阅读说明：本技术 一种利用天然矿土和废渣制备脱汞催化剂的方法 (Method for preparing demercuration catalyst by using natural ore soil and waste residues ) 是由 徐书敏 于 2019-11-25 设计创作，主要内容包括：本发明涉及一种利用天然矿土和废渣制备氧化脱汞催化剂的方法,属于废物综合利用和气体净化领域。本发明制备的催化剂有效利用了赤泥中含有的Fe、Al、Ti等金属和碱,使其同时对蒙脱石进行柱撑改性和负载,后与污泥进行混合炭化,形成多孔结构。制备的催化剂具有孔隙率高、比表面积大、金属固载稳定的优势,其比表面积可达178m<Sup>2</Sup>/g,孔体积可达0.49m<Sup>3</Sup>/g,将其应用于烟气脱汞,能够在较低温度下实现Hg<Sup>0</Sup>的高效氧化。本发明的制备工艺简单,条件温和,所用原料为天然矿土和工业废弃物,成本低廉,并能够解决上述废渣的囤积和环境污染问题,具有广泛的应用前景。(The invention relates to a method for preparing an oxidation demercuration catalyst by utilizing natural ore soil and waste residues, belonging to the field of comprehensive utilization of waste and gas purification. The catalyst prepared by the invention effectively utilizes metals such as Fe, Al, Ti and the like and alkali contained in the red mud, so that the red mud can simultaneously carry out pillared modification and loading on the montmorillonite, and then is mixed and carbonized with the sludge to form a porous structure. The prepared catalyst has the advantages of high porosity, large specific surface area and stable metal immobilization, and the specific surface area can reach 178m 2 Per g, pore volume up to 0.49m 3 The mercury removal catalyst is applied to flue gas mercury removal, and can realize Hg at a lower temperature 0 High efficiency oxidation. The preparation process is simple, and the conditions are mildThe raw materials are natural ore soil and industrial wastes, the cost is low, the problems of accumulation of the waste residues and environmental pollution can be solved, and the method has wide application prospect.)

1. A method for preparing a demercuration catalyst by using natural ore soil and waste residue is characterized by comprising the following steps:

(1) adding red mud into water with the volume 2-5 times that of the red mud, continuously stirring, filtering, collecting filtrate, and recovering alkali in the red mud, wherein the filtrate is recorded as s 1; adding 0.1-0.8mol/L hydrochloric acid into the obtained red mud, adding acid, and stirring for 0.5-2h to dissolve partial metal Al and Fe in the red mud, wherein the liquid-solid ratio L/S =2-10mL/g, and the obtained suspension is marked as S2;

(2) slowly adding the filtrate S1 into the suspension S2 under continuous stirring, adding the amount of liquid-solid ratio L/S =2-5mL/g, continuously adding water with the volume of 15-20 times that of the filtrate S1, stirring for 1-3h, standing and aging to ensure that dissolved Al and Fe form hydroxyl compounds, and recording the obtained suspension as S3;

(3) adding dried montmorillonite into the suspension s3, wherein the adding amount is 0.5-2 times of the mass of the solid in the suspension, continuously stirring to ensure that hydroxy iron aluminum carries out pillared modification on the montmorillonite, standing for aging, filtering, washing and drying to obtain a mixture of red mud and pillared montmorillonite;

(4) and mixing the mixture of the red mud and the pillared montmorillonite with 10-20wt% of dehydrated dry sludge, roasting and carbonizing at 900 ℃ for 5-10h under a nitrogen atmosphere, and continuously roasting at 500 ℃ for 2-6h under an air atmosphere at 300-.

2. The method according to claim 1, wherein the red mud is bayer process red mud, in mass fraction, Al₂O₃Content (wt.)5-20 wt.% of Fe₂O₃The content is 5-35 wt%.

3. The method of claim 1, wherein the montmorillonite is acid pretreated montmorillonite.

4. The process according to claim 1, wherein the aging in steps (2) and (3) is carried out at room temperature for a period of 6 to 10 hours.

Technical Field

The invention relates to a method for preparing an oxidation demercuration catalyst by utilizing natural ore soil and waste residues, belonging to the field of comprehensive utilization of waste and gas purification.

Background

The coal as the most main energy occupies more than 70% of the energy structure in China, and the coal consumed in China every year occupies 31% of the total consumption of raw coal in the world. However, the average mercury content in the coal in China is 0.22mg/kg, which is far higher than the world average mercury content of 0.13 mg/kg. The amount of mercury discharged to the atmosphere in China every year due to coal-fired power stations is 500-700 t, and accounts for about 30% of the total emission amount of the world. Therefore, how to effectively control mercury in coal-fired flue gas has become an urgent problem to be solved.

The catalytic oxidation demercuration technology is to remove Hg in flue gas⁰Oxidation to easily removed Hg²⁺The technique of (1). At present, the methodThe research on the mercury catalytic oxidation technology is mainly about the development of catalysts, and the catalysts can be divided into three categories: SCR catalyst, catalyst using carbon as carrier to load metal, metal and its oxide. The catalysts all adopt pure chemical reagents as raw materials, the preparation cost is high, and how to develop the catalyst which is low in price and can ensure high catalytic oxidation efficiency becomes the key point of research.

Montmorillonite is a common natural mineral, and in recent years, part of scholars adopt modified montmorillonite for mercury removal. CN105664838A discloses a mercury removal adsorbent of metal oxide-loaded pillared montmorillonite, which has high thermal stability, high mercury removal efficiency, low cost, environmental friendliness and great application potential through the synergistic effect between pillared montmorillonite and active components. The research institute of process engineering of Chinese academy of sciences also uses the montmorillonite loaded with manganese for the catalytic oxidation of elemental mercury in flue gas, and the result shows that 4% Mn/montmorillonite shows good mercury removal efficiency and has potential industrial application value (research on the catalytic oxidation of elemental mercury by montmorillonite-loaded manganese catalyst, Wu Ying hong, Chinese outstanding Master thesis). Therefore, the combination of the montmorillonite and the metal oxide can effectively adsorb and catalyze and oxidize Hg in the smoke. The red mud is Al produced in bauxite industry₂O₃The strong alkaline solid residue generated in the process and the waste alkali liquor in the red mud can cause soil alkalization, swampiness and pollution to surface and underground water sources, and directly harm human health. China is the world with the highest output of alumina and red mud, and in China, each ton of Al₂O₃1-1.6 tons of red mud can be formed during the production, but the utilization rate is less than 15%, so that the comprehensive utilization of the red mud is widely concerned. The red mud mainly comprises iron oxide and hydroxide, aluminum oxide and hydroxide, kaolinite, quartz, calcite, titanium oxide and other substances, and is rich in metal elements. If the metal elements in the red mud can be effectively utilized, the waste is changed into valuable, and the method is one of effective sections for solving the problem of mass accumulation of the red mud in the current national conditions. In addition, the municipal sewage treatment plant can generate a lot of sludge which is rich inThe carbonized organic matter can form sludge carbon with rich pore structures and has good adsorption capacity.

Based on the prior art, the inventor develops a method for preparing the flue gas demercuration catalyst by using natural mineral soil montmorillonite, solid waste red mud and sludge as raw materials through long-term research, the obtained catalyst effectively utilizes metal Fe, Al, Ti and alkali contained in the red mud and organic matters in the sludge, has low cost, can solve the problems of accumulation of industrial waste and environmental pollution, and can change waste into valuable when being applied to flue gas demercuration so as to treat waste with waste. The preparation method has the advantages of simple process, mild conditions and wide application prospect.

Disclosure of Invention

The invention aims to provide a method for preparing a demercuration catalyst by using natural ore soil and waste residues, which effectively utilizes metals such as Fe, Al, Ti and the like and alkali contained in red mud to simultaneously carry out pillared modification and loading on montmorillonite, and then the mixture is mixed and carbonized with sludge to form a porous structure. The catalyst prepared by the invention has the advantages of high porosity, large specific surface area and stable metal immobilization, and the specific surface area can reach 178m²Per g, pore volume up to 0.49m³The mercury removal catalyst is applied to flue gas mercury removal, and can realize Hg at a lower temperature⁰High efficiency oxidation.

Specifically, the method for preparing the demercuration catalyst by using the natural ore soil and the waste residue comprises the following steps:

(1) adding red mud into water with the volume 2-5 times that of the red mud, continuously stirring, filtering, collecting filtrate, and recovering alkali in the red mud, wherein the filtrate is recorded as s 1; adding 0.1-0.8mol/L hydrochloric acid into the obtained red mud, adding acid, and stirring for 0.5-2h to dissolve partial metal Al and Fe in the red mud, wherein the liquid-solid ratio L/S =2-10mL/g, and the obtained suspension is marked as S2;

(2) slowly adding the filtrate S1 into the suspension S2 under continuous stirring, adding the amount of liquid-solid ratio L/S =2-5mL/g, continuously adding water with the volume of 15-20 times that of the filtrate S1, stirring for 1-3h, standing and aging to ensure that dissolved Al and Fe form hydroxyl compounds, and recording the obtained suspension as S3;

(3) adding dried montmorillonite into the suspension s3, wherein the adding amount is 0.5-2 times of the mass of the solid in the suspension, continuously stirring to ensure that hydroxy iron aluminum carries out pillared modification on the montmorillonite, standing for aging, filtering, washing and drying to obtain a mixture of red mud and pillared montmorillonite;

(4) and mixing the mixture of the red mud and the pillared montmorillonite with 10-20wt% of dehydrated dry sludge, roasting and carbonizing at 900 ℃ for 5-10h under a nitrogen atmosphere, and continuously roasting at 500 ℃ for 2-6h under an air atmosphere at 300-.

The obtained demercuration catalyst takes sludge carbon, pillared montmorillonite, aluminosilicate and the like as carriers, and takes loaded ferric oxide, alumina, titanium oxide and other small amount of metal oxides as active components. Wherein, transition metal oxide iron oxide is used as a main catalytic active component, titanium oxide and other small amount of metal components are used as auxiliary agents, and aluminum oxide can regulate the acidity of the catalyst. Organic matters in the sludge are continuously volatilized in the carbonization process, and the volatilized gas can effectively expand the pores of the catalyst, so that the catalyst forms a loose and porous structure, and the mass transfer is enhanced.

Furthermore, the red mud is Bayer process red mud, and is marked by mass fraction Al₂O₃5-20wt% of Fe₂O₃The content is 5-35 wt%.

Further, the montmorillonite is acid-pretreated montmorillonite.

Further, the aging in the steps (2) and (3) is carried out at room temperature, and the aging time is 6-10 h.

Compared with the prior art, the invention has the beneficial effects that:

(1) the flue gas demercuration catalyst provided by the invention adopts natural minerals and industrial wastes as raw materials, is low in cost, can solve the problems of accumulation of the industrial wastes and environmental pollution, changes waste into valuable, and treats waste with waste.

(2) The preparation method has simple process and mild conditions, and is suitable for large-scale production.

(3) According to the inventionThe specific surface area of the flue gas demercuration catalyst can reach 178m²Per g, Hg can be achieved at lower temperatures (200 ℃ C. and 300 ℃ C.)⁰High efficiency catalytic oxidation of Hg⁰The oxidation rate can reach 70-80%, is superior to the existing Mn/montmorillonite catalyst (65-70%), and has wide application prospect.

Drawings

FIG. 1 shows N of Cat1, Cat2 and Cat3₂-adsorption/desorption isotherms; wherein, A is Cat1, B is Cat2, and C is Cat 3.

FIG. 2 shows Hg at different temperatures for Cat1, Cat2, Cat3⁰Oxidation rate of (c).

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.