[0027] According to the preparation method of the catalyst for de-dioxin synergistic denitration provided by the present invention, the preparation method comprises the following steps:
[0028] Step 1. To 10-15 parts by weight of lanthanum salt, 5-8 parts by weight of strontium salt, 5-8 parts by weight of neodymium salt, 10-15 parts by weight of manganese salt, 5-8 parts by weight of chromium salt and 5 Add 18-25 parts by weight of water to 8 parts by weight of iron salt, heat to 40-60 ° C, stir until completely dissolved, then add 20-30 parts by weight of silicon oxide and 4-8 parts by weight of activated carbon powder, mix Evenly into the first mud;
[0029] Step 2, extruding the first mud material, drying at 20-60°C for 4-6 days, roasting at 500-550°C for 1 day, and then pulverizing to make porous powder;
[0030] Step 3, in 4-7 parts by weight of ammonium paramolybdate, 12-18 parts by weight of ammonium metavanadate, 2-5 parts by weight of cobalt salt, 1-3 parts by weight of antimony salt, 6-10 parts by weight Add 6-9 parts by weight of ammonia water with a mass concentration of 15-25% to the cerium salt and 2-4 parts by weight of europium salt and mix well, and then add 28-35 parts by weight of water at 80-90 ° C until completely dissolve into the first solution;
[0031] Step 4, stirring and mixing 50-60 parts by weight of nano-titanium dioxide, 10-15 parts by weight of micro-carbon ferrochrome powder, 20-27 parts by weight of water and 6-8 parts by weight of ammonia water with a mass concentration of 15-25% uniformly obtain the second mixture;
[0032] Step 5. Add the first solution into the second mixture, stir evenly, then add the porous powder obtained in step 2, and then add 8-13 parts by weight of glass fiber filaments, 1.6-2.6 parts by weight of polymer Ethylene oxide, 1.0-1.7 parts by weight of carboxymethyl cellulose, stirred and made into the second mud;
[0033] Step 6. After aging for 40-60 hours, the second mud is extruded into honeycomb or granular shape, dried at 20-70°C for 10-15 days, and roasted at 480-550°C for 2-3 days , that is, the catalyst for the synergistic denitration of dioxins is obtained.
[0034]In step 1, the silicon oxide is nano-state silicon oxide, the size of the nano-grain is 10-20 nm, and the activated carbon powder is 2000 mesh powder.
[0035] In step 4, the nano-titanium dioxide is anatase type titanium dioxide, the size of the nano-grain is 8-15nm, and the specific surface area is 90-120m 2 /g; the composition requirements of micro-carbon ferrochromium powder are C≤0.1%, Cr≥60%, Fe balance, and the particle size of the powder is 1500-2000 mesh.
[0036] In step 5, the fiber diameter of the glass fiber is 3-5 μm, the length is 1-3 mm, and the dispersion degree is more than 90%; 50000.
[0037] In the above method, lanthanum, strontium, neodymium, chromium, iron, cobalt, cerium and europium salts are preferably nitrates, manganese salts are preferably manganese acetate, and antimony salts are preferably antimony chloride. These salts can be dissolved in water to form an ionic state, which is conducive to bond-forming compounds, thereby forming a cross-linked structure.
[0038] After the extrusion molding, drying, roasting and pulverizing steps of step 2, the ultra-fine porous powder is obtained. Wherein, the pulverizing step can be carried out by cutting mill or jet mill. The particle size of the obtained ultra-fine porous powder is preferably 800-1500 mesh.
[0039] In the production method of the present invention, the water used in each step is preferably pure water.
[0040] In the catalyst preparation method for de-dioxin synergistic denitration of the present invention, in order to improve the dispersibility of the active components and improve the interaction effect between the active components and the carrier, the amount of water added is in an excess state, and usually In step 5, the moisture content is adjusted by the action of heat and moisture removal, so as to obtain uniform mud with suitable hardness and softness.
[0041] The catalyst for synergistic denitrification of dioxins according to the present invention includes a carrier, as well as porous powder and transition metal oxide catalytically active parts dispersed in the carrier.
[0042] The above-mentioned porous powder has a perovskite structure, wherein lanthanum nitrate, strontium nitrate, and neodymium nitrate are dissolved in each other to form a substance in the A position in the perovskite structure, and manganese acetate, chromium nitrate, and iron nitrate are dissolved in each other to form B in the perovskite structure. bit substance. Therefore, the perovskite structure can be used with the structural formula ABO 3 Expression: (La, Sr, Nd) (Mn, Cr, Fe)O 3. In the element combination of the present invention, both the ability to remove dioxins and the effect of denitration are considered, and the electronegativities of lanthanum (La), strontium (Sr), and neodymium (Nd) at the A site are 1.10, 0.95, 1.14, easy to lose electrons, showing good reducibility, which is favorable for selective catalytic reduction (SCR) denitration reaction; while manganese (Mn), chromium (Cr), iron (Fe) on the B site are negatively charged The properties were 1.55, 1.66, and 1.83, respectively, with a strong ability to capture electrons, which was beneficial for selective catalytic oxidation (SCO) dedioxinization. The perovskite structure of this ratio has a large number of surface active oxygen species, so it has high catalytic activity and can remove the chlorine atoms adsorbed on the surface of the catalyst. At the same time, the water vapor in the flue gas can also quickly remove the surface of the perovskite catalyst. Adsorbed chlorine atoms, which is beneficial to improve the anti-chlorine and hydrogen chloride poisoning ability of the catalyst. In order to improve the dispersive porosity of the above-mentioned perovskite minerals in the catalyst, nano-silica and activated carbon powder are added and mixed evenly, and then the ultra-fine powder is made by extruding, drying, roasting and grinding. During the roasting process, the activated carbon particles are oxidized to CO, CO 2 escape and form abundant pore-volume pores, which can significantly enhance resistance to oxygen, ammonia, dioxin, NO x The adsorption effect of other substances improves the contact opportunity and reaction efficiency of active elements and removed substances.
[0043] The catalytically active part of the transition metal oxide includes main active elements and auxiliary active elements, wherein the main active elements include vanadium, cobalt, chromium and iron, and the auxiliary active elements include molybdenum, antimony, cerium and europium.
[0044] Specifically, ammonium paramolybdate, ammonium metavanadate, cobalt salts (such as cobalt nitrate), antimony salts (such as antimony chloride), cerium salts (such as cerium nitrate), europium salts (such as europium nitrate) are mutually dissolved and passed through The main active elements vanadium, cobalt, chromium, iron, and the auxiliary active elements molybdenum, antimony, cerium, and europium are formed after mixing and roasting with nano-titanium dioxide, micro-carbon ferrochromium, etc.
[0045] In the above-mentioned transition metal oxide catalytically active part, the main active element and the auxiliary active element form a compound structure with good SCO reaction and SCR reaction selectivity at the same time. Cerium and europium have rich valence structures and good oxygen storage and supply capabilities, which are helpful for simultaneous SCO dedioxin and SCR denitration. The strong oxidizing properties of molybdenum and antimony compounds can promote the SCO reaction of dioxin removal. They have strong anti-chlorine, hydrogen chloride and hydrogen sulfide poisoning ability, but have little effect on the SCR denitration reaction with ammonia as a reducing agent. Vanadium, cobalt, chromium, iron compounds to NO x The reducing ability of dioxin is good, and because its electronegativity is at a moderate level, it also has a certain promoting effect on the SCO reaction of dioxin.
[0046] The catalytically active part of the above-mentioned perovskite structure is added to the final slurry for preparing the catalyst in the form of prefabricated ultra-fine porous powder, which has two characteristic effects: 1) It can prevent the perovskite structure from being interfered by other elements. Corresponding performance; 2) If a large amount of active substances are added in the form of nitrate, sulfate or chloride, a large amount of gas will be decomposed during the preparation process, which makes the production process very difficult, and the yield Low, the strength and wear resistance of the product will be low. The above problems can be avoided by preparing the porous powder by prefabricating the method of the present invention.
[0047] The purpose of adding micro-carbon ferrochromium powder to the components is: the surface of the ultra-fine micro-carbon ferrochromium powder particles is easy to form an oxidation state during the calcination process, and the Cr-Fe solid solution becomes a compound structure of chromium oxide and iron oxide after oxidation ( Cr,Fe)O x , its compound uniformity exceeds the effect of adding chromium nitrate and ferric nitrate. In the present invention, considering the improvement of catalyst activity and service life, a large amount of addition is required. If it is not feasible to add a large amount of chromium nitrate and ferric nitrate, it is easy to generate a large amount of NO during the calcination process. x , which affects the catalyst strength and wear resistance when escaping.
[0048] The micro-carbon ferrochromium powder used in the present invention requires C≤0.1%. If the carbon content is too high, it is easy to form chromium carbide and iron carbide, which hinders the formation of chromium oxide and iron oxide, and a large amount of CO is formed after carbon oxidation. 2 and CO, which affect the strength of the catalyst when escaping, and affect dioxin, ammonia, oxygen, NO when left in the catalyst x Wait for the adsorption on the active site to form a competitive relationship, resulting in dioxin and NO x The decomposition effect is reduced.
[0049] Since the present invention adopts the structure of dual-active system, many active components are added, so the prepared cement body is required to undergo sufficient aging time, so that each component can be fully infiltrated and reacted to obtain the designed components. The drying and roasting process adopts a long time and slow heating method, so that the decomposed gaseous substances can be slowly and fully precipitated, reducing the influence on the structural composition, strength and wear resistance of the catalyst, making the catalyst structure richer, more stable and more stable. Reliability is improved.
[0050] In the preparation process of the catalyst for synergistic denitrification of dioxins, in order to improve the dispersibility of active components and improve the interaction effect between active components and the carrier, the amount of pure water added is in an excess state, and the moisture is removed by heat. Function to adjust the moisture content, so that the mud can achieve good extrusion process effect.
[0051] In addition, the dedioxin synergistic denitration catalyst of the present invention also includes glass fiber filaments, preferably glass fiber filaments with a diameter of 3-5 μm and a length of 1-3 mm, and the required degree of dispersion is more than 90%. Glass fiber filaments with small diameters are relatively soft, are not easily broken during the mixing process, and will not be powdered. They are shorter in length and better in dispersion, which is conducive to the preparation of honeycomb catalysts with 30-50 pores. Usually, the dioxin removal catalyst is arranged after the dust collector, and selecting a dense pore structure can increase the surface area of the catalyst and reduce the catalyst dosage and construction cost.
[0052] The dedioxin synergistic denitration catalyst according to the present invention is a selective catalytic oxidation/reduction type catalyst, wherein the perovskite type catalytic active part has good catalytic stability, and has a certain degree of dedioxin removal at higher temperatures. Catalytic activity and certain denitration catalytic ability, the catalytically active part of transition metal oxides has strong resistance to chlorine, hydrogen chloride, hydrogen sulfide, sulfur oxide, ammonium sulfate, water, and alkali (alkaline earth) metals, and has a higher resistance at lower temperatures. High dedioxin activity and certain denitration catalytic activity, through the combined structure of the dual active system of the transition metal composite oxide catalytic active part and the perovskite catalytic active part, the dedioxin from low temperature to high temperature can be achieved. The excellent performance of synergistic denitrification, and the anti-poisoning ability is obviously improved.
[0053] The present invention is further illustrated by the following examples, but the scope of the present invention is not limited to the following examples.
