Multi-layer supported catalysts of the platinoid family

Claim 2

A MULTI-LAYERED SUPPORTED CATALYST COMPRISING A METAL OR METAL ALLOY SUPPORT COVERED, AT LEAST PARTIALLY, BY A LAYER OF AT LEAST ONE METAL ALUMINIDE, WHEREIN THE METAL OF SAID METAL ALUMIDE IS SELECTED FROM THE GROUP CONSISTING OF COBALT, NICKEL, IRON, CHROMIUN AND MIXTURES THEREOF: SAID METAL ALUMINIDE LAYER COVERED WITH A LEAYER OF A-ALUMINA AT LEAST 10 MICRONS THICK AND SAID A-ALUMINA LAYER SUPPORTING A CATALYTIC SURFACE LAYER OF A METAL, METAL OXIDE OR METAL SULFIDE, WHEREIN SAID METAL OF SAID CATALYTIC SURFACE LAHYER IS A METAL SELECTED FROM THE PLATINOID FAMILY OR MIXTURES THEREOF.

Claim 3

The catalyst of claim 1 wherein the metal or metal alloy support is selected from the group consisting of iron, steel, ferronickels, nickel, chromium-nickels, ferritics, austenitics, stainless steels, cobalt-chromium and cobalt-nickel-chromium alloys.

Claim 4

The catalyst of claim 1 wherein the metal aluminide layer has a thickness of from 5 microns to about 1 mm.

Claim 5

The catalyst of claim 1 wherein a layer of gamma or eta alumina having a specific area of between 100 and 400 meters2 per gram is disposed over said Alpha -alumina layer and supports said catalytic surface layer.

Claim 6

The catalyst of claim 4 wherein said active oxide layer is from 10 to 25 microns thick.

Claim 7

The catalyst of claim 1 wherein the metal aluminide layer is a nickel or cobalt aluminide having a thickness of from 5 microns to about 1 mm, and having a layer of gamma or eta type alumina deposited over said Alpha -alumina layer and supporting said catalytic surface layer.

Claim 8

The catalyst of claim 6 wherein said gamma or eta type alumina layer has a thickness of from 10 to 25 microns.

Claim 9

A catalytic structure comprising a stack of the catalysts of claim 1 within a rigid block, and the support of said catalyst being flat parts made of metal or expanded metal alloy.

Claim 10

A process for making the multi-layered supported catalyst of claim 1 which comprises depositing the metal aluminide on said metal or metal alloy support by contacting and heating said support with a cement containing nickel aluminide and alumina, depositing an Alpha -alumina layer on said aluminide layeR by contacting said aluminide layer with a solution of an alkaline aluminate to form a layer of hydrated alumina thereon, removing said layer from said solution and heating said hydrated alumina layer to above 980* C to convert said hydrated alumina into Alpha -alumina, and depositing said catalytic surface layer thereon.

Claim 11

The process of claim 9, which further comprises depositing a layer of gamma alumina on said Alpha -alumina layer before depositing said catalytic surface layer thereon by contacting said Alpha -alumina layer with a solution of an alkaline aluminate to form a layer of hydrated alumina thereon, removing said layer containing said hydrated alumina from said solution and applying heating to about 800*C to convert said hydrated alumina to gamma alumina.

Claim 12

The process of claim 10 wherein a thin layer of alumina is formed on said metal aluminide layer before depositing said layer of Alpha -alumina thereon by heating said metal aluminide layer in the presence of an oxidizing atmosphere.

Claim 13

The process of claim 9 wherein the metal alloy support is stainless steel which is covered prior to forming said metal aluminide layer thereon with a nickel layer and heating said nickel covered stainless steel in a hydrogen atmosphere to diffuse said nickel into the stainless steel support.

Claim 14

A process for preparing a catalyst structure containing a plurality of stack spaced layered supported catalysts, each of said catalysts having a support of expanded stainless steel, coated with a layer of at least one metal aluminide of nickel or cobalt having a thickness of from 5 microns to about 1 mm, said aluminide layer having a coating of Alpha -alumina at least 10 microns thick, said Alpha -alumina having a coating of an active layer of eta or gamma alumina and at least one catalytic layer thereon, comprising coating expanded stainless steel supports with a layer of nickel, assembling said nickel covered stainless steel supports into a stack with a spacing weld wire between each support, heating the assembled supports in a hydrogen atmosphere to diffuse said nickel therein and weld said assembly together, depositing a metal aluminide layer on said supports by contacting and heating said support with a cement containing nickel aluminide and alumina, depositing an Alpha -alumina layer on said aluminide layer by contacting said aluminide layer with a solution of an alkaline aluminate to form a layer of hydrated alumina thereon, removing said layer from said solution and applying heating to above 980*C to convert said hydrated alumina into Alpha -alumina, repeating said treatment with said alkaline aluminate and heating to a temperature of about 800*C to produce a layer of gamma alumina, and depositing a catalytic surface layer thereon.

Claim 15

A process for preparing a catalyst structure containing a plurality of stack spaced layered supported catalysts, each of said catalysts having a support of expanded stainless steel, coated with a layer of at least one metal aluminide of nickel or cobalt having a thickness of from 5 microns to about 1 mm, said aluminide layer having a coating of Alpha -alumina at least 10 microns thick, said Alpha -alumina having a coating of an active layer of eta or gamma alumina and at least one catalytic layer thereon, comprising coating expanded stainless steel supports with a layer of nickel, assembling said nickel covered stainless steel supports into a stack with a spacing weld wire between each support, heating the assembled supports in a hydrogen atmosphere to diffuse said nickel therein and weld said assembly together, depositing a metal aluminide layer on said supports by contacting and heating said support with a cement containing nickel aluminide and alumina, depositing an Alpha -alumina layer on said aluminide layer by contacting said aluminide layer with a solution of an alkaline aluminate to form a layer of hydrated alumina thereon, removing said layer from said solution and applying heating to above 980*C to convert said hydrated alumina into Alpha -alumina, repeating said treatment with said alkaline aluminate and heating to a temperature of about 800*C to produce a layer of gamma alumina, and depositing a catalytic surface layer thereon.

Claim 16

The process of claim 9 wherein the metal alloy is Inconel.

Claim 17

The process of claim 13 wherein the assembled supports are welded together by heating in a neutral gas or in a vacuum.