Parameters evaluation reform in ethanol: oxidative and steam

In face of current trends in nowadays energy demands, the world is in need of new technologies able to provide sustainable, renewable and nonpolluting energy. Hydrogen production for fuel cells from ethanol has shown to satisfy these requirements. In this way, the present work dealt with hydrogen production from steam reforming and oxidative steam reforming reactions for fuel cells as a form of renewable and pure energy. For that purpose, two catalysts were synthesized by wet impregnation: Cu/Ni/CeO₂ and Cu/Ni/Na₂O/Nb₂O₅. These catalysts were characterized by several techniques, namely: atomic absorption, X-ray diffraction (XRD), temperature programed reduction (TPR), temperature-programed ammonia desorption (TPD-NH₃), textural analysis, thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XDR and TPR analyses showed interactions between the active phases in the Ce supported catalyst and between the support and Cu in the catalyst supported in Nb²O₅. The acidity characterization (TPD-NH₃) revealed acidity in both catalysts. This acidity was greater in both supports before impregnation of the catalysts. Textural analysis revealed CeO₂ as a mesoporous material and highly porous in comparison with Nb₂O₅, which showed smaller area and micropore characteristics. These textural properties influenced the SEM analyses, since the catalyst Cu/Ni/CeO₂ has presented higher dispersion, i.e., less cluster formation, and also masked the appearance of metallic particles. The catalytic tests performed with Cu/Ni/CeO₂ in absence of oxidative atmosphere had H₂, CO₂ and acetone as the main products, due to the great support influence. In the presence of oxygen, the products CO, CO₂, CH₄ and acetaldehyde were found in greater proportions. The catalyst Cu/Ni/Na₂O/Nb₂O₅ did not present acetone among its products, but favored the formation of CO, CO₂, CH₄, H₂ and acetaldehyde in greater proportions. Nevertheless, at 400 °C, the product of higher selectivity was ethane, what led to a possible mechanism for this catalyst in which this product is involved. The catalyst supported in Nb₂O₅ presented some instability, since great formation of coke was observed over the catalyst. Some tests were performed without previous activation of the catalysts. These tests did not presented high conversion, but products selectivity was good relative to the other tests performed with previous activation of the catalysts. (author)