Abstract: A method for testing a plurality of catalyst formulations and determining, from the plurality, a preferred catalyst formulation to be used in a catalyst device for treating a particular reactant stream is provided. The method comprises defining the cell characteristics of a catalyst device, providing a test monolith comprising a plurality of cell channels having cell characteristics equivalent to the cell characteristics of the catalyst device for which the preferred catalyst formulation is being determined, applying a plurality of different catalyst formulations on the cell channels of the test monolith, contacting a test reactant stream to all channels of the test monolith under flow conditions equivalent to the flow conditions under which the catalyst device is intended to be used, detecting comparative catalytic activity occurring at each formulation during said contacting step, and determining, from the detected activity, the preferred catalyst formulation for the catalyst device.

Abstract: Improved platinum group three-way catalyst composition comprising (a) a high temperature catalyst support material, (b) a low temperature catalyst support material, (c) at least one platinum group metal, and (d) a metal additive effective for the suppression of hydrogen sulfide emissions, that is disposed in a separate layer either under or over a layer comprising the constituents (a), (b), and (c), or in the same layer as the constituents (a), (b), and (c). When the metal additive is disposed in the same layer as the constituents (a), (b), and (c), (d) the metal additive is disposed in a physical structure that is segregated from the remaining components in the layer.

Abstract: A process for chemically converting surface hydroxyl groups present on an uminum oxide supported rhodium catalyst that is suitable for use as an automotive catalyst in controlling automotive exhaust emissions is disclosed. The process includes converting the hydroxyl groups on the aluminum oxide supported catalyst by reacting the aluminum oxide support with an alumina modifier which comprises an inorganic compound containing the cation Y, wherein Y is either an alkali metal or an alkaline earth metal. This process involves replacing the hydroxyl groups on the aluminum oxide support with OY groups to resist the oxidative conversion of supported metallic rhodium Rh.sub.x .sup.(O) to Rh.sup.(I). An associated catalyst suitable for use in automotive catalytic converter technology for environmental protection is provided.

Abstract: A process for chemically removing surface hydroxyl groups present on an aluminum oxide supported rhodium catalyst that is suitable for use as an automotive catalyst in controlling automative exhaust emissions is disclosed. The process includes removing the hydroxyl groups from the aluminum oxide supported catalyst by silation at a temperature preferably equal to or greater than about 450 K so that the conversion of active metallic rhodium Rh.sub.x (0) to oxidized rhodium species Rh.sup.(I) cannot substantially occur by reduction of the active hydroxyl groups. The silation is carried out by exposing the aluminum oxide supported rhodium catalyst to a gas phase alkylhalosilane. Subsequent to the silation, evacuation of the alkylhalosilane treated aluminum oxide supported rhodium catalyst is effected to remove substantially all unreacted alkylhalosilane. An associated catalyst suitable for use in automotive catalytic converter technology for environmental protection is also provided.