Iron-based denitration catalyst and application thereof

Abstract

This invention discloses an iron-based denitration catalyst, a supported Fe2O3 denitration catalyst prepared using KIT-6 mesoporous material as a carrier. The KIT-6 mesoporous material is prepared by the following method: a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer is dissolved in deionized water, concentrated hydrochloric acid and n-butanol are added, and the mixture is stirred at 35°C to form a transparent solution; then, tetraethyl orthosilicate is slowly added dropwise under vigorous stirring, and the mixture is stirred and hydrolyzed at 35°C for 24 h. The resulting suspension is transferred to a hydrothermal reactor and aged at 130–150°C for 24 h. The resulting precipitate is filtered, washed with deionized water and anhydrous ethanol to obtain a white solid, which is then heated in a muffle furnace at a heating rate of 1... o The KIT-6 catalyst was obtained by calcining at 550°C for 5 h in flowing air at a constant temperature (C / min). This invention achieves pore size regulation of KIT-6 by controlling the hydrothermal reaction temperature, and the catalyst prepared using it as a support exhibits excellent denitrification performance.

Description

Technical Field

[0001] This invention relates to an iron-based denitrification catalyst. Background Technology

[0002] Selective catalytic reduction of ammonia (NH3-SCR) is currently the mainstream technology for industrial flue gas denitrification, and it is also the most effective and mature technology with wide applications.

[0003] Iron is widely available, inexpensive, and non-toxic, making it a promising material for applications. Furthermore, iron oxides often exhibit excellent resistance to SO2 poisoning in SCR denitration reactions. However, due to a lack of sufficient acidic sites and redox capabilities, the low-temperature denitration performance of iron-based catalysts still requires further improvement. Besides doping and modification strategies, the construction of spatially confined environments is also considered an important way to enhance catalyst performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the deficiencies in the prior art and provide an iron-based denitrification catalyst that improves denitrification performance by adjusting the pore size of the support.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An iron-based denitration catalyst is disclosed, which is a supported Fe2O3 denitration catalyst prepared using KIT-6 mesoporous material as a support, with a Fe2O3 loading of 10%. The KIT-6 mesoporous material is prepared by the following method: 2.67 g of a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer is dissolved in 94 g of deionized water, 4.5 ml of concentrated hydrochloric acid and 2.67 g of n-butanol are added, and the mixture is stirred at 35 °C. A transparent solution was prepared; then 5.67 g of tetraethyl orthosilicate was slowly added dropwise under vigorous stirring, and the mixture was stirred and hydrolyzed at 35 °C for 24 h to obtain a hydrolyzed suspension; the obtained suspension was then transferred to a hydrothermal reactor and aged at 130–150 °C for 24 h, the obtained precipitate was filtered, and washed with deionized water and anhydrous ethanol to obtain a white solid, which was calcined at 550 °C for 5 h in flowing air under a muffle furnace heating rate of 1 °C / min to obtain KIT-6 mesoporous material.

[0007] KIT-6 possesses excellent chemical inertness, with regular arrangement of mesoporous channels and uniform pore size. This invention uses KIT-6 as a carrier and studies its preparation process, screening out the process parameter that has a significant impact on the pore size of KIT-6 mesoporous material—aging temperature. Based on this, the pore size of KIT-6 is adjusted, thereby improving the catalytic performance of the denitrification catalyst.

[0008] Furthermore, the above-mentioned iron-based denitration catalyst is prepared by the following method: KIT-6 material is mixed with Fe2(NO3)3·9H2O, and ground by solid-phase grinding until there is no particle feel. Then, it is calcined at 500℃ with a heating rate of 1℃ / min until Fe2(NO3)3·9H2O is completely converted into Fe2O3, thus obtaining the iron-based denitration catalyst.

[0009] Furthermore, the grinding time for the solid-phase grinding method is 10 minutes, and the grinding is followed by calcination at 500°C for 4 hours.

[0010] Furthermore, the hydrolyzed suspension is aged in a hydrothermal reactor at a preferred temperature of 150°C.

[0011] The present invention also provides the application of the iron-based denitrification catalyst in flue gas denitrification catalysis.

[0012] The temperature for denitrification catalysis is 300–400℃; more preferably, the temperature for denitrification catalysis is 350–400℃.

[0013] The present invention has the following advantages over the prior art:

[0014] This invention achieves pore size regulation of KIT-6 by controlling the aging temperature (hydrothermal reaction temperature), and uses it as a support to prepare a supported Fe2O3 denitrification catalyst, which exhibits excellent denitrification performance. The raw materials used in this denitrification catalyst are inexpensive and readily available, the preparation method is simple and rapid, energy consumption is low, and environmental pollution is minimal. It can be used for large-scale production and has potential application prospects in the field of NH3-SCR catalytic denitrification. Attached Figure Description

[0015] Figure 1 The small-angle XRD test results of the pore size of the KIT-6 mesoporous material prepared in Example 1 of this invention;

[0016] Figure 2 The TEM test results are for the KIT-6 mesoporous material prepared in Example 1 of this invention.

[0017] Figure 3 The results of BET testing are for the KIT-6 mesoporous material prepared in Example 1 of this invention.

[0018] Figure 4 The XRD test results are for Fe2O3 / KIT-X prepared in Example 2 of this invention.

[0019] Figure 5 The results show the activity of the Fe2O3 / KIT-X catalyst in Example 3 of this invention.

[0020] Figure 6The small-angle XRD test results of the pore size of the SBA-15 mesoporous material prepared in Comparative Example 1 of this invention;

[0021] Figure 7 The TEM test results are for the SBA-15 mesoporous material prepared in Comparative Example 1 of this invention.

[0022] Figure 8 The results of BET testing are shown for the SBA-15 mesoporous material prepared in Comparative Example 1 of this invention.

[0023] Figure 9 The XRD test results are for Fe2O3 / SBA-X prepared in Comparative Example 1 of this invention.

[0024] Figure 10 The activity results of the Fe2O3 / SBA-X catalyst prepared in Comparative Example 1 of this invention are shown.

[0025] In the figure, KIT-100, KIT-130, and KIT-150 represent KIT-6 mesoporous materials prepared at hydrothermal reaction temperatures of 100℃, 130℃, and 150℃, respectively; SBA-100, SBA-130, and SBA-150 represent SBA-15 mesoporous materials prepared at hydrothermal reaction temperatures of 100℃, 130℃, and 150℃, respectively; Fe2O3 / KIT-100, Fe2O3 / KIT -130 and Fe2O3 / KIT-150 represent supported Fe2O3 denitration catalysts prepared using KIT-100, KIT-130, and KIT-150 as supports, respectively; Fe2O3 / SBA-100, Fe2O3 / SBA-130, and Fe2O3 / SBA-150 represent supported Fe2O3 denitration catalysts prepared using SBA-100, SBA-130, and SBA-150 as supports, respectively. Detailed Implementation

[0026] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0027] Example 1

[0028] Preparation of KIT-6 mesoporous material:

[0029] Accurately weigh 2.67 g of triblock copolymer P123 (surfactant, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) and dissolve it in 94 g of deionized water. Add 4.5 ml of concentrated hydrochloric acid and 2.67 g of n-butanol, and stir in a 35°C oil bath using a heated magnetic stirrer to form a transparent solution. Then, increase the stirring speed and add 5.67 g of tetraethyl orthosilicate (TEOS) dropwise under vigorous stirring. Hydrolyze the solution in a 35°C oil bath for 24 h. Transfer the resulting suspension to a hydrothermal reactor and age it in an oven at X°C (X = 100, 130, 150) for 24 h. Filter the precipitate through a Buchner funnel, and wash repeatedly with deionized water and anhydrous ethanol to obtain a white solid. The sample was then dried overnight in an oven at 100°C. The resulting solid was then calcined at 550°C for 5 hours in flowing air at a heating rate of 1°C / min in a muffle furnace. The calcined KIT-6 was dried and stored for later use. For convenience, the sample was designated as KIT-X.

[0030] The obtained mesoporous material was tested, such as... Figure 1 As shown, with increasing hydrothermal reaction temperature, the diffraction peaks shift towards smaller angles, indicating a change in unit cell parameters; as... Figure 2 As shown, the obtained mesoporous material has a regularly arranged pore structure; as Figure 3 As shown, changing the temperature of hydrothermal treatment can control the pore size of mesoporous materials within a wide range.

[0031] Example 2

[0032] Preparation of denitration catalyst:

[0033] 0.45g of each of the three types of KIT-X prepared in Example 1 was weighed out as a carrier and placed in a mortar. Three portions of 0.126g of Fe2(NO3)3·9H2O were weighed out to achieve a Fe2O3 loading of 10%. The mixture was then thoroughly mixed with the carrier and ground using solid-phase grinding for about 10 minutes until no particles were felt. The resulting solid was calcined at 500℃ for 4 hours at a heating rate of 1℃ / min to convert Fe2(NO3)3·9H2O into Fe2O3. The sample was denoted as Fe2O3 / KIT-X (X represents the different hydrothermal reaction temperatures in Example 1).

[0034] The obtained denitrification catalyst was tested, such as... Figure 4 The XRD test results show that multiple characteristic diffraction peaks belonging to Fe2O3 were detected, indicating that Fe2O3 has been successfully loaded.

[0035] Example 3

[0036] Catalytic performance evaluation:

[0037] The NH3-SCR performance of the catalyst prepared in Example 2 was evaluated using a fixed-bed reactor within a temperature range of 250℃-400℃. The prepared catalyst powder was tableted using a BJ-15 powder tablet press and then crushed and sorted using a 20-40 mesh sieve. The catalyst particles were loaded into a quartz reaction tube for testing, with a catalyst dosage of 0.1 g. First, the fixed-bed reactor was heated from room temperature to 150℃ at a rate of 1℃ / min and held for 30 min, while simultaneously purging with an Ar gas stream to remove surface adsorbed impurities to ensure experimental accuracy. Next, after cooling to room temperature, 500 ppm NO, 500 ppm NH3, 5 vol% O2, and a balance gas Ar (total flow rate of 100 mL / min) were introduced until adsorption reached saturation. Subsequently, SCR activity tests were conducted within a temperature range of 250℃ to 400℃, with each 50℃ temperature point stabilized for 30 min to avoid the influence of gas adsorption. The signal changes of NO and N2O were continuously collected at the exhaust gas outlet using NO and N2O sensors (Citicel). Test results show that the denitrification catalyst prepared in this invention exhibits good catalytic activity within a temperature range of 300–400℃, and the catalyst activity increases with increasing support pore size. Figure 5 As shown.

[0038] Comparative Example 1

[0039] I. Preparation of SBA-X

[0040] Accurately weigh 4g of P123 (surfactant, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) and add it to 120ml of 2mol / L HCl solution (prepared from 100ml of deionized water and 20ml of 12mol / L concentrated hydrochloric acid). Then add 30ml of deionized water and stir in a 40℃ oil bath using a heated magnetic stirrer to form a transparent solution, ensuring complete dissolution of P123. Subsequently, increase the stirring speed and slowly add 9g of tetraethyl orthosilicate (TEOS) dropwise under vigorous stirring, and continue stirring in a 40℃ oil bath for 24h. Transfer the resulting suspension to a 150ml hydrothermal reactor and age it in an oven at X℃ (X=100, 130, 150) for 24h. Filter the resulting precipitate through a Buchner funnel, and wash repeatedly with deionized water and anhydrous ethanol to obtain a white solid, which is then dried overnight in an oven at 100℃. The obtained solid was heated from room temperature to 550°C in a muffle furnace at a heating rate of 1°C / min, and then calcined in flowing air for 5 hours before being put into use. For convenience, the sample was designated as SBA-X.

[0041] Test SBA-X, such as Figure 6 As shown, with increasing hydrothermal reaction temperature, the diffraction peaks shift towards smaller angles, indicating a change in unit cell parameters; as Figure 7As shown, the obtained SBA-X mesoporous material also has a regularly arranged pore structure; such as Figure 8 As shown, changing the hydrothermal treatment temperature can control the pore size of SBA-X mesoporous material within a wide range, and is related to... Figure 3 In comparison, under the same hydrothermal temperature treatment, the pore sizes of SBA-X and KIT-X are not significantly different.

[0042] II. Preparation of Fe2O3 / SBA-X

[0043] To prepare 0.5g Fe2O3 / SBA-X, 0.45g of each of the three types of SBA-X obtained in step one were weighed out as carriers and placed in mortars. Three 0.126g portions of Fe2(NO3)3·9H2O were weighed out to achieve a Fe2O3 loading of 10%, and then thoroughly mixed with the carriers. Solid-phase grinding was then performed for approximately 10 minutes until no particles remained. The resulting solids were calcined at 500℃ for 4 hours at a heating rate of 1℃ / min to convert Fe2(NO3)3·9H2O into Fe2O3. The samples were designated Fe2O3 / SBA-X (where X represents the different hydrothermal reaction temperatures in step one). Figure 9 The XRD test results show that multiple characteristic diffraction peaks belonging to Fe2O3 were detected, indicating that Fe2O3 has been successfully loaded.

[0044] The catalytic performance of Fe2O3 / SBA-X was also tested using the method described in Example 3. Figure 10 As shown, the catalyst activity increases with the increase of the support pore size; combined with Figure 5 Using mesoporous materials obtained under the same hydrothermal temperature treatment as a carrier, the denitrification catalyst Fe2O3 / KIT-X of this invention has superior denitrification performance compared to the Fe2O3 / SBA-X denitrification catalyst. In particular, Fe2O3 / KIT-150 has a NO conversion rate of up to 67.5% at 350℃, which is much higher than that of Fe2O3 / SBA-150 (only 52.4%).

Claims

1. An iron-based denitration catalyst, characterized in that, The iron-based denitration catalyst is a supported Fe2O3 denitration catalyst prepared using KIT-6 mesoporous material as a carrier, with a Fe2O3 loading of 10%. The KIT-6 mesoporous material is prepared by the following method: 2.67 g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is dissolved in 94 g of deionized water, 4.5 ml of concentrated hydrochloric acid and 2.67 g of n-butanol are added, and the mixture is stirred at 35°C to form a transparent solution; then, 5.67 g of tetraethyl orthosilicate is slowly added dropwise under vigorous stirring, and the mixture is stirred at 35°C for 24 h to hydrolyze, obtaining a hydrolyzed suspension; the obtained suspension is then transferred to a hydrothermal reactor and aged at 150°C for 24 h. The resulting precipitate is filtered, washed with deionized water and anhydrous ethanol to obtain a white solid, which is then heated in a muffle furnace at a heating rate of 1... o Under the condition of C / min, the KIT-6 mesoporous material was obtained by calcining at 550℃ for 5 h in flowing air; the iron-based denitrification catalyst was prepared by the following method: KIT-6 material was mixed with Fe2(NO3)3·9H2O and ground by solid-phase grinding until there was no particle feel, and then calcined at 500℃ at a heating rate of 1℃ / min until Fe2(NO3)3·9H2O was completely converted into Fe2O3, thus obtaining the iron-based denitrification catalyst.

2. The iron-based denitration catalyst according to claim 1, characterized in that, The grinding time of the solid-phase grinding method is 10 minutes, and the grinding is followed by calcination at 500℃ for 4 hours.

3. The application of the iron-based denitrification catalyst according to claim 1 or 2 in the catalytic denitrification of flue gas.

4. The application according to claim 3, characterized in that, The temperature for denitrification catalysis is 300–400℃.

5. The application according to claim 4, characterized in that, The temperature for denitrification catalysis is 350–400℃.

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