Nickel aluminate spinel-derived catalysts for the aqueous phase reforming of glycerol: Effect of reduction temperature

Abstract

Bulk nickel aluminate (NiAl2O4) was synthesised by co-precipitation at a Ni/Al mole ratio of 1:2 (stoichiometric ratio). The prepared sample was reduced at different temperatures, in the 300 to 850 ºC range, and obtained assays were analysed by a wide range of analytical techniques (XFR, XRD, H2-chemisoprtion, H2-TPR, DRS UV-vis NIR, FTIR, 27Al MAS NMR, NH3-TPD, CO2-TPD, TPO) and tested for the APR of glycerol. The spinel precursor allowed the formation of small and stable Ni particles (< 14 nm) upon reduction with good performance in the APR of glycerol (NiAl-850 93% conversion, 57% conversion to gas, at 250 ºC/45 bar and WHSV 24.5 h-1). Hydrogen was the main gaseous product and the activation temperature did not substantially alter selectivity to gaseous products; however, selectivity to intermediate oxygenated liquid compounds was substantially modified. Overall, glycerol dehydrogenation route was dominant at high reduction temperature. The good stability of the spinel led to stable H2 yield in the long-term runs (50 hours) and proved potential to be used in the APR of glycerol.