CN103599813B - A kind of molecular sieve based catalyst for low temperature SCR denitration and preparation method thereof - Google Patents
A kind of molecular sieve based catalyst for low temperature SCR denitration and preparation method thereof Download PDFInfo
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Abstract
The present invention relates to a kind of low-temperature denitration SCR catalyst, the molecular sieve carrier comprising Cu modification and one or more oxides be selected from Ce, Zr, Mn tri-kinds of elements.The present invention's carrier used is the synthesis of cheap templating route, and by the Cu-SSZ-13 molecular sieve of modification, the catalyst in the present invention, within the scope of 100-250 DEG C, reaches 62-100% to the removal effect of nitrogen oxide; Low temperature catalyst in the present invention has good sulfur resistive ability.
Description
Technical field
Molecular sieve art of the present invention, provides a kind of molecular sieve based catalyst for low temperature SCR denitration and preparation method thereof.
Background technology
Along with the continuous growth of energy-consuming, the stationary source based on coal-burning boiler, and internal combustion engine of motor vehicle to be that main moving source discharges the amount of nitrogen oxide (NOx) in air increasing.Nitrogen oxide (NOx) is one of pollution main in atmospheric environment, photochemical fog can be formed, produce acid rain, acid mist, can also damage the ozone layer, huge to environmental hazard, more there is harm to health, can respiratory disease be caused, therefore to control and the pollution of administering nitrogen oxide is the study hotspot of international scope always.
Ammonia selective catalytic reduction (selective catalytic reduction, SCR), because its efficient feature and ripe technical development become the denitration technology of current main flow, and the key problem of this technology is exactly the catalyst of development efficient stable.Being in the catalyst that uses more widely is at present mainly carrier with TiO2, the middle high temperature catalyst of the component such as a certain amount of V2O5, WO3 or MoO3 in load, and general operation temperature is at about 350 DEG C.In the denitrating flue gas for stationary source is applied, in order to meet the requirement of operating temperature, before generally SCR catalyst being arranged in deduster, but because in flue gas, fly ash content is high, easily make beds block, and in flue gas, sulfur content is also higher, easily makes catalyst poisoning inactivation.Component vanadium in addition in catalyst is poisonous, to ecological environment and health unfavorable.For the discharge of nitrogen oxide in exhaust gas from diesel vehicle in moving source, SCR technology and relevant catalyst are that most is promising in this.The domestic denitrating catalyst that there is no large-scale production at present, owing to containing a large amount of oxygen in exhaust gas from diesel vehicle, operation operating mode is also more complicated, have a large amount of NOx in Cold Start to produce, require that the catalyst adopted has wider warm window for these features, traditional vanadium tungsten titanium catalyst and the three-way catalyst of gasoline car all can not meet the purification requirement of NOx in exhaust gas from diesel vehicle.
The focus of current research is exploitation low-temperature SCR technology, and low-temperature SCR technology can reduce denitrating flue gas cost.If low-temperature SCR reaction temperature can be reduced to 100-200 DEG C, after just SCR reactor can being placed on desulfurizing dust-collector, reducing reactor volume and reduce denitration cost.Adopt the catalyst without vanadium, just can solve catalyst poison sex chromosome mosaicism.Therefore, how to develop the low temperature catalyst being applicable to low-temperature zone, realize the high-activity high-selectivity of catalyst in low-temperature range, can determine low temperature SCR denitration technology be widely used.
In order to develop low-temperature SCR technology, researcher has carried out a series of research.Have now been developed a small amount of low-temperature SCR catalyst, MnOx/CeO2 catalyst series prepared by main employing coprecipitation, sol-gel process, infusion process, improve catalyst water resistant sulfur resistive ability by adding auxiliary agent, application number is that the patent application of CN101879452A discloses a kind of preparation method being applied to the compound simple oxide catalyst of low-temperature denitration.This catalyst is based on the oxide of manganese and cerium, active low-temperature denitration catalyst is preferably obtained as auxiliary agent by adding other metal oxides, but simple composite oxide specific area is lower, selective also poor to what react, temperature slightly high (>150 DEG C) can produce a large amount of accessory substances, the selective obvious decline of N2.When entering middle warm area (>250 DEG C), the activity of catalyst starts to decline.
The application of catalyst carrier can increase the specific area of catalyst, pore volume, heat endurance and mechanical strength.Common carrier has TiO2, SiO2, Al2O3, active carbon, zeolite etc.TiO2 has a large amount of acid sites positions, is conducive to the absorption of NH3, but its specific area and pore volume deficiency.There is a large amount of hydroxy groups on Al2O3 surface, be conducive to NO and be oxidized into NO2, reaction rate can be improved, but sulfur resistance is poor, authorize catalyst and preparation method that public number is the national inventing patent of CN100473456C and discloses a kind of SCR denitration for boiler low-temperature fume, take active carbon as carrier, with the oxide of infusion process at Supported Manganese and cerium above.This catalyst uses NACF as carrier, and have larger surface area, to the high adsorption capacity of gaseous material, but its shortcoming is that water resistant ability is poor, and mechanical strength is not enough, and catalyst is easy-formation not.
In sum, still there is certain problem in the research and development of current low-temperature SCR catalyst.Find the catalyst based catalyst carrier be applicable to and need further research and development.
Summary of the invention
The first object of the present invention is to provide a kind of molecular sieve based catalyst for low temperature SCR denitration, adopt the zeolite molecular sieve of specific process synthesis as carrier by using, this kind of carrier has excellent low-temperature SCR activity compared to traditional zeolite molecular sieve carrier, by supported active oxide component, prepare high activity, the low temperature catalyst of high stability; In addition, present invention also offers a kind of preparation method of above-mentioned catalyst.
For realizing the first object, the present invention adopts following technical scheme:
For a molecular sieve based catalyst for low temperature SCR denitration, the molecular sieve carrier comprising Cu modification and one or more oxides be selected from Ce, Zr, Mn tri-kinds of elements.
One or more oxides be selected from Ce, Zr, Mn tri-kinds of elements described in the present invention refer to CeO
2, ZrO
2and MnO
2in one or more, wherein preferred CeO
2-ZrO
2-MnO
2composite oxides.
It should be noted that, although the present invention be in the form of the oxide with consumption to limit molecular sieve based catalyst, but it will be understood by those skilled in the art that, it is only the conventional means of this area herein, do not represent Ce, Zr, the raw material of Mn tri-kinds of elements is confined to oxide, other forms, as containing Ce, Zr, salt (the rear Ce of salt calcining of Mn tri-kinds of elements, Zr, Mn tri-kinds of elements are all exist with the form of oxide) etc., may be used to the raw material preparing molecular sieve based catalyst, those skilled in the art can understand and be selected, the present invention is not particularly limited this.
The molecular sieve carrier of Cu modification of the present invention is obtained by specific process, there is abundant micropore canals structure and the advantage of high-specific surface area, be applied to after in the molecular sieve based catalyst described in the application, make catalyst itself have the advantage of high nitrogen selective.
As one embodiment of the present invention (A method), the molecular sieve carrier of described Cu modification is prepared by following methods:
Be structure directing agent and Tong Yuan with cupric ammine complex, add silicon source, aluminium source and aqueous slkali, molecular sieve is at Na
2o:Al
2o
3: SiO
2: H
2o: cupric ammine complex molar ratio is synthesize the presoma stirred to put into hydrothermal reaction kettle crystallization at 120-150 DEG C in the aqueous precursor gel system of 3.1 ~ 3.8:1.0:10 ~ 35:200:2.0 ~ 3.0, obtains Cu-SSZ-13 by after product filtration, cleaning, drying, roasting.
Wherein, described cupric ammine complex is Cu-TEPA.
Wherein, described silicon source is oxide containing silicon and silicate, is preferably silicate, Ludox, ethyl orthosilicate, deposition of silica and clay, more preferably Ludox; Described aluminium source is trivalent aluminium oxide or aluminate, is preferably sodium metaaluminate, aluminium oxide or aluminium hydroxide; Aqueous slkali is NaOH.Preferably described silicon source is Ludox, described aluminium source be sodium metaaluminate aqueous slkali is NaOH.
As another embodiment of the present invention (B method), the molecular sieve carrier of described Cu modification is prepared by following methods:
Described method makes following raw materials according material contact in water under being included in crystallization condition, obtain molecular sieve crystal:
(1) at least one silicon source;
(2) at least one aluminium source;
(3) at least one alkali metal compound;
(4) as the choline cation of structure directing agent;
(5) hydroxide ion;
By prepared molecular sieve crystal and copper nitrate, copper sulphate or copper acetate solution ion-exchange 4-8h at 40-80 DEG C, then carry out vacuum rotary steam, dry 8-12h at 80-120 DEG C afterwards, 500-600 DEG C of roasting 4-8h in Muffle furnace, obtains the molecular sieve carrier Cu-SSZ-13 of Cu modification.
Concrete grammar is as follows:
A) mixture of preparatory response:
Comprising (1) at least one tetravalence silicon source; (2) at least one trivalent aluminium source; (3) at least one alkali metal compound; (4) as the choline cation of unique structure directing agent (SDA); (5) a large amount of hydroxide ions of strong alkali environment are formed; (6) water for impelling raw mixture to form the presoma of collosol and gel.
B) in the process of heating crystallization, precursor mixture is made to have time enough crystallization to go out to have the SSZ-13 Si-Al molecular sieve of microcellular structure.
C) with copper source, modification is carried out to SSZ-13 Si-Al molecular sieve, obtain the molecular sieve carrier of Cu modification.
Wherein, described tetravalence silicon source includes but not limited to oxide containing silicon and silicate, is preferably, silicate, Ludox, ethyl orthosilicate, deposition of silica and clay, more preferably Ludox.
Wherein, described trivalent aluminium source is trivalent aluminium oxide or aluminate, is preferably sodium metaaluminate, aluminium oxide or aluminium hydroxide.
Described alkali metal compound is compounds containing sodium, and preferred NaOH or sodium chloride, be more preferably NaOH.
Wherein, described choline cation is bursine and Choline Chloride, preferred Choline Chloride.
Preparation method of the present invention, wherein the mol ratio in water and tetravalence silicon source is 3:1 to 15:1.
The mol ratio in tetravalence silicon source and trivalent aluminium source is greater than 3(and silica alumina ratio), be preferably 50 or higher.
In order to optimize overall synthetic method, inventor, on the basis that lot of experiments is studied, is compared to following preferably restriction to the mole dosage of each raw material:
Preferred:
The preparation method of above-mentioned Cu modified molecular screen, get the raw materials ready after terminating, heating crystallization is carried out to reactant mixture, wherein, reaction temperature remains on 100 DEG C-200 DEG C, minimum 4 days of crystallization process, product crystalline solid dries 8-12 hour at 90 DEG C-150 DEG C after washing, and then in Muffle furnace, 500-600 DEG C of calcining obtains SSZ-13 molecular sieve crystal in 6-10 hour.Preferable reaction temperature remains on 140 DEG C, crystallization process 5-35 days, and product crystalline solid dries 10-11 hour at 120 DEG C after washing, and then in Muffle furnace, 550 DEG C of calcinings obtain SSZ-13 molecular sieve crystal in 8 hours.
By prepared molecular sieve crystal and copper nitrate, copper sulphate or copper acetate solution ion-exchange 4-8h at 40-80 DEG C, then carry out vacuum rotary steam, dry 8-12h at 80-120 DEG C afterwards, 500-600 DEG C of roasting 4-8h in Muffle furnace, obtains the molecular sieve carrier Cu-SSZ-13 of Cu modification.
Except the above-mentioned preferred embodiment (effect is better) that the present invention is given, those skilled in the art also can select the SSZ-13 molecular sieve carrier of prior art other Cu modifications disclosed to realize the present invention, prepare the molecular sieve based catalyst for low temperature SCR denitration.
In catalyst of the present invention, when the oxide selected containing one or both elements in Mn, Zr, Ce and molecular sieve carrier Kaolinite Preparation of Catalyst, the mol ratio of Mn, Zr, Ce and Cu is respectively (0-50): (10-15), (0-20): (10-15), (0-50): (10-15).
In catalyst of the present invention, the preferred CeO of described oxide
2-ZrO
2-MnO
2ternary compound oxides, in these composite oxides, the mol ratio of Mn, Zr, Ce and Cu is (30-50): (5-10): (30-50): (10-15).Under this amount ranges, contribute to catalyst low-temperature activity, the raising of nitrogen selective and sulfur resistance.
Further, in described catalyst, the mass ratio of molecular sieve carrier and oxide is the 5-10wt% that 0.3-15, Cu account for molecular sieve supported weight, preferred 4-7wt%.
In addition, present invention also offers the preparation method of above-mentioned molecular screen base low-temperature selective catalytic reduction of ammonia denitrating catalyst, described method specifically comprises:
Step (1): the molecular sieve carrier of preparation Cu modification;
Step (2): one or more oxides in the molecular sieve carrier of Cu modification and Ce, Zr, Mn tri-kinds of elements are at room temperature fully uniformly mixed formation turbid solution with deionized water, the mole dosage of water is 80-120 times of total amount of metal mole;
Step (3): ammonium carbonate is dissolved in deionized water, be made into the sal volatile of 0.5-1.2M, then be added drop-wise in the turbid solution that step (2) configures with the speed of 1-2ml/min, form precipitation, at room temperature continue to stir 1-3 hour, the consumption of added ammonium carbonate is 1.5-2.5 times of slaine mole;
Step (4): the solution system that step (3) obtains is put into supersonic wave cleaning machine ultrasonic immersing 1 ~ 3 hour, filtering and washing;
Step (5): by the filter cake dry 10-24 hour in the baking oven of 80-120 DEG C obtained in step (4), then at 500-600 DEG C roasting 4-8 hour, obtain MOx-Cu/SSZ-13 catalyst, M is one or more in Ce, Zr, Mn tri-kinds of elements.
In order to control to form the more stable catalyst of quality, the present invention has made restriction to the mixing speed described in step (3), is specially 200-300r/min.
Adopt above-mentioned preparation scheme, the present invention can obtain high-quality low-temperature selective catalytic reduction of ammonia denitrating catalyst, it is active that described catalyst has comparatively high/low temperature, and nitrogen selective, molecular sieve based catalyst of the present invention is used within the scope of 100-200 DEG C the purification of nitrogen oxide, its efficiency reaches 62-100%, has good selective in the temperature range of experiment.
Accompanying drawing explanation
Fig. 1 is the XRD spectra of SSZ-13 sieve sample prepared by embodiment 1 (A);
Fig. 2 is the XRD spectra of SSZ-13 sieve sample prepared by embodiment 1 (B);
Fig. 3 is the XRD spectra of SSZ-13 sieve sample prepared by embodiment 2 (A);
Fig. 4 is the XRD spectra of SSZ-13 sieve sample prepared by embodiment 2 (B);
Fig. 5 is catalyst sulfur resistive effect experimental result schematic diagram at different temperatures prepared by embodiment 9;
Fig. 6 is the long period sulfur resistive effect experimental result schematic diagram of catalyst at temperature 140 DEG C prepared by embodiment 9.
Detailed description of the invention
Following examples for illustration of the present invention, but are not used for limiting the scope of the invention.
In following examples, chemical reagent used is commercial goods.
Embodiment 1
0.492 gram of sodium metaaluminate (aluminium source) and 3.6 grams of NaOH are dissolved in 15.8 grams of deionized waters, stir and make it to dissolve completely.2.3 grams of Choline Chlorides will be added in mixture, stir and within 15 minutes, make it to dissolve completely.Slowly 18 grams of LUDOX-AS-40 Ludox (silicon source) are dripped under rapid mixing conditions.
At room temperature stir one hour, last colloid is divided into two parts (A and B), A and B has transferred in teflon-lined stainless steel autoclave respectively, puts into the baking oven of 140 DEG C and keeps 4 days (for A) and 6 days (for B).
Product spends deionized water, collect after filtration, in vacuum drying chamber at 100 DEG C dry 12 hours, then in Muffle furnace, 550 DEG C of calcinings remove structure directing agent in 8 hours, SSZ-13 molecular sieve, the XRD spectra of SSZ-13 molecular sieve that wherein prepared by A, B two groups is shown in Fig. 1 and Fig. 2.
With copper source copper nitrate, modification is carried out to above-mentioned SSZ-13 molecular sieve, obtain the molecular sieve carrier (Cu-SSZ-13 molecular sieve carrier) that copper content is the Cu modification of 5%.
Embodiment 2
0.853 gram of sodium metaaluminate (aluminium source) and 3.0 grams of NaOH are dissolved in 15.8 grams of deionized waters, stir and make it to dissolve completely.1.8 grams of Choline Chlorides will be added in mixture, stir and within 15 minutes, make it to dissolve completely.Slowly 17.25 grams of LUDOX-AS-40 cabosils (silicon source) are dripped under rapid mixing conditions.
At room temperature stir one hour, last colloid is divided into two parts (A and B), A and B has transferred in teflon-lined stainless steel autoclave respectively, puts into the baking oven (for A) of 130 DEG C and 150 DEG C (for B) and keeps 6 days.
Product spends deionized water, collect after filtration, drying 12 hours at vacuum drying chamber 100 DEG C, then calcine at 550 DEG C in Muffle furnace and remove structure directing agent in 8 hours, SSZ-13 molecular sieve, the XRD spectra of SSZ-13 molecular sieve that wherein prepared by A, B two groups is shown in Fig. 3 and Fig. 4.
With copper source copper sulphate, modification is carried out to above-mentioned SSZ-13 molecular sieve, obtain the molecular sieve carrier (Cu-SSZ-13 molecular sieve carrier) that copper content is the Cu modification of 7%.
Embodiment 3
Compared with embodiment 1, distinctive points is only, the concrete selection of each raw material of the present embodiment Middle molecule sieve crystal and mole dosage, than different, are specially:
In the present embodiment, tetravalence silicon source is sodium metasilicate, and trivalent aluminium source is boehmite, and alkali metal compound is NaOH, and hydroxide ion provides with NaOH form.
Embodiment 4
Compared with embodiment 1, distinctive points is only, the concrete selection of each raw material of the present embodiment Middle molecule sieve crystal and mole dosage, than different, are specially:
In the present embodiment, tetravalence silicon source is Ludox, and trivalent aluminium source is aluminium oxide, and alkali metal compound is sodium chloride, and hydroxide ion provides with ammoniacal liquor form.
Embodiment 5
Sodium metaaluminate 0.471g and NaOH 0.250g is dissolved in 10ml deionized water, makes it dissolve completely, then adds 0.841g TEPA, getting 0.998g cupric sulfate pentahydrate joins in above-mentioned solution, stir after 1 hour, be added dropwise to the Ludox of 4ml40wt%, after mixture being stirred 3 hours, put into hydrothermal reaction kettle, react 4 days at 140 DEG C, the product deionized water obtained is washed, and collects after filtration, at vacuum drying chamber 100 DEG C, drying 12 hours, obtains Cu-SSZ-13 molecular sieve.
Embodiment 6
Sodium metaaluminate 0.471g and NaOH 0.250g is dissolved in 10ml deionized water, makes it dissolve completely, then adds 0.841g TEPA, getting 0.998g cupric sulfate pentahydrate joins in above-mentioned solution, stir after 1 hour, be added dropwise to the Ludox of 4ml40wt%, after mixture being stirred 3 hours, put into hydrothermal reaction kettle, react 4 days at 150 DEG C, the product deionized water obtained is washed, and collects after filtration, at vacuum drying chamber 100 DEG C, drying 12 hours, obtains Cu-SSZ-13 molecular sieve.
Embodiment 7
Sodium metaaluminate 0.471g and NaOH 0.250g is dissolved in 10ml deionized water, makes it dissolve completely, then adds 0.841g TEPA, getting 0.998g cupric sulfate pentahydrate joins in above-mentioned solution, stir after 1 hour, be added dropwise to the Ludox of 4ml40wt%, after mixture being stirred 3 hours, put into hydrothermal reaction kettle, react 4 days at 120 DEG C, the product deionized water obtained is washed, and collects after filtration, at vacuum drying chamber 100 DEG C, drying 12 hours, obtains Cu-SSZ-13 molecular sieve.
Embodiment 8
A kind of molecular screen base low-temperature denitration catalyst preparation method is as follows:
1) preparation of carrier
The 4g Cu-SSZ-13 molecular sieve carrier (see the embodiment 5-7) copper content adopting A method to prepare being about 10wt.% and 1M ammonium nitrate solution 400ml were 80 DEG C of stirred in water bath 12 hours, products therefrom suction filtration, washing, drying 12 hours in 100 DEG C of baking ovens, product is put into 550 DEG C of Muffle furnace roastings 8 hours again, obtain the Cu-SSZ-13 carrier that required copper content is about 6.5wt%.
2) load of catalyst
Step one: get the 1.8g molecular sieve carrier and 0.902g cerous nitrate that prepare, 0.600g50wt% manganese nitrate solution, 0.101g zirconium chloride is at room temperature fully uniformly mixed formation turbid solution with the deionized water of 100 times of moles.
Step 2: 0.85g ammonium carbonate is dissolved in deionized water, is made into the sal volatile of 1M, is then added drop-wise in the turbid solution that step one configures with the speed of 1ml/min, forms precipitation, at room temperature continue stirring 2 hours.
Step 3: gained slurries in step 2 are put into supersonic wave cleaning machine ultrasonic immersing 1 hour, then filtering and washing.
Step 4: by the filter cake that obtains in step 3 in the baking oven of 100 DEG C dry 12 hours, then put into Muffle furnace roasting 6 hours at 550 DEG C, obtain MOx-Cu/SSZ-13 catalyst.
The active testing condition of this catalyst is: the NH of the NO of 1000ppm, 1000ppm
3, the O of 6%
2mixing, using argon gas He as carrier gas, loaded catalyst is the 40-60 order particle of 200mg, and adopt fixed bed quartz tube reactor, gas space velocity GHSV hourly is about 50000/h.At 40 DEG C, 60 DEG C, 80 DEG C, 100 DEG C, 120 DEG C, 140 DEG C, 160 DEG C, 200 DEG C, 250 DEG C 9 temperature, the conversion ratio of catalytic reduction of NOx sees attached list one.
Embodiment 9
A kind of molecular screen base low-temperature denitration catalyst preparation method is as follows:
1) preparation of carrier
The 4g Cu-SSZ-13 molecular sieve carrier (see the embodiment 5-7) copper content adopting A method to prepare being about 10wt.% and 1M ammonium nitrate solution 400ml were 80 DEG C of stirred in water bath 12 hours, exchange twice, products therefrom suction filtration, washing, drying 12 hours in 100 DEG C of baking ovens, product is put into 550 DEG C of Muffle furnace roastings 8 hours again, obtain the Cu-SSZ-13 carrier that required copper content is about 5wt%.
2) load of catalyst
Step one: get the 1.2g molecular sieve carrier and 1.809g cerous nitrate that prepare, 1.190g50wt% manganese nitrate solution, 0.198g zirconium chloride is at room temperature fully uniformly mixed formation turbid solution with the deionized water of 80 times of moles.
Step 2: 1.70g ammonium carbonate is dissolved in deionized water, is made into the sal volatile of 0.5M, is then added drop-wise in the turbid solution that step one configures with the speed of 2ml/min, forms precipitation, at room temperature continue stirring 2 hours.
Step 3: gained slurries in step 2 are put into supersonic wave cleaning machine ultrasonic immersing 1 hour, then filtering and washing.
Step 4: by the filter cake that obtains in step 3 in the baking oven of 80 DEG C dry 10 hours, then put into Muffle furnace roasting 8 hours at 500 DEG C, obtain MOx-Cu/SSZ-13 catalyst.
The active testing condition of this catalyst is: the NH3 of the NO of 1000ppm, 1000ppm, the O of 6%
2mixing, using helium He as carrier gas, loaded catalyst is the 40-60 order particle of 200mg, and adopt fixed bed quartz tube reactor, gas space velocity GHSV hourly is ~ 50000-1.At 40 DEG C, 60 DEG C, 80 DEG C, 100 DEG C, 120 DEG C, 140 DEG C, 160 DEG C, 200 DEG C, 250 DEG C nine temperature, the conversion ratio of catalytic reduction of NOx sees attached list one.
This catalyst is carried out to the experiment of SO2 resistance, test condition is: the NH3 of the NO of 1000ppm, 1000ppm, and the O2 mixing of 6%, using helium He as carrier gas, in addition, wherein adds the SO2 of 100ppm in mixing.Loaded catalyst is the 40-60 order particle of 200mg, and adopt fixed bed quartz tube reactor, gas space velocity GHSV hourly is about 50000/h.。In its activity of 40 DEG C ~ 250 DEG C temperature range build-in tests.Its Activity Results is shown in accompanying drawing 5.
As can be seen from Figure 5, SO
2the conversion rate of NOx added for less than 100 DEG C have certain influence, compared to there is no SO
2situation slightly reduce, and when temperature is higher than 100 DEG C, SO
2conversion rate of NOx is not almost affected, when more than 160 DEG C, has certain facilitation on the contrary.
At 140 DEG C, carry out long period stability test to this catalyst, test condition is: the NH of the NO of 1000ppm, 1000ppm
3, the O of 6%
2mixing, using helium He as carrier gas, loaded catalyst is the 40-60 order particle of 200mg, and adopt fixed bed quartz tube reactor, gas space velocity GHSV hourly is ~ 50000
-1.Under fixing probe temperature, successively pass into and remove the SO of 100ppm
2.Its activity change the results are shown in accompanying drawing 6.
Can find out in Fig. 6, reducing slowly has appearred in the activity passing into SO2 rear catalyst, within the testing time conversion ratio of NOx only reduce ~ 2%, and when removal SO2 after activity go up to some extent, illustrate that this catalyst has stronger anti-SO
2ability.
Embodiment 10
A kind of molecular screen base low-temperature denitration catalyst preparation method is as follows:
1) preparation of carrier
Employing B method is prepared 1.9g SSZ-13 molecular sieve (see embodiment 1-4) mix with 0.678g copper nitrate, add 50ml deionized water, stir 12 hours at 80 DEG C, gained slurries vacuum rotary steam is gone out after moisture and obtain product, in 100 DEG C of baking ovens after dry 12 hours, in the Muffle furnace of 550 DEG C, roasting 6 hours, obtains required carrier.
2) load of catalyst
Step one: get the 1.2g molecular sieve carrier and 1.809g cerous nitrate that prepare, 1.190g50Wt% manganese nitrate solution, 0.198g zirconium chloride is at room temperature fully uniformly mixed formation turbid solution with the deionized water of 120 times of moles.
Step 2: 1.70g ammonium carbonate is dissolved in deionized water, is made into the sal volatile of 1.2M, is then added drop-wise in the turbid solution that step one configures with the speed of 1.5ml/min, forms precipitation, at room temperature continue stirring 3 hours.
Step 3: gained slurries in step 2 are put into supersonic wave cleaning machine ultrasonic immersing 3 hours, then filtering and washing.
Step 4: by the filter cake that obtains in step 3 in the baking oven of 120 DEG C dry 10 hours, then put into Muffle furnace roasting 4 hours at 600 DEG C, obtain MOx-Cu/SSZ-13 catalyst.
The active testing condition of this catalyst is: the NH of the NO of 1000ppm, 1000ppm
3, the O of 6%
2mixing, using argon Ar as carrier gas, loaded catalyst is the 40-60 order particle of 200mg, and adopt fixed bed quartz tube reactor, gas space velocity GHSV hourly is about 50000/h.At 40 DEG C, 60 DEG C, 80 DEG C, 100 DEG C, 120 DEG C, 140 DEG C, 160 DEG C, 200 DEG C, 250 DEG C nine temperature, the conversion ratio of catalytic reduction of NOx sees attached list one.
Embodiment 11
A kind of molecular screen base low-temperature denitration catalyst preparation method is as follows:
1) preparation of carrier
Employing B method is prepared 1.9g SSZ-13 molecular sieve (see embodiment 1-4) mix with 0.678g copper nitrate, add 50ml deionized water, stir 12 hours at 80 DEG C, gained slurries vacuum rotary steam is gone out after moisture and obtain product, in 100 DEG C of baking ovens after dry 12 hours, in the Muffle furnace of 550 DEG C, roasting 6 hours, obtains required carrier.
2) load of catalyst
Step one: get the 0.6g molecular sieve carrier and 1.809g cerous nitrate that prepare, 1.190g50wt% manganese nitrate solution, 0.198g zirconium chloride is at room temperature fully uniformly mixed formation turbid solution with the deionized water of 100 times of moles.
Step 2: 1.70g ammonium carbonate is dissolved in deionized water, is made into the sal volatile of 1M, is then added drop-wise in the turbid solution that step one configures with the speed of 1ml/min, forms precipitation, at room temperature continue stirring 2 hours.
Step 3: gained slurries in step 2 are put into supersonic wave cleaning machine ultrasonic immersing 2 hours, then filtering and washing.
Step 4: by the filter cake that obtains in step 3 in the baking oven of 100 DEG C dry 12 hours, then put into Muffle furnace roasting 6 hours at 550 DEG C, obtain MOx-Cu/SSZ-13 catalyst.
The active testing condition of this catalyst is: the NH of the NO of 1000ppm, 1000ppm
3, the O of 6%
2mixing, using helium He as carrier gas, loaded catalyst is the 40-60 order particle of 200mg, and adopt fixed bed quartz tube reactor, gas space velocity GHSV hourly is about 50000/h.At 40 DEG C, 60 DEG C, 80 DEG C, 100 DEG C, 120 DEG C, 140 DEG C, 160 DEG C, 200 DEG C, 250 DEG C nine temperature, the conversion ratio of catalytic reduction of NOx sees attached list one.
Control group
Comparative example 1
The copper content adopting A method to prepare is about the 4g Cu-SSZ-13 molecular sieve of 10Wt.% and 1M ammonium nitrate solution 400ml 80 DEG C of stirred in water bath 12 hours, products therefrom suction filtration, washing, drying 12 hours in 100 DEG C of baking ovens, product is put into 550 DEG C of Muffle furnace roastings 8 hours again, obtain the Cu-SSZ-13 that required copper content is about 6.5Wt%.Catalytic activity test is carried out to this sample.
The active testing condition of this catalyst is: the NH of the NO of 1000ppm, 1000ppm
3, the O of 6%
2mixing, using helium He as carrier gas, loaded catalyst is the 40-60 order particle of 200mg, and adopt fixed bed quartz tube reactor, gas space velocity GHSV hourly is about 50000/h.At 40 DEG C, 60 DEG C, 80 DEG C, 100 DEG C, 120 DEG C, 140 DEG C, 160 DEG C, 200 DEG C, 250 DEG C nine temperature, the conversion ratio of catalytic reduction of NOx sees attached list one.
Comparative example 2
Employing B method is prepared 1.9g SSZ-13 molecular sieve mix with 0.678g copper nitrate, add 50ml deionized water, stir 12 hours at 80 DEG C, gained slurries vacuum rotary steam is gone out after moisture and obtain product, in 100 DEG C of baking ovens after dry 12 hours, roasting 6 hours in the Muffle furnace of 550 DEG C, obtaining required copper content is the Cu-SSZ-13 of 5Wt%.Catalytic activity test is carried out to this sample.
The active testing condition of this catalyst is: the NH of the NO of 1000ppm, 1000ppm
3, the O of 6%
2mixing, using argon Ar as carrier gas, loaded catalyst is the 40-60 order particle of 200mg, and adopt fixed bed quartz tube reactor, gas space velocity GHSV hourly is about 50000/h.At 40 DEG C, 60 DEG C, 80 DEG C, 100 DEG C, 120 DEG C, 140 DEG C, 160 DEG C, 200 DEG C, 250 DEG C nine temperature, the conversion ratio of catalytic reduction of NOx sees attached list one.
Comparative example 3
Step one: get 5.427g cerous nitrate, 3.580g50wt% manganese nitrate solution, 0.583g zirconium chloride is at room temperature fully uniformly mixed formation turbid solution with the deionized water of 100 times of moles.
Step 2: 5.00g ammonium carbonate is dissolved in deionized water, is made into the sal volatile of 1M, is then added drop-wise in the turbid solution that step one configures with the speed of 1ml/min, forms precipitation, at room temperature continue stirring 3 hours.
Step 3: gained slurries in step 2 are put into supersonic wave cleaning machine ultrasonic immersing 3 hours, then filtering and washing.
Step 4: by the filter cake that obtains in step 3 in the baking oven of 100 DEG C dry 12 hours, then put into Muffle furnace roasting 6 hours at 550 DEG C, obtain MnZrCeOx catalyst.Catalytic activity test is carried out to this sample.
The active testing condition of this catalyst is: the NH of the NO of 1000ppm, 1000ppm
3, the O of 6%
2mixing, using argon Ar as carrier gas, loaded catalyst is the 40-60 order particle of 200mg, and adopt fixed bed quartz tube reactor, gas space velocity GHSV hourly is about 50000/h.At 40 DEG C, 60 DEG C, 80 DEG C, 100 DEG C, 120 DEG C, 140 DEG C, 160 DEG C, 200 DEG C, 250 DEG C nine temperature, the conversion ratio of catalytic reduction of NOx sees attached list one.
Subordinate list one
The result of the test recorded in above table shows, low-temperature space and the middle warm area of catalyst of the present invention have greater catalytic performance simultaneously.
Although above the present invention is described in detail with a general description of the specific embodiments, on basis of the present invention, can make some modifications or improvements it, this will be apparent to those skilled in the art.Therefore, these modifications or improvements without departing from theon the basis of the spirit of the present invention, all belong to the scope of protection of present invention.
Claims (12)
1. for a molecular sieve based catalyst for low temperature SCR denitration, it is characterized in that: the molecular sieve carrier comprising Cu modification and one or more oxides be selected from Ce, Zr, Mn tri-kinds of elements; The molecular sieve carrier of described Cu modification is prepared by following methods:
Make following raw materials according material contact in water under crystallization condition, obtain molecular sieve crystal:
(1) at least one silicon source;
(2) at least one aluminium source;
(3) at least one alkali metal compound;
(4) as the choline cation of structure directing agent;
(5) hydroxide ion;
By prepared molecular sieve crystal and copper nitrate, copper sulphate or copper acetate solution ion-exchange 4-8h at 40-80 DEG C, then carry out vacuum rotary steam, dry 8-12h at 80-120 DEG C afterwards, 500-600 DEG C of roasting 4-8h in Muffle furnace, obtains the molecular sieve carrier Cu-SSZ-13 of Cu modification.
2. catalyst according to claim 1, is characterized in that: described one or more oxides be selected from Ce, Zr, Mn tri-kinds of elements are CeO
2, ZrO
2and MnO
2in one or more.
3. catalyst according to claim 2, is characterized in that: described one or more oxides be selected from Ce, Zr, Mn tri-kinds of elements are CeO
2-ZrO
2-MnO
2composite oxides.
4. catalyst according to claim 1, is characterized in that: described silicon source is at least one in oxide containing silicon and silicate; Described aluminium source is trivalent aluminium oxide or aluminate; Described alkali metal compound is NaOH.
5. catalyst according to claim 4, is characterized in that: described silicon source is at least one in silicate, Ludox, ethyl orthosilicate, deposition of silica and clay.
6. catalyst according to claim 4, is characterized in that: described aluminium source is sodium metaaluminate, aluminium oxide or aluminium hydroxide.
7. catalyst according to claim 3, is characterized in that: described CeO
2-ZrO
2-MnO
2composite oxides in, the mol ratio of Mn, Zr, Ce and Cu is followed successively by (30-55): (10-15), (5-10): (10-15), (25-50): (10-15).
8. catalyst according to claim 1, is characterized in that: in described catalyst, and the mass ratio of molecular sieve carrier and oxide is the 5-10wt% that 0.3-12:1, Cu account for molecular sieve supported weight.
9. catalyst according to claim 8, is characterized in that: in described catalyst, and Cu accounts for the 5-7wt% of molecular sieve supported weight.
10. catalyst according to claim 9, is characterized in that: in described catalyst, and Cu accounts for the 6.5wt% of molecular sieve supported weight.
The preparation method of catalyst described in 11. any one of claim 1-10, comprising:
Step (1): the molecular sieve carrier of preparation Cu modification;
The molecular sieve carrier of described Cu modification is prepared by following methods:
Make following raw materials according material contact in water under crystallization condition, obtain molecular sieve crystal:
(a) at least one silicon source;
(b) at least one aluminium source;
(c) at least one alkali metal compound;
D () is as the choline cation of structure directing agent;
(e) hydroxide ion;
By prepared molecular sieve crystal and copper nitrate, copper sulphate or copper acetate solution ion-exchange 4-8h at 40-80 DEG C, then carry out vacuum rotary steam, dry 8-12h at 80-120 DEG C afterwards, 500-600 DEG C of roasting 4-8h in Muffle furnace, obtains the molecular sieve carrier Cu-SSZ-13 of Cu modification;
Step (2): one or more oxides in the molecular sieve carrier of Cu modification and Ce, Zr, Mn tri-kinds of elements are at room temperature fully uniformly mixed formation turbid solution with deionized water, the mole dosage of water is 80-120 times of total amount of metal mole;
Step (3): ammonium carbonate is dissolved in deionized water, be made into the sal volatile of 0.5-1.2M, then be added drop-wise in the turbid solution that step (2) configures with the speed of 1-2ml/min, form precipitation, at room temperature continue to stir 1-3 hour, the consumption of added ammonium carbonate is 1.5-2.5 times of slaine mole;
Step (4): the solution system that step (3) obtains is put into supersonic wave cleaning machine ultrasonic immersing 1 ~ 3 hour, filtering and washing;
Step (5): by the filter cake dry 10-24 hour in the baking oven of 80-120 DEG C obtained in step (4), roasting 4-8 hour at 500-600 DEG C again, obtain MOx-Cu/SSZ-13 catalyst, M is one or more in Ce, Zr, Mn tri-kinds of elements.
12. preparation methods according to claim 11, is characterized in that: in described step (3), mixing speed is 200-300r/min.
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