Coal gasification coarse slag supported metal oxide catalyst, preparation method and application

Abstract

The present application belongs to the technical field of supported metal oxide, and particularly relates to a coal gasification coarse slag supported metal oxide catalyst, a preparation method and application. The preparation method comprises the following steps: (1) firstly, the coal gasification coarse slag is dried, rubbed and sieved to obtain coal gasification coarse slag particles as a catalyst carrier; (2) the coal gasification coarse slag particles obtained in step (1) are mixed with a precursor solution, stirred and dried, and then placed in a furnace to be calcined under an air atmosphere to obtain a supported oxide catalyst. The present application realizes the reuse of coal gasification coarse slag (CGCS) by loading metal oxide on the coal gasification coarse slag, reduces the cost, realizes the reuse of waste, and simultaneously, the method is simple in preparation, the obtained denitration catalyst has good denitration activity and nitrogen selectivity, the material is safe, the price is low, and has wide application potential.

Description

Technical Field

[0001] This invention belongs to the field of coal gasification coarse slag supported metal oxide technology, specifically relating to a coal gasification coarse slag supported metal oxide catalyst, its preparation method and application. Background Technology

[0002] In recent years, the emissions of pollutants from the cement industry have remained significant, especially NOx. x The emissions of pollutants have become a major source of pollution in cement kilns, making denitrification of these kilns an urgent priority. Currently, denitrification methods in cement kilns primarily utilize selective non-catalytic reduction (SNCR) technology, supplemented by selective catalytic reduction (SCR) technology. SCR, with its superior denitrification efficiency, has gradually become a research hotspot and represents the next direction for denitrification in the cement industry. However, the adoption rate of SCR technology in the cement industry is low. The catalysts are mainly vanadium-based, and vanadium is toxic. Furthermore, SCR faces problems such as poisoning and high cost during use.

[0003] Coal gasification slag (CGS) is generally divided into coarse coal gasification slag (CGCS) and fine coal gasification slag (CGFS). It is a byproduct of the coal gasification process and needs to be treated as an industrial waste. The current disposal methods, such as open-air dumping and landfilling, still face many problems.

[0004] Furthermore, pure metal oxides, when used as denitrification catalysts, have limitations in both denitrification efficiency and N2 selectivity. They are also prone to agglomeration during preparation, requiring processes such as pressing into blocks and then crushing, resulting in low yields. Therefore, it is necessary to combine them with appropriate supports. Further research is needed on how to combine them with coal gasification slag to obtain highly efficient catalysts. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a coal gasification coarse slag supported metal oxide catalyst, its preparation method, and its application. This invention enables the reuse of coal gasification coarse slag (CGCS) by supporting metal oxides on it, reducing costs and achieving waste recycling. Furthermore, the method is simple to prepare, and the resulting denitrification catalyst exhibits good denitrification activity and nitrogen selectivity. The materials are safe, inexpensive, and have broad application potential.

[0006] To achieve the above objectives, on the one hand, the present invention provides a method for preparing a coal gasification coarse slag supported metal oxide catalyst, wherein the metal oxide is an iron-based oxide or a manganese-based oxide, and the preparation method includes the following steps:

[0007] (1) First, the coarse coal gasification slag is dried, crushed and sieved to obtain coarse coal gasification slag particles, which are used as catalyst carriers;

[0008] (2) The coal gasification coarse slag particles obtained in step (1) are mixed with Fe(NO3)3 precursor solution, stirred and dried, and then placed in a furnace for calcination in air atmosphere to obtain a supported iron-based oxide catalyst.

[0009] The coal gasification coarse slag particles obtained in step (1) are mixed with Mn(NO3)2 precursor salt solution to obtain a supported manganese-based oxide catalyst by the above method.

[0010] Among them, for supported iron-based oxide catalysts, the total mass of the coal gasification slag on the support is 5%-20%, and the loading percentage is calculated as Fe2O3.

[0011] For supported manganese-based oxide catalysts, the loading percentage on the coal gasification coarse slag is 3%-7% by mass, based on the total mass of the supported coal gasification coarse slag and calculated as MnO2.

[0012] A further improvement to this scheme is that the calcination temperature of the supported manganese-based oxide is 550℃, and the calcination temperature of the supported iron-based oxide is 550℃.

[0013] A further improvement to this scheme is that the coal gasification coarse slag comprises the following components by mass fraction: SiO2 17.2%,

[0014] Al2O3 8.51%, CaO 3.8%, Fe2O3 6.5%, MgO 1.86%, Na2O 1.8%, K2O 0.21%, SO33.82%, MnO 0.31%.

[0015] Further improvements to this scheme include a 15% mass percentage loading of the supported iron-based oxide catalyst onto the coal gasification slag, and a 5% mass percentage loading of the supported manganese-based oxide catalyst onto the coal gasification slag.

[0016] A further improvement to this scheme, the preparation method of supported iron-based oxides, is as follows:

[0017] (1) First, the coarse coal gasification slag is dried in an oven at 105℃ for 12 hours, crushed, and passed through a 40-60 mesh square hole sieve to obtain coarse coal gasification slag particles, which are used as catalyst carriers.

[0018] (2) Weigh 3.7950g of ferric nitrate nonahydrate Fe(NO3)3·9H2O solid powder and pour it into a beaker. Add deionized water, stir, and let stand for 2h to obtain Fe(NO3)3 precursor salt solution (the concentration of Fe(NO3)3 in the precursor salt solution is not required here. The amount of deionized water added later will not affect the final performance. As long as the distribution is uniform, the subsequent drying is fine). Weigh 5g of the coal gasification coarse slag particles from step (1) and mix them with the Fe(NO3)3 precursor salt solution. Stir mechanically for 3h, dry in a forced-air drying oven at 80℃ for 5h, and then at 110℃ for 12h. Place the dried particles in a tube furnace, heat at a rate of 10℃ / min, and calcine at 550℃ in an air atmosphere for 3h. After naturally cooling to room temperature, the catalyst preparation is complete. A 15% mass fraction Fe-based oxide catalyst is obtained. Weigh ferric nitrate nonahydrate Fe(NO3)3·9H2O in the same way to prepare the corresponding mass fraction Fe-based oxide catalyst.

[0019] A further improvement to this scheme, the preparation method of supported manganese-based oxides, is as follows:

[0020] (1) First, the coarse coal gasification slag is dried in an oven at 105℃ for 12 hours, crushed, and passed through a 40-60 mesh square hole sieve to obtain coarse coal gasification slag particles, which are used as catalyst carriers.

[0021] Weigh 1.029g of 50wt.% Mn(NO3)2 aqueous solution and pour it into a beaker. Add deionized water, stir, and let stand for 2h to obtain a precursor salt solution (the concentration of the Mn(NO3)2 precursor salt solution is not required here. The amount of deionized water added later will not affect the final performance. As long as the dissolution is complete, drying can be carried out later). Weigh 5g of the coal gasification coarse slag particles obtained in step (1) and mix them with the Mn(NO3)2 precursor salt solution after standing. Stir mechanically for 3h. Dry in a forced-air drying oven at 80℃ for 5h and at 110℃ for 12h. Place the dried particles in a tube furnace and calcine at 550℃ in air atmosphere for 3h at a heating rate of 10℃ / min. After natural cooling to room temperature, the catalyst preparation is completed. The loading percentage is based on MnO2 and the support is the total mass. A 5% mass fraction Mn-based oxide catalyst is obtained. The corresponding mass fraction Mn-based oxide catalyst is prepared by taking Mn(NO3)2 solution in the same way.

[0022] On the other hand, the present invention provides, in addition to the above-mentioned preparation method, a coal gasification coarse slag supported metal oxide.

[0023] Furthermore, this invention provides the application of the aforementioned coal gasification coarse slag supported metal oxide in the field of denitrification.

[0024] Further improvements to this scheme include a denitrification temperature of 200℃-350℃ for unloaded iron-based oxides and a denitrification temperature of 150℃-300℃ for unloaded manganese-based oxides.

[0025] Further improvements to this scheme include a denitrification temperature of 300℃ for unloaded iron-based oxides and a denitrification temperature of 150-200℃ for unloaded manganese-based oxides.

[0026] The beneficial effects of this invention are as follows:

[0027] (1) Coal gasification coarse slag (CGCS) has a well-developed pore structure and a certain mechanical strength, making it suitable for loading active components of metal oxides. This invention selects coal gasification coarse slag and loads iron or manganese-based oxides onto it, achieving the reuse of the slag. The unique structure of the slag endows it with significant adsorption capacity and synergistic effects with the loading of metal oxides. A loading percentage of 3%-7% or 5%-20% on the slag achieves a denitrification effect similar to that of pure metal oxides. Furthermore, due to the special characteristics of cement flue gas—high dust concentration, large temperature fluctuations (generally due to fluctuations in rotary kiln operating conditions leading to large fluctuations in C1 outlet temperature), and sulfur content—pure metal catalysts suffer from unstable structures, resulting in severe wear and pore blockage. The well-developed pore structure and mechanical strength of the coal gasification coarse slag can improve this problem.

[0028] (2) The present invention uses the impregnation method to prepare CGCS-xFe catalyst and optimizes the loading of iron-based oxides. At the denitrification temperature of 300℃, CGCS-15Fe has extremely high denitrification activity and CGCS-20Fe has extremely high N2 selectivity.

[0029] (3) The present invention also utilizes impregnation method to prepare CGCS-Mn catalyst and optimizes the loading of manganese-based oxides. At 200℃, the denitrification efficiency of CGCS-5Mn reaches 90%, and the N2 selectivity of CGCS-7Mn reaches 99% at 150℃.

[0030] (4) In terms of sulfur poisoning resistance, although the denitrification efficiency of CGCS-15Fe decreases after SO2 is introduced, the effect of medium and high temperature activity is relatively small. It can still maintain high denitrification performance after SO2 is turned off. It has strong resistance to sulfur poisoning and solves the problem of poor resistance to poisoning of simple metal oxide catalysts.

[0031] (5) Although unsupported metal oxides have excellent denitrification activity and N2 selectivity, they are prone to obvious sintering and agglomeration. The present invention obtains Fe and Mn-based metal oxides, which are simple to prepare. The adsorption effect of the coal gasification slag avoids the problems of agglomeration and sintering during the preparation process. The yield is high, and there is no need to press into blocks and then crush them. At the same time, the cost is low and the use is safe. It can solve the problems of cumbersome preparation, toxicity, high price and inconvenience of promotion of denitrification catalysts in the current industry. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 Denitrification activity test flowchart;

[0034] Figure 2 Denitrification efficiency of different CGCS;

[0035] Figure 3 Denitrification efficiency of different carriers loaded with 5% Fe;

[0036] Figure 4 Denitrification efficiency (a) and N2 selectivity (b) of CGCS-xFe with different Fe loadings at different temperatures;

[0037] Figure 5 Anti-toxicity test of CGCS-15Fe at different test temperatures;

[0038] Figure 6 SEM images of CGCS at different magnifications: (a)-(f) correspond to magnifications of 100x, 500x, 1000x, 2000x, 5000x and 10000x respectively;

[0039] Figure 7 XRD patterns of CGCS blank and xFe loaded;

[0040] Figure 8 Denitrification efficiency (a) and N2 selectivity (b) of CGCS-xMn with different Mn-based oxide loadings at different temperatures;

[0041] Figure 9 CGCS-xMn(a) XRD patterns with different loading levels;

[0042] In the diagram, 1 is the NO tube, 2 is the O2 tube, 3 is the NH3 tube, 4 is the Ar tube, 5 is the SO2 tube; 6 is the proton flow meter; 7 is the gas mixing device; 8 is the quartz tube; 9 is the tubular resistance furnace; 10 is the thermocouple; 11 is the flue gas analyzer; and 12 is the temperature controller. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0044] The process flow of the catalyst activity evaluation device is as follows: Figure 1 As shown.

[0045] After being depressurized by a pressure reducing valve, the five gases enter the gas mixing device at a set flow rate via a proton flow meter, and the catalyst is filled into a quartz tube. Quartz wool is placed on both sides of the catalyst to prevent it from being carried away by the gas flow. A temperature control device works in conjunction with the tube furnace to control the temperature. The reacted gases flow through a phosphoric acid washing bottle to remove moisture and excess NH3, and then enter a flue gas analyzer until venting is complete. The flow rates are: O2 30 ml / min, NO 25 ml / min, NH3 25 ml / min, Ar 170 ml / min, total flow rate 250 ml / min, catalyst loading 1.5 ml, and space velocity 10000 h⁻¹. -1 During the experiment, each temperature window was maintained for 20 minutes.

[0046] Denitrification efficiency (η%) and nitrogen selectivity (S) N2 These are two important indicators for evaluating the denitrification performance of catalysts.

[0047]

[0048] In the above two formulas, η represents the NO conversion rate (%), and C NO.in and C NO，out These represent the inlet and outlet concentrations of NO (ppm) and C, respectively. NH3,in C NO2,out C N2O,out These represent the inlet concentration (ppm) of NH3, and the outlet concentrations (ppm) of NO2 and N2O, respectively. N2 Represents nitrogen selectivity (%).

[0049] All raw materials used in this invention are commercially available. Manganese nitrate is analytical grade and comes from Maclean's reagents. Ferric nitrate is analytical grade and comes from Sinopharm Chemical Reagent Co., Ltd. The gases used in the experiment come from Anqiu Heng'an Gas Factory.

[0050] I. Fe-based metal oxide catalyst supported on coal gasification coarse slag and its denitrification performance

[0051] Example 1: Selection of Coal Gasification Coarse Slag (CGCS) Carrier

[0052] First, the carrier was screened, that is, loading tests were conducted on CGCS from three different sources, and the optimal carrier was selected. The three CGCS were designated as CGCS(Ⅰ), CGCS(Ⅱ), and CGCS(Ⅲ). The preparation methods are as follows, and their denitrification activities were tested under the same test conditions.

[0053] First, the coarse coal gasification slag (CGCS) is dried in an oven at 105℃ for 12 hours, crushed, and passed through a 40-60 mesh square hole sieve to obtain CGCS particles, which are used as catalyst carriers.

[0054] Figure 2 The figure shows the denitrification efficiency of different carriers in the state without any metal oxide loading (i.e., blank state). As can be seen from the figure, the three CGCSs themselves have certain denitrification activity, but the activity is relatively low. Even CGCS(Ⅰ), which has the highest denitrification efficiency, is only about 48% at 400℃. The denitrification efficiencies of CGCS(Ⅱ) and CGCS(Ⅲ) do not exceed 35% at the highest, and the temperature point of the highest denitrification efficiency is located at 300℃.

[0055] For standardization and comparison, and further screening, three types of CGCS were simultaneously loaded with 5% Fe and subjected to denitrification tests. Alternatively, each of the three CGCS types was loaded with 5% iron oxide, using the following loading methods.

[0056] (1) The specific preparation process of the supported iron-based catalyst is as follows: Weigh 0.2530g of ferric nitrate nonahydrate Fe(NO3)3·9H2O solid powder and pour it into a beaker. Add an appropriate amount of deionized water, stir, and let stand for 2h. Weigh 5g of CGCS and mix it with Fe(NO3)3 solution. Stir mechanically for 3h, dry in a forced-air drying oven at 80℃ for 5h, and then at 110℃ for 12h. Place the dried particles in a tube furnace, heat at a rate of 10℃ / min, and calcine in air at 550℃ for 3h. After naturally cooling to room temperature, the catalyst preparation is complete. A 1% mass fraction Fe catalyst (percentage based on Fe2O3, support is based on total mass) is obtained, denoted as CGCS-1Fe. CGCS-5Fe, CGCS-10Fe, CGCS-15Fe, and CGCS-20Fe are prepared using the same method.

[0057] Figure 3The denitrification efficiency of different carriers loaded with 5% Fe was shown. After loading with 5% Fe, the denitrification efficiency of all three carriers was improved compared to the blank sample, and the temperature point at which the highest denitrification efficiency was achieved was 300℃. Figure 8 In the study, CGCS(Ⅰ) achieved its highest denitrification efficiency at 400℃, combined with... Figure 3 It can be concluded that Fe-based oxides possess certain medium- and high-temperature denitrification activity. Among the three catalysts, CGCS(Ⅰ)-5Fe exhibits the highest denitrification efficiency. Therefore, CGCS(Ⅰ) will be used as an example in the following experiments. Unless otherwise specified, CGCS in the following text refers to CGCS(Ⅰ).

[0058] Example 2: Effect of different iron loading on the denitrification performance of CGCS-xFe

[0059] Figure 4 (a) The denitrification efficiency of CGCS-xFe with different Fe loadings at different temperatures. As shown in the figure, the denitrification efficiency of unloaded CGCS is lowest below 300℃. With increasing Fe loading, the denitrification efficiency gradually increases. When the Fe loading reaches 15%, the denitrification efficiency decreases with increasing Fe loading, presumably because the lower Fe loading concentration fails to saturate the active sites on the CGCS surface. However, when the loading reaches 20%, the active components on the CGCS surface agglomerate or cover, leading to a reduction in the number of active sites and affecting the contact between the active components and the flue gas, thus reducing the denitrification efficiency. It can be seen that the optimal Fe loading on CGCS is 15%. Furthermore, by gradually increasing the Fe loading from the blank sample, a phenomenon can be observed: the temperature point with the highest denitrification efficiency gradually decreases from 400℃ to 300℃, indicating that the optimal denitrification temperature window for CGCS after Fe loading is located in the mid-to-high temperature range. Figure 4 (b) It can be seen that the average N2 selectivity is above 94%, gradually increasing with increasing temperature and loading within the range of 150-300℃. At 300℃, all five catalysts exhibit the highest N2 selectivity. Unlike the denitrification efficiency, the N2 selectivity of CGCS-15Fe at 300℃ is lower than that of CGCS-20Fe. In summary, at 300℃, CGCS-15Fe has the highest denitrification activity, but CGCS-20Fe has the highest N2 selectivity.

[0060] Example 3: Test of CGCS-15Fe's resistance to sulfur poisoning

[0061] Almost all denitration catalysts are designed with SO2 poisoning in mind. The main mechanism by which SO2 causes catalyst deactivation is that SO2 readily reacts with NH3 to form ammonium sulfate or ammonium bisulfate. These ammonium salts easily deposit on the surface of the denitration catalyst, clogging channels and pores, reducing the contact between the active components and the gas, thus leading to a decrease in denitration efficiency, i.e., catalytic "deactivation". Therefore, resistance to sulfur poisoning has become a crucial indicator for denitration catalysts. The test conditions were an SO2 concentration of 500 ppm (during use) and the balance gas was still high-purity argon. Sulfur resistance experiments were conducted on CGCS-15Fe at 300℃, and the results are as follows... Figure 5 As shown, when SO2 gas was introduced into the simulated gas, the denitrification efficiency decreased, from a maximum of 76% to approximately 40%. However, after the SO2 was turned off, the denitrification activity of CGCS-15Fe gradually recovered at 300℃, and the final denitrification efficiency recovered to approximately 68%, demonstrating strong resistance to sulfur poisoning.

[0062] Example 4: Characterization and Analysis of CGCS-xFe

[0063] (1) Physicochemical characteristics and microstructure analysis of the carrier

[0064] Table 1. Analysis of the main chemical composition of CGCS from different sources

[0065]

[0066] As shown in Table 1, the coarse slag from coal gasification is mainly composed of SiO2, Al2O3, CaO, Fe2O3 and residual carbon. Among them, CGCS(Ⅰ) has a high loss on ignition, which is because it has a large amount of residual carbon and a rich carbon skeleton structure, which also meets the requirements of catalyst carrier: porous and large specific surface area. Figure 6 Microscopic images of CGCS(Ⅰ) at different magnifications show that the inorganic components exist in both fully molten and partially molten states, and are divided into smooth and rough surfaces. CGCS(Ⅰ) possesses a well-developed pore structure, mainly due to the disappearance of volatiles in the pyrolysis section of the coal gasification slag and the reaction of the gasifying agent through the coal coke pores during the gasification stage, which creates pores. However, because the residual carbon in the coarse slag has a short residence time in the gasifier, its pore structure and surface area are smaller than those of the residual carbon in the fine coal gasification slag. At high temperatures, the inorganic components in the coal gasification slag tend to form spherical glassy substances due to surface tension. From a morphological perspective, the gasification coarse slag generally exhibits three structures: dense and smooth spherical particles, dense and smooth irregular blocky and flaky particles, and porous irregular flocculent particles. Relevant literature also provides analytical conclusions, namely that the main components of spherical and irregular blocky and flaky particles are mainly O, Si, Al, Ca, and Fe, containing some residual carbon, while porous flocculent particles are mainly composed of C.

[0067] (2) Phase analysis of the support and catalyst

[0068] Figure 7 The XRD patterns are shown for a blank CGCS sample and samples loaded with 1%, 5%, 10%, 15%, and 20% Fe, respectively. The figures show a distinct peak at 2θ angles between 20° and 30°, indicating the presence of almost no crystalline phase and a large amount of amorphous phase. The inherent crystal form of inorganic minerals in coal undergoes intense high-temperature oxidation, melting, and rapid cooling to solidify into larger-particle glassy substances. The main mineral phase is amorphous aluminosilicate, primarily composed of silicon dioxide, similar to the composition of clinker. Figure 4 It is known that increasing the Fe loading is beneficial to improving activity. CGCS-15Fe exhibits the highest denitrification efficiency at 300℃, with significant activity at medium and high temperatures. XRD analysis did not reveal a distinct Fe2O3 crystalline phase in CGCS(1-10Fe), indicating that the active components are highly dispersed on the support surface. When the Fe loading is 15%, the active components have just begun to crystallize, at which point the amorphous phase content is highest and dispersed on the CGCS surface, which explains the highest denitrification efficiency of CGCS-15Fe. When the Fe loading reaches 20%, the denitrification efficiency begins to decline because the active components agglomerate, forming a distinct crystalline phase that blocks pores, leading to a reduction in active sites. II. Mn-based metal oxide catalysts supported on coal gasification coarse slag and their denitrification performance

[0069] Example 5: Effect of different manganese loading on the denitrification performance of CGCS-xMn

[0070] The specific preparation process of the supported manganese-based catalyst is as follows:

[0071] Coal gasification coarse slag (CGCS) was dried in an oven at 105℃ for 12 hours, crushed, and passed through a 40-60 mesh square hole sieve to obtain CGCS particles, which were used as catalyst carriers.

[0072] Weigh 0.2058 g of Mn(NO3)2 solution (50 wt.% in H2O) and pour it into a beaker. Add an appropriate amount of deionized water, stir, and let stand for 2 h to obtain a precursor salt solution. Weigh 5 g of the above-obtained CGCS particles and mix them with the Mn(NO3)2 precursor salt solution. Stir mechanically for 3 h. Dry in a forced-air drying oven at 80℃ for 5 h and then at 110℃ for 12 h. Place the dried particles in a tube furnace and calcine at 550℃ in air atmosphere at a heating rate of 10℃ / min for 3 h. After naturally cooling to room temperature, the catalyst preparation is complete. A 1% mass fraction Mn catalyst (loading percentage is based on MnO2, and the support is the total mass) is obtained, denoted as CGCS-1Mn. CGCS-1Mn, CGCS-3Mn, CGCS-5Mn, and CGCS-7Mn are prepared using the same method.

[0073] The denitrification activity of CGCS loaded with 1%, 3%, 5%, and 7% Mn oxide was tested and analyzed. Figure 8 The denitrification efficiency and N2 selectivity of CGCS-xMn with different Mn loadings at different temperatures were investigated.

[0074] As shown in the figure, the denitrification activity generally increases with increasing Mn loading. The highest denitrification efficiency (approximately 90%) is achieved when the loading reaches 5%, but decreases when the loading reaches 7%. This is presumably due to the aggregation of active components on the CGCS surface, leading to pore blockage, reduced active sites, and decreased reaction opportunities between flue gas and active components. At 150℃, compared to the CGCS blank sample, the denitrification activity of all four catalysts is significantly improved. At 200℃, CGCS-1Mn, CGCS-5Mn, and CGCS-7Mn all reach the highest denitrification efficiency, indicating good low-temperature activity. The denitrification efficiency gradually decreases with increasing temperature. When testing N2 selectivity, the N2 selectivity increases with increasing loading. CGCS-7Mn reaches 99% at 150℃. Analysis suggests that high loading leads to aggregation, resulting in an irregular CGCS surface structure with numerous defects, leading to higher N2 selectivity. With increasing temperature, the N2 selectivity of all catalysts decreases. All four catalysts exhibited optimal performance at 150℃, indicating that CGCS loaded with Mn demonstrates excellent N2 selectivity at low temperatures. Different loading amounts correspond to different denitrification performances, with CGCS-5Mn exhibiting the highest denitrification efficiency and CGCS-7Mn exhibiting the highest N2 selectivity.

[0075] Example 6: Characterization and Analysis of CGCS-xMn

[0076] Figure 9 The XRD patterns of different manganese loadings are shown in the figure. As can be seen from the figure, none of the four catalysts showed significant MnO. x The formation of crystals indicates that manganese oxides are uniformly dispersed on the support surface or exist in an amorphous state. CGCS-loaded Mn exhibits relatively high low-temperature activity, achieving denitrification efficiencies of over 50% at 150℃ and approaching 90% at 200℃, demonstrating significant low-temperature activity. After loading Mn onto CGCS, electron transfer occurs between Fe in the CGCS and the loaded Mn, forming a crystal structure that can be classified as (Mn... 0.983 Fe 0.017 The formation of a new phase of 2O3 improves the redox performance of the catalyst. Furthermore, the formation of this new phase indicates a strong interaction between the active component and the support.

[0077] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the invention should also be covered within the protection scope of the invention. Therefore, the protection scope of the invention should be determined by the scope of the claims.

Claims

1. The application of a coal gasification coarse slag supported metal oxide catalyst in the field of denitrification, characterized in that, The metal oxide is an iron-based oxide, and the catalyst preparation method includes the following steps: (1) First, the coarse coal gasification slag is dried, crushed and sieved to obtain coarse coal gasification slag particles, which are used as catalyst carriers; (2) The coal gasification coarse slag particles obtained in step (1) are mixed with Fe(NO3)3 precursor solution, stirred and dried, and then placed in a furnace and calcined at 550°C in air atmosphere to obtain a supported iron-based oxide catalyst. For supported iron-based oxide catalysts, the total mass of the coal gasification slag on the support is 15%, and the loading percentage is calculated as Fe2O3. The denitrification temperature is 300℃.

2. The application according to claim 1, characterized in that, The preparation method of supported iron-based oxide catalysts is as follows: (1) First, the coarse coal gasification slag is dried in an oven at 105°C for 12 hours, crushed, and passed through a 40-60 mesh square hole sieve to obtain coarse coal gasification slag particles, which are used as catalyst carriers. (2) Weigh 3.7950 g of ferric nitrate nonahydrate Fe(NO3)3·9H2O solid powder and pour it into a beaker. Add deionized water, stir, and let stand for 2 h to obtain Fe(NO3)3 precursor salt solution. Weigh 5 g of the coal gasification coarse slag particles from step (1) and mix them with the Fe(NO3)3 precursor salt solution. Stir mechanically for 3 h, dry in a forced-air drying oven at 80°C for 5 h, and then dry at 110°C for 12 h. Place the dried particles in a tube furnace, heat at a rate of 10°C / min, and calcine at 550°C in air atmosphere for 3 h. After naturally cooling to room temperature, the catalyst preparation is complete. A 15% mass fraction Fe-based oxide catalyst is obtained.

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