A desulfurization and denitration porous catalyst

Abstract

The present application relates to a kind of desulfurization denitration porous catalyst, catalyst with manganese oxide MO as the porous carrier of denitration, and the porous carrier provides loading site for active desulfurization catalyst vanadium oxide and cerium oxide.Catalyst is expressed as MO / Ce,V, MO is obtained by high-temperature calcination of metal organic framework compound, select MO porous matrix, then by step-by-step solution method load CeO2 With V2O5 Desulfurization active area is divided, and higher desulfurization denitration conversion efficiency is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of industrial catalysis, and particularly relates to a desulfurization and denitrification porous catalyst for flue gas treatment. TECHNICAL BACKGROUND

[0002] Excessive emission of SO2 and NOx in industrial production process will cause various environmental problems such as acid rain, photochemical smog, ozone layer destruction and greenhouse effect, which affect human life, health and safety, so that countries have put forward strict requirements for control technology of atmospheric pollutants emission of coal-fired power plants. In most coal-fired power plants, dust removal, desulfurization and denitrification devices are installed for segmented treatment, and this process for treating pollutants has the advantages of strong selectivity and relative stability. In order to improve the treatment effect and shorten the process, researchers have invented a flue gas simultaneous desulfurization and denitrification technology, which can remove SO2 and NOx simultaneously in a flue gas treatment unit. Among them, the representative methods include adsorption regeneration technology, plasma technology, catalytic reduction technology and catalytic oxidation technology.

[0003] The catalytic reduction technology is to install an activated reduced catalyst in a reactor, and to introduce reducing gases such as H2, CH4, NH3 and CO, so that when the polluted flue gas passes through, the reducing catalyst combines with the reducing gas to react with SO2 and NOx in the polluted flue gas. SO2 in the polluted flue gas will be reduced to S element, which can be recycled and reused after treatment. NOx in the polluted flue gas will be reduced to N2, which will not pollute the atmosphere, and can be directly discharged into the atmosphere after the reaction. Commonly used catalysts are noble metal elements such as Pd and Pt, transition metal, rare earth element catalysts and perovskite type and solid solution type catalysts.

[0004] The catalytic oxidation technology is to oxidize SO2 in the polluted flue gas into SO3, and to oxidize NO into higher valence state NOx, which is then removed by absorption in the subsequent device. In the process of catalytic reaction, no reducing gas is used, and the oxidation catalyst used at present does not use noble metal elements, which saves a lot of cost. Commonly used catalysts include iron oxide catalysts and manganese oxide catalysts.

[0005] Manganese oxide catalysts mainly have good activity in the process of oxidation denitrification due to the multiple chemical valence states of manganese (Mn2+, Mn3+, Mn4+). The preparation of manganese oxide catalysts is often to load the active component on the Al2O3 carrier, and the activity is subject to factors such as loading amount and loading method. Although the existing flue gas desulfurization and denitrification technology has more active components, it still has problems of low efficiency and complex material preparation process. SUMMARY

[0006] To achieve the above object, the present application provides a desulfurization and denitrification porous catalyst, the catalyst uses manganese oxide MO as a denitrification porous carrier, and the porous carrier provides loading sites for active desulfurization catalysts vanadium oxide and cerium oxide.

[0007] A desulfurization and denitrification porous catalyst, the catalyst MO / Ce,V, uses a porous manganese oxide MO as a base body, and loads V2O5 and CeO2.

[0008] The molar content of V2O5 and CeO2 relative to the porous manganese oxide MO is 0.01-0.05, 0.01-0.05.

[0009] The porous manganese oxide base body is a honeycomb-like porous structure.

[0010] The V2O5 and CeO2 are loaded on the surface of the porous manganese oxide.

[0011] The specific surface area of the catalyst is 65.1 m 2 / g, and the porosity is 0.52 cm 3 / g.

[0012] The desulfurization efficiency and denitrification efficiency of the porous catalyst are respectively 85% and 94% or more.

[0013] The present application also provides a preparation method of a desulfurization and denitrification porous catalyst, which comprises the preparation of a porous manganese oxide MO base body, dissolving an organic manganese source and terephthalic acid in a solvent, then performing a solvent thermal reaction in a high-pressure reaction kettle, and then placing the product after separation in a high-temperature furnace for calcination.

[0014] The preparation method also comprises loading of the porous manganese oxide MO base body, and the loading method is to disperse the calcination product in a vanadium salt solution, heat and stir, and then calcine; disperse the calcination product in a cerium salt solution, perform microwave ultrasonic reaction, and then calcine to obtain the catalyst.

[0015] The organic manganese source is selected from manganese nitrate, manganese chloride, and manganese acetate; the solvent is selected from DMF, ethanol, and methanol; the solvent thermal temperature is 100-180 DEG C, and the solvent thermal time is 10-18 h; and the molar ratio of the organic manganese source to terephthalic acid is 1:2-2:1.

[0016] The vanadium salt solution is a mixed solution of ammonium metavanadate and oxalic acid, and the molar ratio of the two is 1:1.

[0017] The heating and stirring conditions are 60 DEG C temperature heating and stirring for 3 h;

[0018] The calcination and the calcination process conditions are the same, and the temperature is raised to 300 DEG C at a temperature rising rate of 5 DEG C / min, and the temperature is kept for 4h.

[0019] The porous manganese oxide MO of the application is an organic metal framework structure formed by organic manganese salt and ligand terephthalic acid under high temperature and high pressure, and the framework structure compound is calcined to form a porous morphology, and the manganese oxide actually mainly exists in the form of Mn3O4 and Mn2O3, which is a catalyst component for flue gas denitrification, has the characteristics of super-high specific surface area, hierarchical pore size distribution and chemical stability, the prepared nanoparticle size is more uniform after calcination, the dispersibility is better, and the original porosity and morphology of the template are maintained. The porous structure is not only used as a carrier for subsequent loading of a desulfurization active component, but also used as a catalytic channel for denitrification.

[0020] The desulfurization active component V2O5 is selected in the application, mainly because V2O5 has an active coordination site, so it has strong redox capacity, can oxidize SO2 into SO3 and then reduce itself to maintain its properties unchanged. The element V is easy to react with metal oxides on the surface of MO. The desulfurization active component V2O5 is prepared by reacting ammonium metavanadate with oxalic acid, and the active component V2O5 and the auxiliary agent CeO2 are loaded by using a separate impregnation method, instead of directly mixing vanadium salt and cerium salt, which is to avoid the reaction of oxalic acid with CeO2.

[0021] The application selects CeO2 as an auxiliary agent of the desulfurization catalyst, which is based on the fact that the oxide of cerium has good oxygen storage characteristics, so that the catalyst has good redox capacity. After the reaction of V2O5 and CeO2, the element Ce exists in the form of Ce3+, which is different from CeO2. At the same time, the element V is easy to react with CeO2 to generate V-O-Ce bond, so that the catalytic activity of the V-based catalyst is improved, and the catalytic capacity of the catalyst is greatly improved. In addition, when the framework structure of MO is used as a matrix, V2O5 and CeO2 can be uniformly distributed on the framework structure of MO, the catalyst has good dispersibility, the overall structure is stable, the addition of the auxiliary agent is beneficial to the loading of vanadium element, the improvement of the MO catalyst is further improved, and it is helpful to improve the SO2 removal efficiency.

[0022] The MO catalyst is prepared by a pyrolysis method: first, the organic manganese and terephthalic acid are dissolved in DMF respectively. After ultrasonic treatment and stirring, the mixed solution is transferred to a polytetrafluoroethylene reaction kettle for high-temperature reaction for a certain time, and then the precipitate is collected by centrifugation, washed and dried. The obtained white powder of the metal organic framework compound is placed in a tube furnace and heated to 300 DEG C. A black powder, namely the manganese oxide catalyst MO, is obtained.

[0023] Take manganese oxide catalyst MO, disperse in deionized water, add vanadate and oxalic acid solution. Heat and stir to mix well, vacuum drying, grinding, and then placed in a dry clean ceramic crucible in the muffle furnace.

[0024] Take the calcined product, uniformly disperse it in deionized water, then take a certain amount of cerium metal salt and add it to the above dispersion, ultrasonic treatment at room temperature, and continuous stirring. After standing at room temperature, remove the supernatant. The obtained lower solid precipitate is placed in an oven. After drying, the sample is ground into powder and placed in a tube furnace for calcination. After the reaction is completed, the sample is cooled to room temperature to obtain a black powder, which is the catalyst MO / Ce,V.

[0025] One of the improvements of the present application is to use denitrated manganese oxide as a carrier, combined with a desulfurization catalyst to achieve simultaneous desulfurization and denitrification.

[0026] The improvement of the present application is also that the porous structure of manganese oxide MO provides more loading sites for active components, which can generate more active sites during the reaction process, increase the contact opportunities with pollutants, and improve the reaction efficiency. The three metals have a synergistic effect, which improves the overall desulfurization and denitrification effect of the catalyst. The desulfurization efficiency and denitrification efficiency of the flue gas are more than 85% and 94%, respectively. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 XRD characterization chart of the product

[0028] Figure 2 SEM morphology chart of the product

[0029] EXAMPLE 1

[0030] Step one, dissolve 1.42g manganese acetate and 1.08g terephthalic acid in 30ml DMF respectively. Ultrasonic treatment for 20min, stirring for 30min, then transfer the mixed solution to a 50ml polytetrafluoroethylene reaction kettle, react at 100℃ for 10h, after the reaction is completed, centrifugal collection of precipitate, using deionized water and anhydrous ethanol each washing three times, drying at 80℃ overnight. Finally, a white powder is obtained.

[0031] Step two, place the synthesized white powder in a tube furnace, heat to 300℃ at a rate of 5℃ / min, and keep for 4h. The required black powder, manganese oxide catalyst matrix MO, is obtained.

[0032] Step three, 1.014 g of the manganese oxide catalyst matrix MO was weighed and uniformly dispersed in 10 mL of deionized water, and 0.4592 g of ammonium metavanadate and 0.25 g of oxalic acid were weighed in a molar ratio of 1:1 (the molar ratio of vanadium element to the matrix was 2.5%). It was heated and stirred at 60°C for 3 h until it was fully mixed; the heated and stirred catalyst was dried at 105°C in a vacuum drying oven for 12 h; after the dried catalyst was taken out and ground, it was placed in a dry and clean ceramic crucible and calcined in a muffle furnace for 5 h.

[0033] Step four, 1.014 g of the product prepared in step three was weighed and uniformly dispersed in 10 mL of deionized water, then 0.85 g of Ce(NO3)3·6H2O (the molar ratio of cerium element to the matrix was 2.5%) was added to the dispersion of the powder, and it was ultrasonically treated at room temperature for 30 min and then continuously stirred for 2 h. After standing at room temperature for 30 min, the supernatant was removed. The obtained lower solid precipitate was placed in an oven and dried at 100°C for 12 h. After drying, the sample was ground into powder and placed in a tube furnace and calcined in an air atmosphere at an initial temperature of 20°C, a temperature rising rate of 5°C / min, and a calcination temperature of 300°C for 4 h. After the reaction was completed, the sample was cooled to room temperature to obtain a black powder, which was the desulfurization and denitrification catalyst MO / Ce,V.

[0034]

Example 2

[0035] Step one, 1.42 g of manganese acetate and 1.08 g of terephthalic acid were dissolved in 30 ml of DMF, respectively. After ultrasonic treatment for 20 min and stirring for 30 min, the mixed solution was transferred to a 50 ml polytetrafluoroethylene reaction kettle and reacted at 180°C for 18 h. After the reaction was completed, the precipitate was collected by centrifugation and washed with deionized water and anhydrous ethanol three times each, and then dried at 80°C overnight. Finally, a white powder product was obtained.

[0036] Step two, the synthesized white powder was placed in a tube furnace and heated to 300°C at a temperature rising rate of 5°C / min and kept for 4 h. The desired black powder, manganese oxide catalyst matrix MO, was obtained.

[0037] Step three, 1.014 g of the manganese oxide catalyst matrix MO was weighed and uniformly dispersed in 10 mL of deionized water, and 0.4592 g of ammonium metavanadate and 0.4949 g of oxalic acid were weighed in a molar ratio of 1:1 (the molar ratio of vanadium element to the matrix was 5%). It was heated and stirred at 60°C for 3 h until it was fully mixed; the heated and stirred catalyst was dried at 105°C in a vacuum drying oven for 12 h; after the dried catalyst was taken out and ground, it was placed in a dry and clean ceramic crucible and calcined in a muffle furnace for 5 h.

[0038] Step four, 1.014 g of the product prepared in step three was weighed and uniformly dispersed in 10 mL of deionized water. Then 1.71 g of Ce(N03)3-6H20 was added to the dispersion of the powder (molar ratio of cerium element to the base was 5%) and treated with ultrasound for 30 min at room temperature, followed by continuous stirring for 2 h. After standing for 30 min at room temperature, the supernatant was removed. The obtained lower solid precipitate was placed in an oven and dried at 100 °C for 12 h. After drying, the sample was ground into powder and placed in a tube furnace and calcined in an air atmosphere at an initial temperature of 20 °C, a temperature rising rate of 5 °C / min, and a calcination temperature of 300 °C for 4 h. After the reaction was completed, the sample was cooled to room temperature to obtain a black powder, which was the desulfurization and denitrification catalyst MO / Ce, V.

[0039] Comparative Example 1

[0040] Steps one and two were the same as in Examples 1 and 2.

[0041] Step three, 1.014 g of the manganese oxide catalyst base MO was weighed and uniformly dispersed in 10 mL of deionized water. 0.4592 g of ammonium metavanadate and 0.4949 g of oxalic acid were added (molar ratio of vanadium element to the base was 5%) at a ratio of 1:1. The mixture was heated and stirred at 60 °C for 3 h until it was fully mixed. The heated and stirred catalyst was dried in a vacuum drying oven at a constant temperature of 105 °C for 12 h. After drying, the catalyst was taken out and ground, and then placed in a dry and clean ceramic crucible and calcined in a muffle furnace for 5 h to obtain the product catalyst MO / V.

[0042] Comparative Example 2

[0043] Steps one and two were the same as in Examples 1 and 2.

[0044] Step three, 1.014 g of the product prepared in step two was weighed and uniformly dispersed in 10 mL of deionized water. Then 1.71 g of Ce(N03)3-6H20 was added to the dispersion of the powder (molar ratio of cerium element to the base was 5%) and treated with ultrasound for 30 min at room temperature, followed by continuous stirring for 2 h. After standing for 30 min at room temperature, the supernatant was removed. The obtained lower solid precipitate was placed in an oven and dried at 100 °C for 12 h. After drying, the sample was ground into powder and placed in a tube furnace and calcined in an air atmosphere at an initial temperature of 20 °C, a temperature rising rate of 5 °C / min, and a calcination temperature of 300 °C for 4 h. After the reaction was completed, the sample was cooled to room temperature to obtain a black powder, which was the product catalyst MO / Ce.

[0045] Comparative Example 3

[0046] Steps one and two were the same as in Examples 1 and 2.

[0047] Step three, 1.014 g of manganese oxide catalyst matrix is weighed and uniformly dispersed in 10 mL of deionized water, and 0.4592 g of ammonium metavanadate and 0.4949 g of oxalic acid, 1.71 g of Ce(NO3)3·6H2O are weighed in a molar ratio of 1:1:1. Stir at 60℃ for 3h until fully mixed; the heated and stirred catalyst is dried in a vacuum drying oven at 105℃ for 12 hours; after drying, the catalyst is taken out and ground, and then placed in a dry and clean ceramic crucible and calcined in a muffle furnace for 5h.

[0048] Effect detection:

[0049] Figure 1 The XRD pattern of the product is shown in the figure. As can be seen from the figure, the XRD pattern of the manganese metal organic framework derived MnO appears at 18.3°, 29.2°, 32.7°, 36.4°, 44.7°, 51.1°, 60.2°, etc. After consulting relevant data analysis, it can be obtained that it corresponds to the characteristic diffraction peak of Mn3O4 (JCPDS 24-0734). The diffraction peaks appearing at 23.0°, 32.8°, 38.1°, 45.2°, 49.2°, 55.0°, 67.4° can well correspond to the characteristic diffraction peaks of the standard Mn2O3 sample (JCPDS 41-1442). 28.549°, 33.083°, 46.486°, 56.346°, 59.093° are weak diffraction peak patterns of CeO2, and 26.759°, 34.742°, 36.23°, 41.289 are weak diffraction peak patterns of V2O5. Therefore, it can be shown that the manganese oxide catalyst mainly exists in the form of Mn3O4 and Mn2O3, and a small amount of CeO2 and V2O5.

[0050] Figure 2 The SEM image of the product is shown in the figure. As can be seen from the figure, the surface of the matrix is a porous structure with high porosity, and a large number of particles are loaded in the voids of the matrix. The small particles are CeO2 and V2O5 particles, and the large particles are Mn3O4 and Mn2O3 particles. Figure 1 and 2 It can be seen that the catalyst realizes effective loading of vanadium oxide and cerium oxide. The specific surface area of the catalyst is 65.1m 2 / g, and the porosity is 0.52cm 3 / g.

[0051] For the catalytic effect, the obtained product catalyst is subjected to flue gas containing NO and SO2, and is catalyzed at 260℃ for 8h, and the conversion rate is measured. The results are as follows.

[0052]

[0053]

[0054] After the reaction, the gas is detected by a flue gas analyzer, and NO2 is detected in the gas product after the denitration experiment, indicating that the catalytic reaction oxidizes NO to NO2;After the desulfurization experiment, the gas is passed into the HCl+BaCl2 solution, and after a period of time, white precipitate is produced. It is shown that through catalytic reaction, SO2 is oxidized to SO3, and the generated SO3 reacts with BaCl2 solution to generate BaSO4 precipitate.

[0055] The application selects CeO2 and V2O5 to react to form CeVO4 with higher oxidation activity, which can further promote the oxidation process of SO2 to SO3 and improve the desulfurization efficiency. The main active component of the denitration reaction is MnOx, because this metal oxide has good oxidation activity and can oxidize NO to higher valence NOx. When the CeO2 additive is added, the cerium oxide keeps the internal lattice of the catalyst stable at a higher calcination temperature, prevents the crystal form from changing to other directions, and makes the crystal grains remain in a fine state, which also allows more active sites to be retained. The synergistic effect between vanadium and manganese mainly occurs during the co-impregnation process, and vanadium and manganese form V-O-Mn bonds. During the reaction, the high-activity MnVOx will undergo oxidation reaction to finally generate Mn(I)V (4+) O x-1 Moreover, in the presence of manganese, the reduction of vanadium can be promoted, and the overall desulfurization and denitration effect of the catalyst can be improved. The regeneration ability of Mn is improved, thereby promoting the denitration of the catalyst, and finally improving the catalytic efficiency of simultaneous desulfurization and denitration.

[0056] Although the application has been described with reference to the exemplary embodiments thereof, it should be understood that modifications and variations can be made by those skilled in the art, which would fall within the principles and spirit of the application disclosed herein. More specifically, variations and modifications to the subject combination layout, its component parts, and / or layout can be made within the scope and spirit of the disclosure and the claims. Other uses will also become apparent to those skilled in the art, in addition to modifications and improvements to the component parts and / or layout.

Claims

1. A method for producing a desulfurization and denitration porous catalyst, characterized by, The method comprises, Preparation of the porous manganese oxide MO matrix: a manganese source and terephthalic acid are dissolved in a solvent, then solvent thermal reaction is carried out in a high-pressure reaction kettle, and the product is separated and then calcined in a high-temperature furnace; Loading of the porous manganese oxide MO matrix: the loading method is to disperse the calcined product in a vanadium salt solution, heat and stir, and then calcine; the calcined product is dispersed in a cerium salt solution, microwave ultrasonic reaction is carried out, and then calcination is carried out to obtain the catalyst; The manganese source is selected from manganese nitrate, manganese chloride and manganese acetate; and the solvent is selected from DMF, ethanol and methanol; The solvent thermal temperature is 100-180℃, and the solvent thermal time is 10-18h; The molar ratio of the manganese source to terephthalic acid is 1:2-2:1; The catalyst is a porous manganese oxide MO matrix loaded with V2O5 and CeO2, the manganese oxide mainly exists in the form of Mn3O4 and Mn2O3, the molar content of V2O5 and CeO2 relative to the porous manganese oxide MO is 0.01-0.05 and 0.01-0.05, the porous manganese oxide matrix is a honeycomb-like porous structure, and the V2O5 and CeO2 are loaded on the surface of the porous manganese oxide; The specific surface area of the catalyst is 65.1 m 2 / g, the porosity is 0.52 cm 3 / g.

2. The method for preparing a desulfurization and denitrification porous catalyst according to claim 1, characterized in that, The vanadium salt solution is a mixed solution of ammonium metavanadate and oxalic acid, and the molar ratio of the two is 1:1; the heating and stirring conditions are 60℃ temperature heating and stirring for 3h.

3. The method for preparing a desulfurization and denitrification porous catalyst according to claim 1, characterized in that, The calcination and calcination process conditions are the same, and both are 5℃ / min heating rate to 300℃, and heat preservation for 4h.

4. Application of the catalyst obtained by the preparation method of the desulfurization and denitrification porous catalyst according to any one of claims 1-3 in flue gas desulfurization and denitrification conversion.

Images