Process for preparing noble metal catalysts
AssigneeStamicarbon B.V.
InventorsAbraham van Montfoort, Joseph J. F. Scholten
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Abstract
The invention relates to a process for preparing active noble-metal catalysts on a carbon carrier. In particular, the process comprises adsorbing a salt of the catalytically active metal onto the carbon in an aqueous medium; hydrolyzing said salt to the oxide or hydroxide, by employing a basic reagent; and reducing said oxide or hydroxide to the metal.
Claims13
In a process for preparing active noble-metal catalyst on a carbon carrier by adsorbing at least one water-soluble salt of a catalytically active metal onto the carbon in an aqueous medium, by hydrolyzing said salt by treating the salt with a basic reagent to form the oxide or hydroxide, and by reducing said oxide or hydroxide to the metal, the improvement comprising employing an active carbon having an acid to neutral reaction in water and an internal surface area of at least 300 m.sup.2 /g and up to about 1000 m.sup.2 /g with a particle size between 1 and 60 microns and with an ash content that does not exceed 3.5% by weight, whose ratio between (1) the pore volume, of the pores between 20 to 1000A plug the pores exceeding 1000A and (2) the total pore volume of said particles lies between 0.6 and 1.0 whereby the hydrolysis of the noble metal salt and the reduction of the oxide or hydroxide formed thereby are carried out in a single processing step with liquid hydrolyzing and reducing agents.
In a process for the preparation of supported catalyst comprising treating at least one water-soluble salt or complex of a noble metal of Group VIII in the presence of a carrier with a base to form the oxide or hydroxide of said salt on the carrier and then reducing said oxide or hydroxide to form the free metal of the oxide or the hydroxide on said carrier, the improvement comprising using as a carrier an active carbon having a large internal surface area whose ratio between (1) the pore volumes of the macro pores plus the transition pores and (2) the total pore volume lies between 0.6 and 1.0, and dispersing the carrier in an aqueous solution of said salt;
- treating the carrier dispersion of the aqueous solution in a single step with (A) and (B) wherein (A) is a carbonate, or a bicarbonate of an alkali metal or ammonium and (B) is methanol, formic acid, formaldehyde, or mixtures thereof, thereby effecting (a) precipitation of said salt and adsorption of the salt onto the carrier and (b) reduction of the precipitate to the free metal.
Dependencies are inferred from the claim text.