Device and method for enabling denitration catalyst to be subjected to rapid SCR (Selective Catalytic Reduction) reaction

Abstract

The invention belongs to the technical field of waste gas denitration treatment, and particularly discloses a device and a method for enabling a denitration catalyst to be subjected to a rapid SCR (Selective Catalytic Reduction) reaction. The device comprises an NO oxidation device, a switch and an NH3-SCR reaction device which are arranged in sequence, the NO oxidation device comprises a Pt / CeO2 catalyst, and the NH3-SCR reaction device comprises a Cu / HZSM-5 molecular sieve denitration catalyst; the device further comprises a first heating device (for heating the NO oxidation device) and a second heating device (for heating the NH3-SCR reaction device); and the second heating device is a microwave heating device. According to the device, part of NO can be oxidized into NO2 through the NO oxidation device, rapid SCR reaction is promoted to occur on the surface of a catalyst of the subsequent NH3-SCR reaction device, and therefore efficient catalytic reduction of nitric oxide under the conditions of high air speed and low temperature is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas denitration treatment, and in particular to a device and method for causing a denitration catalyst to undergo a rapid SCR reaction. Background Art

[0002] At present, the reduction of fixed-source flue gas emissions has achieved a phased success, and the reduction of mobile-source emissions has become the focus of attention, especially automobile exhaust emissions, NO emissions from diesel vehicles, etc. x It accounts for more than 80% of total automobile emissions. x ) is related to environmental problems such as acid rain, photochemical smog, greenhouse effect and ozone layer depletion. Due to the unsatisfactory low-temperature performance of current catalysts, motor vehicles emit a large amount of nitrogen oxides during the cold start phase. Therefore, it is necessary to enhance the nitrogen oxide removal performance of catalysts under low-temperature conditions to achieve environmental protection and sustainable social development.

[0003] In the selective catalytic reduction (SCR) technology, the catalyst is the core component to achieve efficient denitration reaction. SCR technology uses a catalyst in an oxygen-containing atmosphere, with ammonia, urea or hydrocarbons as reducing agents, to reduce nitrogen oxides in flue gas to non-toxic nitrogen and water. This process is usually carried out in the temperature range of 200°C to 450°C, and the denitration efficiency can reach 80% to 90%. SCR technology using NH3 as a reducing agent is currently the most widely used denitration technology, and its main reaction equation is as follows:

[0004] 4NO+4HN3+O2→4N2+6H2O

[0005] 2NO2+4NH3+O2→3N2+6H2O

[0006] At present, SCR catalysts mainly use titanium dioxide as a carrier, and add active components such as vanadium pentoxide and tungsten oxide. These components improve the activity and stability of the catalyst through synergistic effects. However, the performance of traditional SCR catalysts is poor in low-temperature environments, especially under low-sulfur or sulfur-free conditions. The catalyst is easily affected by alkali metal poisoning, resulting in decreased activity. In addition, the catalyst is prone to sintering at high temperatures, further reducing the denitrification efficiency.

[0007] To overcome these problems, researchers have developed a variety of new catalysts. For example, a low-temperature SCR denitrification catalyst based on high entropy oxides is prepared by coprecipitation and can achieve efficient denitrification reactions at lower temperatures. This catalyst uses biochar or anatase-type nano-titanium dioxide as a carrier, and the surface is loaded with high entropy co-doped nanoparticles made of a mixture of iron, manganese, cerium, tungsten and cobalt as active components. Its SCR activity exceeds 90% in the temperature range of 120°C to 180°C.

[0008] Although existing technologies have made significant progress, how to further improve the activity of catalysts under low temperature conditions remains the focus of current research. Summary of the invention

[0009] In view of this, the present invention provides a device and method for causing a denitration catalyst to undergo a rapid SCR reaction, so as to solve the problem that the existing denitration method has low activity under low temperature conditions and unsatisfactory denitration effect, and at the same time solves the problem that the catalyst is easily sintered at high temperature, resulting in reduced denitration efficiency.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] A device for causing a denitration catalyst to undergo a rapid SCR reaction, the device for causing a denitration catalyst to undergo a rapid SCR reaction comprising a NO oxidation device, a switch and an NH3-SCR reaction device arranged in sequence;

[0012] The NO oxidation device includes a Pt / CeO2 catalyst, and the NH3-SCR reaction device includes a Cu / HZSM-5 molecular sieve denitration catalyst;

[0013] The device for causing the denitration catalyst to undergo a rapid SCR reaction also includes a first heating device and a second heating device;

[0014] The first heating device heats the NO oxidation device, and the second heating device heats the NH3-SCR reaction device;

[0015] The second heating device is a microwave heating device.

[0016] Preferably, the preparation method of the Pt / CeO2 catalyst comprises the following steps:

[0017] 1) calcining a cerium source to obtain cerium oxide, and mixing the obtained cerium oxide with a solvent to obtain a carrier solution;

[0018] 2) Mixing a solution containing a platinum source with a carrier solution, drying and calcining to obtain a Pt / CeO2 catalyst.

[0019] Preferably, the cerium source in step 1) includes one or more of cerium nitrate, cerium sulfate and cerium acetate;

[0020] The platinum source in the solution containing the platinum source in step 2) includes one or more of chloroplatinic acid, platinum nitrate and platinum chloride.

[0021] Preferably, the mass ratio of platinum in the solution containing the platinum source to cerium oxide in the carrier solution in step 2) is 0.1-1.2:100;

[0022] The mixing temperature in step 2) is 60-90° C. and the mixing time is ≥6 h;

[0023] The calcination temperature in step 2) is 400-600° C., and the calcination time is 3-6 hours.

[0024] Preferably, the preparation method of the Cu / HZSM-5 molecular sieve denitration catalyst comprises the following steps:

[0025] The solution containing the copper source is mixed with the HZSM-5 molecular sieve solution, and then dried and calcined to obtain a Cu / HZSM-5 molecular sieve denitration catalyst.

[0026] Preferably, the copper source in the solution containing a copper source includes one or more of copper nitrate, copper acetate and copper sulfate;

[0027] The mass ratio of copper in the copper source-containing solution to HZSM-5 molecular sieve in the HZSM-5 molecular sieve solution is 0.5 to 6:100;

[0028] The mixing temperature is 60-90°C and the mixing time is ≥6h;

[0029] The calcination temperature is 400-600° C., and the calcination time is 3-6 hours.

[0030] Another object of the present invention is to provide a method for causing a denitration catalyst to undergo a rapid SCR reaction, comprising the following steps:

[0031] S1: Turn off the switch of the device that causes the denitration catalyst to undergo a rapid SCR reaction, pass the mixed gas into the NO oxidation device, and heat the mixed gas using the first heating device, so that the mixed gas reacts;

[0032] S2: After the reaction is stable, the switch is turned on, the mixed gas is passed into the NH3-SCR reaction device, and ammonia is passed into the NH3-SCR reaction device at the same time, and the second heating device is used to heat it to achieve a rapid SCR reaction of the denitration catalyst;

[0033] The device for causing the denitration catalyst to undergo a rapid SCR reaction is the above-mentioned device.

[0034] Preferably, the mixed gas in step S1 is a mixed gas of NO, O2 and N2, the volume concentration of NO is 700-2000 ppm, and the volume concentration of O2 is 5-10%;

[0035] The heating temperature in step S1 is 300-350°C.

[0036] Preferably, the reaction in step S2 is stabilized such that the NO oxidation conversion rate is controlled at 40-50%;

[0037] The heating in step S2 is to heat the catalyst to 60-300°C.

[0038] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0039] The active temperature window of existing low-temperature denitrification catalysts is between 150 and 280°C, which is difficult to deal with the large amount of NO generated during the cold start phase of diesel vehicles. x . The present invention uses microwave fields to provide energy to heat the catalyst, so that the catalyst is heated evenly, and adds a NO oxidation device in front of the NH3-SCR reaction device (the heating method can be conventional heating) to oxidize part of NO into NO2, thereby promoting a rapid SCR reaction on the surface of the catalyst of the subsequent NH3-SCR reaction device, thereby achieving efficient catalytic reduction of nitrogen monoxide under high space velocity and low temperature conditions. The reaction space velocity is increased, and compared with the activity of the catalyst under conventional heating conditions, the microwave-heated catalyst still has a higher activity in a low temperature environment, thereby reducing the amount of catalyst used and reducing the catalyst cost.

[0040] When the NO oxidation device is not added, the reaction on the surface of the SCR catalyst is mainly: 4NO+4NH3+O2→4N2+6H2O, which is a standard SCR reaction with a slow reaction rate. After adding the NO oxidation device, after part of NO is oxidized to NO2, by controlling the NO oxidation conversion rate, the reaction on the surface of the SCR catalyst is mainly: 2NO+4NH3+2NO2→4N2+6H2O, which is a fast SCR reaction. NO2 can form a more active intermediate species (nitro, nitrite and nitrate species and other active intermediate species) with NO on the catalyst surface. The intermediate species can react with NH3 more quickly, thereby accelerating the entire reaction process; the participation of NO2 changes the reaction path, reduces the activation energy of the reaction, makes the reaction easier, and greatly increases the reaction rate; NO2 can also synergize with NO on the catalyst surface, occupy some active sites that were originally not highly utilized, or change the electronic environment of the active sites, so that more active sites can participate in the reaction, thereby improving the overall activity of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0042] Figure 1The performance test results of catalytic reduction of NO under different space velocity conditions in Example 1 of the present invention;

[0043] Figure 2 The performance test results of catalytic reduction of NO by Example 2 of the present invention and Comparative Example 1 are shown;

[0044] Figure 3 The performance test results of catalytic reduction of NO under different heating conditions of Example 3 of the present invention and Comparative Example 2;

[0045] Figure 4 The stability evaluation results of catalytic reduction of NO under different space velocity conditions in Example 4 of the present invention are shown. DETAILED DESCRIPTION

[0046] The present invention provides a device for causing a denitration catalyst to undergo a rapid SCR reaction. The device for causing a denitration catalyst to undergo a rapid SCR reaction comprises a NO oxidation device, a switch and an NH3-SCR reaction device which are arranged in sequence.

[0047] In the present invention, the NO oxidation device includes a Pt / CeO2 catalyst, and the NH3-SCR reaction device includes a Cu / HZSM-5 molecular sieve denitration catalyst; both the Pt / CeO2 catalyst and the Cu / HZSM-5 molecular sieve denitration catalyst are prepared by an impregnation method.

[0048] In the present invention, the device for causing the denitration catalyst to undergo a rapid SCR reaction further comprises a first heating device and a second heating device.

[0049] In the present invention, the first heating device heats the NO oxidation device, and the second heating device heats the NH3-SCR reaction device.

[0050] In the present invention, the second heating device is a microwave heating device, and the first heating device can be a conventional heating device, including a tubular resistance furnace.

[0051] In the present invention, the preparation method of the Pt / CeO2 catalyst comprises the following steps:

[0052] 1) calcining a cerium source to obtain cerium oxide, and mixing the obtained cerium oxide with a solvent to obtain a carrier solution;

[0053] 2) Mixing a solution containing a platinum source with a carrier solution, drying and calcining to obtain a Pt / CeO2 catalyst.

[0054] In the present invention, the cerium source in step 1) includes one or more of cerium nitrate, cerium sulfate and cerium acetate, and also includes corresponding hydrates.

[0055] In the present invention, the platinum source in the solution containing the platinum source in step 2) includes one or more of chloroplatinic acid, platinum nitrate and platinum chloride, and also includes corresponding hydrates.

[0056] In the present invention, the molar ratio of platinum in the solution containing the platinum source in step 2) to cerium oxide in the carrier solution is 0.1-1.2:100, preferably 0.2-1:100, more preferably 0.4-0.8:100, and further preferably 0.5:100.

[0057] In the present invention, the mixing temperature in step 2) is 60-90°C, specifically 65°C, 70°C, 75°C, 80°C, 85°C; the mixing rate is preferably 400-700rpm, specifically 450rpm, 500rpm, 550rpm, 600rpm, 650rpm; the mixing time is ≥6h, specifically 6.5h, 7h, 7.5h, 8h.

[0058] In the present invention, the mixing in step 2) is preferably performed by dripping a solution containing a platinum source into a carrier solution, and the dripping rate is preferably 4 to 6 mL / min, specifically 4.2 mL / min, 4.5 mL / min, 4.8 mL / min, 5 mL / min, 5.2 mL / min, 5.5 mL / min, and 5.8 mL / min.

[0059] In the present invention, the calcination temperature in step 2) is 400-600°C, specifically 450°C, 500°C, 550°C; the calcination time is 3-6h, specifically 3.5h, 4h, 4.5h, 5h, 5.5h.

[0060] In the present invention, the preparation method of the Cu / HZSM-5 molecular sieve denitration catalyst comprises the following steps:

[0061] In the present invention, a solution containing a copper source is mixed with a HZSM-5 molecular sieve solution, and then dried and calcined to obtain a Cu / HZSM-5 molecular sieve denitration catalyst.

[0062] In the present invention, the copper source in the solution containing the copper source includes one or more of copper nitrate, copper acetate and copper sulfate, and also includes corresponding hydrates.

[0063] In the present invention, the mass ratio of copper in the solution containing the copper source to the HZSM-5 molecular sieve in the HZSM-5 molecular sieve solution is 0.5 to 6:100, preferably 1 to 5:100, and more preferably 3 to 4:100.

[0064] In the present invention, the mixing temperature is 60-90°C, specifically 65°C, 70°C, 75°C, 80°C, 85°C; the mixing rate is preferably 400-700rpm, specifically 450rpm, 500rpm, 550rpm, 600rpm, 650rpm; the mixing time is ≥6h, specifically 6.5h, 7h, 7.5h, 8h.

[0065] In the present invention, the mixing is preferably performed by dropping a solution containing a copper source into a HZSM-5 molecular sieve solution, and the dropping rate is preferably 4 to 6 mL / min, specifically 4.2 mL / min, 4.5 mL / min, 4.8 mL / min, 5 mL / min, 5.2 mL / min, 5.5 mL / min, and 5.8 mL / min.

[0066] In the present invention, the calcination temperature is 400-600°C, specifically 450°C, 500°C, 550°C; the calcination time is 3-6h, specifically 3.5h, 4h, 4.5h, 5h, 5.5h.

[0067] The present invention also provides a method for causing a denitration catalyst to undergo a rapid SCR reaction, comprising the following steps:

[0068] S1: Turn off the switch of the device that causes the denitration catalyst to undergo a rapid SCR reaction, pass the mixed gas into the NO oxidation device, and heat the mixed gas using the first heating device, so that the mixed gas reacts;

[0069] S2: After the reaction is stable, the switch is turned on, the mixed gas is passed into the NH3-SCR reaction device, and ammonia is passed into the NH3-SCR reaction device at the same time, and the second heating device is used for heating to achieve a rapid SCR reaction of the denitration catalyst. The device for causing the denitration catalyst to undergo a rapid SCR reaction is the above-mentioned device.

[0070] In the present invention, the mixed gas in step S1 is a mixed gas of NO, O2 and N2, the volume concentration of NO is 700-2000ppm, specifically 800ppm, 1000ppm, 1200ppm, 1400ppm, 1500ppm, 1600ppm, 1800ppm; the volume concentration of O2 is 5-10%, specifically 6%, 7%, 8%, 9%. NH3 is mixed with the mixed gas after the reaction through a branch, and its concentration is 200-1000ppm, specifically 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, and 900ppm; the space velocity of the mixed gas is 60000-500000mL / (g·h), specifically 80000mL / (g·h), 100000mL / (g·h), 120000mL / (g·h), 150000mL / (g·h), 180000mL / (g·h), 200000mL / (g·h), 250000mL / (g·h), 300000mL / (g·h), 350000mL / (g·h), 400000mL / (g·h), and 450000mL / (g·h).

[0071] In the present invention, after the switch in step S2 is turned on, the switch is no longer turned off when the mixed gas is subsequently introduced.

[0072] In the present invention, the heating temperature in step S1 is 300-350°C, specifically 310°C, 320°C, 330°C, or 340°C.

[0073] In the present invention, the stable NO oxidation conversion rate of the reaction in step S2 is controlled at 40-50%, specifically 42%, 44%, 45%, 46%, 48%.

[0074] In the present invention, when the device is actually used, the mixed gas is the waste gas to be treated.

[0075] In the present invention, the specific calculation formula of NO oxidation conversion rate is as follows:

[0076]

[0077] Among them, [NO2] out is the concentration of NO2 in the exhaust gas after catalysis in the NO oxidation device, [NO x ] out NO in the exhaust gas after being catalyzed in the NO oxidation device x concentration.

[0078] In the present invention, NO x The specific calculation formula of catalytic reduction conversion rate is as follows:

[0079]

[0080] Among them, [NO x ] in NO in the exhaust gas before entering the NO oxidation device x The concentration of [NO x ] out NO in the exhaust gas after being catalyzed by the NH3-SCR reaction device x concentration.

[0081] In the present invention, the heating in step S2 is to heat the catalyst to 60-300°C, specifically 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, 220°C, 250°C, or 280°C.

[0082] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0083] Example 1

[0084] Take a certain amount of cerium nitrate hexahydrate, calcine it in a muffle furnace to obtain cerium oxide, then mix the cerium oxide with water to prepare a carrier solution; dissolve chloroplatinic acid hexahydrate in water to obtain a solution containing a platinum source, then add it dropwise to the carrier solution at 5 mL / min (the mass ratio of platinum to cerium oxide is 1:100), and after ultrasonication, stir at 80°C and 500 rpm until the solution is evaporated to dryness (time is greater than 6 hours), then dry it in an oven overnight, and finally calcine at 500°C for 4 hours to obtain a Pt / CeO2 catalyst.

[0085] The HZSM-5 molecular sieve was washed, dried and calcined in sequence to complete the pretreatment, and then mixed with water to obtain a carrier solution. The copper nitrate solution was added dropwise to the carrier solution at 5 mL / min (the mass ratio of copper to HZSM-5 molecular sieve was 4:100). After ultrasonication, the solution was stirred at 80°C and 500 rpm until it evaporated to dryness (for more than 6 hours), and then dried in an oven overnight. Finally, it was calcined at 500°C for 4 hours to obtain the Cu / HZSM-5 molecular sieve denitrification catalyst.

[0086] The Pt / CeO2 catalyst was loaded into a quartz reaction tube, and both ends of the reaction tube were sealed with quartz wool to serve as a NO oxidation device, and the temperature inside the tube was controlled by a tubular resistance furnace; the Cu / HZSM-5 molecular sieve denitrification catalyst was loaded into a quartz tube to serve as an NH3-SCR reaction device, and the temperature inside the tube was controlled by a microwave reactor.

[0087] In a continuous flow fixed bed reactor, a mixed gas with the composition of NO 700ppm, O 25%, balanced carrier gas N2, total gas flow rate of 1000mL / min, and space velocity of 60000-500000mL / (g·h) was introduced into the NO oxidation device heated to 325℃. The outlet gas components NO, NO2 and NO were measured by flue gas analyzer MRU MAG 5. x The NO oxidation conversion rate was used as an indicator. When it reached between 40% and 50%, the reaction was considered stable. The reaction gas passed through a three-way valve and was introduced into the NH3-SCR reaction device. 700 ppm NH3 was introduced through a branch line. SCR catalysis was carried out under microwave heating conditions (the catalyst was heated to 140°C).

[0088] The performance test results of microwave heating catalyst for catalytic reduction of nitric oxide under different space velocities under the same temperature conditions are as follows: Figure 1 shown; through Figure 1 It can be seen that after adding a NO oxidation device in front of the NH3-SCR reaction device, the activity of the catalyst will fluctuate under different space velocity conditions, but it will still be maintained at a relatively high level.

[0089] Example 2

[0090] This example takes the space velocity of 60000 mL / (g·h) in Example 1 as an example, and changes the catalyst heating temperature in the NH3-SCR reaction device, which is recorded as NO oxidation+SCR.

[0091] Comparative Example 1

[0092] The only difference between this comparative example and Example 2 is that no NO oxidation device is provided, which is recorded as SCR.

[0093] The performance test results of catalytic reduction of nitrogen monoxide in Example 2 of the present invention and Comparative Example 1 are as follows: Figure 2 As shown, through Figure 2 It can be seen that after adding a NO oxidation device in front of the NH3-SCR reaction device, the low-temperature activity of the SCR catalyst is significantly improved, the conversion rate of nitrogen monoxide at low temperature of 60°C is increased from 20% to 65.3%, and the active temperature window of the catalyst is also significantly widened.

[0094] Example 3

[0095] Taking the space velocity of 180000 mL / (g·h) in Example 1 as an example, the catalyst heating temperature in the NH3-SCR reaction device is changed, which is recorded as MH.

[0096] Comparative Example 2

[0097] The only difference between this comparative example and Example 3 is that microwave heating is not used, which is recorded as CH.

[0098] The performance test results of catalytic reduction of nitrogen monoxide under different heating conditions of Example 3 of the present invention and Comparative Example 2 are as follows Figure 3 As shown, through Figure 3 It can be seen that after adding a NO oxidation device in front of the NH3-SCR reaction device, microwave heating of the catalyst can significantly enhance the activity of the catalyst under high space velocity and low temperature conditions; at 100°C and 120°C, the NO conversion rate of the catalyst under microwave heating conditions is even nearly 50% higher than that of the catalyst under conventional heating conditions, so it can effectively deal with the nitrogen oxide emission problem during the cold start phase of diesel vehicles.

[0099] Example 4

[0100] The heating temperature of the catalyst (NH3-SCR reaction device) in Example 1 was controlled to 120°C, and the mass space velocity was adjusted to 60000 and 180000 mL / (g·h), respectively recorded as 6×10 4 -MH and 18×10 4 -MH, MH stands for microwave heating, and the stability evaluation is carried out for 10 hours. The test results are as follows Figure 4 As shown, through Figure 4 It can be seen that the catalyst showed excellent stability under microwave heating conditions, and the NO conversion rate increased with time under low space velocity conditions. With the increase of space velocity, the stability of the catalyst decreased slightly, but it still had good stability under high space velocity conditions.

[0101] Example 5

[0102] Take a certain amount of cerium nitrate hexahydrate, calcine it in a muffle furnace to obtain cerium oxide, then mix the cerium oxide with water to prepare a carrier solution; dissolve platinum nitrate in water to obtain a solution containing a platinum source, then add it dropwise to the carrier solution at 6 mL / min (the mass ratio of platinum to cerium oxide is 0.5:100), and after ultrasonication, stir at 90°C and 500 rpm until the solution is evaporated to dryness (time is greater than 6 hours), then dry it in an oven overnight, and finally calcine at 600°C for 3 hours to obtain a Pt / CeO2 catalyst.

[0103] The HZSM-5 molecular sieve was washed, dried and calcined in sequence to complete the pretreatment, and then mixed with water to obtain a carrier solution. The copper sulfate solution was added dropwise to the carrier solution at 4 mL / min (the mass ratio of copper to HZSM-5 molecular sieve was 6:100). After ultrasound, the solution was stirred at 90°C and 500 rpm until it evaporated to dryness (time was greater than 6 hours), and then dried in an oven overnight. Finally, it was calcined at 600°C for 3 hours to obtain the Cu / HZSM-5 molecular sieve denitrification catalyst.

[0104] The Pt / CeO2 catalyst was loaded into a quartz reaction tube, and both ends of the reaction tube were sealed with quartz wool to serve as a NO oxidation device, and the temperature inside the tube was controlled by a tubular resistance furnace; the Cu / HZSM-5 molecular sieve denitrification catalyst was loaded into a quartz tube to serve as an NH3-SCR reaction device, and the temperature inside the tube was controlled by a microwave reactor.

[0105] In a continuous flow fixed bed reactor, a mixed gas with the composition of NO 1000ppm, O 28%, balanced carrier gas N 2, total gas flow rate of 1000mL / min, and space velocity of 60000mL / (g·h) was introduced into the NO oxidation device heated to 300℃. The outlet gas components NO, NO 2 and NO were measured by flue gas analyzer MRU MAG 5. x The NO oxidation conversion rate was used as an indicator. When it reached between 40% and 50%, the reaction was considered stable. The reaction gas passed through a three-way valve and was introduced into the NH3-SCR reaction device. 1000ppm NH3 was introduced through a branch line. SCR catalysis was carried out under microwave heating conditions (the catalyst was heated to 100°C). The test showed that the nitrogen oxide conversion rate was 84.2%.

[0106] Example 6

[0107] Take a certain amount of cerium nitrate hexahydrate, calcine it in a muffle furnace to obtain cerium oxide, then mix the cerium oxide with water to prepare a carrier solution; dissolve platinum nitrate in water to obtain a solution containing a platinum source, then add it dropwise to the carrier solution at 5 mL / min (the mass ratio of platinum to cerium oxide is 0.3:100), and after ultrasonication, stir at 70°C and 500 rpm until the solution is evaporated to dryness (time is greater than 6 hours), then dry it in an oven overnight, and finally calcine at 400°C for 6 hours to obtain a Pt / CeO2 catalyst.

[0108] The HZSM-5 molecular sieve was washed, dried and calcined in sequence to complete the pretreatment, and then mixed with water to obtain a carrier solution. The copper sulfate solution was added dropwise to the carrier solution at 6 mL / min (the mass ratio of copper to HZSM-5 molecular sieve was 1:100). After ultrasound, the solution was stirred at 60°C and 500 rpm until it evaporated to dryness (for more than 6 hours), and then dried in an oven overnight. Finally, it was calcined at 400°C for 6 hours to obtain the Cu / HZSM-5 molecular sieve denitrification catalyst.

[0109] The Pt / CeO2 catalyst was loaded into a quartz reaction tube, and both ends of the reaction tube were sealed with quartz wool to serve as a NO oxidation device, and the temperature inside the tube was controlled by a tubular resistance furnace; the Cu / HZSM-5 molecular sieve denitrification catalyst was loaded into a quartz tube to serve as an NH3-SCR reaction device, and the temperature inside the tube was controlled by a microwave reactor.

[0110] In a continuous flow fixed bed reactor, a mixed gas with the composition of NO 750ppm, O 25%, balanced carrier gas N2, total gas flow rate of 1000mL / min, and space velocity of 60000mL / (g·h) was introduced into the NO oxidation device heated to 350℃. The outlet gas components NO, NO2 and NO were measured by flue gas analyzer MRU MAG 5. x The NO oxidation conversion rate was used as an indicator. When it reached between 40% and 50%, the reaction was considered stable. The reaction gas passed through a three-way valve and was introduced into the NH3-SCR reaction device. 750ppm NH3 was introduced through a branch line. SCR catalysis was carried out under microwave heating conditions (the catalyst was heated to 200°C). The test showed that the nitrogen oxide conversion rate was 72.6%.

[0111] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0112] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for causing a denitration catalyst to undergo a rapid SCR reaction, characterized in that: The device for causing the denitration catalyst to undergo a rapid SCR reaction comprises a NO oxidation device, a switch and an NH3-SCR reaction device arranged in sequence; The NO oxidation device includes a Pt / CeO2 catalyst, and the NH3-SCR reaction device includes a Cu / HZSM-5 molecular sieve denitration catalyst; The device for causing the denitration catalyst to undergo a rapid SCR reaction also includes a first heating device and a second heating device; The first heating device heats the NO oxidation device, and the second heating device heats the NH3-SCR reaction device; The second heating device is a microwave heating device.

2. The device for causing a denitration catalyst to undergo a rapid SCR reaction according to claim 1, characterized in that: The preparation method of the Pt / CeO2 catalyst comprises the following steps: 1) calcining a cerium source to obtain cerium oxide, and mixing the obtained cerium oxide with a solvent to obtain a carrier solution; 2) Mixing a solution containing a platinum source with a carrier solution, drying and calcining to obtain a Pt / CeO2 catalyst.

3. The device for causing a denitration catalyst to undergo a rapid SCR reaction according to claim 2, characterized in that: The cerium source in step 1) includes one or more of cerium nitrate, cerium sulfate and cerium acetate; The platinum source in the solution containing the platinum source in step 2) includes one or more of chloroplatinic acid, platinum nitrate and platinum chloride.

4. The device for causing a denitration catalyst to undergo a rapid SCR reaction according to claim 3, characterized in that: The mass ratio of platinum in the solution containing the platinum source to cerium oxide in the carrier solution in step 2) is 0.1-1.2:100; The mixing temperature in step 2) is 60-90° C. and the mixing time is ≥6 h; The calcination temperature in step 2) is 400-600° C., and the calcination time is 3-6 hours.

5. A device for causing a denitration catalyst to undergo a rapid SCR reaction according to any one of claims 1 to 4, characterized in that: The preparation method of the Cu / HZSM-5 molecular sieve denitration catalyst comprises the following steps: The solution containing the copper source is mixed with the HZSM-5 molecular sieve solution, and then dried and calcined to obtain a Cu / HZSM-5 molecular sieve denitration catalyst.

6. The device for causing a denitration catalyst to undergo a rapid SCR reaction according to claim 5, characterized in that: The copper source in the solution containing the copper source includes one or more of copper nitrate, copper acetate and copper sulfate; The mass ratio of copper in the copper source-containing solution to HZSM-5 molecular sieve in the HZSM-5 molecular sieve solution is 0.5 to 6:100; The mixing temperature is 60-90°C and the mixing time is ≥6h; The calcination temperature is 400-600° C., and the calcination time is 3-6 hours.

7. A method for causing a denitration catalyst to undergo a rapid SCR reaction, characterized in that: The steps include: S1: Turn off the switch of the device that causes the denitration catalyst to undergo a rapid SCR reaction, pass the mixed gas into the NO oxidation device, and heat the mixed gas using the first heating device, so that the mixed gas reacts; S2: After the reaction is stable, the switch is turned on, the mixed gas is passed into the NH3-SCR reaction device, and ammonia is passed into the NH3-SCR reaction device at the same time, and the second heating device is used to heat it to achieve a rapid SCR reaction of the denitration catalyst; The device for causing the denitration catalyst to undergo a rapid SCR reaction is the device described in any one of claims 1 to 6.

8. A method for causing a denitration catalyst to undergo a rapid SCR reaction according to claim 7, characterized in that: In step S1, the mixed gas is a mixed gas of NO, O2 and N2, the volume concentration of NO is 700-2000 ppm, and the volume concentration of O2 is 5-10%; The heating temperature in step S1 is 300-350°C.

9. A method for causing a denitration catalyst to undergo a rapid SCR reaction according to claim 7 or 8, characterized in that: The reaction in step S2 is stabilized such that the NO oxidation conversion rate is controlled at 40-50%; The heating in step S2 is to heat the catalyst to 60-300°C.

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