Abstract Catalysts for the oxidative purification of exhaust gases such as the exhaust gases from internal combustion engines, are prepared by applying a suspension whose solid content consists essentially of boehmite to a ceramic support body thereby forming an intermediate coating which is adapted to receive one or more metals of the platinum group or alloys thereof in finely divided form. The thus treated support body is thereafter heated. The coating suspension also can contain dissolved aluminum nitrate. The intermediate coating of boehmite on the support body is converted to active aluminum oxide prior to impregnation with one or more metals of the platinum group or alloys thereof in finely divided form or the conversion can take place after such impregnation, for example, by heating upon exposure to the hot exhaust gases of an internal combustion engine.
METHOD FOR PREPARING A CATALYST FOR THE OXIDATIVE PURIFICATION OF EXHAUSTS GASSES WHICH COMPRISES APPLYING A SUSPENSON WHOSE SOLID CONTENT CONSISTS ESSENTIALLY OF BOEHMITE TO A CERAMIC SUPPORT BODY, FOLLOWED BY A FIRST HEAT TREATMENT AT 100* TO 300*C AND A SECOND HEAT TREATMENT AT 450* TO 600*C, IMPREGNATING THE SO COATED SUPPORT BODY BEFORE OR AFTER THE SECOND HEAT TREATMENT WITH AN AQUEOUS SOLUTION CONTAINING AT LEAST ONE SALT OF AT LEAST ONE METAL OF THE PLATINUM GROUP AND THEREAFTER REDUCING THE METAL OR METALS OF THE PLATINUM GROUP AND TO THE METALLIC STATE BY REDUCTION WITH HYDROGEN.
Claim 2
Dependent Claim
99 words
METHOD FOR PREPARING A CATALYST FOR THE OXIDATIVE PURIFICATION OF EXHAUSTS GASSES WHICH COMPRISES APPLYING A SUSPENSON WHOSE SOLID CONTENT CONSISTS ESSENTIALLY OF BOEHMITE TO A CERAMIC SUPPORT BODY, FOLLOWED BY A FIRST HEAT TREATMENT AT 100* TO 300*C AND A SECOND HEAT TREATMENT AT 450* TO 600*C, IMPREGNATING THE SO COATED SUPPORT BODY BEFORE OR AFTER THE SECOND HEAT TREATMENT WITH AN AQUEOUS SOLUTION CONTAINING AT LEAST ONE SALT OF AT LEAST ONE METAL OF THE PLATINUM GROUP AND THEREAFTER REDUCING THE METAL OR METALS OF THE PLATINUM GROUP AND TO THE METALLIC STATE BY REDUCTION WITH HYDROGEN.
Claim 3
Dependent Claim
37 words
Method of claim 1 wherein a suspension of boehmite containing dissolved aluminum nitrate is applied to the support body and the latter is then heated in said first heat treatment at a temperature between 200* and 200*C.
Claim 4
Dependent Claim
17 words
Method of claim 2 wherein the suspension contains 15 wt-% boehmite and 10 wt-% dissolved aluminum nitrate-nonahydrate.
Claim 5
Dependent Claim
24 words
Method of claim 2 wherein the suspension is held for about 1 hour at about 95*C prior to its application to the support body.