JPS62140643A - Production of porous catalyst for purifying exhaust gas - Google Patents

Abstract

PURPOSE:To reduce the deactivation of the titled catalyst due to poisoning and to enhance the catalytic activity by coating and depositing a metallic catalyst over the whole surface of a highly porous carrier consisting essentially of calcium aluminate powder, and heat-treating the material to mold an exhaust gas purifying catalyst. CONSTITUTION:A pasty mixture consisting essentially of calcium aluminate powder and added with aggregate, a molding assistant, and water is prepared. The mixture is then molded, cured, and dried to form a highly porous carrier. A metallic catalyst component is deposited on the highly porous carrier, and the whole surface of the carrier is coated with metal to obtain the porous catalyst for purifying exhaust gas. Nickel, copper, chromium, cobalt, etc., are used as the catalytic metal to be coated, and molten silica, titanium dioxide, etc., are used as the aggregate. In the heat treatment at about 1,000 deg.C, the specific surface is not changed and remains at a high value of 15-20m<2>/g, and the catalytic activity is not deteriorated under high temp. conditions.

Description

[Detailed description of the invention] Industrial application field The present invention is applicable to exhaust gases emitted from automobiles, factories, etc.
The present invention relates to a method for producing a porous catalyst that purifies combustion exhaust gas such as oil and gas, and incomplete combustion gas such as oil smoke during cooking.

Conventional technology Conventionally, this type of porous catalyst for purification of sulfur gas was disclosed in Japanese Patent Application Laid-open No. 1986-
As described in Japanese Patent No. 161327, lime aluminate, fused silica, titanium dioxide, molding aids, etc. are mixed, water is added and kneaded, the mixture is molded into a honeycomb shape, and then hardened and dried. The obtained honeycomb carrier was immersed in a salt solution of platinum group metal or the like to support a metal catalyst, and then heat-treated.

Problems to be Solved by the Invention The honeycomb carrier obtained by such a conventional method has a
When heat treated at a temperature of about 00℃, the specific surface area decreases,
There were problems with durability, such as a decrease in catalyst activity.

An object of the present invention is to solve the above-mentioned conventional problems by supporting a metal catalyst on a press, subjecting it to a metal catalyst, and then heat-treating the catalyst.

In order to achieve this objective, the present invention uses lime aluminate as the main component and fused silica as the aggregate.

Titanium dioxide and powder materials such as molding aids are mixed, water is added and kneaded, molded into a highly porous shape, hardened and dried to obtain a highly porous carrier ()/nicum carrier) with platinum as a catalyst, After impregnating with an aqueous solution of metal salts such as palladium and cerium,
It is coated with metal such as nickel, chromium, copper, or cobalt, and then heat treated.

Function: This manufacturing method prevents the honeycomb catalyst from deteriorating due to poisoning, and even after heat treatment at temperatures as high as 1000°C, the specific surface area remains as large as 16 to 20 m and 7 g, and the catalytic activity at high temperatures remains unchanged. It is possible to obtain improved durability such as no deterioration.

Example Embodiments of the present invention will be described below with reference to the drawings.

[Example 1] The composition of the carrier was 40 parts by weight of lime aluminate, 45 parts by weight of fused silica, and 15 parts by weight of titanium dioxide, and 3 parts by weight of carboxymethylcellulose was added as a molding aid, and water was added to the powder. The resulting material was extruded using a honeycomb die, rapidly hardened and dried to obtain a honeycomb body. The honeycomb body was immersed in a mixed solution of platinum and palladium for about 10 seconds, so that 0.59 grams of platinum and 1 g of palladium could be attached to the surface of the carrier as a catalyst. After supporting, Ni was applied for 1Q minutes using a normal Watt bath at a current density of 0.5 to 1A/7.
It was plated to a thickness of 6 μm. Then, in an inert gas of N2,
Heat treatment was performed at oo°C for 30 minutes.

[Example 2] A honeycomb carrier obtained in the same manner as in Example 1 on which a catalyst was supported was heated in an acid bath for 1 to 1. Cu was plated to a thickness of 1 to 5 μm for 10 minutes at tsA/, d, and then heat treated at 1000° C. in the same manner as in Example 1.

[Example 3] A honeycomb body obtained in the same manner as in Example 1 on which a catalyst was supported was heated to about 1°A/ffl in a chromic acid-sulfuric acid bath.
Plating was carried out to a thickness of 1 to S μm for 6 minutes at
Heat treatment was performed at 000°C.

[Example 4] A catalyst was supported on a honeycomb carrier obtained in the same manner as in Example 1, and the Ni in the Watt bath was replaced with C.

C for 10 minutes at 0.6-1A/6- in the solution replaced with
O was plated to a thickness of 1 to 6 μm, and then heat treated at 1000 C in the same manner as in Example 1.

[Example 6] In the same manner as in Example 1, Fe and Zn were used instead of the old ones.

plated.

[Comparative example]

A honeycomb carrier obtained in the same manner as in Example 1 was immersed in a mixed solution of platinum and palladium as a catalyst for about 10 seconds to support 0.51 g of platinum and 1 g of palladium per unit volume (1) of the carrier. 1000°C as in Example 1
It was heat treated.

Note that the supported catalyst may also be a lanthanum-based catalyst or the like.

The above six types of catalysts were prepared, heat treated at 1000C in an electric furnace, and the specific surface area was measured by the BET method. Figure 1 shows the result.

Furthermore, the results of measuring the carbon monoxide purification ability at 300°C and nitrogen dioxide purification ability at 700°C of six types of catalysts are shown in Figures 2 and 3, and the conditions for measuring each purification ability are shown in Table 1. .

Table 1 In the figures, 1 indicates Example 1, 2 indicates Example 2, 3 indicates Example 3, 4 indicates implementation, 4, 6 indicates Example 6, and 6 indicates comparative example, respectively.

As shown in No. 11A, in Comparative Example 6, the specific surface area decreases by U as the heat treatment is performed at high temperature for a long time. This seems to be caused by the disappearance of pores between the fine particles of the honeycomb catalyst. On the other hand, in Examples 1 to 4, the surface of the honeycomb catalyst was formed by metal plating to form a coating layer, and even when heat-treated, this metal coating layer prevented sintering of the honeycomb catalyst. I don't think so. Even if the Fe and Zn of Example 6 were plated, sintering could not be prevented.

Moreover, as shown in FIGS. 2 and 3 regarding each purification ability, Comparative Example 6 has lower performance than Examples 1 to 4. This is thought to be due to the deactivation of the foil-like gold pigeon due to sintering as well as the decrease in the specific surface concave edges mentioned above. Also, in Examples 1 to 4, the surface was covered with metal, so the catalyst This is thought to be due to the fact that the substance does not deteriorate due to poisoning.

Effects of the Invention As described above, the present invention has a catalyst that is supported in the manufacturing process and then coated with metal on the surface, so that even when heat treated at high temperatures for a long time, the specific surface area decreases little and there is little deactivation due to poisoning. The present invention provides a porous catalyst for exhaust gas purification that has good catalytic activity and a long life.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the relationship between heat treatment time and specific surface area determined by BET in Examples and Comparative Examples of the present invention;
The figure is a characteristic diagram showing the carbon monoxide purification ability of the heat-treated products in the same example and comparative example, and FIG. 3 is a characteristic diagram showing the nitrogen dioxide purification ability. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 100 2θθ Joo θ0
(H) Heat treatment left (/θ00'C) Fig. 2 1θo zm, 3θ (7400 (H) Fig. 3 Heat treatment lI! (/θOθ゛/θ0
2θOJθo, iθθ (H) Heat! FIR (/
θoo゛C) Procedural amendment December 26, 1985 T5' jF n''m u F2 (゛Σ1 case indication 1985 Patent Commissioner No. 283436 2 Name of invention Process for manufacturing porous catalyst for exhaust gas purification 3 Amendment Relationship with rFl Patent issued
Address: 1006 Oaza Kadoma, Kadoma City, Osaka Name (582) Representative of Matsushita Electric Industrial Co., Ltd.
Akio Tanii 4 Agent 571 Address 8, Matsushita Electric Industrial Co., Ltd., 1006 Oaza Kadoma, Kadoma City, Osaka Contents of amendment (1) "Catalyst" on page 3, line 4 of Specification A was changed to "catalyst" ” will be corrected. (2) Correct "catalyst" in line 10 of page 3 to "catalyst". (3) “CO” in Table 1 on page 6, line 14
Correct to o j. (4) “NO□” in Table 1 on page 6, line 19
Correct it to l'-NO□.

Claims (2)

[Claims] (1) A method for producing an exhaust gas purifying catalyst having a structure in which a catalyst is supported on a porous carrier, in which the main component is lime aluminate powder, and water is added to a mixture of this, aggregate, and a molding aid. A method for producing a porous catalyst for exhaust gas purification, in which a metal catalyst is supported on a highly porous carrier obtained by making it into a paste form, followed by molding, curing, and drying, the entire surface of which is coated with metal, and then heat treated. (2) The method for producing a porous catalyst for exhaust gas purification according to claim 1, wherein the metal to be coated is any one of nickel, copper, chromium, and cobalt.