PEG-4000 was added into 5 mmol of metal chlorides. [0055] (2) The pH of a mixed solution of phosphoric acid and cerium nitrate hexahydrate in a molar ratio of 1:1 was adjusted to 10 using strong ammonia water, the above mixed solution was sufficiently stirred to form a gel, then the inner core prepared in step (1) was added into the gel to be sufficiently stirred, wherein, the mass percentage of CePO.sub.4 was 5%, the sample after stirring was then subjected to high-speed vibratory ball milling again, the sample after ball milling underwent vacuum drying at 40 C. after standing for a period of time, and subsequently the sample after vacuum drying was calcined at 400 C. for 4 h to form a high-entropy oxide loaded with CePO.sub.4 seeds. [0056] (3) An equal stoichiometric amount of cerium nitrate solution was dropwise added into a pyrophosphoric acid solution, then the pH of the above solution was adjusted to 4 using ammonia water, the high-entropy oxide loaded with the CePO.sub.4 seeds prepared in step (2) and urea were added, wherein 2 mol of urea was added in per mole of cerium nitrate, then the mixture was subjected to hydrothermal reaction for 12 h at 180 C. after being sufficiently stirred for 30 min, the obtained sample was subjected to washing and vacuum drying, and then the sample after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide@CePO.sub.4 catalyst. A molar ratio of a Cu element to CePO.sub.4 in the high-entropy oxide was 1:5.

Catalyst Activity Test

[0057] An activity experiment was carried out on a fixed bed reactor, the loading volume of the catalyst was 2.3 mL, and the granularity of the catalyst was 40-60 meshes. The volume concentrations of initial gases were as follows: NO=NH.sub.3=600 ppm, CO=1200 ppm, O.sub.2=5 vol %, H.sub.2O=5 vol %, N.sub.2 is a balance gas, and GHSV=40,000 h.sup.1. When the reaction temperature was 280 C., the NO conversion rate was 99.7%, the N.sub.2 selectivity was 100%, and the CO conversion rate was 94.2%; and when the reaction temperature was 380 C., the NO conversion rate was 95.5%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 97.2%.

EXAMPLE 7

Preparation of a Catalyst

[0058] (1) Copper chloride, nickel chloride, magnesium chloride, cobalt chloride, zinc chloride and ferrous chloride in an equimolar ratio were mixed with aluminum isopropoxide and PEG-4000, and the above obtained mixture was subjected to high-speed vibratory ball milling for 120 min under the condition of 30 Hz, the product after vibratory ball milling was washed with ethanol and underwent vacuum drying at 40 C., and then the product after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide inner core. The addition amount of each component was as follows: a total molar amount of metal chlorides: a molar amount of aluminum isopropoxide-5:3.33; and 0.4 g of PEG-4000 was added into 5 mmol of metal chlorides. [0059] (2) The pH of a mixed solution of phosphoric acid and cerium nitrate hexahydrate in a molar ratio of 1:1 was adjusted to 10 using strong ammonia water, the above mixed solution was sufficiently stirred to form a gel, then the inner core prepared in step (1) was added into the gel to be sufficiently stirred, wherein, the mass percentage of CePO.sub.4 was 5%, the sample after stirring was then subjected to high-speed vibratory ball milling again, the sample after ball milling underwent vacuum drying at 40 C. after standing for a period of time, and subsequently the sample after vacuum drying was calcined at 400 C. for 4 h to form a high-entropy oxide loaded with CePO.sub.4 seeds. [0060] (3) An equal stoichiometric amount of cerium nitrate solution was dropwise added into a pyrophosphoric acid solution, then the pH of the above solution was adjusted to 4 using ammonia water, the high-entropy oxide loaded with the CePO.sub.4 seeds prepared in step (2) and urea were added, wherein 2 mol of urea was added in per mole of cerium nitrate, then the mixture was subjected to hydrothermal reaction for 12 h at 180 C. after being sufficiently stirred for 30 min, the obtained sample was subjected to washing and vacuum drying, and then the sample after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide@CePO.sub.4 catalyst. A molar ratio of a Cu element to CePO.sub.4 in the high-entropy oxide was 1:5.

Catalyst Activity Test

[0061] An activity experiment was carried out on a fixed bed reactor, the loading volume of the catalyst was 2.3 mL, and the granularity of the catalyst was 40-60 meshes. The volume concentrations of initial gases were as follows: NO=NH.sub.3=600 ppm, CO=1200 ppm, O.sub.2=5 vol %, H.sub.2O=5 vol %, N.sub.2 is a balance gas, and GHSV=40,000 h.sup.1. When the reaction temperature was 280 C., the NO conversion rate was 99.5%, the N.sub.2 selectivity was 99.8%, and the CO conversion rate was 94.3%; and when the reaction temperature was 380 C., the NO conversion rate was 95.4%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 96.7%.

EXAMPLE 8

Preparation of a Catalyst

[0062] (1) Copper chloride, nickel chloride, manganese chloride, cobalt chloride, zinc chloride, ferrous chloride and magnesium chloride in an equimolar ratio were mixed with aluminum isopropoxide and PEG-4000, and the above obtained mixture was subjected to high-speed vibratory ball milling for 120 min under the condition of 30 Hz, the product after vibratory ball milling was washed with ethanol and underwent vacuum drying at 40 C., and then the product after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide inner core. The addition amount of each component was as follows: a total molar amount of metal chlorides: a molar amount of aluminum isopropoxide=5:3.33; and 0.4 g of PEG-4000 was added into 5 mmol of metal chlorides. [0063] (2) The pH of a mixed solution of phosphoric acid and cerium nitrate hexahydrate in a molar ratio of 1:1 was adjusted to 10 using strong ammonia water, the above mixed solution was sufficiently stirred to form a gel, then the inner core prepared in step (1) was added into the gel to be sufficiently stirred, wherein, the mass percentage of CePO.sub.4 was 5%, the sample after stirring was then subjected to high-speed vibratory ball milling again, the sample after ball milling underwent vacuum drying at 40 C. after standing for a period of time, and subsequently the sample after vacuum drying was calcined at 400 C. for 4 h to form a high-entropy oxide loaded with CePO.sub.4 seeds. [0064] (3) An equal stoichiometric amount of cerium nitrate solution was dropwise added into a pyrophosphoric acid solution, then the pH of the above solution was adjusted to 4 using ammonia water, the high-entropy oxide loaded with the CePO.sub.4 seeds prepared in step (2) and urea were added, wherein 2 mol of urea was added in per mole of cerium nitrate, then the mixture was subjected to hydrothermal reaction for 12 h at 180 C. after being sufficiently stirred for 30 min, the obtained sample was subjected to washing and vacuum drying, and then the sample after vacuum drying was calcined for 4 h at 400 C. to obtain a high-entropy oxide@CePO.sub.4 catalyst. A molar ratio of a Cu element to CePO.sub.4 in the high-entropy oxide was 1:5.

Catalyst Activity Test

[0065] An activity experiment was carried out on a fixed bed reactor, the loading volume of the catalyst was 2.3 mL, and the granularity of the catalyst was40-60 meshes. The volume concentrations of initial gases were as follows: NO=NH.sub.3=600 ppm, CO=1200 ppm, O.sub.2=5 vol %, H.sub.2O=5 vol %, SO.sub.2=1200 ppm (when in use), N.sub.2 is a balance gas, and GHSV=40,000 h.sup.1. When the reaction temperature was 280 C., the NO conversion rate was 99.9%, the N.sub.2 selectivity was 100%, and the CO conversion rate was 95.6%; and when the reaction temperature was 380 C., the NO conversion rate was 94.3%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 96.4%. After 100 ppm SO.sub.2 was introduced into the reaction gases, at 280 C., the NO conversion rate was 96.2%, the N.sub.2 selectivity was 98.6%, and the CO conversion rate was 79.3%; and at 380 C., the NO conversion rate was 100%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 100%.

Comparative Example 1

Preparation of a Catalyst

[0066] A high-entropy oxide inner core was prepared based on the method in example 8 and CePO.sub.4 was prepared by using a hydrothermal method. Then, the high-entropy oxide inner core and CePO.sub.4 were subjected to dry blending so as not to form a core-shell structure of the present disclosure. A molar ratio of a Cu element to CePO.sub.4 in the high-entropy oxide was 1:5.

Catalyst Activity Test

[0067] The conditions for the catalyst activity test were the same as those in example 8. When the reaction temperature was 280 C., the NO conversion rate was 99.8%, the N.sub.2 selectivity was 100%, and the CO conversion rate was 96%; and when the reaction temperature was 380 C., the NO conversion rate was 76.4%, the CO conversion rate was 100%, and the N.sub.2 selectivity was 80.2%. After 100 ppm SO.sub.2 was introduced into the reaction gases, at 280 C., the NO conversion rate was 96.1%, the N.sub.2 selectivity was 99.8%, and the CO conversion rate was 61.4%; and at 380 C., the NO conversion rate was 100%, the CO conversion rate was 91.5%, and the N.sub.2 selectivity was 100%.

[0068] By comparing comparative example 1 with example 8, it is found that the core-shell structure of the present disclosure has the following two advantages that 1, high NO conversion rate at the high temperature, and meanwhile the CO conversion rate at the low temperature can also be maintained; and 2, good sulfur resisting effect on CO oxidation and high oxidation rate.

[0069] In addition, it should be understood that after reading the contents of the present disclosure as described above, those skilled in the art can make various changes or modifications, and these equivalent forms similarly fall within the scope as defined in claims appended in the present disclosure.