US 5,334,570 A · Pore impregnated catalyst device

Abstract

A porous catalyst support which may be used in a catalytic converter for treating automotive exhaust gases. The support comprises a substrate having a multichannel structure of generally thin walls and washcoat particles of colloidal particle size mainly or wholly within the pores of the walls so as to increase open frontal area and reduce back pressure. Substrate is either ceramic or metal. In a ceramic substrate with microcracks in the walls, the washcoat colloidal dispersion is free of soluble inorganic constituents and the particles do not fill the microcracks so as to prevent undesirable increase in thermal expansion and corresponding decrease in thermal shock resistance.

Claims35

Dependent claims

A catalyst device comprising a porous catalyst support, the support consisting essentially of:

a multichannel substrate having porous walls defining the channels and a network of open pores distributed through the walls, the walls containing washcoat particles bonded to the walls, all of which particles are of colloidal particle sizes in the range of about 0.001-0.2 micrometers and selected from the group consisting of alumina, rare earth oxide, silica, and zirconia, over 50% of the washcoat particles being deposited within the pores on the surfaces thereof substantially throughout the walls, any other portion of the washcoat particles being deposited on the external surfaces of the walls, and the washcoat particles not filling any microcracks in the walls.

A method of washcoating a multichannel substrate having porous walls defining the channels and a network of open pores distributed through the walls, which consists essentially of the steps of:

(a) obtaining a flowable colloidal dispersion of oxide particles in a first evaporable liquid, the particles being wholly of colloidal particles sizes in the range of about 0.001-0.2 micrometers and selected from the group of consisting of alumina, rare earth oxide silica and zirconia;
(b) contacting the walls of the substrate with the colloidal dispersion to cause the colloidal dispersion to infiltrate substantially all of the open pores;
(c) removing the walls of the substrate, with colloidal dispersion contained thereon, from contact with substantially the remainder of the colloidal dispersion to provide within the pores on the surfaces thereof a quantity of the contained colloidal dispersion having over 50% of the particles in the contained colloidal dispersion, and two provide on the external surfaces of the walls any other portion of the contained colloidal dispersion having any minor portion of the particles in the contained colloidal dispersion;
and
(d) drying the infiltrated substrate to cause the first liquid to evaporate out of the substrate, to cause the over 50% of the particles to deposit on the surfaces of the pores, and to cause the any other minor portion of the particles to deposit on the external surfaces of the walls.

2 more elements

Dependencies are inferred from the claim text.

Pore impregnated catalyst device

Life of this patent

Pore impregnated catalyst device

Life of this patent

Abstract

Claims35