Low temperature ethanol steam reforming for process intensification : new Ni/MxO-ZrO2 active and stable catalysts prepared by flame spray pyrolysis

Steam reforming of hydrocarbons is a mature technology and its implementation on other substrates such as bio-ethanol appears as a ready opportunity to produce H2 from renewable sources. The Low Temperature Ethanol Steam Reforming (LT-ESR, 300–500 °C) could be a really efficient technology from the energetic point of view. However, deactivation by coke deposition remains the biggest issue, due to inefficient carbon gasification by steam in such low temperature range. We demonstrated the feasibility of the process at low temperature taking into account both activity and deactivation issues. The attention was focused on the addition of basic promoters and on the development of an unconventional preparation procedure, in comparison with a traditional precipitation/impregnation route, to improve stability and activity. Therefore, in this work several catalysts were studied, differently promoted by alkali and alkali earth oxides (CaO, MgO, K2O) using a non conventional doping method. H2 yield and selectivity to CO demonstrated tightly related to the promoter adopted. Flame Spray Pyrolysis synthesis of nickel nanoparticles stabilized in a zirconia matrix (Ni/MxO-ZrO2) was performed, obtaining more stable catalysts toward deactivation by coking with respect to the analogous prepared by traditional precipitation/impregnation. The effect of the doping using a scalable one-pot technique was investigated by means of characterization of fresh catalysts and activity testing. Catalyst resistance toward deactivation was studied by SEM-EDX, TEM, Raman spectroscopy and temperature programmed analysis. Among the promoters, CaO and K2O showed the best performance, producing a reformate with low CO/CO2 ratio and, thus, leading to higher H2 yield with consequent lower impact on H2 purification in an integrated process. K2O deeply modified the chemical behaviour of the catalyst allowing to achieve a significant H2 production also at very low temperature (300 °C).