Formation of small rhodium metal particles on the surface of a carbon support

Supercritical n-butane isomerization over the solid acid catalysts sulfated zirconia, TiO2-supported H4[Si(W3O10)4] · xH2O (Keggin-type heteropoly acid), and H-mordenite is studied in a flow reactor. The critical parameters of n-butane are calculated for a wide range of reaction conditions. Changing from gaseous n-butane to supercritical n-butane markedly extends the lifetime of the catalysts. Under supercritical conditions, the activity and selectivity of the catalysts are invariable, provided that the density of the reaction mixture is in the vicinity of the critical density of n-butane. After the catalysts are deactivated in the gas medium, they can be partially or completely reactivated in the supercritical fluid.