CN108855052B

CN108855052B - Efficient multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst and preparation method thereof

Info

Publication number: CN108855052B
Application number: CN201810657340.XA
Authority: CN
Inventors: 姚小江; 陈丽; 杨复沫; 曹俊; 罗琼
Original assignee: Chongqing Institute of Green and Intelligent Technology of CAS
Current assignee: Chongqing Institute of Green and Intelligent Technology of CAS
Priority date: 2018-06-25
Filing date: 2018-06-25
Publication date: 2021-02-26
Anticipated expiration: 2038-06-25
Also published as: CN108855052A

Abstract

The invention provides a high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst and a preparation method thereof, wherein the preparation method comprises the following steps: 1) dissolving a compound containing Ce, Mn, Ti and Sn elements in a proper amount of water to prepare a mixed solution for later use; 2) adding the mixed solution prepared in the step 1) into excessive concentrated ammonia water, and reacting to prepare a suspension; 3) carrying out solid-liquid separation on the suspension prepared in the step 2), and carrying out post-treatment on the obtained solid to obtain the finished product of the high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst. Catalyst pair prepared by the invention generates N₂The inhibition effect of O is obvious, the denitration performance is obviously improved, the needed raw materials are cheap and easy to obtain, the preparation method is simple, the flow is clear, and the operation is safe.

Description

Efficient multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst and preparation method thereof

Technical Field

The invention relates to the field of air pollution control, in particular to an efficient multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst and a preparation method thereof.

Background

Nitrogen Oxides (NO) from stationary sources (e.g., coal-fired power plants) and mobile sources (e.g., automobile exhaust) emissions_x) As one of the main pollutants of the atmosphere, mainly NO and NO are included₂It can cause environmental problems such as acid rain, photochemical smog, ozone layer damage, water eutrophication, haze and the like, and has certain influence on climate change and human health. With the increase of the total amount of nitrogen oxides discharged, the emission limit of nitrogen oxides is becoming stricter and stricter, which is published by the environmental protection department of 2011 in thermal power plant atmosphereThe emission standard of nitrogen oxides of a coal-fired power plant is regulated to be 100mg/m by the emission standard of pollutants (GB13223-2011)³In the ultralow emission standard established in 2015, the emission limit of nitrogen oxides of the coal-fired power plant in China reaches the historical new emission limit of 50mg/m³. Ammonia-Selective Catalytic Reduction of NO_x by NH₃NH for short₃SCR) is the most mature and widely applied flue gas denitration technology with highest efficiency at present, and becomes the first choice technology for flue gas denitration in China.

The current commercial application is mature V₂O₅-WO₃/TiO₂The denitration catalyst of the system meets the high-temperature operation condition (300-400 ℃), the denitration device is arranged in front of the desulfuration and dust removal device, and the catalyst is exposed to the complex components (alkali metal, alkaline earth metal, phosphorus, arsenic, heavy metal and high SO) of the flue gas for a long time₂) In the operating environment of (2), the catalyst is blocked or poisoned, and the catalyst is inactivated, so that the denitration efficiency and the denitration cost are influenced. If denitration is carried out after dust removal and desulfurization, the flue gas temperature is usually low, the high-temperature operation temperature is difficult to meet, and secondary heating is needed to increase energy consumption. In addition, the catalyst of the system has the characteristic of easily generating a byproduct N at high temperature₂O, containing a biologically toxic active component V₂O₅(easy sublimation or shedding under high-temperature operation condition, potential harm to ecological environment and human health) and the like, and research and development of high-efficiency low-temperature (150-300 ℃) non-vanadium-based NH₃The SCR catalyst can solve the technical bottleneck and self limitation of the existing high-temperature catalyst, and has great significance for the denitration industry.

CeO₂-MnO_xThe series of catalysts are low-temperature denitration catalysts which are researched more and have better effects at present. However, the catalyst of the system is NH at low temperature₃A large amount of by-product N during operation of the SCR system₂The poor performance of O generation, water resistance and sulfur resistance is a main reason for hindering the industrial application of the series of catalysts.

N₂O is a key byproduct in the low-temperature denitration process and is also an important atmospheric pollutant. NH (NH)₃The purpose of SCR denitration is in the catalystBy the action of NH₃Adding NO as toxic gas to reducing agent_xReducing to nontoxic and harmless N₂. If a large amount of N is produced during the reaction₂O, indicating that the catalyst performance is not excellent. Recent research results show how to effectively inhibit N₂The large amount of generated O is a bottleneck problem faced by low-temperature denitration.

Thus, by the use of CeO₂-MnO_xThe catalyst is modified to improve the catalytic activity, water resistance and sulfur resistance and reduce the N₂The O generation amount has important practical significance.

Disclosure of Invention

In view of the above disadvantages of the prior art, the present invention aims to provide a high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst, which is used to solve the problems of the prior art, such as difficulty in operation in a low-temperature environment, easy generation of toxic and harmful byproducts, easy environmental pollution, and poor denitration performance.

In order to achieve the above and other related objects, a first aspect of the present invention provides a method for preparing a high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst, comprising the steps of:

1) dissolving a compound containing Ce, Mn, Ti and Sn elements in a proper amount of water to prepare a mixed solution for later use;

2) adding the mixed solution prepared in the step 1) into excessive concentrated ammonia water, and reacting to prepare a suspension;

3) carrying out solid-liquid separation on the suspension prepared in the step 2), and carrying out post-treatment on the obtained solid to obtain the finished product of the high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst.

In some embodiments of the present invention, in the step 1), the water is selected from at least one of ultrapure water, deionized water and distilled water.

In some embodiments of the invention, in step 1), Ce: Mn: Ti: Sn ═ 6-9: 2:1:1 by moles.

In some embodiments of the invention, in the step 1), the compound containing Ce, Mn, Ti, Sn elements is selected from Ce (NO)₃)₃、Mn(NO₃)₂、TiCl₄、SnCl₄。

In some embodiments of the invention, in step 1), the Ce (NO)₃)₃Can be Ce (NO)₃)₃Solid, also can be Ce (NO)₃)₃Preparing the obtained solution or Ce (NO)₃)₃And a hydrate of (5), specifically may be Ce (NO)₃)₃·6H₂O。

In some embodiments of the invention, the Mn (NO) in step 1) is₃)₂Can be Mn (NO)₃)₂Solid, also Mn (NO)₃)₂Preparing the obtained solution or Mn (NO)₃)₂The amount of Mn (NO) may be specifically 50% (mass fraction)₃)₂An aqueous solution.

In some embodiments of the invention, the SnCl in the step 1) is₄May be SnCl₄Solid, also can be SnCl₄Preparing the obtained solution or SnCl₄The hydrate of (2) may be specifically SnCl₄·5H₂O。

In some embodiments of the invention, said TiCl in said step 1)₄Can be TiCl₄Preparing the obtained solution or TiCl₄And the like, specifically TiCl₄An aqueous solution.

In some embodiments of the invention, in said step 1), TiCl is reacted with₄Dropwise adding into ultrapure water containing 1-10% (volume ratio) hydrochloric acid under ice water bath condition, magnetically stirring, and preparing into TiCl with concentration of 0.05-0.50mol/L₄And (3) solution.

In some embodiments of the invention, in step 1), SnCl is added₄·5H₂Dissolving O in ultrapure water containing 1-10% (volume ratio) hydrochloric acid to prepare 0.20-2.00mol/L SnCl₄And (3) solution.

In some embodiments of the invention, in step 1), Ce (NO) is added₃)₃、Mn(NO₃)₂、TiCl₄、SnCl₄Dissolved in a proper amount of water to prepare a mixed solution with the volume of 100-200 mL.

In some embodiments of the present invention, in step 1), Mn (NO) is first added₃)₂Preparing into 50% water solution, and adding into the mixed solution.

In some embodiments of the invention, in the step 2), the mixed solution prepared in the step 1) is slowly added into excessive concentrated ammonia water dropwise, the reaction is carried out until the mixed solution is completely precipitated, the obtained suspension is continuously stirred for 2-3 hours (the uniform mixing is favorable for forming a uniform solid solution structure, so that the interaction among the components is enhanced), and the obtained suspension is aged for more than 12 hours (the crystal nucleus growth is promoted, so that a perfect solid solution crystal structure is formed).

In some embodiments of the present invention, the aging time in step 2) is preferably 12 to 24 hours.

In some embodiments of the present invention, in step 2), the pH of the suspension obtained after mixing the mixed solution with concentrated ammonia water is greater than or equal to 10, and preferably, the pH is10 to 12.

In some embodiments of the invention, in the step 2), the mass fraction of the concentrated ammonia water is 25%.

In some embodiments of the present invention, in step 3), the post-treatment specifically includes washing, drying, and roasting.

In some embodiments of the invention, in step 3), the resulting filter cake is washed to a wash pH of 7, with no detectable chloride ions using silver nitrate solution.

In some embodiments of the invention, the drying temperature in step 3) is 60-120 ℃.

In some embodiments of the present invention, in the step 3), the drying time is 6 to 24 hours.

In some embodiments of the present invention, in the step 3), the temperature for calcination is 350-650 ℃.

In some embodiments of the present invention, in the step 3), the temperature rising rate during the roasting is 1-2 ℃/min.

The invention provides a high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst, which contains Ce, Mn, Ti and Sn elements.

In some embodiments of the invention, the molar ratio of Ce: Mn: Ti: Sn ═ 6-9: 2:1: 1.

In some embodiments of the invention, the following raw materials are included: ce (NO)₃)₃、Mn(NO₃)₂、TiCl₄、SnCl₄。

The third aspect of the invention provides the efficient multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst prepared by the method.

The fourth aspect of the invention provides the high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst in NH₃-use in an SCR reaction.

The fifth aspect of the invention provides an application of the high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst in low-temperature denitration of a coal-fired power plant.

The efficient multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst and the preparation method thereof have the following beneficial effects: catalyst pair prepared by the invention generates N₂The inhibition effect of O is obvious, the denitration performance is obviously improved, the needed raw materials are cheap and easy to obtain, the preparation method is simple, the flow is clear, and the operation is safe.

Drawings

FIG. 1 shows CeO₂-MnO_x-TiO₂-SnO₂、CeO₂-MnO_x-TiO₂、CeO₂-MnO_x-SnO₂、CeO₂-MnO_xXRD pattern of catalyst.

FIG. 2 shows CeO₂-MnO_x-TiO₂-SnO₂、CeO₂-MnO_x-TiO₂、CeO₂-MnO_x-SnO₂、CeO₂-MnO_xH of catalyst₂-TPR graph.

FIG. 3 shows CeO₂-MnO_x-TiO₂-SnO₂、CeO₂-MnO_x-TiO₂、CeO₂-MnO_x-SnO₂、CeO₂-MnO_xNH of catalyst₃-TPD profile.

FIG. 4 shows CeO₂-MnO_x-TiO₂-SnO₂、CeO₂-MnO_x-TiO₂、CeO₂-MnO_x-SnO₂、CeO₂-MnO_xNO of catalyst_xGraphs (a) and N of conversion₂Graph (b) of the generated concentration of O.

FIG. 5 shows CeO₂-MnO_x-TiO₂-SnO₂、CeO₂-MnO_x-TiO₂、CeO₂-MnO_x-SnO₂、CeO₂-MnO_xThe water-resistant and sulfur-resistant performance of the catalyst.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It should be understood that the processing equipment or devices not specifically mentioned in the following examples are conventional in the art; all pressure values and ranges refer to absolute pressures.

Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.

Example 1

CeO₂-MnO_x-TiO₂-SnO₂Preparation of denitration catalyst (abbreviated as Ce-Mn-Ti-Sn catalyst)

14mL of TiCl₄Dropwise adding the mixture into ultrapure water containing 2mL of concentrated hydrochloric acid under the condition of ice-water bath, and uniformly stirring the mixture by magnetic force to prepare TiCl with the concentration of 0.5mol/L₄A solution; SnCl₄·5H₂Dissolving O in ultrapure water containing 2mL concentrated hydrochloric acid to prepare 2mol/L SnCl₄A solution; 19.5017g of Ce (NO) are accurately weighed₃)₃·6H₂O、4.0185g Mn(NO₃)₂The solution (50% by mass) is mixed with the above TiCl accurately measured₄Solution (11.2mL) and SnCl₄The solution (28.1mL) is transferred into a beaker filled with ultrapure water (the volume of the solution is kept at 150mL) to be dissolved and mixed uniformly, and after the solution is stirred vigorously for 2 hours, the obtained mixed solution is slowly dripped into excessive concentrated ammonia water (25 percent) to ensure that the pH value is 10; continuously stirring the obtained suspension for 3h, aging for 24h, then carrying out suction filtration and water washing for several times until the pH value of the washing liquid is neutral, detecting that no precipitate appears in the washing liquid by using a silver nitrate solution, drying the obtained filter cake in a drying oven at 110 ℃ for 12h, naturally cooling to room temperature, taking out, grinding for 30min by using an agate mortar, placing in a muffle furnace, heating from the room temperature to 500 ℃ at the speed of 2 ℃/min under the flowing air atmosphere of 100mL/min, roasting for 5h, naturally cooling to room temperature, taking out, grinding for 30min in the agate mortar, and obtaining CeO₂、MnO_x、TiO₂、SnO₂CeO in a molar ratio of 8:2:1:1₂-MnO_x-TiO₂-SnO₂The catalyst is abbreviated as Ce-Mn-Ti-Sn catalyst. Its XRD, H₂-TPR、NH₃TPD and NH₃The results of the SCR reaction are shown in FIGS. 1 to 5 and tables 1 to 2.

Comparative example 1

CeO₂-MnO_x-TiO₂Preparation of denitration catalyst (abbreviated as Ce-Mn-Ti catalyst)

14mL of TiCl₄Dropwise adding the mixture into ultrapure water containing 2mL of concentrated hydrochloric acid under the condition of ice-water bath, and uniformly stirring the mixture by magnetic force to prepare TiCl with the concentration of 0.5mol/L₄A solution; 21.3042g of Ce (NO) are accurately weighed₃)₃·6H₂O、4.3899g Mn(NO₃)₂The solution (50% by mass) is mixed with the above TiCl accurately measured₄The solution (12.3mL) is transferred into a beaker filled with ultrapure water (the volume of the solution is kept at 150mL) to be dissolved and mixed uniformly, and after the solution is stirred vigorously for 2 hours, the obtained mixed solution is slowly dripped into excessive concentrated ammonia water (25 percent) to ensure that the pH value is 10; continuously stirring the obtained suspension for 3h, aging for 24h, then carrying out suction filtration and water washing for several times until the pH value of the washing liquid is neutral, detecting that no precipitate appears in the washing liquid by using a silver nitrate solution, drying the obtained filter cake in a drying oven at 110 ℃ for 12h, naturally cooling to room temperature, taking out, grinding for 30min by using an agate mortar, placing the mixture in a muffle furnace, heating from the room temperature to 500 ℃ at the speed of 2 ℃/min under the flowing air atmosphere of 100mL/min, roasting for 5h, naturally cooling to the room temperature, taking out, grinding for 30min in the agate mortar, and obtaining CeO₂、MnO_x、TiO₂CeO in a molar ratio of 8:2:1₂-MnO_x-TiO₂The catalyst is abbreviated as Ce-Mn-Ti catalyst. Its XRD, H₂-TPR、NH₃TPD and NH₃The results of the SCR reaction are shown in FIGS. 1 to 5 and tables 1 to 2.

Comparative example 2

CeO₂-MnO_x-SnO₂Preparation of denitration catalyst (abbreviated as Ce-Mn-Sn catalyst)

SnCl₄·5H₂Dissolving O in ultrapure water containing 2mL concentrated hydrochloric acid to prepare 2mol/L SnCl₄The solution was accurately weighed 20.4172g of Ce (NO)₃)₃·6H₂O、4.2071g Mn(NO₃)₂The solution (mass percent is 50 percent) is mixed with the SnCl which is accurately measured₄The solution (29.4mL) is transferred into a beaker filled with ultrapure water (the volume of the solution is kept at 150mL) to be dissolved and mixed uniformly, and after the solution is stirred vigorously for 2 hours, the obtained mixed solution is slowly dripped into excessive concentrated ammonia water (25 percent) to ensure that the pH value is 10; continuously stirring the obtained suspension for 3h, aging for 24h, performing suction filtration and water washing for several times until the pH value of the washing liquid is neutral, detecting that no precipitate appears in the washing liquid by using a silver nitrate solution, drying the obtained filter cake in a drying oven at 110 ℃ for 12h, naturally cooling to room temperature, taking out, grinding for 30min by using an agate mortar, placing in a muffle furnace, and performing air flow at a flow rate of 100mL/minHeating to 500 deg.C at a rate of 2 deg.C/min, calcining for 5 hr, naturally cooling to room temperature, taking out, grinding in agate mortar for 30min to obtain CeO₂、MnO_x、SnO₂CeO in a molar ratio of 8:2:1₂-MnO_x-SnO₂The catalyst is abbreviated as Ce-Mn-Sn catalyst. Its XRD, H₂-TPR、NH₃TPD and NH₃The results of the SCR reaction are shown in FIGS. 1 to 5 and tables 1 to 2.

Comparative example 3CeO₂-MnO_xPreparation of denitration catalyst (abbreviated as Ce-Mn catalyst)

22.4015g Ce (NO) was weighed out accurately₃)₃·6H₂O and 4.6160g Mn (NO)₃)₂The solution (the mass fraction is 50 percent) is put into a beaker filled with ultrapure water (the volume of the solution is kept at 150mL) to be dissolved and mixed uniformly, the mixed solution is stirred vigorously for 2 hours, and then the obtained mixed solution is slowly dripped into excessive concentrated ammonia water (25 percent) to ensure that the pH value is 10; continuously stirring the obtained suspension for 3h, aging for 24h, then carrying out suction filtration and water washing for several times until the pH value of the washing liquid is neutral, detecting that no precipitate appears in the washing liquid by using a silver nitrate solution, drying the obtained filter cake in a drying oven at 110 ℃ for 12h, naturally cooling to room temperature, taking out, grinding for 30min by using an agate mortar, placing the mixture in a muffle furnace, heating from the room temperature to 500 ℃ at the speed of 2 ℃/min under the flowing air atmosphere of 100mL/min, roasting for 5h, naturally cooling to the room temperature, taking out, grinding for 30min in the agate mortar, and obtaining CeO₂、MnO_xCeO in a molar ratio of 8:2₂-MnO_xThe catalyst is abbreviated as Ce-Mn catalyst. Its XRD, H₂-TPR、NH₃TPD and NH₃The results of the SCR reaction are shown in FIGS. 1 to 5 and tables 1 to 2.

FIG. 1 shows XRD results of Ce-Mn-Ti-Sn, Ce-Mn-Ti, Ce-Mn-Sn, Ce-Mn catalysts. From the figure, it can be seen that Ti⁴⁺、Sn⁴⁺Co-doped well to CeO₂In the crystal lattice, CeO is formed₂-MnO_x-TiO₂-SnO₂Solid solution.

FIG. 2 and Table 1 show H for Ce-Mn-Ti-Sn, Ce-Mn-Ti, Ce-Mn-Sn, Ce-Mn catalysts₂TPR results, Ti is shown in the figure and table⁴⁺、Sn⁴⁺Co-doping of the resulting CeO₂-MnO_x-TiO₂-SnO₂The redox performance of the catalyst is suitably diminished.

FIG. 3 and Table 2 show NH of Ce-Mn-Ti-Sn, Ce-Mn-Ti, Ce-Mn-Sn, Ce-Mn catalysts₃-TPD results. The graphs and tables show that Ti⁴⁺、Sn⁴⁺Co-doping of the resulting CeO₂-MnO_x-TiO₂-SnO₂The acid strength of the surface of the catalyst is enhanced, and the acid amount is increased.

FIG. 4 shows NH of Ce-Mn-Ti-Sn, Ce-Mn-Ti, Ce-Mn-Sn, Ce-Mn catalysts₃SCR reaction results, in which FIGS. 4(a) and (b) are NO for Ce-Mn-Ti-Sn, Ce-Mn-Ti, Ce-Mn-Sn, Ce-Mn catalysts, respectively_xConversion and N₂O formation concentration. As can be seen from the figure, Ti⁴⁺、Sn⁴⁺The co-doping can obviously improve the low-temperature denitration performance of the Ce-Mn catalyst and effectively inhibit the byproduct N₂And (4) generating O.

It was found that appropriate reduction of redox effectively inhibits NH₃Thereby reducing N₂The amount of O produced; the surface acid strength is enhanced, the acid amount is increased to be beneficial to NH₃The adsorption and activation, and further promote the promotion of low temperature denitration activity.

FIG. 5 shows CeO₂-MnO_x-TiO₂-SnO₂、CeO₂-MnO_x-TiO₂、CeO₂-MnO_x-SnO₂、CeO₂-MnO_xThe water-resistant and sulfur-resistant performance of the catalyst. As can be seen from the figure, Ti⁴⁺、Sn⁴⁺The co-doping can obviously enhance the water resistance and sulfur resistance of the Ce-Mn catalyst.

Table 1 shows CeO₂-MnO_x-TiO₂-SnO₂、CeO₂-MnO_x-TiO₂、CeO₂-MnO_x-SnO₂、CeO₂-MnO_xH of catalyst₂TPR quantitative analysis results.

Table 2 shows CeO₂-MnO_x-TiO₂-SnO₂、CeO₂-MnO_x-TiO₂、CeO₂-MnO_x-SnO₂、CeO₂-MnO_xNH of catalyst₃-TPD quantitative analysis results.

TABLE 1

TABLE 2

Application examples

The Ce-Mn-Ti-Sn, Ce-Mn-Ti, Ce-Mn-Sn and Ce-Mn catalysts prepared in the examples are applied to NH₃-SCR reaction, Ti⁴⁺、Sn⁴⁺The co-doped Ce-Mn-Ti-Sn catalyst can react with a byproduct N at the temperature of 50-275 DEG C₂The generation inhibition effect of O is most obvious, and the denitration activity is improved at the temperature of 225-275 ℃. The results are shown in FIG. 4.

The specific reaction conditions are as follows: the catalytic reaction performance data is measured in a fixed bed continuous flow quartz reactor, the granularity of the catalyst is 40-60 meshes, the dosage is 200mg, and the reaction gas comprises the following components: 500ppm NO, 500ppm NH ₃5% (volume percent) O₂，N₂The total flow of gas is 200mL/min for balance gas, and the reaction space velocity is 60000 mL/g.h. Before reaction, high-purity N is used₂Activating catalyst at 300 deg.C for 1h, performing catalytic reaction at 50-275 deg.C, collecting catalytic performance data once per liter of 25 deg.C after reaction reaches equilibrium, detecting and analyzing product in Thermofeisher IS10FTIR equipped with 200mL gas cell (optical path length 2m), maintaining the temperature of 150 deg.C from quartz reactor outlet to infrared gas cell to avoid NH₄NO₃Etc. and NH₃Dissolution in liquid water.

The high-efficiency multi-element CeO prepared by the invention₂-MnO_x-TiO₂-SnO₂The denitration catalyst is respectively reduced by X-ray diffraction (XRD) and hydrogen-temperature programming (H)₂TPR), ammonia gas-temperature programmed desorption (NH)₃TPD) and catalytic Performance test (NH)₃-SCR reverseShould) and the like to evaluate the bulk structure, reducing property, surface acidity and catalytic performance. The results are shown in the attached drawings. XRD results in FIG. 1 show that Ti is present in the invention⁴⁺、Sn⁴⁺Can be well codoped to CeO₂In the crystal lattice, CeO is formed₂-MnO_x-TiO₂-SnO₂Solid solution, enhancing the interaction between the components, by reaction with CeO₂XRD Standard card comparison of (C), CeO₂The main peak shifts to the right, mainly due to Ti with a smaller ionic radius⁴⁺

And Sn⁴⁺

Into CeO₂The crystal lattice of (2) replaces part of Ce⁴⁺

Thereby, the effect is achieved. H in FIG. 2₂TPR results and quantitative analysis results in Table 1 indicate that Ti is present in the invention⁴⁺、Sn⁴⁺Co-doping of the resulting CeO₂-MnO_x-TiO₂-SnO₂The redox performance of the catalyst is suitably diminished. NH in FIG. 3₃TPD results and quantitative analysis results in Table 2 show that Ti is present in the invention⁴⁺、Sn⁴⁺Co-doping of the resulting CeO₂-MnO_x-TiO₂-SnO₂The acid strength of the surface of the catalyst is enhanced, and the surface acid amount is increased. NH in FIG. 4₃The results of the SCR reaction show that Ti is passed through⁴⁺、Sn⁴⁺Codoping the resulting CeO₂-MnO_x-TiO₂-SnO₂The low-temperature denitration activity of the catalyst is obviously improved, and N is₂The generation of O is obviously inhibited, which is mainly combined with the solid solution structure, stronger interaction among the components and moderate reduction of oxidation-reduction capability, and NH is inhibited₃Non-selective catalytic oxidation and improvement of surface acidity. The results of the water and sulfur resistance performance in FIG. 5 show that Ti is passed through⁴⁺、Sn⁴⁺Codoping the resulting CeO₂-MnO_x-TiO₂-SnO₂The catalyst shows excellent water-resistant and sulfur-resistant performance, and shows that the catalyst has the potential of being applied to actual coal-fired flue gas denitration.

Example 2

Adding 10.5ml of LTiCl₄Dropwise adding the mixture into ultrapure water containing 2mL of concentrated hydrochloric acid under the condition of ice-water bath, and uniformly stirring the mixture by magnetic force to prepare TiCl with the concentration of 0.375mol/L₄A solution; SnCl₄·5H₂Dissolving O in ultrapure water containing 2mL concentrated hydrochloric acid to prepare 2mol/L SnCl₄A solution; 19.5017g of Ce (NO) are accurately weighed₃)₃·6H₂O、4.0185g Mn(NO₃)₂(50%) with the exact amount of TiCl as described above₄Solution (11.2mL) and SnCl₄The solution (28.1mL) is transferred into a beaker filled with ultrapure water (the volume of the solution is kept at 150mL) to be dissolved and mixed uniformly, and after the solution is stirred vigorously for 2 hours, the obtained mixed solution is slowly dripped into excessive concentrated ammonia water (25 percent) to ensure that the pH value is 10; continuously stirring the obtained suspension for 3h, aging for 24h, then carrying out suction filtration and water washing for several times until the pH value of the washing liquid is neutral, detecting that no precipitate appears in the washing liquid by using a silver nitrate solution, drying the obtained filter cake in a drying oven at 110 ℃ for 12h, naturally cooling to room temperature, taking out, grinding for 30min by using an agate mortar, placing in a muffle furnace, heating from the room temperature to 500 ℃ at the speed of 2 ℃/min under the flowing air atmosphere of 100mL/min, roasting for 5h, naturally cooling to room temperature, taking out, grinding for 30min in the agate mortar, and obtaining CeO₂、MnO_x、TiO₂、SnO₂CeO in a molar ratio of 6:2:1:1₂-MnO_x-TiO₂-SnO₂A catalyst.

Example 3

14mL of TiCl₄Dropwise adding the mixture into ultrapure water containing 2mL of concentrated hydrochloric acid under the condition of ice-water bath, and uniformly stirring the mixture by magnetic force to prepare TiCl with the concentration of 0.5mol/L₄A solution; SnCl₄·5H₂Dissolving O in ultrapure water containing 2mL concentrated hydrochloric acid to prepare 2mol/L SnCl₄A solution; 19.5017g of Ce (NO) are accurately weighed₃)₃·6H₂O、4.0185g Mn(NO₃)₂(50%) and the above TiC measured accuratelyl₄Solution (12.6mL) and SnCl₄The solution (28.1mL) is transferred into a beaker filled with ultrapure water (the volume of the solution is kept at 150mL) to be dissolved and mixed uniformly, and after the solution is stirred vigorously for 2 hours, the obtained mixed solution is slowly dripped into excessive concentrated ammonia water (25 percent) to ensure that the pH value is 10; continuously stirring the obtained suspension for 3h, aging for 24h, then carrying out suction filtration and water washing for several times until the pH value of the washing liquid is neutral, detecting that no precipitate appears in the washing liquid by using a silver nitrate solution, drying the obtained filter cake in a drying oven at 110 ℃ for 12h, naturally cooling to room temperature, taking out, grinding for 30min by using an agate mortar, placing in a muffle furnace, heating from the room temperature to 500 ℃ at the speed of 2 ℃/min under the flowing air atmosphere of 100mL/min, roasting for 5h, naturally cooling to room temperature, taking out, grinding for 30min in the agate mortar, and obtaining CeO₂、MnO_x、TiO₂、SnO₂CeO in a molar ratio of 9:2:1:1₂-MnO_x-TiO₂-SnO₂A catalyst.

CeO obtained in examples 2 to 3₂-MnO_x-TiO₂-SnO₂The catalyst performance was similar to example 1.

In conclusion, the catalyst prepared by the invention can generate N₂The inhibition effect of O is obvious, the denitration performance is obviously improved, the needed raw materials are cheap and easy to obtain, the preparation method is simple, the flow is clear, and the operation is safe.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A preparation method of a high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst is characterized by comprising the following steps:

1) dissolving a compound containing Ce, Mn, Ti and Sn elements in a proper amount of water to prepare a mixed solution for later use; what is needed isThe compound containing Ce, Mn, Ti and Sn elements is selected from Ce (NO)₃)₃、Mn(NO₃)₂、TiCl₄、SnCl₄In terms of mol, the ratio of Ce to Mn to Ti to Sn to (6-9) to 2 to 1;

2) slowly dripping the mixed solution prepared in the step 1) into excessive concentrated ammonia water, reacting until the mixed solution is completely precipitated to prepare a suspension, continuously stirring the obtained suspension for 2-3 hours, and then aging for more than 12 hours;

2. The method of claim 1, wherein: in the step 2), the mass fraction of the strong ammonia water is 25%; and/or in the step 2), the pH value of the suspension obtained by mixing the mixed solution and the strong ammonia water is more than or equal to 10.

3. The method of claim 2, wherein: in the step 2), the pH value of the suspension obtained by mixing the mixed solution and the strong ammonia water is 10-12.

4. The method of claim 1, wherein: the obtained suspension is continuously stirred for 2-3 h and then aged for 12-24 h.

5. The method of claim 1, wherein: in the step 3), the post-treatment specifically comprises washing, drying and roasting.

6. The method of claim 5, wherein: in the step 3), the obtained filter cake is washed until the pH value of a washing liquid is 7, and chloride ions cannot be detected by using a silver nitrate solution;

and/or, in the step 3), the roasting temperature is 350-650 ℃;

and/or in the step 3), the temperature rise rate during roasting is 1-2 ℃/min.

7. The high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst prepared by the preparation method according to any one of claims 1 to 6.

8. The high-efficiency multi-element Ce-Mn-Ti-Sn low-temperature denitration catalyst of claim 7 in NH₃-SCR reaction or low temperature denitration in coal-fired power plants.