Mazda Motor Corporation

Takashi Takemoto

Akihide Takami

Masahiko Shigetsu

Hideharu Iwakuni

Makoto Kyogoku

Kazunari Komatsu

Yasuto Watanabe

Satoshi Ichikawa

Yuki Koda

Kazuo Misonoo

Hiroshi Yamada

Hiroshi Murakami

Toshitsugu Ueoka

Taeko Shimizu

Kenji Okamoto

Kenichi Yamamoto

Tadataka Nakazumi

Motoshi Kataoka

Hajime Suetsugu

Masayuki Koishi

Keiko Matsui

Kazuhiro Furukawa

Hideharu Iwakini

Tadashi Isobe

In the manufacturing process of the exhaust gas purifying catalyst (,), rhodium is supported by the base material using the rhodium carbonyl cluster solution in which rhodium carbonyl cluster is dissolved into methanol in the step of forming the upper catalytic layer (,) including rhodium and platinum as catalytic metals. By this, the dispersibility of rhodium in the base material is highly raised, and further rhodium is effectively restrained from being oxidized during the manufacturing process of the catalyst (,). Thus, according to the exhaust gas purifying catalyst (,) particularly, the purifying performance of NOx at both of lower exhaust gas temperature and higher exhaust gas temperature is highly improved.

Method of manufacturing catalyst

The active temperature of an exhaust gas cleaning catalyst is shifted to a higher temperature side when Al.sub.2 O.sub.3 and/or CeO.sub.2 is used as a co-catalyst and/or when an oxidation number of Pt or Ir which is used as the noble active component is plus four.

Exhaust gas cleaning catalyst component, process of production of the

In the exhaust gas purifying catalyst (3), palladium is contained as a catalytic component and cerium oxide and (Ce, Pr) compound oxide is contained as a promoter. Now, the weight ratio of cerium oxide to (Ce, Pr) compound oxide is set between 9/1 and 7/3, and the ratio of praseodymium to cerium in the (Ce, Pr) compound oxide is set between 3 mol % and 50 mol %. In this way, because in this exhaust gas purifying catalyst (3), palladium with high low-temperature activity is used for a catalytic component, the exhaust gas purifying performance at low temperature is improved. And because cerium oxide and (Ce, Pr) compound oxide improves catalytic activity of palladium at high temperature, the exhaust gas purifying performance at high temperature, in particular, NOx purifying performance, is improved.

Catalyst for cleaning exhaust gas

An exhaust gas purifying catalyst is produced by, after contacting a ceria powder with a palladium solution and burning the ceria powder to support the palladium on the ceria powder, forming a coating layer of the ceria powder on a catalyst support and impregnating the coating layer with a solution of cerium and burning it to provide palladium oxide particles fixed around ceria particles and a ceria coating so as to cover the palladium particles.

Exhaust gas purifying catalyst and process of producing the same

A process is provided for the production of a catalyst useful for removing nitrogen oxides out of exhaust gases from internal combustion engines operated under lean burn conditions. The catalyst is produced by supporting at least one catalytic metal, such as platinum, iridium, rhodium, other transition metals and alkaline earth metals, as the active component on a support, such as a zeolite, by either wash-coating a solution of the catalytic metal components onto the support; evaporating off solvent from a mixture of solvent, catalyst material and support, or rapidly drying droplets of support and catalyst material containing slurry with a hot gas. The supported catalyst is activated by heating to a temperature of 150 to 300.degree. C. for a period of time sufficient to desorb catalytic material components, such as water, chlorine and ammonia, out of the pores of the catalyst that adversely affect the activity and heat resistance of the catalyst.

Process for production of catalyst for exhaust gas cleaning

A catalyst (3) for purifying an automotive exhaust gas, in which inner and outer catalytic layers (5,6), each of which has a base material and a catalytic material held by the base material, are stratified on a honeycomb-type carrier (4). In the catalyst (3), the inner catalytic layer (5) contains a palladium component as the catalytic component. Further the inner catalytic layer (5) contains a nickel oxide component for preventing poisoning of the palladium component. On the other hand, though the outer catalytic layer (6) contains a rhodium component as the catalytic component, it does not contain a palladium component nor a nickel oxide component.

Catalyst for purifying exhaust gas

An engine exhaust gas purifying catalyst contains, as active substances, platinum and at least one of iridium, III-B metals and IV-B metals. In particular, the catalyst contains mainly platinum and iridium and, desirably, rhodium as an additive catalyst substance.

Exhaust gas purification system and catalyst therefor

An exhaust gas purifying system for an automobile engine is equipped with a metal zeolite catalytic converter for deoxidizing and purifying nitrogen oxides in exhaust gas. The system controls and compulsorily changes the air-fuel ratio of the fuel mixture injected into the automobile engine based on a target air-fuel ratio only when the temperature of the exhaust gas, before entering the catalyst, is greater than a specific temperature.

Exhaust gas purifying system

An exhaust gas purifying catalyst includes a metal-containing silicate and a noble metal active species carried by the metal-containing silicate. The metal-containing silicate has a solid acid characteristic wherein the amount of acid within a region where an acidity function Ho is equal to or smaller than -3.0 ranges from 0.04 to 0.55 mmol/gr. The noble metal active species burns an hydrocarbon component of exhaust gases to decompose an NOx component also contained in the exhaust gases. The catalyst may include a binder for carrying the noble metal active species on the metal-containing silicate. The binder has a solid acid characteristic wherein the amount of acid within a region where the acidity function Ho is equal to or smaller than -3.0 ranges from 0.04 to 0.55 mmol/gr.

Catalyst for exhaust gas purification

An exhaust gas purification system having a catalyst for removing nitrogen oxides from exhaust gas causes the temperature range of activation of the catalyst to shift toward the higher temperature side when the degree of oxidation of the catalyst becomes pronounced.

Engine exhaust gas purification system

An exhaust gas purifying catalyst includes an active compound, including platinum (Pt) and iridium (Ir), as an essential active compound base and any combination of two or more metals of terbium (Tb), nickel (Ni), indium (In), tin (Sn), cobalt (Co) and cerium (Ce), excepting a combination of indium (In) and tin (Sn), as an additive active material. The base and additive active material are deposited on and carried by a silicate carrier.

Exhaust gas purification catalyst

A catalytic convertor for treating exhaust gas includes a first catalyst layer formed on a base material and a second catalyst layer formed on the first catalyst layer. The first catalyst layer is composed of metal-containing silicate provided with transition metal by ion exchange and at least one precious metal borne on the silicate, and the second catalyst layer is composed of metal-containing silicate provided with transition metal by ion exchange and at least one metal borne on the silicate which is selected from the group consisting of Zr, Co, Cu, Cr, Mn, Y, Fe, Ni, V, Ti, Zn, Ga, Ba, Mg, La, Ce, Pr, Nd, Sm and Tb and differs from the transition metal provided on the silicate by ion exchange.

Catalytic converter for treating exhaust gas

A catalyst for cleaning an exhaust gas includes a metal containing silicate containing Al and a metal M constituting a crystalline structure which is selected from a group consisting of Ga, In, B, Mn, Bi, Sc Y, V and Ta, a transition metal or a precious metal being carried in said metal containing silicate. The catalytic active range can be expanded.

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Higashihiroshima, Japan

Takashi Takemoto