CN201027559Y

CN201027559Y - Catalyzing body used for vent gas purification of internal combustion engine

Info

Publication number: CN201027559Y
Application number: CNU2007201417629U
Authority: CN
Inventors: 刘光文
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-03-22
Filing date: 2007-03-22
Publication date: 2008-02-27
Anticipated expiration: 2017-03-22

Abstract

The utility model discloses a tail-gas purification catalyst of internal combustion engine. At present, the mechanism of action of the catalyst is to catalyze and transform hazardous substance in tail-gas with the effect of noble metal and gamma-aluminium sesquioxide; the prior preparation technology makes the dosage of the noble metal account for more than four percent of the catalyst weight and the applied proportion of the noble metal is unreasonable, leading to the high cost of applied catalyst. The utility model is formed by matching and coating a first spumous carrier, rare earth oxides and the noble metal; when the utility model is applied to purify tail-gas of automobiles, the dosage of noble metal can be drastically reduced to 0.01g to 0.35g per liter of catalyst; the catalyzing and conversion efficiency of tail-gas can reach 97 percent; when the utility model is applied to purify tail-gas of automobiles, the automobile emission standard can reach European Union IV Emissions Standard; the pollution index can be controlled with 0.46 percent of HC, 1.5 percent of CO, 3.5 percent of Nox and less than 0.02 percent of PM.

Description

A kind of catalytic body that is used for purifying internal combustion engine tail gas

Technical field

The utility model relates to a kind of catalytic body, this catalytic body is mainly used in purifying internal combustion engine tail gas, also can be applicable to industrial waste gas purifying and air purification.

Background technique

Environmental protection is vital for modern society, and vehicle exhaust has become the arch-criminal of city environmental pollution, and administering automobile exhaust pollution is the most important thing of city environmental protection.The harmful substances that mainly contains in the vehicle exhaust is exhaust gas particle, sulphide, carbon monoxide, hydrocarbon, nitrogen oxide, one of main method that the method that these compounds are played good catalyzed conversion effect is promptly administered automobile exhaust pollution is exactly by catalytic body is installed in baffler, the harmful matter in the tail gas is converted into innoxious substance discharges.At present, the preparation technology of catalytic body applies γ-aluminium sesquioxide exactly again as second carrier on first carrier, apply noble coatings again on γ-alumina carrier.Utilize the carrier function of precious metal and γ-aluminium sesquioxide, the harmful matter in the waste gas is carried out catalyzed conversion, but can exist noticeable three problems like this.One is that the first carrier structure shape and void density are bigger to the catalytic conversion efficiency influence, because the first present carrier nearly all is straight-through netted, specific surface area is less like this, and general specific surface area does not reach 20-40 square metre/milliliter requirement; The 2nd, at high temperature γ-alumina carrier can present toxic state and reduce working life to α-aluminium sesquioxide conversion; Three are to use precious metal as the Preparation of Catalyst catalytic body, and its cost is too expensive.A kind of good catalytic body must be to be made of carrier and scientific and reasonable coating, and good catalytic body shows that existing conversion ratio height has the advantage of rational cost.And the preparation technology of catalytic body is difficult to reach this requirement at present, is not that the preparation cost costliness is exactly that conversion ratio does not reach requirement.The reason of preparation cost costliness just is the use of precious metal palladium, platinum, rhodium.Up to now, precious metal is transition point in the use amount of catalyzer to contain 0.4% of total catalyst weight, and it is low that the catalyzer that consumption is lower than this transition point will show catalytic capability, the low problem of requirement that do not reach of conversion ratio; And, at present at precious metals such as palladium, platinum, rhodiums in Application of Catalyst, the usage ratio of rhodium is relatively large, the part by weight of palladium, platinum, rhodium is 6: 3: 1, rhodium metal is more expensive than palladium, platinum comparatively speaking, like this, cost is also just higher.Therefore, seek the more scientific and reasonable combination of a kind of carrier and noble coatings, it is following and guarantee the catalytic capability and the conversion ratio of catalytic body to make the consumption of precious metal reduce to transition point, is the direction of making great efforts in this technical field at present, and also being needs the bottleneck broken through.Though the preparation technology of catalytic body is being showing improvement or progress day by day at present, but the improvement to exhaust emission pollution requires also improving day by day, such as, many American-European countries just require in every kilometer particle number to be no more than the standard of 25mg/km to the emission of automobile wastes standard, and the automobile exhaust emission standard in Europe has developed into present European IV emission standard from originally I emission standard.In European IV emission standard, require motor vehicle exhaust emission to reach: the requirement of HC-0.46%, CO-1.5%, Nox-3.5%, PM-0.02%, and can reach this requirement at present and the use amount of precious metal is lower than the Bi Lu that 0.4% catalytic body yet there are no correlation technique.Therefore, the catalytic body that preparation cost is cheaper, technology is more advanced has great importance.

Summary of the invention

The purpose of this utility model provides a kind of catalytic body that is used for purifying internal combustion engine tail gas, and existing catalytic body precious metal use amount in administering the exhaust emission pollution process is excessive to overcome, cost is too expensive, the deficiency that conversion ratio is low.

For achieving the above object, the utility model has been taked such technological scheme: a kind of catalytic body that is used for purifying internal combustion engine tail gas, comprise carrier and coating, described carrier is that the porosity with pumiceous texture is first carrier of 20-60ppi, be coated with second carrier of one deck rare earth oxide at the skin of first carrier, the coating amount of second carrier is the 8-10% of first vehicle weight, skin at second carrier is coated with one deck noble coatings again, and the coating amount of noble coatings is every liter second a carrier 0.1-0.35 gram.

Described rare earth oxide is mainly formed by following feedstock production:

Zirconium oxide 25-35% cerium oxide 55-65% lanthana 3-7%

Yittrium oxide 3-7%

It is the coating that the ratio of 10-12: 2-3: 0.5-1 is prepared from the weight ratio that described noble coatings refers to by palladium, platinum, rhodium.

Take the utility model of above-mentioned measure, by carrier and the scientific and reasonable be combined into of coating, the use of saving aluminium sesquioxide has overcome the phenomenon of easy poisoning, meta particle diameter of the present utility model is 1.0-3.0 μ m, and fresh specific surface area is 30-50m when 1000 ℃ of 4hr ²/ g.The utility model matches to apply with foam-like first carrier and rare earth oxide and precious metal and forms, and can be applicable to the purification of industrial waste gas and vehicle exhaust.The utlity model has high-temperature stability, performance is stablized under 1100 ℃ temperature, does not decompose invariance, can store oxygen and discharge oxygen, promotes the dispersiveness of active component precious metal, improves catalytic activity and has anti-poisoning capability.When the utility model is applied to purifying vehicle exhaust, can significantly reduce the consumption of precious metal, the consumption of precious metal can be reduced to every liter of catalyzer 0.1-0.35 gram, and therefore, the waste-gas cleaning cost also significantly reduces.The utility model can reach more than 97% to the catalytic conversion efficient of waste gas, when the utility model is applied to purifying vehicle exhaust, can make automobile exhaust emission standard reach European IV emission standard, pollution index is controlled at HC-0.46%, CO-1.5%, Nox-3.5%, below the PM-0.02%.

Description of drawings

For describing the utility model in detail, described in detail below in conjunction with accompanying drawing.

Accompanying drawing 1 is the utility model stereogram;

Accompanying drawing 2 is the utility model cut-away views;

Mode of execution

With shown in the accompanying drawing 2, the utility model is made up of carrier and coating as accompanying drawing 1, and first carrier 1 is a kind of pumiceous texture, and shape has cylindrical, elliptical cylinder-shape is formed by calcining by materials such as steinheilite or metal or silicon carbide.Because the internal structure of first carrier 1 is irregular hole, void density reaches 20-60ppi, thereby has very big specific surface area.Be coated with second carrier, 2, the second carriers 2 that one deck is made up of rare earth oxide and be prepared from by zirconium oxide 25-35%, cerium oxide 55-65%, lanthana 3-7%, yittrium oxide 3-7% on the skin of first carrier 1, the preparation method is:

(1) getting above-mentioned zirconium oxide, cerium oxide, lanthana, yittrium oxide respectively pulverizes and is the fine powder of granularity less than 5 microns;

(2) above-mentioned each fine powder is dissolved in the salpeter solution respectively, and reaction generates cerous nitrate, lanthanum nitrate, zirconium nitrate and yttrium nitrate solution, wherein the concentration of cerous nitrate solution and zirconium nitrate solution is the 0.5-0.7 mole, and yttrium nitrate and lanthanum nitrate hexahydrate concentration are 0.5 mole;

(3) above-mentioned solution is mixed, in mixed solution, add and account for the surface active agent that volume is 6-8%, be cooled to and obtain the crystalline deposit thing under the room temperature condition and fold standby;

(4) get above-mentioned sludge centrifugal dehydration and separate, use to be higher than 90 ℃ pure water flush away impurity, and be washed till PH, remove the moisture in the sludge standby for neutral;

(5) with above-mentioned sludge in the temperature drying below 100 ℃, at temperature lower calcination 3-4 hour of 700-800 ℃, make sludge be converted into uniform oxide fully again;

(7) above-mentioned uniform oxide is pulverized be the fine powder below 3 microns and be prepared into pulpous state and get.

The coating amount of second carrier 2 that above-mentioned rare earth oxide is formed is 8-10% of first vehicle weight.Skin at second carrier 2 is coated with apposition one deck noble coatings 3, and noble coatings 3 is that the ratio of 10-12: 2-3: 0.5-1 is formed with the weight ratio by palladium, platinum, rhodium, and the coating amount of noble coatings 3 is every liter second carrier coating 0.1-0.35 grams.

Claims

1. catalytic body that is used for purifying internal combustion engine tail gas, comprise carrier and coating, it is characterized in that described catalytic body comprises that also the porosity with pumiceous texture is first carrier (1) of 20-60ppi, be coated with second carrier (2) of one deck rare earth oxide at the skin of first carrier (1), the coating amount of second carrier (2) is the 8-10% of first carrier (1) weight, skin at second carrier (2) is coated with one deck noble coatings (3) again, and the coating amount of noble coatings (3) is every liter second carrier (a 2) consumption 0.1-0.35 gram.