Abstract

CALAFAT, Álvaro; ALDANA, José  and  SANCHEZ, Nora. Thermal catalytic decomposition of methane over unreduced Ni/SiO₂ and Ni/Al₂O₃ catalysts. Rev. Téc. Ing. Univ. Zulia [online]. 2012, vol.35, n.2, pp.162-169. ISSN 0254-0770.

The thermo catalytic decomposition (TCD) of methane at 823-973 K was investigated over unreduced 30 wt% Ni/Al₂O₃ and Ni/SiO₂ catalysts. The catalytic activities of the unreduced catalysts were compared with those obtained for the catalysts pre-reduced with H₂. Methane decomposition was studied by the thermogravimetric method, monitoring the mass change of the catalyst due to carbon deposition. The initial specific rates of carbon formation (r_c,i), and as a consequence the catalyst activity, on the unreduced catalysts were higher than those for the pre-reduced catalyst. The differences observed seemed not to be related to the particle size of the nickel species, determined from X-raydiffraction analysis (XRD). Arrhenius plots of the initial rates indicated that the rate-determining step for carbon formation is independent of whether the catalysts are pre-reduced or not. Differences in catalytic activity between unreduced and pre-reduced catalysts are probably due to heat coupling effects during the reduction of NiO by CH₄, H₂ and deposited carbon at the beginning of the decomposition of methane.

Keywords : methane decomposition; Ni catalyst; catalyst reduction; metal particle size; thermogravimetric analysis.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )