Summary of the invention
A kind of exhaust gas from diesel vehicle purification of nitrogen oxides of the present invention is to overcome the existing weak point of existing catalyst by the preparation method's of selective catalytic reduction catalysts object, develop a kind of within the scope of wider applied temps, have high catalytic activity for removing new catalyst of exhaust gas from diesel vehicle nitrogen oxide and preparation method thereof.
The invention provides a kind of exhaust gas from diesel vehicle purification of nitrogen oxides selective catalytic reduction catalysts:
A NOx SCR molecular sieve catalyst, consists of: (10%~30%) CeO
2-M+ (90%~70%) Fe/ZSM-5, wherein M is TiO
2or WO
3, CeO
2mass ratio=3 of/M: 1~1: 1; The SiO of molecular sieve ZSM-5
2/ Al
2o
3=15~150.
The preparation method of NOx SCR molecular sieve catalyst of the present invention, step is as follows:
1) get solubility cerium salt, obtained aqueous solution, concentration is 0.5~1.5mol/L, is first aqueous solution; The soluble-salt obtained aqueous solution of titanium or tungsten, concentration is 0.5~1.5mol/L, is second aqueous solution;
2) under stirring, in first aqueous solution and second aqueous solution, be added into respectively alkali precipitation agent, making pH value is 8~10, and to add polyethylene glycol be thickener, fully stirs 10~30min;
3) by step 2) standing 30~120min under the first solution of obtaining respectively and the second aqueous solution gained suspension room temperature, after 60-80 ℃ of ageing 1~3h, evenly mixes two kinds of suspensions under stirring;
4) to step 3) gained mixing suspension is at 60-80 ℃ of secondary ageing 10~16h;
5) by step 4) suspension after ageing carries out vacuum filtration, obtains filtrate washing to neutral, and product is dried 10~15h at 100~140 ℃ successively, 280~320 ℃ of preroast 0.5~1h, 450~550 ℃ of roasting 1~3h, obtain CeO
2-M.
6) get solubility ammonium salt, obtained aqueous solution, concentration is 0.2~1.5mol/L;
7) to step 6) gained solution, adding ammoniacal liquor to regulate pH value is 3~4, adds HZSM-5,70-90 ℃ is stirred 3~10h;
8) by step 7) suspension carry out vacuum filtration, obtain filtrate washing to neutral, product is dried 12~18h at 100~140 ℃, obtains NH
4zSM-5;
9) get soluble ferric iron salt, obtained aqueous solution, concentration is 0.5~1.5mol/L;
10) to step 9) gained solution, adding ammoniacal liquor to regulate pH value is 3~4, adds NH
4zSM-5,70-90 ℃ is stirred 3~30h;
11) by step 10) suspension carry out vacuum filtration, obtain filtrate washing to neutral, product is dried 12~18h at 100~140 ℃ successively, 450~550 ℃ of roasting 1~3h, obtain FeZSM-5;
12) get FeZSM-5 prepared by step (11), be added to the water, stir, add binding agent;
13) blank cordierite honeycomb ceramic carrier is immersed in slurry prepared by step (12) to dry 1~3h at 100~150 ℃ successively after taking-up, 450~550 ℃ of roasting 2~4h.
14) get CeO prepared by step (5)
2-M, is added to the water, and stirs, and adds binding agent;
15) by step 13) in the slurry prepared in step (14) of the carrier impregnation prepared, after taking-up at 100~150 ℃ dry 1~3h, 450~550 ℃ of roasting 2~4h.
The molar concentration of described alkali precipitation agent is 3.5~4.5mol/L, and the addition of polyethylene glycol is 1~10% of alkaline precipitating agent weight;
Described solubility cerium salt is cerous nitrate, cerous sulfate or cerous chlorate;
Described solubility titanium salt is titanyl sulfate, titanium tetrachloride or butyl titanate;
Described soluble tungsten salt is ammonium tungstate;
Described alkaline precipitating agent is ammoniacal liquor or carbonic hydroammonium;
Described solubility ammonium salt is ammonium nitrate, ammonium sulfate or carbonic hydroammonium;
Described soluble ferric iron salt is ferric nitrate, ferric sulfate or iron chloride;
Described binding agent is one or more in alumina sol, Ludox or acetic acid zirconium.
The preparation method who removes the selective catalytic reduction catalysts of exhaust gas from diesel vehicle nitrogen oxide of the present invention, take solubility cerium salt and titanium salt (or tungsten salt) is raw material, alkali is coprecipitator, polyethylene glycol is thickener, according to the molar concentration rate ratio of 3: 1~1: 1 preparation of Ce and Ti or W ion, obtains CeO
2-M.Take molecular sieve HZSM-5 as raw material, and solubility ammonium salt is ammonium source, and ion-exchange makes NH
4zSM-5.Take soluble ferric iron salt as raw material, and ion-exchange makes FeZSM-5.One or more of take in alumina sol, Ludox or acetic acid zirconium are binding agent, first apply FeZSM-5 on cordierite honeycomb ceramic carrier, dry roasting; Be coated with and be covered with CeO again
2-M, dries roasting.
After cordierite honeycomb ceramic carrier floods and takes out, repeated impregnations and dry, until reach the required coated weight of carrier;
Exhaust gas from diesel vehicle purification of nitrogen oxides provided by the invention has the following advantages with selective catalytic reduction catalysts tool: wide active temperature windows (conversion ratio is greater than 80%), and in 190-600 ℃ of temperature range, can realize efficient catalytic and remove nitrogen oxide.Meanwhile, accessory substance N
2o is less.There is good anti-hydrocarbon and SO
2poisoning capability, at steam or SO
2exist under atmosphere, SCR activity keeping is more than 80%.Can be applicable to NO in exhaust gas from diesel vehicle
ximprovement, preparation process is simple, easy to operate, with low cost, can meet and reach the standard of existing motor vehicle tail-gas purifying and the needs of actual production.
The specific embodiment
Below in conjunction with embodiment, technical characterictic of the present invention is described further:
Embodiment 1
Get 21.7g cerous nitrate, be dissolved in (0.5mol/L) in 100mL ionized water, under rapid stirring, use 4mol/L NH
3h
2o precipitates, and regulating pH is 8, adds polyethylene glycol 0.3g, fully stirs 10min, the standing 1h of room temperature, 60 ℃ of ageing 3h; Get titanyl sulfate 8g, be dissolved in (0.5mol/L) in 100mL deionized water, under vigorous stirring, use 4mol/LNH
3h
2o precipitates, and titration end-point is that pH is 9, adds polyethylene glycol 0.2g, fully stirs 30min, the standing 1h of room temperature, 80 ℃ of ageing 3h; By two kinds of suspensions (according to CeO
2/ TiO
2(mass ratio)=3/1) stir fully and mix, and carry out ageing for the second time at 60 ℃, digestion time is 12h.Use vacuum filtration, obtain sediment, and use deionized water that sediment is washed to filtrate and is neutral, afterwards 100 ℃ of gained filter cakes are dried to 10h, 280 ℃ of preroast 0.5h, 450 ℃ of roasting 3h obtain CeO
2-TiO
2powder sample;
Get 8g ammonium nitrate and be dissolved in (0.5mol/L) in 100mL deionized water, adding ammoniacal liquor to regulate pH value is 3, adds 20gHZSM-5 (SiO
2/ Al
2o
3=15), 70 ℃ are stirred 10h; The suspension obtaining is carried out to vacuum filtration, obtain filtrate washing to neutral, product is dried 12h at 100 ℃, obtains NH
4zSM-5; Get 20.2g ferric nitrate and be dissolved in (0.5mol/L) in 100mL deionized water, adding ammoniacal liquor to regulate pH value is 3, adds 10g NH
4zSM-5,90 ℃ are stirred 3h; The suspension obtaining is carried out to vacuum filtration, obtain filtrate washing to neutral, product is dried 12h at 100 ℃, and 550 ℃ of roasting 1h, obtain FeZSM-5 powder sample;
The FeZSM-5 powder sample that adds 20g to make in 1L deionized water, stirs, and adds the binding agent alumina sol of mixed solution quality 20%, and stirring at room 0.5h, obtains slurry one.
Blank cordierite honeycomb ceramic carrier is immersed in slurry one, takes out the raffinate in after-blow clear opening road, at 100 ℃ of dry 1.5h.Then at 450 ℃ of roasting 2h, obtain honeycomb catalyst 1.
The CeO that adds 8g to make in 500mL deionized water
2-TiO
2powder sample, stirs, and adds the binding agent alumina sol of mixed solution quality 20%, and stirring at room 0.5h, obtains slurry two.
Honeycomb catalyst 1 is immersed in slurry two, takes out the raffinate in after-blow clear opening road, at 100 ℃ of dry 1.5h.Then at 450 ℃ of roasting 2h, the catalyst of acquisition is labeled as 1#, wherein CeO
2-TiO
2account for 10%, FeZSM-5 and account for 90%.
Get respectively the 60.60g cerous sulfate preparation 100ml aqueous solution (1.5mol/L) or the 24.65g cerous chlorate preparation 100ml aqueous solution (1.0mol/L) as cerium precursor salt, titanium salt is constant, according to CeO
2/ TiO
2mix (mass ratio)=2/1, HZSM-5 (SiO
2/ Al
2o
3=90), preparation method is constant, makes catalyst 2# and 3#, wherein CeO
2-TiO
2account for 20%, FeZSM-5 and account for 80%.
Cerium precursor salt is constant, gets respectively the 18.97g titanium tetrachloride preparation 100ml aqueous solution (1.0mol/L) or the 51.045g butyl titanate preparation 100ml aqueous solution (1.5mol/L) as titanium precursor body salt, according to CeO
2/ TiO
2mix (mass ratio)=1/1, HZSM-5 (SiO
2/ Al
2o
3=150), preparation method is constant, makes catalyst 4# and 5#, wherein CeO
2-TiO
2account for 30%, FeZSM-5 and account for 70%.
Catalyst 1#, the 2#, 3#, 4# and the 5# that handle well (Φ (20~40) * (20~40mm)) honeycomb is positioned in tubular reactor, and experiment condition is: NO 500ppm, NH
3500ppm, O
25%, N
2for Balance Air, total gas flow rate is 1500ml/min, air speed 30,000h
-1, reaction temperature interval is from 100 ℃ to 650 ℃.Online NO, the NH of detecting
3, NO
2, N
2o concentration.In 190~600 ℃ of temperature ranges, NOx conversion ratio is more than 80%, and particularly, in 210~570 ℃ of temperature ranges, NOx conversion ratio reaches more than 90%.In investigating temperature range, selectively reach 99%, N
2o concentration is less than 15ppm.
Embodiment 2
Get 32.55g cerous nitrate and be dissolved in (0.75mol/L) in 100mL deionized water, use 4mol/L carbonic hydroammonium to precipitate under rapid stirring, regulating pH is 10, adds polyethylene glycol 0.5g, fully stirs 30min, the standing 1h of room temperature, 80 ℃ of ageing 3h; Get ammonium tungstate 149.25g, be dissolved in (0.5mol/L) in 100mL deionized water, under vigorous stirring, use 4mol/LNH
3h
2o precipitates, and titration end-point is that pH is 9, adds polyethylene glycol 0.2g, fully stirs 30min, the standing 1h of room temperature, 60 ℃ of ageing 3h; By two kinds of suspensions according to CeO
2/ WO
3(mass ratio)=3/1 is stirred fully and is mixed, and carries out ageing for the second time at 80 ℃, and digestion time is 12h.Use vacuum filtration, obtain sediment, and use deionized water that sediment is washed to filtrate and is neutral, afterwards 140 ℃ of gained filter cakes are dried to 15h, 320 ℃ of preroast 1h, 550 ℃ of roasting 1h obtain CeO
2-WO
3powder sample;
Get 2.64g ammonium sulfate and be dissolved in (0.2mol/L) in 100mL deionized water, adding ammoniacal liquor to regulate pH value is 4, adds 20gHZSM-5 (SiO
2/ Al
2o
3=15), 90 ℃ are stirred 3h; The suspension obtaining is carried out to vacuum filtration, obtain filtrate washing to neutral, product is dried 12h at 100 ℃, obtains NH
4zSM-5; Get 40g ferric sulfate solution (1mol/L) in 100mL deionized water, adding ammoniacal liquor to regulate pH value is 4, adds 10g NH
4zSM-5,70 ℃ are stirred 10h; The suspension obtaining is carried out to vacuum filtration, obtain filtrate washing to neutral, product is dried 18h at 140 ℃, and 450 ℃ of roasting 3h, obtain FeZSM-5 powder sample;
The FeZSM-5 powder sample that adds 20g to make in 1L deionized water, stirs, and adds the binding agent alumina sol of mixed solution quality 20%, and stirring at room 0.5h, obtains slurry one.
Blank cordierite honeycomb ceramic carrier is immersed in slurry one, takes out the raffinate in after-blow clear opening road, at 100 ℃ of dry 1.5h.Then at 450 ℃ of roasting 2h, obtain honeycomb catalyst 1.
The CeO that adds 8g to make in 500mL deionized water
2-WO
3powder sample, stirs, and adds the adhesive silicon sol of mixed solution quality 20%, and stirring at room 0.5h obtains slurry two.
Honeycomb catalyst 1 is immersed in slurry two, takes out the raffinate in after-blow clear opening road, at 100 ℃ of dry 1.5h.Then at 450 ℃ of roasting 2h, the catalyst of acquisition is labeled as 6#, wherein CeO
2-WO
3account for 10%, FeZSM-5 and account for 90%.
Get ammonium tungstate 298.50g preparation 100ml solution (1.0mol/L), according to CeO
2/ WO
3mix (mass ratio)=2/1, gets 11.86g carbonic hydroammonium as solubility ammonium salt (1.5mol/L), HZSM-5 (SiO
2/ Al
2o
3=90), other raw materials and preparation method are constant, and the catalyst of acquisition is labeled as 7#, wherein CeO
2-WO
3account for 20%, FeZSM-5 and account for 80%.
Get ammonium tungstate 447.75g preparation 100ml solution (1.5mol/L), according to CeO
2/ WO
3mix (mass ratio)=1/1, gets 40.55g iron chloride as soluble ferric iron salt (1.5mol/L), HZSM-5 (SiO
2/ Al
2o
3=150), other raw materials and preparation method are constant, and the catalyst of acquisition is labeled as 8#, wherein CeO
2-WO
3account for 30%, FeZSM-5 and account for 70%.
Using three kinds of materials of acetic acid zirconium or alumina sol, Ludox and acetic acid zirconium (mass ratio 1: 1: 1) respectively as binding agent, and the catalyst of acquisition is labeled as 8# and 9#.
By the catalyst 6# handling well, 7#, 8# and 9# (Φ (20~40) * (20~40mm)) honeycomb is positioned in tubular reactor, and experiment condition is: NO 500ppm, NH
3500ppm, O
25%, N
2for Balance Air, total gas flow rate is 1500ml/min, air speed 30,000h
-1, reaction temperature interval is from 100 ℃ to 650 ℃.Online NO, the NH of detecting
3, NO
2, N
2o concentration.In 190~600 ℃ of temperature ranges, NOx conversion ratio is more than 80%, and particularly, in 210~570 ℃ of temperature ranges, NOx conversion ratio reaches more than 90%.In investigating temperature range, selectively reach 99%, N
2o concentration is less than 15ppm.
Embodiment 3
Catalyst 2#, 5# and 8# are at 10%H respectively
2o, 800 ℃, air speed 30000h
-1, hydrothermal aging 48h.The catalyst of respectively hydrothermal aging being handled well (Φ (20~40) * (20~40mm)) honeycomb is positioned in tubular reactor, and experiment condition is with embodiment 1.In 250~480 ℃ of temperature ranges, NOx conversion ratio is more than 80%.In investigating temperature range, selectively reach 99%, N
2o concentration is less than 20ppm.
Embodiment 4
Catalyst 1#, 3# and 6# are at 40ppmSO respectively
2+ 14%O
2+ 5%CO
2+ 4.5%H
2o, 300 ℃, air speed 50000h
-1, hydrothermal aging 48h.Respectively good catalyst (Φ (20~40) * (20~40mm)) honeycomb of sulphur burin-in process is positioned in tubular reactor, experiment condition is with embodiment 1.In 200~500 ℃ of temperature ranges, NOx conversion ratio is more than 80%.In investigating temperature range, selectively reach 99%, N
2o concentration is less than 20ppm.
Embodiment 5
Catalyst 4#, 7# and 6# are at 350ppm NO+350ppm NH respectively
3+ 14%O
2+ 50ppmC
6h
6+ 30ppmC
3h
6+ 2%H
2o, N
2for Balance Air, total gas flow rate is 1500ml/min, air speed 50,000h
-1, reaction temperature interval is from 100 ℃ to 650 ℃.Online NO, the NH of detecting
3, NO
2, N
2o concentration.In 220~550 ℃ of temperature ranges, NOx conversion ratio is more than 80%, and particularly, in 260~500 ℃ of temperature ranges, NOx conversion ratio reaches more than 90%.In investigating temperature range, selectively reach 99%, N
2o concentration is less than 15ppm.