A sulfur-resistant Ce-Mn-Zr catalyst and its preparation method and application

Abstract

The present invention discloses a sulfur-resistant Ce-Mn-Zr catalyst and its preparation method and application. The Ce-Mn-Zr catalyst contains transition metals ZrO2, MnO2 and CeO2. The present invention obtains a Ce-Mn-Zr catalyst by doping Zr, and utilizes the stabilizing effect of Zr on the size of the catalyst and the effect of inhibiting clustering to increase the dispersibility of the catalyst active sites, thereby exposing more active sites to delay the poisoning process of the catalyst. In addition, the Ce-Mn-Zr catalyst of the present invention has high sulfur resistance and can perform SCR denitrification for a long time in the presence of SO2.

Description

Technical Field

[0001] The invention belongs to the technical field of denitration catalytic materials, and in particular relates to a sulfur-resistant Ce-Mn-Zr catalyst and a preparation method and application thereof. Background Art

[0002] In non-electrical industries, such as steel mills, waste incinerators, combustion boilers, etc., the presence of SO2 is usually the main cause of catalyst deactivation at <200℃. MnO x Often used as a low-temperature catalyst for NH3-SCR reaction, CeO2 is used as MnO due to its strong oxygen storage capacity and excellent redox properties. X modifier to improve its denitrification performance, but CeO2 is easily affected by SO2, which limits its application. Improving the sulfur resistance of Ce-Mn catalysts is the current key research direction.

[0003] The low-temperature denitrification catalyst with high sulfur resistance mainly improves the redox performance of Ce-Mn catalyst by element doping, surface acidity or the introduction of elements that can be preferentially sulfurized by sulfur dioxide as sacrificial agents to protect the active sites on the catalyst surface. The advantage of the catalyst prepared by this method is that it can significantly improve its denitrification performance in a short period of time, while long-term sulfurization will cause the exposed active sites of the catalyst to be greatly reduced and deactivated. However, if the sulfur resistance of the catalyst needs to be further improved for a long time and stably, it is necessary to expose more active sites, which can be further achieved by controlling the dispersion state of the active sites. Summary of the invention

[0004] The object of the present invention is to provide a sulfur-resistant Ce-Mn-Zr catalyst and a preparation method and application thereof in view of the deficiencies of the above-mentioned prior art.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: A sulfur-resistant Ce-Mn-Zr catalyst comprises transition metals such as ZrO2, MnO2 and CeO2.

[0006] The present invention obtains a Ce-Mn-Zr catalyst by doping Zr, and utilizes the stabilizing effect of Zr on the size of the catalyst and the effect of inhibiting clustering to increase the dispersion of the catalyst active sites, thereby exposing more active sites to delay the poisoning process of the catalyst. In addition, the Ce-Mn-Zr catalyst of the present invention has high sulfur resistance and can perform SCR denitrification for a long time in the presence of SO2.

[0007] The present invention claims a method for preparing the sulfur-resistant Ce-Mn-Zr catalyst, comprising the following steps:

[0008] (1) dissolving a cerium source and a manganese source in water and mixing them evenly to obtain a mixed solution;

[0009] (2) adding a zirconium source into the mixed solution and stirring the mixture evenly, and then subjecting the mixture to a hydrothermal reaction to obtain the sulfur-resistant Ce-Mn-Zr catalyst.

[0010] The invention obtains the catalyst by subjecting a cerium source, a manganese source and a zirconium source to a simple hydrothermal reaction. The preparation method is simple and suitable for industrial large-scale production.

[0011] As a preferred embodiment of the present invention, in the step (1), the molar ratio of the cerium source to the manganese source is 1:1-10.

[0012] The present invention optimizes the denitration performance and sulfur resistance of the sulfur-resistant Ce-Mn-Zr catalyst by regulating the ratio of the cerium source and the manganese source. The ratio of the cerium source and the manganese source within the above-mentioned ratio range is conducive to the formation of an amorphous structure of the Ce-Mn-Zr catalyst, thereby increasing the specific surface area and improving the denitration performance and sulfur resistance of the material.

[0013] As a preferred embodiment of the present invention, in the step (1), the molar ratio of the cerium source to the manganese source is 1:3-5; more preferably, the molar ratio of the cerium source to the manganese source is 1:4.

[0014] The present invention has found through a large number of experiments that when the molar ratio of the cerium source to the manganese source is 1:4, the denitration performance and sulfur resistance of the sulfur-resistant Ce-Mn-Zr catalyst are optimal.

[0015] As a preferred embodiment of the present invention, the mass percentage of the zirconium source is 0.7%-5% based on the total mass of the cerium source and the manganese source.

[0016] The addition of zirconium source can improve the dispersion of the material and reduce the agglomeration of species on the catalyst surface. However, when the mass percentage of zirconium source is greater than 5%, the denitration performance of the catalyst decreases.

[0017] As a preferred embodiment of the present invention, the mass percentage of the zirconium source is 1-5% based on the total mass of the cerium source and the manganese source; more preferably, the mass percentage of the zirconium source is 3% based on the total mass of the cerium source and the manganese source.

[0018] As a preferred embodiment of the present invention, in the step (2), the stirring time is 1-3 hours.

[0019] As a preferred embodiment of the present invention, in step (2), the temperature of the hydrothermal reaction is 70 to 220° C., and the time of the hydrothermal reaction is 8 to 72 hours.

[0020] The present invention regulates the amorphous state of the catalyst by regulating the hydrothermal temperature and time, thereby optimizing the denitration performance and sulfur resistance of the catalyst. Excessively high or long hydrothermal temperature and time are not conducive to the formation of the amorphous state of the catalyst, thereby being not conducive to the improvement of the denitration performance and sulfur resistance of the catalyst.

[0021] As a preferred embodiment of the present invention, the cerium source is at least one of cerium nitrate, cerium chloride, cerium carbonate and cerium sulfate; the manganese source is potassium permanganate; and the zirconium source is at least one of zirconium nitrate, zirconium chloride, zirconium carbonate and zirconium sulfate.

[0022] The present invention also claims the use of the sulfur-resistant Ce-Mn-Zr catalyst in low-temperature flue gas denitration.

[0023] Compared with the prior art, the present invention has the following beneficial effects: the present invention obtains a Ce-Mn-Zr catalyst by doping Zr, and utilizes the stabilizing effect of Zr on the size of the catalyst and the effect of inhibiting clustering to increase the dispersion of the catalyst active sites, thereby exposing more active sites to delay the poisoning process of the catalyst. In addition, the Ce-Mn-Zr catalyst of the present invention has high sulfur resistance and can perform SCR denitrification for a long time in the presence of SO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 XRD diagrams of the catalysts prepared in Example 1 and Comparative Examples 1-2 of the present invention;

[0025] Figure 2 The denitration performance diagram of the catalyst prepared in Example 1 and Comparative Examples 1-2 of the present invention;

[0026] Figure 3 This is a graph showing the denitration stability performance of the catalysts prepared in Example 1 of the present invention and Comparative Examples 1-2. DETAILED DESCRIPTION

[0027] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0028] Example 1

[0029] The method for preparing the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment comprises the following steps:

[0030] (1) dissolving cerium nitrate and potassium permanganate in water and mixing them evenly to obtain a mixed solution; the molar ratio of cerium nitrate to potassium permanganate is 1:4;

[0031] (2) adding 3% zirconium nitrate to the total mass of cerium nitrate and potassium permanganate to the mixed solution and stirring for 2 hours until it is uniform, and then hydrothermally reacting at 120° C. for 20 hours to obtain the sulfur-resistant Ce-Mn-Zr catalyst.

[0032] Example 2

[0033] The method for preparing the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment comprises the following steps:

[0034] (1) dissolving cerium chloride and potassium permanganate in water and mixing them evenly to obtain a mixed solution; the molar ratio of cerium nitrate to potassium permanganate is 1:1;

[0035] (2) adding 0.7% zirconium chloride based on the total mass of cerium nitrate and potassium permanganate into the mixed solution and stirring for 1 hour until it is uniform, and then hydrothermally reacting at 160° C. for 8 hours to obtain the sulfur-resistant Ce-Mn-Zr catalyst.

[0036] Example 3

[0037] The method for preparing the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment comprises the following steps:

[0038] (1) dissolving cerium sulfate and potassium permanganate in water and mixing them evenly to obtain a mixed solution; the molar ratio of cerium nitrate to potassium permanganate is 1:10;

[0039] (2) adding 5% zirconium sulfate accounting for the total mass of cerium nitrate and potassium permanganate to the mixed solution and stirring for 3 hours until it is uniform, and then hydrothermally reacting at 70° C. for 72 hours to obtain the sulfur-resistant Ce-Mn-Zr catalyst.

[0040] Example 4

[0041] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (1), the molar ratio of cerium nitrate to potassium permanganate is 1:1.

[0042] Example 5

[0043] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (1), the molar ratio of cerium nitrate to potassium permanganate is 1:3.

[0044] Example 6

[0045] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (1), the molar ratio of cerium nitrate to potassium permanganate is 1:5.

[0046] Example 7

[0047] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (1), the molar ratio of cerium nitrate to potassium permanganate is 1:10.

[0048] Example 8

[0049] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (2), the mass of zirconium nitrate is 0.7% of the total mass of cerium nitrate and potassium permanganate.

[0050] Example 9

[0051] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (2), the mass of zirconium nitrate is 1% of the total mass of cerium nitrate and potassium permanganate.

[0052] Example 10

[0053] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (2), the mass of zirconium nitrate is 5% of the total mass of cerium nitrate and potassium permanganate.

[0054] Embodiment 11

[0055] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (2), the temperature of the hydrothermal reaction is 70°C.

[0056] Example 12

[0057] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (2), the temperature of the hydrothermal reaction is 180°C.

[0058] Embodiment 13

[0059] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this embodiment and that in Embodiment 1 is that in step (2), the temperature of the hydrothermal reaction is 220°C.

[0060] Comparative Example 1

[0061] The preparation method of the Ce-Mn catalyst described in this comparative example comprises the following steps:

[0062] (1) dissolving cerium nitrate and potassium permanganate in water and mixing them evenly to obtain a mixed solution; the molar ratio of cerium nitrate to potassium permanganate is 1:4;

[0063] (2) The mixed solution is subjected to a hydrothermal reaction at 120° C. for 20 h to obtain the Ce—Mn catalyst.

[0064] Comparative Example 2

[0065] The MnO x The method for preparing the catalyst comprises the following steps:

[0066] Manganese nitrate and potassium permanganate were dissolved in water and mixed evenly, and then hydrothermally reacted at 120°C for 26 hours to obtain the MnO x Catalyst: The molar ratio of manganese nitrate to potassium permanganate is 3:2.

[0067] Comparative Example 3

[0068] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this comparative example and that in Example 1 is that in step (1), the molar ratio of cerium nitrate to potassium permanganate is 1:0.5.

[0069] Comparative Example 4

[0070] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this comparative example and that in Example 1 is that in step (1), the molar ratio of cerium nitrate to potassium permanganate is 1:12.

[0071] Comparative Example 5

[0072] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst in this comparative example and that in Example 1 is that in step (2), the mass of zirconium nitrate is 0.3% of the total mass of cerium nitrate and potassium permanganate.

[0073] Comparative Example 6

[0074] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst in this comparative example and that in Example 1 is that in step (2), the mass of zirconium nitrate is 9% of the total mass of cerium nitrate and potassium permanganate.

[0075] Comparative Example 7

[0076] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this comparative example and that in Example 1 is that in step (2), the temperature of the hydrothermal reaction is 50°C.

[0077] Comparative Example 8

[0078] The only difference between the preparation method of the sulfur-resistant Ce-Mn-Zr catalyst described in this comparative example and that in Example 1 is that in step (2), the temperature of the hydrothermal reaction is 280°C.

[0079] Test Example 1

[0080] Figure 1The XRD diagrams of the catalysts prepared in Example 1 and Comparative Examples 1-2 of the present invention are shown. Figure 1 OMS-2 is the MnOx catalyst prepared in Comparative Example 2, Ce-Mn is the Ce-Mn catalyst prepared in Comparative Example 1, Ce-Mn-Zr is the Ce-Mn-Zr catalyst prepared in Example 1, KMn5O 16 (JDPDS-29-1020) is the crystal structure standard card of MnOx catalyst, and CeO2 (JDPDS-34-0394) is the standard card of CeO2. It can be seen from the figure that after adding Ce, the MnOx catalyst changes to an amorphous structure; and the Ce-Mn-Zr catalyst has no impurity peaks, indicating that the obtained Ce-Mn-Zr catalyst has a high purity.

[0081] Test Example 2

[0082] The present invention provides a test example for testing the denitration performance of a sulfur-resistant Ce-Mn-Zr catalyst, and measures the denitration performance of the catalyst at different temperatures.

[0083] Test samples: catalysts prepared in Examples and Comparative Examples.

[0084] Test conditions: The catalyst is placed in a denitration evaluation device to test its denitration catalytic performance in the range of 50-280°C. Reaction gas: 60-70ppmNO, 60ppmNH3, GHSV is 2000h -1 The test results are shown in Table 1. The reaction window temperature in Table 1 is the temperature range where the denitrification efficiency is above 80%.

[0085] Table 1

[0086]

[0087]

[0088] Figure 2 OMS-2 is the MnOx catalyst prepared in Comparative Example 2, Ce-Mn is the Ce-Mn catalyst prepared in Comparative Example 1, and Ce-Mn-Zr is the Ce-Mn-Zr catalyst prepared in Example 1. Figure 2According to the data, compared with comparative examples 2-8, the Ce-Mn-Zr catalyst prepared in the embodiment of the present invention has excellent denitration performance, wherein the Ce-Mn-Zr catalyst described in Example 1 has the best denitration performance, and the denitration efficiency at 50-220°C is above 80%. According to Examples 1, 4-7 and Comparative Examples 3-4, when the molar ratio of cerium nitrate to potassium permanganate is 1:4, the denitration performance of the Ce-Mn-Zr catalyst is the best, and the ratio of cerium nitrate to potassium permanganate is within the specified range of the present invention, and the prepared Ce-Mn-Zr catalyst has good denitration performance. According to the data of Examples 1, 8-10 and Comparative Examples 5-6, within the specified range of the present invention, the highest denitration efficiency of the Ce-Mn-Zr catalyst is as high as 100%. According to the data of Examples 1, 11-12 and Comparative Examples 7-8, it can be seen that too high and too low hydrothermal temperature are not conducive to improving the denitration performance of the Ce-Mn-Zr catalyst.

[0089] Test Example 3

[0090] The present invention discloses a test example of sulfur resistance performance test of a sulfur-resistant Ce-Mn-Zr catalyst.

[0091] Test samples: catalysts prepared in Examples and Comparative Examples.

[0092] Test conditions: Place the catalyst in a denitration evaluation device to test the stability of its denitration catalytic performance at 150°C, and test the denitration catalytic performance of the catalyst at 0h, when the temperature is just stabilized at 150°C, and at 38h. Reaction gas: 60-70ppmNO, 60ppmNH3, 60mg / m 3 SO2, GHSV is 2000h -1 .

[0093] Table 2

[0094]

[0095]

[0096] Figure 3 OMS-2 is the MnOx catalyst prepared in Comparative Example 2, Ce-Mn is the Ce-Mn catalyst prepared in Comparative Example 1, and Ce-Mn-Zr is the Ce-Mn-Zr catalyst prepared in Example 1. Figure 3 It can be seen from the data that, compared with the comparative example, the Ce-Mn-Zr catalyst prepared in the embodiment of the present invention has better sulfur resistance.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a Ce-Mn-Zr catalyst with low-temperature denitration and sulfur resistance, characterized in that: The steps include: (1) dissolving cerium nitrate and potassium permanganate in water and mixing them evenly to obtain a mixed solution; the molar ratio of the cerium nitrate to potassium permanganate is 1:4; (2) adding zirconium nitrate to the mixed solution and stirring evenly, and then subjecting the mixture to a hydrothermal reaction to obtain the Ce-Mn-Zr catalyst having low-temperature denitration and sulfur resistance; the zirconium nitrate accounts for 3% of the weight of the cerium nitrate and potassium permanganate; The temperature of the hydrothermal reaction is 70-220° C., and the time of the hydrothermal reaction is 8-72 hours; The Ce-Mn-Zr catalyst contains ZrO2, MnO2 and CeO2; and the Ce-Mn-Zr catalyst has an amorphous structure.

2. A Ce-Mn-Zr catalyst with low-temperature denitration and sulfur resistance obtained by the preparation method according to claim 1.

3. Use of the Ce-Mn-Zr catalyst with low-temperature denitration and sulfur resistance as claimed in claim 2 in low-temperature denitration of flue gas.

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