Methane reforming with carbon dioxide over a Ni/ZiO₂-SiO ₂ catalyst: Influence of pretreatment gas atmospheres

Carbon dioxide reforming of methane to synthesis gas was studied over Ni/ZrO2eSiO2 catalyst under different pretreatment atmospheres. Characterization using powder X-ray diffraction, H₂ temperature-programmed reduction, H₂ temperature-programmed hydrogenation, TG/DTA, XPS, Raman spectra and transmission electron microscopy techniques revealed that gas atmospheres employed in the catalyst pretreatment have a significant influence on the catalytic performance. The helium-pretreated catalyst was found to be the most suitable catalyst for this application, showing the improved catalytic performance. More specifically, helium pretreatment facilitated the generation of welldistributed active metal sites while the heterogeneity of Ni components upon H₂ pretreatment degraded catalytic activity of metal sites considerably. Pretreatment under CO atmosphere resulted in the formation of carbon encapsulated metal species thus causing catalyst deactivation severely. Inefficient reduction under CH4 activation and the presence of a great amount of carbonaceous species, disfavor the production of synthesis gas during the dry reforming.