Abstract
Activated carbon and carbon with Cu, Ni and Pt were used in this investigation. The metals were loaded on carbon by impregnation and heated in a stream of helium. The crystalline phases of metals were obtained by x-ray diffraction analysis. The adsorption of benzene was carried out at elevated temperatures. The catalytic activity of the prepared samples was tested in cyclohexene conversion. The x-ray analysis of the activated samples showed metallic copper, and nickel. Platinum not appeared on x-ray diffractogram due to its small amount. The adsorptive capacity of carbons decreased in the order: (C > Pt/C > Ni/C > Cu/C). In case of cyclohexene conversion, three sets of experiments were performed for each catalyst, by increasing, decreasing and at constant temperature. The activity of the catalysts was decreased in the following order; (Ni/C > Pt/C > C > Cu/C).
This trend was observed either by increasing or decreasing the reaction temperature. At constant reaction temperature, successive additions of cyclohexene led to a gradual change in their activity and selectivity. The number of active sites was calculated using thiophene as a poison and it was found to be amounting (9 - 13.7) 10(19) centres per gram catalyst.