Catalyst for catalytic reduction of industrial flue gas SO.SUB.2 .with CO to prepare sulfur, method for preparing same and use thereof

Abstract

The present invention provides a catalyst for catalytic reduction of an industrial flue gas SO.sub.2 with CO to prepare sulfur, a method for preparing the same and use thereof. A CeO.sub.2 nanocarrier is prepared by using a hydrothermal method, La and Y are loaded as active components, pre-sulfurization is conducted with 6% of SO.sub.2 and 3% of CO, and finally, the catalyst is prepared. The catalyst has high reactivity and sulfur selectivity and strong stability. The by-product sulfur generated by the reaction is recovered with a solvent CS.sub.2, and the solvent CS.sub.2 is recovered by using a distillation process. The preparation method is low in cost, causes no secondary pollution and is high in sulfur recovery rate. The problem of low sulfur production in China at present is solved.

Claims

1. A method for preparing a catalyst for catalytic reduction of an industrial flue gas SO.sub.2 with CO, comprising the following steps: a) respectively dissolving Ce(NO.sub.3).sub.3.Math.6H.sub.2O and NaOH in water to obtain a Ce(NO.sub.3).sub.3.Math.6H.sub.2O aqueous solution and a NaOH aqueous solution, and slowly adding the NaOH aqueous solution dropwise into the Ce(NO.sub.3).sub.3.Math.6H.sub.2O aqueous solution for uniform mixing to obtain a mixed solution 1; b) dissolving cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfonate (SDS) in water to obtain a solution, slowly adding the solution into the mixed solution 1 for stirring for 12-15 h, and conducting a hydrothermal reaction at a temperature of 100-110? C. for 24-26 h; c) cooling a reactant obtained after the hydrothermal reaction in step b) to room temperature, filtering the cooled reactant to collect a white precipitate, and sequentially washing, drying and calcining the white precipitate to obtain a CeO.sub.2 nanorod; d) dissolving La(NO.sub.3).sub.3.Math.6H.sub.2O and Y(NO.sub.3).sub.3.Math.6H.sub.2O in water to obtain a mixed solution 2, and adjusting a pH of the mixed solution 2 to 12; adding the CeO.sub.2 nanorod obtained in step c) into the mixed solution 2, placing the mixed solution 2 on a magnetic stirrer for stirring at a constant speed at 30-40? C. for about 4-6 h, heating the mixed solution to 80-90? C., and continuously stirring the mixed solution until the solution is neutral to obtain a catalyst; and drying the catalyst, and calcining the dried catalyst in an air atmosphere in a muffle furnace at 500-600? C. for 4-6 h to obtain a La-Y/CeO.sub.2 catalyst; and e) pulverizing and sieving the La-Y/CeO.sub.2 catalyst, placing particles with a particle size of 60-80 mesh in a quartz tube, and placing the quartz tube in an electric tube furnace; and then conducting sulfurization at 550-600? C. at a heating rate of 5-15? C./min in a mixed gas comprising 1-10% of CO, 1-10% of SO.sub.2 and the balance of N.sub.2 by volume at an air speed of 5,000-8,000 h.sup.?1 for 1-4 h to obtain a target product sulfurized catalyst.

2. The method according to claim 1, wherein, in step a), a mass ratio of the Ce(NO.sub.3).sub.3.Math.6H.sub.2O to the NaOH in the mixed solution is (0.1-5):(10-50).

3. The method according to claim 1, wherein, in step b), a mass ratio of the Ce(NO.sub.3).sub.3.Math.6H.sub.2O to the CTAB to the SDS is (10-30):(0.1-3):(0.1-3).

4. The method according to claim 1, wherein, a molar ratio of the Ce(NO.sub.3).sub.3.Math.6H.sub.2O to the La(NO.sub.3).sub.3.Math.6H.sub.2O to the Y(NO.sub.3).sub.3.Math.6H.sub.2O is (6-12):(0.5-1.5):(1-3).

5. A catalyst for catalytic reduction of an industrial flue gas SO.sub.2 with CO, prepared by using the following method: a) respectively dissolving Ce(NO.sub.3).sub.3.Math.6H.sub.2O and NaOH in water to obtain a Ce(NO.sub.3).sub.3.Math.6H.sub.2O aqueous solution and a NaOH aqueous solution, and slowly adding the NaOH aqueous solution dropwise into the Ce(NO.sub.3).sub.3.Math.6H.sub.2O aqueous solution for uniform mixing to obtain a mixed solution 1; b) dissolving cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfonate (SDS) in water to obtain a solution, slowly adding the solution into the mixed solution 1 for stirring for 12-15 h, and conducting a hydrothermal reaction at a temperature of 100-110? C. for 24-26 h; c) cooling a reactant obtained after the hydrothermal reaction in step b) to room temperature, filtering the cooled reactant to collect a white precipitate, and sequentially washing, drying and calcining the white precipitate to obtain a CeO.sub.2 nanorod; d) dissolving La(NO.sub.3).sub.3.Math.6H.sub.2O and Y(NO.sub.3).sub.3.Math.6H.sub.2O in water to obtain a mixed solution 2, and adjusting a pH of the mixed solution 2 to 12; adding the CeO.sub.2 nanorod obtained in step c) into the mixed solution 2, placing the mixed solution 2 on a magnetic stirrer for stirring at a constant speed at 30-40? C. for about 4-6 h, heating the mixed solution to 80-90? C., and continuously stirring the mixed solution until the solution is neutral to obtain a catalyst; and drying the catalyst, and calcining the dried catalyst in an air atmosphere in a muffle furnace at 500-600? C. for 4-6 h to obtain a La-Y/CeO.sub.2 catalyst; and e) pulverizing and sieving the La-Y/CeO.sub.2 catalyst, placing particles with a particle size of 60-80 mesh in a quartz tube, and placing the quartz tube in an electric tube furnace; and then conducting sulfurization at 550-600? C. at a heating rate of 5-15? C./min in a mixed gas comprising 1-10% of CO, 1-10% of SO.sub.2 and the balance of N.sub.2 by volume at an air speed of 5,000-8,000 h.sup.?1 for 1-4 h to obtain a target product sulfurized catalyst.

6. The catalyst according to claim 5, wherein, in step a), a mass ratio of the Ce(NO.sub.3).sub.3.Math.6H.sub.2O to the NaOH in the mixed solution is (0.1-5):(10-50).

7. The catalyst according to claim 5, wherein, in step b), a mass ratio of the Ce(NO.sub.3).sub.3.Math.6H.sub.2O to the CTAB to the SDS is (10-30):(0.1-3):(0.1-3).

8. The catalyst according to claim 5, wherein, a molar ratio of the CeO.sub.2 to the La(NO.sub.3).sub.3.Math.6H.sub.2O to the Y(NO.sub.3)3.Math.6H.sub.2O is (6-12):(0.5-1.5):(1-3).

9. A method of using the catalyst prepared by using the method according to claim 1 in catalytic reduction of an industrial flue gas SO.sub.2 with CO to prepare sulfur, comprising: placing 1 mL of a sulfurized catalyst in a 10 mm quartz tube, and placing the quartz tube in an electric tube furnace for a reaction at a temperature of 300-500? C. at a heating rate of 5-15? C./min in a flue gas comprising 0.5-4% of SO.sub.2, 1-8% of CO and 88-98.5% of N.sub.2 at a volumetric air speed of 12,000-15,000 h.sup.?1; and discharging sulfur vapor from a gas outlet of the tube furnace, preserving heat of the sulfur vapor with a heating belt, and condensing the sulfur vapor into sulfur in a cold trap.

10. The method according to claim 9, wherein, after the reaction is completed, 100-120 mL of CS.sub.2 is added into the cold trap and shaken up and down for completely dissolving the sulfur in a CS.sub.2 solution, an obtained mixed solution is placed in a distillation flask, and the distillation flask is heated at 50-60? C. in a water bath kettle; the CS.sub.2 is vaporized after being heated to obtain vapor, and the vapor enters a condenser through a branch tube and is condensed in a conical flask; and sulfur obtained in the distillation flask is collected.

11. The method according to claim 2, wherein, in step a), a mass ratio of the Ce(NO.sub.3).sub.3.Math.6H.sub.2O to the NaOH in the mixed solution is (1.5-5):(10-40).

12. The method according to claim 3, wherein, in step b), a mass ratio of the Ce(NO.sub.3).sub.3.Math.6H.sub.2O to the CTAB to the SDS is (10-25):(0.5-1.5):(0.5-1.5).

13. The catalyst according to claim 6, wherein, in step a), a mass ratio of the Ce(NO.sub.3).sub.3.Math.6H.sub.2O to the NaOH in the mixed solution is (1.5-5):(10-40).

14. The catalyst according to claim 7, wherein, in step b), a mass ratio of the Ce(NO.sub.3).sub.3.Math.6H.sub.2O to the CTAB to the SDS is (10-25):(0.5-1.5):(0.5-1.5).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram showing a device used in the present invention.

(2) Callouts in the FIGURE are as follows: 1, 99.999% of N.sub.2; 2, 99.999% of SO.sub.2; 3, 99.999% of CO; 4, pressure relief valve; 5, mass flowmeter; 6, mixing chamber; 7, quartz tube; 8, high-temperature tube furnace; 9, catalyst fixed bed; 10, cold trap; 11, ice water bath; 12, sulfur dioxide analyzer; 13, gas chromatograph; and 14, tail gas treatment unit.

DETAILED DESCRIPTION

(3) The present invention is further described below with reference to embodiments, but the protection scope of the present invention is not limited thereto.

Example 1

(4) a) 1.74 g of Ce(NO.sub.3).sub.3.Math.6H.sub.2O and 16 g of NaOH were respectively dissolved in 35 mL and 30 mL of H.sub.2O to obtain a Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 30 min to obtain a mixed solution 1.

(5) b) 0.1 g of CTAB and 0.1 g of SDS were dissolved in 5 mL of distilled water to obtain a solution. The solution was added dropwise into the mixed solution 1 for stirring for 12 h and then loaded into an autoclave for a hydrothermal reaction at 110? C. for 24 h.

(6) c) Cooling was conducted to room temperature. Filtration was conducted to collect a white precipitate. The white precipitate was washed to neutral with deionized water. The washed white precipitate was dried in a drying oven at 60? C. for 12 h and then calcined in a muffle furnace at 500? C. for 5 h to obtain a CeO.sub.2 nanorod.

(7) d) 0.31 g of La(NO.sub.3).sub.3.Math.6H.sub.2O and 0.43 g of Y(NO.sub.3).sub.3.Math.6H.sub.2O were dissolved in distilled water to obtain a mixed solution. 25% ammonia was added. Stirring was conducted for 2 h to adjust the pH of the mixed solution to 12 to obtain a mixed solution 2. 0.8 g of the CeO.sub.2 nanorod was added into the mixed solution 2. The mixed solution 2 was placed on a magnetic stirrer for stirring at a constant speed at 30? C. for about 4 h and then heated to 80? C. Stirring was conducted continuously until the pH was 7 to obtain a catalyst. The catalyst was dried at 120? C. for 12 h and then calcined in an air atmosphere in a muffle furnace at 500? C. for 4 h to obtain a LaY/CeO.sub.2 catalyst. A molar ratio of the CeO.sub.2 to the La(NO.sub.3).sub.3.Math.6H.sub.2O to the Y(NO.sub.3).sub.3.Math.6H.sub.2O was 6.5:1:1.6.

(8) e) The pre-calcined catalyst was pulverized and sieved. 1.00 mL of particles with a particle size of 60 mesh were placed in a 10 mm quartz tube. The quartz tube was placed in an electric tube furnace. Sulfurization was conducted at 550? C. at a heating rate of 10? C./min in a mixed gas including 6% of CO, 3% of SO.sub.2 and the balance of N.sub.2 by volume at an air speed of 6,000 h.sup.?1 for 2 h to obtain a sulfurized catalyst.

Example 2

(9) a) 3.48 g of Ce(NO.sub.3).sub.3.Math.6H.sub.2O and 32.0 g of NaOH were respectively dissolved in 70 mL and 60 mL of H.sub.2O to obtain a Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 40 min to obtain a mixed solution 1.

(10) b) 0.2 g of CTAB and 0.2 g of SDS were dissolved in 5 mL of distilled water to obtain a solution. The solution was added dropwise into the mixed solution 1 for stirring for 15 h and then loaded into an autoclave for a hydrothermal reaction at 110? C. for 26 h.

(11) c) Cooling was conducted to room temperature. Filtration was conducted to collect a white precipitate. The white precipitate was washed to neutral with deionized water. The washed white precipitate was dried in a drying oven at 70? C. for 14 h and then calcined in a muffle furnace at 550? C. for 6 h to obtain a CeO.sub.2 nanorod.

(12) d) 0.31 g of La(NO.sub.3).sub.3.Math.6H.sub.2O and 0.43 g of Y(NO.sub.3).sub.3.Math.6H.sub.2O were dissolved in distilled water to obtain a mixed solution. 25% ammonia was added. Stirring was conducted for 2 h to adjust the pH of the mixed solution to 12 to obtain a mixed solution 2. 0.8 g of the CeO.sub.2 nanorod was added into the mixed solution 2. The mixed solution 2 was placed on a magnetic stirrer for stirring at a constant speed at 30? C. for about 4 h and then heated to 90? C. Stirring was conducted continuously until the pH was about 7 to obtain a catalyst. The catalyst was dried at 120? C. for 12 h and then calcined in an air atmosphere in a muffle furnace at 600? C. for 4 h to obtain a LaY/CeO.sub.2 catalyst. A molar ratio of the CeO.sub.2 to the La(NO.sub.3).sub.3.Math.6H.sub.2O to the Y(NO.sub.3).sub.3.Math.6H.sub.2O was 6.5:1:1.6.

(13) e) The pre-calcined catalyst was pulverized and sieved. 1.00 mL of particles with a particle size of 80 mesh were placed in a 10 mm quartz tube. The quartz tube was placed in an electric tube furnace. The catalyst was sulfurized at 550? C. at a heating rate of 10? C./min in a mixed gas including 6% of CO, 3% of SO.sub.2 and the balance of N.sub.2 by volume at an air speed of 6,000 h.sup.?1 for 2 h to obtain a sulfurized catalyst.

Example 3

(14) a) 1.74 g of Ce(NO.sub.3).sub.3.Math.6H.sub.2O and 16.0 g of NaOH were respectively dissolved in 35 mL and 30 mL of H.sub.2O to obtain a Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 40 min to obtain a mixed solution 1.

(15) b) 0.1 g of CTAB and 0.1 g of SDS were dissolved in 5 mL of distilled water to obtain a solution. The solution was added dropwise into the mixed solution 1 for stirring for 12 h and then loaded into an autoclave for a hydrothermal reaction at 110? C. for 24 h.

(16) c) Cooling was conducted to room temperature. Filtration was conducted to collect a white precipitate. The white precipitate was washed to neutral with deionized water. The washed white precipitate was dried in a drying oven at 60? C. for 12 h and then calcined in a muffle furnace at 500? C. for 5 h to obtain a CeO.sub.2 nanorod.

(17) d) 0.25 g of La(NO.sub.3).sub.3.Math.6H.sub.2O and 0.52 g of Y(NO.sub.3).sub.3.Math.6H.sub.2O were dissolved in distilled water to obtain a mixed solution. 25% ammonia was added. Stirring was conducted for 2 h to adjust the pH of the mixed solution to 12 to obtain a mixed solution 2. 0.8 g of the CeO.sub.2 nanorod was added into the mixed solution 2. The mixed solution 2 was placed on a magnetic stirrer for stirring at a constant speed at 30? C. for about 4 h and then heated to 80? C. Stirring was conducted continuously until the pH was about 7 to obtain a catalyst. The catalyst was dried at 120? C. for 12 h and then calcined in an air atmosphere in a muffle furnace at 500? C. for 4 h to obtain a LaY/CeO.sub.2 catalyst. A molar ratio of the CeO.sub.2 to the La(NO.sub.3).sub.3.Math.6H.sub.2O to the Y(NO.sub.3).sub.3.Math.6H.sub.2O was 8.1:1:2.4.

(18) e) The pre-calcined catalyst was pulverized and sieved. 1.00 mL of particles with a particle size of 60 mesh were placed in a 10 mm quartz tube. The quartz tube was placed in an electric tube furnace. The catalyst was sulfurized at 550? C. at a heating rate of 10? C./min in a mixed gas including 6% of CO, 3% of SO.sub.2 and the balance of N.sub.2 by volume at an air speed of 6,000 h.sup.?1 for 2 h to obtain a sulfurized catalyst.

Example 4

(19) a) 3.48 g of Ce(NO.sub.3).sub.3.Math.6H.sub.2O and 32.0 g of NaOH were respectively dissolved in 70 mL and 60 mL of H.sub.2O to obtain a Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 40 min to obtain a mixed solution 1.

(20) b) 0.2 g of CTAB and 0.2 g of SDS were dissolved in 5 mL of distilled water to obtain a solution. The solution was added dropwise into the mixed solution 1 for stirring for 14 h and then loaded into an autoclave for a hydrothermal reaction at 110? C. for 26 h.

(21) c) Cooling was conducted to room temperature. Filtration was conducted to collect a white precipitate. The white precipitate was washed to neutral with deionized water. The washed white precipitate was dried in a drying oven at 70? C. for 14 h and then calcined in a muffle furnace at 550? C. for 6 h to obtain a CeO.sub.2 nanorod.

(22) d) 0.24 g of La(NO.sub.3).sub.3.Math.6H.sub.2O and 0.32 g of Y(NO.sub.3).sub.3.Math.6H.sub.2O were dissolved in distilled water to obtain a mixed solution. 25% ammonia was added. Stirring was conducted for 2 h to adjust the pH of the mixed solution to 12 to obtain a mixed solution 2. 0.85 g of the CeO.sub.2 nanorod was added into the mixed solution 2. The mixed solution 2 was placed on a magnetic stirrer for stirring at a constant speed at 30? C. for about 4 h and then heated to 90? C. Stirring was conducted continuously until the pH was about 7 to obtain a catalyst. The catalyst was dried at 120? C. for 12 h and then calcined in an air atmosphere in a muffle furnace at 600? C. for 4 h to obtain a LaY/CeO.sub.2 catalyst. A molar ratio of the CeO.sub.2 to the La(NO.sub.3).sub.3.Math.6H.sub.2O to the Y(NO.sub.3).sub.3.Math.6H.sub.2O was 8.9:1:1.5.

(23) e) The pre-calcined catalyst was pulverized and sieved. 1.00 mL of particles with a particle size of 60 mesh were placed in a 10 mm quartz tube. The quartz tube was placed in an electric tube furnace. The catalyst was sulfurized at 550? C. at a heating rate of 10? C./min in a mixed gas including 6% of CO, 3% of SO.sub.2 and the balance of N.sub.2 by volume at an air speed of 6,000 h.sup.?1 for 2 h to obtain a sulfurized catalyst.

Comparative Example 1

(24) a) 1.74 g of Ce(NO.sub.3).sub.3.Math.6H.sub.2O and 16 g of NaOH were respectively dissolved in 35 mL and 30 mL of H.sub.2O to obtain a Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 30 min to obtain a mixed solution 1.

(25) b) 0.1 g of CTAB and 0.1 g of SDS were dissolved in 5 mL of distilled water to obtain a solution. The solution was added dropwise into the mixed solution 1 for stirring for 12 h and then loaded into an autoclave for a hydrothermal reaction at 110? C. for 24 h.

(26) c) Cooling was conducted to room temperature. Filtration was conducted to collect a white precipitate. The white precipitate was washed to neutral with deionized water. The washed white precipitate was dried in a drying oven at 60? C. for 12 h and then calcined in a muffle furnace at 500? C. for 5 h to obtain a CeO.sub.2 nanorod.

(27) d) The pre-calcined CeO.sub.2 nanorod was pulverized and sieved. 1.00 mL of particles with a particle size of 60 mesh were placed in a 10 mm quartz tube. The quartz tube was placed in an electric tube furnace.

(28) e) The catalyst was sulfurized at 550? C. at a heating rate of 10? C./min in a mixed gas including 6% of CO, 3% of SO.sub.2 and the balance of N.sub.2 by volume at an air speed of 6,000 h.sup.?1 for 2 h to obtain a sulfurized catalyst.

Comparative Example 2

(29) a) 1.74 g of Ce(NO.sub.3).sub.3.Math.6H.sub.2O and 16 g of NaOH were respectively dissolved in 35 mL and 30 mL of H.sub.2O to obtain a Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 30 min to obtain a mixed solution 1.

(30) b) 0.1 g of CTAB and 0.1 g of SDS were dissolved in 5 mL of distilled water to obtain a solution. The solution was added dropwise into the mixed solution 1 for stirring for 12 h and then loaded into an autoclave for a hydrothermal reaction at 110? C. for 24 h.

(31) c) Cooling was conducted to room temperature. Filtration was conducted to collect a white precipitate. The white precipitate was washed to neutral with deionized water. The washed white precipitate was dried in a drying oven at 60? C. for 12 h and then calcined in a muffle furnace at 500? C. for 5 h to obtain a CeO.sub.2 nanorod.

(32) d) 0.62 g of La(NO.sub.3).sub.3.Math.6H.sub.2O was dissolved in distilled water to obtain a mixed solution. 25% ammonia was added. Stirring was conducted for 2 h to adjust the pH of the mixed solution to 12. Then stirring was conducted at a constant speed at room temperature for 1 h to obtain a mixed solution.

(33) e) 0.8 g of the CeO.sub.2 nanorod was added into the mixed solution obtained in step d). The mixed solution was placed on a magnetic stirrer for stirring at a constant speed at 30? C. for about 4 h and then heated to 80? C. Stirring was conducted continuously until the pH was about 7 to obtain a catalyst. The catalyst was dried at 120? C. for 12 h and then calcined in an air atmosphere in a muffle furnace at 500? C. for 4 h to obtain a La/CeO.sub.2 catalyst. A molar ratio of the CeO.sub.2 to the La(NO.sub.3).sub.3.Math.6H.sub.2O was 6.5:2.

(34) f) The pre-calcined catalyst was pulverized and sieved. 1.00 mL of particles with a particle size of 60 mesh were placed in a 10 mm quartz tube. The quartz tube was placed in an electric tube furnace.

(35) g) The catalyst was sulfurized at 550? C. at a heating rate of 10? C./min in a mixed gas including 6% of CO, 3% of SO.sub.2 and the balance of N.sub.2 by volume at an air speed of 6,000 h.sup.?1 for 2 h to obtain a sulfurized catalyst.

Comparative Example 3

(36) a) 1.74 g of Ce(NO.sub.3).sub.3.Math.6H.sub.2O and 16 g of NaOH were respectively dissolved in 35 mL and 30 mL of H.sub.2O to obtain a Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO.sub.3).sub.3.Math.6H.sub.2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 30 min to obtain a mixed solution 1.

(37) b) 0.1 g of CTAB and 0.1 g of SDS were dissolved in 5 mL of distilled water to obtain a solution. The solution was added dropwise into the mixed solution 1 for stirring for 12 h and then loaded into an autoclave for a hydrothermal reaction at 110? C. for 24 h.

(38) c) Cooling was conducted to room temperature. Filtration was conducted to collect a white precipitate. The white precipitate was washed to neutral with deionized water. The washed white precipitate was dried in a drying oven at 60? C. for 12 h and then calcined in a muffle furnace at 500? C. for 5 h to obtain a CeO.sub.2 nanorod.

(39) d) 0.86 g of Y(NO.sub.3).sub.3.Math.6H.sub.2O was dissolved in distilled water to obtain a mixed solution. 25% ammonia was added. Stirring was conducted for 2 h to adjust the pH of the mixed solution to 12. Then stirring was conducted at a constant speed at room temperature for 1 h to obtain a mixed solution.

(40) e) 0.8 g of the CeO.sub.2 nanorod was added into the mixed solution obtained in step d). The mixed solution was placed on a magnetic stirrer for stirring at a constant speed at 30? C. for about 4 h and then heated to 80? C. Stirring was conducted continuously until the pH was about 7 to obtain a catalyst. The catalyst was dried at 120? C. for 12 h and then calcined in an air atmosphere in a muffle furnace at 500? C. for 4 h to obtain a Y/CeO.sub.2 catalyst. A molar ratio of the CeO.sub.2 to the Y(NO.sub.3).sub.3.Math.6H.sub.2O was 6.2:3.

(41) f) The pre-calcined catalyst was pulverized and sieved. 1.00 mL of particles with a particle size of 60 mesh were placed in a 10 mm quartz tube. The quartz tube was placed in an electric tube furnace.

(42) g) The catalyst was sulfurized at 550? C. at a heating rate of 10? C./min in a mixed gas including 6% of CO, 3% of SO.sub.2 and the balance of N.sub.2 by volume at an air speed of 6,000 h.sup.?1 for 2 h to obtain a sulfurized catalyst.

(43) Performance Test

(44) The performance of a catalyst was tested by using a device shown in FIG. 1. 1 mL of a pre-sulfurized LaY/CeO.sub.2 catalyst was placed in a 10 mm quartz tube 7. The quartz tube 7 was fixed to a catalyst fixed bed 9 and then placed in a high-temperature electric tube furnace 8. A reaction was conducted in a flue gas including 1% of SO.sub.2, 2% of CO and 97% of N.sub.2 at a volumetric air speed of 12,000 h.sup.?1. The reaction was conducted at a heating rate of 10? C./min and a temperature of 300? C., 350? C., 400? C., 450? C. and 500? C. separately. According to a program of the high-temperature tube furnace 8, heating was conducted to a target temperature, and then heat preservation was conducted. After the temperature was table, a tail gas was detected. The concentration of SO.sub.2 was tested by using a sulfur dioxide analyzer 12. The concentration of COS was tested by using a gas chromatograph 13 (Thermo Fisher Scientific Co., Ltd.). Sulfur vapor was discharged from a gas outlet of the high-temperature tube furnace 8. Heat of the sulfur vapor was preserved with a heating belt. Then the sulfur vapor was condensed into sulfur in a cold trap 10. After the reaction was completed, 100-120 mL of CS.sub.2 was added into the cold trap 10 and shaken up and down for completely dissolving the sulfur in a CS.sub.2 solution. An obtained mixed solution was placed in a distillation flask. The distillation flask was heated at 50? C. in a water bath kettle. The CS.sub.2 was vaporized after being heated to obtain vapor. The vapor entered a condenser through a branch tube and was condensed in a conical flask. After distillation was completed, sulfur obtained in the distillation flask was collected.

(45) $\mathrm{Conversion}\mathrm{rate}\%=\frac{\mathrm{Concentration}\mathrm{of}{\mathrm{SO}}_2\mathrm{at}\mathrm{inlet}-\mathrm{Concentration}\mathrm{of}{\mathrm{SO}}_2\mathrm{at}\mathrm{outlet}}{\mathrm{Concentration}\mathrm{of}{\mathrm{SO}}_2\mathrm{at}\mathrm{inlet}}?100\%$$\mathrm{Selectivity}\%=\frac{\begin{array}{c}\mathrm{Concentration}\mathrm{of}{\mathrm{SO}}_2\mathrm{at}\mathrm{inlet}-\\ \mathrm{Concentration}\mathrm{of}{\mathrm{SO}}_2\mathrm{at}\mathrm{outlet}-\\ \mathrm{Concentration}\mathrm{of}\mathrm{COS}\mathrm{at}\mathrm{outlet}\end{array}}{\mathrm{Concentration}\mathrm{of}{\mathrm{SO}}_2\mathrm{at}\mathrm{inlet}}?100\%$

(46) Test results are as follows.

(47) TABLE-US-00001 Reaction Conversion Selectivity of temperature rate of SO.sub.2 elemental S Sample (? C.) (%) (%) Example 1 300 68.2% 62.3% 350 85.3% 80.1% 400 97.6% 92.1% 450 97.3% 92.5% 500 97.8% 93.4% Example 2 300 64.5% 59.8% 350 82.6% 77.9% 400 95.4% 91.3% 450 96.7% 93.5% 500 96.4% 92.9% Example 3 300 66.3% 62.7% 350 79.8% 74.8% 400 95.7% 91.5% 450 96.2% 93.5% 500 96.7% 93.7% Example 4 300 66.3% 61.6% 350 84.5% 80.1% 400 97.1% 93.5% 450 97.2% 94.1% 500 96.9% 92.9% Comparative 300 32.6% 28.4% Example 1 350 50.8% 45.9% 400 62.7% 58.5% 450 67.8% 63.3% 500 74.4% 70.6% Comparative 300 41.8% 37.4% Example 2 350 53.3% 48.2% 400 66.9% 63.1% 450 72.6% 67.9% 500 84.8% 81.4% Comparative 300 37.4% 31.6% Example 3 350 46.7% 42.4% 400 67.5% 61.7% 450 79.4% 75.3% 500 82.1% 78.3%