Method for synthesizing high-performance rare earth-titanium-based superfine composite oxide
阅读说明：本技术 一种合成高性能稀土-钛基超细复合氧化物的方法 (Method for synthesizing high-performance rare earth-titanium-based superfine composite oxide ) 是由 陈勇 刘雪松 冯淼 胡波 沈毅 王耀光 李景慧 周浩平 俞奇开 于 2020-12-21 设计创作，主要内容包括：本发明公开了一种合成高性能稀土-钛基超细复合氧化物的方法,包括如下步骤：首先,将铈的硝酸盐和钛的硫酸盐溶于水和四氢呋喃配成混合溶液；然后,加入添加元素的可溶盐溶液和无机硅酸盐,利用沉淀剂将pH调至8-10,继续搅拌0.5-1.5h后,真空低温干燥去除水得到铈-钛基复合氧化；最后,在二氧化硫-氮气混合气氛600-800℃焙烧1-2h,然后纯氧气中300-500℃焙烧2-3h,制得的高性能铈-钛基超细复合氧化物。本发明添加Pr、La、Nd、Y等稀土元素来提高CeO-2的氧缺位浓度,可获得比钒钨钛催化剂更多的表面活性氧物种,从而提高催化剂低温脱硝性能。(The invention discloses a method for synthesizing high-performance rare earth-titanium-based superfine composite oxide, which comprises the following steps: firstly, dissolving nitrate of cerium and sulfate of titanium in water and tetrahydrofuran to prepare a mixed solution; then adding soluble salt solution added with elements and inorganic silicate, adjusting the pH to 8-10 by using a precipitator, continuously stirring for 0.5-1.5h, and drying at low temperature in vacuum to remove water to obtain cerium-titanium-based composite oxide; finally, roasting for 1-2h at 800 ℃ in a mixed atmosphere of sulfur dioxide and nitrogen at 600 ℃ and then roasting for 2-3h at 500 ℃ in pure oxygen to obtain the high-performance cerium-titanium-based superfine composite oxide. The invention adds rare earth elements such as Pr, La, Nd, Y and the like to improve CeO 2 The oxygen vacancy concentration can obtain more surface active oxygen species than the vanadium tungsten titanium catalyst, thereby improving the low-temperature denitration of the catalystAnd (4) performance.)
1. A method for synthesizing high-performance rare earth-titanium-based superfine composite oxide is characterized by comprising the following steps:
firstly, dissolving nitrate of cerium and sulfate of titanium in water and tetrahydrofuran to prepare a mixed solution, wherein the molar weight of Ce, the molar weight of Ti, the molar weight of tetrahydrofuran and the molar weight of water are 1:10:80:100-1:1:8: 10;
then adding an additive element soluble salt solution and inorganic silicate, adjusting the pH to 8-10 by using a precipitator, continuously stirring for 0.5-1.5h, and drying at low temperature in vacuum to remove water to obtain cerium-titanium-based composite oxide;
finally, roasting for 1-2h at 800 ℃ in a mixed atmosphere of sulfur dioxide and nitrogen at 600 ℃ and then roasting for 2-3h at 500 ℃ in pure oxygen to obtain the high-performance cerium-titanium-based superfine composite oxide.
2. The method for synthesizing high performance rare earth-titanium based ultrafine composite oxide according to claim 1, wherein: the additive element is one or more than two of soluble salts of Pr, La, Nd and Y.
3. The method for synthesizing high performance rare earth-titanium based ultrafine composite oxide according to claim 1, wherein: the inorganic silicate is one or more than two of fly ash, montmorillonite, attapulgite and Hangjin second soil.
4. The method for synthesizing high performance rare earth-titanium based ultrafine composite oxide according to claim 1, wherein: the precipitant is one or more than two of ammonia water, urea solution and ammonium carbonate.
Technical Field
The invention belongs to the field of synthesis of cerium-titanium-based superfine composite oxides, and particularly relates to a preparation method of a high-performance cerium-titanium-based superfine composite oxide for coating a ceramic fiber pipe.
Background
NH3SCR is currently recognized as an ideal denitration technology, where the catalyst is the core of the technology. At present, commercial denitration catalysts are mainly vanadium-tungsten-titanium, have the advantages of strong sulfur poisoning resistance, low cost and the like, and are widely applied to the field of denitration of thermal power plants. The vanadium-tungsten-titanium catalyst is prepared by adopting a traditional coprecipitation method to prepare TiO2The carrier is then loaded with V by an impregnation method2O5And WO3And finally, the rotary kiln is utilized to carry out conventional air drying and calcining, and the process has the defects of complex synthesis process, serious environmental pollution, high energy consumption and the like. And the particle size and specific surface area of the obtained product are respectively 10 micrometers and 80m2In terms of/g, it is therefore only suitable for the production of monolithic extruded honeycomb catalysts. In addition, the vanadium-tungsten-titanium catalyst has the defects of poor low-temperature activity, toxic active substances and the like, and can not meet the requirement of non-thermal power denitration.
Ceramic fiber filtration technology is one of the more rapidly developing filtration technologies in recent years. Compared with the traditional granular filter material, the specific surface area of the fiber filter material is large. The interface adsorption capacity is strong, the suspended matters can be throttled, and the filtering effect is good. The high-temperature composite filter cylinder product technology is suitable for high-temperature flue gas, can simultaneously perform integrated dust removal and denitration, has good treatment effect, simplifies the process flow, is favorable for improving the subsequent heat energy conversion efficiency, prolongs the service life of the system, is favorable for improving the situations of unsatisfactory treatment effect of waste gas pollutants in the non-electric industry and unstable operation of the device, and is an advanced environment-friendly technology worthy of popularization. But the production technology of the catalyst suitable for the high-temperature composite filter cylinder and the ceramic fiber filter tube is always mastered by foreign enterprises.
Therefore, the method has great significance in designing the high-efficiency rare earth catalyst based on domestic resources and developing a novel preparation method matched with the high-efficiency rare earth catalyst to meet the requirement of non-thermal power flue gas denitration and simultaneously reducing vanadium pollution.
Disclosure of Invention
The invention aims to solve the technical problem of providing a preparation method of a cerium-titanium-based superfine composite oxide for coating a ceramic fiber pipe, and overcoming the defects of low-temperature denitration performance, large granularity, complex synthesis process and high cost of the existing cerium-titanium-based superfine composite oxide.
In order to solve the technical problems, the invention adopts the following technical scheme: a method for synthesizing high-performance rare earth-titanium-based superfine composite oxide comprises the following steps:
firstly, dissolving nitrate of cerium and sulfate of titanium in water and tetrahydrofuran to prepare a mixed solution, wherein the molar weight of Ce, the molar weight of Ti, the molar weight of tetrahydrofuran and the molar weight of water are 1:10:80:100-1:1:8: 10;
then adding soluble salt solution added with elements and inorganic silicate, adjusting the pH to 8-10 by using a precipitator, continuously stirring for 0.5-1.5h, and drying at low temperature in vacuum to remove water to obtain cerium-titanium-based composite oxide;
finally, roasting for 1-2h at 800 ℃ in a mixed atmosphere of sulfur dioxide and nitrogen at 600 ℃ and then roasting for 2-3h at 500 ℃ in pure oxygen to obtain the high-performance cerium-titanium-based superfine composite oxide.
Preferably, the additive element is one or more of soluble salts of Pr, La, Nd and Y.
Preferably, the inorganic silicate is one or more than two of fly ash, montmorillonite, attapulgite and Hangjin second soil.
Preferably, the precipitant is one or more of ammonia water, urea solution and ammonium carbonate.
Compared with the prior art, the technical scheme adopted by the invention has the following characteristics:
1. the invention adopts water and tetrahydrofuran as solvents, can reduce the hydrolysis speed compared with the traditional water system, and is beneficial to obtaining the ultrafine powder oxide with small particles.
2. The invention adds rare earth elements such as Pr, La, Nd, Y and the like to improve CeO2The oxygen vacancy concentration of the catalyst can obtain more surface active oxygen species than vanadium tungsten titanium catalyst, thereby improving the low-temperature denitration performance of the catalyst.
3. The invention adds low-cost inorganic silicate to improve the thermal stability and the acid site number of the catalyst, and the addition of the silicate can inhibit the TiO2Agglomeration in the sintering process, thereby obtaining the specific surface area higher than that of vanadium, tungsten and titanium. In addition, the increase in the number of acid sites of the catalyst is also beneficial to improving the activity of ammonia species activation and denitration.
4. The invention adopts low-temperature vacuum drying to reduce the damage of the drying process to the catalyst structure, and simultaneously adopts two-stage calcination of nitrogen and oxygen to obviously reduce the catalyst structure collapse and the active site loss caused by high temperature.
5. In the invention, SO is used2The effective active acid sites on the surface of the catalyst can be effectively increased by atmosphere pretreatment, so that the denitration activity is improved.
6. The preparation method has the advantages of simple process, low equipment requirement and low cost.
The invention is based on the characteristics that the obtained composite oxide has the following advantages:
1. the specific surface area of the cerium-titanium-based superfine composite oxide is more than 200m2And the denitration efficiency at 150 ℃ is more than 90 percent.
2. The cerium-titanium-based superfine composite oxide has high thermal stability and aging at 550 DEG CAfter the reaction for 10 hours, the specific surface area is more than 150m2/g。
3. Particle size D of the cerium-titanium-based ultrafine composite oxide of the invention90<0.1 micron.
The following detailed description will explain the present invention and its advantages.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A method for synthesizing high-performance rare earth-titanium-based superfine composite oxide comprises the following steps:
firstly, dissolving nitrate of cerium and sulfate of titanium in water and tetrahydrofuran to prepare a mixed solution, wherein the molar weight of Ce, the molar weight of Ti, the molar weight of tetrahydrofuran and the molar weight of water are 1:10:80:100-1:1:8: 10;
then adding soluble salt solution added with elements and inorganic silicate, adjusting the pH to 8-10 by using a precipitator, continuously stirring for 0.5-1.5h, and drying at low temperature in vacuum to remove water to obtain cerium-titanium-based composite oxide;
finally, roasting for 1-2h at 800 ℃ in a mixed atmosphere of sulfur dioxide and nitrogen at 600 ℃ and then roasting for 2-3h at 500 ℃ in pure oxygen to obtain the high-performance cerium-titanium-based superfine composite oxide.
Wherein the additive element is one or more than two of soluble salts of Pr, La, Nd and Y. The inorganic silicate is one or more than two of fly ash, montmorillonite, attapulgite and Hangjin second soil. The precipitant is one or more than two of ammonia water, urea solution and ammonium carbonate.
Example 1
Dissolving nitrate of cerium and sulfate of titanium in water and tetrahydrofuran to prepare a mixed solution, wherein the molar weight of Ce is Ti molar weight, the molar weight of tetrahydrofuran is 2:9:85: 90;
then adding yttrium nitrate solution and montmorillonite, adjusting pH to 9 by using a precipitator, ensuring that the final molar ratio of cerium, titanium, yttrium and montmorillonite is 4:5:1:1, continuously stirring for 1h, and drying in vacuum at 80 ℃ to remove water to obtain cerium-titanium-based composite oxide; finally, roasting the mixture for 2 hours at 700 ℃ in a mixed atmosphere of sulfur dioxide and nitrogen, and then roasting the mixture for 2 hours at 400 ℃ in pure oxygen to obtain the cerium-titanium-based superfine composite oxide with the specific surface area of 240m2The denitration efficiency at 150 ℃ is 93 percent, and the specific surface area is 182m after aging at 550 ℃ for 10h2/g。
Example 2
The difference from the example 1 is that the added elements are La and Nd, the inorganic silicate is Hangjin No. two soil, and the final molar ratio of cerium to titanium to the added elements La + Nd to the Hangjin No. two soil is 4:6:1: 1. Stirring for 0.5h, and vacuum drying at 70 ℃ to remove water to obtain cerium-titanium-based composite oxide; finally, roasting for 1h at 600 ℃ in a mixed atmosphere of sulfur dioxide and nitrogen, and then roasting for 3h at 500 ℃ in pure oxygen to obtain the cerium-titanium-based superfine composite oxide with the specific surface area of 230m2The denitration efficiency at 150 ℃ is 91%, and the specific surface area is 175m after aging at 550 ℃ for 10h2/g。
Example 3
The difference from the embodiment 2 is that the precipitator is a mixed solution of ammonia water and urea, the mixture is stirred for 2 hours, and the cerium-titanium-based composite oxide is obtained by vacuum drying at 60 ℃ to remove water; finally, roasting for 1h at 600 ℃ in a mixed atmosphere of sulfur dioxide and nitrogen, and then roasting for 3h at 500 ℃ in pure oxygen to obtain the cerium-titanium-based superfine composite oxide with the specific surface area of 250m2The denitration efficiency at 150 ℃ is 94 percent, and the specific surface area is 188m after aging at 550 ℃ for 10h2/g。
Example 4
In order to prepare vanadium-tungsten-titanium series catalysts for comparative study, ammonium metavanadate and titanium sulfate are dissolved in water to prepare a solution with a certain concentration, and a certain amount of ammonium metatungstate solution and ammonia water are dripped togetherAdd to pH 9 and ensure a final vanadium to titanium to tungsten molar ratio of 4:5: 1. Stirring for 1h, and spray-drying at 80 ℃ to remove water; roasting at 700 ℃ for 1h in nitrogen atmosphere, and finally roasting at 400 ℃ for 4h in air atmosphere to obtain the vanadium-titanium base superfine composite oxide with the specific surface area of 40m2The denitration efficiency is 4 percent at the temperature of 150 ℃ and the specific surface area is 12m after aging for 10 hours at the temperature of 550 DEG C2/g。
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that the invention is not limited thereto, and may be embodied in other forms without departing from the spirit or essential characteristics thereof. Any modification which does not depart from the functional and structural principles of the present invention is intended to be included within the scope of the claims.