A low-temperature CO catalytic oxidation catalyst with high sulfur resistance performance, a preparation method and application thereof

Abstract

This invention discloses a low-temperature CO catalytic oxidation catalyst with high sulfur resistance, its preparation method, and its application. The catalyst support is TiLaAlO. x A composite metal oxide, wherein an active ingredient and an auxiliary metal M are loaded onto a support, the active ingredient being the noble metal Pd, and the auxiliary metal M being one or more of Co, Cr, Cu, Sn, Mo, W, Fe, Y, Ni, and Nb, with Pd loading at 0.1-4% and auxiliary metal M loading at 0.5-5%; the TiLaAlO x The molar ratio of Ti, La, and Al in the composite metal oxide is 5-15:5-15:80. The catalyst prepared by this invention is particularly suitable for the catalytic combustion of CO in steel tail gas, and it has high sulfur resistance, maintaining high activity for CO gas even in an environment of 300 ppm SO2, thus possessing significant industrial application potential and value.

Description

Technical Field

[0001] This application relates to the field of air pollution control technology, specifically to a low-temperature CO catalytic oxidation catalyst with high sulfur resistance, its preparation method, and its application. Background Technology

[0002] Catalytic oxidation completely burns toxic CO into CO2, offering advantages such as high purification efficiency, no secondary pollution, low energy consumption, and high heat release, making it considered the most effective means of CO elimination. However, catalysts are easily poisoned and deactivated in high-temperature environments or in sulfur- or chlorine-containing atmospheres. The high CO concentration in steel sintering flue gas means the heat released by catalytic combustion can raise the flue gas temperature, ensuring the required temperature for downstream SCR denitrification. Therefore, developing highly stable catalysts is a key technology for treating steel sintering gas. However, steel sintering gas contains a certain concentration of SO2, and CO catalysts are easily deactivated in sulfur-containing atmospheres, especially when the volume fraction of sulfides exceeds 5 × 10⁻⁶. -6 The activity of the catalyst will be inhibited. Sulfur-containing compounds compete with reactants for adsorption active sites during the catalytic reaction, which may cause a temporary decrease in activity, or even react with the main active species or support to form sulfites or sulfates, resulting in irreversible chemical deactivation.

[0003] Currently, numerous patents for catalysts for CO oxidation and elimination have been reported both domestically and internationally. For example, CN109092304A discloses a Pt-based catalyst prepared by a combination of microwave heating and atomic capture, which can eliminate CO at medium and low temperatures. However, its sulfur resistance is not described, and the preparation process is cumbersome and energy-intensive. CN116060036A discloses a monolithic catalyst prepared by co-supporting copper, manganese, and platinum-based elements. Although it has some sulfur resistance, it can only maintain good stability at a high temperature of 500℃, making it unsuitable for the application scenarios of steel sintering gas and large-scale industrial use. CN118142520A discloses a core-shell structure catalyst with nano-Pt, Pd, and Ru nanoparticles as the core, SnO2 as the shell, and Sn-containing metal oxide as the support. In the CO oxidation process containing 10 ppm SO2, the catalyst exhibits high catalytic activity and stability, but it is not suitable for large-scale industrial applications. Existing CO catalysts already possess very low activation temperatures, but their sulfur resistance needs improvement. Practical engineering applications require activation temperatures that are not particularly low, especially in the steel industry where flue gas temperatures are mostly above 160℃. Engineering applications place high demands on the sulfur resistance of catalysts, which is crucial for their applicability. Therefore, developing a highly efficient, sulfur-resistant, and stable low-temperature CO catalytic oxidant is of great significance for the green development of the steel industry. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems in the prior art, the purpose of this invention is to provide a low-temperature CO catalytic oxidation catalyst with high sulfur resistance, its preparation method and application.

[0005] The technical solution adopted in this invention is as follows:

[0006] The aforementioned low-temperature CO catalytic oxidation catalyst with high sulfur resistance is supported on TiLaAlO. x A composite metal oxide, wherein an active ingredient and an auxiliary metal M are loaded onto a support. The active ingredient is the noble metal Pd, and the auxiliary metal M is one or more of Co, Cr, Cu, Sn, Mo, W, Fe, Y, Ni, and Nb. The Pd loading is 0.1-4%, and the auxiliary metal M loading is 0.5-5%. The TiLaAlO x The molar ratio of Ti, La, and Al in the composite metal oxide is 5-15:5-15:80.

[0007] Furthermore, the catalyst has a Pd loading of 0.5-2% and an auxiliary metal M loading of 1-2%, and the TiLaAlO... x The molar ratio of Ti, La, and Al in the composite metal oxide is 8-12:8-12:80.

[0008] Furthermore, the auxiliary metal M is one or both of Ni and Y.

[0009] The preparation method of the low-temperature CO catalytic oxidation catalyst with high sulfur resistance includes the following steps:

[0010] S1: According to TiLaAlO x A composite metal oxide containing Ti, La, and Al in a specific molar ratio was prepared by dissolving La(NO3)3·6H2O and Al(NO3)3·9H2O together in water. A titanium isopropoxide solution diluted with ethanol was added dropwise, and the pH was adjusted to 8.0–10.0 with alkali. The mixture was stirred for 0.5–4 hours, then allowed to stand at room temperature for 10–15 hours to age. After filtration, the mixture was washed several times with deionized water and anhydrous ethanol until the filtrate was neutral. It was then dried and calcined at 300–600°C in air for 2–5 hours to obtain TiLaAlO. x Composite oxide powder;

[0011] S2: Dissolve the nitrate of metal M in deionized water, and add TiLaAlO. x The composite oxide powder was stirred in a water bath at 50-70℃ for 20-60 min, and the resulting mixture was subjected to vacuum rotary evaporation to remove excess water and obtain solid powder. The powder was dried overnight and calcined at 300-600℃ for 2-5 h to obtain the modified support TiLaAlOx-M.

[0012] S3: The noble metal is loaded using the equal volume impregnation method. The carrier powder obtained in step S2 is impregnated in the aqueous solution of the Pd precursor. The resulting mixture is stirred in a water bath at 65-85°C for 1-3 hours to allow the noble metal Pd to be fully adsorbed on the carrier surface. Then, it is filtered, dried, and calcined in air at 300-600°C for 2-5 hours to complete the preparation.

[0013] Furthermore, in steps S1, S2, or S3, the calcination temperature is 380-420℃.

[0014] Furthermore, in step S3, the temperature of the stirring reduction reaction is 65–85°C, and the reaction time is 0.5–2 h.

[0015] The application of a high-sulfur-resistant low-temperature CO catalytic oxidation catalyst in the catalytic combustion of CO involves loading the catalyst into a tubular reactor, heating it to the catalytic combustion reaction temperature, using air as a dilution gas to dilute the CO gas to form a gaseous feedstock, and then introducing it into the tubular reactor for catalytic combustion reaction.

[0016] Furthermore, the CO gas concentration in the gaseous feedstock is preferably 1000 ppm to 20000 ppm.

[0017] The concentration of SO2 in the gaseous feedstock is 0–600 ppm, with a reaction space velocity of 20,000–80,000 mL·g. -1 ·h -1 The reaction temperature for catalytic combustion is 160-250℃, preferably 200-220℃.

[0018] Furthermore, the SO2 gas concentration in the gaseous feedstock is below 300 ppm.

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

[0020] This invention uses palladium chloride (PdCl4), titanium isopropoxide (Ti(OCH(CH3)2)4), lanthanum nitrate hexahydrate (La(NO3)3·6H2O), and aluminum nitrate nonahydrate (Al(NO3)3·9H2O) as main raw materials, and employs an equal-volume impregnation method to load Pd to obtain Pd / TiLaAlO. xThe catalyst, M (where M is one or more of Co, Cr, Cu, Sn, Mo, W, Fe, Y, Ni, Nb, etc.), has a Pd loading of 0.1–4 wt% and an auxiliary metal loading of 0.5–5%. It features a simple preparation process, low catalyst cost, and high sulfur resistance for CO oxidation. When the auxiliary metal M is Ni or Y, the corresponding catalyst exhibits even better sulfur resistance and catalytic stability. The catalyst prepared by this invention is particularly suitable for the catalytic combustion of CO in steel tail gas and possesses high sulfur resistance, maintaining high activity towards CO even in a 300 ppm SO2 environment, demonstrating significant industrial application potential and value. Attached Figure Description

[0021] Figure 1 The results show the comparison of CO conversion rates of the catalysts in Examples 1-7 of this invention when catalytic combustion reaches stability at different reaction temperatures under conditions containing 300 ppm SO2 gas.

[0022] Figure 2 This is a comparison of the CO conversion rates of the catalysts in Example 1 and Comparative Examples 1-2 when they reached stable catalytic combustion at different reaction temperatures under conditions containing 300 ppm SO2 gas.

[0023] Figure 3 The stability curve of the catalyst in Example 1 under the continuous reaction of catalytic combustion of CO is shown.

[0024] Figure 4 The catalyst stability curve for Example 2 is shown in the continuous reaction of catalytic combustion of CO.

[0025] Figure 5 The catalyst stability curve for Example 5 is shown when the catalyst is applied to the continuous reaction of catalytic combustion of CO.

[0026] Figure 6 Example 3: Catalyst stability curves for continuous catalytic combustion of CO.

[0027] Figure 7 Example 4: Catalyst stability curves for continuous catalytic combustion of CO.

[0028] Figure 8 Example 6: Catalyst stability curves for continuous catalytic combustion of CO.

[0029] Figure 9 Example 7: Catalyst stability curves for continuous catalytic combustion of CO. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0031] Example 1

[0032] Step 1: Dissolve 6.4984g La(NO3)3·6H2O and 54.4576g Al(NO3)3·9H2O in 200ml of deionized water, denoted as solution A. Dissolve 5.4458g titanium isopropoxide in 6.8072g of ethanol, denoted as solution B. While vigorously stirring, simultaneously add solution B and a 1mol / L ammonia solution to solution A to adjust the pH to 9.0. Stir the mixture for 3 hours, allow it to stand at room temperature for 12 hours to age, filter, wash repeatedly with deionized water until the filtrate is neutral, dry at 110℃ for 12 hours, and calcine at 400℃ in air for 4 hours to obtain Ti. 10 La 10 Al 80 O x A composite oxide support in which the molar ratio of Ti / La / Al is 10:10:80.

[0033] Step 2: Dissolve 4 mL of chloropalladium acid solution (Pd concentration in the solution is 2.5 g / L) in 20 mL of deionized water, and add the TiLaAlO obtained in step 1. x 1.0 g of carrier powder was dispersed in a chloropalladic acid solution. The resulting mixture was stirred in a 75°C water bath for 1 h, filtered, dried at 110°C for 1 h, and calcined at 400°C for 4 h to obtain 1 wt% Pd / TiLaAlO. x catalyst.

[0034] Comparative Example 1:

[0035] 1wt% Pd / TiAlO x The catalyst preparation steps were repeated in Example 1, except that "La(NO3)3·6H2O was not added in the first step," while the other conditions remained unchanged, ultimately yielding 1wt% Pd / TiAlO. x catalyst.

[0036] Comparative Example 2:

[0037] 1wt% Pd / LaAlO x The catalyst preparation steps were repeated in Example 1, except that titanium isopropoxide was not added in the first step, while all other conditions remained the same, ultimately yielding 1 wt% Pd / LaAlO. x catalyst.

[0038] Example 2

[0039] Step 1: Dissolve 6.4984g La(NO3)3·6H2O and 54.4576g Al(NO3)3·9H2O in 200ml of deionized water, denoted as solution A. Dissolve 5.4458g titanium isopropoxide in 6.8072g of ethanol, denoted as solution B. While vigorously stirring, simultaneously add solution B and a 1mol / L ammonia solution to solution A to adjust the pH to 9.0. Stir the mixture for 3 hours, allow it to stand at room temperature for 12 hours to age, filter, wash repeatedly with deionized water until the filtrate is neutral, dry at 110℃ for 12 hours, and calcine at 400℃ in air for 4 hours to obtain Ti. 10 La 10 Al 80 O x A composite oxide support in which the molar ratio of Ti / La / Al is 10:10:80.

[0040] Step 2: Weigh 0.1189g Ni(NO3)2·6H2O and dissolve it in deionized water, then add 1.2g TiLaAlO x The powder was stirred in a 60°C water bath for 30 min, and the resulting mixture was subjected to vacuum rotary evaporation to remove excess moisture, obtaining a solid powder. The powder was dried overnight and calcined at 500°C for 4 h to obtain the modified support TiLaAlO. x -Ni, Ni loading 2wt%.

[0041] Step 3: Dissolve 4 mL of chloropalladium acid solution (Pd concentration in the solution is 2.5 g / L) in 20 mL of deionized water. Disperse 1.0 g of the modified carrier powder obtained in step 2 in the chloropalladium acid solution. Stir the resulting mixture in a 75°C water bath for 1 h, filter, dry at 110°C for 1 h, and calcine at 400°C for 4 h to obtain 1 wt% Pd / TiLaAlO x -Ni catalyst.

[0042] Example 3

[0043] The procedure was the same as in Example 2, except that in the second step, 0.1189 g Ni(NO3)2·6H2O was replaced with 0.1731 g Fe(NO3)3·9H2O, while all other conditions remained unchanged, to obtain 1 wt% Pd / TiLaAlO x -Fe catalyst, Fe loading 2wt%.

[0044] Example 4

[0045] The procedure was the same as in Example 2, except that in the second step, 0.1189 g Ni(NO3)2·6H2O was replaced with 0.1185 g Co(NO3)2·6H2O, while all other conditions remained unchanged, to obtain 1 wt% Pd / TiLaAlO x-Co catalyst.

[0046] Example 5

[0047] The procedure was the same as in Example 2, except that in the second step, 0.1189 g Ni(NO3)2·6H2O was replaced with 0.1033 g Y(NO3)3·6H2O, while all other conditions remained unchanged, to obtain 1 wt% Pd / TiLaAlO x -Y catalyst.

[0048] Example 6

[0049] The procedure is the same as in Example 2, except that in the second step, 0.1189g Ni(NO3)2·6H2O is replaced with 0.1388g C. 10 H5NbO 20 Under the same conditions, 1 wt% Pd / TiLaAlO was prepared. x -Nb catalyst.

[0050] Example 7

[0051] The procedure was the same as in Example 2, except that in the second step, 0.1189 g Ni(NO3)2·6H2O was replaced with 0.0906 g Cu(NO3)2·3H2O, while all other conditions remained unchanged, to obtain 1 wt% Pd / TiLaAlO x -Cu catalyst.

[0052] Application Example 1:

[0053] The catalysts prepared in Examples 1-7 were applied to the catalytic combustion of CO reaction. The reaction conditions were as follows: 0.1 g of catalyst was packed into a tubular reactor and heated to the catalytic combustion reaction temperature. The total flow rate of the gas feedstock was 100 ml / min, the reaction space velocity was 60000 ml / g·h, the volume fraction of CO in the gas feedstock was 1%, the SO2 concentration was 300 ppm, and the diluent gas for the gas feedstock was air.

[0054] Under the above test conditions, the comparison results of CO conversion rates when catalytic combustion reaches stability at different reaction temperatures are shown below. Figure 1 .from Figure 1 It can be seen that the catalysts in Examples 2, 3, and 5 have higher catalytic activity in the presence of SO2.

[0055] Under the test conditions described above, the 1wt% Pd / TiLaAlO3 sample from Example 1... x Catalyst, 1 wt% Pd / TiAlO2 of Comparative Example 1 x Catalyst and 1 wt% Pd / LaAlO in Comparative Example 2 xThe comparison results of CO conversion rates when catalytic combustion reaches a steady state are shown in the figure. Figure 2 .

[0056] Application Example 2:

[0057] The catalysts prepared in Examples 1, 2, and 5 were applied to the catalytic combustion of CO. The reaction conditions were as follows: 0.1 g of catalyst was packed into a tubular reactor, heated to the catalytic combustion reaction temperature of 220 °C, the total flow rate of the gaseous feedstock was 100 ml / min, the reaction space velocity was 60,000 ml / g·h, the volume fraction of CO in the gaseous feedstock was 1%, and the diluent gas for the gaseous feedstock was air. During the continuous catalytic combustion experiment, SO2 was introduced into the gaseous feedstock without introducing SO2 during the reaction time of 0-1 h, SO2 with a final concentration of 300 ppm was introduced into the gaseous feedstock during the reaction time of 1-4 h, and SO2 was again introduced into the gaseous feedstock without introducing SO2 during the reaction time of 4-7 h.

[0058] Under the above test conditions, the catalysts in Examples 1, 2, 5, 3, 4, 6, and 7 were applied to the continuous catalytic combustion of CO. The catalyst stability curves are shown below. Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 In other words, Figure 3-9 The 300ppm SO2 between the two dashed lines indicates that 300ppm SO2 gas was introduced during this time period, and the gas composition was CO + SO2 + air. During other time periods, it was CO + air.

[0059] Figure 2 The results of the performance test of the catalyst without additives show poor resistance to SO2. It begins to deactivate as soon as SO2 is introduced, and the conversion rate of CO drops sharply. Furthermore, the activity is difficult to recover after the introduction of SO2 is stopped, indicating that the catalyst is poisoned and causes irreversible deactivation. Figure 3 , 4 The addition of Ni and Y as modifiers improved the catalyst's sulfur resistance. The catalyst maintained a certain level of activity after SO2 was introduced, maintaining a CO conversion rate of over 75%, and the activity returned to 100% after the introduction of SO2 was stopped.

[0060] Figures 6-9 It can be seen that adding other modifying agents does not significantly improve the sulfur resistance of the catalyst.

[0061] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. The application of a low-temperature CO catalytic oxidation catalyst with high sulfur resistance in the catalytic combustion of CO, characterized in that... The catalyst is supported on TiLaAlO x A composite metal oxide, wherein an active ingredient and an auxiliary metal M are loaded onto a support, the active ingredient being the noble metal Pd, with a Pd loading of 0.5-2%, and the auxiliary metal M loading of 1-2%, wherein TiLaAlO x The molar ratio of Ti, La, and Al in the composite metal oxide is 8-12:8-12:80; the auxiliary metal M is one or both of Ni and Y.

2. The application as described in claim 1, characterized in that... The catalyst preparation method includes the following steps: S1: According to TiLaAlO x A composite metal oxide containing Ti, La, and Al in a specific molar ratio was prepared by dissolving La(NO3)3·6H2O and Al(NO3)3·9H2O together in water. A titanium isopropoxide solution diluted with ethanol was added dropwise, and the pH was adjusted to 8.0–10.0 with alkali. The mixture was stirred for 0.5–4 h, then allowed to stand at room temperature for 10–15 h to age. After filtration, the mixture was washed several times with deionized water and anhydrous ethanol until the filtrate was neutral. It was then dried and calcined at 300–600 °C for 2–5 h in air to obtain TiLaAlO. x Composite oxide powder; S2: Dissolve the nitrate of metal M in deionized water, and add TiLaAlO. x The composite oxide powder was stirred in a water bath at 50-70℃ for 20-60 min, and the resulting mixture was subjected to vacuum rotary evaporation to remove excess water to obtain a solid powder. After drying overnight, it was calcined at 300-600℃ for 2-5 h to obtain the modified support TiLaAlOx-M. S3: The noble metal is loaded using the equal volume impregnation method. The carrier powder obtained in step S2 is impregnated in an aqueous solution of Pd precursor. The resulting mixture is stirred in a water bath at 65-85°C for 1-3 h to allow the noble metal Pd to be fully adsorbed on the carrier surface. Then, it is filtered, dried, and calcined in air at 300-600°C for 2-5 h to complete the preparation.

3. The application as described in claim 2, characterized in that... In steps S1, S2, or S3, the calcination temperature is 380-420℃.

4. The application as described in claim 2, characterized in that... In step S3, the temperature of the stirring reduction reaction is 65-85℃, and the reaction time is 0.5-2h.

5. The application as described in claim 1, characterized in that... The catalyst is packed into a tubular reactor and heated to the reaction temperature for catalytic combustion. Air is used as a dilution gas to dilute the CO gas to form a gaseous feedstock, which is then introduced into the tubular reactor for catalytic combustion.

6. The application as described in claim 5, characterized in that... The CO gas concentration in the gaseous feedstock is 1000ppm–20000ppm, the SO2 gas concentration is 0–600ppm, and the reaction space velocity is 20000–80000 mL·g. -1 ·h -1 .

7. The application as described in claim 6, characterized in that... The CO gas concentration in the gaseous feedstock is 5000-10000 ppm.

8. The application as described in claim 6, characterized in that... The reaction temperature for catalytic combustion is 160-250℃.

9. The application as described in claim 8, characterized in that... The reaction temperature for catalytic combustion is 200-220℃.

10. The application as described in claim 6, characterized in that... The SO2 gas concentration in the gaseous feedstock is below 300 ppm.

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