A multi-metal oxide low-temperature desulfurization and denitration catalyst and a preparation method thereof

Abstract

The application provides a multi-metal oxide low-temperature desulfurization and denitration catalyst and a preparation method thereof, and relates to the field of catalyst preparation; the catalyst uses TiO2 as a catalyst carrier, Fe2O3, MnO2, CoO2, CeO2 and V2O5 as active components, and the active components are coated on the surface of the catalyst carrier; in the preparation, a deposition precipitation method is used, and the catalyst is obtained by step-by-step precipitation or impregnation and then calcination; the multi-metal oxide low-temperature desulfurization and denitration catalyst prepared by using the preparation method has good performances of removing nitrogen oxides and sulfides, and the catalyst has good stability and a simple preparation process without secondary pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a multi-metal oxide low-temperature desulfurization and denitrification catalyst and a preparation method thereof. Background Art

[0002] Coal, currently a major energy source, continuously emits sulfur oxides and nitrogen oxides. SO2 readily dissolves in water to form H2SO3, which further oxidizes to H2SO4, forming acid rain. Acid rain severely damages the ecological environment and corrodes building steel. Untreated emissions can cause significant economic losses. NOx, primarily NO and NO2, is a major contributor to photochemical smog and acid rain.

[0003] Sulfide and nitrogen oxides not only cause soil acidification, slow plant and animal growth, acidify water bodies, and corrode buildings, but they also harm human health. For example, SO2 is a strong irritant to the upper respiratory tract mucosa and conjunctiva, causing respiratory diseases such as pneumonia, bronchitis, and even pulmonary edema and respiratory paralysis. NOx is harmful to the human body by binding to hemoglobin in the blood, causing methemoglobinemia and other diseases, as well as central nervous system damage, resulting in symptoms such as paralysis and spasms, and even, in severe cases, lesions of the lungs and other respiratory organs. NO2 can also cause diseases such as asthma. Therefore, reducing and controlling SO2 and NOx emissions in flue gas is urgent.

[0004] Sulfur dioxide and nitrogen oxides are present simultaneously in flue gas. Separate removal methods would require large floor space, require extensive equipment, be complex to operate, and yield poor economic returns. However, since both gases are acidic oxides, simultaneous removal is feasible. Currently, integrated flue gas desulfurization and denitrification primarily consists of wet, dry, and semi-dry methods. While wet removal offers superior results, it also carries significant wastewater pollution. Dry removal is expensive, while semi-dry removal offers advantages over both dry and wet methods, but suffers from operational instability.

[0005] Prior art proposes a variety of catalysts for desulfurization and denitrification. For example, patent CN103691476B discloses a low-temperature simultaneous flue gas desulfurization and denitrification catalyst. This catalyst precursor is prepared by mixing mesoporous SBA-15, nano-titanium dioxide (anatase), and various metal oxides (Mn, V, Cr, Ce, W, Mo), ammonia, and deionized water. The catalyst is then further mixed and molded using a reinforcing agent, glass fiber, a crosslinker, 2-hydroxyethyl methacrylate, a surfactant, stearic acid, and a thermal stabilizer. The catalyst is then calcined to produce a porous catalyst. Patent CN105642339B discloses a simultaneous desulfurization and denitrification catalyst that does not require reducing gas. This catalyst utilizes a ZSM-5 molecular sieve carrier and active components such as CuO, K2O, CoO, Ni2O3, V2O5, and WO3. The catalyst is obtained by single or multiple impregnation processes, followed by drying and calcination. Summary of the Invention

[0006] The present invention aims to provide a multi-metal oxide low-temperature desulfurization and denitrification catalyst and a preparation method thereof. The method comprises the following steps: first, a precipitation method is used to precipitate part of the active components in steps, and then the remaining active components are impregnated by an impregnation method to obtain the catalyst. The method has simple procedures, readily available raw materials, a stable catalyst structure, excellent catalytic performance, and does not cause secondary pollution.

[0007] To achieve the above objectives, the present invention proposes the following technical solutions:

[0008] In the first aspect, a multi-metal oxide low-temperature desulfurization and denitrification catalyst is provided, comprising: a catalyst carrier, TiO2; active components, Fe2O3, MnO2, CoO2, CeO2 and V2O5; the active components are coated on the surface of the catalyst carrier, and the molar ratio of each metal element in the catalyst is Ti:Mn:Co:Ce:Fe:V=100:(6-8):(1-2):(1-2):(1-3):(1-3); preferably, the molar ratio of each metal element is: Ti:Mn:Co:Ce:Fe:V=100:6:2:2:3:3.

[0009] A method for preparing the above-mentioned multi-metal oxide low-temperature desulfurization and denitrification catalyst is provided. This method first obtains a catalyst carrier TiO2 and a mixture of metal salts corresponding to the active components Fe2O3, MnO2, CoO2, and CeO2 by distributed precipitation. The metal salt corresponding to V2O5 is loaded on the surface of a first calcined product after calcining the metal salt mixture by an impregnation method. Finally, the first calcined product with the metal salt corresponding to V2O5 on the surface is calcined a second time to obtain a multi-metal oxide low-temperature desulfurization and denitrification catalyst.

[0010] Furthermore, the method comprises the following steps:

[0011] 1) dissolving Ti salt and Fe salt weighed in proportion and mixing with excess alkaline precipitant for reaction, maintaining the pH of the reaction solution at 9-10 until the reaction is completed to obtain a first reaction solution;

[0012] 2) Using a sedimentation precipitation method, the Mn salt, Co salt, and Ce salt weighed in proportion are sequentially added to the first reaction solution to continue the reaction, maintaining the pH of the reaction solution at 9-10 until the reaction is complete to obtain a second reaction solution;

[0013] 3) aging, washing, drying, calcining, and then forming tablets of the solid product of the second reaction solution to obtain a first calcined product;

[0014] 4) Immersing an equal volume of the first calcined product in a mixed solution of ammonium metavanadate and acid prepared in a certain proportion, and allowing to stand for 3-4 hours to obtain a third reaction solution;

[0015] 5) washing, drying, and calcining the solid product of the third reaction solution to obtain a multi-metal oxide low-temperature desulfurization and denitrification catalyst.

[0016] Furthermore, the alkaline precipitant in step 1) is Na2CO3, NaHCO3, K2CO3 or KHCO3.

[0017] Furthermore, the aging time of the solid product of the second reaction solution in step 3) is 4-6 hours.

[0018] Furthermore, the standard for washing the solid product of the second reaction solution in step 3) is to wash the solution until the pH value is 7.0 and no blue color is developed after adding five drops of diphenylamine sulfuric acid solution.

[0019] Furthermore, the acid in step 4) is oxalic acid.

[0020] Furthermore, the drying standards of the product in step 3) and step 5) are: drying temperature 100-120° C., and weight loss after drying 80-82%.

[0021] Furthermore, the product is calcined in step 5) at a temperature of 450-480° C. for 4-6 hours.

[0022] It can be seen from the above technical solutions that the technical solutions of the present invention have the following beneficial effects:

[0023] The present invention discloses a multi-metal oxide low-temperature desulfurization and denitrification catalyst and a preparation method thereof, wherein the catalyst uses TiO2 as a catalyst carrier, Fe2O3, MnO2, CoO2, CeO2 and V2O5 as active components, the active components are coated on the surface of the catalyst carrier, and the molar ratio of each metal element in the catalyst is Ti:Mn:Co:Ce:Fe:V=100:(6-8):(1-2):(1-2):(1-3):(1-3); during preparation, the catalyst carrier TiO2 and the active components Fe2O3, MnO2, CoO2, CeO2 and V2O5 are first obtained by distributed precipitation. A metal salt mixture corresponding to V2O5 is prepared, and a metal salt corresponding to V2O5 is loaded on the surface of a first calcined product after the metal salt mixture is calcined by an impregnation method. Finally, the first calcined product with the metal salt corresponding to V2O5 loaded on the surface is calcined for a second time to obtain a multi-metal oxide low-temperature desulfurization and denitrification catalyst. The multi-metal oxide low-temperature desulfurization and denitrification catalyst prepared by the preparation method disclosed in the present invention does not form a solid solution compound when obtained by calcination. When used in desulfurization and denitrification reactions, it has good performance in removing nitrogen oxides and sulfides. A large number of experiments have verified that the catalyst of the present invention has good stability and no secondary pollution.

[0024] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, to the extent such concepts are not mutually inconsistent, can be considered to be part of the inventive subject matter of this disclosure.

[0025] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of the exemplary embodiments, will become apparent from the following description or through practice of specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0027] Figure 1 This is a flow chart of the preparation method of the multi-metal oxide low-temperature desulfurization and denitrification catalyst of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described 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. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0029] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular form of "a", "an" or "the" and similar words do not indicate a quantity limitation, but rather indicate the presence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0030] The current integrated flue gas desulfurization and denitrification processes mainly include wet desulfurization and denitrification, dry desulfurization and denitrification, and semi-dry desulfurization and denitrification. Although dry desulfurization and denitrification has high operating costs, it has long been a research focus due to its lack of waste liquid and stable performance. This invention aims to provide a multi-metal oxide low-temperature desulfurization and denitrification catalyst for dry desulfurization and denitrification, and its preparation method. This catalyst features simple process flow, high efficiency and stability in desulfurization and denitrification, low cost, and no secondary pollution.

[0031] Specifically, the preparation method of the multi-metal oxide low-temperature desulfurization and denitrification catalyst includes the following steps: 1) dissolving Ti salt and Fe salt weighed in proportion and mixing them with excess alkaline precipitant to react, maintaining the pH of the reaction solution at 9-10 until the reaction is completed to obtain a first reaction solution; wherein, the alkaline precipitant is Na2CO3, NaHCO3, K2CO3 or KHCO3; 2) using a sedimentation precipitation method, adding Mn salt, Co salt and Ce salt weighed in proportion to the first reaction solution in sequence to continue the reaction, maintaining the pH of the reaction solution at 9-10 until the reaction is completed to obtain a second reaction solution; wherein, when adding the next metal salt, it is necessary to stir the reaction of the previous metal salt for 0.5-1h; 3) aging the solid product of the second reaction solution for 4-6h, washing, After drying and calcining, the product is formed into sheets to obtain a first calcined product. 4) The first calcined product is immersed in an equal volume of a mixed solution of ammonium metavanadate and an acid in a proportioned manner and allowed to stand for 3-4 hours to obtain a third reaction solution. The acid is oxalic acid. 5) The solid product of the third reaction solution is washed, dried, and calcined to obtain a multi-metal oxide low-temperature desulfurization and denitrification catalyst. The catalyst comprises: a catalyst support, TiO2; and active components, Fe2O3, MnO2, CoO2, CeO2, and V2O5. The active components are coated on the surface of the catalyst support, and the molar ratio of the metal elements in the catalyst is Ti:Mn:Co:Ce:Fe:V = 100:(6-8):(1-2):(1-2):(1-3):(1-3). In the above steps, the Ti salt, Fe salt, Mn salt, Co salt, and Ce salt are all nitrates.

[0032] The following is a further detailed introduction to the multi-metal oxide low-temperature desulfurization and denitrification catalyst and its preparation method disclosed in the present invention in conjunction with the specific processes and embodiments shown in the accompanying drawings.

[0033] The multi-metal oxide low-temperature desulfurization and denitrification catalyst disclosed in the present invention uses titanium dioxide as a catalyst carrier and contains manganese, cobalt, cerium, iron, and vanadium as active ingredients. During preparation, the multi-metal oxide does not form a solid solution compound after calcination. The advantage of this method is that the active components are precipitated step by step using a precipitation method, and then impregnated with the active components using an impregnation method to finally obtain the catalyst. The preparation parameters of the optimal catalyst are determined through a large number of examples as follows, and this optimal catalyst has excellent desulfurization and denitrification effects.

[0034] Example 1

[0035] Add a mixed solution containing Ti(NO3)4 and Fe(NO3)3 to water concurrently with a Na2CO3 solution, stirring for 0.5-1 hour. Add Mn(NO3)2 solution to the above solution, then add additional Na2CO3 solution, maintaining the pH of the solution at 9-10, and continue stirring for 0.5-1 hour. Add Co(NO3)2 solution to the above solution, then add additional Na2CO3 solution, maintaining the pH of the solution at 9-10, and continue stirring for 0.5-1 hour. Add Ce(NO3)2 solution to the above solution, then add additional Na2CO3 solution, maintaining the pH of the solution at 9-10, and continue stirring for 0.5-1 hour. The molar ratio of the catalyst's components, Ti:Mn:Co:Ce:Fe, is 100:8:1:1:1. The precipitate was aged for 4 hours, washed with five drops of diphenylamine sulfuric acid solution, dried at 120°C until it lost 80% weight, programmed to 460°C for calcination for 4 hours, and then formed into tablets. Oxalic acid and ammonium metavanadate solutions were prepared in a 1:2 molar ratio, and the tablets were immersed in the ammonium oxalic acid metavanadate solution for 3 hours. The solution was then washed, calcined at 450°C for 3 hours, and decomposed to produce Catalyst I with a Ti:Mn:Co:Ce:Fe:V ratio of 100:8:1:1:1:2.

[0036] Example 2

[0037] Add a mixed solution containing Ti(NO3)4 and Fe(NO3)3 to water concurrently with a NaHCO3 solution, stirring for 0.5-1 hour. Add Mn(NO3)2 solution to the above solution, then add additional NaHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Co(NO3)2 solution to the above solution, then add additional NaHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Ce(NO3)2 solution to the above solution, then add additional NaHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. The molar ratio of the catalyst's components, Ti:Mn:Co:Ce:Fe, is 100:6:1.5:2:1. The precipitate was aged for 4 hours, washed with five drops of diphenylamine sulfuric acid solution, dried at 120°C to a weight loss of 82%, programmed to 480°C for 4 hours, and then pelletized. Oxalic acid and ammonium metavanadate solutions were prepared in a 1:2 molar ratio, and the pelletized catalyst was immersed in the ammonium oxalic acid metavanadate solution for 3 hours. The pellet was then washed and calcined at 460°C for 3 hours. Catalyst II was then decomposed to produce a Ti:Mn:Co:Ce:Fe:V ratio of 100:6:1.5:2:1:2.

[0038] Example 3

[0039] Add a mixed solution containing Ti(NO3)4 and Fe(NO3)3 to water concurrently with a K2CO3 solution, stirring for 0.5-1 hour. Add a Mn(NO3)2 solution to the above solution, followed by additional K2CO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add a Co(NO3)2 solution to the above solution, followed by additional K2CO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add a Ce(NO3)2 solution to the above solution, followed by additional K2CO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. The molar ratio of the catalyst elements Ti:Mn:Co:Ce:Fe is 100:8:1:1:1. The precipitate was aged for 4 hours, washed until it was blue with five drops of diphenylamine sulfuric acid solution, dried at 120°C until it lost 80% weight, programmed to 460°C for calcination for 4 hours, and then formed into tablets. Oxalic acid and ammonium metavanadate solutions were prepared in a 1:2 molar ratio, and the tablets were immersed in the ammonium oxalic acid metavanadate solution for 3 hours. The tablets were then washed, calcined at 450°C for 3 hours, and decomposed to produce Catalyst III with a Ti:Mn:Co:Ce:Fe:V ratio of 100:8:1:1:1:1.

[0040] Example 4

[0041] Add a mixed solution containing Ti(NO3)4 and Fe(NO3)3 to water concurrently with a KHCO3 solution, stirring for 0.5-1 hour. Add Mn(NO3)2 solution to the above solution, followed by additional KHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Co(NO3)2 solution to the above solution, followed by additional NaHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Ce(NO3)2 solution to the above solution, followed by additional KHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. The molar ratio of the catalyst elements Ti:Mn:Co:Ce:Fe is 100:6:2:2:3. The precipitate was aged for 4 hours, washed with five drops of diphenylamine sulfuric acid solution, dried at 120°C until it lost 80% weight, programmed to 460°C for calcination for 4 hours, and then pelletized. Oxalic acid and ammonium metavanadate solutions were prepared in a 1:2 molar ratio, and the pelletized catalyst was immersed in the ammonium oxalic acid metavanadate solution for 4 hours. The pelletized catalyst was then washed and calcined at 450°C for 5 hours. Catalyst IV was prepared by decomposition with a Ti:Mn:Co:Ce:Fe:V ratio of 100:6:2:2:3:3.

[0042] Example 5

[0043] Add a mixed solution containing Ti(NO3)4 and Fe(NO3)3 to water concurrently with a K2CO3 solution, stirring for 0.5-1 hour. Add Mn(NO3)2 solution to the above solution, followed by additional KHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Co(NO3)2 solution to the above solution, followed by additional NaHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Ce(NO3)2 solution to the above solution, followed by additional KHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. The molar ratio of the catalyst elements Ti:Mn:Co:Ce:Fe is 100:8:2:2:3. The precipitate was aged for 4 hours, washed with five drops of diphenylamine sulfuric acid solution, dried at 120°C to a weight loss of 81%, programmed to 480°C for 6 hours, and then pelletized. Oxalic acid and ammonium metavanadate solutions were prepared in a 1:2 molar ratio, and the pelletized catalyst was immersed in the ammonium oxalic acid metavanadate solution for 3 hours. The pellet was then washed and calcined at 450°C for 4 hours. Catalyst V was prepared by decomposition with a Ti:Mn:Co:Ce:Fe:V ratio of 100:8:2:2:3:3.

[0044] Example 6

[0045] Add a mixed solution containing Ti(NO3)4 and Fe(NO3)3 to water concurrently with a K2CO3 solution, stirring for 0.5-1 hour. Add Mn(NO3)2 solution to the above solution, followed by additional K2CO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Co(NO3)2 solution to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Ce(NO3)2 solution to the above solution, followed by additional K2CO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. The molar ratio of the catalyst's components, Ti:Mn:Co:Ce:Fe, is 100:6:1:1:3. The precipitate was aged for 4 hours, washed with five drops of diphenylamine sulfuric acid solution, dried at 120°C to a weight loss of 81%, programmed to 480°C for 4 hours, and then pelletized. Oxalic acid and ammonium metavanadate solutions were prepared in a 1:2 molar ratio, and the pelletized catalyst was immersed in the ammonium oxalic acid metavanadate solution for 4 hours. The pelletized catalyst was then washed and calcined at 450°C for 4 hours. Catalyst VI was prepared by decomposition with a Ti:Mn:Co:Ce:Fe:V ratio of 100:6:1:1:3:3.

[0046] Example 7

[0047] Add a mixed solution containing Ti(NO3)4 and Fe(NO3)3 to water concurrently with a NaHCO3 solution, stirring for 0.5-1 hour. Add Mn(NO3)2 solution to the above solution, then add additional NaHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Co(NO3)2 solution to the above solution, then add additional NaHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Ce(NO3)2 solution to the above solution, then add additional NaHCO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. The molar ratio of the catalyst's components, Ti:Mn:Co:Ce:Fe, is 100:6:1:1:1. The precipitate was aged for 4 hours, washed with five drops of diphenylamine sulfuric acid solution, dried at 120°C to a weight loss of 81%, programmed to 480°C for 6 hours, and then pelletized. Oxalic acid and ammonium metavanadate solutions were prepared in a 1:2 molar ratio, and the pelletized catalyst was immersed in the ammonium oxalic acid metavanadate solution for 3.5 hours. The pellet was then washed and calcined at 450°C for 4 hours. Catalyst VII was prepared by decomposition with a Ti:Mn:Co:Ce:Fe:V ratio of 100:6:1:1:1:1.

[0048] Comparative Example 1

[0049] A mixed solution containing Ti(NO3)4 and Fe(NO3)3 is added to water concurrently with a Na2CO3 solution, stirred for 0.5-1 hour. Co(NO3)2 solution is added to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and stirring for 0.5-1 hour. Ce(NO3)2 solution is added to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and stirring for 0.5-1 hour. The catalyst has a molar ratio of Ti:Co:Ce:Fe of 100:1:1:1. The precipitate is aged for 4 hours, washed until it is blue with five drops of diphenylamine sulfuric acid solution, dried at 120°C until it loses 80% weight, programmed to 460°C for calcination for 4 hours, and finally formed into tablets. Oxalic acid and ammonium metavanadate solution were prepared in a molar ratio of 1:2, and the tableted catalyst was immersed in the ammonium oxalic acid metavanadate solution for 4 hours. The catalyst was washed and calcined at 450°C for 3 hours. The catalyst A with a Ti:Co:Ce:Fe:V ratio of 100:1:1:1:2 was obtained by decomposition.

[0050] Comparative Example 2

[0051] A mixed solution containing Ti(NO3)4 and Fe(NO3)3 is added to water concurrently with a K2CO3 solution, stirred for 0.5-1 hour. Co(NO3)2 solution is added to the above solution, followed by additional K2CO3 solution, maintaining the pH at 9-10, and stirring for 0.5-1 hour. Ce(NO3)2 solution is added to the above solution, followed by additional K2CO3 solution, maintaining the pH at 9-10, and stirring for 0.5-1 hour. The catalyst's molar ratio of Ti:Co:Ce:Fe is 100:2:2:3. The precipitate is aged for 4 hours, washed until it is blue with five drops of diphenylamine sulfuric acid solution, dried at 120°C until it loses 81% weight, programmed to 480°C for calcination for 6 hours, and then formed into tablets. Oxalic acid and ammonium metavanadate solution were prepared in a molar ratio of 1:2, and the tableted catalyst was immersed in the ammonium oxalic acid metavanadate solution for 3 hours, washed, calcined at 450°C for 4 hours, and decomposed to obtain catalyst B with a metal element ratio of Ti:Co:Ce:Fe:V=100:2:2:3:3.

[0052] Comparative Example 3

[0053] A mixed solution containing Ti(NO3)4 and Fe(NO3)3 is added to water concurrently with a Na2CO3 solution, stirred for 0.5-1 hour. Mn(NO3)2 solution is added to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and stirring for 0.5-1 hour. Ce(NO3)2 solution is added to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and stirring for 0.5-1 hour. The catalyst has a molar ratio of Ti:Mn:Ce:Fe of 100:8:1:1. The precipitate is aged for 4 hours, washed with five drops of diphenylamine sulfuric acid solution, dried at 120°C until 80% weight loss is achieved, programmed to 460°C for calcination for 4 hours, and then formed into tablets. Oxalic acid and ammonium metavanadate solution were prepared in a molar ratio of 1:2, and the tableted catalyst was immersed in the ammonium oxalic acid metavanadate solution for 3 hours, washed, calcined at 450°C for 3 hours, and decomposed to obtain catalyst C with a metal element ratio of Ti:Mn:Ce:Fe:V=100:8:1:1:2.

[0054] Comparative Example 4

[0055] A mixed solution containing Ti(NO3)4 and Fe(NO3)3 is added to water concurrently with a Na2CO3 solution, stirred for 0.5-1 hour. Mn(NO3)2 solution is added to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and stirring for 0.5-1 hour. Co(NO3)2 solution is added to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and stirring for 0.5-1 hour. The catalyst has a molar ratio of Ti:Mn:Co:Fe of 100:8:1:1. The precipitate is aged for 4 hours, washed with five drops of diphenylamine sulfuric acid solution, dried at 120°C until 80% weight loss is achieved, programmed to 460°C for calcination for 4 hours, and finally formed into tablets. Oxalic acid and ammonium metavanadate solution were prepared in a molar ratio of 1:2, and the tableted catalyst was immersed in the ammonium oxalic acid metavanadate solution for 3 hours, washed, calcined at 450°C for 3 hours, and decomposed to obtain catalyst D with a metal element composition of Ti:Mn:Co:Fe:V=100:8:1:1:2.

[0056] Comparative Example 5

[0057] Add a solution containing Ti(NO3)4 and a Na2CO3 solution concurrently to water, stirring for 0.5-1 hour. Add Mn(NO3)2 solution to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Co(NO3)2 solution to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. Add Ce(NO3)2 solution to the above solution, followed by additional Na2CO3 solution, maintaining the pH at 9-10, and continue stirring for 0.5-1 hour. The catalyst has a molar ratio of Ti:Mn:Co:Ce of 100:8:1:1. The precipitate is aged for 4 hours, washed with five drops of diphenylamine sulfuric acid solution, dried at 120°C until 80% weight loss, programmed to 460°C for calcination for 4 hours, and finally formed into tablets. Oxalic acid and ammonium metavanadate solution were prepared in a molar ratio of 1:2, and the tableted catalyst was immersed in the ammonium oxalic acid metavanadate solution for 3 hours, washed, calcined at 450°C for 3 hours, and decomposed to obtain catalyst E with a metal element composition of Ti:Mn:Co:Ce:V=100:8:1:1:2.

[0058] Comparative Example 6

[0059] The mixed solution containing Ti (NO3)4, Fe (NO3)3and Na2CO3solution are added into water in parallel, stirred and maintained for 0.5-1h; Mn (NO3)2solution is added into the above solution, Na2CO3solution is added to maintain the pH of the solution at 9-10, and the stirring is continued for 0.5-1h. Ce (NO3)2solution is added into the above solution, Na2CO3solution is added to maintain the pH of the solution at 9-10, and the stirring is continued for 0.5-1h. The precipitate is aged for 4h, washed until five drops of diphenylamine sulfuric acid solution is not blue, dried at 120℃ until the weight loss is 80%, and then the temperature is programmed to 460℃ and calcined for 4h to obtain the catalyst F with the molar ratio of metal components of Ti:Mn:Co:Ce:Fe =100:8:1:1:1.

[0060] Catalyst performance evaluation

[0061] Catalysts I-VII and A-F are respectively filled in a fixed bed tube reactor, and the reaction conditions are as follows: pressure 0.2MPa, gas composition SO2800ppm, NO 600ppm, NH3900ppm, O2volume 5%, nitrogen as balance gas, space velocity 5000h-1, reaction temperature 240℃, and the outlet concentrations of SO2 and NO are tested. -1

[0062] Table 1 Catalyst performance test data

[0063]

[0064] As shown in Table 1, the catalysts with the metal element ratio of Ti:Mn:Co:Ce:Fe:V =100:(6-8):(1-2):(1-2):(1-3):(1-3) obtained in Examples 1-7 all have excellent desulfurization and denitrification effects, and the removal efficiency is high after a long time of operation. This shows that the catalysts of the present application still have high desulfurization and denitrification performance after a long time of operation, and the catalysts have good removal performance. The catalysts A and B obtained in Comparative Examples 1 and 2 do not contain Mn, and the removal efficiency is low after 1h and 4h of operation, which shows that the catalysts without Mn have poor desulfurization and denitrification performance. Comparative Examples 3-6 are catalysts without Co, Ce, Fe and V, respectively, and the removal efficiency of sulfur and nitrogen is poor when they are applied, which shows that the catalysts of the present application have excellent desulfurization and denitrification efficiency because of the synergistic effect of the active sites formed by the metal elements when they combine with sulfur dioxide and nitrogen oxides.

[0065] ​While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A multi-metal oxide low-temperature desulfurization and denitrification catalyst, characterized in that: include: Catalyst support, TiO2; Active components, Fe2O3, MnO2, CoO2, CeO2 and V2O5; The active component is coated on the surface of the catalyst support, and the molar ratio of the metal elements in the catalyst is Ti:Mn:Co:Ce:Fe:V=100:(6-8):(1-2):(1-2):(1-3):(1-3); The preparation comprises the following steps: 1) dissolving Ti salt and Fe salt weighed in proportion and mixing with excess alkaline precipitant for reaction, maintaining the pH of the reaction solution at 9-10 until the reaction is completed to obtain a first reaction solution; 2) Using a sedimentation precipitation method, the Mn salt, Co salt, and Ce salt weighed in proportion are sequentially added to the first reaction solution to continue the reaction, maintaining the pH of the reaction solution at 9-10 until the reaction is complete to obtain a second reaction solution; wherein, when adding the next metal salt, it is necessary to stir the previous metal salt for 0.5-1 hour; 3) aging, washing, drying, calcining, and then forming tablets of the solid product of the second reaction solution to obtain a first calcined product; 4) Immersing an equal volume of the first calcined product in a mixed solution of ammonium metavanadate and acid prepared in a certain proportion, and allowing to stand for 3-4 hours to obtain a third reaction solution; 5) washing, drying, and calcining the solid product of the third reaction solution to obtain a multi-metal oxide low-temperature desulfurization and denitrification catalyst.

2. A method for preparing a multi-metal oxide low-temperature desulfurization and denitrification catalyst, characterized in that: The steps include: 1) dissolving Ti salt and Fe salt weighed in proportion and mixing with excess alkaline precipitant for reaction, maintaining the pH of the reaction solution at 9-10 until the reaction is completed to obtain a first reaction solution; 2) Using a sedimentation precipitation method, the Mn salt, Co salt, and Ce salt weighed in proportion are sequentially added to the first reaction solution to continue the reaction, maintaining the pH of the reaction solution at 9-10 until the reaction is complete to obtain a second reaction solution; wherein, when adding the next metal salt, it is necessary to stir the previous metal salt for 0.5-1 hour; 3) aging, washing, drying, calcining, and then forming tablets of the solid product of the second reaction solution to obtain a first calcined product; 4) Immersing an equal volume of the first calcined product in a mixed solution of ammonium metavanadate and acid prepared in a certain proportion, and allowing to stand for 3-4 hours to obtain a third reaction solution; 5) washing, drying, and calcining the solid product of the third reaction solution to obtain a multi-metal oxide low-temperature desulfurization and denitrification catalyst.

3. The method for preparing a multi-metal oxide low-temperature desulfurization and denitrification catalyst according to claim 2, characterized in that: In the step 1), the alkaline precipitant is Na2CO3, NaHCO3, K2CO3 or KHCO3.

4. The method for preparing a multi-metal oxide low-temperature desulfurization and denitrification catalyst according to claim 2, characterized in that: The aging time of the solid product of the second reaction solution in step 3) is 4-6 hours.

5. The method for preparing a multi-metal oxide low-temperature desulfurization and denitrification catalyst according to claim 2, characterized in that: The standard for washing the solid product of the second reaction solution in step 3) is to wash until the pH of the solution reaches 7.0 and no blue color is observed after adding five drops of diphenylamine sulfuric acid solution.

6. The method for preparing a multi-metal oxide low-temperature desulfurization and denitrification catalyst according to claim 2, characterized in that: The acid in step 4) is oxalic acid.

7. The method for preparing a multi-metal oxide low-temperature desulfurization and denitrification catalyst according to claim 2, characterized in that: The drying standards of the product in step 3) and step 5) are: drying temperature 100-120° C., and weight loss after drying 80-82%.

8. The method for preparing a multi-metal oxide low-temperature desulfurization and denitrification catalyst according to claim 2, characterized in that: The conditions for calcining the product in step 5) are: calcination temperature 450-480° C., calcination 4-6 hours.

9. The method for preparing a multi-metal oxide low-temperature desulfurization and denitrification catalyst according to claim 2, characterized in that: The molar ratio of each metal element in the multi-metal oxide low-temperature desulfurization and denitrification catalyst is: Ti:Mn:Co:Ce:Fe:V=100:6:2:2:3:3.

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