Iron-based denitration catalyst and application thereof

Abstract

The invention discloses an iron-based denitration catalyst, which is a supported Fe2O3 denitration catalyst prepared by taking a KIT-6 mesoporous material as a carrier, and the KIT-6 mesoporous material is prepared by the following method: dissolving a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer in deionized water, adding concentrated hydrochloric acid and n-butyl alcohol, and stirring at 35 DEG C to form a transparent solution; then slowly dropwise adding tetraethyl orthosilicate under violent stirring, stirring and hydrolyzing for 24 hours at 35 DEG C, transferring the obtained suspension into a hydrothermal kettle, aging for 24 hours at 130-150 DEG C, filtering the obtained precipitate, washing with deionized water and absolute ethyl alcohol to obtain a white solid, and roasting for 5 hours in flowing air at 550 DEG C at the heating rate of 1 DEG C / min in a muffle furnace to obtain the product. The pore size of KIT-6 is adjusted by controlling the hydrothermal reaction temperature, and the catalyst prepared by taking KIT-6 as a carrier shows excellent denitration performance.

Description

Technical Field

[0001] The invention relates to an iron-based denitration catalyst. Background Art

[0002] Selective catalytic reduction of ammonia (NH 3 -SCR) technology is the mainstream technology for industrial flue gas denitrification at present. It is also the most effective and mature technology and is widely used.

[0003] Iron has the advantages of wide sources, low price, non-toxicity and harmlessness, and has broad application prospects. In addition, iron oxides often show excellent resistance to SO in SCR denitrification reactions. 2 Poisoning performance. However, due to the lack of sufficient acidic sites and redox capacity, the low-temperature denitrification performance of iron-based catalysts still needs further improvement. In addition to strategies such as doping modification, the construction of a spatially confined environment is also considered to be an important way to improve catalyst performance. Summary of the invention

[0004] The purpose of the present invention is to solve the defects in the prior art and provide an iron-based denitration catalyst which improves the denitration performance by adjusting the pore size of the carrier.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] An iron-based denitration catalyst, the iron-based denitration catalyst is a supported Fe prepared using KIT-6 mesoporous material as a carrier 2 O 3 Denitrification catalyst, Fe 2 O 3 The loading amount is 10%; wherein, the KIT-6 mesoporous material is prepared by the following method: 2.67g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is dissolved in 94g of deionized water, 4.5ml of concentrated hydrochloric acid and 2.67g of n-butanol are added, and stirred at 35°C to form a transparent solution; then 5.67g of tetraethyl orthosilicate is slowly added dropwise under strong stirring, and hydrolyzed at 35°C for 24h to obtain a hydrolyzed suspension; the obtained suspension is then transferred to a hydrothermal kettle and aged at 130-150°C for 24h, the obtained precipitate is filtered, and a white solid is obtained after washing with deionized water and anhydrous ethanol, and the KIT-6 mesoporous material is obtained by calcining at 550°C in flowing air for 5h at a heating rate of 1°C / min in a muffle furnace.

[0007] KIT-6 has excellent chemical inertness, and its mesoporous channels are arranged regularly and have uniform pore sizes. The present 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 the KIT-6 mesoporous material, namely the aging temperature, thereby adjusting the pore size of KIT-6 and improving the catalytic performance of the denitrification catalyst.

[0008] Furthermore, the iron-based denitration catalyst is prepared by the following method: KIT-6 material and Fe 2 (NO 3 ) 3 9H 2 O was mixed and ground by solid phase grinding until there was no particle feeling, and then calcined at 500℃ at a heating rate of 1℃ / min to Fe 2 (NO 3 ) 3 9H 2 O is completely converted to Fe 2 O 3 , and the iron-based denitration catalyst is obtained.

[0009] Furthermore, the grinding time of the solid phase grinding method is 10 minutes, and the calcination time at 500° C. after grinding is 4 hours.

[0010] Furthermore, the hydrolysis suspension is preferably aged at a temperature of 150° C. in a hydrothermal kettle.

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

[0012] The temperature of the denitration catalysis is 300-400°C; more preferably, the temperature of the denitration catalysis is 350-400°C.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] The present invention adjusts the pore size of KIT-6 by controlling the aging temperature (hydrothermal reaction temperature), and prepares the supported Fe 2 O 3 The denitration catalyst exhibits excellent denitration performance. The raw materials used in the denitration catalyst of the present invention are cheap and readily available, the preparation method is simple and fast, the energy consumption is low, the environmental pollution is small, and it can be used for large-scale production. 3 -SCR catalytic denitrification has potential application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0016] Figure 2 TEM test results of the KIT-6 mesoporous material prepared in Example 1 of the present invention;

[0017] Figure 3 This is the BET test result of the KIT-6 mesoporous material prepared in Example 1 of the present invention;

[0018] Figure 4 The Fe prepared in Example 2 of the present invention 2 O 3 / XRD test results of KIT-X;

[0019] Figure 5 is Fe in Example 3 of the present invention 2 O 3 / Activity results of KIT-X catalyst;

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

[0021] Figure 7 TEM test results of the SBA-15 mesoporous material prepared in Comparative Example 1 of the present invention;

[0022] Figure 8 This is the BET test result of the SBA-15 mesoporous material prepared in Comparative Example 1 of the present invention;

[0023] Fig. 9 The Fe prepared in Comparative Example 1 of the present invention 2 O 3 / XRD test results of SBA-X;

[0024] Fig.10 The Fe prepared in Comparative Example 1 of the present invention 2 O 3 / Activity results of SBA-X catalyst;

[0025] In the figure, KIT-100, KIT-130, and KIT-150 respectively represent KIT-6 mesoporous materials prepared at hydrothermal reaction temperatures of 100°C, 130°C, and 150°C; SBA-100, SBA-130, and SBA-150 respectively represent SBA-15 mesoporous materials prepared at hydrothermal reaction temperatures of 100°C, 130°C, and 150°C; Fe 2 O 3 / KIT-100,Fe 2 O 3 / KIT-130,Fe 2 O 3 / KIT-150 respectively represent the loaded Fe prepared with KIT-100, KIT-130 and KIT-150 as carriers. 2 O 3 Denitrification catalyst; Fe 2 O 3 / SBA-100, Fe 2 O 3 / SBA-130,Fe 2 O 3 / SBA-150 respectively represent the supported Fe prepared with SBA-100, SBA-130, and SBA-150 as carriers. 2 O 3 Denitrification catalyst. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with specific embodiments and drawings.

[0027] Example 1

[0028] Preparation of KIT-6 mesoporous material:

[0029] Accurately weigh 2.67g of triblock copolymer P123 (surfactant, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) and dissolve it in 94g of deionized water, add 4.5ml of concentrated hydrochloric acid and 2.67g of n-butanol, and stir it into a transparent solution using a heat-collecting constant temperature heating magnetic stirrer in a 35°C oil bath. Then increase the speed, slowly add 5.67g of tetraethyl orthosilicate (TEOS) under strong stirring, and stir and hydrolyze it in a 35°C oil bath for 24h. Then transfer the resulting suspension to a hydrothermal kettle and age it in an oven at X°C (X=100, 130, 150) for 24h. The resulting precipitate is filtered through a Buchner funnel, and then repeatedly washed with deionized water and anhydrous ethanol to obtain a white solid. It was then dried in an oven at 100°C overnight, and the resulting solid was calcined at 550°C in flowing air for 5 h in a muffle furnace with a heating rate of 1°C / min. The calcined KIT-6 was dried and set aside. For convenience, the sample was recorded as KIT-X.

[0030] The obtained mesoporous materials were tested, such as Figure 1 As shown in , as the hydrothermal reaction temperature increases, the diffraction peak shifts to smaller angles, indicating that the unit cell parameters change; Figure 2 As shown, the obtained mesoporous material has a regularly arranged pore structure; Figure 3 As shown, changing the temperature of the hydrothermal treatment can control the pore size of the mesoporous material in a large range.

[0031] Example 2

[0032] Preparation of denitrification catalyst:

[0033] Weigh 0.45 g of each of the three KIT-X prepared in Example 1 as carriers and place them in a mortar, and weigh three portions of 0.126 g of Fe 2 (NO 3 ) 3 9H 2 O makes Fe 2 O 3 The loading amount was 10%, and then it was fully mixed with the carrier and ground by solid phase grinding for about 10 minutes until there was no particle feeling. The obtained solid was calcined at 500℃ for 4h with a heating rate of 1℃ / min to make Fe 2 (NO 3 ) 3 9H 2 O to Fe 2 O 3 , the sample is denoted as Fe 2 O 3 / KIT-X (X is the different hydrothermal reaction temperatures in Example 1).

[0034] The obtained denitrification catalyst was tested, such as Figure 4 The XRD test results are shown, and multiple Fe 2 O 3 The characteristic diffraction peaks of Fe 2 O 3 Successfully loaded.

[0035] Example 3

[0036] Catalytic performance evaluation:

[0037] The catalyst prepared in Example 2 was subjected to NH 3 -SCR performance evaluation. The prepared catalyst powder was pressed into tablets 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°C at a rate of 1°C / min and maintained for 30 minutes. At the same time, an Ar gas flow was used to purge the surface adsorbed impurities to ensure the accuracy of the experiment. Then, after cooling to room temperature, 500 ppm NO and 500 ppm NH 3 、5vol%O 2 and balance gas Ar (total flow rate of 100 mL / min) until saturated. Subsequently, the SCR activity test was carried out in the temperature range of 250°C to 400°C, with each 50°C as a temperature point and each temperature point stabilized for 30 minutes to avoid the influence of gas adsorption. 2O sensor (Citicel) continuously collects NO and N at the exhaust outlet 2 The test results show that the denitration catalyst prepared by the present invention exhibits good catalytic activity in the temperature range of 300-400°C, and the catalyst activity increases with the increase of the carrier pore size. Figure 5 shown.

[0038] Comparative Example 1

[0039] 1. Preparation of SBA-X

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

[0041] Test SBA-X, such as Figure 6 As shown in , as the hydrothermal reaction temperature increases, its diffraction peak also shifts to a smaller angle, indicating that the unit cell parameters change; Figure 7 As shown, the obtained SBA-X mesoporous material also has a regularly arranged pore structure; Figure 8 As shown in Figure 2, changing the temperature of the hydrothermal treatment can adjust the pore size of the SBA-X mesoporous material in a large range, and Figure 3 By comparison, under the same hydrothermal temperature treatment, the pore sizes of SBA-X and KIT-X are not much different.

[0042] 2. Fe 2 O 3 Preparation of SBA-X

[0043] To prepare 0.5 g Fe 2 O 3 / SBA-X, weigh 0.45g of each of the three SBA-X prepared in step 1 as carriers, place them in a mortar, weigh three portions of 0.126g of Fe2 (NO 3 ) 3 9H 2 O makes Fe 2 O 3 The loading amount was 10%, and then it was fully mixed with the carrier and ground by solid phase grinding for about 10 minutes until there was no particle feeling. The obtained solid was calcined at 500℃ for 4h with a heating rate of 1℃ / min to make Fe 2 (NO 3 ) 3 9H 2 O to Fe 2 O 3 , the sample is denoted as Fe 2 O 3 / SBA-X (X is the different hydrothermal reaction temperatures in step 1). Fig. 9 The XRD test results are shown, and multiple Fe 2 O 3 The characteristic diffraction peaks of Fe 2 O 3 It has also been loaded successfully.

[0044] The method of Example 3 is also used to treat Fe 2 O 3 / The catalytic performance of SBA-X was tested, such as Fig.10 As shown in Figure 2, as the pore size of the support increases, the catalyst activity also increases. Figure 5 The mesoporous material obtained by the same hydrothermal temperature treatment is used as a carrier, and the denitration catalyst Fe 2 O 3 / KIT-X compared to Fe 2 O 3 / SBA-X denitration catalyst has better denitration performance, especially Fe 2 O 3 / KIT-150, the NO conversion rate is as high as 67.5% at 350℃, much higher than Fe 2 O 3 / SBA-150 (only 52.4%).

Claims

1. An iron-based denitration catalyst, characterized in that: The iron-based denitration catalyst is a loaded Fe2O3 denitration catalyst prepared by using KIT-6 mesoporous material as a carrier, and the loading amount of Fe2O3 is 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 stirred at 35°C to form a transparent solution; then 5.67 g of tetraethyl orthosilicate is slowly added dropwise under strong stirring, and stirred and hydrolyzed at 35°C for 24 h to obtain a hydrolysis suspension; the obtained suspension is then transferred to a hydrothermal kettle, aged at 130-150°C for 24 h, the obtained precipitate is filtered, and a white solid is obtained after washing with deionized water and anhydrous ethanol, and the mixture is heated in a muffle furnace at a rate of 1 o C / min, and calcined at 550° C. in flowing air for 5 h to obtain the KIT-6 mesoporous material.

2. The iron-based denitration catalyst according to claim 1, characterized in that: The iron-based denitration catalyst is prepared by the following method: KIT-6 material is mixed with Fe2(NO3)3·9H2O, ground by solid phase grinding method until there is no particle feeling, and then calcined at 500°C at a heating rate of 1°C / min until Fe2(NO3)3·9H2O is completely converted into Fe2O3, thereby obtaining the iron-based denitration catalyst.

3. The iron-based denitration catalyst according to claim 2, characterized in that: The grinding time of the solid phase grinding method is 10 minutes, and the calcination time at 500° C. after grinding is 4 hours.

4. The iron-based denitration catalyst according to claim 3, characterized in that: The hydrolysis suspension is placed in a hydrothermal kettle at an aging temperature of 150°C.

5. Use of the iron-based denitration catalyst according to any one of claims 1 to 4 in catalyzing flue gas denitration.

6. The use according to claim 5, characterized in that: The temperature of denitrification catalysis is 300-400°C.

7. The use according to claim 6, characterized in that: The temperature of denitrification catalysis is 350-400°C.

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