CN104383956A - Catalyst applied to rear three-way catalytic converter - Google Patents
Catalyst applied to rear three-way catalytic converter Download PDFInfo
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- CN104383956A CN104383956A CN201410607986.9A CN201410607986A CN104383956A CN 104383956 A CN104383956 A CN 104383956A CN 201410607986 A CN201410607986 A CN 201410607986A CN 104383956 A CN104383956 A CN 104383956A
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- catalyst
- rear class
- catalytic converter
- nitrate
- catalyzing unit
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Abstract
The invention discloses to a catalyst applied to a rear three-way catalytic converter. The catalyst comprises a carrier and an active material, wherein the active material is composed of precious metal and a cocatalyst. The catalyst is characterized in that the precious metal comprises palladium nitrate and rhodium nitrate; the weight rate of palladium nitrate to rhodium nitrate is 9.3 to 1; the cocatalyst comprises aluminum oxide, ceria-zirconia powder, pseudo-boehmite, deionized water and nitric acid. The rear three-way catalytic converter has excellent purifying effect on gases of the rear catalytic converter based on the characteristics of compounds in the gases of the rear catalytic converter.
Description
Technical field
The present invention relates to vehicle maintenance service field, especially relate to the three-way catalyst of using vehicle rear class catalyst converter.
Background technology
The major pollutants of vehicle exhaust are carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide, utilize the catalyst converter being arranged on gas extraction system carbon monoxide, oxidizing hydrocarbon can be become carbon dioxide and water, reduction of nitrogen oxide is become nontoxic nitrogen simultaneously, realize the purification of tail gas, this catalyst is generally three-way catalyst at present.
Triple mode catalytic converter is the critical piece of automobile engine to exhaust treatment system, mainly comprises bed or the carrier of catalytic conversion reaction, is coated on carrier and has the three-way catalyst etc. promoting chemical conversion reaction.Three-way catalyst is made up of two parts: carrier and the active catalytic species useful be overlying on carrier; Active catalytic species useful selects noble metal usually, as one or more of platinum, palladium and rhodium, adds oxidation material etc. in addition.At present, in order to the difference for exhaust pollutant under engine different condition, triple mode catalytic converter divides prime, rear class catalyst converter, and prime is coupling on enmgine exhaust.Engine exhaust temperature is generally 800-900 DEG C, and after prime catalyst converter, delivery temperature rises to some extent, and tail gas enters rear class catalyst converter subsequently, completes tail gas catalyzed reaction; To purify cold start-up tail gas different from prime catalyst converter, and when the engine burnt gas temperature of discharging is relatively high, oxygen content composition is wherein higher, easily produces more oxynitrides; Producing less harmful exhaust HC, CO, NOx in combustion to effectively control engine, usually needing the output content of three kinds of elements to be balanced; This needs the catalyst being applied in rear class catalyst converter for tail gas compound in rear class catalyst converter.
Summary of the invention
A kind of catalyst being applied to rear class ternary catalyzing unit that the present invention proposes, for the feature of the compound of rear class ternary catalyzing unit tail gas, has outstanding vent gas treatment effect.
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 9.3:1; Described co-catalyst is made up of aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid.
Further preferably, described co-catalyst, the weight proportion of aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid is 1:0.2:0.1:3.5:0.06.
Further preferably, described carrier is honeycomb support.
Further preferably, described honeycomb support is 400 order carriers.The specification of described carrier is 118.4*127, and showing that the diameter of carrier is 118.4mm (millimeter), is highly 127mm (highly).
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.
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), in rear class catalyst converter, oxynitrides content is more, and the mutual ratio of palladium nitrate and rhodium nitrate forms the balance between two kinds of noble metals, can effectively process tail gas compound.Co-catalyst aluminium oxide, cerium zirconium powder, boehmite, deionized water and mutually balance between nitric acid and noble metal, hydrogen-storing material aluminium oxide, cerium zirconium powder, boehmite etc. improve the oxidability of precious metal palladium and rhodium, the oxygen function of storing of the aluminium oxide (hydrogen-storing material) be used alone makes the Rh of its load more easily be in oxidation state, the activity of Rh and the Pd catalysis oxynitrides reduction of oxidation state is lower, and the compound hydrogen-storing material of cerium zirconium powder significantly improves the activity of Rh catalytic reduction oxynitrides; Intend thin water aluminium pore volume comparatively large, be conducive to macromolecular compound to catalyst granules diffusion inside, high-specific surface area is conducive to the dispersion of active metal, improves the reactivity worth of catalyst.Co-catalyst add nitric acid (pure nitric acid), form the dynamic equilibrium of the nitrate anion between catalyst and oxidation product.
Rear class three-way catalyst provided by the invention, for the feature of compound in rear class ternary catalyzing unit tail gas, has outstanding clean-up effect to the tail gas of rear class catalyst converter.
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
Be applied to a catalyst for rear class ternary catalyzing unit, comprise carrier and active material, active material is made up of noble metal and co-catalyst, and wherein, noble metal is by palladium nitrate [Pd (NO
3)
2] and rhodium nitrate [Rh (NO
3)
3] composition, the weight proportion of palladium nitrate and rhodium nitrate is 9.3:1; Wherein, co-catalyst is made up of aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid; Wherein, the weight proportion of aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid is 1:0.2:0.1:3.5:0.06.Wherein, nitric acid selects 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 microemulsion method or coprecipitation, or purchased from company; Boehmite is precipitated or aluminium amalgam preparation method by alkali precipitation, acid, or purchased from company.Wherein, the part by weight of co-catalyst and noble metal is: (1 ~ 3): (2 ~ 0.1).
Three-way catalyst generally adopts two coating structure, and during preparation, mixed by the various raw materials of the noble metal in active material and co-catalyst, be coated on carrier, it is qualified to dry.
Embodiment 2 one kinds is applied to the catalyst of rear class ternary catalyzing unit
In catalyst, active material is in the same manner as in Example 1, and difference is: carrier adopts honeycomb support, and the order number of honeycomb support is 400 orders, and the specification of carrier is 118.4*127.
Carry out purifying property detection to the three-way catalyst provided in embodiment 1 and embodiment 2, wherein adopt car load test (magnificent safe Santa Fe MT) of Hua Tai motor corporation, the discharge capacity of the engine of testing vehicle is 1.8L, and test result is as shown in table 1;
Table 1
With reference in table 1, the rear class three-way catalyst provided in embodiment 1 and embodiment 2 has outstanding purified treatment ability to nitrogen hydroxide, carbon monoxide and hydrocarbon, is especially directed to the purified treatment ability of automobile rear class catalyst converter tail gas.
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 (5)
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, and described palladium nitrate and the weight proportion of rhodium nitrate are 9.3:1; 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, it is characterized in that: described co-catalyst, the weight proportion of aluminium oxide, cerium zirconium powder, boehmite, deionized water and nitric acid is 1:0.2:0.1:3.5:0.06.
3. a kind of catalyst being applied to rear class ternary catalyzing unit as claimed in claim 1 or 2, is characterized in that: described carrier is honeycomb support.
4. a kind of catalyst being applied to rear class ternary catalyzing unit as claimed in claim 3, is characterized in that: described honeycomb support is 400 order carriers.
5. a kind of catalyst being applied to rear class ternary catalyzing unit as claimed in claim 4, is characterized in that: the specification of described carrier is 118.4*127.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410607986.9A CN104383956A (en) | 2014-10-31 | 2014-10-31 | Catalyst applied to rear three-way catalytic converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410607986.9A CN104383956A (en) | 2014-10-31 | 2014-10-31 | Catalyst applied to rear three-way catalytic converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104383956A true CN104383956A (en) | 2015-03-04 |
Family
ID=52601967
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410607986.9A Pending CN104383956A (en) | 2014-10-31 | 2014-10-31 | Catalyst applied to rear three-way catalytic converter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104383956A (en) |
-
2014
- 2014-10-31 CN CN201410607986.9A patent/CN104383956A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| 周庆辉主编: "《现代汽车排放控制技术》", 30 June 2010 * |
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Application publication date: 20150304 |