Nissan Motor Company Limited

Naoki Kachi

Masanori Nakamura

Kimiyoshi Nishizawa

Ritsuo Sato

Hiroyuki Kanesaka

Takamasa Nakagawa

Mikio Tsuzuki

Misaki Fujimoto

An exhaust gas purifying catalyst () of the present invention includes anchor/promoter simultaneous enclosure particles () including catalyst units () which contain: noble metal particles (); and anchor particles () as an anchor material of the noble metal particles () supporting the noble metal particles (); promoter units () which are provided not in contact with the noble metal particles () and contain first promoter particles () having an oxygen storage and release capacity; and an enclosure material () which encloses both the catalyst units () and the promoter units (), and separates the noble metal particles () and the anchor particles () in the catalyst units () from the first promoter particles () in the promoter units (). The exhaust gas purifying catalyst () further includes second promoter particles () which have the oxygen storage and release capacity, and are not enclosed in the anchor/promoter simultaneous enclosure particles () by the enclosure material ().

Exhaust gas purifying catalyst and method for manufacturing the same

A plurality of catalysts (,), (,) are disposed in an engine exhaust passage (,). At least the catalyst disposed downstream of these catalysts comprises a multi-layered catalyst (,) which is covered in a catalyst layer (,) on the surface and an HC absorbent layer (,) on an inner layer with respect to a catalyst carrier (,). A ratio of the downstream multi-layered catalyst (,) (catalyst heat capacity/catalyst surface area) is set so that it is greater than the same ratio for the upstream catalyst (,). In this way, temperature increase in the upstream catalyst (,) is advanced, the temperature gradient in the downstream catalyst (,) is increased and temperature rises in the HC absorbent layer are reduced. As a result, the HC emission period approximates the activation period of the catalyst layer (,). In this way, during low temperature vehicle operation, it is possible to synchronize the timing of HC emission by the HC absorbent layer and catalyst activation and therefore to achieve extreme reductions in HC emitted to the outside atmosphere.

Emission control device for internal combustion engine

A catalyst for the purification of exhaust gas comprises a first coating layer of activated alumina containing at least one of Pt, Pd and Rh, a second coating layer of activated alumina containing no noble metal and a third coating layer of zeolite ion-exchanged with Cu or Co and develops excellent purification performance in lean-burn atmosphere after engine aging treatment.

Catalysts for the purification of exhaust gas

Growing community of inventors

Kawasaki, Japan

Naoki Kachi