A high-temperature SCR flue gas denitration catalyst for gas turbines and its preparation method

Abstract

The present invention discloses a high-temperature SCR flue gas denitration catalyst for gas turbines and a preparation method thereof. The catalyst comprises a carrier of silicon-containing tailings, active components and additives. The silicon-containing tailings contain SiO2, K2O, CaO, MgO, Al2O3 and Fe2O3, wherein SiO2 forms a SiO2-Al2O3-Fe2O3 mixed carrier with Al2O3 and Fe2O3. The preparation method is as follows: the silicon-containing tailings are pretreated to obtain silicon-containing tailings powder; the active components and additives are added to water to prepare a mixed solution, and the silicon-containing tailings powder is added thereto. After ultrasonic treatment, stirring, impregnation, drying and calcination, and then cooling, a high-temperature denitration catalyst with silicon-containing tailings as the carrier is obtained. The catalyst makes full use of each component in the silicon-containing tailings, rather than mainly using the silicon component therein, does not produce residues, greatly improves the utilization rate of the silicon-containing tailings, has high catalyst activity and a wide active temperature window.

Description

Technical Field

[0001] The present invention relates to a flue gas denitration catalyst and a preparation method thereof, and particularly relates to a high-temperature SCR flue gas denitration catalyst for a gas turbine and a preparation method thereof. Background Art

[0002] The addition of a large number of gas combined cycle units and the increasingly strict NOx emission standards will inevitably put forward higher requirements for gas turbine denitration technology. The dust and sulfur dioxide (SO 2 ) content emitted by gas turbines is relatively low, and its main pollutant is nitrogen oxides (NOx). Due to the large excess air coefficient of gas turbines, the NOx emission performance per unit power generation of gas turbines is about 1.45 times that of coal-fired power plants after ultra-low emission transformation. Under the background of increasingly strict national environmental protection requirements, the NOx emission requirements for gas turbines are becoming more and more strict. In recent years, Beijing has advocated reducing the NOx emission concentration of gas turbines to 15 mg / Nm 3 , which all put forward higher requirements for the control technology of NO x in gas turbines. Gas turbine denitration methods can be divided into two categories: one is to reduce the generation of NOx during combustion, such as water injection or steam injection during combustion, lean head end (LHE), dry low NOx combustion technology (DLN), etc.; the other is tail gas denitration technology, mainly SCR and SNCR.

[0003] At present, the SCR technology is the most widely used tail gas denitration technology. Under the action of a catalyst, the SCR system selectively reacts ammonia (NH 3 ) and oxygen (O 2 ) with NOx in the gas turbine exhaust gas to form molecular nitrogen (N 2 ) and water (H 2 O), thereby reducing nitrogen oxide emissions.

[0004] Silica-containing tailings are by-products after the exploitation and utilization of silica ore, and the annual discharge can reach 3 to 4 million tons. In the prior art, nitric acid is used to leach SiO 2 in the silica-containing tailings, and then active components are loaded to prepare an SCR flue gas denitration catalyst. However, this type of method uses a large amount of acid, generates a large amount of waste acid solution containing metal ions during the treatment process, brings the problem of purification treatment of secondary sewage, and is difficult to implement industrially. Summary of the Invention

[0005] Object of the Invention: The first object of the present invention is to provide a gas turbine high-temperature SCR flue gas denitration catalyst that makes full use of silicon-containing tailings; the second object of the present invention is to provide a preparation method of the gas turbine high-temperature SCR flue gas denitration catalyst, which does not require acidolysis treatment, does not produce a large amount of waste liquid, and avoids secondary pollution.

[0006] Technical Solution: The gas turbine high-temperature SCR flue gas denitration catalyst of the present invention comprises a carrier silicon-containing tailings, an active component, and an assistant; the silicon-containing tailings contain SiO 2 , K 2 O, CaO, MgO, Al 2 O 3 and Fe 2 O 3 , wherein the content of SiO 2 is 20-25 wt%, and SiO 2 and Al 2 O 3 , Fe 2 O 3 form a SiO 2 -Al 2 O 3 - Fe 2 O 3 mixed carrier.

[0007] The silicon-containing tailings are produced in Zhangye area and contain SiO 2 , K 2 O, CaO, MgO, Al 2 O and Fe 2 O 3 ; wherein SiO 2 and Al 2 O 3 , Fe 2 O 3 form a SiO 2 -Al 2 O 3 -Fe 2 O 3 mixed carrier. The mixed carrier catalyst has stronger surface acidity and a wider active temperature window than a single carrier catalyst. In addition, Al 2 O 3 , Fe 2 O 3 itself has certain catalytic activity and can also improve the catalyst activity; the doping of basic oxides such as K 2 O, CaO, and MgO not only makes the active component more evenly dispersed on the catalyst carrier surface, which is beneficial to increasing the catalyst specific surface area, but also can improve the alkali resistance of the catalyst.

[0008] Preferably, the content of the silicon-containing tailing slag is 80-90 wt%, the content of the active component is 5-10 wt%, and the content of the additive is 5-10 wt%.

[0009] Preferably, the content of K 2 O is 0.3-0.5 wt%, the content of CaO is 0.6-0.8 wt%, the content of MgO is 0.3-0.6 wt%, and the content of Al 2 O 3 is 1.4-1.7 wt%, and the content of Fe 2 O 3 is 1.3-1.6 wt%.

[0010] The function of the additive is to increase the redox ability of the active component through the charge transfer interaction with the active component. Preferably, the additive is indium oxide.

[0011] The function of the active component is to accelerate the removal efficiency of nitrogen oxides through redox reactions during the NH 3 -SCR removal of NOx process. Preferably, the active component is copper oxide.

[0012] The preparation method of the high-temperature SCR flue gas denitration catalyst of the gas turbine described in the present invention includes the following steps:

[0013] (1) Pretreatment of silicon-containing tailing slag: The silicon-containing tailing slag is crushed, ball-milled, and sieved to obtain silicon-containing tailing slag powder;

[0014] (2) Preparation of the catalyst: The active component and the additive are added with water to prepare a mixed solution, and the silicon-containing tailing slag powder obtained in step (1) is added to the mixed solution. After ultrasonic treatment, stirring, impregnation, drying, and calcination, it is cooled to obtain a high-temperature denitration catalyst with the silicon-containing tailing slag as the carrier.

[0015] Preferably, in step (2), the calcination temperature is 600-700 °C, and the calcination time is 4-6 h.

[0016] Preferably, in step (2), the drying temperature is 110-115 °C, and the drying time is 36-48 h.

[0017] Preferably, in step (1), the particle size of the silicon-containing tailing slag powder is 30-100 mesh.

[0018] Preferably, in step (2), the heating rate of the calcination is 8-10 °C / min.

[0019] Preferably, in step (1), the ball-milling time is 20-60 minutes.

[0020] Invention mechanism: The silicon-containing tailings are waste residues abandoned after the exploitation and utilization of silicon mines, and their compositions vary due to different mineral compositions in different regions. In Zhangye area, due to the rich silicon mines, the contents of SiO 2 、Al 2 O 3 、Fe 2 O 3 、K 2 O, CaO and MgO in the silicon-containing tailings are relatively high. Therefore, as a carrier of the catalyst, SiO 2 in the silicon-containing tailings reacts with Al 2 O 3 、Fe 2 O 3 to form a SiO 2 -Al 2 O 3 - Fe 2 O 3 mixed carrier. The catalyst with the mixed carrier has stronger surface acidity and a wider active temperature window than the catalyst with a single carrier. In addition, Al 2 O 3 、Fe 2 O 3 itself has a certain catalytic activity and can also improve the catalyst activity. The doping of K 2 O, CaO and MgO can make the active components disperse more evenly on the surface of the catalyst carrier, which is beneficial to increasing the specific surface area of the catalyst.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: (1) The catalyst makes full use of components such as SiO 2 、Al 2 O 3 、Fe 2 O 3 、K 2 O, CaO, MgO in the silicon-containing tailings, rather than mainly using the silicon components therein, will not produce residues, the utilization rate of the silicon-containing tailings is greatly improved, the catalyst has high activity and a wide active temperature window, and can maintain high denitrification activity at 400-600 °C; (2) The catalyst uses the silicon-containing tailings as the carrier, only needs to load copper oxide and indium oxide, and does not need secondary loading, so the preparation cost of the catalyst is low. (3) The pretreatment process of the silicon-containing tailings is simple and easy to operate. It only needs to crush, ball-mill and screen the silicon-containing tailings to a certain particle size for standby, without acidolysis treatment, and will not produce a large amount of waste liquid, avoiding secondary pollution. Brief description of the drawings

[0022] Figure 1 It is a test chart of the catalytic activity of the catalyst sample prepared in Example 1;

[0023] Figure 2Catalytic activity test chart of the catalyst sample prepared in Example 2;

[0024] Figure 3 Catalytic activity test chart of the catalyst sample prepared in Example 3;

[0025] Figure 4 Catalytic activity test chart of the catalyst sample prepared in Comparative Example 1. Detailed implementation manners

[0026] The technical solution of the present invention will be further described below in conjunction with the embodiments. Example 1

[0027] For the high-temperature SCR flue gas denitration catalyst of the present invention, the content of silicon-containing tailings in the carrier is 80 wt%, the content of the active component CuO is 10 wt%, and the content of the promoter In 2 O 3 is 10 wt%. Among them, the content of SiO 2 in the silicon-containing tailings is 22.7 wt%, the content of K 2 O is 0.3 wt%, the content of CaO is 0.6 wt%, the content of MgO is 0.3 wt%, and the content of Al 2 O 3 is 1.4 wt%, and the content of Fe 2 O 3 is 1.3 wt%. Its preparation method includes the following steps:

[0028] (1) Pretreatment of silicon-containing tailings:

[0029] After crushing and ball-milling the silicon-containing tailings, screen them, and take the powder with a particle size of 40-60 mesh for standby;

[0030] (2) Preparation of the catalyst by ultrasonic impregnation method:

[0031] Take 20 g of the silicon-containing tailings powder obtained in step (1), 7.6 g of Ce(NO 3 ) 2 ·3H 2 O (Sinopharm, AR), 2.9 g of In(NO 3 ) 3 ·xH 2 O (Aladdin, AR), dissolve them in 80 mL of deionized water, after ultrasonic treatment for 15 min, impregnate for 6 h under the condition of rapid stirring at 1800 r / min, dry at 110°C for 36 h, heat up to 700°C at a rate of 10°C / min in an air atmosphere and keep it for calcination for 4 h, and obtain the catalyst sample after natural cooling. Example 2

[0032] The high-temperature SCR flue gas denitration catalyst of the present invention has a carrier containing 85 wt% of silicon-containing tailings, 7.5 wt% of active component CuO, and 7.5 wt% of promoter In 2 O 3 content. Among them, the SiO 2 content in the silicon-containing tailings is 23.4 wt%, the K 2 O content is 0.4 wt%, the CaO content is 0.7 wt%, the MgO content is 0.5 wt%, and the Al 2 O 3 content is 1.5 wt%, and the Fe 2 O 3 content is 1.5 wt%. Its preparation method includes the following steps:

[0033] (1) Pretreatment of silicon-containing tailings:

[0034] After crushing and ball-milling the silicon-containing tailings, sieve them and take the powder with a particle size of 40 - 60 mesh for standby;

[0035] (2) Preparation of the catalyst by ultrasonic impregnation method:

[0036] Take 20 g of the silicon-containing tailings powder obtained in step (1), 5.4 g of Ce(NO 3 ) 2 ·3H 2 O (Sinopharm, AR), 2.1 g of In(NO 3 ) 3 ·xH 2 O (Aladdin, AR), dissolve them in 80 mL of deionized water, after ultrasonic treatment for 15 min, impregnate for 6 h under the condition of rapid stirring at 1800 r / min, dry at 110°C for 36 h, heat up to 700°C at a rate of 10°C / min in an air atmosphere, keep the temperature for 4 h, and obtain the catalyst sample after natural cooling. Example 3

[0037] The high-temperature SCR flue gas denitration catalyst of the present invention has a carrier containing 90 wt% of silicon-containing tailings, 5 wt% of active component CuO, and 5 wt% of promoter In 2 O 3 content. Among them, the SiO 2 content is 23.9 wt%, the K 2 O content is 0.5 wt%, the CaO content is 0.8 wt%, the MgO content is 0.6 wt%, and the Al 2 O 3 content is 1.7 wt%, and the Fe 2 O 3The content is 1.6 wt%; its preparation method includes the following steps:

[0038] (1) Pretreatment of silicon-containing tailings:

[0039] Crush and ball-mill the silicon-containing tailings, then screen them, and take the powder with a particle size of 40-60 mesh for standby;

[0040] (2) Prepare the catalyst by ultrasonic impregnation method:

[0041] Take 20 g of the silicon-containing tailings powder obtained in step (1), 3.3 g of Ce(NO 3 ) 2 ·3H 2 O (Sinopharm, AR), 1.3 g of In(NO 3 ) 3 ·xH 2 O (Aladdin, AR), dissolve them in 80 mL of deionized water, after ultrasonic treatment for 15 min, impregnate for 6 h under the condition of rapid stirring at 1800 r / min, dry at 110 °C for 36 h, heat up to 700 °C at a rate of 10 °C / min in an air atmosphere and keep it for calcination for 4 h, and obtain the catalyst sample after natural cooling.

[0042] Comparative Example 1

[0043] On the basis of Example 1, use ordinary SiO 2 to replace the silicon-containing tailings, and keep the other conditions unchanged.

[0044] Catalyst catalytic activity test

[0045] Carry out activity tests on the catalyst samples obtained in Examples 1-3 and Comparative Example 1. The catalyst activity is tested in a denitration catalyst evaluation device, and the reaction product concentration is detected online by a flue gas analyzer; typical simulated flue gas conditions are: 500 ppm NO, 500 ppm NH 3 , 7.5 vol% O 2 , N 2 is the balance gas, the gas flow rate is 1000 ml / min, and the space velocity is 36000 h -1 ; the denitration catalyst evaluation device is produced by Tianjin Xianquan Company, model WFS-3015; the flue gas analyzer is produced by German MRU Company, model MGA-5; obtain the NOx (NOx is NO and NO Figures 1 to 4 ) removal rate-temperature curve as shown in 2 .

[0046] It can be seen from Figure 1 that the denitration efficiency of the catalyst sample prepared in Example 1 reaches 92.3% at 350 °C and 95.6% at 400 °C.

[0047] From Figure 2 it can be seen that the denitrification efficiency of the catalyst sample reaches 91% at 350 °C and 95% at 400 °C;

[0048] From Figure 3 it can be seen that the denitrification efficiency of the catalyst sample reaches 90.1% at 350 °C and 94.6% at 400 °C;

[0049] From Figure 4 it can be seen that the denitrification efficiency of the catalyst sample reaches 75% at 350 °C and 76% at 400 °C.

[0050] Thus, it can be seen that using silicon-containing tailings as the carrier can significantly improve the denitrification efficiency of the catalyst.

[0051] The preparation method of the high-temperature SCR flue gas denitrification catalyst using silicon-containing tailings as the carrier according to the present invention is simple and easy to operate, has a high utilization rate of silicon-containing tailings, effectively solves the problems of resource waste and environmental pollution caused by the rough utilization of silicon-containing tailings, and broadens the application field of silicon-containing tailings; the catalyst prepared by the method of the present invention has high activity and a wide active temperature window, and can maintain a high denitrification activity at 400-600 °C.

Claims

1. A high-temperature SCR flue gas denitration catalyst for gas turbines, characterized in that, It includes a carrier containing silicon tailings, an active component, and a promoter; the silicon tailings contain SiO 2 , K 2 O, CaO, MgO, Al 2 O 3 and Fe 2 O 3 , where the SiO 2 content is 20 - 25 wt%, and SiO 2 and Al 2 O 3 , Fe 2 O 3 form a SiO 2 -Al 2 O 3 - Fe 2 O 3 mixed carrier; the active component is copper oxide; the promoter is indium oxide; the content of the silicon tailings is 80 - 90 wt%, the content of the active component is 5 - 10 wt%, and the content of the promoter is 5 - 10 wt%.

2. The high-temperature SCR flue gas denitration catalyst for gas turbines according to claim 1, characterized in that, The K 2 O content is 0.3 to 0.5 wt%, the CaO content is 0.6 to 0.8 wt%, the MgO content is 0.3 to 0.6 wt%, and the Al 2 O 3 content is 1.4 to 1.7 wt%, and the Fe 2 O 3 content is 1.3 to 1.6 wt%.

3. A preparation method of the high-temperature SCR flue gas denitration catalyst for gas turbines according to claim 1 or 2, characterized in that, comprises the following steps: (1) Pretreatment of silicon-containing tailings: The silicon-containing tailings are crushed, ball-milled, and screened to obtain silicon-containing tailings powder; (2) Preparation of the catalyst: The active components and additives are mixed with water to prepare a mixed solution. The silicon-containing tailings powder obtained in step (1) is added to the mixed solution. After ultrasonic treatment, stirring, impregnation, drying, and calcination, it is cooled to obtain a high-temperature denitration catalyst with silicon-containing tailings as the carrier.

4. The preparation method of the high-temperature SCR flue gas denitration catalyst for gas turbines according to claim 3, characterized in that, in step (2), the calcination temperature is 600-700 °C and the calcination time is 4-6 h.

5. The preparation method of the high-temperature SCR flue gas denitration catalyst for gas turbines according to claim 3, characterized in that, in step (2), the drying temperature is 110-115 °C and the drying time is 36-48 h.

6. The preparation method of the high-temperature SCR flue gas denitration catalyst for gas turbines according to claim 3, characterized in that, in step (1), the particle size of the silicon-containing tailings powder is 30-100 mesh.

7. The preparation method of the high-temperature SCR flue gas denitration catalyst for gas turbines according to claim 3, characterized in that, in step (2), the heating rate of the calcination is 8-10 °C / min.

Images