Monolithic reactors for environmental applications: A review on preparation technologies

A catalyst comprising a metal or alloy substrate, an oxidation resistant coating applied to the substrate, the coating comprising aluminum metal powder in a ceramic binder, a high surface area catalytic washcoat over the oxidation resistant coating and a catalytically active material, eg a platinum group metal, associated with the washcoat

Catalyst comprising a metal substrate

There has thus been provided a highly efficient metal-ceramic catalytic combustor for a gas turbine/catalytic combustor assembly. The catalyst zone is formed of a high temperature resistant metal wire mesh, e.g., palladium coated tungsten or ferritic stainless steel screen, e.g., 40 mesh, which is aluminized with metallic aluminum, and heated to convert the outermost layer of aluminum to aluminum oxide and encourage the diffusion of the inner layer of aluminum into the body of the metal wire, desirably forming a thin metal/aluminum alloy layer. The outer surface because of the Kerkendall Effect is porous and readily accepts and strongly bonds to a metal oxide coat, e.g., a magnesia/alumina, or magnesia/alumina/yttria, or barium oxide/alumina, or barium oxide/alumina/yttria wash coat. There may also be included a catalyst deposited on the ceramic outer coat, e.g., a noble metal catalyst, for enhancement of the combustion of an air/fuel mixture. Because the metals from which the wire mesh is formed all have melting points above the maximum temperature of operation, i.e., 2700° F., the screen itself has significant tensile strength at temperature.

High temperature combuster

A metal support for a catalyst is disclosed, which is suitable for use in a catalytic converter for an automobile. The support generally does not interact with the catalyst, even at high temperatures, and the catalyst therefore retains its activity for a long period. The support includes a base metal containing chromium, aluminum and silicon, the remainder of the base metal being mostly iron. The specific percentages of chromium, aluminum, and silicon in the base metal can be varied according to a formula. The base metal is coated with a layer of metallic aluminum. A catalyst is applied to the support, preferably by first coating the support with a layer of alumina, and then impregnating the alumina layer with a suitable combustion catalyst. The support can be rolled down to foil thickness. When formed as a foil, the support is particularly useful in making catalytic converters for automobiles. The formula disclosed shows how aluminum or silicon can be substituted for some of the chromium in the base metal. The invention therefore provides a catalyst support of relatively low cost.

Metal support for a catalyst

A laminated oxidation resistant catalyst element includes a metal alloy substrate such as a steel foil coated with a noble metal such as platinum. A ceramic washcoat such as alumina is applied over the noble metal and a catalyst is applied with the washcoat or individually during a subsequent application step. The noble metal prevents oxygen from contacting the metal substrate thereby preventing its degradation by oxidation reactions. The catalyst element is particularly suited for use in a catalytic reactor bed of an industrial gas turbine.

Laminated substrate for catalytic combustor reactor bed

An all metal, high temperature resistant, catalyst element is provided by plating or depositing a noble metal comprising platinum and/or palladium onto a base material which comprises primarily aluminum, chromium and iron. The nickel-free, aluminum containing base material appears to be of advantage for at least certain all metal catalyst element operations and also results in substantially lower first cost catalyst units.

Gerald L Brewer

Papers

Nickel-free, all metal, catalyst element