Surface-modified perovskite oxides and methods of modifying and using the same
By modifying the surface of perovskite oxides with Ti element, the problems of poor catalytic activity and sulfur resistance were solved, resulting in a highly efficient and stable CO oxidation catalyst suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUATIAN ENG & TECH CORP MCC
- Filing Date
- 2024-06-27
- Publication Date
- 2026-07-31
AI Technical Summary
Existing perovskite oxide catalysts suffer from insufficient catalytic activity and poor sulfur resistance in the catalytic oxidation of CO, which restricts their widespread application.
By impregnating perovskite oxide powder in TiCl4 solution and then calcining it at a specific temperature and atmosphere, Ti elements are loaded onto the surface of the perovskite oxide to form a surface-modified perovskite oxide catalyst.
It improves catalytic activity and sulfur resistance, becoming a highly efficient and stable CO oxidation catalyst suitable for industrial production.
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Figure CN118831600B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalytic removal technology of gaseous pollutants, specifically relating to a surface-modified perovskite oxide, its modification method, and its uses. Background Technology
[0002] Carbon monoxide (CO) is a low-quality combustible gas produced by the incomplete combustion of carbon-containing fuels such as coal and petroleum. Improper use can lead to its harmful effects, causing serious environmental and atmospheric pollution due to its emission alongside industrial flue gas. Catalytic oxidation is the most widely used low-concentration CO removal technology in industrial production and daily life. This technology converts CO into CO2 gas at a certain temperature in an oxygen-containing atmosphere through the action of a catalyst, before it is emitted. The catalyst is the core of catalytic oxidation technology; a stable, durable, and inexpensive catalyst is crucial for the efficient catalytic elimination of gaseous pollutants.
[0003] Currently, catalysts used in the catalytic oxidation of CO are mainly divided into noble metal catalysts and non-noble metal catalysts. Among non-noble metal catalysts, perovskite oxides are considered a very promising class of catalysts. Perovskite is a type of metal oxide with the structure ABO3, where the A-site is usually a rare earth or alkaline earth metal element, such as La, Sr, and Ba, the B-site is a transition metal element, such as Co, Mn, Fe, and Ni, and O is oxygen. Perovskite oxides have good thermal stability and excellent redox properties. In addition, compared with common noble metal catalysts, perovskite catalysts are relatively inexpensive, thus attracting more and more research teams to dedicate themselves to developing perovskite catalysts with superior performance.
[0004] Although perovskite oxides possess unique advantages in terms of thermal stability and cost, they still lag significantly behind precious metal catalysts in catalytic activity. Furthermore, perovskite oxides exhibit relatively poor stability and impurity tolerance in practical applications. Specifically, in actual CO gas pollution treatment, the gas to be treated often contains multiple impurities, such as H₂O and NO₂. x Sulfur-containing components, such as SO2, significantly reduce the catalytic activity of perovskite oxides. These two points are the main obstacles restricting their further development and widespread application.
[0005] It is well known that the catalytic activity of perovskite oxides is closely related to their physicochemical properties, especially the surface physicochemical properties. To address these two types of issues, researchers have attempted to improve the catalytic activity and sulfur resistance of perovskite catalysts by optimizing the catalyst composition (e.g., doping other elements at the A and B sites of the perovskite, or using non-chemical dosages at the A and B sites), improving preparation methods (ceramic method, sol-gel method, co-precipitation method, flame spray method), modifying the surface of the perovskite catalyst, and constructing special porous structures. However, the mainstream technologies reported so far have limited effectiveness in improving catalyst performance, especially in resisting sulfur deactivation. Furthermore, the processes for preparing or improving these catalysts are generally cumbersome and involve numerous steps, further limiting the potential for commercial-scale application.
[0006] Therefore, based on existing perovskite oxides, it is particularly important to develop a low-cost perovskite oxide with a simple preparation process, high catalytic activity, high impurity tolerance, and suitable for surface modification of CO catalytic oxidation technology, as well as its modification method. Summary of the Invention
[0007] To overcome the above problems, the present invention aims to provide a surface-modified perovskite oxide catalyst.
[0008] To achieve the above objectives, the surface modification method for perovskite oxides of the present invention includes the following steps:
[0009] Step 1: Impregnate the perovskite oxide powder in the modified solution, then filter and dry the resulting solid;
[0010] Step 2: Calcine the dried solid to obtain the modified perovskite oxide;
[0011] Furthermore, the perovskite oxide in step 1 has the composition form of ABO3, where A represents one or more rare earth and alkaline earth metal elements; B represents one or more transition metal elements; and the particle size of the perovskite oxide powder is less than 0.1 mm.
[0012] Furthermore, the modified solution in step 1 is an aqueous solution of TiCl4 or an ethanol solution with a concentration of 2 mmol / L to 100 mmol / L.
[0013] Furthermore, in the impregnation process described in step 1, the ratio of perovskite oxide mass to modified solution volume is between 8 g (perovskite) / L (modified solution) and 40 g (perovskite) / L (modified solution), the impregnation temperature is between 5 and 40°C, and the impregnation time is between 20 and 600 s.
[0014] Furthermore, the drying process described in step 1 refers to drying at 50–100°C for 5–20 hours.
[0015] Furthermore, the calcination treatment mentioned in step 2 refers to calcination at 250–600°C for 1–10 hours.
[0016] Furthermore, the calcination process described in step 2 is carried out in an air atmosphere, an inert gas atmosphere, or a mixture of air and inert gas atmosphere; wherein the inert gas is one or more of nitrogen, argon, and helium.
[0017] To achieve the above objectives, the present invention provides a surface-modified perovskite oxide prepared by the above-described modification method.
[0018] Furthermore, the molar percentage of Ti on the surface of the surface-modified perovskite oxide, as detected by XPS, is 2-20%.
[0019] To achieve the above objectives, the present invention relates to the use of the surface-modified perovskite oxide according to the above description as a catalyst in the catalytic oxidation of CO.
[0020] Compared with the prior art, the present invention has the following advantages:
[0021] This invention effectively loads more stable titanium elements onto the surface of perovskite oxides through surface modification. Compared with ordinary perovskite oxides, the surface-modified perovskite of this invention not only has higher catalytic activity, but also high stability and high sulfur resistance, making it a stable and efficient CO oxidation catalyst.
[0022] Furthermore, the perovskite oxide surface modification method of the present invention is simple in steps, easy to operate, and easy to scale up for production, which can save a lot of costs for industrial production.
[0023] Furthermore, the surface-modified perovskite catalyst of the present invention can be applied to the catalytic oxidation of CO. Attached Figure Description
[0024] Figure 1 The graphs show the performance of CO oxidation catalytic oxidation of the samples obtained in Examples 1-3 of this invention and the sample in Comparative Example 1.
[0025] Figure 2 The graphs show the CO catalytic stability test curves of the samples in Example 1 and Comparative Example 1 of this invention under a sulfur-containing atmosphere. Detailed Implementation
[0026] The present invention will be further described in detail below with reference to specific embodiments.
[0027] Example 1:
[0028] Step 1: [The following appears to be a separate, unrelated section:] ...the chemical formula La 0.6 Sr 0.4CoO3 perovskite oxide powder was impregnated in a modified solution, filtered, and then the resulting solid was dried at 60°C for 5 h. The modified solution was a 36 mmol / L TiCl4 aqueous solution, the ratio of perovskite oxide powder to modified solution was 20 g (perovskite) / L, the impregnation time was 120 s, and the impregnation temperature was 25°C.
[0029] Step 2: The dried solid was calcined at 260°C for 3 hours in air to obtain the surface-modified perovskite oxide, denoted as La. 0.6 Sr 0.4 CoO3-Ti - Example 1. XPS characterization results showed that the molar percentage of La on the perovskite oxide surface was 10.3%, Sr was 3.8%, Co was 9.2%, Ti was 10.0%, and O was 66.9%, indicating that titanium had been successfully loaded onto the perovskite surface.
[0030] Example 2:
[0031] Step 1: [The following appears to be a separate, unrelated section:] ...the chemical formula La 0.6 Sr 0.4 CoO3 perovskite oxide powder was impregnated in a modified solution, filtered, and then the resulting solid was dried at 60°C for 5 h. The modified solution was a 36 mmol / L TiCl4 ethanol solution, the ratio of perovskite oxide powder to modified solution was 20 g (perovskite) / L, the impregnation time was 120 s, and the impregnation temperature was 25°C.
[0032] Step 2: The dried solid was calcined at 260°C for 3 hours in air to obtain the surface-modified perovskite oxide, denoted as La. 0.6 Sr 0.4 CoO3-Ti - Example 2.
[0033] Example 3:
[0034] Step 1: [The following appears to be a separate, unrelated section:] ...the chemical formula La 0.6 Sr 0.4 CoO3 perovskite oxide powder was impregnated in a modified solution, filtered, and then the resulting solid was dried at 60°C for 5 h. The modified solution was a 36 mmol / L TiCl4 aqueous solution, the ratio of perovskite oxide powder to modified solution was 20 g (perovskite) / L, the impregnation time was 120 s, and the impregnation temperature was 25°C.
[0035] Step 2: The dried solid was calcined at 500℃ for 3 hours in air to obtain the surface-modified perovskite oxide, denoted as La. 0.6 Sr 0.4 CoO3-Ti - Example 3
[0036] Comparative Example 1:
[0037] The chemical formula is La 0.6 Sr 0.4 CoO3 perovskite oxides were not subjected to any additional treatment, and the resulting sample was La. 0.6 Sr 0.4 CoO3- Comparative Example 1.
[0038] Figure 1 The samples obtained in Examples 1-3 of this invention and La in Comparative Example 1 0.6 Sr 0.4 Performance test chart of CoO3 sample for catalytic oxidation of CO. Test conditions: Catalyst particles with a diameter of 0.075-0.1 mm were selected by sieving for CO catalytic oxidation activity evaluation; 0.2 g catalyst, CO 6000 ppm, O2 15%, gas hourly space velocity (GHSV) 90,000 mL / h. -1 g -1 .
[0039] from Figure 1 It can be seen that the CO conversion rate of the surface-modified samples of Examples 1-3 is higher than that of the unmodified Comparative Example 1 sample at the same temperature, indicating that the catalytic activity of the modified catalyst samples of Examples 1-3 in the CO catalytic oxidation reaction has been significantly improved, proving that the surface modification method can effectively improve the activity of perovskite oxide catalytic CO oxidation.
[0040] Figure 2 The sample obtained in Example 1 of this invention and the La in Comparative Example 1 are examples of samples from this invention. 0.6 Sr 0.4 Stability curves of CoO3 samples under sulfur-containing atmosphere. Test conditions: Catalyst particles with a diameter of 0.075-0.11 mm were selected by sieving for evaluation of CO catalytic oxidation activity under sulfur-containing atmosphere. 0.2 g catalyst, CO 6000 ppm, SO2 20 ppm, O2 15%, gas hourly space velocity (GHSV) 90,000 mL h⁻¹ -1 g -1 The reaction temperature is 250℃.
[0041] from Figure 2 It can be seen that the CO conversion rate of the Comparative Example 1 sample decreased rapidly after SO2 atmosphere was introduced, while the catalytic activity of the Example 1 sample did not decrease after SO2 atmosphere was introduced, and the CO conversion rate only began to decrease slowly after the high conversion rate was maintained for a long time. This result shows that the surface-modified perovskite catalyst has a significant improvement in sulfur resistance.
[0042] The present invention has been described in detail above, but it is not limited to the embodiments described above. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the invention. Many other changes and modifications made without departing from the concept and scope of the invention should be considered within the scope of protection of the present invention.
[0043] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.
[0044] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. The use of a surface-modified perovskite oxide in the catalytic oxidation of carbon monoxide, characterized in that, The surface modification method for this perovskite oxide includes the following steps: Step 1: Impregnate the perovskite oxide powder in a modification solution, then filter and dry the resulting solid; the perovskite oxide has the composition ABO3, where A represents one or more rare earth and alkaline earth metal elements; B represents one or more transition metal elements; and O represents oxygen; the particle size of the perovskite oxide powder is less than 0.1 mm; the modification solution is a TiCl4 aqueous solution or ethanol solution with a concentration of 2 mmol / L to 100 mmol / L; during the impregnation process, the mass ratio of perovskite oxide to modification solution volume is 8 g / L to 40 g / L, the impregnation temperature is 5 to 40 ℃, and the impregnation time is 20 to 600 s; Step 2: Calcine the dried solid to obtain the modified perovskite oxide; Surface-modified perovskite oxides exhibit high sulfur resistance.
2. The use of the surface-modified perovskite oxide according to claim 1 in the catalytic oxidation of carbon monoxide, characterized in that, The drying process described in step 1 refers to drying at 50~100 ℃ for 5~20 h.
3. The use of the surface-modified perovskite oxide according to claim 1 in the catalytic oxidation of carbon monoxide, characterized in that, The calcination treatment mentioned in step 2 refers to calcination at 250~600℃ for 1~10 h.
4. The use of the surface-modified perovskite oxide according to claim 1 in the catalytic oxidation of carbon monoxide, characterized in that, The calcination described in step 2 is carried out in an air atmosphere, an inert gas atmosphere, or a mixture of air and inert gas atmosphere; wherein the inert gas is one or more of nitrogen, argon, and helium.