Catalyst composition and a method for its preparation

Details Catalyst composition and a method for its preparation Catalyst composition and a method for its preparation

1991-09-05

1993-04-20

Dees, Carl F.

Catalyst, solid sorbent, or support therefor: product or process

Having foreign or diverse function

With structure having utility in addition to support or carrier

502 1, 502 5, 502527, B01J 3500, B01J 3734

Patent

active

052043029

ABSTRACT:
A multi-layered catalyst on a metal substrate and a method for its preparation is provided. The catalyst includes a substrate, an adhesive sublayer whose improved adhesion to the substrate is obtained by the formation of a diffusion layer between the substrate and adhesive layer, a catalytically active layer deposited on the adhesive sublayer characterized by a smooth compositional gradient of the catalytically active component such that the catalytically active layer ranges from substantially 0.0 wt % at the adhesive sublayer interface to substantially 100 wt % at the outermost portion of the catalytically active layer and a porous layer containing at least the catalytically active component. An activator coating can be applied to the porous layer. The catalyst is prepared by plasma spraying a thermally reactive powder onto the substrate to form the adhesive sublayer, whereby the heat generated by the thermally reactive powders causes diffusion of the sublayer into the substrate and a diffusion bonded layer is formed resulting in a strong adhesion of the sublayer to the substrate, subsequently introducing at least alumina and a second powder into a plasma torch at separately controllable variable feed rates and co-depositing alumina and the second powder, adjusting the relative feed rates of alumina and second powder into the plasma torch such that a catalytically active layer with a smooth compositional gradient is achieved, whereby the alumina content of the catalytically active layer ranges from substantially 0 wt % at the adhesive sublayer interface to substantially 100 wt % at the uppermost portion of the catalytically active layer, subsequently introducing at least alumina and an additional metal carbonate or hydroxide into the plasma torch; and co-depositing a porous layer of at least alumina and the additional metal carbonate or hydroxide, whereby the metal carbonate or hydroxide decomposes with a release of gas or vapor resulting in an outer coating with a high surface area.

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