CN105749937A - Copper chloride-modified SCR catalyst, preparation method and application thereof - Google Patents

Abstract

The invention provides a copper chloride-modified SCR catalyst and its preparation method and application. The SCR catalyst is a catalyst formed by supporting copper chloride-modified metal oxides on iron-based pillared attapulgite. The preparation method comprises the following steps: preparing pure attapulgite; preparing iron-based pillared attapulgite; dissolving manganese nitrate or cerium nitrate in citric acid to form a mixed precursor solution, or dissolving ammonium metavanadate in oxalic acid solution for heating and aging Form a mixed precursor solution; weigh iron pillared attapulgite and add it to the mixed precursor solution to fully stir and age; dry, roast, and grind to obtain MnO ₂ /Fe?ATP or CeO ₂ /Fe?ATP or V ₂ O ₅ /Fe ?ATP catalyst: Weigh CuCl ₂ , add acetone and stir until completely dissolved, add the obtained catalyst under continuous stirring, stir, suction filter, dry, and calcinate to obtain a composite catalyst. The invention has the beneficial effects of low cost and high denitrification and mercury removal efficiency.

Description

A copper chloride modified SCR catalyst and its preparation method and application

technical field

The invention belongs to the technical field of chemical industry, and in particular relates to a cupric chloride-modified SCR catalyst and a preparation method and application thereof.

Background technique

In recent years, people have noticed that some substances produced during coal combustion have a greater impact on the environment, and these substances include mercury and nitrogen oxides. Coal-fired boilers, as the main anthropogenic source of mercury pollution in the environment, have attracted widespread attention worldwide. Sulfur dioxide and nitrogen oxides produced by coal burning are one of the main causes of "acid rain" and "acid smog", and the highly toxic mercury is also one of the toxic factors in haze weather. Because mercury has a particularly high accumulation in the environment and in organisms, it is quite toxic to humans and wildlife even at very low concentrations. The U.S. Environmental Protection Agency defines mercury as a highly hazardous Elements.

Selective Catalytic Reduction (SCR) is a denitrification technology widely used in industry at present, and this method can achieve a reduction rate of _NOx of 80% to 90%. Many scholars at home and abroad have carried out relevant research on various catalysts and achieved certain results. However, its active temperature window is 300-400°C. High temperature will cause the catalyst to sinter, and side reactions such as the oxidation of NH3 to NO will occur, increasing the consumption of NH3. When the temperature is lower than 200°C, it will not have good catalytic activity.

In recent years, scientists have done a lot of exploration in the research and development of low-temperature SCR catalysts, including two types of catalysts, noble metals and transition metal oxides. Noble metal catalysts have good catalytic activity at low temperature, but their disadvantages such as high cost, narrow operating temperature window, and sensitivity to SO2 limit their large _- scale industrial application.

At present, SCR catalysts are mainly used in flue gas denitrification in industry. Recently, many researchers have studied SCR catalysts for mercury removal. Metal oxides need to be loaded on a carrier to be able to remove mercury. The commonly used carriers are titanium dioxide, silicon dioxide, and activated carbon. However, this type of catalyst is easily poisoned, difficult to regenerate, and the cost is too high to realize industrialization.

Our country is rich in attapulgite resources, but its resource utilization level is relatively low. Attapulgite (ATP), also known as palygorskite, is a layered chain magnesium-rich silicate clay mineral, which is needle-like or fibrous, with a large specific surface area (146-210m ² /g). Reactive -OH organization, special layer chain structure can produce developed zeolite-like pores, and has the characteristics of general clay: cation exchange, water absorption, expandability, etc.

Contents of the invention

The purpose of the present invention is to provide a copper chloride modified SCR catalyst with low production cost and high denitrification and mercury removal efficiency and a preparation method thereof.

Technical scheme of the present invention is:

A cupric chloride-modified SCR catalyst, in particular a catalyst in which cupric chloride-modified metal oxides are supported on iron-based pillared attapulgite.

Preferably, the metal oxide is MnO ₂ , CeO ₂ or V ₂ O ₅ .

Another aspect of the present invention also includes the application of the SCR catalyst modified by copper chloride in demercuration and denitrification of flue gas.

Another aspect of the present invention, also includes a kind of preparation method of the cupric chloride modified SCR catalyst, comprises the following steps:

(1) prepare pure attapulgite;

( ₂ ) Prepare NaOH solution and FeCl3 solution, under the condition of continuous stirring, _NaOH solution is slowly added to FeCl3 solution, the resulting mixed solution is aged under stirring at room temperature;

(3) Put pure attapulgite into distilled water and fully stir to prepare the attapulgite suspension, take the mixed solution obtained in step (2) and add it dropwise to the attapulgite suspension, continue stirring and aging;

(4) washing with deionized water after suction filtration until no ^Cl- exists, drying, calcining, and grinding to obtain iron-based pillared attapulgite;

(5) dissolving manganese nitrate or cerium nitrate in citric acid to form a mixed precursor solution, or dissolving ammonium metavanadate in oxalic acid solution for heating and aging to form a mixed precursor solution;

(6) Weighing iron pillar attapulgite and adding to step (5) to obtain mixed precursor body fluid and fully stirring and aging;

(7) drying, roasting and grinding to obtain MnO ₂ /Fe-ATP or CeO ₂ /Fe-ATP or V ₂ O ₅ /Fe-ATP catalyst;

(8) Weigh CuCl ₂ , add acetone and stir until completely dissolved, slowly add the catalyst obtained in step (7) under constant stirring, stir at room temperature, suction filter, dry, and calcinate to obtain a composite catalyst.

Preferably, when step (5) dissolves manganese nitrate or cerium nitrate in citric acid to form a mixed precursor solution, add glacial acetic acid for aging in step (6), then adjust the pH with ammonia water, react to gel, and then Proceed to step (7).

Preferably, when the ammonium metavanadate is dissolved in the oxalic acid solution for heating and aging in step (5) to form a mixed precursor solution, phosphoric acid is added in step (6) as a binder.

Preferably, the specific preparation process of step (1) is to prepare and weigh attapulgite into distilled water and stir evenly, under the action of high shear force, add sodium hexametaphosphate aqueous solution, fully stir, and ultrasonically disperse the mixed solution , stand still, decant the supernatant suspension, centrifuge the obtained solid, wash with double distilled water until neutral, and dry to obtain pure attapulgite.

Preferably, the NaOH solution in the step ( ₂ ) is 0.4mol/L, the FeCl3 solution is 0.2mol/L, and the stirring aging time is 10h.

Preferably, the stirring temperature in the step (3) is 40° C., the stirring time is 24 hours, and the aging time is 12 hours.

Preferably, in the step (4), the drying temperature is 90° C., the calcination temperature is 300° C., and the time is 3 hours.

Preferably, in the step (7), the drying temperature is 80°C, the calcination temperature is 300-400°C, and the time is 3-6h.

Preferably, in the step (8), the drying temperature is 100° C., the drying time is 12 hours, and then put into a muffle furnace for calcination at 300° C. for 4 hours.

The advantages and positive effects that the present invention has are:

(1) Use cheap attapulgite instead of expensive activated carbon, titanium dioxide, etc. as the carrier of the catalyst, which reduces the production cost and is more suitable for industrial production.

(2) The catalyst has high denitrification and mercury removal efficiency in the low temperature region.

(3) The SCR denitrification equipment can be used when the catalyst denitrates and demercurizes, which reduces the equipment cost.

detailed description

The present invention will be described in detail below in conjunction with the embodiments.

Example 1:

The preparation of CuCl ₂ modified MnO ₂ /Fe-ATP comprises the following steps:

(1) Weigh 20g of attapulgite (ATP) into 200mL of distilled water and stir evenly. Under the action of a certain temperature and high shear force, add a certain concentration of sodium hexametaphosphate aqueous solution. After stirring for a period of time, the mixed solution Perform ultrasonic dispersion for a certain period of time, let stand, decant the supernatant suspension, centrifuge the obtained solid, wash it with double distilled water until it is neutral, and dry it at a certain temperature to obtain pure attapulgite.

(2) Prepare a certain amount of NaOH (0.4M) and FeCl ₃ (0.2M) solutions, and slowly add 100ml of 0.4mol/L NaOH solution to 100ml of 0.2mol/L FeCl ₃ solution under continuous stirring. The resulting mixed solution was stirred and aged at room temperature for 10 h.

(3) Weigh 2 g of pure attapulgite and put it into 50 ml of distilled water and stir thoroughly, take 50 ml of the solution obtained in (2) and add it dropwise to the attapulgite suspension. Stir continuously for 24 hours at 40°C and age for 12 hours.

(4) Wash with deionized water after suction filtration until no ^Cl- exists (detected with AgNO ₃ ). Dry at 90°C, calcined at 300°C for 3h, and grind to obtain iron-based pillared attapulgite.

(5) Dissolve 2 mmol of manganese nitrate in 50 ml of 2 mol/L citric acid solution to form a mixed precursor citric acid solution.

(6) Weigh 2g of iron pillared attapulgite and add (5) to the mixture and stir thoroughly. After stirring for 1 hour, 2 ml of glacial acetic acid was added and aged at 60° C. for 12 hours with stirring.

(7) Adjust the pH to 8 with ammonia water, and react until gelatinous at a temperature of 80°C. Dry at 80° C. for 24 hours, put it into a muffle furnace and bake at 400° C. for 6 hours in an air atmosphere, and then grind to obtain MnO ₂ /Fe-ATP.

(8) Weigh 0.25g of CuCl ₂ into a 100ml beaker, add 50ml of acetone and stir until completely dissolved, then slowly add 2g of the catalyst obtained in (7) under continuous stirring. Stir at room temperature for 2 hours, filter with suction, dry at 100° C. for 12 hours, and put into a muffle furnace for calcination at 300° C. for 4 hours to obtain a composite catalyst.

The flue gas mercury removal activity test of the obtained composite catalyst:

0.5 g of the prepared catalyst was placed in a fixed bed of a catalyst evaluation device, and the catalyst flue gas demercuration evaluation was carried out under the conditions of simulated flue gas. The simulated flue gas is composed of O ₂ , CO ₂ , SO ₂ , NO, HCl, N ₂ , the total flow of flue gas is 1L/min, the O ₂ content is 6%, the CO ₂ content is 12%, and the SO ₂ concentration is 400ppm , the concentration of NO is 800ppm, the concentration of Cl ₂ is 50ppm, the flow rate of NH ₃ is 1ml/min, and the rest is N ₂ . 100ml/min N ₂ (as the carrier of mercury vapor), simulated flue gas of zero-valent mercury 20±1μg/m ³ . When the temperature is 200°C and the space velocity is 38000h ^-1 , when the catalyst reaches the stable catalytic stage, the flue gas denitrification rate of the catalyst prepared above is 95.58%, and the oxidation rate of elemental mercury reaches 92.57%. Other conditions remain unchanged, when _1000ppm SO2 is added to the flue gas, the denitrification rate of the catalyst to the flue gas is reduced to 92.56%, and the oxidation efficiency of elemental mercury is reduced to 88.19%.

Example 2

The preparation of CuCl ₂ modified CeO ₂ /Fe-ATP comprises the following steps:

(1) Weigh 20g of attapulgite (ATP) into 200mL of distilled water and stir evenly. Under the action of a certain temperature and high shear force, add a certain concentration of sodium hexametaphosphate aqueous solution. After stirring for a period of time, the mixed solution Perform ultrasonic dispersion for a certain period of time, let stand, decant the supernatant suspension, centrifuge the obtained solid, wash it with double distilled water until it is neutral, and dry it at a certain temperature to obtain pure attapulgite.

(2) A certain amount of NaOH (0.4M) and FeCl ₃ (0.2M) solutions were prepared, and 100ml of 0.4mol/L NaOH solution was slowly added to 100ml of 0.2mol/L FeCl ₃ solution under continuous stirring. The resulting mixed solution was stirred and aged at room temperature for 10 h.

(3) Weigh 2 g of pure attapulgite and put it into 50 ml of distilled water and stir thoroughly, take 50 ml of the solution obtained in (2) and add it dropwise to the attapulgite suspension. Stir continuously for 24 hours at 40°C and age for 12 hours.

(4) Wash with deionized water after suction filtration until no Cl- exists (detected with AgNO ₃ ). Dry at 90°C, calcined at 300°C for 3h, and grind to obtain iron-based pillared attapulgite.

(5) Dissolve 2 mmol of cerium nitrate in 50 ml of 2 mol/L citric acid solution to form a mixed precursor citric acid solution.

(6) Weigh 2g of iron pillared attapulgite and add (5) to the mixture and stir thoroughly. After stirring for 1 hour, 2 ml of glacial acetic acid was added and aged at 60° C. for 12 hours with stirring.

(7) Adjust the pH to 8 with ammonia water, and react until gelatinous at a temperature of 80°C. Dry it at 80°C for 24 hours, put it into a muffle furnace and bake it at 400°C for 4 hours in an air atmosphere, and then grind it to obtain CeO ₂ /Fe-ATP.

(8) Weigh 0.25g of CuCl ₂ into a 100ml beaker, add 50ml of acetone and stir until completely dissolved, then slowly add 2g of the catalyst obtained in (7) under continuous stirring. Stir at room temperature for 2 hours, filter with suction, dry at 100° C. for 12 hours, and put into a muffle furnace for calcination at 300° C. for 4 hours to obtain a composite catalyst.

The flue gas mercury removal activity test of the obtained composite catalyst:

0.5 g of the prepared composite catalyst was placed in a fixed bed of a catalyst evaluation device, and the catalyst flue gas demercuration evaluation was carried out under the conditions of simulated flue gas. The simulated flue gas is composed of O ₂ , CO ₂ , SO ₂ , NO, HCl, N ₂ , the total flow of flue gas is 1L/min, the O ₂ content is 6%, the CO ₂ content is 12%, and the SO ₂ concentration is 400ppm , the concentration of NO is 800ppm, the concentration of Cl ₂ is 50ppm, the flow rate of NH ₃ is 1ml/min, and the rest is N ₂ . 100ml/min N ₂ (as the carrier of mercury vapor), simulated flue gas of zero-valent mercury 20±1μg/m ³ . When the temperature is 220°C and the space velocity is 38000h ^-1 , when the catalyst reaches the stable catalytic stage, the flue gas denitrification rate of the catalyst prepared above is 94.72%, and the oxidation rate of elemental mercury reaches 92.77%. Other conditions remain unchanged, when 1000ppm SO ₂ is added to the flue gas, the denitrification rate of the catalyst to the flue gas drops to 91.95%, and the oxidation efficiency of elemental mercury drops to 89.64%.

Example 3

The preparation of CuCl ₂ modified V ₂ O ₅ /Fe-ATP comprises the following steps:

(1) Weigh 20g of attapulgite (ATP) into 200mL of distilled water and stir evenly. Under the action of a certain temperature and high shear force, add a certain concentration of sodium hexametaphosphate aqueous solution. After stirring for a period of time, the mixed solution Perform ultrasonic dispersion for a certain period of time, let stand, decant the supernatant suspension, centrifuge the obtained solid, wash it with double distilled water until it is neutral, and dry it at a certain temperature to obtain pure attapulgite.

(2) Prepare a certain amount of NaOH (0.4M) and FeCl ₃ (0.2M) solutions, and slowly add 100ml of 0.4mol/L NaOH solution to 100ml of 0.2mol/L FeCl3 solution under continuous stirring. The resulting mixed solution was stirred and aged at room temperature for 10 h.

(3) Weigh 2 g of pure attapulgite and put it into 50 ml of distilled water and stir thoroughly, take 50 ml of the solution obtained in (2) and add it dropwise to the attapulgite suspension. Stir continuously for 24 hours at 40°C and age for 12 hours.

(4) Wash with deionized water after suction filtration until no ^Cl- exists (detected with AgNO ₃ ). Dry at 90°C, calcined at 300°C for 3h, and grind to obtain iron-based pillared attapulgite.

(5) Weigh 2.5g of oxalic acid and dissolve it in 50ml of deionized water, heat to completely dissolve the oxalic acid, add 2mmol NH ₄ VO ₃ and stir to dissolve.

(6) Heating the mixed solution (5) at a constant temperature of 60° C., the solution changes from light yellow to dark green and then dark blue. The prepared solution was aged for 12h.

(7) Add a certain amount of Fe-ATP and a small amount of phosphoric acid (as a binder) into the impregnation solution, heat and stir, and put it in a constant temperature water bath until the water is evaporated to dryness, dry at 80°C, and calcined at 300°C 3h. The product obtained by grinding is V ₂ O ₅ /Fe-ATP.

(8) Weigh 0.25g of CuCl ₂ into a 100ml beaker, add 50ml of acetone and stir until completely dissolved, then slowly add 2g of the catalyst obtained in (7) under continuous stirring. Stir at room temperature for 2 hours, filter with suction, dry at 100° C. for 12 hours, and put into a muffle furnace for calcination at 300° C. for 4 hours to obtain a composite catalyst.

The flue gas mercury removal activity test of the obtained composite catalyst:

0.5 g of the prepared composite catalyst was placed in a fixed bed of a catalyst evaluation device, and the catalyst flue gas demercuration evaluation was carried out under the conditions of simulated flue gas. The simulated flue gas is composed of O ₂ , CO ₂ , SO ₂ , NO, HCl, N ₂ , the total flow of flue gas is 1L/min, the O ₂ content is 6%, the CO ₂ content is 12%, and the SO ₂ concentration is 400ppm , the concentration of NO is 800ppm, the concentration of Cl ₂ is 50ppm, the flow rate of NH ₃ is 1ml/min, and the rest is N ₂ . 100ml/min N ₂ (as the carrier of mercury vapor), simulated flue gas of zero-valent mercury 20±1μg/m ³ . When the temperature is 180°C and the space velocity is 38000h ^-1 , when the catalyst reaches the stable catalytic stage, the flue gas denitrification rate of the catalyst prepared above is 95.03%, and the oxidation rate of elemental mercury reaches 91.28%. Other conditions remain unchanged, when 1000ppm SO2 is added to the flue gas, the denitrification rate of the catalyst to the flue gas decreases to _90.96 %, and the oxidation efficiency of elemental mercury decreases to 89.07%.

An embodiment of the present invention has been described in detail above, but the content described is only a preferred embodiment of the present invention, and cannot be considered as limiting the implementation scope of the present invention. All equivalent changes and improvements made according to the application scope of the present invention shall still belong to the scope covered by the patent of the present invention.

Claims (10)

1. A copper chloride modified SCR catalyst, characterized in that: the SCR catalyst is a catalyst formed by copper chloride modified metal oxide supported on iron-based pillared attapulgite. 2 . The copper chloride modified SCR catalyst according to claim 1 , wherein the metal oxide is MnO ₂ , CeO ₂ or V ₂ O ₅ . 3. The application of a cupric chloride modified SCR catalyst as claimed in claim 1 or 2 in flue gas demercuration and denitrification. 4. a preparation method of the SCR catalyst modified by cupric chloride as claimed in claim 1 or 2, is characterized in that: comprise the following steps: (1) prepare pure attapulgite; ( ₂ ) Prepare NaOH solution and FeCl3 solution, under the condition of continuous stirring, _NaOH solution is slowly added to FeCl3 solution, the resulting mixed solution is aged under stirring at room temperature; (3) Put pure attapulgite into distilled water and fully stir to prepare the attapulgite suspension, take the mixed solution obtained in step (2) and add it dropwise to the attapulgite suspension, continue stirring and aging; (4) washing with deionized water after suction filtration until no ^Cl- exists, drying, calcining, and grinding to obtain iron-based pillared attapulgite; (5) dissolving manganese nitrate or cerium nitrate in citric acid to form a mixed precursor solution, or dissolving ammonium metavanadate in oxalic acid solution for heating and aging to form a mixed precursor solution; (6) Weighing iron pillar attapulgite and adding to step (5) to obtain mixed precursor body fluid and fully stirring and aging; (7) drying, roasting and grinding to obtain MnO ₂ /Fe-ATP or CeO ₂ /Fe-ATP or V ₂ O ₅ /Fe-ATP catalyst; (8) Weigh CuCl ₂ , add acetone and stir until completely dissolved, slowly add the catalyst obtained in step (7) under constant stirring, stir at room temperature, suction filter, dry, and calcinate to obtain a composite catalyst. 5. the preparation method of the SCR catalyst of a kind of cupric chloride modification according to claim 3 is characterized in that: when step (5) gets manganese nitrate or cerium nitrate to be dissolved in citric acid to form mixed precursor solution, step Add glacial acetic acid to carry out aging in (6), then adjust pH with ammonia water, after reacting to gel, then carry out step (7). 6. the preparation method of the SCR catalyst of a kind of cupric chloride modification according to claim 3 is characterized in that: when step (5) gets ammonium metavanadate to be dissolved in oxalic acid solution heating and aging to form mixed precursor solution , add phosphoric acid as binding agent in step (6). 7. the preparation method of the SCR catalyst of a kind of cupric chloride modification according to claim 3 is characterized in that: the concrete preparation process of step (1) is, preparation takes by weighing attapulgite and puts into distilled water and stirs, Under the action of high shear force, add sodium hexametaphosphate aqueous solution, stir thoroughly, ultrasonically disperse the mixed solution, let it stand, decant the upper suspension, centrifuge the solid obtained by washing with twice distilled water until neutral, dry, and obtain pure Attapulgite. 8. the preparation method of the SCR catalyst of a kind of cupric chloride modification according to claim 3 is characterized in that: the NaOH solution in the described step (2) is 0.4mol/L, and FeCl _The solution is 0.2mol/L L, the stirring aging time is 10h. 9. the preparation method of the SCR catalyst of a kind of cupric chloride modification according to claim 3 is characterized in that: the stirring temperature in the described step (3) is 40 ℃, and stirring time is 24h, and aging time is 12h ; In the step (4), the drying temperature is 90° C., the calcination temperature is 300° C., and the time is 3 hours. 10. The preparation method of a copper chloride modified SCR catalyst according to claim 3, characterized in that: in the step (7), the drying temperature is 80° C., the calcination temperature is 300-400° C., and the time is 3-6h; in the step (8), the drying temperature is 100° C., the drying time is 12 hours, and then put into a muffle furnace for calcination at 300° C. for 4 hours.