Safety in the preparation of multimetallic catalysts

Abstract

THERE is presently an extensive research effort in the field of catalysis concerned with alloy systems. Many researchers are preparing and characterising unsupported systems in order to study the metal phase in the absence of the support. A classical approach to doing this is that of simultaneous chemical reduction of the salts of a given alloy system in aqueous solution. Such reducing agents as hydrazine or sodium borohydride are frequently used. During the course of our work we found that the reduction of ruthenium salts with borohydride solutions gave a ‘metal powder’ which, when dried, violently exploded on touching it with water and sometimes by simple stimulation with a spatula. Under certain conditions a very unstable and poorly characterised ‘ruthenium hydride’ is apparently formed. A safer alternative technique is to use aqueous solutions of hydrazine for the chemical reduction of ruthenium-containing solutions.