CN113522286A - Preparation method of composite iron-magnesium oxide SCR denitration catalyst - Google Patents
Preparation method of composite iron-magnesium oxide SCR denitration catalyst Download PDFInfo
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Abstract
The invention discloses a preparation method of a composite iron-magnesium oxide SCR denitration catalyst, and belongs to the technical field of environmental atmospheric pollutant treatment and catalysis. The preparation method comprises the following steps: 1) mixing iron (FeSO)4·7H2O), magnesium (Mg (NO)3)2·6H2O) preparing a mixed solution according to a ratio, fully stirring, and titrating by using a precipitator ammonia water until titration is complete; 2) filtering the suspension and repeatedly washing and filtering the precipitateFully dipping by adopting a sodium carbonate solution after the solution is neutral; 3) carrying out heat treatment on the impregnated precipitate by adopting proper microwave parameters, repeatedly washing the heat-treated precipitate by deionized water to be neutral, and drying; 4) and calcining the obtained dry precipitate, crushing, grinding and screening to obtain the catalyst. The iron-magnesium composite catalyst adopted by the invention has wide sources, is easy to obtain and has low price; and the catalyst has excellent denitration activity, no secondary pollution, easy treatment of the waste catalyst and good industrial application prospect.
Description
Technical Field
The invention belongs to the technical field of environmental atmospheric pollutant treatment and catalysis. In particular to a preparation method of a composite iron-magnesium oxide SCR denitration catalyst.
Background
In China, the energy distribution structure is not uniform, and the coal resources account for about 75% of primary energy in China. The energy structure mainly using coal determines that the thermal power plant constructed at present stage of China mainly uses a coal-fired mode, and SO discharged by combustion of the thermal power plantx，NOxAnd dust and the likeThe materials are seriously harmful to the environment and human health. NOxNot only seriously damaging the ecological environment, but also bringing great threat to human health. In response to severe emission reduction situation and increasing attention of international society to nitrogen oxides, the emission standard of China clearly stipulates that NO of all newly-built thermal power generating units starts from 1 month and 1 day of 2012xThe discharge amount should not exceed 100mg/Nm3(ii) a Simultaneously, starting from 1 month and 1 day in 2014, NO of all thermal power commissioning unit in key areasxThe discharge amount is not more than 100mg/Nm3The unit put into production before 2003 in non-key areas does not exceed 200mg/Nm3Becoming the most severe standard in the current international standard of nitrogen oxide. In 2015 for 12 months, the state requires a coal-fired power plant to implement ultra-low emission modification; the ultra-low emission means that the emission concentration of the atmospheric pollutants of the coal-fired power generating unit basically meets the emission limit requirement of the gas turbine unit and requires NOxThe discharge concentration is not higher than 50mg/Nm3. Furthermore, SO is also proposed explicitly in the national development program2、NOxReduce 15% of the restrictive index. Therefore, faced with harsh NOxEmission standards and heavy emission reduction pressure are imperative to the innovation of the nitrogen oxide control technology. Selective Catalytic Reduction (SCR) technology (NH) using ammonia as reducing agent3SCR) with a relatively simple device structure, easy maintenance, reliable operation and low secondary pollution, up to over 90% NOxThe removal efficiency is high, so that the denitration technology becomes the most widely commercially applied and technically mature coal-fired flue gas denitration technology at present. In order to effectively control NO of coal-fired power plants in ChinaxThe total emission amount meets the requirements of the current emission standard, and the SCR flue gas denitration technology is necessarily called the preferred NO of the thermal generator set in a period of time in the futurexAnd (4) control technology. The catalyst being NH3At the core of the SCR denitration technology, the quality of the catalyst determines not only the flue gas denitration efficiency and reliability, but also the operating cost of the SCR system. The cost of the catalyst in the SCR system is high and accounts for 15 to 20 percent of the initial investment of the SCR system; the catalyst replacement cost is one of the main components of the system operation cost. Stability, selectivity and catalysis of catalystsThe optimum activation temperature window of the agent directly affects the denitration efficiency. The vanadium-titanium catalyst is widely applied to thermal power generating sets in China by virtue of excellent denitration performance, reliable operability and mature technology. But because of its high cost and the dependence of the core technology on imported and oxidized SO2The catalyst has the defects of strong capability, secondary pollution to the environment and the like, and the long-term development of the vanadium-titanium catalyst is limited to a great extent. At present, the state clearly requires that the vanadium-titanium waste flue gas denitration catalyst is brought into dangerous waste for management, and the restriction requirement is put forward for the application of the vanadium-based catalyst for the first time. Therefore, it is imperative to find efficient and inexpensive non-vanadium based catalysts that can replace commercial vanadium titanium catalysts. The iron-based catalyst has the advantages of wide source, low price, excellent denitration activity, no secondary pollution, easy treatment of waste catalyst and the like, and has potential and tendency of replacing vanadium-titanium catalysts.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the problems, the invention provides a preparation method of a composite iron-magnesium oxide SCR denitration catalyst. The preparation method takes iron with wide sources and low price as a raw material, and prepares the iron-magnesium composite oxide SCR denitration catalyst by means of a coprecipitation microwave pyrolysis method.
The technical scheme is as follows: a preparation method of a composite iron-magnesium oxide SCR denitration catalyst comprises the following steps: taking FeSO4·7H2O and Mg (NO)3)2·6H2Adding deionized water to dissolve O, and continuously stirring until the O is fully dissolved; titrating the solution to a pH value of 9-10 by taking ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the precipitate with sodium carbonate solution for 2-5 times, each time for 0.5-2.5h, placing the soaked precipitate in a microwave reactor for heat treatment, repeatedly washing the catalyst precursor prepared by heat treatment with distilled water until the precursor is neutral, drying, calcining at 400 ℃ in a muffle furnace in air atmosphere for 5h, cooling to room temperature, crushing, grinding and screening to obtain the catalyst.
Further, the FeSO4·7H2O and Mg (NO)3)2·6H2Of substances of OThe amount ratio is 9-5: 1-5.
Further, the FeSO4·7H2O and Mg (NO)3)2·6H2The mass ratio of O is 8: 2.
Furthermore, the frequency of the microwave in the heat treatment is 2000-3000MHz, the power of the microwave is 500-1000W, and the microwave time is 15-60 minutes, wherein the microwave lasts for 8s and stops for 14s, and a 22s cycle is formed.
Further, the frequency of the microwave in the heat treatment is 2450MHz, the power of the microwave is 700W, the microwave time is 25 minutes, wherein the microwave lasts for 8s, and stops for 14s, so that 22s of one cycle is formed.
Further, the concentration of the sodium carbonate solution is 1-1.2 mol/L.
Further, the concentration of the ammonia water is 1.5-2 mol/L.
Further, the drying temperature is 105 ℃, and the drying time is not less than 10 h.
Furthermore, the particle size of the catalyst after crushing, grinding and screening is 40-60 meshes.
The beneficial effects are that: the iron-magnesium composite catalyst adopted by the invention takes iron as a raw material, is prepared by a coprecipitation microwave pyrolysis method, and has the advantages of wide raw material source, easy obtainment and low price; and the catalyst has excellent denitration activity, no secondary pollution, easy treatment of the waste catalyst and good industrial application prospect.
Drawings
FIG. 1 is NH3-SCR quartz fixed bed reaction bench schematic.
FIG. 2 is Fe as described in examples 1-51-xMgxOzCatalyst and gamma-Fe as described in comparative example 12O3NH of (2)3-SCR denitration catalytic activity variation diagram.
FIG. 3 is Fe0.8Mg0.2OzThe water-resistant and sulfur-resistant characteristic of the catalyst is shown schematically.
Detailed Description
Example 1
Weighing certain mass of FeSO according to the mass ratio of Fe to Mg of 9:14·7H2O and Mg (NO)3)2·6H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution to a pH value of 9-10 by taking 2mol/L ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate with 1mol/L sodium carbonate solution for 3 times, each time for 1h, placing the obtained filtered precipitate in a microwave reactor, performing heat treatment with 700W microwave power (microwave frequency 2450MHZ) for 25min (wherein the microwave is 8s, and the heating cycle is 22s, and stopping for 14 s), repeatedly washing the prepared catalyst precursor with distilled water until the precursor is neutral, drying the precursor in a blast drying box at 105 ℃ for 10h, and then transferring the precursor to a muffle furnace in air atmosphere at 400 ℃ for calcining for 5h to obtain a catalyst sample. Cooling the catalyst to room temperature, crushing, grinding and screening, selecting 40-60 mesh (particle size of 0.28-0.45 mm) catalyst for later use, and recording the obtained catalyst as Fe0.9Mg0.1Oz。
Example 2
Weighing certain mass of FeSO according to the mass ratio of Fe to Mg of 8:24·7H2O and Mg (NO)3)2·6H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution to a pH value of 9-10 by taking 2mol/L ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate with 1mol/L sodium carbonate solution for 3 times, each time for 1h, placing the obtained filtered precipitate in a microwave reactor, performing heat treatment with 700W microwave power (microwave frequency 2450MHZ) for 25min (wherein the microwave is 8s, and the heating cycle is 22s, and stopping for 14 s), repeatedly washing the prepared catalyst precursor with distilled water until the precursor is neutral, drying the precursor in a blast drying box at 105 ℃ for 10h, and then transferring the precursor to a muffle furnace in air atmosphere at 400 ℃ for calcining for 5h to obtain a catalyst sample. Cooling the catalyst to room temperature, crushing, grinding and screening, selecting 40-60 mesh (particle size of 0.28-0.45 mm) catalyst for later use, and recording the obtained catalyst as Fe0.8Mg0.2Oz。
Example 3
Weighing certain mass of FeSO according to the mass ratio of Fe to Mg of 7:34·7H2O and Mg (NO)3)2·6H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution to a pH value of 9-10 by taking 2mol/L ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate with 1mol/L sodium carbonate solution for 3 times, each time for 1h, placing the obtained filtered precipitate in a microwave reactor, performing heat treatment with 700W microwave power (microwave frequency 2450MHZ) for 25min (wherein the microwave is 8s, and the heating cycle is 22s, and stopping for 14 s), repeatedly washing the prepared catalyst precursor with distilled water until the precursor is neutral, drying the precursor in a blast drying box at 105 ℃ for 10h, and then transferring the precursor to a muffle furnace in air atmosphere at 400 ℃ for calcining for 5h to obtain a catalyst sample. Cooling the catalyst to room temperature, crushing, grinding and screening, selecting 40-60 mesh (particle size of 0.28-0.45 mm) catalyst for later use, and recording the obtained catalyst as Fe0.7Mg0.3Oz。
Example 4
Weighing certain mass of FeSO according to the mass ratio of Fe to Mg of 6:44·7H2O and Mg (NO)3)2·6H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution to a pH value of 9-10 by taking 2mol/L ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate with 1mol/L sodium carbonate solution for 3 times, each time for 1h, placing the obtained filtered precipitate in a microwave reactor, performing heat treatment with 700W microwave power (microwave frequency 2450MHZ) for 25min (wherein the microwave is 8s, and the heating cycle is 22s, and stopping for 14 s), repeatedly washing the prepared catalyst precursor with distilled water until the precursor is neutral, drying the precursor in a blast drying box at 105 ℃ for 10h, and then transferring the precursor to a muffle furnace in air atmosphere at 400 ℃ for calcining for 5h to obtain a catalyst sample. Cooling the catalyst to room temperature, crushing, grinding and screening, selecting 40-60 mesh (particle size of 0.28-0.45 mm) catalyst for later use, and recording the obtained catalyst as Fe0.6Mg0.4Oz。
Example 5
Weighing certain mass of FeSO according to the mass ratio of Fe to Mg of 5:54·7H2O and Mg (NO)3)2·6H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution to a pH value of 9-10 by taking 2mol/L ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate with 1mol/L sodium carbonate solution for 3 times, each time for 1h, placing the obtained filtered precipitate in a microwave reactor, performing heat treatment with 700W microwave power (microwave frequency 2450MHZ) for 25min (wherein the microwave is 8s, and the heating cycle is 22s, and stopping for 14 s), repeatedly washing the prepared catalyst precursor with distilled water until the precursor is neutral, drying the precursor in a blast drying box at 105 ℃ for 10h, and then transferring the precursor to a muffle furnace in air atmosphere at 400 ℃ for calcining for 5h to obtain a catalyst sample. Cooling the catalyst to room temperature, crushing, grinding and screening, selecting 40-60 mesh (particle size of 0.28-0.45 mm) catalyst for later use, and recording the obtained catalyst as Fe0.5Mg0.5Oz。
Example 6
Catalyst NH3The SCR activity test is completed on a quartz fixed bed reaction system test bed which is independently built in a laboratory. As shown in figure 1, the experimental system mainly comprises a simulated flue gas distribution system, a catalyst preheating and reaction system and a flue gas component online acquisition and analysis system. The simulated flue gas is formed by fully mixing standard gas in a gas mixing tank after the standard gas is decompressed by a decompression valve and the flow is controlled by a mass flowmeter. Then the simulated flue gas enters a preheating section and a reaction section in sequence, and the preheating of the catalyst and the NH are completed at the preheating section3-SCR denitration reaction. The preheating section adopts a K-type thermocouple to monitor and simulate the real-time temperature of the flue gas, and is externally connected with a temperature controller to accurately control the temperature of the preheating section. The reaction section adopts a tubular resistance furnace for heating, a K-type thermocouple feeds back the temperature of a catalyst bed layer, and a catalyst sample for reaction is placed on a sand core of the quartz reactor. The online collection and analysis of smoke components are realized by a German MRU MGA5 multi-component smoke analyzer. Before entering the flue gas analyzer, the simulated flue gas passes through a gas washing bottle filled with concentrated phosphoric acid and a drying agent respectively to avoid NH carried in the flue gas3And H2O pair flue gas analysisThe infrared sensor of the instrument is corroded, and the accuracy of an experimental result is further influenced.
Typical SCR reaction conditions are referenced to actual plant operating conditions, with inlet simulated flue gas standard set to 0.1 vol.% NO +0.1 vol.% NH3+3.5vol.％O2，N2Is balance gas; 0.1 vol.% NO +0.1 vol.% NH in antitoxic experiments3+3.5vol.％O2+(0.02-0.08)vol.％SO2+(1-10)vol.％O2. The experimental temperature range is 100-400 ℃, the catalyst dosage is 4mL, the flue Gas flow is 2L/min, and the air velocity ratio (GHSV) is 30000h-1. Before the experiment is started, in order to prevent the simulation flue gas from adsorbing on the surface of the catalyst unevenly to interfere the accuracy of the experiment, the simulation flue gas is used for purging the catalyst for more than 2 hours; and (3) after the stable operation is carried out for 50min at every 25 ℃ as an experimental temperature point, recording data after the contents of all components in the inlet flue gas and the outlet flue gas are stable. Definition of NOxThe conversion equation is as follows:
wherein eta is NOxConversion, CNOx(inlet) NO at the inletxConcentration,. mu.L/L; CNOx(outlet) is NO at the outlet after the reactionxConcentration,. mu.L/L. NOxIn concentrations of NO and NO2Sum of concentrations.
Table 1 denitration efficiency of different iron-magnesium composite oxide catalysts obtained in examples 1 to 5 at different temperatures
As shown in FIG. 2, in the simulation experiment, Fe0.8Mg0.2Oz catalyst shows the most excellent denitration performance, and the denitration efficiency of the catalyst is changed along with temperatureThe temperature rises gradually, the maximum denitration efficiency can reach 99.1% at 325 ℃, the activity temperature window is 250-350 ℃, and the denitration efficiency of the catalyst is reduced slowly along with the further rise of the temperature. Fe in comparison with other groups of catalysts0.8Mg0.2The Oz catalyst has the widest denitration temperature window and the maximum denitration efficiency.
In the absence of SO2And H2In the presence of O, Fe0.8Mg0.2OzThe catalyst can keep the denitration efficiency of about 92 percent to stably operate; after 1h, 0.03 vol.% SO was introduced into the reaction flue gas2、8vol.％H2O and 0.03 vol.% SO2+8vol.％H2O, at 2h, Fe0.8Mg0.2OzThe denitration efficiency of the catalyst is respectively reduced to about 84.16%, 84.42% and 78.92%; after ten hours of operation, Fe0.8Mg0.2OzThe denitration efficiency of the catalyst continues to decrease in a small amount and is stabilized at about 71%, 89%, 71%, respectively. When SO is stopped2And H2After O, Fe under three conditions can be seen0.8Mg0.2OzThe activity of the catalyst can still be raised back to a higher level as shown in figure 3.
TABLE 2 Fe0.8Mg0.2OzWater and sulfur resistance performance data of catalyst
Example 7
Weighing certain mass of FeSO according to the mass ratio of Fe to Mg of 8:24·7H2O and Mg (NO)3)2·6H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution by using 1.5mol/L ammonia water as a precipitator until the pH value is 9-10; after titration, the suspension is filteredRepeatedly washing the mixture to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate for 2 times with 1.1mol/L sodium carbonate solution, each time for 2.5h, placing the obtained filtered precipitate in a microwave reactor, performing heat treatment with 500W microwave power (microwave frequency 2000MHZ) for 60min (wherein microwave is 8s, and is stopped for 14s, and 22s heating cycle is formed), repeatedly washing the prepared catalyst precursor with distilled water until the precursor is neutral, drying in a forced air drying box at 105 ℃ for 10h, and then transferring to a muffle furnace at 400 ℃ in air atmosphere to calcine for 5h to obtain a catalyst sample. And cooling the catalyst to room temperature, crushing, grinding and screening, and selecting the catalyst with the particle size of 0.28-0.45 mm of 40-60 meshes for later use to obtain the catalyst.
Example 8
Weighing certain mass of FeSO according to the mass ratio of Fe to Mg of 8:24·7H2O and Mg (NO)3)2·6H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution by using 1.8mol/L ammonia water as a precipitator until the pH value is 9-10; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate for 5 times with 1.2mol/L sodium carbonate solution, each time for 0.5h, placing the obtained filtered precipitate in a microwave reactor, performing heat treatment for 15min at 1000W microwave power (microwave frequency of 3000MHz) (wherein microwave is 8s, and is stopped for 14s, and 22s heating cycle is formed), repeatedly washing the prepared catalyst precursor with distilled water until the precursor is neutral, drying in a forced air drying box at 105 ℃ for 10h, and then transferring to a muffle furnace at 400 ℃ in air atmosphere to calcine for 5h to obtain a catalyst sample. And cooling the catalyst to room temperature, crushing, grinding and screening, and selecting the catalyst with the particle size of 0.28-0.45 mm of 40-60 meshes for later use to obtain the catalyst.
Comparative example 1
Weighing certain mass of FeSO4·7H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution to a pH value of 9-10 by taking 2mol/L ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate with 1mol/L sodium carbonate solution for 3 times, each for 1 hr to obtain filtered precipitateAnd (3) putting the precipitate into a microwave reactor, carrying out heat treatment for 25min (wherein the microwave is 8s, the microwave is stopped for 14s, and a heating cycle is formed for 22 s), repeatedly washing the prepared catalyst precursor with distilled water until the precursor is neutral, drying the precursor in a blast drying box at 105 ℃ for 10h, and then transferring the precursor to a muffle furnace in an air atmosphere at 400 ℃ to calcine the precursor for 5h to obtain a catalyst sample. The catalyst is cooled to room temperature, crushed, ground and sieved, and the catalyst with the grain size of 40-60 meshes (0.28-0.45 mm) is selected for standby. Obtaining the catalyst gamma-Fe2O3。
In a simulation test, the gamma-Fe of comparative example 1 was found2O3The denitration efficiency of the catalyst gradually rises along with the rise of the temperature, reaches the maximum denitration efficiency at 300 ℃, is only 89.05 percent, and then shows a rapid descending trend along with the further rise of the temperature; fe in example 30.8Mg0.2OzThe maximum denitration efficiency of the catalyst can reach 99.08%, and Fe is obtained at the same temperature from 250 DEG C0.8Mg0.2OzThe denitration efficiency of the catalyst is higher than that of gamma-Fe2O3The catalyst is higher by about 20-30 percentage points, and Fe is generated when the temperature reaches 350 DEG C0.8Mg0.2OzThe denitration efficiency of the catalyst is reduced slowly and is obviously superior to gamma-Fe2O3A catalyst.
TABLE 3. gamma. -Fe2O3Catalyst and Fe0.8Mg0.2OzComparison of catalyst denitration Performance
| Temperature of | γ-Fe2O3 | Fe0.8Mg0.2Oz |
| 100 | 10.98％ | 8.66％ |
| 125 | 11.45％ | 11.16％ |
| 150 | 13.19％ | 15.11％ |
| 175 | 18.96％ | 21.66％ |
| 200 | 32.92％ | 47.64％ |
| 225 | 50.91％ | 73.72％ |
| 250 | 67.56％ | 91.07％ |
| 275 | 81.88％ | 96.71％ |
| 300 | 89.05％ | 98.56％ |
| 325 | 84.79％ | 99.08％ |
| 350 | 63.95％ | 94.35％ |
| 375 | 37.40％ | 64.48％ |
| 400 | 5.43％ | 40.89％ |
TABLE 4. gamma. -Fe2O3Catalyst and Fe0.8Mg0.2OzSpecific surface area, pore volume and average pore diameter of catalyst
| samples | SBET/m2·g-1 | Pore volume/cm3·g-1 | Average Pore diameter/nm |
| γ-Fe2O3 | 27.93 | 0.15 | 21.21 |
| Fe0.8Mg0.2Oz | 44.00 | 0.19 | 16.83 |
For gamma-Fe2O3Catalyst and Fe0.8Mg0.2OzThe specific surface area, the pore volume and the average pore diameter of the catalyst are detected and analyzed, and Fe is found0.8Mg0.2OzThe specific surface area and the pore volume of the catalyst are obviously superior to those of gamma-Fe2O3Catalyst with average pore diameter smaller than gamma-Fe2O3The catalyst is beneficial to the adsorption of reaction gas on the surface of the catalyst, so that the denitration efficiency is improved.
Comparative example 2
Weighing certain mass of FeSO according to the mass ratio of Fe to Mg of 8:24·7H2O and Mg (NO)3)2·6H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution to a pH value of 9-10 by taking 2mol/L ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate for 3 times by using 1mol/L sodium carbonate solution, placing the obtained filtered precipitate in a microwave reactor, performing heat treatment for 25min by using 700W microwave power (microwave frequency of 2450MHz) (wherein the microwave is 8s, and the heating cycle is formed by stopping for 14s, and forming 22 s), repeatedly washing the prepared catalyst precursor by using distilled water until the precursor is neutral, drying the precursor in a blast drying box at 105 ℃ for 10h, and then transferring the dried precursor to a muffle furnace at 350 ℃ in air atmosphere to calcine for 5h to obtain a catalyst sample. Cooling the catalyst to room temperature, crushing, grinding and screening, selecting 40-60 mesh (particle size of 0.28-0.45 mm) catalyst for later use, and recording the obtained catalyst as Fe0.8Mg0.2Oz(350)。
Comparative example 3
Weighing certain mass of FeSO according to the mass ratio of Fe to Mg of 8:24·7H2O and Mg (NO)3)2·6H2And O, adding deionized water to dissolve and fix the volume to 250mL, and continuously stirring for 1h until the solution is fully dissolved. Titrating the solution to a pH value of 9-10 by taking 2mol/L ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the filtered precipitate for 3 times by using 1mol/L sodium carbonate solution, placing the obtained filtered precipitate in a microwave reactor, performing heat treatment for 25min by using 700W microwave power (microwave frequency of 2450MHz) (wherein the microwave is 8s, and the microwave is stopped for 14s to form 22s of heating cycle), repeatedly washing the prepared catalyst precursor by using distilled water until the precursor is neutral, drying the precursor in a blast drying box at 105 ℃ for 10h, and then transferring the dried precursor to a muffle furnace to perform calcination at 450 ℃ for 5h to obtain a catalyst sample. Cooling the catalyst to room temperature, crushing, grinding and screening, selecting 40-60 mesh (particle size of 0.28-0.45 mm) catalyst for later use, and recording the obtained catalyst as Fe0.8Mg0.2Oz(450)。
Fe in example 30.8Mg0.2OzCatalyst, Fe in comparative example 20.8Mg0.2Oz(350) Catalyst and Fe in comparative example 30.8Mg0.2Oz(450) The denitration efficiency of the catalyst at different temperatures is shown in the following table, Fe in example 30.8Mg0.2OzThe denitration performance of the catalyst is obviously superior to that of the other two groups.
TABLE 5 Fe0.8Mg0.2OzCatalyst and Fe0.8Mg0.2Oz(350) Denitration efficiency comparison of catalyst
| Temperature of | 100 | 150 | 200 | 250 | 300 | 350 | 400 |
| Fe0.8Mg0.2Oz | 8.66％ | 15.11％ | 47.64％ | 91.07％ | 98.56％ | 94.35％ | 40.89％ |
| Fe0.8Mg0.2Oz(350) | 5.68％ | 7.38％ | 21.44％ | 55.00％ | 86.25％ | 86.94 | 21.86％ |
| Fe0.8Mg0.2Oz(450) | 5.22％ | 6.50％ | 19.49％ | 53.54％ | 95.97％ | 70.23％ | 2.16％ |
Claims (9)
1. A preparation method of a composite iron-magnesium oxide SCR denitration catalyst is characterized by comprising the following steps: taking FeSO4·7H2O and Mg (NO)3)2·6H2Adding deionized water to dissolve O, and continuously stirring until the O is fully dissolved; titrating the solution to a pH value of 9-10 by taking ammonia water as a precipitator; filtering the turbid liquid after titration, and repeatedly washing the turbid liquid to be neutral by using deionized water to remove impurity ions; soaking the precipitate with sodium carbonate solution for 2-5 times, each for 0.5-2.5 hr, heat treating the soaked precipitate in a microwave reactor, washing the heat treated catalyst precursor with distilled water repeatedly until it is neutral, drying, and transferring to muffle furnace under 400 deg.CoAnd C, calcining for 5 hours, cooling to room temperature, and crushing, grinding and screening to obtain the catalyst.
2. The preparation method of the composite iron-magnesium oxide SCR denitration catalyst according to claim 1, characterized by comprising the following steps: the FeSO4·7H2O and Mg (NO)3)2·6H2The mass ratio of O is 9-5: 1-5.
3. The preparation method of the composite iron-magnesium oxide SCR denitration catalyst according to claim 2, characterized by comprising the following steps: the FeSO4·7H2O and Mg (NO)3)2·6H2The mass ratio of O is 8: 2.
4. The preparation method of the composite iron-magnesium oxide SCR denitration catalyst according to claim 1, characterized by comprising the following steps: the frequency of the microwave in the heat treatment is 2000-3000MHz, the power of the microwave is 500-1000W, and the microwave time is 15-60 minutes, wherein the microwave lasts for 8s, and stops for 14s, thereby forming a 22s cycle.
5. The preparation method of the composite iron-magnesium oxide SCR denitration catalyst according to claim 4, characterized by comprising the following steps: the frequency of the microwave in the heat treatment is 2450MHz, the power of the microwave is 700W, the microwave time is 25 minutes, wherein the microwave is stopped for 14s after 8s, and a cycle of 22s is formed.
6. The preparation method of the composite iron-magnesium oxide SCR denitration catalyst according to claim 1, characterized by comprising the following steps: the concentration of the sodium carbonate solution is 1-1.2 mol/L.
7. The preparation method of the composite iron-magnesium oxide SCR denitration catalyst according to claim 1, characterized by comprising the following steps: the concentration of the ammonia water is 1.5-2 mol/L.
8. The preparation method of the composite iron-magnesium oxide SCR denitration catalyst according to claim 1, characterized by comprising the following steps: the drying temperature is 105 DEG CoAnd C, drying for not less than 10 h.
9. The preparation method of the composite iron-magnesium oxide SCR denitration catalyst according to claim 1, characterized by comprising the following steps: the particle size of the catalyst after crushing, grinding and screening is 40-60 meshes.
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| CN102658155A (en) * | 2012-04-28 | 2012-09-12 | 山东大学 | Preparation method of supported type denitration catalyst |
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| CN102658155A (en) * | 2012-04-28 | 2012-09-12 | 山东大学 | Preparation method of supported type denitration catalyst |
| WO2017049804A1 (en) * | 2015-09-23 | 2017-03-30 | 上海交通大学 | Catalyst capable of catalytically removing environmental pollutants at low temperature and preparation method thereof |
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