Nickel catalysts obtained from hydrotalcites by coprecipitation and urea hydrolysis for hydrogen production

Nickel hydrotalcites were subjected to synthesis using two methods: coprecipitation and urea hydrolysis. The thermal decomposition of the hydrotalcite precursors produced mixed oxides corresponding to the active phases or final catalysts. ecursors and the mixed oxides were characterized using atomic absorption spectroscopy (AA), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), CO2 temperature-programmed desorption (TPD-CO2), textural properties, and temperature-programmed reduction with hydrogen (TPR-H2). talysts were evaluated under conditions which simulate the autothermal reforming of ethanol toward the selective production of H2. The solids synthesized via urea hydrolysis revealed the best reduction activity (higher hydrogen consumption at lower temperature) and larger average pore sizes, leading to better catalytic performance (higher H2 selectivity). Superior catalytic performance is attributed to the production of smaller active phase particles, which are generated during the synthesis based on urea hydrolysis.