Renewable hydrogen from glycerol reforming over nickel aluminate-based catalysts

摘要

Nickel aluminate (NiAl2O4) was synthesized by citrate method and used as a precursor for supported Ni catalysts. This bulk sample as well as an alumina-supported NiAl2O4 and a dual catalytic system obtained by its simple and straightforward physical mixture with alumina were investigated on glycerol reforming at different water:glycerol molar ratio conditions. All catalyst precursors and the reduced catalysts made thereof were characterized by XRF, porosity, H-2-TPR, powder XRD and temperature-resolved XRD. Spent catalysts were complementarily analyzed by TPO/TGA-MS and FE-SEM in order to infer on deactivation process. NiAl2O4 precursor structure rendered highly active systems accomplishing a level of glycerol conversion to gaseous products roughly equivalent to glycerol global conversion. Therefore, hydrogen and CO2 were the main products obtained, reaching hydrogen yields usually higher than 80% with respect to the theoretical maximum production. The way NiAl2O4 phase is settled in catalyst formulation (bulk, supported or physically mixed) revealed an important influence on catalyst deactivation. Deactivation was associated with the formation of carbon filaments as no other type of carbon species, more or less reactive, could be identified. (C) 2016 Elsevier B.V. All rights reserved.