An electrically heatable denitration catalyst and a method for applying the same

Abstract

The application discloses an electrically heatable denitration catalyst and an application method thereof. The denitration catalyst comprises a conductive foam substrate and a catalytic component loaded on the conductive foam substrate, and is characterized in that the denitration catalyst is prepared through the following steps: (1) dissolving soluble metal salts corresponding to metal elements of the catalytic component of the denitration catalyst in water to obtain a hydrothermal reaction solution; (2) placing the conductive foam substrate into the hydrothermal reaction solution obtained in the step (1) and performing a hydrothermal reaction in a hydrothermal reaction kettle to in-situ grow the soluble metal salts on the surface of the conductive foam substrate, thereby obtaining a catalyst precursor; and (3) drying the catalyst precursor and then calcining the catalyst precursor to obtain the denitration catalyst. The catalyst disclosed by the application has good denitration activity and stability for low-temperature flue gas.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of industrial waste gas treatment and the development and research of green and efficient low-temperature SCR catalysts, and more particularly relates to an electrically heatable denitration catalyst and an application method thereof, which is mainly applied to low-temperature SCR denitration in coal-fired power plants or coking plants. BACKGROUND

[0002] Nitrogen oxides (NO x ) are one of the main atmospheric pollutants, an important factor in the formation of acid rain, one of the important precursors of ozone and photochemical smog, and an important cause of regional ultra-fine particle (PM2.5) pollution and haze. Selective catalytic reduction technology (Selective catalytic reduction, NH3-SCR) with NH3 as a reducing agent is the most widely used nitrogen oxide (NO x ) purification technology, and a denitration catalyst is an important core of NH3-SCR denitration technology.

[0003] In recent years, coal power has implemented ultra-low emission, and the total amount of atmospheric pollution emissions in non-power industries ranks first. The pollution control requirements of flue gas in non-power industries such as steel, non-ferrous metals, cement, and glass are becoming more and more stringent. The flue gas temperature of non-power industrial furnaces is mostly less than 200℃, and the flue gas temperature after dust and desulfurization is less than 150℃. Therefore, the NH3-SCR catalyst must have high catalytic activity for ultra-low temperature (<150℃) flue gas, be able to effectively avoid the influence of dust and SO2 on the performance of the catalyst, prolong the service life of the catalyst, and save energy consumption due to the process of reheating the flue gas. In view of the actual needs of ultra-low emission and low-temperature flue gas treatment, the research and application of low-temperature denitration technology are increasingly urgent, and it is hoped to provide a foam metal-based ultra-low-temperature catalyst that can solve the above problems and adapt to the working conditions.

[0004] CN 112999987 A discloses an electrically heatable monolithic metal-based catalytic reactor and a preparation method thereof. The specific steps are as follows: (1) FeCrAl metal wires are made into a multi-layer spiral structure in the radial direction to obtain a monolithic metal catalytic reactor substrate, and an Al2O3 whisker layer is oxidized on the FeCrAl metal substrate by air oxidation treatment; (2) an Al2O3 carrier coating layer is coated on the oxidized substrate; (3) the required active components are loaded on the metal substrate with the carrier coating layer to prepare a monolithic catalyst; and (4) the prepared monolithic metal-based catalyst is fixed in an insulating ceramic tube to prepare the electrically heatable monolithic metal-based catalytic reactor of the application. However, since an Al2O3 carrier coating layer needs to be coated on the metal substrate, the preparation is complex, and the loading of active components may be unstable.

[0005] CN 106423163 A discloses a monolithic catalyst and its preparation method and application, which comprises a foamed aluminum metal substrate and a hydrotalcite-like structure catalyst layer; the foamed aluminum metal substrate has a porous channel structure, and the hydrotalcite-like structure catalyst layer is located on the surface of the foamed aluminum metal substrate and in the porous channel structure; the foamed metal substrate has high heat transfer capacity, and the reaction heat of the exothermic reaction system can be quickly removed, which is beneficial to improve the conversion rate and the selectivity of the target product; however, similar to the ordinary coated catalyst, the catalyst itself does not have a temperature changing function, and the energy consumption for raising the flue gas temperature is still needed to make the flue gas reach the target active temperature window. SUMMARY

[0006] The purpose of the present application is to provide an electrically heatable denitration catalyst and its application method, which has good denitration activity and stability for low-temperature flue gas.

[0007] To achieve the first aspect of the above-mentioned purpose, the present application provides a denitration catalyst adopting the following technical solution:

[0008] An electrically heatable denitration catalyst, which comprises a conductive foam substrate and a catalytic component loaded on the conductive foam substrate, characterized in that the denitration catalyst is prepared by the following steps:

[0009] (1) dissolving soluble metal salts corresponding to metal elements of the catalytic component of the denitration catalyst in water to obtain a hydrothermal reaction solution;

[0010] (2) placing the conductive foam substrate into the hydrothermal reaction solution obtained in step (1) and sealing to perform a hydrothermal reaction, so that the soluble metal salts grow in situ on the surface of the conductive foam substrate to form a catalyst precursor;

[0011] (3) drying the catalyst precursor and calcining to obtain the denitration catalyst.

[0012] In step (1) of the present application, soluble metal salts corresponding to metal elements of the catalytic component of the denitration catalyst are dissolved in water to obtain a hydrothermal reaction solution. In an embodiment, the catalytic component comprises a first active component A, a second active component B and an additive C, and the precursor salts (i.e. soluble metal salts corresponding to metal elements) of the catalyst active component A and the active component B and the precursor salt (i.e. soluble metal salt corresponding to metal element) of the additive C are used as raw materials and dissolved in water, for example, dissolved in water according to the proportion of the corresponding metal elements in the catalytic component, to configure a hydrothermal reaction solution for subsequent hydrothermal reaction.

[0013] In an embodiment, the first active component A is an oxide of metal manganese, and the corresponding soluble precursor salt thereof includes but is not limited to manganese nitrate, manganese acetate, manganese sulfate, manganese chloride. In an embodiment, the second active component B is an oxide of cerium or lanthanum, preferably cerium oxide, and the corresponding soluble precursor salt thereof includes but is not limited to cerium nitrate, cerium nitrate, cerium ammonium nitrate, cerium carbonate, cerium chloride, lanthanum nitrate, lanthanum chloride.

[0014] In an embodiment, the auxiliary C is an oxide of one or more of tungsten, molybdenum, antimony, niobium, cobalt, iron, preferably an oxide of antimony and niobium, and the corresponding soluble precursor salt thereof includes but is not limited to ammonium metatungstate, ammonium tungstate, ammonium paratungstate, ammonium heptamolybdate, ammonium molybdophosphate, ammonium molybdate, antimony acetate, antimony chloride, niobium oxalate, ammonium niobium oxalate, cobalt nitrate, cobalt chloride, iron nitrate, iron chloride.

[0015] In an embodiment, in the hydrothermal reaction solution, the content of the metal element corresponding to the first active component A is 0.08-0.2 mol / L, such as 0.1 mol / L, 0.12 mol / L, 0.15 mol / L or 0.18 mol / L, the content of the metal element corresponding to the second active component B is 0.05-0.12 mol / L, such as 0.06 mol / L, 0.08 mol / L, 0.1 mol / L or 0.11 mol / L, and the content of the metal element corresponding to the auxiliary C is 0.02-0.06 mol / L, such as 0.03 mol / L, 0.04 mol / L or 0.05 mol / L.

[0016] In an embodiment, in the denitration catalyst, the catalytic component accounts for 29-72%, such as 30%, 36%, 40%, 50%, 60%, 65% or 70%; in an embodiment, in the catalyst, the first active component accounts for 10-25%, such as 12%, 15%, 18%, 20% or 23%, the second active component accounts for 15-35%, such as 18%, 20%, 25%, 30% or 33%, and the auxiliary accounts for 4-12%, such as 5%, 7%, 10% or 11%.

[0017] In step (2) of the present application, the conductive foam substrate is placed in the hydrothermal reaction solution for hydrothermal reaction. In an embodiment, the conductive foam substrate is a foam metal or a graphene foam; wherein the foam metal can be one of a foam aluminum, a foam copper, a foam nickel.

[0018] In an embodiment, the conductive foam substrate is a foam metal, and before the hydrothermal reaction, the foam metal is pretreated with an alkali solution to obtain a foam metal with etched surface. The alkali solution can be one or more of sodium hydroxide, sodium bicarbonate, and ammonia water; in an embodiment, the pH of the alkali solution ranges from 8 to 13, such as 8, 9, 10, or 12.

[0019] In an embodiment, in step (1), the hydrothermal reaction solution further disperses graphene oxide, and the concentration of the graphene oxide is 0.5-4 mg / mL, such as 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 3 mg / mL, or 3.5 mg / mL; research has found that, in combination with the electric heating characteristics of the foam metal of the present application, the catalytic activity and thermal conductivity of the obtained catalyst are both improved after the use of graphene oxide.

[0020] According to the denitration catalyst of the present application, in an embodiment, the conductive foam substrate is a graphene foam, which is a self-supporting three-dimensional graphene foam and is well known in the art, such as a commercially available self-supporting three-dimensional graphene foam, for example, a self-supporting three-dimensional graphene foam available from Shanghai Hedi Tong Nanometer Technology Co., Ltd. Research has found that the graphene foam used in the present application further has good electron transport performance and adsorption performance, faster temperature rise response, higher firmness of the catalyst after in-situ growth on its surface, and high reaction efficiency.

[0021] In an embodiment, in step (2), the hydrothermal reaction conditions are as follows: temperature 120-160℃, such as 130 or 150℃, and reaction time 8-12 h, such as 10 h. The hydrothermal reaction can be carried out in a polytetrafluoroethylene hydrothermal reaction kettle.

[0022] In step (3) of the present application, the catalyst precursor is dried to remove water and then calcined to obtain the denitration catalyst; wherein, during the drying and water removal, the catalyst precursor can be placed in a 100℃ oven for drying for 10-24 h, and the specific drying is well known in the art, which will not be described here. In an embodiment, in step (3), the calcination conditions are as follows: calcination temperature is 450-650℃, such as 500, 550, or 600℃, and calcination time is 3-8 h, such as 4 or 6 h.

[0023] To achieve the second aspect of the above-mentioned application purpose, the present application further provides a method for using the above-mentioned denitration catalyst, which comprises the following steps:

[0024] a. Catalyst assembly: placing the denitration catalyst in an insulating ceramic shell to form a catalyst module, and then placing the catalyst module in a catalytic reactor and connecting an external power source through a wire;

[0025] b. Catalyst activation: fresh catalyst is first run by electrically heating the catalyst to 280-330°C for 6-12h to activate the active components of the catalyst;

[0026] c. Catalyst running: for low temperature flue gas with temperature below 150°C, such as in the range of 40-150°C, the catalyst is heated by electric heating to above 150°C to catalyze the flue gas denitration reaction to improve the conversion efficiency of NOx in the low temperature flue gas; for flue gas with temperature above 150°C, such as in the range of 150-300°C, the catalyst can be directly used to catalyze the flue gas denitration reaction, and optionally the electric heating of the catalyst is stopped, i.e. the denitration reaction is directly performed without electric heating of the catalyst. Of course, for flue gas with higher temperature, it can be considered to first recover part of the heat for processing.

[0027] In the application method of the present application, when the catalyst is assembled, the catalyst is placed in an insulating ceramic shell to form a catalyst module, and the catalyst module is placed in a catalytic reactor. The module leads out positive and negative poles, and adjacent modules are connected in series. An external power source is connected through a wire, and the electrically conductive foam matrix is electrically heated to reach the activation temperature, the optimal running temperature and the in-situ regeneration temperature required for the catalytic reduction reaction.

[0028] In the application method of the present application, when the catalyst is activated, the fresh catalyst is first run by electrically heating the catalyst to 280-330°C, such as 290, 300 or 320°C, for 6-12h, such as 8 or 10h, to activate the maximum catalytic activity of the active components of the catalyst.

[0029] In the application method of the present application, when the catalyst is running, for flue gas in the range of 150-300°C, the catalyst can be directly used for denitration without electric heating; for low temperature flue gas in the range of 40-150°C, the catalyst can be heated to 150°C by electric heating to catalyze the reaction, thereby improving the conversion efficiency of NOx in the low temperature flue gas.

[0030] In one embodiment, the application method further comprises step d, catalyst regeneration: during the running process, when the denitration efficiency / initial denitration efficiency <0.8, i.e. when the denitration efficiency of the catalyst is lower than 80% of the initial denitration efficiency at the same catalyst running temperature, the catalyst temperature is raised to above 300°C, such as 300-330°C, for continuous running of 8-12h, so as to regenerate, for example, to in-situ thermal decomposition of impurities such as ammonium bisulfate deposited on the surface of the catalyst.

[0031] In the present application, unless otherwise specified, the percentages appearing in the text are mass percentages.

[0032] The denitration catalyst of the present application takes the conductive foam substrate as the framework or catalyst carrier, and grows the catalytic components in situ on the substrate, so that the catalyst has high activity in the temperature range of 150-420 DEG C, and the active coating has high adhesion strength and strong resistance to fly ash abrasion. For flue gas below 150 DEG C, the catalyst temperature can be increased above 150 DEG C by electric heating of the foam substrate to realize the denitration function. For the slow failure of the catalyst at low temperature due to the deposition of ammonium bisulfate, the ammonium bisulfate can be decomposed by periodically heating the catalyst to 330 DEG C to restore the catalytic activity and realize the long-period operation stability of the catalyst.

[0033] The catalyst of the present application has a wide temperature window of 150-420 DEG C for denitration, and can realize rapid heating of the catalyst by electric heating of the foam substrate, adapt to lower temperature flue gas denitration, and realize the regeneration ability of the catalyst after failure. It can be applied to the flue gas NOx purification of waste incineration, cement, steel and the like. x

[0034] Compared with the prior art, the present application has the following advantages:

[0035] 1) The unique manganese-based composite oxide formula of the catalyst has high activity and can meet the denitration requirement at 150-300 DEG C.

[0036] 2) The in-situ synthesis method makes the adhesion of the catalytically active coating to the foam substrate high and the abrasion resistance strong, and the coating is not easy to fall off under the scouring of fly ash.

[0037] 3) The foam substrate has the ability of electric conduction and heat conduction, and the temperature change can be realized by self-heating of the catalyst. Through electric heating assistance, the denitration requirement at 40-150 DEG C can be met. This method only needs to heat the catalyst, avoids heating the low-temperature flue gas after wet desulfurization by GGH, and saves the cost and operating cost of additional GGH heat exchange device.

[0038] 4) There is still a small amount of SO2 in the flue gas after desulfurization, and ammonium bisulfate will be generated in the pores of the catalyst after a certain period of operation at low temperature. The ammonium bisulfate can be directly decomposed in situ by self-heating of the catalyst, so that the catalyst restores to the initial activity, thereby prolonging the service life of the catalyst. If the traditional catalyst is regenerated, the flue gas temperature needs to be increased, which causes waste of energy consumption and slow response speed, and the external flue gas cannot completely remove the ammonium bisulfate in the pores, so the regeneration effect is limited.

[0039] ​5) If the front end desulfurization device of the denitration appears failure, a large amount of SO2 gas enters the denitration reactor, causing a large amount of ammonium bisulfate to be generated on the surface of the catalyst and the catalyst to be rapidly deactivated. The catalyst of the present application can be rapidly regenerated after being powered on, and the denitration efficiency decay rate is lower when the catalyst is operated at low temperature again, and the flue gas regeneration effect is better than that of the traditional catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 SEM image of the catalyst prepared in Example 1;

[0041] Figure 2 Schematic diagram of the catalyst assembly of Example 1. DETAILED DESCRIPTION

[0042] The present application will be further described below in conjunction with examples, but the present application is not limited to the listed examples.

[0043] Example 1:

[0044] (1) Pretreatment of aluminum foam (size 5x5x5 cm, same below): The aluminum foam is pretreated with a sodium hydroxide solution with pH = 12, the aluminum foam is immersed in the alkaline solution, the surface of the aluminum foam is etched to reduce the weight of the aluminum foam by about 3%, and the etched aluminum foam is washed several times with deionized water and dried at 110°C for 10h.

[0045] (2) Preparation of hydrothermal reaction solution: 0.1 mol / L manganese acetate, 0.08 mol / L cerium nitrate, 0.01 mol / L antimony acetate, and 0.01 mol / L niobium oxalate solution are prepared;

[0046] (3) In-situ growth of active components: the foam metal obtained in step (1) is placed in the hydrothermal reaction solution prepared in step (2), poured into a polytetrafluoroethylene hydrothermal kettle, sealed and reacted at 150°C for 8h to allow the active components to grow in-situ on the surface of the foam metal. The foam metal catalyst after reaction is placed in a 100°C oven for drying for 10h, and then placed in a muffle furnace for calcination at 550°C for 5h, and the obtained catalyst is as shown in Figure 1

[0047] (4) Catalyst installation: as shown in Figure 2 , the catalyst 1 obtained in step (3) is placed in an insulating ceramic tube 2, and the ceramic tube 2 is placed in the reactor to facilitate better gas flow through the catalyst during reaction. The upper end and the lower end of the catalyst 1 are respectively welded with wires to connect an external power source 3. By electrically heating the catalyst, the activation temperature, the optimal operating temperature and the in-situ regeneration temperature required for the catalytic reduction reaction are achieved.

[0048] ​(5) Catalyst operation: fresh catalyst is activated for the first time, the catalyst temperature is raised to 330°C and continuously operated for 6h, then reduced to 150°C for low temperature operation. During the operation, when the denitration efficiency / initial denitration efficiency < 0.8, the catalyst temperature is raised to 330°C and continuously operated for 8h, and the ammonium bisulfate deposited on the surface of the catalyst is fully thermally decomposed in situ at high temperature before low temperature operation.

[0049] Comparative Example 1:

[0050] The same as the steps of Example 1, the difference is that the step (1) of the aluminum foam is replaced by a non-conductive coated substrate honeycomb cordierite ceramic, the catalyst formulation and loading are consistent, but it cannot be self-heated by electric heating.

[0051] Example 2

[0052] (1) Foam aluminum pretreatment: use sodium bicarbonate with pH = 10 to pretreat the foam aluminum, immerse the foam aluminum in the alkaline solution, etch the surface of the foam aluminum to reduce the weight of the foam aluminum by about 1%, and then rinse the etched foam aluminum with deionized water several times and dry at 110°C for 10h.

[0053] (2) Preparation of hydrothermal reaction solution: prepare a hydrothermal reaction solution containing dispersed graphene oxide, which contains 0.2mol / L manganese acetate, 0.1mol / L cerium nitrate, 0.02mol / L antimony acetate, 0.02mol / L niobium oxalate, and 1.5mg / L graphene oxide;

[0054] (3) In-situ growth of active components: place the foam metal obtained in step (1) in the hydrothermal reaction solution prepared in step (2), pour it into a polytetrafluoroethylene hydrothermal kettle, seal it and react at 120°C for 8h to grow active components in-situ on the surface of the foam metal. After reaction, the foam metal catalyst is placed in a 100°C oven for drying for 10h, and then placed in a muffle furnace at 500°C for calcination for 8h.

[0055] (4) Catalyst installation: as shown in Figure 2 , the catalyst 1 obtained in step (3) is placed in an insulating ceramic tube 2, and the ceramic tube 2 is placed in a reactor to facilitate better gas flow through the catalyst during reaction. The upper and lower ends of the catalyst 1 are respectively welded with wires to connect an external power supply 3. By electric heating of the catalyst, the activation temperature required for catalytic reduction reaction, the optimal operation temperature and the in-situ regeneration temperature are achieved.

[0056] (5) Catalyst operation: fresh catalyst is activated for the first time, the catalyst temperature is raised to 330°C and continuously operated for 6h, and then reduced to 150°C for low temperature operation. During the operation, when the denitration efficiency / initial denitration efficiency < 0.8, the catalyst temperature is raised to 330°C and continuously operated for 8h, and then the ammonium bisulfate deposited on the surface of the catalyst is fully thermally decomposed at high temperature in situ, and then low temperature operation is carried out.

[0057] Example 3

[0058] (1) Preparation of hydrothermal reaction solution: 0.1 mol / L manganese acetate, 0.08 mol / L cerium nitrate, 0.01 mol / L antimony acetate, and 0.01 mol / L niobium oxalate solutions are prepared;

[0059] (2) In-situ growth of active component: graphene foam (self-supporting three-dimensional graphene foam purchased from Shanghai Hedi Technology Co., Ltd., size 5x5x5 cm, same below) is placed in the hydrothermal reaction solution prepared in step (1), poured into a polytetrafluoroethylene hydrothermal kettle, sealed and reacted at 120°C for 8h to grow the active component in-situ on the surface of the graphene foam. The graphene foam catalyst after reaction is dried in a 100°C oven for 12h, and then calcined in a muffle furnace at 600°C for 6h.

[0060] (3) Catalyst installation: as shown in Figure 2 , catalyst 1 obtained in step (3) is placed in an insulating ceramic tube 2, and the ceramic tube 2 is placed in the reactor to facilitate better gas flow through the catalyst during the reaction. The upper end and the lower end of the catalyst 1 are respectively welded with wires to connect an external power supply 3. By electrically heating the catalyst, the activation temperature required for the catalytic reduction reaction, the optimal operation temperature and the in-situ regeneration temperature are achieved.

[0061] (4) Catalyst operation: fresh catalyst is activated for the first time, the catalyst temperature is raised to 330°C and continuously operated for 6h, and then reduced to 150°C for low temperature operation. During the operation, when the denitration efficiency / initial denitration efficiency < 0.8, the catalyst temperature is raised to 330°C and continuously operated for 8h, and then the ammonium bisulfate deposited on the surface of the catalyst is fully thermally decomposed at high temperature in situ, and then low temperature operation is carried out.

[0062] Comparative Example 3

[0063] The steps are the same as those in Example 3, except that the graphene foam in step (1) is replaced by a non-conductive coated matrix honeycomb cordierite ceramic, and the catalyst formulation and loading are consistent, but the self-heating cannot be achieved by electric heating.

[0064] Example 4

[0065] (1) Hydrothermal reaction solution preparation: 0.1 mol / L manganese acetate, 0.08 mol / L lanthanum nitrate, 0.01 mol / L cobalt nitrate, 0.01 mol / L niobium oxalate solution were prepared;

[0066] (2) Active component in-situ growth: The graphene foam was placed in the hydrothermal reaction solution prepared in step (1), poured into a polytetrafluoroethylene hydrothermal kettle, sealed, and reacted at 140°C for 6h to allow the active component to grow in-situ on the surface of the graphene foam. The graphene foam catalyst after reaction was placed in a 100°C oven for drying for 10h, and then placed in a muffle furnace for calcination at 500°C for 5h.

[0067] (3) Catalyst installation: As shown in Figure 2 , catalyst 1 obtained in step (3) was placed in an insulating ceramic tube 2, and the ceramic tube 2 was placed in a reactor to facilitate better gas flow through the catalyst during the reaction. The upper end and the lower end of the catalyst 1 were respectively welded with wires to connect an external power source 3. By electrically heating the catalyst, the required activation temperature, optimal operating temperature, and in-situ regeneration temperature for the catalytic reduction reaction were achieved.

[0068] (4) Catalyst operation: When the fresh catalyst was first operated, activation was performed, and the catalyst temperature was raised to 330°C for continuous operation for 6h, and then lowered to 150°C for low-temperature operation. During the operation, when the denitration efficiency / initial denitration efficiency was less than 0.8, the catalyst temperature was raised to 330°C for continuous operation for 8h, and then the ammonium bisulfate deposited on the surface of the catalyst was fully thermally decomposed at high temperature in-situ, and low-temperature operation was performed again.

[0069] Test method:

[0070] 1. Catalyst low-temperature continuous operation time and corresponding denitration efficiency at different temperatures

[0071] Catalyst performance test: By electrically heating the catalyst of Example 1 or heating the flue gas of Comparative Example 1, the following was tested: (1) denitration efficiency at 150°C before catalyst activation (efficiency a), (2) denitration efficiency / initial denitration efficiency when low-temperature continuous operation was performed until the denitration efficiency / initial denitration efficiency was less than 0.8 (time a), (3) denitration efficiency after the temperature was raised to 330°C for continuous operation for 24h based on test condition (2) (efficiency b), (4) denitration efficiency when the temperature was lowered to 150°C for operation after 330°C operation (efficiency c), and (5) denitration efficiency / initial denitration efficiency when low-temperature continuous operation was performed until the denitration efficiency / initial denitration efficiency was less than 0.8 based on test condition (4) (time b). The composition of the flue gas was SO2= 50 ppm, NO x = NH3= 300 ppm, O2= 8%, H2O= 20%, and N2 was the balance gas. The concentration of NO x at the inlet and outlet of the catalyst was tested by a portable infrared flue gas analyzer.

[0072] NO conversion rate:

[0073]

[0074] In the formula: is the NO concentration at the reactor inlet, ppm; x is the NO concentration at the reactor outlet, ppm. x

[0075] The results are shown in Table 1:

[0076] Table 1 De-NOx efficiency of catalysts (%)

[0077]

[0078] Table 2 Low-temperature continuous operation time of catalysts

[0079]

[0080] According to Examples 1 and 2 and Comparative Examples 1 and 2, and Examples 3 and 4 and Comparative Examples 3 and 4, it can be seen from Tables 1 and 2 that, compared with conventional catalysts with cordierite carriers, the catalysts of the present application have good long-term operation effects and long service lives; at the same time, according to Example 2, in combination with the electric heating characteristics of the foam metal of the present application, after a small amount of graphene oxide is used, the catalytic activity and the thermal conductivity and stability of the obtained catalysts are all good, and the catalysts have one effect with multiple benefits, and can basically achieve the catalytic activity and the thermal conductivity and stability of catalysts using graphene foam.​​

Claims

1. A method for applying a denitrification catalyst, characterized in that, The application method includes: a. Catalyst assembly: The denitrification catalyst is placed in an insulating ceramic shell to form a catalyst module, and then the catalyst module is placed in the catalytic reactor and connected to an external power source through wires; b. Catalyst activation: When the fresh catalyst is run for the first time, the assembled catalyst is electrically heated to 280℃-330℃ and run continuously for 6-12 hours to activate the catalyst. c. Catalyst Operation: For low-temperature flue gas below 150℃, the activated catalyst is heated to above 150℃ via electric heating to catalyze the denitrification reaction in the flue gas, thereby increasing the NO concentration in the low-temperature flue gas. x The conversion efficiency; for flue gas with a temperature above 150℃, the activated catalyst is directly used to catalyze the flue gas denitrification reaction, and optionally the catalyst is not electrically heated; The denitration catalyst comprises a conductive foam matrix and a catalytic component supported on the conductive foam matrix, and is prepared by the following steps: (1) Dissolve the soluble metal salt corresponding to the metal element of the catalytic component of the denitrification catalyst in water to obtain a hydrothermal reaction solution; (2) The conductive foam matrix is ​​placed in the hydrothermal reaction liquid obtained in step (1), and the hydrothermal reaction is carried out in a sealed manner so that the soluble metal salt grows in situ on the surface of the conductive foam matrix to obtain the catalyst precursor. (3) The catalyst precursor is dried and then calcined to obtain the denitration catalyst.

2. The application method according to claim 1, characterized in that, The application method also includes step d, catalyst regeneration: during operation, when the denitrification efficiency / initial denitrification efficiency < 0.8, the catalyst temperature is raised to 300-330℃ and operated continuously for 8-12 hours.

3. The application method according to claim 1, characterized in that, The conductive foam matrix is ​​a foam metal or graphene foam; The catalytic component includes a first active component, a second active component, and an auxiliary agent; wherein the first active component is an oxide of metallic manganese; the second active component is an oxide of cerium or lanthanum; and the auxiliary agent is one or more oxides of tungsten, molybdenum, antimony, niobium, cobalt, and iron.

4. The application method according to claim 3, characterized in that, The second active component is cerium oxide; the auxiliary agents are oxides of antimony and niobium.

5. The application method according to claim 3 or 4, characterized in that, In the hydrothermal reaction solution, the metal element content corresponding to the first active component is 0.08-0.2 mol / L, the metal element content corresponding to the second active component is 0.05-0.12 mol / L, and the metal element content corresponding to the auxiliary agent is 0.02-0.06 mol / L.

6. The application method according to claim 3, characterized in that, The conductive foam matrix is ​​foam metal, and before the hydrothermal reaction, the foam metal is pretreated with an alkaline solution to obtain surface-etched foam metal.

7. The application method according to claim 6, characterized in that, The foam metal is etched to reduce its weight by 0.5-4%.

8. The application method according to claim 6 or 7, characterized in that, The foam metal is one or more of foamed aluminum, foamed copper, and foamed nickel; The alkaline solution is one or more of sodium hydroxide, sodium bicarbonate, and ammonia.

9. The application method according to claim 8, characterized in that, The pH of the alkaline solution is 8-13.

10. The application method according to any one of claims 6-7 and 9, characterized in that, In step (1), graphene oxide is further dispersed in the hydrothermal reaction solution, and the concentration of graphene oxide is 0.5-4 mg / mL.

11. The application method according to claim 3, characterized in that, The graphene foam is a self-supporting three-dimensional graphene foam.

12. The application method according to any one of claims 1-4, 6-7, 9 and 11, characterized in that, In step (2), the hydrothermal reaction conditions are as follows: temperature 120-160℃, reaction time 8-12h.

13. The application method according to any one of claims 1-4, 6-7, 9 and 11, characterized in that, In step (3), the calcination conditions are as follows: calcination temperature is 450-650℃, and calcination time is 3-8h.

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