SCR catalyst

Abstract

The present invention relates to a catalyst comprising at least one oxide of vanadium, at least one oxide of tungsten, at least one oxide of cerium, at least one oxide of titanium and at least one oxide of antimony, and an exhaust system containing said oxides.

Claims

1. A method of making a catalyst having at least one oxide of vanadium in an amount of 2 to 6 wt %, at least one oxide of tungsten in an amount of 0.5 to 2 wt %, at least one oxide of cerium in an amount of 2 to 4 wt %, at least one oxide of antimony in an amount of 1 to 7 wt %, at least one oxide of silicon in an amount of 0 wt % or 2 to 7 wt %, and at least one oxide of titanium in an amount is measured so as to result in a total of 100 wt %, in each case based on the total weight of the catalyst and calculated as V.sub.2O.sub.5, WO.sub.3, CeO.sub.2, Sb.sub.2O.sub.5, TiO.sub.2, or, if the at least one oxide of silicon is present, SiO.sub.2, said method comprising: obtaining oxides of vanadium, tungsten, cerium, antimony, titanium, and, if present, silicon, forming a mixture of the oxides, and calcining the mixture.

2. The method of claim 1, wherein the oxides are provided in powder form.

3. The method of claim 1, wherein the mixture is a slurry of the oxides in water, and the method further comprises drying the slurry before calcining.

4. The method of claim 1, wherein a portion of the oxides are provided in the mixture in the form of an aqueous solution.

5. The method of claim 1, wherein the mixture comprises oxides of tungsten, cerium, antimony, and titanium that have been impregnated with a vanadium oxide.

6. The method of claim 1, wherein the mixture comprises oxides of vanadium, cerium, antimony, and titanium that have been impregnated with an oxide of tungsten.

7. The method of claim 1, wherein at least two oxides in the mixture are provided as one oxide doped with the other oxide.

8. The method of claim 1, wherein two or more oxides are provided in the mixture as a mixed oxide.

9. The method of claim 1, wherein the mixture comprises a titanium dioxide doped with silicon dioxide and tungsten trioxide, and impregnated with oxides of vanadium and antimony.

10. The method of claim 1, wherein the mixture contains at least one oxide of silicon.

11. The method of claim 1, wherein the mixture further comprises at least one oxide of molybdenum, niobium, zirconium, tantalum, and/or hafnium.

12. The method of claim 11, wherein the amount of the at least one oxide of molybdenum, niobium, zirconium, tantalum, and/or hafnium is 0.5 to 20 wt % based on the total the weight of the mixture and calculated as MoO.sub.3, Nb.sub.2O.sub.5, ZrO.sub.2, Ta.sub.2O.sub.5, or HfO.sub.2.

13. The method of claim 1, which comprises forming the mixture by dispersing titanium dioxide doped with 5 wt % silicon dioxide in water, and adding vanadium dioxide, tungsten trioxide, cerium dioxide, and antimony pentoxide thereto.

14. The method of claim 13, wherein the added amounts of vanadium dioxide, tungsten trioxide, cerium dioxide, and antimony pentoxide result in a catalyst composition comprising 86.00 wt % TiO.sub.2, 4.50 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 1.00 wt % WO.sub.3, 2.00 wt % CeO.sub.2, and 2.75 wt % Sb.sub.2O.sub.5.

Description

(1) The invention is explained below in more detail by means of figures and examples. The following are shown:

(2) FIG. 1: Nitrogen oxide conversions in the standard SCR reaction, measured on the catalyst K1 according to the invention in comparison to comparative catalysts VK1, VK2 VK3, VK4, and VK5 in the fresh state (K1f, VK1f, VK2f, VK3f, VK4f, and VK5f).

(3) FIG. 2: Nitrogen oxide conversions in the standard SCR reaction, measured on the catalyst K1 according to the invention in comparison to comparative catalysts VK1, VK2, VK3, VK4, and VK5 in the aged state (K1a, VK1a, VK2a, VK3a, VK4a, and VK5a).

(4) FIG. 3: Nitrogen oxide conversions in the fast SCR reaction, measured on the catalyst K1 according to the invention in comparison to comparative catalysts VK1, VK2, VK3, VK4, and VK5 in the fresh state (K1f, VK1f, VK2f, VK3f, VK4f, and VK5f).

(5) FIG. 4: Nitrogen oxide conversions in the fast SCR reaction, measured on the catalyst K1 according to the invention in comparison to comparative catalysts VK1, VK2, VK3, VK4, and VK5 in the aged state (K1a, VK1a, VK2a, VK3a, VK4a, and VK5a).

(6) FIG. 5: Nitrogen oxide conversions in the standard SCR reaction at 200° C. and the fast SCR reaction at 300° C. versus the WO.sub.3 content, measured on the catalyst K1 according to the invention in comparison to comparative catalysts VK4, VK6, and VK7 in the fresh and aged states.

(7) FIG. 6: Nitrogen oxide conversions in the standard SCR reaction at 200° C. and the fast SCR reaction at 300° C. versus CeO.sub.2 content, measured on the catalyst K1 according to the invention in comparison to comparative catalysts VK3 and VK8 in the fresh and aged states.

(8) FIG. 7: Nitrogen oxide conversions in the standard SCR reaction at 200° C. and the fast SCR reaction at 300° C. versus Sb.sub.2O.sub.5 content, measured on the catalyst K1 according to the invention in comparison to comparative catalysts VK2, VK9, and VK10 in the fresh and aged states.

EXAMPLE 1

(9) a) A commercially available titanium dioxide in the anatase form doped with 5 wt % silicon dioxide was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), cerium dioxide (CeO.sub.2), and antimony pentoxide (Sb.sub.2O.sub.5) were added in amounts so as to result in a catalyst of the composition 86.00 wt % TiO.sub.2, 4.50 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 1.00 wt % WO.sub.3, 2.00 wt % CeO.sub.2, and 2.75 wt % Sb.sub.2O.sub.5 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst K1 thus obtained is present in the fresh state and is therefore referred to hereinafter as K1f. c) The catalyst K1 obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst K1 is then present in the aged state and is referred to hereinafter as K1a.

COMPARATIVE EXAMPLE 1

(10) a) A commercially available titanium dioxide in the anatase form doped with 5 wt % silicon dioxide was dispersed in water, and then vanadium dioxide (VO.sub.2) and tungsten trioxide (WO.sub.3) were added in amounts so as to result in a catalyst of the composition 90.5 wt % TiO.sub.2, 4.75 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 1.00 wt % WO.sub.3 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK1 thus obtained is in the fresh state and is therefore referred to hereinafter as VK1f. c) The VK1a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK1 is then in the aged state and is referred to hereinafter as VK1a.

COMPARATIVE EXAMPLE 2

(11) a) A commercially available titanium dioxide doped with 5 wt % silicon dioxide in the anatase form was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), and cerium dioxide (CeO.sub.2) were added in amounts so as to result in a catalyst of the composition 88.60 wt % TiO.sub.2, 4.65 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 1.00 wt % WO.sub.3, and 2.00 wt % CeO.sub.2 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK2 thus obtained is present in the fresh state and is therefore referred to hereinafter as VK2f. c) The VK2a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK2 is then in the aged state and is referred to hereinafter as VK2a.

COMPARATIVE EXAMPLE 3

(12) a) A commercially available titanium dioxide in the anatase form doped with 5 wt % silicon dioxide was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), and antimony pentoxide were added in amounts so as to result in a catalyst of the composition 87.9 wt % TiO.sub.2, 4.60 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 1.00 wt % WO.sub.3, and 2.75 wt % Sb.sub.2O.sub.5 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK3 thus obtained is in the fresh state and is therefore referred to hereinafter as VK3f. c) The VK3a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK3 is then in the aged state and is referred to hereinafter as VK3a.

COMPARATIVE EXAMPLE 4

(13) a) A commercially available titanium dioxide in the anatase form doped with 5 wt % silicon dioxide was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), and antimony pentoxide were added in amounts so as to result in a catalyst of the composition 86.9 wt % TiO.sub.2, 4.60 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 2.00 wt % CeO.sub.2, and 2.75 wt % Sb.sub.2O.sub.5 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK4 thus obtained is in the fresh state and is therefore referred to hereinafter as VK4f. c) The VK4a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK4 is then in the aged state and is referred to hereinafter as VK4a.

COMPARATIVE EXAMPLE 5

(14) a) A commercially available titanium dioxide in the anatase form was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), cerium dioxide (CeO.sub.2), and antimony pentoxide (Sb.sub.2O.sub.5) were added in amounts so as to result in a catalyst of the composition 90.5 wt % TiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 1.00 wt % WO.sub.3, 2.00 wt % CeO.sub.2, and 2.75 wt % Sb.sub.2O.sub.5 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK5 thus obtained is in the fresh state and is therefore referred to hereinafter as VK5f. c) The VK5a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK5 is then in the aged state and is referred to hereinafter as VK5a.

COMPARATIVE EXAMPLE 6

(15) a) A commercially available titanium dioxide in the anatase form doped with 5 wt % silicon dioxide was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), cerium dioxide (CeO.sub.2), and antimony pentoxide (Sb.sub.2O.sub.5) were added in amounts so as to result in a catalyst of the composition 86.45 wt % TiO.sub.2, 4.55 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 0.50 wt % WO.sub.3, 2.00 wt % CeO.sub.2, and 2.75 wt % Sb.sub.2O.sub.5 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK6 thus obtained is in the fresh state and is therefore referred to hereinafter as VK6f. c) The VK6a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK6 is then in the aged state and is referred to hereinafter as VK6a.

COMPARATIVE EXAMPLE 7

(16) a) A commercially available titanium dioxide in the anatase form doped with 5 wt % silicon dioxide was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), cerium dioxide (CeO.sub.2), and antimony pentoxide (Sb.sub.2O.sub.5) were added in in amounts so as to result in a catalyst of the composition 85.03 wt % TiO.sub.2, 4.47 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 2.00 wt % WO.sub.3, 2.00 wt % CeO.sub.2 and 2.75 wt % Sb.sub.2O.sub.5 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK7 thus obtained is in the fresh state and is therefore referred to hereinafter as VK7f. c) The VK7a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK7 is then in the aged state and is referred to hereinafter as VK7a.

COMPARATIVE EXAMPLE 8

(17) a) A commercially available titanium dioxide in the anatase form doped with 5 wt % silicon dioxide was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), cerium dioxide (CeO.sub.2), and antimony pentoxide (Sb.sub.2O.sub.5) were added in amounts so as to result in a catalyst of the composition 84.07 wt % TiO.sub.2, 4.43 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 1.00 wt % WO.sub.3, 4.00 wt % CeO.sub.2, and 2.75 wt % Sb.sub.2O.sub.5 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK8 thus obtained is in the fresh state and is therefore referred to hereinafter as VK8f. c) The VK8a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK8 is then in the aged state and is referred to hereinafter as VK8a.

COMPARATIVE EXAMPLE 9

(18) a) A commercially available titanium dioxide in the anatase form doped with 5 wt % silicon dioxide was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), cerium dioxide (CeO.sub.2), and antimony pentoxide (Sb.sub.2O.sub.5) were added in amounts so as to result in a catalyst of the composition 84.79 wt % TiO.sub.2, 4.46 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 1.00 wt % WO.sub.3, 2.00 wt % CeO.sub.2, and 4.00 wt % Sb.sub.2O.sub.5 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK9 thus obtained is in the fresh state and is therefore referred to hereinafter as VK9f. c) The VK9a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK9 is then in the aged state and is referred to hereinafter as VK9a.

COMPARATIVE EXAMPLE 10

(19) a) A commercially available titanium dioxide in the anatase form doped with 5 wt % silicon dioxide was dispersed in water, and then vanadium dioxide (VO.sub.2), tungsten trioxide (WO.sub.3), cerium dioxide (CeO.sub.2), and antimony pentoxide (Sb.sub.2O.sub.5) were added in amounts so as to result in a catalyst of the composition 81.94 wt % TiO.sub.2, 4.31 wt % SiO.sub.2, 3.75 wt % V.sub.2O.sub.5, 1.00 wt % WO.sub.3, 2.00 wt % CeO.sub.2, and 7.00 wt % Sb.sub.2O.sub.5 resulted. The slurry was vigorously stirred and then milled in a commercially available agitator bead mill. b) The dispersion obtained according to a) was coated in a conventional manner onto a commercially available ceramic flow substrate with a volume of 0.5 L and a cell number of 62 cells per square centimeter with a wall thickness of 0.17 mm over its entire length, with a washcoat loading of 360 g/L. The powder thus obtained was dried at 90° C. and then calcined at 600° C. for 2 hours. The catalyst VK10 thus obtained is in the fresh state and is therefore referred to hereinafter as VK10f. c) The VK10a obtained according to b) was subjected to hydrothermal aging for 48 hours at 700° C. in a gas atmosphere (10% O.sub.2, 10% H.sub.2O, remainder N.sub.2). The catalyst VK10 is then in the aged state and is referred to hereinafter as VK10a.

(20) Table 1 summarizes the compositions of the catalysts of the examples mentioned. The composition of the catalyst according to the invention is not limited to explicitly shown examples.

(21) TABLE-US-00001 TABLE 1 Compositions of the Catalysts of the Examples Composition V.sub.2O.sub.5 WO.sub.3 CeO.sub.2 Sb.sub.2O.sub.5 SiO.sub.2 TiO.sub.2 Example (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) K1 3.75 1.00 2.00 2.75 4.50 86.00 VK1 3.75 1.00 4.75 90.50 VK2 3.75 1.00 2.00 4.65 88.60 VK3 3.75 1.00 2.75 4.60 87.90 VK4 3.75 2.00 2.75 4.60 86.90 VK5 3.75 1.00 2.00 2.75 90.50 VK6 3.75 0.50 2.00 2.75 4.55 86.45 VK7 3.75 2.00 2.00 2.75 4.47 85.03 VK8 3.75 1.00 4.00 2.75 4.43 84.07 VK9 3.75 1.00 2.00 4.00 4.46 84.79 VK10 3.75 1.00 2.00 7.00 4.31 81.94

(22) Nitrogen oxide conversion assay as a measure of SCR activity: The NO conversions of the catalysts or comparative catalysts prepared according to the examples and comparative examples described above were determined in a quartz glass reactor. Drill cores with L=3″ and D=1″ were tested between 200 and 400° C. under steady-state conditions. Testing was carried out in a laboratory model gas system under the following conditions.

(23) TABLE-US-00002 Composition of the model gas Standard SCR Fast SCR Reaction Reaction NO.sub.x [vol. ppm]: 1,000 1,000 NO.sub.2/NO.sub.x [%] 0 75 NH.sub.3 [vol. ppm]: 1,100 1,350 O.sub.2 [vol %]: 10 10 H.sub.2O [vol %] 5 5 N.sub.2: Remainder Remainder General test conditions Space velocity [h.sup.−1]: 60.000 Temperature [° C.]: 200; 250; 300; 350; 400 Conditioning before beginning Model gas atmosphere; 550° C.; the measurement: several minutes

(24) During the measurement, the nitrogen oxide concentrations of the model gas after flowing through the catalyst were recorded using a suitable analysis method. From the known, dosed nitrogen oxide contents that were verified during conditioning at the beginning of the respective test flow with a pre-catalyst exhaust gas analysis, and the nitrogen oxide conversion contents measured after flowing through the catalyst, the nitrogen oxide conversion, relative to the ratio of NH.sub.3 to NO, over the catalyst was calculated for each temperature measuring point as follows:

(25) $U_{{\mathrm{NO}}_x}\left[\%\right]=\left(1-\frac{C_{\mathrm{output}}\left({\mathrm{NO}}_x\right)}{C_{\mathrm{input}}\left({\mathrm{NO}}_x\right)}\right)\times 100\mathrm{with}{C}_{\mathrm{input}/\mathrm{output}}\left({\mathrm{NO}}_x\right)=C_{\mathrm{input}/\mathrm{output}}\left(\mathrm{NO}\right)+C_{\mathrm{input}/\mathrm{output}}\left({\mathrm{NO}}_2\right)+C_{\mathrm{input}/\mathrm{output}}\left(N_{2}O\right)$

(26) The resulting nitrogen oxide conversion values U.sub.NOx [%] were plotted as a function of the temperature measured before to the catalyst, in order to evaluate the SCR activity of the investigated materials.

(27) Table 2 shows the NOx conversion in the standard SCR reaction for the examples described above.

(28) TABLE-US-00003 TABLE 2 NOx Conversion in the Standard SCR Reaction Nitrogen oxide conversion (%) in standard SCR reaction Fresh After hydrothermal aging 48 h 700° C. 400° C. 350° C. 300° C. 250° C. 200° C. 400° C. 350° C. 300° C. 250° C. 200° C. K1 99.09 99.25 98.74 95.00 67.11 94.36 95.16 93.19 79.03 33.58 VK1 98.42 98.39 96.85 87.75 47.47 0.41 3.41 2.77 1.84 0.85 VK2 98.40 98.27 96.54 86.64 44.99 7.47 8.67 8.23 5.68 2.22 VK3 99.08 99.28 98.80 95.36 68.97 9.69 13.86 11.05 6.15 2.17 VK4 98.79 98.98 98.38 93.78 57.62 96.43 97.22 95.81 85.66 40.74 VK5 99.11 99.32 98.65 93.51 57.88 4.60 6.32 6.35 4.85 2.31 VK6 98.90 99.05 98.56 94.25 60.28 96.59 97.52 95.79 82.79 35.31 VK7 99.29 99.48 99.05 96.17 71.64 94.82 95.71 92.05 70.23 26.41 VK8 99.02 99.22 98.61 94.22 62.04 90.26 90.78 86.14 62.87 21.64 VK9 99.23 99.43 99.06 95.56 67.52 93.76 94.33 91.63 75.27 29.59 VK10 99.03 99.37 98.94 95.39 68.12 93.45 94.47 91.27 70.35 24.61

(29) The results of the standard SCR reaction of the fresh catalysts are shown in FIG. 1.

(30) The results of the standard SCR reaction of the aged catalysts are shown in FIG. 2.

(31) Table 3 shows the NOx conversion in the fast SCR reaction for the examples described above.

(32) TABLE-US-00004 TABLE 3 NOx Conversion in the Fast SCR Reaction Nitrogen oxide conversion (%) in fast SCR reaction Fresh After hydrothermal aging 48 h 700° C. 400° C. 350° C. 300° C. 250° C. 200° C. 400° C. 350° C. 300° C. 250° C. 200° C. K1 99.39 94.47 75.07 63.10 62.19 96.39 91.06 69.34 56.36 55.76 VK1 97.60 80.80 61.14 56.95 51.08 18.41 22.47 22.35 19.95 12.24 VK2 98.82 91.34 69.93 59.55 53.20 35.88 38.44 38.66 33.25 19.30 VK3 97.52 86.89 65.80 61.71 61.98 33.83 34.88 33.57 29.34 18.68 VK4 97.71 92.37 72.79 61.70 58.96 97.17 89.64 67.19 56.49 55.90 VK5 99.80 98.30 82.93 62.98 61.10 27.79 33.76 36.58 33.48 22.16 VK6 98.84 94.33 75.27 62.96 61.17 97.35 90.20 67.99 57.15 56.93 VK7 98.53 95.40 77.87 63.56 63.67 97.90 91.97 69.69 56.97 56.52 VK8 98.92 94.95 76.87 62.90 61.60 98.01 92.54 72.91 58.75 54.55 VK9 98.91 93.84 74.01 62.22 61.97 95.35 89.70 68.65 56.07 55.03 VK10 99.48 95.16 74.62 62.13 63.44 97.30 89.15 68.37 57.38 56.02

(33) The results of the fast SCR reaction of the fresh catalysts are shown in FIG. 3.

(34) The results of the fast SCR reaction of the aged catalysts are shown in FIG. 4.

(35) The influence of the WO.sub.3 content of the catalyst on the NOx conversion in the standard SCR reaction at 200° C. and in the fast SCR reaction at 300° C. in the fresh and aged states is shown in Table 4. The quantities of V.sub.2O.sub.5, CeO.sub.2, and Sb.sub.2O.sub.5 were kept constant at 3.75 wt %, 2.00 wt %, or 2.75 wt %, while the WO.sub.3 content was varied from 0.00 wt % (VK4) to 0.50 wt % (VK6), 1.00 wt % (K1), and 2.00 wt % (VK7).

(36) TABLE-US-00005 TABLE 4 Influence of the WO.sub.3 Content on the NOx Conversion Influence of the WO.sub.3 content on the NOx conversion In the standard SCR In the fast SCR WO.sub.3 content reaction at 200° C. reaction at 300° C. [wt %] fresh aged fresh aged 0 57.6 40.7 72.8 67.2 0.5 60.3 35.3 75.3 68.0 1 67.1 33.6 75.1 69.3 2 71.6 26.4 77.9 69.7

(37) The results of the influence of the WO.sub.3 content are shown in FIG. 5.

(38) The influence of the CeO.sub.2 content of the catalyst on the NOx conversion in the standard SCR reaction at 200° C. and in the fast SCR reaction at 300° C. in the fresh and aged states is shown in Table 5. The quantities of V.sub.2O.sub.5, WO.sub.3, and Sb.sub.2O.sub.5 were kept constant at 3.75 wt %, 1.00 wt %, or 2.75 wt %, while the CeO.sub.2 content was varied from 0.00 wt % (VK3) to 2.00 wt % (K1) and 2.00 wt % (K7).

(39) TABLE-US-00006 TABLE 5 Influence of CeO.sub.2 Content on the NOx Conversion Influence of Sb.sub.2O.sub.5 content on the NOx conversion In the standard SCR In the fast SCR CeO.sub.2 content reaction at 200° C. reaction at 300° C. [wt %] fresh aged fresh aged 0 69.0 2.2 65.8 33.6 2 67.1 33.6 75.1 69.3 4 62.0 21.6 76.9 72.9

(40) The results of the influence of the CeO.sub.2 content are shown in FIG. 6.

(41) The influence of the Sb.sub.2O.sub.5 content of the catalyst on the NOx conversion in the standard SCR reaction at 200° C. and in the fast SCR reaction at 300° C. in the fresh and aged states is shown in Table 6. The quantities of V.sub.2O.sub.5, WO.sub.3, and CeO.sub.2 were kept constant at 3.75 wt %, 1.00 wt %, or 2.00 wt %, while the Sb.sub.2O.sub.5 content was varied from 0.00 wt % (VK2) to 2.75 wt % (K1), 4.00 wt % (VK9), and 7.00 wt % (VK10).

(42) TABLE-US-00007 TABLE 6 Influence of Sb.sub.2O.sub.5 Content on the NOx Conversion Influence of Sb.sub.2O.sub.5 content on the NOx conversion In the standard SCR In the fast SCR Sb.sub.2O.sub.5 content reaction, at 200° C. reaction at 300° C. [wt %] fresh aged fresh aged 0 45.0 2.2 69.9 38.7 2.75 67.1 33.6 75.1 69.3 4 67.5 29.6 74.0 68.6 7 68.5 24.6 74.6 68.4

(43) The results of the influence of the Sb.sub.2O.sub.5 content are shown in FIG. 7.