CN107497465A - Support type low temperature sulfuric-resisting hydrogen ammonium SCR denitration and its preparation method and application - Google Patents

Abstract

The invention belongs to technical field of air pollution control, specially a kind of support type low temperature sulfuric-resisting hydrogen ammonium SCR denitration and its preparation method and application.Sulfuric-resisting hydrogen ammonium SCR denitration of the present invention, its formula are M _x V_1‑x OPO₄/TiO₂, M element is Mo or W；M element and V molal quantity sum are 1；The mass fraction of active component and carrier is：Active component accounts for 1~10 part, and carrier accounts for 90~99 parts.Denitrating catalyst is prepared using infusion process in the present invention, effectively compensate for traditional V₂O₅‑WO₃/TiO₂The defects of light-off temperature is high, and temperature window is narrower, and low-temperature denitration efficiency is low, sulfur resistive water repelling property is weak.Catalyst of the present invention is tolerable to contain 0~3000mg/m simultaneously³SO₂With the nitrogen oxide containing gas of 0~20 vol.% vapor, at 150~300 DEG C and 3,000~100,000h^‑1Under conditions of air speed, denitration efficiency is more than 90%, and can stablize more than 80h, and the discharged nitrous oxides available for the stationary source flue gas such as glass, steel, coking coke oven control.

Description

Loaded low-temperature anti-ammonium bisulfate SCR denitration catalyst and its preparation method and application

technical field

The invention belongs to the technical field of air pollution control, and in particular relates to a loaded low-temperature anti-ammonium bisulfate SCR denitration catalyst and a preparation method and application thereof.

Background technique

Nitrogen oxides NO _x is one of the main sources of global air pollutants (NO, NO ₂ and N ₂ O), and one of the main causes of environmental problems such as photochemical smog, acid rain, smog, and ozone layer destruction. As a result, it has become one of the environmental problems that need to be solved urgently. China's coal-based energy structure has resulted in a large amount of NO _x in the flue gas of thermal power stations, steel, metallurgy, glass, petrochemical, and coking coke ovens. In recent years, China's environmental protection standards have been continuously improved, and the emission control of nitrogen oxides has become more and more stringent. Most of the coal-fired power plants have carried out the transformation of denitrification devices, and applied the most effective flue gas denitrification (deNO _x ) technology in the world. NH ₃ -SCR and commercial high-efficiency catalyst V ₂ O ₅ -WO ₃ /TiO ₂ make the nitrogen oxide emissions in the flue gas of coal-fired power plants basically meet the national emission standards. However, at present, the denitrification technology of industrial boilers such as iron and steel, metallurgy, glass, petrochemical, and coking coke ovens has not been improved, because the flue gas temperature of these industrial boilers is 150-300 ° C, and the flue gas contains more than 300 mg/m ³ SO ₂ and 20 vol.% H ₂ O. At present, the denitrification activity of commercial V ₂ O ₅ -WO ₃ /TiO ₂ catalysts at home and abroad is relatively poor under this condition, because SO ₂ is oxidized by V ₂ O ₅ on the catalyst surface to SO ₃ , SO ₃ and H ₂ O and _NH3 produces substances such as ammonium bisulfate or ammonium sulfate. Ammonium bisulfate or ammonium sulfate at this temperature is a viscous substance that adheres to the surface of the catalyst and covers the active sites, blocking the capillary pores of the catalyst and reducing the denitrification efficiency of the catalyst. Inactivate. There is no mature technology for this kind of low-temperature coal-fired flue gas at home and abroad, which makes the emission reduction situation of flue gas nitrogen oxides in this kind of coal-consuming industry very serious. Therefore, it is of great significance to develop low-temperature anti-ammonium bisulfate catalysts.

The Chinese invention patent with publication number CN102078809 A discloses a Mn-Ti catalyst suitable for low-temperature denitrification at 150-250 °C, but MnO _x is easily poisoned by H ₂ SO ₄ generated by SO ₃ and H ₂ O, and loses its catalytic activity. . Therefore, the development of a low-temperature anti-ammonium bisulfate SCR denitration catalyst has broad application prospects.

Contents of the invention

The object of the present invention is to provide a supported denitrification catalyst with low activation temperature, high catalytic activity and strong anti-water and anti-sulfur performance, and provide its preparation method and application.

The supported low-temperature anti-ammonium bisulfate SCR denitration catalyst provided by the present invention has a general formula of M _x V _{1- x} OPO ₄ /TiO ₂ ; the M element is Mo or W; the sum of the moles of the M element and V is 1; The mass parts of the active component and the carrier are as follows: the active component accounts for 1-10 parts, and the carrier accounts for 90-99 parts.

The present invention also provides a preparation method of the above-mentioned supported low-temperature ammonium bisulfate-resistant SCR denitration catalyst, and the specific steps are as follows:

(1) Add vanadium source and oxalic acid to deionized water, heat in a water bath at 40-90 ℃, and stir magnetically until the solution turns blue;

(2) Add M source to the solution in step (1), stir for 0.5~3 h until completely dissolved;

(3) Add phosphorus source to the solution in step (2), and continue to stir for 0.5~3 h until the reaction is complete;

(4) Add TiO ₂ to the solution in step (3), ultrasonically disperse, stir and evaporate to dryness in a water bath at 60-90°C;

(5) Dry the evaporated samples in a vacuum oven;

(6) Grind the dried sample until there are no particles, and roast it in a muffle furnace to obtain a finished catalyst;

(7) Granulate the finished catalyst and pass it through a 40-60 mesh sieve to obtain an ammonium bisulfate-resistant SCR denitration catalyst.

Preferably, the vanadium source is V ₂ O ₅ or NH ₄ VO ₃ , and the amount of the oxalic acid input is 2 to 4 times that of the vanadium source.

Preferably, the M source is one of Mo or W metal salts.

Preferably, the phosphorus source is one of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate or ammonium phosphate.

Preferably, the vacuum degree of the vacuum drying oven is -0.01~-0.08 MPa, the drying temperature is 80~120 °C, and the holding time is 8~24 h.

Preferably, the calcination temperature is 300-600°C, and the calcination time is 6-12 h.

The advantages of the loaded low-temperature anti-ammonium bisulfate SCR denitrification catalyst of the present invention are: the preparation method is simple, and it can effectively compensate for the low denitrification efficiency of the traditional V ₂ O ₅ -WO ₃ /TiO ₂ catalyst at low temperature, poor sulfur resistance and water resistance, etc. defect.

The catalyst of the present invention can withstand nitrogen oxide flue gas containing 0-3000 mg/m ³ SO ₂ and 0-20 vol.% water vapor at the same time, under the conditions of 150-300 ℃ and 3,000-100,000 h ^-1 space velocity The denitrification efficiency is greater than 90% and can be stabilized for more than 80 hours. It can be used for denitrification treatment of nitrogen oxide emissions from stationary sources such as glass, steel, and coking coke ovens.

detailed description

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. For the experimental methods without specific conditions indicated in the following examples, the conventional conditions or the conditions suggested by the manufacturer are usually followed.

Example 1:

1. Catalyst preparation: Add 0.2 mol ammonium metavanadate (NH4VO ₃ ) and 0.48 mol dihydrate oxalic acid (H ₂ C ₂ O ₄ ·2H ₂ O) to 500 mL deionized water in sequence, and stir at 60°C for 0.5 h to obtain blue solution. Add 0.11 mol of ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O) to the above solution, stir for 0.5 h; add 0.31 mol of H ₃ PO ₄ (85%) to the above solution, continue Stir for 3 h until the reaction is complete; add 500 g of TiO ₂ with a high specific surface area to the solution, ultrasonically disperse, stir and evaporate to dryness at 90°C; transfer the obtained sample to a vacuum drying oven, maintain a vacuum of -0.07 MPa, and maintain a constant temperature of 120°C , dried for 12 h. The solid was ground to no particles and then baked in a muffle furnace at 700 °C for 6 h. Granulate and pass through a 40-60 mesh sieve to obtain a low-temperature load-resistant ammonium bisulfate-resistant SCR catalyst.

2. Catalyst performance test: Take 0.6 g of the catalyst that has been compressed and sieved into a fixed-bed quartz tube reactor, the inner diameter of the quartz tube is 0.4 cm, and the simulated flue gas is composed of NO, NH ₃ , O ₂ and N ₂ , where NO 1500 ppm, NH ₃ 1500 ppm, O ₂ 3vol%, space velocity 80,000 h ^-1 , reaction temperature 150~300 ℃, reaction tail gas was detected online by NO-NO ₂ -NO _x analyzer (Thermo 42 i -HL). Under the test conditions, the denitrification efficiency of the catalyst was stable above 98%.

3. Sulfur resistance and water resistance performance test: SO ₂ and water vapor are introduced into the simulated flue gas: the concentration of SO ₂ is 1000 mg/m ³ , the volume ratio of water vapor is 20 vol.%, and other test conditions remain unchanged. Under this test condition, the denitrification efficiency of the catalyst is still stable above 91%, which proves that the catalyst has strong resistance to ammonium bisulfate.

Example 2:

1. Catalyst preparation: Add 0.2 mol ammonium metavanadate (NH4VO ₃ ) and 0.48 mol dihydrate oxalic acid (H ₂ C ₂ O ₄ ·2H ₂ O) to 500 mL deionized water in sequence, and stir at 60°C for 0.5 h to obtain blue solution. Add 0.067 mol of ammonium metatungstate ((NH ₄ ) ₆ H ₂ W ₁₂ O ₄₀ .nH ₂ O) to the above solution and stir for 0.5 h; add 0.31 mol of H ₃ PO ₄ (85%) to the above solution, Continue to stir for 3 h until the reaction is complete; add 500 g of TiO ₂ with high specific surface area to the solution, ultrasonically disperse, stir and evaporate to dryness at 90°C; transfer the obtained sample to a vacuum drying oven, maintain a vacuum degree of -0.07 MPa, and keep a constant temperature of 120 °C. ℃, dry for 12 h. The solid was ground to no particles and then baked in a muffle furnace at 700 °C for 6 h. Granulate and pass through a 40-60 mesh sieve to obtain a low-temperature load-resistant ammonium bisulfate-resistant SCR catalyst.

2. Catalyst performance test: Take 0.6 g of the catalyst that has been compressed and sieved into a fixed-bed quartz tube reactor, the inner diameter of the quartz tube is 0.4 cm, and the simulated flue gas is composed of NO, NH ₃ , O ₂ and N ₂ , where NO 1500 ppm, NH ₃ 1500 ppm, O ₂ 3vol%, space velocity 80,000 h ^-1 , reaction temperature 150~300 ℃, reaction tail gas was detected online by NO-NO ₂ -NO _x analyzer (Thermo 42 i -HL). Under the test conditions, the denitrification efficiency of the catalyst was stable at 96%.

3. Sulfur resistance and water resistance performance test: SO ₂ and water vapor are introduced into the simulated flue gas: the concentration of SO ₂ is 1000 mg/m ³ , the volume ratio of water vapor is 20 vol.%, and other test conditions remain unchanged. Under this test condition, the denitrification efficiency of the catalyst is still stable above 90%, which proves that the catalyst has strong resistance to ammonium bisulfate.

Example 3:

1. Preparation of catalyst: Add 0.1 mol of vanadium pentoxide (V ₂ O ₅ ) and 0.48 mol of oxalic acid dihydrate (H ₂ C ₂ O ₄ 2H ₂ O) to 500 mL of deionized water in sequence, and stir at 60°C for 0.5 h , an orange suspension was obtained. Add 0.11 mol ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O) to the above suspension, stir for 0.5 h; add 0.31 mol H ₃ PO ₄ (85%) to the above solution , continue to stir for 3 h until the reaction is complete; add 500 g of TiO ₂ with high specific surface area to the solution, ultrasonically disperse, stir and evaporate to dryness at 90°C; transfer the obtained sample to a vacuum drying oven, maintain a vacuum degree of -0.07 MPa, and 120 ℃, dry for 12h. The solid was ground to no particles and then baked in a muffle furnace at 700 °C for 6 h. Granulate and pass through a 40-60 mesh sieve to obtain a low-temperature load-resistant ammonium bisulfate-resistant SCR catalyst.

2. Catalyst performance test: Take 0.6 g of the catalyst that has been compressed and sieved into a fixed-bed quartz tube reactor, the inner diameter of the quartz tube is 0.4 cm, and the simulated flue gas is composed of NO, NH ₃ , O ₂ and N ₂ , where NO 1500 ppm, NH ₃ 1500 ppm, O ₂ 3vol%, space velocity 80,000 h ^-1 , reaction temperature 150~300 ℃, reaction tail gas was detected online by NO-NO ₂ -NO _x analyzer (Thermo 42 i -HL). Under the test conditions, the denitrification efficiency of the catalyst was stable at 98%.

3. Sulfur resistance and water resistance performance test: SO ₂ and water vapor are introduced into the simulated flue gas: the concentration of SO ₂ is 1000 mg/m ³ , the volume ratio of water vapor is 20 vol.%, and other test conditions remain unchanged. Under this test condition, the denitrification efficiency of the catalyst is still stable above 93%, which proves that the catalyst has strong resistance to ammonium bisulfate.

Example 4:

1. Preparation of catalyst: Add 0.1 mol of vanadium pentoxide (V ₂ O ₅ ) and 0.48 mol of oxalic acid dihydrate (H ₂ C ₂ O ₄ 2H ₂ O) to 500 mL of deionized water in sequence, and stir at 60°C for 0.5 h , an orange suspension was obtained. Add 0.067 mol of ammonium metatungstate ((NH ₄ ) ₆ H ₂ W ₁₂ O ₄₀ .nH ₂ O) to the above suspension and stir for 0.5 h; add 0.31 mol of H ₃ PO ₄ (85 %), continue to stir for 3 h until the reaction is complete; add 500 g of TiO ₂ with high specific surface area to the solution, ultrasonically disperse, stir and evaporate to dryness at 90°C; transfer the obtained sample to a vacuum drying oven, and maintain a vacuum degree of -0.07 MPa , constant temperature 120 ℃, drying 12h. The solid was ground to no particles and then baked in a muffle furnace at 700 °C for 6 h. Granulate and pass through a 40-60 mesh sieve to obtain a low-temperature load-resistant ammonium bisulfate-resistant SCR catalyst.

2. Catalyst performance test: Take 0.6 g of the catalyst that has been compressed and sieved into a fixed-bed quartz tube reactor, the inner diameter of the quartz tube is 0.4 cm, and the simulated flue gas is composed of NO, NH ₃ , O ₂ and N ₂ , where NO 1500 ppm, NH ₃ 1500 ppm, O ₂ 3vol%, space velocity 80,000 h ^-1 , reaction temperature 150~300 ℃, reaction tail gas was detected online by NO-NO ₂ -NO _x analyzer (Thermo 42 i -HL). Under the test conditions, the denitrification efficiency of the catalyst was stable at 98%.

3. Sulfur resistance and water resistance performance test: SO ₂ and water vapor are introduced into the simulated flue gas: the concentration of SO ₂ is 1000 mg/m ³ , the volume ratio of water vapor is 20 vol.%, and other test conditions remain unchanged. Under this test condition, the denitrification efficiency of the catalyst is still stable above 91%, which proves that the catalyst has strong resistance to ammonium bisulfate.

Claims (8)

1. A supported low-temperature anti-ammonium bisulfate SCR denitration catalyst is characterized in that its general formula is M _x V _{1- x} OPO ₄ /TiO ₂ ; the M element is Mo or W; the molar ratio between the M element and V The sum is 1; the mass parts of the active component and the carrier are: the active component accounts for 1-10 parts, and the carrier accounts for 90-99 parts. 2. the preparation method of anti-ammonium bisulfate SCR denitration catalyst as claimed in claim 1, is characterized in that, concrete steps are as follows: (1) Add vanadium source and oxalic acid to deionized water, heat in a water bath at 40-90 ℃, and stir magnetically until the solution turns blue; (2) Add M source to the solution in step (1), stir for 0.5~3 h until completely dissolved; (3) Add phosphorus source to the solution in step (2), and continue to stir for 0.5~3 h until the reaction is complete; (4) Add TiO ₂ to the solution in step (3), ultrasonically disperse, stir and evaporate to dryness in a water bath at 60-90°C; (5) Dry the evaporated samples in a vacuum oven; (6) Grind the dried sample until there are no particles, and roast it in a muffle furnace to obtain a finished catalyst; (7) Granulate the finished catalyst and pass through a 40-60 mesh sieve to obtain an ammonium bisulfate-resistant SCR catalyst. 3. The preparation method of ammonium bisulfate-resistant SCR denitration catalyst according to claim 2, characterized in that, the vanadium source described in step (1) is V ₂ O ₅ or NH ₄ VO ₃ , and the oxalic acid input The amount of the substance is 2 to 4 times the amount of the vanadium source input substance. 4. The method for preparing an ammonium bisulfate-resistant SCR catalyst according to claim 2, characterized in that: the M source described in step (2) is one of Mo or W metal salts. 5. The preparation method of ammonium bisulfate-resistant SCR denitration catalyst according to claim 2, characterized in that: the phosphorus source described in step (3) is phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate or ammonium phosphate kind of. 6. The preparation method of the anti-ammonium bisulfate SCR denitration catalyst according to claim 2, characterized in that: the vacuum degree of the vacuum drying oven described in step (5) is -0.01~-0.08 MPa, and the drying temperature is 80~ 120 ℃, the maintenance time is 8~24 hours. 7. The preparation method of ammonium bisulfate-resistant SCR denitration catalyst according to claim 2, characterized in that the calcination temperature in step (6) is 300-600 °C, and the calcination time is 6-12 h. 8. The application of the anti-ammonium bisulfate SCR denitration catalyst as claimed in claim 1 in the nitrogen oxide emission control of stationary source flue gas.