US 5,294,580 A · Method for making alloyed catalysts

Abstract

Adjustment of the noble metal catalytic activity in the production of noble metal alloyed catalyst preparation using alloying metals capable of multiple valence states improves the alloying metal loading. A noble metal is precipitated from a liquid onto a support. Prior to the addition of an alloying metal which is capable of a low valence state having low solubility and a high valence state having high solubility, the catalytic activity of the noble metal precipitate is reduced. Reduction is accomplished by adjusting the temperature and/or pH of the liquid such that a minimal amount of the alloying metal will be converted from the lower to the higher valence state. By maintaining the alloying metal in the lower valence state, a greater amount of the alloying metal which has been dissolved into the liquid is precipitated onto the support, thereby attaining high loadings, reducing waste of the alloying metal, making the loadings predictable, and making the waste liquid more environmentally sound.

Claims10

Dependent claims

A method for making a noble metal alloyed catalyst using a noble metal having a catalytic activity, and at least one alloying metal, wherein at least one of the alloying metals has at least two valence states with the alloying metal in a low valence state having a solubility in a liquid and having a higher valence state with a higher solubility in the liquid, which comprises:

a. intimately contacting a supporting and a noble metal compound in the liquid;
b. precipitating the noble metal, wherein said noble metal precipitate adsorbs onto said support;
c. reducing the catalytic activity of the noble metal precipitate to inhibit said noble metal precipitate from converting the valence state of the alloying metal to the higher valence state;
d. introducing the soluble alloying metal compound into said liquid to form an alloying metal solution;
e. precipitating said alloying metal, wherein said alloying metal precipitate adsorbs onto said support;
and
f. calcining said support with the noble metal and alloying metal precipitates to form an alloyed catalyst;
whereby said soluble alloying metal compounds introduced to said liquid subsequent to the reduction of the catalytic activity of the noble metal precipitate.

5 more elements

Dependencies are inferred from the claim text.

Method for making alloyed catalysts

Life of this patent

Method for making alloyed catalysts

Life of this patent

Abstract

Claims10