| abstract |
Compositions comprising iridium and at least one additional metal, preferably platinum, are disclosed in which the iridium and the additional metal or metals are present on a refractory support as highly dispersed polymetallic clusters. The metallic atoms in a cluster are separated by distances of about 2.5 to 4.0A. The degree of coverage of the surface of said refractory support by said polymetallic clusters is lower than about 10% and frequently lower than about 1%. The compositions are useful as hydrocarbon conversion catalysts, and iridiumplatinum catalysts containing a halogen moiety are especially useful for promoting naphtha reforming reactions. |