Perovskite oxide structured (YBCO) has been Ðrst pre-YBa 2 Cu 3 O 7vx pared by carbonate precipitation and then modiÐed with palladium or ruthenium by impregnation on the perovskite oxide, while cobalt was co-precipitated simultaneously in the same pH range with perovskite oxide. After characterization the catalysts were used in the temperature range 300È450¡C, in the pressure range 1È9 atmospheres and for ratios in the range 1È4 in a H 2 /CO di †erential plug Ñow reactor for the hydrogenation of carbon monoxide to give hydrocarbons. The perovskite oxide (YBCO) 20% (w/w) and doped 2% (w/w) cobalt oxide catalyst were prepared by the wet chemical method from their nitrate solutions and oxidized at 950¡C. Perovskite oxide (Dursun, G. & Winterbottom, J. M., J. Chem. T echnol Biotechnol. 63 (1995) 113È16) was also doped with palladium and ruthenium metal by impregnation followed by oxidation at 250¡C. The catalysts prepared were characterized by using Temperature-Programmed Reduction (TPR) to observe the reduction temperature and also to measure total and metal surface area. The modiÐed perovskite oxide on alumina, ruthenium-and cobalt-doped catalysts, has been shown to give a better conversion and also selectivity towards saturated hydrocarbons compared with palladium-doped catalyst. The temperature e †ect of these catalysts is more consistent, giving a steady increase of conversion with increasing temperature. Although increase of pressure increases the conversion, it causes very little change in product distribution. The activation energy of palladium-and ruthenium-doped, and cobalt co-precipitated catalysts for the reaction has been measured to be 55 kJ mol~1, 75 kJ mol~1 and 50 kJ mol~1 respectively. A general rate equation of the form has been observed and found r \ k[H 2
]m[CO]n to be applicable at the pressures and temperatures used for the catalytic system studied and found to be m + 1É0 for palladium-doped, m + 1É2 for rutheniumdoped and m + 0É95 for cobalt co-precipitated catalysts as n becomes zero or negligibly less than zero. The mechanism of reaction to produce hydrocarbons from syngas has been deduced from the results. It appeared that the carbon monoxide insertion mechanism has been more evident for palladium-doped catalysts whereas the carbide mechanism plays the main role for the rutheniumdoped and cobalt co-precipitated catalysts.