Showing papers by "Elisabete Moreira Assaf published in 2018"

NiMgAlCe Catalysts Applied to Reforming of a Model Biogas for Syngas Production

Abstract: Hydrotalcite mixed oxide catalysts promoted with CeO2 containing nickel as the active phase were employed in the reforming of a free of contaminants model biogas. Catalysts were characterized using techniques such XRD, H2-TPR, CO2-TPD, Raman spectroscopy and TEM analyses. They showed a good performance along the 6 h of testing. Despite the drastic conditions for catalysts evaluation (low temperature and excess of CH4) that facilitate carbon deposition, the Ni 10 wt% catalyst showed a deposition rate similar to catalyst evaluated in softer conditions already reported in literature. The Ni 5 wt% spent catalyst showed the lowest carbon deposition rate among the three catalysts tested. Together with carbon filaments, the Ni 15 wt% catalyst featured the presence of encapsulating and coating carbon and they both would lead to deactivation, as attested by its oscillating activity behavior.

Synthesis of NiO/Y2O3/ZrO2 Catalysts Prepared by One-Step Polymerization Method and Their Use in the Syngas Production from Methane

Abstract: In this work, the production of Syngas (H2/CO) from oxidative reforming of methane (ORM) and partial oxidation of methane (POM) over NiO/Y2O3/ZrO2 catalysts was studied. The nickel concentration was varied (ranging from 0 to 40 wt.%) aiming to optimize the performance in ORM and POM reactions; these reactions were carried out at 750°C and 1 atm for 6 hours. The catalysts were prepared by the one-step polymerization method (OSP) and characterized by different techniques. This method led to production of materials of smaller crystallite size than others of similar composition prepared under other methods; the catalysts presented good nickel dispersion, well-defined crystalline structure, and well-defined geometrical morphology. Additionally, the OSP method was advantageous because it was carried out in a single calcination step. The catalyst containing 20% wt. of nickel (20Ni20YZ sample) showed the highest methane conversion, high selectivity to H2 and CO, low carbon deposition rates, and, curiously, the best geometric morphology. The results of this paper also demonstrated that the nickel concentration in the mixture strongly influenced the morphology of the catalysts; therefore, the morphology also influenced the catalytic performances during the Syngas production reactions.