Effect of WO_x over Ni/hydrotalcite catalysts to produce hydrogen from ethanol

The effect of WO_x over Ni-hydrotalcite catalysts to produce H2 by ethanol steam reforming was studied. The catalysts were characterized by N2 physisorption (BET area), X-ray diffraction, Infrared and UV-vis spectroscopies. The W concentration ranged from 0.5 to 3 wt%. As W concentration increased, the intensity of XRD reflections of the Ni catalysts decreased. The porous structure of the materials consisted of parallel layers with a monomodal mesoporous distribution. The surface groups detected by IR were: -OH, Al-OH, Mg-OH, W=O and CO₃^2-. UV-vis results suggested that Ni²⁺ ions were substituted by W ions. The catalytic evaluations were made in a fixed bed reactor using a water/ethanol mol ratio of 4 at 450°C. Catalysts with low loadings of W (0.5 and 1%) showed the highest H₂ production and stability. W promoted the conversion of ethanol towards hydrogen in the case of the Ni-hydrotalcite catalysts. The reaction products were; H ₂, CO₂, CH₃CHO, CH₄ and C ₂H₄. The catalysts did not produce CO.