Patent Grant
12090467
The present invention relates to the field of atmospheric purification, and specifically relates to a catalyst for catalytic reduction of an industrial flue gas SO2 with CO to prepare sulfur, a method for preparing the same and use thereof.
As a colorless and inflammable gas with a pungent odor, SO2 is a major air pollutant with wide distribution and great harm. SO2 is mainly produced by combustion of sulfur coal and petroleum, petroleum refining, non-ferrous metal metallurgy and manufacturing of sulfuric acid. With rapid development of a flue gas desulfurization industry, pollution caused by the industrial flue gas SO2 is effectively controlled, and meanwhile, a large number of desulfurization by-products are also produced. According to different desulfurization processes, the desulfurization by-products mainly include gypsum obtained by using a wet desulfurization process and ash obtained by using a semi-dry desulfurization process. However, as the desulfurization processes have monotonous routes, no enough attention has been paid to disposal and consumption of the desulfurization by-products. In some power plants, the desulfurization by-product gypsum has nowhere to be consumed, and can only be stacked and discarded. As a large number of the by-products are still stacked in the open air, not only are land resources occupied, but also secondary pollution is caused to the environment. In addition, as the desulfurization by-products are not effectively used, waste of resources is caused.
At present, conventional desulfurization methods have relatively mature processes and stable desulfurization efficiency, but serious secondary pollution, equipment corrosion and other problems still exist. Catalytic reduction desulfurization refers to a process of reducing the industrial flue gas SO2 in a flue gas to elemental sulfur with reducing agents such as CO, C, H2, H2S, etc. The flue gas contains a certain amount of the CO. In recent years, with development and application of new sulfur products such as polymerized sulfur, sulfur-coated urea and sulfur cement, the demand for sulfur in industries such as rubber, pesticides, building materials, textiles, chemical engineering, dyes and daily chemicals in China is rapidly increased, and the sulfur is widely used in paving asphalt. At present, the sulfur production in China is far from meeting the demand. Thus, a large amount of the sulfur is imported into China every year. According to a catalytic reduction desulfurization process, not only can the industrial flue gas SO2 be effectively removed, but also secondary pollution cannot be caused by the produced sulfur, the problem of shortage of sulfur resources in China can be solved, and wastes are turned into treasures.
According to an invention patent titled “METHOD FOR PREPARING COMPOSITE CATALYST FOR CATALYTIC REDUCTION OF SO2 WITH CO AND METHOD FOR RECOVERING SULFUR” (with a publication number of CN 107497453A), a method for preparing a composite catalyst for catalytic reduction of SO2 with CO and a method for recovering sulfur are provided. According to the method, a perovskite-type composite catalyst La1-xCexCoO3 (0≤x≤1) is prepared by using a microwave-assisted in-situ carbon template stabilization method. The composite catalyst has high activity stability and can be used for preparing the sulfur with high purity. However, as the elemental sulfur is mixed with the catalyst and then extracted, the method has a complicated process. According to an invention patent titled “CATALYST FOR REDUCTION OF SO2 WITH CO, METHOD FOR PREPARING SAME AND USE THEREOF” (with a publication number of CN 109999804B), a catalyst for reduction of SO2 with CO, a method for preparing same and use thereof are provided. According to the method, a lanthanum oxide and a cerium oxide are doped on the basis of an aluminum oxide carrier, and a certain amount of one or more of a zirconium oxide, an iron oxide, a manganese oxide, a cobalt oxide, a chromium oxide, a zinc oxide and a tin oxide are added to serve as a catalytic promoter. The catalyst has high catalytic activity and sulfur selectivity, but components of the catalyst are complex. The preparation method has a complicated preparation process and low economical efficiency.
The present invention provides a catalyst for catalytic reduction of an industrial flue gas SO2 with CO to prepare sulfur, a method for preparing the same and use thereof. A CeO2 nanorod is prepared by using a hydrothermal method to serve as a carrier, the loading strength of active components is improved, and the active components La and Y are loaded on the CeO2 nanocarrier by using an ammonia distillation method.
The objectives of the present invention may be achieved by the following technical solutions:
A method for preparing a catalyst for catalytic reduction of an industrial flue gas SO2 with CO includes the following steps:
A catalyst for catalytic reduction of an industrial flue gas SO2 with CO is prepared by using the following method:
e) pulverizing and sieving the La—Y/CeO2 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 including 1-10% of CO, 1-10% of SO2 and the balance of N2 by volume at an air speed of 5,000-8,000 h−1 for 1-4 h to obtain a target product sulfurized catalyst.
In a technical solution of the present invention, in step a), a mass ratio of the Ce(NO3)3·6H2O to the NaOH in the mixed solution is (0.1-5):(10-50).
In some preferred technical solutions, in step a), a mass ratio of the Ce(NO3)3·6H2O to the NaOH in the mixed solution is (1.5-5):(10-40).
In a technical solution of the present invention, in step b), a mass ratio of the Ce(NO3)3·6H2O to the CTAB to the SDS is (10-30):(0.1-3):(0.1-3).
In some preferred technical solutions, a mass ratio of the Ce(NO3)3·6H2O to the CTAB to the SDS is (10-25):(0.5-1.5):(0.5-1.5).
In a technical solution of the present invention, in step d), a molar ratio of the Ce(NO3)3·6H2O to the La(NO3)3·6H2O to the Y(NO3)3·6H2O is (6-12):(0.5-1.5):(1-3).
In step d), a molar ratio of the CeO2 to the La(NO3)3·6H2O to the Y(NO3)3·6H2O is (6-12):(0.5-1.5):(1-3).
A method of using the catalyst prepared by using the method above in catalytic reduction of an industrial flue gas SO2 with CO to prepare sulfur is provided. The method includes: 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 including 0.5-4% of SO2, 1-8% of CO and 88-98.5% of N2 at a volumetric air speed of 12,000-15,000 h−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.
According to the method above, after the reaction is completed, 100-120 mL of CS2 is added into the cold trap and shaken up and down for completely dissolving the sulfur in a CS2 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 CS2 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. Sulfur obtained in the distillation flask is collected. Beneficial effects of the present invention:
(1) A catalytic reduction desulfurization process is simple, no secondary pollution is caused, and the elemental sulfur can be recovered to achieve the purpose of turning wastes into treasures. The desulfurization method is the best one for organically combining environmental benefits and resource benefits among various desulfurization technologies at present.
(2) China has concentrated distribution of rare earth reserves, accounts for a large proportion of total rare earth reserves, and is well-known as a rare earth country. Ceria is an oxide catalyst with the highest activity among rare earth oxides. During reduction of an industrial flue gas SO2 with CO, the cheap and abundant nano-CeO2 is used as a carrier to load La and Y, and great significance is brought to development of rare earth resources.
(3) The CTAB and the SDS are added in a certain amount in a strong alkali environment. The CeO2 nanorod with specific morphology is prepared by using the hydrothermal method to serve as the carrier. The obtained catalyst has many oxygen vacancies, large specific surface area, high catalytic activity, a desulfurization rate of 96-98% and a sulfur recovery rate of 92-95%.
Callouts in the FIGURE are as follows: 1, 99.999% of N2; 2, 99.999% of SO2; 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.
The present invention is further described below with reference to embodiments, but the protection scope of the present invention is not limited thereto.
a) 1.74 g of Ce(NO3)3·6H2O and 16 g of NaOH were respectively dissolved in 35 mL and 30 mL of H2O to obtain a Ce(NO3)3·6H2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO3)3·6H2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 30 min to obtain a mixed solution 1.
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.
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 CeO2 nanorod.
d) 0.31 g of La(NO3)3·6H2O and 0.43 g of Y(NO3)3·6H2O 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 CeO2 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 La—Y/CeO2 catalyst. A molar ratio of the CeO2 to the La(NO3)3·6H2O to the Y(NO3)3·6H2O was 6.5:1:1.6.
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 SO2 and the balance of N2 by volume at an air speed of 6,000 h−1 for 2 h to obtain a sulfurized catalyst.
a) 3.48 g of Ce(NO3)3·6H2O and 32.0 g of NaOH were respectively dissolved in 70 mL and 60 mL of H2O to obtain a Ce(NO3)3·6H2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO3)3·6H2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 40 min to obtain a mixed solution 1.
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.
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 CeO2 nanorod.
d) 0.31 g of La(NO3)3·6H2O and 0.43 g of Y(NO3)3·6H2O 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 CeO2 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 La—Y/CeO2 catalyst. A molar ratio of the CeO2 to the La(NO3)3·6H2O to the Y(NO3)3·6H2O was 6.5:1:1.6.
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 SO2 and the balance of N2 by volume at an air speed of 6,000 h−1 for 2 h to obtain a sulfurized catalyst.
a) 1.74 g of Ce(NO3)3·6H2O and 16.0 g of NaOH were respectively dissolved in 35 mL and 30 mL of H2O to obtain a Ce(NO3)3·6H2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO3)3·6H2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 40 min to obtain a mixed solution 1.
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.
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 CeO2 nanorod.
d) 0.25 g of La(NO3)3·6H2O and 0.52 g of Y(NO3)3·6H2O 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 CeO2 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 La—Y/CeO2 catalyst. A molar ratio of the CeO2 to the La(NO3)3·6H2O to the Y(NO3)3·6H2O was 8.1:1:2.4.
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 SO2 and the balance of N2 by volume at an air speed of 6,000 h−1 for 2 h to obtain a sulfurized catalyst.
a) 3.48 g of Ce(NO3)3·6H2O and 32.0 g of NaOH were respectively dissolved in 70 mL and 60 mL of H2O to obtain a Ce(NO3)3·6H2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO3)3·6H2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 40 min to obtain a mixed solution 1.
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.
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 CeO2 nanorod.
d) 0.24 g of La(NO3)3·6H2O and 0.32 g of Y(NO3)3·6H2O 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 CeO2 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 La—Y/CeO2 catalyst. A molar ratio of the CeO2 to the La(NO3)3·6H2O to the Y(NO3)3·6H2O was 8.9:1:1.5.
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 SO2 and the balance of N2 by volume at an air speed of 6,000 h−1 for 2 h to obtain a sulfurized catalyst.
a) 1.74 g of Ce(NO3)3·6H2O and 16 g of NaOH were respectively dissolved in 35 mL and 30 mL of H2O to obtain a Ce(NO3)3·6H2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO3)3·6H2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 30 min to obtain a mixed solution 1.
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.
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 CeO2 nanorod.
d) The pre-calcined CeO2 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.
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 SO2 and the balance of N2 by volume at an air speed of 6,000 h−1 for 2 h to obtain a sulfurized catalyst.
a) 1.74 g of Ce(NO3)3·6H2O and 16 g of NaOH were respectively dissolved in 35 mL and 30 mL of H2O to obtain a Ce(NO3)3·6H2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO3)3·6H2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 30 min to obtain a mixed solution 1.
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.
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 CeO2 nanorod.
d) 0.62 g of La(NO3)3·6H2O 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.
e) 0.8 g of the CeO2 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/CeO2 catalyst. A molar ratio of the CeO2 to the La(NO3)3·6H2O was 6.5:2.
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.
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 SO2 and the balance of N2 by volume at an air speed of 6,000 h−1 for 2 h to obtain a sulfurized catalyst.
a) 1.74 g of Ce(NO3)3·6H2O and 16 g of NaOH were respectively dissolved in 35 mL and 30 mL of H2O to obtain a Ce(NO3)3·6H2O solution and a NaOH solution. The NaOH solution was slowly added dropwise into the Ce(NO3)3·6H2O solution to obtain a mixed solution. The mixed solution was stirred on a magnetic stirrer for 30 min to obtain a mixed solution 1.
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.
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 CeO2 nanorod.
d) 0.86 g of Y(NO3)3·6H2O 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.
e) 0.8 g of the CeO2 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/CeO2 catalyst. A molar ratio of the CeO2 to the Y(NO3)3·6H2O was 6.2:3.
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.
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 SO2 and the balance of N2 by volume at an air speed of 6,000 h−1 for 2 h to obtain a sulfurized catalyst.
Performance Test
The performance of a catalyst was tested by using a device shown in
Test results are as follows.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202110870394.6 | Jul 2021 | CN | national |
| Number | Date | Country |
|---|---|---|
| 107497453 | Dec 2017 | CN |
| 108380220 | Aug 2018 | CN |
| 112169785 | Jan 2021 | CN |
| 9112201 | Aug 1991 | WO |
| Entry |
|---|
| Abstract, English language abstract and translation of CN109999804B, published Jul. 17, 2020. |
| Number | Date | Country | |
|---|---|---|---|
| 20230043657 A1 | Feb 2023 | US |
