阅读说明：本技术 高效抗水热和抗硫性能的脱汞催化剂及其制备方法与应用 (High-efficiency anti-hydrothermal and anti-sulfur demercuration 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,具体涉及一种高效抗水热和抗硫性能的脱汞催化剂及其制备方法与应用。本发明所述脱汞催化剂是以CH<Sub>4</Sub>作为燃料与空气混合形成预混合气体,采用火焰合成的方式将有机试剂雾化燃烧制备而成的。该催化剂在N<Sub>2</Sub>+6％O<Sub>2</Sub>烟气组分下,催化剂氧化效率保持在90％以上；尤其在200-400℃温度区间,催化剂氧化效率接近100％。100ppmSO<Sub>2</Sub>添加对催化剂脱效率的抑制影响低于8％,水蒸气对催化剂汞氧化效率抑制作用低于5％,SO<Sub>2</Sub>和H<Sub>2</Sub>O对催化剂的汞氧化效率抑制作用低于13％；催化剂脱硝效率保持在75.3％-92.6％,说明催化剂具有较好的抗硫抗水性。(The invention relates to a novel catalyst, in particular to a demercuration catalyst with high-efficiency hydrothermal resistance and sulfur resistance, and a preparation method and application thereof. The demercuration catalyst of the invention is CH 4 The fuel is mixed with air to form premixed gas, and the premixed gas is prepared by atomizing and burning an organic reagent in a flame synthesis mode. The catalyst is in N 2 +6％O 2 Under the components of the flue gas, the oxidation efficiency of the catalyst is kept above 90%; especially in the temperature range of 200 ℃ and 400 ℃, the oxidation efficiency of the catalyst is close to 100 percent. 100ppm SO 2 Addition of para-catalystThe inhibition effect of the removal efficiency is less than 8 percent, the inhibition effect of the water vapor on the mercury oxidation efficiency of the catalyst is less than 5 percent, and the SO 2 And H 2 The inhibition effect of O on the mercury oxidation efficiency of the catalyst is lower than 13%; the denitration efficiency of the catalyst is kept between 75.3 and 92.6 percent, which shows that the catalyst has better sulfur resistance and water resistance.)

1. A preparation method of a high-efficiency demercuration catalyst is characterized by comprising the following steps: introducing high-pressure air into the catalyst precursor to form aerosol with the particle size of 200-500nm, and then heating, burning, evaporating, separating out solute and agglomerating to form the catalyst;

the precursor comprises diisopropyl di (acetylacetonate) titanate, and also comprises any one, any two or any three of a cerium source, a tungsten source and a copper source; wherein the cerium source is cerium isooctanoate or cerium 2-ethylhexanoate, the tungsten source is tungsten hexacarbonyl, and the copper source is copper 2-ethylhexanoate.

2. The process according to claim 1, wherein the fuel gas used is CH₄Premixed gas formed by mixing with air, in which CH₄The volume ratio to air is preferably (7-9): 90-100, more preferably 8: 100.

3. The production method according to claim 1 or 2, wherein the flow rate of the premixed gas is 15 to 25L-min^-1Preferably 20 L.min^-1。

4. A method according to any one of claims 1 to 3, wherein the flame temperature used is stabilized at around 1600 ℃.

5. The method according to any one of claims 1 to 4, wherein the catalyst precursor is prepared in the form of a solution and then an aerosol is formed by high-pressure air, and the solvent is preferably tetrahydrofuran.

6. The production method according to any one of claims 1 to 5, comprising:

preparing a catalyst precursor into a solution by using tetrahydrofuran, introducing high-pressure air into the solution to form aerosol with the particle size of 200-500nm in an atomizer, and then performing flame heating, combustion, evaporation, solute precipitation and agglomeration to form a high-efficiency catalyst; the atomization air flow of the precursor is kept at 2 L.min < -1 >;

the gas is CH₄The premixed gas is mixed with air according to the volume ratio of 8:100, and the flow rate of the premixed gas is 20 L.min^-1The flame temperature used was stabilized around 1600 ℃.

7. A high efficiency demercuration catalyst prepared by the method of any one of claims 1 to 6.

8. The catalyst of claim 7, optionally being one of:

1)CeO₂/TiO₂wherein the molar content of Ce element is 1-15%;

2)CeO₂-WO₃/TiO₂wherein the molar content of Ce element is 1-10%; the molar content of the W element is 5-10%;

3)CuO-CeO₂-WO₃/TiO₂wherein the molar content of the Cu element is 1-15%; the molar content of Ce element is 1-15%; the molar content of the W element is 5-10%.

9. The catalyst of claim 7, optionally being one of:

1)CeO₂/TiO₂wherein the molar content of Ce element is 5%;

2)CeO₂-WO₃/TiO₂wherein the molar content of Ce element is 5% or 10%; the molar content of the W element is 9 percent;

3)CuO-CeO₂-WO₃/TiO₂wherein the molar content of the Cu element is 5% or 10%; the molar content of Ce element is 5% or 10%; the molar content of the W element was 9%.

10. Use of the catalyst of any one of claims 7-9 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 demercuration catalyst with good water heat resistance and sulfur resistance, and a preparation method and application thereof.

Background

Mercury, commonly known as mercury, is a heavy metal that can exist in gaseous and liquid forms at ambient temperatures. The mercury can be long-distance migratory and biological enrichment, and can be converted into highly toxic methyl mercury in nature, thus having great harm to the environment and human health. 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. Mercury mainly exists in three forms in coal-fired flue gas: gaseous elemental mercury (Hg)⁰) Gaseous active mercury (Hg)²⁺) And particulate mercury (Hg)_p). Wherein Hg²⁺And Hg_pCan be respectively removed by wet desulphurization and dust removal equipment in the coal industry, but Hg⁰Are not readily soluble in water and are difficult to remove by pollution control measures. 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. Therefore, the key of the mercury removal of flue gas in the coal-fired industry is to remove Hg⁰Conversion of Hg²⁺And is removed by the wet desulphurization equipment on the back surface. So that high-efficiency Hg is prepared⁰The catalyst is a main problem for effectively controlling the mercury emission of the flue gas.

The research on domestic and foreign documents shows that the water is hotPoor performance and low sulfur resistance of Hg⁰The main problems facing oxidation catalysts. Because the traditional catalyst is prepared by roasting, the roasting temperature is usually not higher than 500 ℃, and the catalyst activity is reduced due to the obvious collapse of the catalyst structure when the temperature of the catalyst is higher than 500 ℃. Due to the different fuel components and the fluctuation of heat energy demand, the flue gas temperature may have large variation, so that the catalyst is required to have a wider reaction temperature window and better hydrothermal resistance. The study on the reaction temperature window has been relatively comprehensive, but the study on the hydrothermal resistance of the catalyst has been relatively small. SO (SO)₂Mercury oxidation catalysts generally exhibit poor sulfur resistance because they have similar adsorptive oxidation sites as mercury. 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 of the surface of the catalyst, thereby improving the sulfur resistance of the catalyst. Therefore, the preparation of the catalyst with good hydrothermal resistance and sulfur resistance has important significance for mercury oxidation removal.

Disclosure of Invention

The invention provides a high-efficiency anti-hydrothermal and anti-sulfur demercuration catalyst, which is synthesized by adopting a flame method in SO₂The catalyst shows excellent zero-valent mercury oxidation capability under the existing condition and also has good denitration efficiency performance.

Specifically, the demercuration catalyst of the invention is CH₄The fuel is mixed with air to form premixed gas, and the premixed gas is prepared by atomizing and burning an organic reagent in a flame synthesis mode.

The invention firstly provides a preparation method of a high-efficiency demercuration catalyst, which comprises the following steps: introducing high-pressure air into the catalyst precursor to form aerosol with the particle size of 200-500nm, and then introducing the aerosol into flame for heating, burning, evaporating, separating out solute and agglomerating to form the catalyst.

Further, the fuel gas used is CH₄Premixed gas formed by mixing with air, in which CH₄The volume ratio to air is preferably (7-9): 90-100, more preferably 8: 100.

The premixed gasThe body is slightly higher than CH₄Can ensure CH₄The combustion is sufficient to prevent the formation of soot in the combustion flame that blocks the catalyst pore structure.

Further, the flow rate of the premixed gas is 15-25 L.min^-1Preferably 20 L.min^-1。

Further, the flame temperature used was stabilized around 1600 ℃.

Further, the precursor comprises diisopropyl di (acetylacetonate) titanate, and any one, any two or any three of a cerium source, a tungsten source and a copper source; wherein the cerium source is cerium isooctanoate or cerium 2-ethylhexanoate, the tungsten source is tungsten hexacarbonyl, and the copper source is copper 2-ethylhexanoate.

In order to form an aerosol, the catalyst precursor may be prepared in the form of a solution in advance and then an aerosol may be formed by high-pressure air, and the solvent used is preferably tetrahydrofuran.

The catalyst precursor may be passed through high pressure air to form an aerosol in the atomizer.

The component ratios of the precursors may be adjusted according to the elemental ratios in the target catalyst.

Specifically, the preparation method of the mercury removal catalyst with high-efficiency hydrothermal resistance and sulfur resistance comprises the following steps:

preparing a catalyst precursor into a solution by using tetrahydrofuran, introducing high-pressure air into the solution to form aerosol with the particle size of 200-500nm in an atomizer, and then performing flame heating, combustion, evaporation, solute precipitation and agglomeration to form a high-efficiency catalyst; the atomization air flow of the precursor is kept at 2 L.min < -1 >;

the gas is CH₄The premixed gas is mixed with air according to the volume ratio of 8:100, and the flow rate of the premixed gas is 20 L.min^-1The flame temperature used was stabilized around 1600 ℃.

Specifically, the catalyst synthesized in flame was adsorbed on an immobilization plate (1mm aluminum plate) under the action of thermophoresis. The water cooling device is arranged below the stagnation plate, so that the temperature of the stagnation plate is ensured to be below 50 ℃, and the collected catalyst is rapidly cooled down. After the reaction is finished, the catalyst on the stagnation plate is collected and can be used for mercury oxidation experiments.

The invention also discloses the mercury removal catalyst with high-efficiency hydrothermal resistance and sulfur resistance, which is prepared by the method.

In some preferred embodiments of the present invention, the prepared demercuration catalyst is as follows:

1)CeO₂/TiO₂wherein the molar content of the Ce element is 1-15%, and more preferably 5%;

2)CeO₂-WO₃/TiO₂wherein the molar content of Ce element is 1-10%, more preferably 5% or 10%; the molar content of the W element is 5-10%, more preferably 9%;

3)CuO-CeO₂-WO₃/TiO₂wherein the molar content of the Cu element is 1-15%, and more preferably 5% or 10%; the molar content of the element Ce is 1-15%, more preferably 5% or 10%; the molar content of the W element is 5 to 10%, more preferably 9%.

In some embodiments of the present invention, the precursors of the catalyst are mixed and adjusted according to the target catalyst element ratio, and the precursor ratios and the formed catalyst numbers are listed in table 1.

TABLE 1 content of various catalyst elements

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

In N₂+6％O₂The invention is CuO (10) -CeO under the smoke component₂(10)-WO₃(9)/TiO₂The oxidation efficiency of the catalyst is kept above 90%, and particularly in the temperature range of 200 ℃ and 400 ℃, the oxidation efficiency of the catalyst is close to 100%. 100ppm SO₂The inhibition effect of the addition on the catalyst removal efficiency is less than 8 percent, the inhibition effect of the water vapor on the catalyst mercury oxidation efficiency is less than 5 percent, and the SO₂And H₂The inhibition effect of O on the mercury oxidation efficiency of the catalyst is lower than 13%; CuO (10) -CeO₂(10)-WO₃(9)/TiO₂The denitration efficiency of the catalyst is kept between 75.3 and 92.6 percent, which shows that the catalyst has better sulfur resistance and water resistance. The invention provides a simple, convenient and efficient preparation technology for preparing the hydrothermal-resistant and sulfur-resistant catalyst.

Drawings

FIG. 1 is a schematic diagram of a catalyst flame synthesis system.

FIG. 2 shows the results of mercury oxidation efficiency tests for various catalysts for flame synthesis.

FIG. 3 shows flame synthesis of CuO (10) -CeO₂(10)-WO₃(9)/TiO₂The research result of sulfur resistance and water resistance of the catalyst.

FIG. 4 shows the effect of hydrothermal treatment on the mercury oxidation performance of a flame synthesis and impregnation catalyst.

FIG. 5 shows CuO (10) -CeO₂(10)-WO₃(9)/TiO₂-F and CuO (5) -CeO₂(5)-WO₃(9)/TiO₂I catalyst before and after hydrothermal treatment Pyridine-IR test results.

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.

The catalyst flame synthesis system used in the following examples is shown in FIG. 1.