Hydrogen production by catalytic decomposition of selected hydrocarbons and H_2O dissociation over CeZrO_2 and Ni/CeZrO_2

摘要

Presented paper deals with the catalytic decomposition of hydrocarbons (methane and toluene) in the aspect of H_2 production and types of obtained carbon deposits. The catalyst used in our studies was nickel supported on ceria-zirconia (Ni/CeZrO_2). The aim of this work was to investigate the reactivity of obtained carbon deposits with H_2O. Both issues are of great importance for determining the mechanisms of carbon deposits formation and their suppression during steam reforming reaction.Our studies revealed that depending on the temperature, CH_4 decomposition over Ni/ CeZrO_2 leads to carbon nanotubes (CNTs), whereas C_7H_8 decomposition yields pyrolytic carbon. Hydrogen production was found to be higher for CH_4 decomposition. Both types of carbon deposits (filamentous and pyrolytic) were found to be very reactive with H_2O, which is due to their activation by the ceria-zirconia support.Catalytic tests of hydrocarbon decomposition and H_2O dissociation were carried out in the temperature-programmed mode and isotherms, and were supported by the in situ reflectance FT-IR measurements. Obtained carbon deposits were characterized using high-resolution transmission electron microscopy (HRTEM).