A sulfur-resistant water-based Mn-based low-temperature denitrification catalyst, its preparation method and application

Abstract

This invention provides a sulfur-resistant Mn-based low-temperature denitrification catalyst, its preparation method, and its application. The preparation method includes the following steps: adding a TiO2 support, a manganese salt solution, a cobalt salt, and a cerium salt into a ball mill jar, wherein the molar ratio of manganese salt, cobalt salt, cerium salt, and TiO2 satisfies 10:5:5:100; adding 2mm to 10mm zirconia balls to the ball mill jar, with a ball-to-material ratio of 10-15:1; ball milling at 180r / min to 580r / min for 1-3 hours to obtain a ball-milled mixture; placing the ball-milled mixture in a tube furnace, heating to 450-550℃, and calcining for 2-5 hours to obtain a 5Ce-5Co-10Mn / TiO2 catalyst. Using the technical solution of this invention, a green and efficient Mn-based low-temperature denitrification catalyst with excellent sulfur-resistant properties can be prepared.

Description

Technical Field

[0001] This invention relates to the field of denitrification catalyst technology, and in particular to a sulfur-resistant water-based Mn-based low-temperature denitrification catalyst, its preparation method, and its application. Background Technology

[0002] Waste-to-energy incineration has become the optimal option for treating municipal waste, but this process generates large amounts of harmful nitrogen oxides (NOx). x NO x It can cause serious harm to the natural environment and human health. Currently, the main method for controlling NO is through selective catalytic reduction (NH3-SCR) of NH3. x The process converts the nitrogen to nitrogen (N2). Catalysts are crucial in this technology, with Mn-based catalysts attracting significant attention due to their excellent low-temperature activity and inherent environmental friendliness. However, toxic substances generated on the catalyst surface under low-temperature conditions cannot be decomposed, thus depositing on the catalyst surface, clogging the catalyst channels and covering the active centers, leading to poisoning and deactivation of low-temperature Mn-based catalysts. To address the sulfur poisoning problem, strategies such as elemental doping, improved supports, and structural control have been employed. It has also been found that the physicochemical properties of catalysts largely depend on the preparation method. However, the current preparation processes of most Mn-based catalysts not only generate large amounts of waste liquid but also make large-scale catalyst production difficult, thus limiting their practical application. Summary of the Invention

[0003] To address the above technical problems, this invention discloses a sulfur-resistant Mn-based low-temperature denitrification catalyst, its preparation method, and its application. The high-energy ball milling method, the most commonly used mechanochemical method, is selected to achieve green and efficient catalyst preparation. Furthermore, this Mn-based catalyst can achieve efficient denitrification at a low temperature of 180℃ under sulfur-containing water conditions, and has high practical application value.

[0004] The technical solution adopted by this invention is as follows:

[0005] A method for preparing a sulfur-resistant, water-based Mn-based low-temperature denitration catalyst includes the following steps:

[0006] Step S1: Add TiO2 support, manganese salt solution, cobalt salt, and cerium salt into a ball mill jar, wherein the molar amounts of manganese salt, cobalt salt, cerium salt, and TiO2 satisfy the ratio of 10:5:5:100.

[0007] Step S2: Add 2mm to 10mm zirconia balls to the ball mill jar, with a ball-to-material ratio of 10-15:1; ball mill at a speed of 180r / min to 580r / min for 1-3 hours to obtain a ball-milled mixture;

[0008] Step S3: The ball-milled mixture is placed in a tube furnace and heated to 450-550℃ and calcined for 2-5 hours to obtain the 5Ce-5Co-10Mn / TiO2 catalyst.

[0009] Researchers generally consider ball milling to be a simple physical mixing process. However, ball milling is divided into dry milling and wet milling. Wet milling, on the other hand, uses the high-energy ball milling produced by a planetary ball mill to induce chemical reactions in substances, thus exhibiting better results than dry milling.

[0010] This technical solution utilizes mechanical energy to induce chemical reactions between precursors to prepare catalysts. This not only increases the specific surface area of ​​the catalyst, exposing more active sites, but also improves the dispersion of supported or doped metals, enhancing electron transfer and synergistic effects between metal atoms. This significantly improves the catalytic performance of the catalyst, resulting in a catalyst with excellent sulfur and water stability. Even under conditions containing water and sulfur, it can achieve NO concentrations of over 85% within a temperature range of 170–260℃. x The conversion rate is high; moreover, the preparation process is green, environmentally friendly, and efficient. As a further improvement of the present invention, in step S2, the ball-milled mixture and zirconia balls are separated; in step S3, the ball-milled mixture is dried at 90-110°C before calcination.

[0011] As a further improvement of the present invention, in step S3, the manganese salt, cobalt salt, and cerium salt are manganese nitrate, cobalt nitrate, and cerium nitrate, respectively.

[0012] As a further improvement of the present invention, in step S2, the ball-to-material ratio is 10:1.

[0013] As a further improvement of the present invention, in step S2, the ball milling speed is 380 r / min.

[0014] As a further improvement of the present invention, in step S2, the ball milling time is 2 hours.

[0015] As a further improvement of the present invention, in step S2, the diameter of the zirconia sphere is 6 mm.

[0016] As a further improvement of the present invention, in step S3, the heating rate is 5°C / min, the calcination temperature is 500°C, and the calcination time is 3 hours.

[0017] The present invention also discloses a sulfur-resistant water-based Mn-based low-temperature denitrification catalyst, which is prepared by the preparation method of Mn-based low-temperature denitrification catalyst described in any one of the above claims.

[0018] This invention also discloses the application of the sulfur-resistant, water-based Mn-based low-temperature denitrification catalyst described above, which is used in the end-of-pipe flue gas treatment of waste incineration power generation. The end-of-pipe flue gas from waste incineration power generation contains a large amount of water vapor. The catalyst using the technical solution of this invention can remove NO at low temperatures and in a water- and sulfur-containing environment. x It is efficiently converted into N2.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The technical solution of this invention uses a manganese source solution to achieve wet milling during the preparation process, and employs a suitable ball milling process. The resulting catalyst has a high specific surface area and highly dispersed active centers, as well as excellent redox properties and acidity, which greatly improves the catalyst's resistance to sulfur water and the reaction temperature window. Moreover, Mn-based catalysts can be prepared without adding additional solutions. In addition, this method is simple, efficient, easy to scale up, and does not cause secondary pollution to the environment, meeting the requirements of green and sustainable development. It has good practical application value and broad industrial application prospects. Attached Figure Description

[0021] Figure 1 The images show XRD patterns of different metal catalysts supported in embodiments of the present invention.

[0022] Figure 2 This is a TEM-Mapping image of the Ce-5Co-10Mn / TiO2 catalyst in Example 5 of the present invention.

[0023] Figure 3 The image shows the H2-TPR diagrams of different metal catalysts supported in embodiments of the present invention.

[0024] Figure 4 The image shows the NH3-TPD diagrams of different metal catalysts supported in the embodiments of the present invention.

[0025] Figure 5 This is an O2-TPD diagram of different metal catalysts supported in an embodiment of the present invention.

[0026] Figure 6 The XRD patterns of catalysts with different metals loaded using the equal-volume impregnation method are shown in the comparative examples of this invention.

[0027] Figure 7 NO from 5Ce-5Co-10Mn / TiO2 catalysts prepared under different ball-to-material ratios in embodiments of the present invention. x Conversion rate.

[0028] Figure 8 NO from 5Ce-5Co-10Mn / TiO2 catalysts prepared at different ball milling speeds in embodiments of the present invention. x Conversion rate.

[0029] Figure 9 NO content of 5Ce-5Co-10Mn / TiO2 catalysts prepared under different ball milling times in embodiments of the present invention. x Conversion rate.

[0030] Figure 10 NO content of 5Ce-5Co-10Mn / TiO2 catalysts prepared under different grinding ball diameters in this embodiment of the invention. x Conversion rate. Detailed Implementation

[0031] The preferred embodiments of the present invention will be described in further detail below.

[0032] A method for preparing a sulfur-resistant, water-based Mn-based low-temperature denitration catalyst, characterized by the following specific steps:

[0033] (1) Add the corresponding mass of TiO2 support, manganese nitrate solution, cobalt nitrate and cerium nitrate together into a ball mill jar. The optimal loading ratio of the catalyst is 5Ce-5Co-10Mn / TiO2. The loading amount is calculated according to the mass fraction ratio of active metal to support. For example, when the mass fraction of Mn loading is 10%, it is expressed as 10Mn / TiO2.

[0034] (2) Add the appropriate weight of zirconia balls (2mm to 10mm) according to the designed ball-to-material ratio (10:1 to 15:1), then fix it on the planetary ball mill, set the required rotation speed (180r / min to 580r / min) and ball milling time (1h to 3h), and use ethanol to separate the sample from the zirconia balls after ball milling.

[0035] (3) The obtained sample was placed in an oven and dried at 100°C for 12 hours, then placed in a tube furnace and heated to 500°C at 5°C / min for 3 hours to obtain the 5Ce-5Co-10Mn / TiO2 catalyst.

[0036] Using this technical solution, the 5Ce-5Co-10Mn / TiO2 catalyst obtained by ball milling is used for NO removal in NH3-SCR. x At 40000h -1 Under conditions of space velocity, 5 vol% H2O, and 50 ppm SO2, NO concentrations of over 75% can be achieved within a temperature range of 170–260 °C. x Conversion rate.

[0037] The following description uses specific examples to illustrate the point.

[0038] Example 1

[0039] The preparation method of the sulfur-resistant water-based Mn-based low-temperature denitration catalyst 5Ce-5Co-10Mn / TiO2 includes:

[0040] 5 g of TiO2 support, 3.26 g of manganese nitrate solution (50% by mass), 1.24 g of cobalt nitrate, and 0.78 g of cerium nitrate were added to a ball mill jar. Zirconia balls of 6 mm in diameter were added at a ball-to-material ratio of 10:1. The jar was then fixed in a planetary ball mill and milled for 2 hours at 380 r / min. After milling, the sample was separated from the zirconia balls using ethanol. Finally, the obtained sample was dried in an oven at 100 °C for 12 hours, then placed in a tube furnace and calcined at 5 °C / min to 500 °C for 3 hours to obtain the 5Ce-5Co-10Mn / TiO2 catalyst.

[0041] Comparative Example 1

[0042] Based on Example 1, the difference in this comparative example is that cerium nitrate was not added, and a 5Co-10Mn / TiO2 catalyst was prepared.

[0043] Comparative Example 2

[0044] Based on Example 1, the difference in this comparative example is that cerium nitrate and cobalt nitrate were not added, and a 5Co-10Mn / TiO2 catalyst was prepared.

[0045] The catalysts of Example 1, Comparative Example 1 and Comparative Example 2 were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and corresponding elemental surface scans, as well as H2 temperature-programmed reduction (H2-TPR), ammonia temperature-programmed desorption (NH3-TPD) and oxygen temperature-programmed desorption (O2-TPD).

[0046] Figure 1 These are the XRD patterns of catalysts supported on different metals. It can be observed that all catalysts only have diffraction peaks belonging to TiO2, and no characteristic peaks belonging to Ce, Co, and Mn species were observed. This indicates that the above three metals did not undergo severe agglomeration on TiO2 to form metal oxides, thus exhibiting high dispersibility.

[0047] The metal dispersion on TiO2 was further verified by TEM-Mapping, and the results are as follows: Figure 2 As shown, Ce, Co and Mn are dispersed very evenly on TiO2, resulting in strong interactions between the metal active sites.

[0048] H2-TPR diagrams of different metal catalysts are shown below Figure 3As shown, the addition of Ce and Co enhances the redox properties of the 10Mn / TiO2 catalyst.

[0049] Figures of NH3-TPD and O2-TPD for different metal catalysts are shown below. Figure 4 and Figure 5 As shown, the addition of Ce and Co enhances the acidity and reactive oxygen species of the 10Mn / TiO2 catalyst.

[0050] Comparative Example 3

[0051] A 5Ce-5Co-10Mn / TiO2 catalyst was prepared using the existing equal-volume impregnation method. This catalyst was compared with the catalyst in Example 1 using XRD. Figure 6 As shown, the XRD diffraction peaks of the catalyst prepared by the impregnation method show obvious characteristic peaks of manganese oxide, cobalt oxide and cerium oxide, while the XRD of the catalyst prepared by the high-energy ball milling method only shows characteristic peaks of TiO2. It can be seen that the microstructure of the catalyst obtained in this comparative example is different from that of the example.

[0052] The catalyst of Comparative Example 3 was subjected to sulfur- and water-containing conditions to react with NO. x The removal efficiency test results showed that the highest conversion rate at 240℃ and in sulfur-containing water was only about 65%.

[0053] Example 2

[0054] The preparation method of the sulfur-resistant water-based Mn-based low-temperature denitration catalyst 5Ce-5Co-10Mn / TiO2 includes:

[0055] 5 g of TiO2 support, 3.26 g of manganese nitrate solution, 1.24 g of cobalt nitrate, and 0.78 g of cerium nitrate were added to a ball mill jar. Zirconia balls (6 mm) of the appropriate weight were added according to the designed ball-to-material ratio (5:1, 10:1, 15:1). The jar was then fixed on a planetary ball mill and milled for 2 hours at a speed of 580 r / min. After milling, the sample was separated from the zirconia balls using ethanol. Finally, the obtained sample was dried in an oven at 100 °C for 12 hours, then placed in a tube furnace and calcined at 500 °C at a rate of 5 °C / min for 3 hours to obtain 5Ce-5Co-10Mn / TiO2 catalysts milled using different ball-to-material ratios.

[0056] The catalyst activity of the 5Ce-5Co-10Mn / TiO2 catalysts ball-milled with different ball-to-material ratios was tested, including in a fixed-bed quartz reactor (6 mm inner diameter) containing 0.15 mL of GHSV (40000 h⁻¹). -1Catalyst (40-60 mesh). The simulated flue gas contained 400ppm NO, 400ppm NH3, 6% O2, 50ppm SO2, 5vol.% H2O, and Ar as the balance gas, with a total flow rate of 100mL / min.

[0057] Figure 7 The effects of 5Ce-5Co-10Mn / TiO2 catalysts prepared under different ball-to-material ratios on NO x The removal effect was observed. Results showed that catalysts prepared at ball-to-material ratios of 10:1 and 15:1 exhibited better NO removal performance. x The removal effect is quite good, especially the catalyst prepared under the condition of ball-to-material ratio of 10:1, which has the best denitrification effect. This is because even in the presence of SO2 / H2O, the catalyst exhibits NO removal efficiency within the temperature range of 160℃~300℃. x The conversion rate still exceeds 80%, which is higher than that of catalysts prepared under the other two ball-to-material ratios.

[0058] Example 3

[0059] The preparation method of the sulfur-resistant water-based Mn-based low-temperature denitration catalyst 5Ce-5Co-10Mn / TiO2 includes:

[0060] 5 g of TiO2 support, 3.26 g of manganese nitrate solution, 1.24 g of cobalt nitrate, and 0.78 g of cerium nitrate were added to a ball mill jar. Zirconia balls (6 mm) of the appropriate weight were added according to the designed ball-to-material ratio (10:1). The jar was then fixed on a planetary ball mill and milled for 2 hours. Experiments were conducted at speeds of 180 r / min, 380 r / min, and 580 r / min. After milling, the sample was separated from the zirconia balls using ethanol. Finally, the obtained sample was dried in an oven at 100 °C for 12 hours, then placed in a tube furnace and calcined at 5 °C / min to 500 °C for 3 hours to obtain 5Ce-5Co-10Mn / TiO2 catalysts with different milling speeds.

[0061] The catalyst activity of the above-mentioned 5Ce-5Co-10Mn / TiO2 catalysts with different ball milling speeds was tested. The steps included: conducting the test in a fixed-bed quartz reactor (6 mm inner diameter), the reactor being loaded with 0.15 mL of GHSV = 40000 h⁻¹. -1 Catalyst (40-60 mesh). The simulated flue gas contained 400ppm NO, 400ppm NH3, 6% O2, 50ppm SO2, 5vol.% H2O, and Ar as the balance gas, with a total flow rate of 100mL / min.

[0062] Figure 8 The effects of 5Ce-5Co-10Mn / TiO2 catalysts prepared under different ball milling speeds on NOx The removal effect of the catalyst was observed. Results showed that when the ball milling speed was 380 r / min, the NO removal efficiency of the catalyst was significantly improved. x The conversion rate reached as high as 95% within a wider temperature window (170℃~260℃), indicating that the ball milling speed has a significant impact on the catalyst's resistance to SO2 / H2O.

[0063] Example 4

[0064] The preparation method of the sulfur-resistant water-based Mn-based low-temperature denitration catalyst 5Ce-5Co-10Mn / TiO2 includes:

[0065] 5 g of TiO2 support, 3.26 g of manganese nitrate solution, 1.24 g of cobalt nitrate, and 0.78 g of cerium nitrate were added to a ball mill jar. Zirconia balls (6 mm) of the appropriate weight were added according to the designed ball-to-material ratio (10:1). The jar was then fixed on a planetary ball mill and milled for 1 h, 2 h, and 3 h at a speed of 380 r / min. After milling, the sample was separated from the zirconia balls using ethanol. Finally, the obtained sample was dried in an oven at 100 °C for 12 h, then placed in a tube furnace and calcined at 5 °C / min to 500 °C for 3 h to obtain 5Ce-5Co-10Mn / TiO2 catalysts with different milling times.

[0066] The catalyst activity of the above-mentioned 5Ce-5Co-10Mn / TiO2 catalysts with different ball milling times was tested. The steps included: conducting the test in a fixed-bed quartz reactor (6 mm inner diameter), the reactor being packed with 0.15 mL of GHSV (40000 h⁻¹). -1 Catalyst (40-60 mesh). The simulated flue gas contained 400ppm NO, 400ppm NH3, 6% O2, 50ppm SO2, 5vol.% H2O, and Ar as the balance gas, with a total flow rate of 100mL / min.

[0067] Figure 9 The effects of 5Ce-5Co-10Mn / TiO2 catalysts prepared under different ball milling time conditions on NO x The denitrification effect was observed. The results showed that the catalyst exhibited the best denitrification performance when the ball milling time was 2 hours, indicating that the ball milling time has a certain influence on the catalyst's performance.

[0068] Example 5

[0069] The preparation method of the sulfur-resistant water-based Mn-based low-temperature denitration catalyst 5Ce-5Co-10Mn / TiO2 includes:

[0070] 5 g of TiO2 support, 3.26 g of manganese nitrate solution, 1.24 g of cobalt nitrate, and 0.78 g of cerium nitrate were added to a ball mill jar. Zirconia balls (2 mm, 6 mm, and 10 mm) of appropriate weight were added according to the designed ball-to-material ratio (10:1). The jar was then fixed on a planetary ball mill and milled for 2 hours at 380 r / min. After milling, the sample was separated from the zirconia balls using ethanol. Finally, the obtained sample was placed in an oven and dried at 100 °C for 12 hours, then placed in a tube furnace and calcined at 5 °C / min to 500 °C for 3 hours to obtain 5Ce-5Co-10Mn / TiO2 catalysts with different milling ball diameters.

[0071] Catalytic activity tests were conducted on catalysts obtained using different grinding ball diameters in a fixed-bed quartz reactor (6 mm inner diameter) containing 0.15 mL of GHSV (40000 h⁻¹). -1 Catalyst (40-60 mesh). The simulated flue gas contained 400ppm NO, 400ppm NH3, 6% O2, 50ppm SO2, 5vol.% H2O, and Ar as the balance gas, with a total flow rate of 100mL / min.

[0072] Figure 10 The effects of 5Ce-5Co-10Mn / TiO2 catalysts prepared under different grinding ball diameter conditions on NO x The removal effect of the catalyst was observed. Results showed that when the grinding ball diameter was 6 mm, the NO removal efficiency was significantly improved. x The conversion rate is as high as 95% within a temperature window of 170℃ to 260℃.

[0073] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. The application of a sulfur-resistant water-based Mn-based low-temperature denitrification catalyst, characterized in that: Its application in end-of-pipe flue gas treatment for waste incineration power generation, the preparation method of the sulfur-resistant water-based Mn-based low-temperature denitrification catalyst includes the following steps: Step S1: Add TiO2 support, manganese salt solution, cobalt salt, and cerium salt into a ball mill jar, wherein the molar amounts of manganese salt, cobalt salt, cerium salt, and TiO2 satisfy the ratio of 10:5:5:

100. Step S2: Add zirconia balls with a diameter of 6 mm to 10 mm to the ball mill jar, with a ball-to-material ratio of 10-15:1; ball mill at a speed of 180 r / min to 580 r / min for 2-3 hours to obtain a ball-milled mixture; separate the ball-milled mixture from the zirconia balls to obtain the sample product; Step S3: Dry the sample product at 90-110℃, then place it in a tube furnace and heat it to 450-550℃ and calcine it for 2-5 hours to obtain the 5Ce-5Co-10Mn / TiO2 catalyst.

2. The application of the sulfur-resistant water-based Mn-based low-temperature denitrification catalyst according to claim 1, characterized in that: In step S3, the manganese salt, cobalt salt, and cerium salt are manganese nitrate, cobalt nitrate, and cerium nitrate, respectively.

3. The application of the sulfur-resistant water-based Mn-based low-temperature denitrification catalyst according to claim 1, characterized in that: In step S2, the ball-to-material ratio is 10:

1.

4. The application of the sulfur-resistant water-based Mn-based low-temperature denitrification catalyst according to claim 3, characterized in that: The ball milling time in step S2 is 2 hours.

5. The application of the sulfur-resistant water-based Mn-based low-temperature denitrification catalyst according to claim 4, characterized in that: In step S2, the diameter of the zirconia sphere is 6 mm.

6. The application of the sulfur-resistant water-based Mn-based low-temperature denitrification catalyst according to claim 1, characterized in that: In step S3, the heating rate is 5℃ / min; the calcination temperature is 500℃; and the calcination time is 3h.

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