CN104399459A - Catalyst for rear-stage three-way catalytic converter - Google Patents
Catalyst for rear-stage three-way catalytic converter Download PDFInfo
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- CN104399459A CN104399459A CN201410604246.XA CN201410604246A CN104399459A CN 104399459 A CN104399459 A CN 104399459A CN 201410604246 A CN201410604246 A CN 201410604246A CN 104399459 A CN104399459 A CN 104399459A
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- catalyst
- rear class
- catalyzing unit
- ternary catalyzing
- noble metal
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Abstract
The invention provides a catalyst for a rear-stage three-way catalytic converter. The catalyst comprises a carrier and an active material. The active material comprises precious metals and a cocatalyst. The precious metals comprise palladium nitrate and rhodium nitrate according to a weight ratio of (2-3): 1. The cocatalyst comprises alumina, cerium-zirconium powder, pseudo-boehmite, deionized water and nitric acid. The catalyst for the rear-stage three-way catalytic converter has a low precious metal use amount, reduces a raw material use cost and retains good tail gas treatment effects.
Description
Technical field
Purifying vehicle exhaust field of the present invention, especially relates to the catalyst being applicable to automobile rear class ternary catalyzing unit.
Background technology
The major pollutants of vehicle exhaust are carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide, at present, mainly utilize the catalyst converter being arranged on automobile exhaust system that carbon monoxide, oxidizing hydrocarbon are become carbon dioxide and water, reduction of nitrogen oxide is become nontoxic nitrogen simultaneously, realize the purification of tail gas.Ternary catalyzing unit, is again catalyst or catalytic cleaner, and this device is positioned in the gas extraction system of automobile, and its effect is the most of exhaust emission reducing engine discharge.Current ternary catalyzing unit can be divided into prime catalyst converter and rear class catalyst converter, and its prime catalyst converter is mainly for the vent gas treatment in engine cold-start stage, and rear class catalyst converter is applied to the vent gas treatment in the thermal starting of cold start-up rear engine; Ternary catalyzing unit is by a metal shell, a net bottom frame and three-way catalyst (containing the precious metal such as platinum, rhodium) composition, can be used for removing HC (hydrocarbon), CO (carbon monoxide) and NOx (oxynitrides) three kinds of major pollutants matter (chemical reaction occurred when so-called ternary refers to this three kinds of compounds of removing).Three-way catalyst is made up of two parts: carrier and be overlying on active catalytic species useful on carrier, and active catalytic species useful selects noble metal usually, as one or more of platinum, palladium and rhodium, adds oxidation material etc. in addition.The conversion efficiency of three-way catalyst is subject to the impact of many factors, topmost factor be exhaust in oxygen concentration and catalytic converter temperature; Due to the generally use of rear class catalyst converter, the kind of the catalyst of current rear class catalyst converter is less, it is generally the rear stage catalyst of general class, if be applied in the automobile catalytic device of small displacement, due to the difference of tail gas harmful substance and huge discharge automobile, the rear stage catalyst of general class effectively for the characteristic of automobile with small output volumn tail gas, can not can cause the waste of catalyst material like this.
Summary of the invention
A kind of catalyst being applied to rear class ternary catalyzing unit that the present invention proposes, and be mainly used in small displacement (1.3L or 1.5L) automobile three-way catalysts.
The technical solution used in the present invention is as follows:
A kind of catalyst being applied to rear class ternary catalyzing unit, comprise carrier and active material, described active material is made up of noble metal and co-catalyst, and described noble metal is made up of palladium nitrate and rhodium nitrate, and described palladium nitrate and the weight proportion of rhodium nitrate are (2 ~ 3): 1; Described co-catalyst is made up of aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid.
Further preferably, the weight proportion of described co-catalyst aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid is 1:0.45:0.09:2.6:0.05.
Further preferably, described palladium nitrate and the weight proportion of rhodium nitrate are 2.3:1.The part by weight of described co-catalyst and noble metal is: (1 ~ 3): (2 ~ 0.1).
Further preferably, described carrier is honeycomb support.
Further preferably, described honeycomb support is 400 order carriers.Described carrier specification is 101.6*90, and showing that the diameter of carrier specification is 101.6mm (millimeter), is highly 90mm (millimeter).
Noble metal all has very high activity to the oxidation of CO, and Pd has high oxidation reaction ability to HC (hydrocarbon oxide), Rh control NO
x(oxynitrides), when the vehicle exhaust of high temperature is by purifier, cleanser in ternary catalyzing unit will strengthen the activity of CO, HC and NOx tri-kinds of gases, it is impelled to carry out certain oxidationreduction chemical reaction, wherein CO is at high temperature oxidized to colourless nontoxic carbon dioxide, HC compound is at high temperature oxidized to water and carbon dioxide, and NOx is reduced into nitrogen and oxygen.The equation of chemical reaction is as follows:
Oxidation reaction:
4HC+5O
2＝4CO
2+2H
2O
2CO+O
2＝2CO
2
Reduction reaction
2NO+2CO＝N
2+2CO
2
10NO+4HC＝5N
2+2H
2O+4CO
2。
In the lean-burn stage, NOx is through processes such as absorption, oxidation and diffusions, and be finally stored in material with the form of Nitrates, in the fuel-rich stage, nitrate or nitrite decompose, and discharge NOx, under the reducing agents such as HC, CO exist, be reduced to eco-friendly nitrogen.
Wherein, cerium oxide has transfer capability between trivalent cerium and quadrivalent cerium oxide, can absorb under lean-burn and fuel-rich condition and discharge oxygen, improves catalyst serviceability; Introduce Zr element and form heat endurance and the oxygen storage capacity that cerium zirconium powder (Ce-Zr, CeZr solid solution) significantly improves cerium oxide.
Boehmite, has another name called monohydrate alumina, false boehmite, can meet oxygen source and react the requirement mixing dispersion, providing a kind of oxygen source of effective abundance.
Nitric acid, for top grade is pure, 100% fuming nitric aicd.
In the application, noble metal adopts palladium nitrate and rhodium nitrate, in the catalyst formulation that the proportioning of palladium nitrate and rhodium nitrate is more current, the use amount of noble metal palladium nitrate and rhodium nitrate is little, the problem of other discharge capacity vehicle exhaust can be different from the one hand for the toxic component (as hydrocarbon and oxynitrides) in automobile with small output volumn tail gas and content, on the other hand, because the overall discharge capacity of automobile with small output volumn tail gas is relatively less, under the condition ensureing vent gas treatment effect, less content noble metal proportioning is adopted to save precious metal material, improve the overall utilization rate of noble metal.
Change use formula and the ratio of co-catalyst simultaneously, the raw materials such as the aluminium oxide wherein adopted, cerium zirconium powder, boehmite and nitric acid, cerium zirconium powder (hydrogen-storing material) usage ratio is higher, the use amount of deionized water reduces, the homogenate (before coating) making co-catalyst raw material be formed like this, have less water content, material concentration is relatively large; After cocatalyst coating, hydrogen-storing material supplements the less use amount of palladium nitrate, forms the balance of compound between co-catalyst and noble metal, provides effective tai-gas clean-up catalyst.
Rear class three-way catalyst provided by the invention, the use amount of noble metal is low, lowers raw material use cost, and catalyst keeps outstanding vent gas treatment effect simultaneously.
Detailed description of the invention
Below in conjunction with the embodiment of the present invention, be clearly and completely described technical scheme of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
Embodiment 1 one kinds is applied to the catalyst of rear class ternary catalyzing unit
Nitric acid is pure nitric acid or fuming nitric aicd, can select the fuming nitric aicd (concentration 100%) of Merck & Co., Inc. (Merck); Cerium zirconium powder can prepare cerium zirconium powder by reverse micelle of microemulsion or coprecipitation, or purchased from chemical company; Boehmite is precipitated or aluminium amalgam preparation method by alkali precipitation, calculation, or purchased from gas chemical company.
Select 400 object honeycomb supports, carrier specification is 101.6*90; During use, first carry out pretreatment: soak carrier with halogen acids (example hydrochloric acid), then with distilled water flushing to neutral, finally dry.
In noble metal, the weight proportion of palladium nitrate and rhodium nitrate is 2.3:1, rhodium nitrate and palladium nitrate is added appropriate water and mixes, then after ball milling, and the coating slurry of obtained catalyst.
In co-catalyst, the weight proportion of aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid is 1:0.45:0.09:2.6:0.05; Each raw material of co-catalyst is mixed, then after ball milling, the slip of obtained co-catalyst.Wherein, the part by weight of co-catalyst and noble metal is 3:1.
When rear class three-way catalyst is prepared, select the preparation method that this area routine is selected; First the slip of co-catalyst is coated on carrier, and in 400 DEG C ~ 600 DEG C roasting temperatures 1 ~ 5 hour, completes the preparation of first step coating; Subsequently, the rhodium nitrate of noble metal and the slip of palladium nitrate are coated on the above-mentioned carrier completing first step coating, 400 DEG C ~ 600 DEG C roastings 1 ~ 5 hour, complete final preparation.
Embodiment 2 one kinds is applied to the catalyst of rear class ternary catalyzing unit
Raw materials is identical with embodiment 1 with method, and difference is: the weight proportion of palladium nitrate and rhodium nitrate is 2:1.The part by weight of co-catalyst and noble metal is 1:2.
Embodiment 3 one kinds is applied to the catalyst of rear class ternary catalyzing unit
Raw materials is identical with embodiment 1 with method, and difference is: the weight proportion of noble metal palladium nitrate and rhodium nitrate is 3:1; The part by weight of co-catalyst and noble metal is 2:0.5.
Embodiment 4 one kinds is applied to the catalyst of rear class ternary catalyzing unit
Raw materials is identical with embodiment 1 with method, and difference is: the part by weight of co-catalyst and noble metal is 1:0.1.
Rear class three-way catalyst prepared by embodiment 1, embodiment 2 and embodiment 3 is applied to the car load emission test of Hua Tai automobile group, car load emission test adopts Tail gas measuring standard to carry out, testing vehicle engine displacement is 1.3L, detects the exhaust emissions of car engine back balance; Emission test result is as shown in table 1;
Table 1
With reference to the testing result of table 1, rear class three-way catalyst prepared by embodiment 1-4 is applied to the vent gas treatment of automobile with small output volumn, the content of discharging tail hydrocarbon in gas, oxynitrides and carbon monoxide reaches discharge standard, and far below the treatment effect of existing discharge standard and existing catalyst.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (6)
1. one kind is applied to the catalyst of rear class ternary catalyzing unit, comprise carrier and active material, described active material is made up of noble metal and co-catalyst, it is characterized in that: described noble metal is made up of palladium nitrate and rhodium nitrate, described palladium nitrate and the weight proportion of rhodium nitrate are (2 ~ 3): 1; Described co-catalyst is made up of aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid.
2. a kind of catalyst being applied to rear class ternary catalyzing unit as claimed in claim 1, is characterized in that: the weight proportion of described co-catalyst aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid is 1:0.45:0.09:2.6:0.05.
3. a kind of catalyst being applied to rear class ternary catalyzing unit as claimed in claim 1, is characterized in that: described co-catalyst and the part by weight of noble metal are: (1 ~ 3): (2 ~ 0.1).
4. a kind of catalyst being applied to rear class ternary catalyzing unit as described in claim 1,2 or 3, is characterized in that: described palladium nitrate and the weight proportion of rhodium nitrate are 2.3:1.
5. a kind of catalyst being applied to rear class ternary catalyzing unit as claimed in claim 1, is characterized in that: described carrier is honeycomb support.
6. a kind of catalyst being applied to rear class ternary catalyzing unit as claimed in claim 5, is characterized in that: described honeycomb support is 400 order carriers.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410604246.XA CN104399459A (en) | 2014-10-31 | 2014-10-31 | Catalyst for rear-stage three-way catalytic converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410604246.XA CN104399459A (en) | 2014-10-31 | 2014-10-31 | Catalyst for rear-stage three-way catalytic converter |
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| CN104399459A true CN104399459A (en) | 2015-03-11 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5013705A (en) * | 1987-10-30 | 1991-05-07 | Degussa Aktiengesellschaft | Platinum-free three-way catalyst |
| CN101224423A (en) * | 2008-02-04 | 2008-07-23 | 北京英泰世纪环境科技有限公司 | Active component block distributed catalyst and preparing method thereof |
| CN101274216A (en) * | 2007-12-29 | 2008-10-01 | 北京英泰世纪环境科技有限公司 | Coaxial radial symmetrical type distribution method of catalyst activity component, preparation and device thereof |
-
2014
- 2014-10-31 CN CN201410604246.XA patent/CN104399459A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5013705A (en) * | 1987-10-30 | 1991-05-07 | Degussa Aktiengesellschaft | Platinum-free three-way catalyst |
| CN101274216A (en) * | 2007-12-29 | 2008-10-01 | 北京英泰世纪环境科技有限公司 | Coaxial radial symmetrical type distribution method of catalyst activity component, preparation and device thereof |
| CN101224423A (en) * | 2008-02-04 | 2008-07-23 | 北京英泰世纪环境科技有限公司 | Active component block distributed catalyst and preparing method thereof |
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Application publication date: 20150311 |