Preparation method and application of manganese-based catalyst for resisting ammonium bisulfate poisoning in low-temperature and high-humidity flue gas
By combining tannin acid with γ-Al2O3 and methacryloyloxypropyltrimethoxysilane, Mn-Sib/γ-Al2O3 (TAa) catalyst was prepared, which solved the problem that existing catalysts were easily poisoned and had poor stability in low-temperature and high-humidity flue gas environment, and achieved the effect of efficient removal of VOCs and anti-ammonium bisulfate poisoning.
Patent Information
- Application Number
- CN202510187342.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-20
- Publication Date
- 2025-06-27
AI Technical Summary
Existing catalysts are prone to poisoning in low-temperature and high-humidity flue gas environments, with poor stability and reduced efficiency, especially the presence of ammonium bisulfate leads to the deactivation of the catalyst.
The Mn-Sib/γ-Al2O3 (TAa) catalyst was prepared by combining tannin acid with γ-Al2O3 and methacryloyloxypropyltrimethoxysilane. The acidic sites and metal dispersion of the catalyst were regulated through the surface adhesion characteristics of tannin acid and the chelation of negatively charged polyphenol groups, and the anti-toxicity performance was improved.
Under the harsh conditions of low temperature, high humidity, high water and sulfur, the catalyst's removal efficiency of VOCs is only reduced by 3%, maintaining a high efficiency of 90% for a long time, which is far better than existing catalysts, and is low in cost, with good renewability and environmental friendliness.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of catalysts, and in particular relates to a preparation method and application of a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas. Background Art
[0002] Catalysis is an effective means to control various gaseous pollutants in coal-fired industrial flue gas, such as NO, Hg, and VOCs. However, in order to reach the effective temperature window of existing commercial catalysts (mainly vanadium-based catalysts), it is necessary to reheat the flue gas, resulting in a large energy consumption in the pollutant control process. Therefore, it is of great significance to develop new catalysts with high activity under low-temperature flue gas conditions and reduce the energy consumption of pollutant control.
[0003] MnO x can achieve good catalytic activity at low temperatures, but the main problems restricting its application are that: MnO x is very easy to be poisoned, resulting in low stability and lifespan. The components that poison MnO x come from sulfur dioxide, escaped ammonia, and a large amount of water vapor in low-temperature flue gas. In particular, ammonia and sulfur dioxide are prone to form ammonium bisulfate (ABS) crystals under low-temperature conditions. ABS is easy to adhere to the catalyst surface, resulting in the inactivation of the MnO x catalyst. The presence of water vapor in the flue gas and in high-humidity flue gas makes the process of catalyst poisoning by ABS more serious. Some studies have tested the influence of flue gas components on Mn catalysts. After introducing 200 ppm SO2, the activity of the Mn catalyst decreased from 93% to 78%. After adding 10 vol% H2O, the activity of the manganese-based catalyst further decreased to 50%. In the experimental group of CeO2-V2O5 / TiO2 catalysts prepared by some researchers, after introducing SO2, the NO x conversion rate did not decrease, but after introducing SO2 and H2O simultaneously, the NO x conversion rate decreased by 36%.
[0004] In current research, methods to improve the anti-poisoning performance of catalysts generally include structural modification, metal doping, promoting the dispersion of active sites, and surface modification, etc. For example, hierarchical structures including core-shell, multi-shell, and mesoporous zeolites can prevent toxic gases from directly contacting catalytically active substances, but the construction of fine structures poses challenges to large-scale production. Some foreign doped metals, such as Ce and Fe, protect active components from SO2 poisoning by preferentially adsorbing SO2, but it is reported that they will promote the generation of unwanted SO3. Sulfonated modified catalysts and siloxane modified catalysts show anti-poisoning performance by reducing the adsorption of SO2 and H2O respectively, but lead to a decrease in catalyst efficiency. The limitations of the above strategies make it very urgent to develop new anti-poisoning catalysts. Summary of the Invention
[0005] The object of the present invention is to overcome the deficiencies of the prior art and provide a preparation method and application of a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas, so as to solve the problems of easy poisoning, poor stability and reduced efficiency of existing catalysts in a low-temperature and high-humidity flue gas environment.
[0006] The present invention solves its technical problems by adopting the following technical solutions:
[0007] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas, comprising the following steps:
[0008] S1. Mix tannic acid with γ-Al2O3 and dissolve them in deionized water, add an initiator, stir, and dry to obtain γ-Al2O3(TA a );
[0009] S2. Mix methacryloxypropyltrimethoxysilane with absolute ethanol, stir, add γ-Al2O3(TA a ), let it stand, pour off the excess supernatant, and cure to obtain Si b / γ-Al2O3(TA a );
[0010] S3. Mix the manganese salt solution with Si b / γ-Al2O3(TA a ), stir well and impregnate. After the impregnation is completed, heat to evaporate the liquid, place it in a muffle furnace, and calcine to obtain the Mn-Si b / γ-Al2O3(TA a ) catalyst;
[0011] Moreover, TA is tannic acid, the value of a is 1-15, and the value of b is 0.03-0.6.
[0012] Moreover, in step S1, the initiator is ammonia water.
[0013] Moreover, in step S1, the stirring time is 10-15h, the drying temperature is 60-100°C, and the drying time is 10-15h.
[0014] Moreover, in step S2, the stirring time is 20-40min, and the standing time is 4-8min.
[0015] Moreover, in step S2, the specific steps of the curing are: first cure at room temperature for 1h, then put it into an oven and cure at 40°C for 1h, and then raise the temperature to 100°C and cure for 1h.
[0016] Moreover, the mass ratio of tannic acid: γ-Al2O3: methacryloxypropyltrimethoxysilane: manganese atoms is 1-15:100:0.03-0.6:1-30.
[0017] Moreover, in step S3, stir and impregnate for 10-15 h.
[0018] Moreover, in step S4, the calcination temperature of the muffle furnace is 400-800 °C, and the calcination time is 200-400 min.
[0019] A manganese-based catalyst for resisting ammonium bisulfate poisoning in low-temperature and high-humidity flue gas, with a structure of Mn-Si b / γ-Al2O3(TA a ), where TA is tannic acid, the value of a is 1-15, the value of b is 0.03-0.6, or the mass ratio of tannic acid: γ-Al2O3: methacryloxypropyltrimethoxysilane: manganese atoms is 1-15:100:0.03-0.6:1-30.
[0020] Application of a manganese-based catalyst for resisting ammonium bisulfate poisoning in low-temperature and high-humidity flue gas in catalytic removal of VOCs and resisting ammonium bisulfate poisoning in low-temperature and high-humidity flue gas.
[0021] The advantages and positive effects of the present invention are:
[0022] 1. The surface attachment characteristics of tannic acid molecules in the present invention make the carrier surface have abundant -OH functional groups, which can be used for bonding siloxane. Since siloxane is difficult to form hydrogen bonds with water, the surface of the catalyst is given hydrophobicity, thereby effectively reducing the adsorption of H2O.
[0023] 2. The negatively charged polyphenol groups on tannic acid in the present invention can chelate positively charged metal ions. At the same time, the steric hindrance effect brought by the branched structure of tannic acid helps to promote the dispersion of MnO x . The improvement of metal dispersion helps to improve the anti-poisoning performance of the catalyst.
[0024] 3. Tannic acid in the present invention can regulate the acidic sites on the catalyst, thereby adjusting the adsorption behaviors of SO2 and NH3. By weakening the adsorption of SO2 and strengthening the adsorption of NH3 at the same time, SO2 and NH3 are separated, so it is difficult to form ABS.
[0025] 4. The catalyst prepared by the present invention has good removal effect on VOCs under harsh conditions of low temperature and high water-sulfur content (150 °C, 1000 ppm SO2, 500 ppm NH3, 15 vol.% H2O). The efficiency reduction is only controlled at about 3%, and it maintains a high efficiency of 90% for a long time, far superior to existing catalysts.
[0026] 5. In the present invention, tannic acid is derived from natural plants, with low cost, good renewability and environmental friendliness; inorganic siloxane has excellent thermal stability and low cost; the preparation method of the catalyst is simple and has wide feasibility in industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is the chemical structural formula diagram of tannic acid of the present invention.
[0028] Figure 2 It is the XRD diagram of the Mn-Si b / γ(TA a ) catalyst of the present invention.
[0029] Figure 3 It is the removal efficiency diagram of o-xylene by the Mn-Si 0.09 / γ(TA5) catalyst in Example 3 of the present invention.
[0030] Figure 4 It is the removal efficiency diagram of VOCs at different tannic acid contents of the present invention.
[0031] Figure 5 It is the removal efficiency diagram of VOCs at different inorganic siloxane contents of the present invention.
[0032] Figure 6 It is the removal efficiency diagram of VOCs by the catalysts Mn-Si / γ, Mn-Si / γ(TA5), Mn-Si / γ(TA 15 ) of the present invention at different temperatures.
[0033] Figure 7 It is the removal rate diagram of o-xylene by the manganese-based catalyst under different flue gas conditions of the present invention.
[0034] Figure 8 It is the resistance diagram of the manganese-based catalyst of the present invention to H2O.
[0035] Figure 9 It is the resistance diagram of the manganese-based catalyst of the present invention to SO2.
[0036] Figure 10 It is the resistance diagram of the manganese-based catalyst of the present invention to H2O+SO2.
[0037] Figure 11 It is the resistance diagram of the manganese-based catalyst of the present invention to SO2+NH3.
[0038] Figure 12 It is the resistance diagram of the manganese-based catalyst of the present invention to H2O+SO2+NH3. DETAILED DESCRIPTION OF THE INVENTION
[0039] The present invention will be further described in detail below through specific embodiments. The following embodiments are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.
[0040] A preparation method of a manganese-based catalyst for resisting ammonium bisulfate poisoning in low-temperature and high-humidity flue gas comprises the following steps:
[0041] S1. Mix tannic acid and γ-Al2O3 and dissolve them in deionized water, add an initiator, stir, and dry to obtain γ-Al2O3(TA a );
[0042] S2. Mix methacryloxypropyltrimethoxysilane and absolute ethanol, stir, add γ-Al2O3(TA a ), let it stand, pour off the excess supernatant, and cure to obtain Si b / γ-Al2O3(TA a );
[0043] S3. Mix a manganese salt solution with Si b / γ-Al2O3(TA a ), stir well and impregnate. After the impregnation is completed, heat to evaporate the liquid, place it in a muffle furnace, and calcine to obtain a Mn-Si b / γ-Al2O3(TA a ) catalyst;
[0044] Wherein, TA is tannic acid, the value of a is 1-15, and the value of b is 0.03-0.6.
[0045] Wherein, as Figure 2 shown, Mn exists in the forms of Mn2O3, Mn3O4 and MnO2. The characteristic diffraction peaks appearing at 37.0°, 45.8° and 66.8° indicate the existence of γ-Al2O3; the characteristic peak at 32.3° indicates the existence of Mn3O4; the characteristic peak at 42.5° indicates the existence of MnO2.
[0046] As shown in Table 1, it is effectively confirmed that the manganese-based catalyst in the present invention can effectively resist ammonium bisulfate poisoning in low-temperature and high-humidity flue gas. The efficiency decline is caused by the introduction of water, sulfur and ammonia in the flue gas to form ammonium bisulfate. The efficiency decline range of the catalyst prepared in the present invention is smaller, which proves its anti-poisoning performance.
[0047] Table 1 Comparison of anti-poisoning performance between the manganese-based catalyst prepared in the present invention and the existing catalyst
[0048]
[0049] Catalysis of VOCs:
[0050] The catalyst sample was placed in a reactor, and 40 ppm of o-xylene, 5 vol.% O2, and carrier gas N2 were introduced under the conditions of a reaction temperature of 250 °C and a space velocity of 60,000 / h. The outlet concentration of o-xylene was monitored under the conditions of introducing 0 vol.% H2O and 10 vol.% H2O, 1000 ppm SO2 flue gas, respectively, and its removal efficiency was calculated.
[0051] Note: Catalytic efficiency for VOs:
[0052]
[0053] η represents the catalytic oxidation efficiency, C (in) is the concentration (ppm) of the pollutant entering the reactor, C (out) is the concentration of the pollutant at the reactor outlet (ppm).
[0054] For ease of understanding and discussion, Mn-Si in the present invention b / γ-Al2O3 (TA a ) is partially abbreviated as Mn-Si b / γ (TA a ).
[0055] Example 1
[0056] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning for low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst when the mass of tannic acid is 1 g, including the following steps:
[0057] S1. Dissolve 1 g of tannic acid and 100 g of γ-Al2O3 in 15 mL of deionized water, add 5 mL of ammonia water, stir magnetically for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3 (TA1);
[0058] S2. Dissolve 0.09 g of methacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol, slowly add 1 g of γ-Al2O3 (TA1) powder under the condition of magnetic stirring for 30 min, pour off the excess supernatant after standing for 5 min, cure at room temperature for 1 hour, and then put it into an oven and cure at 40 °C and 100 °C for 1 hour respectively. After the curing of the coating is completed, Si 0.09 / γ-Al2O3 (TA1) is obtained;
[0059] S3. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add 1 g of Si 0.09 / γ-Al2O3 (TA1), stir magnetically for impregnation for 12 h; after the impregnation is completed, heat to evaporate the liquid, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain Mn-Si 0.09 / γ-Al2O3 (TA1) catalyst.
[0060] Catalysis of VOCs:
[0061] Put Mn-Si 0.09 / γ-Al2O3 (TA1) catalyst sample into the reactor. Under the conditions of reaction temperature 250 °C and space velocity 60,000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2 and carrier gas N2. The calculated catalytic efficiency for o-xylene is 78.39%.
[0062] Example 2
[0063] A preparation method of a manganese-based catalyst for resisting ammonium bisulfate poisoning in low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst when the mass of tannic acid is 3 g, including the following steps:
[0064] S1. Dissolve 3 g of tannic acid and 100 g of γ-Al2O3 in 15 mL of deionized water, add 5 mL of ammonia water, stir magnetically for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3 (TA3);
[0065] S2. Dissolve 0.09 g of methacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol, slowly add 1 g of γ-Al2O3 (TA3) powder under the condition of magnetic stirring for 30 min, let it stand for 5 min, then pour off the excess supernatant, cure at room temperature for 1 hour, and then put it into the oven and cure at 40 °C and 100 °C for 1 hour respectively. After the coating is cured, obtain Si 0.09 / γ-Al2O3 (TA3);
[0066] S3. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add 1 g of Si 0.09 / γ-Al2O3 (TA3), stir magnetically for impregnation for 12 h; after impregnation, heat to evaporate the liquid, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain Mn-Si 0.09 / γ-Al2O3 (TA3) catalyst.
[0067] Catalysis of VOCs:
[0068] Put Mn-Si 0.09 / γ-Al2O3 (TA3) catalyst sample into the reactor. Under the conditions of reaction temperature 250 °C and space velocity 60,000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2 and carrier gas N2. The calculated catalytic efficiency for o-xylene is 84.59%.
[0069] Example 3
[0070] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst when the mass of tannic acid is 5 g, including the following steps:
[0071] S1. Dissolve 5 g of tannic acid and 100 g of γ-Al2O3 in 15 mL of deionized water, add 5 mL of ammonia water, stir magnetically for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3(TA5);
[0072] S2. Dissolve 0.09 g of methacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol, slowly add 1 g of γ-Al2O3(TA5) powder under the condition of magnetic stirring for 30 min, let it stand for 5 min, then pour off the excess supernatant, cure at room temperature for 1 h, and then put it into an oven and cure at 40 °C and 100 °C for 1 h respectively. After the curing of the coating is completed, obtain Si 0.09 / γ-Al2O3(TA5);
[0073] S3. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add Si 0.09 / γ-Al2O3(TA5) 1 g, stir magnetically for impregnation for 12 h; after the impregnation is completed, heat to evaporate the liquid, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain the Mn-Si 0.09 / γ-Al2O3(TA5) catalyst.
[0074] Catalysis of VOCs:
[0075] Place the Mn-Si 0.09 / γ-Al2O3(TA5) catalyst sample in a reactor, and at a reaction temperature of 250 °C and a space velocity of 60000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2 and the carrier gas N2, and calculate that the catalytic efficiency for o-xylene is 93.64%.
[0076] From Figure 3 it can be seen that with the introduction of the interfering gas, the catalyst efficiency decreased by 3.8%, and there was no further decrease in the subsequent 30-hour test, which proves the excellent stability of the Mn-Si 0.09 / γ-Al2O3(TA5) in complex flue gas.
[0077] Example 4
[0078] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst when the mass of tannic acid is 8 g, including the following steps:
[0079] S1. Dissolve 8 g of tannic acid and 100 g of γ-Al2O3 in 15 mL of deionized water, add 5 mL of ammonia water, stir magnetically for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3(TA8).
[0080] S2. Dissolve 0.09 g of methacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol, slowly add 1 g of γ-Al2O3(TA8) powder under magnetic stirring for 30 min, let it stand for 5 min, then pour off the excess supernatant, cure at room temperature for 1 h, and then put it into an oven and cure at 40 °C and 100 °C for 1 h respectively. After the coating is cured, Si 0.09 / γ-Al2O3(TA8) is obtained.
[0081] S3. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add 1 g of Si 0.09 / γ-Al2O3(TA8), stir magnetically and impregnate for 12 h; after impregnation, heat to evaporate the liquid, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain the Mn-Si 0.09 / γ-Al2O3(TA8) catalyst.
[0082] Catalysis of VOCs:
[0083] Place the Mn-Si 0.09 / γ-Al2O3(TA8) catalyst sample in a reactor, and at a reaction temperature of 250 °C and a space velocity of 60000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2 and the carrier gas N2, and calculate that the catalytic efficiency for o-xylene is 90.38%.
[0084] Example 5
[0085] A preparation method of a manganese-based catalyst for resisting ammonium bisulfate poisoning in low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst with 15 g of tannic acid, including the following steps:
[0086] S1. Dissolve 15 g of tannic acid and 100 g of γ-Al2O3 in 15 mL of deionized water, add 5 mL of ammonia water, stir magnetically for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3(TA 15 ).
[0087] S2. Dissolve 0.09 g of methacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol, slowly add 1 g of γ-Al2O3(TA 15) The powder was allowed to stand for 5 min, and then the excess supernatant was poured off. It was cured at room temperature for 1 hour and then placed in an oven and cured at 40 °C and 100 °C for 1 hour respectively. After the coating was cured, Si 0.09 / γ-Al2O3(TA 15 ) was obtained;
[0088] S3. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water. Then add 1 g of Si 0.09 / γ-Al2O3(TA 15 ). Stir magnetically for 12 h. After impregnation, heat to evaporate the liquid and place it in a muffle furnace. Calcinate it at 500 °C for 300 min to obtain the Mn-Si 0.09 / γ-Al2O3(TA 15 ) catalyst.
[0089] Catalysis of VOCs:
[0090] Place the Mn-Si 0.09 / γ-Al2O3(TA 15 ) catalyst sample in the reactor. At a reaction temperature of 250 °C and a space velocity of 60000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2 and the carrier gas N2. The catalytic efficiency for o-xylene is calculated to be 86.58%.
[0091] According to Examples 1-5, it can be seen that Figure 4 when the mass ratio of tannic acid to alumina support is 5%, the removal rate of o-xylene by the manganese-based catalyst is the highest.
[0092] Example 6
[0093] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst when the mass of methacryloxypropyltrimethoxysilane is 0.03 g, including the following steps:
[0094] S1. Dissolve 5 g of tannic acid and 100 g of γ-Al2O3 in 15 mL of deionized water, add 5 mL of ammonia water, stir magnetically for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3(TA5);
[0095] S2. Dissolve 0.03 g of methacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol. Slowly add 1 g of γ-Al2O3(TA5) powder under the condition of magnetic stirring for 30 min. Let it stand for 5 min and then pour off the excess supernatant. Cure it at room temperature for 1 hour, then place it in an oven and cure it at 40 °C and 100 °C for 1 hour respectively. After the coating is cured, Si 0.03 / γ-Al2O3(TA5);
[0096] S3. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add Si 0.03 / γ-Al2O3(TA5) 1 g, and magnetically stir for impregnation for 12 h; after the impregnation is completed, heat to evaporate the liquid to dryness, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain the Mn-Si 0.03 / γ-Al2O3(TA5) catalyst.
[0097] Catalysis of VOCs:
[0098] Place the Mn-Si 0.03 / γ-Al2O3(TA5) catalyst sample in a reactor, and under the conditions of a reaction temperature of 250 °C and a space velocity of 60000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2, and the carrier gas N2, and calculate that the catalytic efficiency for o-xylene is 72.7%.
[0099] Example 7
[0100] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning for low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst when the mass of methacryloxypropyltrimethoxysilane is 0.06 g, including the following steps:
[0101] S1. Dissolve 5 g of tannic acid and 100 g of γ-Al2O3 in 15 mL of deionized water, add 5 mL of ammonia water, magnetically stir for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3(TA5);
[0102] S2. Dissolve 0.06 g of methacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol, slowly add 1 g of γ-Al2O3(TA5) powder under the condition of magnetic stirring for 30 min, let it stand for 5 min, then pour off the excess supernatant, cure at room temperature for 1 hour, and then put it in an oven and cure at 40 °C and 100 °C for 1 hour respectively. After the curing of the coating is completed, obtain Si 0.06 / γ-Al2O3(TA5);
[0103] S3. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add Si 0.06 / γ-Al2O3(TA5) 1 g, and magnetically stir for impregnation for 12 h; after the impregnation is completed, heat to evaporate the liquid to dryness, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain the Mn-Si 0.06 / γ-Al2O3(TA5) catalyst.
[0104] Catalysis of VOCs:
[0105] Put Mn-Si 0.06 / γ-Al2O3 (TA5) catalyst sample into the reactor. Under the conditions of reaction temperature 250 °C and space velocity 60,000 / h, introduce 50 ppm o-xylene, 5 vol.% O2 and carrier gas N2, and the catalytic efficiency for o-xylene is calculated to be 80.42%.
[0106] Example 8
[0107] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning for low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst when the mass of methacryloxypropyltrimethoxysilane is 0.3 g, including the following steps:
[0108] S1. Dissolve 5 g of tannic acid and 100 g of γ-Al2O3 in 15 mL of deionized water, add 5 mL of ammonia water, stir magnetically for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3 (TA5);
[0109] S2. Dissolve 0.3 g of methacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol, slowly add 1 g of γ-Al2O3 (TA5) powder under the condition of magnetic stirring for 30 min, pour off the excess supernatant after standing for 5 min, cure at room temperature for 1 hour, then put it into the oven and cure at 40 °C and 100 °C for 1 hour respectively. After the curing of the coating is completed, obtain Si 0.3 / γ-Al2O3 (TA5);
[0110] S3. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add Si 0.3 / γ-Al2O3 (TA5) 1 g, stir magnetically for impregnation for 12 h; after the impregnation is completed, heat to evaporate the liquid, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain Mn-Si 0.3 / γ-Al2O3 (TA5) catalyst.
[0111] Catalysis of VOCs:
[0112] Put Mn-Si 0.3 / γ-Al2O3 (TA5) catalyst sample into the reactor. Under the conditions of reaction temperature 250 °C and space velocity 60,000 / h, introduce 50 ppm o-xylene, 5 vol.% O2 and carrier gas N2, and the catalytic efficiency for o-xylene is calculated to be 81.99%.
[0113] Example 9
[0114] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning for low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst when the mass of methacryloxypropyltrimethoxysilane is 0.6 g, including the following steps:
[0115] S1. Dissolve 5 g of tannic acid and 100 g of γ-Al2O3 in 15 mL of deionized water, add 5 mL of ammonia water, stir magnetically for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3(TA5);
[0116] S2. Dissolve 0.6 g of methacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol, slowly add 1 g of γ-Al2O3(TA5) powder under the condition of magnetic stirring for 30 min, pour off the excess supernatant after standing for 5 min, cure at room temperature for 1 hour, and then put it into an oven and cure at 40 °C and 100 °C for 1 hour respectively. After the coating is cured, obtain Si 0.6 / γ-Al2O3(TA5);
[0117] S3. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add Si 0.6 / γ-Al2O3(TA5) 1 g, stir magnetically for impregnation for 12 h; after impregnation, heat to evaporate the liquid, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain Mn-Si 0.6 / γ-Al2O3(TA5) catalyst.
[0118] Catalysis of VOCs:
[0119] Place the Mn-Si 0.6 / γ-Al2O3(TA5) catalyst sample in a reactor, and under the conditions of a reaction temperature of 250 °C and a space velocity of 60000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2 and carrier gas N2, and calculate that the catalytic efficiency for o-xylene is 75.36%.
[0120] According to Example 3 and Examples 6-9, it can be seen that when the mass ratio of tannic acid to the alumina support is 5%, and the mass of methacryloxypropyltrimethoxysilane and the alumina support is 0.09 g, the o-xylene removal rate of the manganese-based catalyst is the highest. Therefore, the Mn-Si Figure 5 / γ-Al2O3(TA5) catalyst in Example 3 has the most excellent performance. 0.09 / γ-Al2O3(TA5) catalyst has the most excellent performance.
[0121] Comparative Example 1
[0122] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning for low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst without tannic acid modification, including the following steps:
[0123] S1. Dissolve 0.09 g of methylacryloxypropyltrimethoxysilane in 5.91 mL of absolute ethanol. Slowly add 1 g of γ-Al2O3 powder under magnetic stirring for 30 min. After standing for 5 min, pour off the excess supernatant, cure at room temperature for 1 h, then put it into an oven and cure at 40 °C and 100 °C for 1 h respectively. After the curing of the coating is completed, Si 0.09 / γ-Al2O3 is obtained;
[0124] S2. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add 1 g of Si 0.09 / γ-Al2O3. Stir magnetically for impregnation for 12 h; after the impregnation is completed, heat to evaporate the liquid, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain the Mn-Si 0.09 / γ-Al2O3 catalyst.
[0125] Catalysis of VOCs:
[0126] Place the Mn-Si 0.09 / γ-Al2O3 catalyst sample in a reactor. At a reaction temperature of 250 °C and a space velocity of 60000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2 and the carrier gas N2. It is measured that the Mn-Si 0.09 / γ-Al2O3, Mn-Si 0.09 / γ-Al2O3(TA5), Mn-Si 0.09 / γ-Al2O3(TA 15 (simplify the siloxane content of 0.09) The removal efficiencies of VOCs at different temperatures are respectively Figure 6 as shown.
[0127] Comparative Example 2
[0128] A preparation method of a manganese-based catalyst resistant to ammonium bisulfate poisoning for low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst without tannic acid and methylacryloxypropyltrimethoxysilane modification, including the following steps:
[0129] S1. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add 1 g of activated alumina support and stir magnetically for impregnation for 12 h;
[0130] S2. After impregnation, heat to evaporate the liquid to dryness, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain the Mn / γ-Al2O3 catalyst.
[0131] Catalysis of VOCs:
[0132] Place the Mn / γ-Al2O3 catalyst sample in a reactor. Under the conditions of a reaction temperature of 250 °C and a space velocity of 60,000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2, and the carrier gas N2. The catalytic efficiency for o-xylene is calculated to be 65%.
[0133] Comparative Example 3
[0134] A preparation method of a manganese-based catalyst for resisting ammonium bisulfate poisoning in low-temperature and high-humidity flue gas. This example provides a preparation method of a manganese-based catalyst without modification by methacryloxypropyltrimethoxysilane, including the following steps:
[0135] S1. Dissolve tannic acid and γ-Al2O3 in a mass ratio of 5:100 in 15 mL of deionized water, add 5 mL of ammonia water, stir magnetically for 12 h, and dry at 80 °C for 12 h to obtain γ-Al2O3(TA5).
[0136] S2. Weigh 0.24 g of MnCl2·4H2O and dissolve it in 20 mL of deionized water, then add 1 g of γ-Al2O3(TA5), and stir magnetically for impregnation for 12 h; after impregnation, heat to evaporate the liquid to dryness, place it in a muffle furnace, and calcine at 500 °C for 300 min to obtain the Mn / γ-Al2O3(TA5) catalyst.
[0137] Catalysis of VOCs:
[0138] Place the Mn / γ-Al2O3(TA5) catalyst sample in a reactor. Under the conditions of a reaction temperature of 250 °C and a space velocity of 60,000 / h, introduce 50 ppm of o-xylene, 5 vol.% O2, and the carrier gas N2. The catalytic efficiency for o-xylene is calculated to be 55%.
[0139] It can be seen from Figure 7 that the introduction of water vapor, SO2, and NH3 alone or in coexistence into the reaction atmosphere results in different degrees of reduction in catalytic efficiency. The coexistence of H2O, SO2, and NH3 in the feed gas causes the most serious catalyst poisoning, and the catalytic efficiency of the Mn / γ-Al2O3 catalyst in Comparative Example 2 drops sharply from 70% to 10%. Under the same conditions, the catalytic activity of Mn-Si 0.09 / γ-Al2O3(TA5) in Example 3 remains above 90%.
[0140] To better understand the contribution of silicone or / and tannic acid modification to the anti-poisoning performance of the catalyst, we calculated the "efficiency reduction ratio" of the catalyst caused by the interfering gas components. Silicone modification improved the water resistance of the catalyst ( Figure 8 ), and tannic acid modification improved the anti-SO2 poisoning performance of the catalyst ( Figure 9 ). Tannic acid and silicone modification showed a synergistic effect in promoting the catalytic oxidation of the catalyst, especially significant in the presence of multiple components ( Figures 10 - 12 ). It can be seen that tannic acid and inorganic silicone have superior anti-poisoning performance for catalyst modification.
[0141] When ammonia, sulfur dioxide and water vapor coexist in the flue gas, especially in the low-temperature flue gas below 250 °C, ABS will definitely be formed, resulting in catalyst poisoning. The anti-ABS poisoning performance of the catalyst in the present invention is reflected in: ① Compared with the control group, introducing complex components of water, sulfur and ammonia into the flue gas led to a significant decrease in the activity of the control catalyst, while the efficiency reduction of the preferred catalyst was very small (<4%). ② To further prove the superiority of the catalyst prepared in the present invention in terms of anti-ABS performance, we listed Table 1. Table 1 shows that the efficiency of the reported catalysts decreased significantly when facing the flue gas containing poisoning components; while the catalyst prepared in the present invention had a very small efficiency reduction under more severe flue gas conditions (high water sulfur ammonia, low temperature, long-term). ③ We demonstrated the stability of the catalyst prepared in the present invention through a 30-hour long-term experiment. The above aspects can prove the superiority of the catalyst in terms of anti-ABS poisoning performance.
[0142] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the content disclosed in the embodiments.
Claims
1. A method for preparing a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas, characterized in that: The steps include: S1. Mix tannic acid and γ-Al2O3 and dissolve them in deionized water, add initiator, stir, and dry to obtain γ-Al2O3 (TA a ), wherein TA is tannic acid; S2, methacryloxypropyl trimethoxysilane and anhydrous ethanol were mixed, stirred, and γ-Al2O3 (TA a ), let it stand, pour off the excess supernatant, solidify, and obtain Si b / γ-Al2O3(TA a ); S3, the manganese salt solution and Si b / γ-Al2O3(TA a ) mixed, fully stirred and impregnated, after impregnation, heated to evaporate the liquid, placed in a muffle furnace, calcined, to obtain Mn-Si b / γ-Al2O3(TA a )catalyst.
2. The method for preparing a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas according to claim 1, characterized in that: In step S1, the initiator is aqueous ammonia.
3. The method for preparing a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas according to claim 2, characterized in that: In step S1, the stirring time is 10-15 hours, the drying temperature is 60-100° C., and the drying time is 10-15 hours.
4. The method for modifying a manganese-based catalyst according to claim 3, characterized in that: In step S2, the stirring time is 20-40 min, and the standing time is 4-8 min.
5. The method for preparing a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas according to claim 4, characterized in that: In step S2, the specific steps of curing are: first curing at room temperature for 1 hour, then putting it into an oven, curing it at 40°C for 1 hour, and then heating it to 100°C and curing it for 1 hour.
6. The method for preparing a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas according to claim 5, characterized in that: The mass ratio of tannic acid:γ-Al2O3:methacryloxypropyltrimethoxysilane:manganese atom is 1-15:100:0.03-0.6:1-30.
7. The method for preparing a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas according to claim 1, characterized in that: In step S4, the calcination temperature of the muffle furnace is 400-800° C., and the calcination time is 200-400 min.
8. The method for preparing a manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas according to claim 1, characterized in that: The TA is tannic acid, the value of a is 1-15, and the value of b is 0.03-0.
6.
9. A manganese-based catalyst resistant to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas, characterized in that: The structure is Mn-Si b / γ-Al2O3(TA a ), wherein TA is tannic acid, a is 1-15, b is 0.03-0.6, or the mass ratio of tannic acid:γ-Al2O3:methacryloxypropyltrimethoxysilane:manganese atom is 1-15:100:0.03-0.6:1-30.
10. Use of the low-temperature and high-humidity flue gas resistant to ammonium bisulfate poisoning manganese-based catalyst according to claim 9 for catalytic removal of VOCs and resistance to ammonium bisulfate poisoning in low-temperature and high-humidity flue gas.