Non-noble metal doped perovskite catalyst suitable for multi-element fuel engine and preparation method of non-noble metal doped perovskite catalyst

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a non-noble metal doped perovskite catalyst suitable for a multi-element fuel engine and a preparation method of the non-noble metal doped perovskite catalyst. According to the non-noble metal doped perovskite catalyst, La is used as A-site metal, Mn is used as B-site metal, and Sr and K elements are doped and introduced into the A site; fe element is doped and introduced into the B site; the expression of the perovskite type catalyst is La1-x-ySrxKyMn1-zFezO3, x is more than or equal to 0.05 and less than or equal to 0.2, y is more than or equal to 0.05 and less than or equal to 0.2, z is more than or equal to 0 and less than or equal to 0.2, and x + y is more than or equal to 0.1 and less than or equal to 0.4. The three-dimensional macroporous structure of the catalyst increases the specific surface area and active sites, and promotes reactant transmission and catalytic efficiency; sr, K and Fe are co-doped, so that the oxygen storage capacity and the oxidation-reduction performance are improved, and the activation energy is reduced; and under the condition of extremely low dosage, the ignition temperature of smoke dust is obviously reduced, and the CO conversion rate of 90% or above is realized at about 230 DEG C.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a doped non-precious metal perovskite catalyst suitable for multi-fuel engines and its preparation method. Background Technology

[0002] With the continuous development of the automotive industry and the increasing environmental awareness of the public, engines powered by natural gas and methanol are gaining popularity due to their environmental friendliness and economy. However, these clean fuel engines still inevitably emit some CO and particulate matter (PM) in their exhaust. Internal combustion engines, due to their strong adaptability and high fuel energy density, are widely used in vehicles, ships, and aircraft, but they emit large amounts of CO, hydrocarbons (HC), and particulate matter (PM) during operation, causing serious harm to the environment and human health. Currently, efficient exhaust aftertreatment technology is key to controlling these emissions. Traditional precious metal catalysts, while possessing high activity, are expensive and prone to poisoning, limiting their widespread application. Perovskite oxides (ABO3), with their tunable structure, low cost, and good stability, have become an ideal alternative to precious metal catalysts. However, traditional perovskite catalysts suffer from problems such as small specific surface area, few active sites, and poor oxygen migration ability, resulting in poor low-temperature catalytic performance.

[0003] While existing technologies have explored ways to improve perovskite performance through single or bimetallic doping, significant breakthroughs have often been limited in optimizing surface oxygen species activity and achieving multi-mechanism synergistic catalysis. Therefore, developing a non-noble metal perovskite catalyst that combines abundant oxygen vacancies, excellent low-temperature activity, and good stability is of great importance. Summary of the Invention

[0004] The purpose of this invention is to address the problems of existing perovskite catalysts, such as small specific surface area, few active sites, and poor oxygen migration ability, which lead to poor catalytic performance at low temperatures. The invention provides a doped non-precious metal perovskite catalyst that is easy to prepare, has high catalytic activity, and is low in cost.

[0005] Specifically, this invention provides a doped non-noble metal perovskite catalyst suitable for multi-fuel engines. The doped non-noble metal perovskite catalyst uses La as the A-site metal and Mn as the B-site metal. Sr and K elements are introduced at the A-site, with a molar ratio of Sr to K of 1:1; Fe element is introduced at the B-site. The perovskite catalyst formula is La... 1-x- y Sr x K y Mn 1-z Fe z O3, where 0.05≤x≤0.2, 0.05≤y≤0.2, 0≤z≤0.2, and 0.1≤x+y≤0.4.

[0006] Furthermore, when z=0, the doped non-noble metal perovskite catalyst has a three-dimensional porous structure with an average pore size of 0.3-0.8 μm, and Sr and K elements are uniformly distributed in the perovskite lattice.

[0007] Furthermore, when 0 < z ≤ 0.2, the doped non-noble metal perovskite catalyst has a honeycomb macroporous structure with an average pore size of 2-5 μm, and Sr, K, and Fe elements are uniformly distributed in the perovskite lattice; the surface of the macroporous structure is coated with nanocrystals with an average grain size of 10-25 nm.

[0008] This invention also provides a method for preparing a doped non-noble metal perovskite catalyst, characterized in that the method includes the following steps: S1: Weigh the carbonates of La, Mn, Sr, K, and Fe according to the stoichiometric ratio shown in the expression, dissolve them in deionized water, and stir until they are evenly dispersed; add citric acid equal to the total number of moles of metal ions, and sonicate until the citric acid is completely dissolved to obtain a clear mixed solution; S2: Add an alkaline solution dropwise to the clarified mixed solution to adjust the pH of the system to a stable value of 7-8, and continue stirring until a viscous gel-like precursor is formed; S3: Dry the viscous gel-like precursor to obtain a solid precursor; S4: The solid precursor is calcined in air in two steps; in the first step, the temperature is increased to 350-450℃ at 2-5℃ / min and held for 1-3 hours; in the second step, the temperature is increased to 650-750℃ at 3-7℃ / min and held for 2-4 hours, followed by natural cooling to obtain a doped non-precious metal perovskite catalyst.

[0009] Furthermore, the ultrasonic treatment described in S1 specifically refers to ultrasonic treatment at 300-500W for 15-30 minutes.

[0010] Furthermore, the alkaline solution mentioned in S2 is an ammonia solution with a mass fraction of 20%-30%.

[0011] Furthermore, the drying temperature described in S3 is 65-75°C.

[0012] Furthermore, the air atmosphere described in S4 is introduced at a flow rate of 40-60 mL / min.

[0013] The present invention also provides an application of a non-precious metal doped perovskite catalyst, wherein the catalyst is used for exhaust gas purification.

[0014] Furthermore, the exhaust gas purification refers to the purification of soot and carbon monoxide in the exhaust gas of a fuel engine or internal combustion engine.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The catalyst of this invention, even at extremely low dosages, can reduce the ignition temperature (T) of flue gas. 10 The temperature drops by more than 100°C, reducing the complete combustion temperature (T). 90 The conversion rate of CO was significantly advanced; the CO conversion rate reached 90% at 237℃ and 221℃, respectively, and the conversion rate exceeded 94% and 96% at 250℃, respectively; the CO2 selectivity continued to improve, exceeding 96% at 328℃ and 337℃, respectively.

[0016] 2. The three-dimensional macroporous structure of this invention significantly increases the specific surface area of ​​the catalyst, providing more active and adsorption sites for capturing CO and PM in the exhaust gas and catalyzing their reaction. This promotes the contact between carbon black and the active sites, significantly improving the efficiency of solid-phase catalytic reactions. This macroporous structure also accelerates the rapid transport of reactants and products, reducing diffusion limitations and thus promoting catalytic oxidation reactions.

[0017] 3. The co-doping of Sr, K, and Fe elements in this invention not only stabilizes the crystal structure but also significantly enhances the oxygen storage capacity and redox capability of the catalyst. The multi-component metals alter electron transfer between ions, weakening the binding of oxygen to organic matter. Iron further enhances the catalyst's oxygen storage capacity, promoting the exchange of oxygen atoms in the surface carbonate with organic matter in the peroxide, thus reducing the activation energy required for catalysis.

[0018] 4. This invention uses only non-precious metal elements, resulting in low raw material costs. It does not require loading precious metals such as Pt and Ag, and the raw material cost is only 1 / 5 to 1 / 10 of that of precious metal catalysts. The preparation process is green and suitable for industrial production and widespread application. Attached Figure Description

[0019] Figure 1 Scanning electron microscope (SEM) images of Experimental Example 1: a) Catalyst LM prepared in Comparative Example 1, b) Catalyst LM prepared in Comparative Example 2. + c represents the LSM catalyst prepared in Comparative Example 3. + d represents the LSM catalyst prepared in Comparative Example 6. + / Ag, e represents the catalyst LSKM prepared in Comparative Example 4, and f represents the catalyst LSKM prepared in Example 1. + g represents the LSKMFe catalyst prepared in Comparative Example 5, and h represents the LSKMFe catalyst prepared in Example 2. + il is LSKM, LSKM + LSKMFe, LSKMFe + Enlarged electron microscope (SEM) image of the catalyst.

[0020] Figure 2The catalyst LSKMFe prepared in Example 2 + Energy dispersive spectroscopy (EDS) test image.

[0021] Figure 3 Catalyst LSKM prepared in Examples 1-2, Comparative Examples 2-3, and Comparative Examples 6-7 + 、LSKMFe + LM + LSM + LSM + / Ag、LSM + X-ray photoelectron spectroscopy (XPS) of / Pt.

[0022] Figure 4 Graph showing the CO conversion rate and CO2 selectivity of the catalyst in Experiment Example 3, where a is the LSKM. + CO conversion performance curve, b is LSKMFe + CO conversion performance curve, c is LSKM + The selectivity performance curve of flue gas conversion, d is LSKMFe + The selectivity performance curve of flue gas conversion.

[0023] Figure 5 : TG / DTG curves of Experimental Example 3, a is the TG / DTG curve of flue gas, b is the TG / DTG curve of catalysts LM and LM prepared in Comparative Examples 1 and 2. + The TG / DTG curves are shown, with c representing the LSM catalyst prepared in Comparative Example 3. + The TG / DTG curves are shown, where d represents the LSM catalyst prepared in comparative examples 6 and 7. + / Ag、LSM + The TG / DTG curves of / Pt, where e represents the LSKM catalyst prepared in Example 1 and Comparative Example 4. + The TG / DTG curves of LSKM, f represents the catalysts LSKMFe prepared in Example 2 and Comparative Example 5. + TG / DTG curves of LSKMFe. Detailed Implementation

[0024] The following examples further illustrate specific implementations of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.

[0025] Example 1 La doped non-noble metal perovskite catalyst 0.8 Sr0.1 K 0.1 MnO3 (i.e. LSKM) + Preparation of ) S1: Precursor mixing: 0.02 mmol La2(CO3)3·xH2O, 0.04 mmol MnCO3, 0.004 mmol SrCO3, and 0.002 mmol K2CO3 were added to 100 mL of deionized water and stirred at 500 r / min until evenly dispersed; 0.088 mmol citric acid was added and the mixture was sonicated at 400 W for 20 min to ensure complete dissolution of the citric acid, resulting in a clear mixed solution; S2: Doping: Slowly add 25% ammonia solution, monitor the pH value in real time until the pH of the system stabilizes at 7.5, continue stirring until the solution forms a viscous gel-like precursor (without obvious stratification). S3: Drying pretreatment: Transfer the gel-like precursor to a ceramic boat, place it in a muffle furnace, set the temperature to 70℃, and keep it at that temperature for 12 hours. During this period, observe it regularly to prevent the precursor from overflowing. After drying, the precursor is a light yellow solid with a loose texture. S4: Two-step calcination: The dried precursor was transferred to a quartz boat in a tubular furnace, and air was introduced (flow rate 50 mL / min); First calcination: The temperature was increased to 400℃ at 3℃ / min and held for 2 hours to remove acidic groups such as CO2 and H2O produced by the decomposition of citric acid; Second calcination: The temperature was increased to 700℃ at 5℃ / min and held for 3 hours to promote the formation of the perovskite crystal phase; After calcination, the tubular furnace was closed and allowed to cool naturally to room temperature to obtain the black powdered target catalyst, namely the non-precious metal doped perovskite catalyst LSKM. + .

[0026] Performance testing: Resulting LSKM + The catalyst has a specific surface area of ​​68.5 m². 2 / g, CO conversion rate at 250℃ is 94.2%, and flue gas T 50 =445.2℃, CO2 selectivity 96.1%.

[0027] Example 2 La doped non-noble metal perovskite catalyst 0.8 Sr 0.1 K 0.1 Mn 0.8 Fe 0.2 O3 (i.e., LSKMFe) + Preparation of ) S1: Precursor Mixture: 0.02 mmol La2(CO3)3·xH2O, 0.04 mmol MnCO3, 0.004 mmol SrCO3, 0.002 mmol K2CO3, and 0.008 mol FeCO3 were added to 100 mL of deionized water and stirred at 500 r / min until evenly dispersed; 0.096 mol citric acid was added, and the mixture was sonicated at 500 W for 25 min to ensure complete dissolution of the citric acid, resulting in a clear mixed solution; S2: Doping: Slowly add 25% ammonia solution, monitor the pH value in real time until the pH of the system stabilizes at 7.2, continue stirring until the solution forms a viscous gel-like precursor (without obvious stratification). S3: Drying pretreatment: Transfer the gel-like precursor to a ceramic boat, place it in a muffle furnace, set the temperature to 70℃, and keep it at that temperature for 12 hours. During this period, observe it regularly to prevent the precursor from overflowing. After drying, the precursor is a light yellow solid with a loose texture. S4: Two-step calcination: The dried precursor was transferred to a quartz boat in a tubular furnace, and air was introduced (flow rate 50 mL / min); First calcination: The temperature was increased to 400℃ at 3℃ / min and held for 2 hours to remove acidic groups such as CO2 and H2O produced by the decomposition of citric acid; Second calcination: The temperature was increased to 700℃ at 5℃ / min and held for 3 hours to promote the formation of the perovskite crystal phase; After calcination, the tubular furnace was closed and allowed to cool naturally to room temperature to obtain the black powdered target catalyst, namely the non-precious metal doped perovskite catalyst LSKM. + .

[0028] Performance testing: Resulting LSKMFe + The catalyst has a specific surface area of ​​75.3 m². 2 / g, CO conversion rate of 96.5% at 250℃, dust T 50 =518.1℃, CO2 selectivity 96.5%.

[0029] Example 3 La doped non-noble metal perovskite catalyst 0.9 Sr 0.05 K 0.05 Mn 0.9 Fe 0.1 O3 (i.e., LSKMFe) + Preparation of ) S1: Precursor Mixture: 0.02 mmol La2(CO3)3·xH2O, 0.04 mmol MnCO3, 0.002 mmol SrCO3, 0.001 mmol K2CO3, and 0.004 mol FeCO3 were added to 50 mL of deionized water and stirred at 500 r / min until evenly dispersed; 0.088 mol citric acid was added, and the mixture was sonicated at 300 W for 30 min to ensure complete dissolution of the citric acid, resulting in a clear mixed solution; S2: Doping: Slowly add 20% ammonia solution, monitor the pH value in real time, until the pH of the system stabilizes at 7.2, continue stirring until the solution forms a viscous gel-like precursor (without obvious stratification). S3: Drying pretreatment: Transfer the gel-like precursor to a ceramic boat, place it in a muffle furnace, set the temperature to 70℃, and keep it at that temperature for 12 hours. During this period, observe it regularly to prevent the precursor from overflowing. After drying, the precursor is a light yellow solid with a loose texture. S4: Two-step calcination: The dried precursor was transferred to a quartz boat in a tubular furnace, and air was introduced (flow rate 50 mL / min); First calcination: The temperature was increased to 350℃ at 5℃ / min and held for 3 hours to remove acidic groups such as CO2 and H2O produced by the decomposition of citric acid; Second calcination: The temperature was increased to 650℃ at 3℃ / min and held for 2 hours to promote the formation of the perovskite crystal phase; After calcination, the tubular furnace was closed and allowed to cool naturally to room temperature to obtain the black powdered target catalyst, namely the non-precious metal doped perovskite catalyst LSKM. + .

[0030] Example 4 La doped non-noble metal perovskite catalyst 0.6 Sr 0.2 K 0.2 MnO3 (i.e. LSKM) + Preparation of ) S1: Precursor mixing: 0.02 mmol La2(CO3)3·xH2O, 0.04 mmol MnCO3, 0.008 mmol SrCO3, and 0.004 mmol K2CO3 were added to 100 mL of deionized water and stirred at 500 r / min until evenly dispersed; 0.092 mol citric acid was added and the mixture was sonicated at 450 W for 25 min to ensure complete dissolution of the citric acid, resulting in a clear mixed solution; S2: Doping: Slowly add 30% ammonia solution, monitor the pH value in real time until the pH of the system stabilizes at 7.5, continue stirring until the solution forms a viscous gel-like precursor (without obvious stratification). S3: Drying pretreatment: Transfer the gel-like precursor to a ceramic boat, place it in a muffle furnace, set the temperature to 70℃, and keep it at that temperature for 12 hours. During this period, observe it regularly to prevent the precursor from overflowing. After drying, the precursor is a light yellow solid with a loose texture. S4: Two-step calcination: The dried precursor was transferred to a quartz boat in a tubular furnace, and air was introduced (flow rate 50 mL / min); First calcination: The temperature was increased to 450℃ at 3℃ / min and held for 1 h to remove acidic groups such as CO2 and H2O produced by the decomposition of citric acid; Second calcination: The temperature was increased to 750℃ at 7℃ / min and held for 4 h to promote the formation of the perovskite crystal phase; After calcination, the tubular furnace was closed and allowed to cool naturally to room temperature to obtain the black powdered target catalyst, namely the non-precious metal doped perovskite catalyst LSKM. + .

[0031] Comparative Example 1 Preparation of unmodified LaMnO3 (i.e., LM) catalyst: Using only La2(CO3)3·xH2O and MnCO3, without doping with Sr, K, or Fe, and without adding 25% ammonia solution, the remaining steps are the same as in Example 1.

[0032] Performance: Specific surface area 28.3 m² 2 / g, CO conversion rate at 250℃ is 35.7%, dust T 50 =601.8℃, which is significantly lower than the catalyst of this invention.

[0033] Comparative Example 2 Modified LaMnO3 (i.e., LM) + Catalyst preparation: Only La2(CO3)3·xH2O and MnCO3 were used, without doping with Sr, K, or Fe, and the remaining steps were the same as in Example 1.

[0034] Performance: Smoke and Dust T 50 =576.2℃, the performance is significantly lower than that of the catalyst of this invention.

[0035] Comparative Example 3 LSM + Catalyst preparation: Using La2(CO3)3·xH2O with MnCO3 and SrCO3, without doping with K and Fe, the remaining steps are the same as in Example 1.

[0036] Comparative Example 4 LSKM catalyst preparation: The difference from Example 1 is that no 25% ammonia solution is added; the rest of the steps are the same as in Example 1.

[0037] Comparative Example 5 LSKMFe catalyst preparation: The difference from Example 2 is that no 25% ammonia solution is added; the rest of the steps are the same as in Example 2.

[0038] Comparative Example 6 Ag load type LSM + Catalyst (i.e., LSM) + Preparation of / Ag): (1) LSM was prepared according to the method in Example 1. + The difference is that K2CO3 is not added.

[0039] (2) Add a 2% solution of ethylene glycol and Ag(NO3)2 to LSM + The mixture was then sonicated, allowed to stand for 12 hours, and then calcined to obtain LSM. + / Ag.

[0040] Performance: CO conversion rate of 95.8% at 250℃, dust concentration (T) 50 =518.1℃, compared with the LSKMFe of the present invention + Comparable performance, but at a cost of LSKMFe + 5-10 times.

[0041] Comparative Example 7 Pt-loaded LSM + Catalyst (i.e., LSM) + / Pt) preparation: (1) LSM was prepared according to the method in Example 1. + The difference is that K2CO3 is not added.

[0042] (2) Add a 2% solution of ethylene glycol and Pt(NO3)2 to LSM + The mixture was then sonicated, allowed to stand for 12 hours, and then calcined to obtain LSM. + / Pt.

[0043] Performance: CO conversion rate of 95.8% at 250℃, dust concentration (T) 50 =570.7℃, compared to the LSKMFe of this invention + High, and the cost is LSKMFe + 5-10 times.

[0044] Experimental Example 1: Physicochemical Properties of Catalysts 1. The catalysts prepared in Examples 1-2 and Comparative Examples 1-6 were observed using a scanning electron microscope (SEM). Figure 1 a- Figure 1As shown in h, LM has a smaller specific surface area, while the modified LM + It exhibits a distinct plate-like and layered structure with a significantly increased specific surface area; LSKM + It exhibits a typical three-dimensional porous structure with pore sizes of 0.3-0.8 μm; LSKMFe + Under an electron microscope, the catalyst exhibits a three-dimensional porous honeycomb structure with pore sizes of 2-5 μm and aggregated nanocrystals (active sites) with a grain size of 10-25 nm. This micron-sized pore structure significantly increases the catalyst's specific surface area, providing more active and adsorption sites for capturing CO and PM in the exhaust gas and catalyzing their reaction. This promotes contact between the carbon black and the active sites, significantly improving the efficiency of the solid-phase catalytic reaction. The porous structure also accelerates the rapid transport of reactants and products, reducing diffusion limitations and thus promoting the catalytic oxidation reaction.

[0045] like Figure 1 The scanning electron microscope magnification image of i-l shows LSKM and LSKM. + Having similar structures, alkaline solutions, while not significantly altering their characteristic structures, do loosen the stacking between crystals. Fe B-site doping changes the grain size; larger cubic grains appear on the LSKMFe surface, while LSKMFe... + The grain size is reduced. The addition of alkaline solution alters the precursor formation environment, weakens the bonding strength between the metal and oxygen atoms, and inhibits excessive crystal growth.

[0046] 2. The LSKMFe prepared in Example 2 + Perform energy-dispersive spectroscopy (EDS) tests, such as Figure 2 As shown in the elemental distribution diagram, LSKMFe + The uniform elemental distribution further confirms that the La / Mn ions at the A / B sites have been successfully replaced, demonstrating that non-noble metal elements (K, Sr, and Fe) have been successfully incorporated into the LaMnO3 eutectic structure.

[0047] 3. Surface chemical state of the example: At high temperatures, carbonates and hydroxides can decompose to form metal oxides with multiple active sites on the surface. This process supplements O. L And form O V To adsorb CO molecules and activate their activity. On the surface of the oxygen-containing catalyst, O... V With O C It is considered as ROS. The higher the ROS ratio, the better the catalytic performance. The three oxygen species can be converted into O2 during the catalytic process. V O L O C Forms can transform into each other. The weakly alkaline preparation environment causes the precursor to generate more ROS during stirring and drying. These ROS, after adsorbing onto the catalyst surface, can both weaken metal-oxygen bonds and reduce O2.V Formation energy, thereby inducing O V Generate. Simultaneously, O V It can serve as an electron-capturing center and additional adsorption site to promote catalytic reactions. Figure 3 X-ray photoelectron spectroscopy (XPS) showed that, judging from the peak shape, the modified catalyst LSKM... + 、LSKMFe + The high ROS ratio indicates that this series of catalysts theoretically possesses good catalytic performance.

[0048] Experiment Example 2: CO Oxidation Performance Test 1. Experimental Methods The performance of a catalyst (100 mg, 20-80 mesh) in the CO oxidation reaction was evaluated using a fixed-bed quartz microreactor. The reaction conditions were: 1% CO, 10% O2 / N2 (total flow rate in the pipeline was 100 mL / min, air pressure was 1.35 atm), temperature was increased to 500 °C (heating rate 10 °C / min), and the CO and CO2 concentrations at the outlet were measured. The CO conversion rate was calculated according to the following equation:

[0049] Among them, X CO C represents the carbon monoxide conversion rate. CO and These are the concentrations of carbon monoxide and carbon dioxide at the outlet, respectively (all carbon elements in the gas originate from carbon monoxide).

[0050] The reaction rate k (μmol / g·s) can be calculated by assuming ideal gas behavior:

[0051] Among them, X CO F represents the carbon monoxide conversion rate. CO (μmol / s) is the molar gas flow rate of carbon monoxide, and W (g) is the mass of the catalyst in the fixed-bed reactor.

[0052] CO2 Selectivity: The CO2 selectivity of the catalyst was evaluated using the flue gas-to-TPO method. The catalyst and flue gas were mixed at a 10:1 ratio, and the reaction gas was 10% O2 / Ar (50 mL / min). The temperature was increased to 600℃ at a rate of 10℃ / min, while the composition and concentration of the outlet gas were simultaneously measured. The formula for calculating CO2 selectivity is as follows:

[0053] in, and C COThese represent the concentrations of carbon dioxide and carbon monoxide detected at the outlet, respectively (all carbon elements originate from the smoke and dust in the sample).

[0054] 2. Test Results (1) By Figure 4 Modified catalysts a and b exhibit excellent CO catalytic activity. Specifically, as temperature increases, the CO concentration gradually decreases, while the CO2 concentration and conversion rate continuously increase. This indicates that the catalyst can effectively catalyze the conversion of CO to CO2 even at low temperatures. LSKM + With LSKMFe + The CO conversion rates reached 90% at 237℃ and 221℃, respectively, and further exceeded 94% and 96% at 250℃. Under the same catalytic conditions, LSKMFe... + It exhibits higher conversion rate and faster catalytic rate (k≈96.3 μmol / g·s), and its CO catalytic activity is significantly better than LSKM. + This indicates that Fe doping plays a key role in promoting the low-temperature CO oxidation reaction of La-Mn-based modified catalysts, effectively reducing the activation energy required for catalysis and enhancing catalytic activity.

[0055] (2) By Figure 4 Modified catalysts c and d exhibit excellent catalytic activity and satisfactory CO2 selectivity. The peak signals for both CO and CO2 significantly increase at temperatures exceeding 300°C. With increasing temperature, LSKM... + and LSKMFe + The CO2 selectivity continued to improve, exceeding 96% at 328℃ and 337℃, respectively. LSKM + It exhibits a lower ignition temperature, while LSKMFe + It exhibits a faster catalytic rate and a lower combustion completion temperature. The above series of characterization results show that the macroporous structure enhances the catalytic performance of flue gas, while Fe doping improves the catalytic rate.

[0056] , Experiment Example 3: Test of Oxidation Performance of Smoke Dust 1. Experimental Methods Thermogravimetric analysis (TGA) was used, with carbon black simulating flue gas. The catalyst and carbon black were mixed at a 1:2 ratio, and the temperature was increased to 800℃ at a rate of 10℃ / min under air atmosphere. To scientifically quantify the catalytic effect of the catalyst, a Tg was introduced. 10 T 50 T 90 and the Tmax index, where T 10 Considered as the ignition temperature of carbon black, T 90 Tmax is the temperature at which combustion is completed, while Tmax is the temperature at which catalytic activity is at its highest.

[0057] 2. Results The results are as follows Figure 5 As shown in Table 1, LSKM + T 10 =300.7℃, T 50 =445.2℃, T 90 =556.7℃; LSKMFe + T 10 =438.5℃, T 50 =518.1℃, T 90 =556.3℃, compared to unmodified LM(T) 10 =505.1℃, T 50 =601.8℃, T 90 =629.7℃), the ignition temperature is reduced by 100-200℃, and stable catalytic performance and high catalytic rate are maintained throughout the heating stage. LSM + / Ag and LSM + / Pt can lower the ignition temperature of carbon black, but LSM + / Pt's T 50 and T 90 The value indicates that its high-temperature catalytic efficiency is limited, which may be related to the high-temperature deactivation of Pt. In summary, the method of this invention significantly improves the catalytic activity of carbonate-prepared catalysts for flue gas. Among them, LSKM... + and LSKMFe + It exhibits the best catalytic performance, and its overall catalytic performance in flue gas even surpasses that of LSM. + / Ag and LSM + / Pt.

[0058] Table 1 Catalytic performance of flue gas (catalyst and carbon black are loosely mixed in a 1:2 ratio)

[0059] LSKM was measured through fitting calculation. + and LSKMFe + T when mixed with smoke and dust 10 T 50 and T 90 Values. Table 2 compares the prepared modified catalyst with typical exhaust gas catalysts. The results show that LSKM + and LSKMFe + It has excellent catalytic activity for flue gas combustion, meeting the purification requirements of particulate matter (PM) in exhaust gas after-treatment systems.

[0060] Table 2 Comparison of catalytic activity between modified catalysts and conventional catalysts

[0061] [1] Liu C, Nie W, Luo C, et al. Improvement of purificationperformance of perovskite exhaust catalysts for underground diesel vehiclesby doping with Enteromorpha. Energy. 2024; 313: 134039. [2] Niu R, Li C, Guo Q, et al. Boosting catalytic combustion ofdiesel soot particles over potassium-promoted CoMn-Co3O4dual spinel structurecatalyst. Appl. Catal., B. 2024; 354, 124142. [3] Niu R, Zhang C, Liu P, et al. Constructing asymmetric active Fe 3+ -O V -Mn 4+ sites at the Fe2O3-MnO2interface for low-temperature soot combustion.Appl. Catal. B Environ. 2024; 358: 124365. [4] Gao S, Fu Y, Zhang X, et al. Hierarchical porous Na x Co y CeO δ catalysts: Facile preparation and excellent catalytic performance for sootcombustion. Appl. Catal. B Environ. 2025; 365: 124919. [5] Xu H, Zeng L, Cui L, et al. In-situ generation of platinumnanoparticles on LaCoO3 matrix for soot oxidation. J.Rare Earths. 2022; 40(6): 888-896. The above embodiments are merely preferred embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. Any changes, substitutions, modifications, etc., made by those skilled in the art without departing from the spirit and essence of the present invention should be within the protection scope of the present invention.

Claims

1. A doped non-noble metal perovskite catalyst suitable for use in a multi-fuel engine, characterized in that, The doped non-noble metal perovskite catalyst takes La as A-site metal and Mn as B-site metal, introduces Sr and K elements in the A-site, the molar ratio of Sr and K is 1:1, introduces Fe element in the B-site, and the expression of the perovskite catalyst is La 1-x-y Sr x K y Mn 1-z Fe z O3, wherein 0.05<=x<=0.2, 0.05<=y<=0.2, 0<=z<=0.2, and 0.1<=x+y<=0.

4.

2. The doped non-noble metal perovskite catalyst according to claim 1, characterized in that, The doped non-noble metal perovskite catalyst is a three-dimensional porous structure when z=0, with an average pore size of 0.3-0.8 μm, and the Sr and K elements are uniformly distributed in the perovskite lattice.

3. The doped non-noble metal perovskite catalyst according to claim 1, characterized in that, The doped non-noble metal perovskite catalyst is a honeycomb-like macroporous structure when 0 4. A method for preparing the doped non-noble metal perovskite catalyst according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: S1: weigh the carbonates of La, Mn, Sr, K and Fe according to the stoichiometric ratio shown in the expression, dissolve in deionized water, and stir until uniformly dispersed; add citric acid equal to the total number of moles of metal ions, ultrasonic treatment until the citric acid is completely dissolved, to obtain a clear mixed solution; S2: add an alkaline solution to the clear mixed solution, adjust the pH value of the system to 7-8, and continue stirring until a viscous gel-like precursor is formed; S3: dry the viscous gel-like precursor to obtain a solid precursor; S4: perform two-step calcination on the solid precursor under an air atmosphere; the first step is to heat at 2-5 ℃ / min to 350-450 ℃, and keep the temperature for 1-3 hours; the second step is to heat at 3-7 ℃ / min to 650-750 ℃, and keep the temperature for 2-4 hours, and then naturally cool down, to obtain the doped non-noble metal perovskite catalyst.

5. The preparation method according to claim 4, characterized in that, The ultrasonic treatment in S1 is 300-500 W for 15-30 min.

6. The preparation method according to claim 4, characterized in that, The alkaline solution in S2 is an ammonia solution with a mass fraction of 20%-30%.

7. The preparation method according to claim 4, characterized in that, The drying temperature in S3 is 65-75 ℃.

8. The production method according to claim 4, characterized by, The air atmosphere in S4 is air with a flow rate of 40-60 mL / min.

9. Use of the doped non-noble metal perovskite catalyst according to any one of claims 1 to 3, characterized in that, The catalyst is applied to engine exhaust purification.

10. Use according to claim 9, characterized in that, The exhaust purification is the purification of smoke and carbon monoxide in the exhaust of a fuel engine or an internal combustion engine.

Images