KR20070035816A - Catalytic converter for automobile exhaust gas and manufacturing method of coating catalyst - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic converter and a coating catalyst manufacturing method for automobile exhaust gas purification. More particularly, the present invention relates to CO in exhaust gases generated from diesel engines, lean-burn gas engines, lean-burn gasoline engines, and other fixed combustion sources. It is invented to effectively control and control (carbon monoxide) and HC (hydrocarbon) at the same time and to control the particulate matter (Particulate matters) more than the regulation value at the same time.

The configuration of the present invention is coated with a coating material containing platinum as a main component, and the wire mesh carriers 10 and 20 made of stainless steel;

The other carriers 10 and 20 in which the wire mesh carriers 10 and 20 are adjacent to each other are formed by arranging a plurality of different carriers having different densities.

Exhaust gas, catalyst, conversion, carrier, density

Description

A catalyst converter for purifying an exhaust gas of an automobile and the method of manufacturing a coating catalyst

1 is an enlarged perspective view showing the shape of a wire used for weaving a carrier of the present invention.

Figure 2 is a perspective view showing a state woven from steel wire.

3 is a perspective view showing a state in which a cylindrical woven mesh is compressed by a roller.

Figure 4 is an exemplary view showing a state in which the carrier of the present invention are installed successively at different densities.

5 is an understanding showing the state in which the exhaust gas is passed between the carriers of different densities and refracted and diffused.

Figure 6 is an understanding showing the state that the exhaust gas is passed between the carriers of different densities, refracted and diffused and vortex.

Figure 7 is an understanding of the chemical changes in the harmful exhaust gas passing through the catalytic converter of the present invention.

* Description of the symbols for the main parts of the drawings *

1-wire 2,3-roller

10,11-wire mesh carrier

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic converter and a coating catalyst manufacturing method for automobile exhaust gas purification. More particularly, the present invention relates to CO in exhaust gases generated from diesel engines, lean-burn gas engines, lean-burn gasoline engines, and other fixed combustion sources. It is invented to effectively control and control (carbon monoxide) and HC (hydrocarbon) at the same time and to control the particulate matter (Particulate matters) more than the regulation value at the same time.

In general, most automobiles, especially diesel vehicles using diesel fuel, have operated without a catalytic converter until recently, but in the 2000s, DOC converters (Diesel Oxidation Catalyst Converters) according to environmental regulations were to be installed.

This DOC is attached to the exhaust side of the engine exhaust manifold to catalyze precious metals, such as platinum (Pt) or platinum (Pt) + rhodium (Rh) or platinum (Pt) + rhodium (Rh) + palladium (Pd). It is used to reduce CO and HC in exhaust gas simultaneously.

This DOC converter's purifying action occurs when the engine is operated near the theoretical air-fuel ratio, and the reaction takes place according to the catalytic reaction. The normal reaction temperature is about 300 to 500 ° C, and it is responsible for oxidizing HC and CO.

Conventionally, the carrier of the catalyst is a situation that uses a honeycomb (Ceramic honeycomb type).

The ceramic honeycomb moving source catalyst is vulnerable to temperature change because the honeycomb carrier is made of ceramic material.

In addition, it does not play a role as a catalyst during the time required to reach the optimum reaction temperature in the early stage of operation, and also has a lot of problems in durability due to its weak physical properties. have.

SUMMARY OF THE INVENTION An object of the present invention is to provide a catalytic converter for automobile exhaust gas purification which has a high exhaust gas reduction rate due to more smooth oxidation.

Another object of the present invention is to provide a catalytic converter for automobile exhaust gas purification, in which the coated catalyst lowers the ignition temperature of particulate matter and the like to promote self-burning of exhaust gas, high CO and HC reduction efficiency, and greatly reduce particulate matter when using ultra low sulfur. It is.

The catalytic converter of the present invention is a stainless steel (Stainless Steel) material, a wire mesh made of a cylindrical shape by pressing the press into a mold according to the shape required, various column shapes, such as circular column, triangular column, square column and elliptical column It is designed to fit the structure of the moving source by molding.

The wire made of stainless steel is rolled into the first thin circular wire shape and deformed into a thin wire 1 shape with a size of 0.15-0.25 thickness and 0.4-0.6 width as shown in FIG. It will relatively increase the specific surface area of the catalyst carrier.

Therefore, the effect of increasing the catalyst role and at the same time, the turbulence of the exhaust gas flows inside the carrier according to the lamination method due to the wire mesh type carrier structure.

In addition, Brownian motion, which is an irregular motion of the particles in the fluid, is generated, that is, a phenomenon in which small particles are irregularly moved due to the heat of the exhaust gas (thermal motion of the molecules) appears.

In addition, the above phenomena are combined in the catalyst carrier such as the insertion, interception, thermal destruction, etc. between the small fine particles, and the reduction reaction of the fine particles is performed while increasing the efficacy of the catalyst. This happens.

FIG. 2 shows a structure woven from a flat wire by rolling, and a process of making a cylindrical woven like a cloth and pressing it between the upper and lower rollers 2 and 3 as shown in FIG. It is shown.

In this manner, the wire mesh superimposed in two layers is rolled into a cylindrical shape or put into a mold by a press to form a circular, triangular, square, or elliptical columnar shape.

In this way, it is important to arrange the carriers 10 and 20, which are compacted by the press, in a plurality of layers between 3 and 8 so as to have a large surface area.

At this time, by varying the density (weight per unit area, g / cm 3) for each layer of the carriers 10 and 20, turbulence, brownian motion, molecular interference, and interception It will be designed to further induce the phenomenon of.

4 shows an example in which the unit wire mesh carriers 10 and 20 are arranged in four layers.

The density of the wire mesh carriers 10 and 20 used in the present invention is designed to selectively use a density of 0.20 g / cm 3 to 0.80 g / cm 3 for each mesh EA.

In addition, the number of stacked layers of the wire mesh carriers 10 and 20 can be overlapped with up to eight layers, and the density of the entire wire meshes 10 is also designed not to exceed 0.80 g / cm 3.

The wire mesh carriers 10 and 20 in a plurality of layers are filled in a tube-shaped case, and then inserted into the tube case by spot welding or the like, and then a metal honeycomb type auxiliary carrier is used to exhaust the catalyst gas. It may be selectively attached and treated at the inlet and outlet.

This auxiliary carrier helps to maximize the characteristics of the catalyst reaction by varying the flow of exhaust gases to be treated.

Meanwhile, when the wire mesh carriers 10 and 20 are arranged in four layers as shown in FIG. 4, it is effective to arrange the density of each wire mesh carrier 10 and 20 differently. It is effective to design the carrier by adjusting the density size order of (20) to 1 <2 <3 <4 or 1 <4 <2 <3 and the like.

That is, due to the difference in density at the boundary between the wire mesh carriers 10 and 20 arranged successively, the larger vortices, brown motion, molecular insertion, blocking, and the like can be exhibited.

In addition, the auxiliary carrier is designed so as to maximize catalyst characteristics by inserting the auxiliary carrier into the exhaust gas inlet or outlet, or inlet, outlet, or wire mesh carriers 10 and 20 between various stages. You can do it.

When the wire mesh carriers 10 and 20 are arranged at different densities, the shape of the exhaust gas can be predicted as shown in FIGS. 5 and 6, and the Brownian motion varies greatly depending on the structure of the stack. The effects of motion, insertion and turbulence can be diversified to maximize the effect of thermal reduction.

According to the wire mesh carrier structure thus constructed, a commercially available porous high surface area such as γ-Al ₂ O ₃ or δ-Al ₂ O _3, and sulfur component contained in alumina It was confirmed that the inhibition of the formation of nitrogen oxides and the oxidation of hydrocarbon (HC) and carbon monoxide (CO) help to increase the removal efficiency of HC and CO.

In particular, the exhaust gas emitted from diesel vehicles consists of particulate matter (PM), hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx). It can be subdivided into fractions, sulfates, and soot.

It is difficult to remove harmful exhaust gas components because of high oxygen concentration and low temperature. Have

On the other hand, the wire mesh carrier 10, 20 of the present invention is Pt (platinum) or Pd (paldium) Rh (rhodium) or Ti on highly purified alumina (γ or δ type) (with 0.05 wt% S), A catalyst component composed of various additives such as W, Mo, and V is coated.

The combined components of the coated catalysts oxidize SOF (Soluble Organic Fraction) in HC, CO and particulate matter (PM), showing high reduction efficiency.

According to the test results, the main catalyst component of single Pt (Platinum), Pt (Platinum) and Pd (Palladium) in combustion of Sulfate (SOx) component in exhaust gas is less than 1000ppm, 500ppm and ultra low sulfur or less than 5ppm Even under the conditions, the reduction of NOx production and the oxidation reaction of HC, CO and SOF react smoothly, showing high reduction efficiency.

Then, after differentiating the density of the wire mesh carriers 10 and 20, the vortex according to the lamination method, the carrier density adjustment, and the arrangement design of the auxiliary carriers arranged before and after the wire mesh carriers 10 and 20. , The effect of the reaction inside the carrier (10, 20) due to the insertion, blocking, and Brownian motion phenomenon is increased, the thermal destruction of the microparticles shows higher removal efficiency than the ceramic honeycomb that is a single structure have.

Thus, according to the catalytic converter of the present invention, the thermal shock tolerant was maintained even at a very high temperature of about 2000 ° C.

In addition, the impact received on each axis of the catalyst carriers 10 and 20 also maintains very high strength in all the axial directions, and thus maintains superior performance in comparison with existing catalysts even in durability.

In addition, since the wire mesh carriers 10 and 20 are made of stainless steel, the thermal conductivity is high and the catalytic reaction temperature is reached even in a short time to start the catalytic reaction.

This indicates that the light off temperature is very low, and that the sustainability of light off temperature performance is also high.

On the other hand, the catalyst coated on the wire mesh carriers 10 and 20 is a maximum of 1000 ppm in a coating catalyst in which a single platinum (Pt) and palladium (Pd) are mixed at a 5: 1 ratio on highly purified alumina (γ or δ type). It was confirmed that the oxidation reaction occurred well under the sulfur component of, and the back pressure was also very low, and it was also confirmed that it could be adapted to various back pressures as needed.

The manufacturing method of such a coating sheet is as follows.

Pt component and Pd component combined with purified γ-Al ₂ O ₃ or δ-Al ₂ O ₃ and alumina monohydrate and Ti, W, Mo, V, Ce, etc. Is made.

In other words, the wire mesh carriers 10 and 20 are loaded with a ratio of Pt and Pd of 5: 1. Pt and Pd are mixed with purified Al ₂ O ₃ and alumina monohydrate or a combination oxide of these materials. After dissolving in solution, it is dried by drying at 100-120 ° C. and calcined step by step under a programmable temperature of 100-650 ° C. under an oxygen or air atmosphere.

At this time, the boehmite is converted to Al ₂ O ₃ in the sintering step to have a large specific surface area.

In addition, the coating solution different from the above can also be dissolved in Pt (Pt and Pt compounds) and an aqueous solution containing Ti, W, Mo, V and Ce and components.

That is, in the aqueous solution in which purified Al ₂ O ₃ , boehmite or a combination oxide of these substances is dissolved, W, Mo. After dissolving ammonium salt containing V and Ce components (Ammonium Soft) and dissolving dinitrate and zeolite powder solution, go through drying and firing steps under the above conditions, or sequentially dissolving in solution containing each substance and drying and It goes through the firing step.

Pt and Pd, which are the main catalysts, are supported on Al ₂ O ₃ and spread evenly on the surface of the stainless steel wire mesh carriers 10 and 20 during the sintering step. If the thickness of ~ 60mm, the oxidation of Hc, CO, SOF is smooth, showing high reduction efficiency and increasing the reduction rate of fine particles.

That is, the catalyst coated on the wire mesh carriers 10 and 20 lowers the ignition temperature of the fine particles (PM) to promote self-burning of the exhaust gas, high CO and HC reduction efficiency, and 25% particulate matter when using ultra low sulfur. This is to reduce the abnormality.

The reaction scheme reacted at this time is as follows.

<Table 1> shows the data of CO, HC, and PM (including SOF) values measured by various vehicles using diesel fuel.

As shown in this table, the measured value with very high average reduction rate was obtained.

The catalyst according to the present invention includes HC (hydrocarbon), carbon monoxide (CO) and fine particles (PM) in exhaust gas generated from a mobile combustion source such as a diesel engine Lean-Burn (Lean-Burn) gas engine, or a Lean-Ban gasoline engine. You can effectively control.

Therefore, it is a very useful invention for removing nitrogen oxides generated from various types of diesel engines and combustion apparatuses.

Claims (4)

Wire mesh carriers 10 and 20 coated with a platinum-based coating material and made of stainless steel; A catalytic converter for automobile exhaust gas purification, characterized in that a plurality of different carriers (10) (20) in which the wire mesh carriers (10) (20) are adjacent to each other are arranged in plural ones having different densities. The method according to claim 1, wherein the coating material is on the purified alumina (γ or δ type) for purification of automobile exhaust gas, characterized in that consisting of a coating catalyst mixed with a single platinum (Pt) and palladium (Pd) in a 5: 1 ratio. Catalytic converter. The method of claim 1, wherein the coating material is a coating containing Pt (Pt and Pt compounds) and Ti, W, Mo, V and Ce components in an aqueous solution in which purified Al ₂ O ₃ , boehmite or combination oxides of these materials are dissolved. Catalytic converter for automobile exhaust gas purification, characterized in that made of a catalyst. Purified Al ₂ O ₃ and alumina monohydrate or combination oxides of these materials were dissolved in a mixed solution of Pt and Pd 5: 1, dried at 100 to 120 ℃ and calcined at 100 to 650 ℃ under an air atmosphere. Coating catalyst manufacturing method, characterized in that.

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