JP3336345B2 - Palladium-lanthanum composite oxide catalyst and supported catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a palladium oxide catalyst used for a combustion catalyst or the like.

[0002]

2. Description of the Related Art Conventional oxidation catalysts include:
A high surface area carrier such as alumina is used for cordierite honeycomb.
0-100 g / l washcoat, impregnation method,
What carried out 5-20 wt% of palladium with respect to the support | carrier alumina using the ion exchange method etc. was mainly used as a catalyst. However, it is already known that the supported palladium exhibits the activity as an oxidation catalyst only after it becomes palladium oxide. Since the catalyst loses its activity, it cannot be used as an oxidation catalyst at 800 ° C. or higher.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the drawbacks of the conventional palladium oxide catalysts.
An object of the present invention is to provide an oxidation catalyst that can be used as the above oxidation catalyst.

[0004]

The present invention relates to a palladium-lanthanum-based composite oxide catalyst in which the ratio of palladium oxide to lanthanum oxide is 1: 2 to 2: 1 by mole, wherein alumina or Alumina containing one or more rare earth metals and alkaline earth metals, or zirconia or zirconia containing one or more rare earth metals and alkaline earth metals, is wash-coated, and the palladium-lanthanum-based This is a supported catalyst supporting a composite oxide catalyst.

The reason that the molar ratio of palladium oxide to lanthanum oxide is 1: 2 to 2: 1 is that the activity of palladium oxide as an oxidation catalyst is not reduced and the palladium oxide can withstand a combustion temperature of methane or the like as a combustion catalyst. This is because the catalyst can be used. The palladium-lanthanum-based composite oxide catalyst in this ratio can withstand temperatures of 1100 to 1200 ° C. and maintain its activity.

Further, a carrier supporting the palladium-lanthanum composite oxide catalyst contains alumina or alumina containing at least one rare earth metal and an alkaline earth metal, or zirconia or zirconia contains one or more rare earth metals. And those containing an alkaline earth metal are wash-coated in the above-described range from 1100 to 120
It is a carrier that can withstand a temperature of 0 ° C., and can provide a high surface area for effectively utilizing the catalyst, and can be firmly supported when a palladium-lanthanum-based composite oxide catalyst is supported. is there.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the Examples do not limit the present invention.

[0008]

EXAMPLE 1 1.3 g of lanthanum acetate and 2.6 g of palladium chloride were dissolved in distilled water, and a length of
A carrier coated with a 100 g / l alumina washcoat of alumina is immersed in a cordierite honeycomb carrier having a diameter of 5 mm × 20 mm. Next, the carrier was taken out, dried at 100 ° C. for 30 minutes, and then calcined at 750 ° C. for 3 hours to carry a palladium-lanthanum composite oxide catalyst supporting 0.16 g as palladium and 0.05 g as lanthanum. A supported catalyst was obtained. The test as an oxidation catalyst was carried out by combustion of methane. The complete combustion F / A ratio of methane could be maintained for 10 hours or more, and the combustion temperature was measured to be 1050 ° C. Separately, when the effective temperature of the catalytic activity of the supported catalyst was confirmed by a combustion test,
It showed activity as an oxidation catalyst up to 05 ° C.

[0009]

Example 2 5.2 g of lanthanum acetate and 2.6 g of palladium chloride were dissolved in 50 ml of distilled water, and a carrier coated with a cordierite honeycomb carrier having a length of 25 mm × 20 mm in advance and a wash coat of alumina at 100 g / l was used. Soak. Next, the carrier was taken out, dried at 100 ° C. for 30 minutes, and then calcined at 750 ° C. for 3 hours to obtain 0.16 g of palladium and 0.1 g of lanthanum.
A supported catalyst supporting a palladium-lanthanum-based composite oxide catalyst supporting 21 g was obtained. The test as an oxidation catalyst was carried out by combustion of methane.
It could be continued for more than an hour, and the combustion temperature was measured to be 1150 ° C. Separately, the effective temperature of the catalyst activity of the supported catalyst was confirmed by a combustion test.
It showed activity as an oxidation catalyst up to 190 ° C.

[0010]

Conventional Example A palladium oxide-supported catalyst was prepared in the same manner as in Example 1 except that lanthanum acetate was not added and the amount of palladium chloride was changed to 2.6 g. The complete combustion of methane was stopped in less than one hour, and the temperature was lowered and the fuel was burned again.

[0011]

As is apparent from the above description, according to the palladium-lanthanum-based composite oxide catalyst and the supported catalyst of the present invention, 800 palladium oxide, which was conventionally effective only as an effective oxidation catalyst, could not be used. The activity hardly decreases even at a temperature of at least
It can withstand a high temperature of about 200 ° C., and can be used as a combustion catalyst particularly for methane and the like.

Continuation of the front page (56) References JP-A-63-88041 (JP, A) JP-A-4-27433 (JP, A) JP-A-62-121642 (JP, A) JP-A-62-149343 (JP) JP-A-63-296842 (JP, A) JP-A-61-209045 (JP, A) JP-A-62-282642 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB Name) B01J 21/00-38/74

Claims (2)

(57) [Claims] 1. An atomic ratio of palladium to lanthanum of 1: 1.
To 1: Palladium is a 4 - or lanthanum-containing composite oxide
Combustion catalyst, characterized in that Ranaru. 2. A method in which alumina or alumina is added to the carrier in advance.
A washcoat is applied with one or more rare earth metals and alkaline earth metals, or zirconia or zirconia containing one or more rare earth metals and alkaline earth metals, wherein the atomic ratio of palladium to lanthanum is 1: A combustion catalyst comprising a palladium-lanthanum-containing composite oxide of 1 to 1: 4 supported thereon.