阅读说明：本技术 脱汞脱硝高效催化剂及其制备方法与应用 (Mercury-removing and denitration efficient catalyst and preparation method and application thereof ) 是由 王书肖 李国良 吴清茹 游小清 邵森 于 2019-04-18 设计创作，主要内容包括：本发明涉及一种新型催化剂,具体涉及一种脱汞脱硝高效催化剂及其制备方法与应用。本发明脱汞脱硝高效催化剂是以TiO<Sub>2</Sub>为载体,通过浸渍、微波及焙烧将CuO、CeO<Sub>2</Sub>和WO<Sub>3</Sub>均匀分散于该载体中而制得。在N<Sub>2</Sub>+6％O<Sub>2</Sub>烟气组分下,本发明催化剂的零价汞氧化效率高达96.2以上,在脱硝和SO<Sub>2</Sub>存在条件下(6％O<Sub>2</Sub>、100ppm NO、100ppm NH<Sub>3</Sub>和100ppm SO<Sub>2</Sub>)依然可以达到82.5％以上,表现出良好的氧化性能和抗硫性。本发明采用浸渍方法制备汞氧化催化剂,方法操作简便,试剂低毒环保,成本低廉,适合规模化生产等特点。(The invention relates to a novel catalyst, and in particular relates to a mercury removal and denitration efficient catalyst, and a preparation method and application thereof. The mercury-removing denitration high-efficiency catalyst is TiO 2 As a carrier, CuO and CeO are impregnated, microwaved and roasted 2 And WO 3 Uniformly dispersing in the carrier. In N 2 +6％O 2 Under the components of flue gas, the zero-valent mercury oxidation efficiency of the catalyst is as high as more than 96.2, and the catalyst can be used for denitration and SO 2 In the presence of (6% O) 2 、100ppm NO、100ppm NH 3 And 100ppm SO 2 ) Still can reach more than 82.5 percent, and shows good oxidation performance and sulfur resistance. The invention adopts an impregnation method to prepare mercury oxidation catalystThe reagent and the method have the characteristics of simple and convenient operation, low toxicity, environmental protection, low cost, suitability for large-scale production and the like.)

1. The mercury-removing denitration high-efficiency catalyst is characterized by comprising TiO₂As carrier, CuO, CeO₂And WO₃Is uniformly dispersed in the carrier.

2. The efficient catalyst for mercury removal and denitration according to claim 1, wherein the molar ratio of the copper element, the cerium element and the tungsten element loaded in the catalyst is (1-10):9 (1-10), and preferably 5:5: 9.

3. The mercury-removal and denitration efficient catalyst according to claim 1 or 2, wherein the loading amount of copper element in the catalyst is 1-10%, preferably 5%; and/or the presence of a gas in the gas,

the loading amount of the cerium element in the catalyst is 1-10%, and preferably 5%; and/or the presence of a gas in the gas,

the loading amount of the tungsten element in the catalyst is 5-10%, and the tungsten element is preferably 9%.

4. The efficient catalyst for mercury removal and denitration of claim 1, wherein the loading amounts of copper, cerium and tungsten in the catalyst are respectively 5%, 5% and 9%; or 1%, 5% and 9% respectively; or 10%, 5%, 9% respectively.

5. The mercury-removing and denitration efficient catalyst according to any one of claims 1 to 3, wherein the sum of the loading amounts of the copper element, the cerium element and the tungsten element in the catalyst is 15-24%, preferably 19%.

6. A process for preparing a catalyst as claimed in any one of claims 1 to 5, characterized in that TiO is used₂As carrier, CuO and CeO are impregnated, treated by microwave and roasted₂And WO₃Uniformly dispersed in the carrier.

7. A process for preparing a catalyst as claimed in any one of claims 1 to 5, which comprises:

1) adding Ce (NO)₃)₃·6H₂Adding O into deionized water, and adding a proper amount of oxalic acid; then 5 (NH) is added₄)₂O·12WO₃·5H₂O and Cu (NO)₃)₂Preparing a dipping solution; then adding TiO₂Preparing a mixed solution; microwave treatment;

2) and stirring, drying, roasting and cooling the mixed solution after microwave treatment.

8. The process for preparing the catalyst according to claim 7, wherein the microwave treatment time is 5 to 30min, preferably 15 min; the microwave power is 600-800 w.

9. The preparation method according to claim 7 or 8, characterized in that the roasting temperature is 450-550 ℃, and the roasting time is 3-5 h; preferably, the roasting temperature is 500 ℃ and the roasting time is 4 hours.

10. Use of the catalyst of any one of claims 1 to 5 or the catalyst prepared by the process of any one of claims 6 to 9 in the catalytic oxidation of Hg⁰The use of (1); preferably applied to Hg in coal-fired flue gas⁰Catalytic oxidation of (2).

Technical Field

The invention relates to a novel catalyst, in particular to a mercury removal and denitration efficient catalyst with good sulfur resistance and a preparation method thereof.

Background

Mercury, commonly known as mercury, and having the chemical symbol of Hg, is a heavy metal that can exist in gaseous and liquid forms at room temperature. Mercury and its compounds are widely present in natural environments, such as rocks, sediments, minerals, etc., and mainly present in the form of cinnabar (HgS). The mercury has long-distance migration and biological enrichment, can be converted into highly toxic methyl mercury in the nature, and has great harm to the environment and human health. Mercury exists in three main forms in atmospheric environments: gaseous elemental mercury (Hg)⁰) Gaseous active mercury (Hg)²⁺) And particulate mercury (Hg)_p). Mercury is mainly Hg in atmospheric environment⁰The mercury can stay in the atmosphere for a period of months to a year, and is transmitted along with the air flow for a long distance, so that the mercury pollutes the environment of a region far away from a pollution source, and serious health and economic losses are caused. In order to effectively suppress the use, release and emission of mercury on a global scale and reduce the damage of mercury to the environment and human health, the international society has agreed in 2013 on a mercury document with legal constraints and generates a water guarantee on mercury, which takes effect in 2017 on 8-16 th, wherein the coal-fired industry is the key control source of the convention. Therefore, the research on the flue gas demercuration in the coal burning industry is of great significance.

Taking a coal-fired power plant as an example, the pollution control measures basically already include Selective Catalytic Reduction (SCR) or Selective Non-catalytic Reduction (SNCR) denitration measures, cloth bag dust removal (FF) or electric dust removal (ESP) dust removal equipment, Wet Desulfurization (WFGD) equipment, and Wet Electrostatic precipitation (WESP). With country to NOx and SO₂The control is tightened, and denitration equipment and wet desulphurization equipment are gradually added in the coal-fired industrial boiler and the cement industry. Under the condition of pollution control, the country plans to adoptThe method of cooperative control of various pollution control facilities is used for reducing the emission of mercury in flue gas (Wu Q, et al, environ Sci Tehnol, 2018,52(19): 11087-. In flue gas, over 99 percent of Hg_pCan be removed by dust removing equipment, and more than 80 percent of Hg²⁺Can be removed by a wet desulphurization device, but Hg⁰Are difficult to capture directly by pollution control equipment (ZHao S, ethyl. RSC adv.,2015,5(39):30841 30850; ZHao L, Fuel,2015,153(1): 361-. In coal combustion flue gas, Hg⁰About total mercury (Hg) is contained^T) About 20 percent of the mercury in smoke of low-grade coal such as brown coal and the like⁰The content may account for more than 80% of the total mercury emission (Guo X, et al&Fuels,2007,21(2): 898-902). Therefore, Hg⁰The removal of the mercury is an important content for solving the problem of mercury pollution emission of coal-fired flue gas. Hg is introduced via a catalyst⁰Conversion to Hg²⁺And then capturing Hg by a desulfurization device²⁺Thereby effectively reducing Hg by means of the cooperative control of the existing equipment⁰Emissions are an ideal technical approach to control mercury emissions. The key step of the technology is to prepare high-efficiency Hg⁰An oxidation catalyst.

Review of domestic and foreign literature found that, at present, Hg⁰Oxidation catalysts can be classified into three broad categories: vanadium-tungsten-titanium denitration catalyst, noble metal oxide catalyst and transition metal oxide catalyst (Dranga B-A, et al. catalysts,2012,2(4):139-&Technology,2011,45(13): 5725-. Vanadium tungsten titanium denitration catalyst is widely used in Nitrogen Oxide (NO)_x) Reduction removal of Hg⁰Also has certain oxidation performance (Chen C, Jia, oral&Fuels,2018,32(6):7025 and 7034; usberti N, et al applied Catalysis B, Environmental,2016,193(3), 121-; zhang X, et al applied Surface Science,2015,347(8): 392-; noble metal oxide catalyst for Hg⁰The oxidation efficiency is good, but the expensive price of the noble metal limits the wide application of the noble metal catalyst; transition metal oxide type catalyst for Hg under certain conditions⁰Has the advantages ofGood catalytic oxidation (Li H, et al. applied Catalysis B: Environmental,2012, 111-. Wherein Ce oxide is in pairs of Hg⁰Has good catalytic oxidation capability, low cost, low toxicity and good application prospect. However, researches show that the reaction temperature window of the Ce-based oxide is narrow, the sulfur resistance is poor, and SO is generated₂The occurrence of (2) has a great influence on the mercury oxidation performance of the Ce-based oxide. Therefore, the proper doping reagent is adopted to improve the mercury oxidation efficiency and sulfur resistance of the catalyst, improve the active oxygen content on the surface of the catalyst, and improve the acidity and alkalinity on the surface of the catalyst, SO that the sulfur resistance of the catalyst is improved, and a novel combined demercuration and denitration catalyst is developed to overcome SO₂The problem of Ce-based catalyst inhibition.

Disclosure of Invention

The invention provides a high-efficiency catalyst for mercury removal and denitration, which has good denitration performance, sulfur resistance and mercury oxidation capability. The catalyst is prepared by adopting a cheap and low-toxicity active reagent, and has the advantages of simple method and easy engineering application.

The mercury-removing denitration high-efficiency catalyst provided by the invention is prepared from TiO₂As carrier, CuO, CeO₂And WO₃Is uniformly dispersed in the carrier.

Further, the molar ratio of the copper element, the cerium element and the tungsten element loaded in the catalyst is (1-10): (1-10):9, and preferably 5:5: 9.

Further, the loading of the copper element in the catalyst is 1-10%, for example, 1%, 5% or 10%, preferably 5%.

Furthermore, the loading amount of the cerium element in the catalyst is 1 to 10%, for example, 1%, 5% or 10%, preferably 5%.

Further, the loading amount of the tungsten element of the catalyst is 5-10%, and the loading amount is preferably 9%.

If not specifically indicated, the loading amount of the catalyst refers to a certain element or an oxide of the element loaded in the catalyst and the carrier TiO₂Article ofMass ratio of the components.

Furthermore, the sum of the loading amounts of the copper element, the cerium element and the tungsten element in the catalyst is 15-24%, and is preferably 19%.

Further, the TiO₂Is commercial TiO₂(P25)。

The catalyst of the invention may be TiO₂As carrier, CuO and CeO are impregnated, treated by microwave and roasted₂And WO₃Uniformly dispersed in the carrier.

Specifically, the preparation method of the catalyst comprises the following steps:

1) adding Ce (NO)₃)₃·6H₂Adding O into deionized water, and adding a proper amount of oxalic acid; then 5 (NH) is added₄)₂O·12WO₃·5H₂O and Cu (NO)₃)₂Preparing a dipping solution; then adding TiO₂Preparing a mixed solution; microwave treatment;

2) and stirring, drying, roasting and cooling the mixed solution after microwave treatment.

Further, the amount of oxalic acid added is such that 5 (NH) is added₄)₂O·12WO₃·5H₂No precipitation after O. Typically, a 5 wt% oxalic acid solution may be used.

Further, in the impregnation solution, Ce (NO)₃)₃·6H₂O、5(NH₄)₂O·12WO₃·5H₂O and Cu (NO)₃)₂The concentration of (B) is preferably 1-2 mol.L^-1。

Further, copper element, cerium element, tungsten element and TiO in the mixed solution₂The molar ratios of (A) to (B) are 1-10%, 5% and 9%, respectively.

Further, the microwave treatment time is 5-30min, preferably 15 min; the microwave power is 600-800 w.

Researches show that the mixed reagent can be uniformly loaded on TiO by microwave treatment₂On a carrier.

Further, the stirring time in the step 2) is 12-48h, preferably 24h, and the condition of stirring to uniformly mix the suspension is preferred.

Further, step 2) may be dried at 110 ℃ (oven) for 12 h.

Further, the roasting temperature is 450-550 ℃, and the roasting time is 3-5 h; preferably, the roasting temperature is 500 ℃ and the roasting time is 4 hours. For example, it may be fired in a muffle furnace.

The invention also comprises the application of the catalyst in catalytic oxidation of Hg⁰Especially for Hg in coal-fired flue gas⁰Catalytic oxidation of (2).

The catalyst prepared by the invention gets rid of the dependence of the traditional catalyst on HCl for oxidizing zero-valent mercury, and shows good mercury oxidation efficiency under the HCl-free condition, 81.2-97.5% (100-450 ℃); the 5% CuO enables Cu to be doped in a Ce-O-W crystal structure to form a double oxidation-reduction structure (Ce-O-Cu), SO that the chemical structure of the catalyst is more variable, more mercury oxidation sites are provided, and CuO is easier to react with SO₂React to form copper sulfate, thereby protecting CeO₂Active sites improve the sulfur resistance of the catalyst. In addition, the mercury oxidation catalyst is prepared by adopting an impregnation method, and the method has the characteristics of simplicity and convenience in operation, low toxicity and environmental protection of the reagent, low cost, suitability for large-scale production and the like.

Drawings

Fig. 1 shows the effect of the amount of CuO impregnation on the mercury oxidation efficiency of the catalyst.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. The examples do not show the specific techniques or conditions, according to the technical or conditions described in the literature in the field, or according to the product specifications. The reagents or instruments used are conventional products available from regular distributors, not indicated by the manufacturer.

TiO used hereinafter₂Is commercial TiO₂(P25)。