Metal sulfate modified supported aluminum-based denitration catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalytic denitration, in particular to a metal sulfate modified supported aluminum-based denitration catalyst and a preparation method and application thereof.The preparation method comprises the following steps that 1, copper salt and manganese salt are dissolved in deionized water according to a certain molar ratio, gamma-Al2O3 is added into the mixed solution, and magnetic stirring is conducted; 2) evaporating the solvent in an oil bath, and drying in a drying oven; and (3) after the drying is finished, grinding a solid sample, putting the solid sample into a crucible, roasting in a muffle furnace, cooling and grinding a final product to obtain the CuSO4-MnSO4 / Al2O3 catalyst, marking the catalyst as xCuSO4-yMnSO4 / Al2O3, and respectively representing the loading capacities of CuSO4 and MnSO4 and the unit as mmol / g gamma-Al2O3. The denitration activity of the catalyst prepared by the preparation method disclosed by the invention is greater than 80% in a range of 300-500 DEG C.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalytic denitration, and in particular to a metal sulfate modified supported aluminum-based denitration catalyst, a preparation method and application thereof. BACKGROUND

[0002] Nitrogen oxides (NO x ) are produced by fossil fuel combustion and are one of the main atmospheric pollutants, and their massive emission can cause acid rain, ozone layer depletion, photochemical smog and many other environmental problems. Ammonia selective catalytic reduction technology (NH3-SCR) is currently the most widely used technology for removing NO x from stationary sources, and can effectively remove NO x . In this field, V2O5-WO3 / TiO2 catalysts have been commercialized and have excellent denitrogenation efficiency in the range of 300-400℃, but still have defects such as narrow catalytic activity temperature window, poor resistance to alkali metal poisoning and certain biological toxicity. Therefore, there is a broad research prospect for developing new catalysts with high catalytic performance and environmental friendliness.

[0003] Flue gas contains a certain amount of sulfur oxides (SO x ), which will usually accumulate on the surface of NH3-SCR catalysts and form bulk phase sulfates, resulting in poisoning of active sites and degradation of NH3-SCR performance. However, a large number of studies have shown that doping an appropriate amount of sulfur can help increase the surface acidity of the catalyst, which is conducive to ammonia adsorption, and in high-temperature environments, it can even promote the SCR process. Among the many studies on metal sulfate catalysts, copper-based and manganese-based catalysts have been widely concerned due to their low cost and adjustable physicochemical properties. Single copper sulfate (CuSO4)-based catalysts exhibit significant catalytic performance in NH3-SCR reactions, but have the disadvantage of poor high-temperature activity. To address this problem, the present application modifies the catalyst by introducing manganese sulfate (MnSO4·H2O) and adjusting the surface acidity of the catalyst to improve the catalytic activity and resistance to SO2 poisoning, so that the catalyst can maintain good NO x conversion rate in complex flue gas environments. SUMMARY

[0004] The present application aims to provide a metal sulfate modified supported aluminum-based denitration catalyst and a preparation method and application thereof. The CuSO4-MnSO4 / Al2O3 catalyst is prepared by a co-impregnation method, and the ratio of copper (Cu) and manganese (Mn) in the catalyst is optimized to obtain a new catalyst with a wide temperature window at medium-high temperature conditions. The results of the catalysis show that the structure and morphology of Cu species and Mn species in the catalyst and the synergistic effect of Cu and Mn in the catalyst have an important influence on the catalytic activity of the catalyst.

[0005] Specifically, the present application provides the following technical solutions:

[0006] A preparation method of a metal sulfate modified supported aluminum-based denitration catalyst, comprising the following steps:

[0007] (1) Dissolve copper salt and manganese salt in deionized water according to a certain molar ratio, add γ-Al2O3 to the mixed solution and magnetically stir;

[0008] (2) Dry the solvent in an oil bath and dry in an oven;

[0009] (3) After drying, grind the solid sample and place it in a crucible, calcine in a muffle furnace, and obtain the CuSO4-MnSO4 / Al2O3 catalyst after cooling and grinding the final product, and the catalyst is marked as xCuSO4-yMnSO4 / Al2O3, wherein x and y represent the loading amount of CuSO4 and MnSO4, respectively, in units of mmol / g γ-Al2O3, and x+y=0.6.

[0010] In the step (1), the total concentration of Cu 2+ and Mn 2+ in the solution is 0.6 mmol / g γ-Al2O3.

[0011] In the step (1), the copper salt includes CuSO4·5H2O, CuSO4·2H2O or CuSO4; and the manganese salt includes MnSO4·4H2O, MnSO4·H2O or MnSO4.

[0012] In the step (1), the magnetic stirring time is 1 h.

[0013] In the step (2), the solvent is dried in an oil bath at 110℃, and dried in an oven at 110℃ for 3 h.

[0014] In the step (3), the calcination temperature is 550℃, the calcination time is 3 h, and the heating rate is 2℃ / min.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] The present invention prepared a new catalyst 0.2CuSO4-0.4MnSO4 / Al2O3 for NH3-SCR in the medium and high temperature range through a co-impregnation method. The denitrification activity in the range of 300–500°C is greater than 80%. Experimental results show that there is a certain synergistic effect between Cu and Mn, and the intensity of this synergistic effect is related to the Cu / Mn ratio and the preparation method of the catalyst. The strongest synergistic effect is shown when the Cu / Mn ratio is 1:2. This synergistic effect can promote the high dispersion of active components on the support surface, thereby enhancing the catalyst surface's NO removal. x Adsorption and activation ability with NH3. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Denitrification activity of xCuSO4-yMnSO4 / Al2O3-550 catalysts with different Cu / Mn molar ratios. Activity test conditions: 500 ppm NH3, 500 ppm NO, 5% O2, total flow rate 200 mL / min, catalyst dosage 300 mg.

[0018] Figure 2 The denitrification activity of 0.2CuSO4-0.4MnSO4 / Al2O3-X catalysts calcined at different temperatures was tested under the following conditions: 500ppm NH3, 500ppm NO, 5% O2, a total flow rate of 200mL / min, and a catalyst dosage of 300mg.

[0019] Figure 3 The denitrification activity of 0.2CuSO4-0.4MnSO4 / Y catalysts under different supports was tested under the following conditions: 500ppm NH3, 500ppm NO, 5% O2, total flow rate 200mL / min, and catalyst dosage 300mg.

[0020] Figure 4 0.2CuSO4-0.4MnSO4 / Al2O 33 -550 catalyst has good resistance to sulfur and water poisoning at 400℃.

[0021] Figure 5 The X-ray diffraction (XRD) test results of the catalyst.

[0022] Specific implementation party

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1 Effect of different Cu / Mn molar ratios on the performance of xCuSO4-yMnSO4 / Al2O3-550 catalyst

[0025] CuSO4-MnSO4 / Al2O3 catalysts with different Cu / Mn molar ratios were prepared by co-impregnation method. First, CuSO4·5H2O and MnSO4·H2O were mixed at a certain molar ratio (n Cu :n Mn =1:1, 1:2 and 1:5, and control the Cu 2+ With Mn 2+ The total concentration is 0.6 mmol / gγ-Al2O3) dissolved in deionized water. γ-Al2O3 is added to the mixed solution and magnetically stirred for 1 hour. The solvent is then evaporated in an oil bath at 110°C and dried in an oven at 110°C for 3 hours. After drying, the solid sample is ground and placed in a crucible and calcined in a muffle furnace at 550°C for 3 hours (heating rate 2°C / min). The final product is cooled and ground to obtain a CuSO4-MnSO4 / Al2O3 catalyst. The catalyst is labeled xCuSO4-yMnSO4 / Al2O3-550, where x and y represent the loading amounts of CuSO4 and MnSO4, respectively, in mmol / gγ-Al2O3, and x+y=0.6.

[0026] like Figure 1 As shown, when the total metal sulfate loading on each catalyst is 0.6 mmol / g, the composite-supported catalysts exhibit a wider activity window compared to the single-loaded 0.6CuSO4 / Al2O3-550 and 0.6MnSO4 / Al2O3-550 catalysts. Furthermore, the ratio of Cu to Mn affects the catalytic performance. Among them, 0.2CuSO4-0.4MnSO4 / Al2O3-550 exhibits the best catalytic activity, achieving NO conversion rates exceeding 80% within the 300–500°C range.

[0027] Example 2 Effect of different calcination temperatures on the performance of 0.2CuSO4-0.4MnSO4 / Al2O3-X catalyst

[0028] CuSO4-MnSO4 / Al2O3 catalysts with different calcination temperatures were prepared by co-impregnation method. First, CuSO4·5H2O and MnSO4·H2O were mixed at a certain molar ratio (n Cu :n Mn =1:2, and control the Cu content in the solution 2+ With Mn 2+The total concentration was 0.6 mmol / g γ-Al2O3) was dissolved in deionized water. γ-Al2O3 was added to the mixed solution and magnetically stirred for 1 hour. The solvent was then evaporated in an oil bath at 110°C and dried in an oven at 110°C for 3 hours. After drying, the solid sample was ground and placed in a crucible and calcined in a muffle furnace at 350°C, 450°C, 550°C, 650°C, and 750°C for 3 hours (heating rate 2°C / min). The final product was cooled and ground to obtain CuSO4-MnSO4 / Al2O3 catalyst. The catalyst was labeled 0.2CuSO4-0.4MnSO4 / Al2O3-X (X = 350°C, 450°C, 550°C, 650°C, 750°C).

[0029] Depend on Figure 2 It can be seen that under the condition that the Cu / Mn molar ratio of each catalyst is 1:2, when the calcination temperature is in the range of 450–650°C, the activity of the 0.2CuSO4-0.4MnSO4 / Al2O3-550 catalyst is the best, and the NO conversion rate reaches more than 80% at 300–500°C.

[0030] Example 3 Effect of different supports on the performance of 0.2CuSO4-0.4MnSO4 / Y catalyst

[0031] The CuSO4-MnSO4 / Y catalysts with different supports were prepared by co-impregnation method. First, CuSO4·5H2O and MnSO4·H2O were mixed at a certain molar ratio (n Cu :n Mn =1:2, and control the Cu content in the solution 2+ With Mn 2+ γ-Al2O3 (total concentration of 0.6 mmol / g) was dissolved in deionized water. Different carriers Y (γ-Al2O3, TiO2, SiO2) were added to the mixed solution and magnetically stirred for 1 hour. The solvent was then evaporated in an oil bath at 110°C and dried in an oven at 110°C for 3 hours. After drying, the solid sample was ground and placed in a crucible and calcined in a muffle furnace at 550°C for 3 hours (heating rate of 2°C / min). The final product was cooled and ground to obtain a CuSO4-MnSO4 / Y catalyst. The catalyst was labeled 0.2CuSO4-0.4MnSO4 / Y (Y = γ-Al2O3, TiO2, SiO2).

[0032] Depend on Figure 3It can be seen that when SiO2 is used as the carrier, the overall activity of the 0.2CuSO4-0.4MnSO4 / SiO2 catalyst is the worst; when TiO2 is used as the carrier, the low-temperature (250-300℃) activity of the 0.2CuSO4-0.4MnSO4 / TiO2 catalyst is slightly better than that of the 0.2CuSO4-0.4MnSO4 / Al2O3 catalyst, but the overall activity of the 0.2CuSO4-0.4MnSO4 / Al2O3 catalyst is better than that of other carriers.

[0033] Example 4: Sulfur and water resistance of 0.2CuSO4-0.4MnSO4 / Al2O3-550 catalyst

[0034] Depend on Figure 4 It can be seen that the 0.2CuSO4-0.4MnSO4 / Al2O3-550 catalyst has good sulfur and water resistance. After the introduction of H2O and SO2, the activity can be maintained above 90% within 15 hours.

[0035] It can be seen from the above examples that the 0.2CuSO4-0.4MnSO4 / Al2O3-550 catalyst prepared in the present invention not only has a wide activity window, but also has excellent sulfur and water resistance.

[0036] Example 5 X-ray diffraction (XRD) test

[0037] XRD tests were carried out on γ-Al2O3, 0.4MuSO4 / Al2O3-550, 0.6MnSO4 / Al2O3-550, 0.6CuSO4 / Al2O3-550, 0.2CuSO4 / Al2O3-550, 0.1CuSO4-0.5MnSO4 / Al2O3-550, 0.2CuSO4-0.4MnSO4 / Al2O3-550, 0.3CuSO4-0.3MnSO4 / Al2O3-550, CuSO4 and MnSO4.

[0038] Figure 5The diffraction peaks of metal sulphate appeared on 0.6CuSO4 / Al2O3-550, 0.6MnSO4 / Al2O3-550, 0.1CuSO4-0.5MnSO4 / Al2O3-550 and 0.3CuSO4-0.3MnSO4 / Al2O3-550 besides the diffraction peaks of carrier γ-Al2O3. Compared with 0.6CuSO4 / Al2O3-550 and 0.6MnSO4 / Al2O3-550, the diffraction peaks of metal sulphate on 0.1CuSO4-0.5MnSO4 / Al2O3-550 and 0.3CuSO4-0.3MnSO4 / Al2O3-550 showed different degrees of reduction. In addition, no diffraction peaks of metal sulphate were observed in 0.2CuSO4-0.4MnSO4 / Al2O3-550. The XRD results showed that the synergistic effect between Cu and Mn promoted the dispersion behavior of metal sulphate on the carrier, and this synergistic effect changed with the change of Cu / Mn ratio. When Cu / Mn = 1:2, the synergistic effect of Cu and Mn in the catalyst was the most significant, which made the metal sulphate on the surface of Al2O3 carrier present a highly dispersed state, and the active sites were exposed to the greatest extent, which was conducive to the adsorption and activation of reactant molecules, thereby improving the catalytic activity of the catalyst.

[0039] While the embodiments of the application have been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the application. Therefore, the scope of the application is defined not by the detailed description of the embodiments but by the appended claims and their equivalents.

Claims

1. A method for preparing a metal sulfate modified supported aluminum-based denitration catalyst, characterized in that: The following steps are involved: (1) Dissolve copper salt and manganese salt in deionized water at a certain molar ratio, add γ-Al2O3 to the mixed solution and stir magnetically; (2) Evaporate the solvent in an oil bath and dry in an oven; (3) After drying, the solid sample was ground and placed in a crucible, and calcined in a muffle furnace. The final product was cooled and ground to obtain a CuSO4-MnSO4 / Al2O3 catalyst. The catalyst was labeled as xCuSO4-yMnSO4 / Al2O3, where x and y represent the loading amounts of CuSO4 and MnSO4, respectively, in mmol / gγ-Al2O3, and x+y=0.

6.

2. The method for preparing the metal sulfate-modified supported aluminum-based denitration catalyst according to claim 1, wherein: In the step (1), the Cu 2+ With Mn 2+ The total concentration is 0.6 mmol / gγ-Al2O3; the copper salt includes CuSO4·5H2O, CuSO4·2H2O or CuSO4; the manganese salt includes MnSO4·4H2O, MnSO4·H2O or MnSO4.

3. The method for preparing the metal sulfate-modified supported aluminum-based denitration catalyst according to claim 2, wherein: In the step (1), the magnetic stirring time is 1 h.

4. The method for preparing the metal sulfate-modified supported aluminum-based denitration catalyst according to claim 3, wherein: In the step (2), the solvent is evaporated in an oil bath at 110°C.

5. The method for preparing the metal sulfate modified supported aluminum-based denitration catalyst according to claim 4, characterized in that: In the step (2), the product is dried in an oven at 110° C. for 3 hours.

6. The method for preparing the metal sulfate-modified supported aluminum-based denitration catalyst according to claim 5, wherein: In the step (3), the calcination temperature is 550°C.

7. The method for preparing the metal sulfate-modified supported aluminum-based denitration catalyst according to claim 6, wherein: In the step (3), the roasting time is 3 hours.

8. The method for preparing the metal sulfate-modified supported aluminum-based denitration catalyst according to claim 7, wherein: In the step (3), the heating rate is 2°C / min.

9. A metal sulfate-modified supported aluminum-based denitration catalyst prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the metal sulfate modified supported aluminum-based denitration catalyst according to claim 9 in catalytic denitration.

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