Effect of EDTA in preparation of Ni catalysts toward a carbon-resistant ethanol reforming

Abstract

Ni supported catalysts were prepared by an EDTA complexing method with different EDTA/Ni molar ratios: 0, 0.5, 1 and 2. The catalysts were characterised by X-ray diffraction, adsorption-desorption isotherms of N2, infrared spectroscopy, thermogravimetric analysis, temperature programmed reduction and X-ray photoelectron spectroscopy. All the catalysts prepared with EDTA presented a decrease in the NiO particle size of around 60 % with respect to the sample obtained in the absence of a chelating agent. Besides, the EDTA/Ni = 1 catalyst corresponding to the complete Ni chelation showed a Ce3+/Ce4+ high surface ratio. The greater extent of surface reduction of CeO2 suggests changes in the NiO-CeO2 interaction induced by the presence of the chelating agent during preparation. The NiEDTA(1) sample showed the best performance in the ethanol steam reforming reaction at 650 °C. An ethanol conversion of 100 % was reached after seven hours in reaction with a high yield of hydrogen (5.4 mol H2/molC2H5OH) and a low carbon deposition rate (1.4 mgC/gcat h).