JPS61149246A - Method for supporting catalyst - Google Patents

Abstract

PURPOSE:To enhance the durability of purification capacity as a catalyst, by supporting a fine particle of a catalytic metal, which was preliminarily dispersed uniformly in a solvent, by the surface of particulate activated alumina by utilizing ultrasonic vibration. CONSTITUTION:When an activated alumina particle as a catalyst carrier and a fine particle of a metal mixture of Cu and Ni is used as a catalytic metal, the fine particle of the catalytic metal is at first preliminarily dispersed in a solvent such as water or alcohol by utilizing ultrasonic vibration. Subsequently, this dispersion is mixed with a slurry having the activated alumina particle suspended therein to coat the surface of the activated alumina particle with the fine particulate catalytic metal and the coated particle is dried and baked. By this supporting method, because the growth of a particle due to the mutual flocculation of fine particles of the catalytic metal applied to the surface of the activated alumina particle is not generated, the catalyst excellent in durability of purification capacity is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of supporting a catalyst, and more particularly, in the production of a catalyst for purifying exhaust gas of an internal combustion engine, ultrasonic vibration is used to support a catalyst uniformly in a solvent. The present invention provides a method for supporting a catalyst that has excellent durability in purification performance as a catalyst by supporting fine particles of a dispersed catalyst metal on the surface of activated alumina particles.

[Conventional technology]

Exhaust gas purification catalysts used in internal combustion engines for automobiles use activated alumina particles as a carrier that holds fine particles of catalytic metal and improves catalytic activity.Cu, Ni, and Fe are added to the particle surface. , Mn, Co
Catalysts supported on fine particles of catalytic metals such as , Pd, and Pt are commonly used.

Conventionally, in the production of exhaust gas purification catalysts used in automobile internal combustion engines, etc., Cu, Ni, Fe, etc. .

By mixing fine particles of catalytic metals such as Mn, Co, Pd, and Pt as they are, the surface of activated alumina particles is coated with fine particles of catalytic metals, and then dried and fired to form a catalyst for exhaust gas purification. It was normal to do so.

[Problem that the invention seeks to solve]

In view of the current state of the conventional technology as described above, the problem that the present invention attempts to solve is that in the conventional catalyst supporting method as described above, the catalyst metal coated on the surface of activated alumina particles that are the catalyst carrier is This means that the fine particles of the catalyst agglomerate together, causing particle growth of the catalytic metal, which impedes the durability of the purification performance of the manufactured catalyst.

Therefore, the technical problem of the present invention is to create a dispersion liquid in which fine catalyst metal particles are uniformly dispersed in a solvent using ultrasonic vibration in the production of a catalyst for purifying exhaust gas of an internal combustion engine. By mixing activated alumina particles in a suspended slurry, the fine particles of the catalyst metal coated on the surface of the activated alumina particles coagulate with each other and coat the surface of the activated alumina particles without causing particle growth of the catalyst metal. The object is to support the catalyst and to improve the durability of the purification performance as a catalyst.

[Means for solving problems]

In view of the problems in the conventional technology, the present invention provides a method for supporting a catalyst in which fine particles of a catalyst metal are supported on the surface of activated alumina particles. First, a dispersion liquid is prepared by uniformly dispersing fine particles of catalytic metal in a solvent such as water or alcohol using ultrasonic vibration, and then this dispersion liquid is mixed into a slurry in which the activated alumina particles are suspended. After coating the surface of activated alumina particles with catalyst metal in the form of fine particles,
It consists of a catalyst supporting method characterized by drying and calcining.

[Effect]

Hereinafter, the effects of the present invention will be explained.

The reason why the catalyst supporting method of the present invention has the above-described structure is that fine catalyst metal particles uniformly dispersed by ultrasonic vibration are grown on the surface of activated alumina particles, which are catalyst carriers. By coating the dried and calcined catalyst without causing any damage, fine particles of catalyst metal are uniformly dispersed and supported on the surface of activated alumina particles, which is the carrier, and the durability of the purification performance as a catalyst is improved. This is for the purpose of

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

In this example, an example will be described in which activated alumina particles are used as the catalyst carrier and fine particles of a mixed metal of CU and Ni are used as the catalyst metal.

In the catalyst supporting method according to the present invention, first, fine particles of catalyst metal are uniformly dispersed in a solvent such as water or alcohol using ultrasonic vibration.

Next, 00g of alumina silua with an alumina content of 10% by weight, and 150g of an 8w1 aluminum aqueous solution with an alumina content of 40% by weight.
Then, 450 ml of distilled water was added and stirred to prepare a mixed suspension.

Then, 900% of alumina particles were added to the above mixed suspension.
10 g, fine particles (20-30μ) of catalyst metal mixed with pre-dispersed Cu and Ni at a ratio of 171
A dispersion liquid containing 0 g was added and stirred to prepare a slurry in which fine particles of activated alumina and catalyst metal were suspended.

A cylindrical monolith carrier base material with a diameter of IQ cm and a length of 15 cm was immersed in this slurry in which fine particles of activated alumina and catalyst metal were suspended for 1 minute, and then air was blown onto the cylindrical monolith carrier base material. After blowing off the slurry in the cell, a drying process was performed at 200"CX for 1 hour, and then a baking process was performed at 700° C. for 2 hours in an inert gas atmosphere.

The cylindrical monolith carrier base material supporting the catalytic metal in this way is again immersed in the slurry in which the above-mentioned activated alumina and fine particles of the catalytic metal are suspended, and the same operation is repeated to catalyze the catalytic metal. A was produced.

Next, for a catalyst manufactured by a conventional catalyst supporting method as a comparison, 00 g of alumina silica with an alumina content of 10% by weight and 150 g of an aluminum nitrate aqueous solution of 40% by weight were added, and then 450 ml of distilled water was added.
was added and stirred to prepare a mixed suspension.

To the mixed suspension, 900 g of activated alumina particles and 100 g of the same catalyst metal fine particles as used in the method of the present invention, which had not been previously dispersed, were added, and the activated alumina and catalyst metal fine particles were added. A slurry with suspended particles was prepared.

A cylindrical monolith carrier base material with a diameter of 10 cm and a length of 15 cm is immersed in this slurry in which fine particles of activated alumina and catalytic metal are suspended for 1 minute, and the same operation as in the method of the present invention described above is repeated. A catalyst was prepared by this method.

Thereafter, the two types of catalysts a and b were subjected to a durability test using the following method, and their purification performance was then evaluated.

The durability test conditions were: engine air fuel ratio (A/F); 14.
6. Space velocity (sV): 60000h, catalyst bed temperature: 7
After operating at 20°C for 300 hours, the purification rate of each catalyst was measured.

The purification rate was measured using a method of evaluating the temperature characteristics of the purification rate of the catalyst using an air-fuel ratio (A/F) of 14°6.The measurement results are shown in the figure.

Note that the purification rate in this figure is based on Co
, HC, and NOx showed similar trends.

As is clear from the figure, catalyst a produced by the catalyst supporting method of the present invention has better low-temperature purification performance even after a 300-hour long-term durability test compared to catalyst A produced by the conventional catalyst supporting method. This shows that the catalyst produced by the catalyst supporting method of the present invention has excellent durability in terms of purification performance.

〔Effect of the invention〕

As is clear from the above, according to the catalyst supporting method of the present invention, fine particles of catalyst metal are uniformly dispersed in advance in a solvent using ultrasonic vibration in the production of a catalyst for purifying exhaust gas of an internal combustion engine. By mixing the resulting dispersion into a slurry in which activated alumina particles are suspended, the fine particles of the catalyst metal coated on the surface of the activated alumina particles coagulate with each other and are activated without causing particle growth of the catalyst metal. It has the advantage that it can be supported on the surface of alumina particles to improve the durability of its purification performance as a catalyst.

[Brief explanation of drawings]

The figure shows the evaluation results of catalyst activity. a-----1 Catalyst produced by the method of the present invention. b --------1 Catalyst produced by a conventional method. Applicant: Toyota Motor Corporation Å uniform streaks (°0)

Claims (1)

[Claims] 1. A method for supporting a catalyst in which fine particles of a catalyst metal are supported on the surface of activated alumina particles, the fine particles of a catalyst metal being uniformly dispersed in a solvent such as water or alcohol by ultrasonic vibration. A dispersion liquid is prepared, and then this dispersion liquid is mixed into a slurry in which the activated alumina particles are suspended, so that the surface of the activated alumina particles is coated with the catalyst metal in the form of fine particles. ,
A catalyst supporting method characterized by drying and firing.