Hydrothermal stability improvement of NiPt-containing gamma-Al2O3 catalysts tested in aqueous phase reforming of glycerol/water mixture for H-2 production

The hydrothermal stability of Ni and NiPt-containing gamma-Al2O3 catalysts in aqueous phase reforming (APR) of glycerol/water mixture (C3H8O3/H2O, 10% w/w) was investigated putting in evidence the influence of the preparation method; sol gel in basic medium (SGB) and impregnation on an in-house prepared sol gel gamma-Al2O3 support (SGI). All developed catalysts were characterized by ICP-AES, TPR-H-2, in-situ heating XRD-O-2, DSC/TG-N-2/O-2 and ex situ reduction of XRD-H-2 N-2 physisoption and TEM techniques. The results indicate that SGI method and calcination treatment at 750 degrees C were crucial in extending the catalytic useful life of NiPt-containing gamma-Al2O3 catalysts, resulting in an adequate distribution of Ni Pt metallic particles and good stability of gamma-Al2O3 support against the severe hydrothermal conditions of APR process. The SGI method led to form stable NiPt catalysts with relatively big Ni particles and stable hydrothermal properties of gamma-Al2O3 support, while the SGB catalysts exhibited well-dispersed Ni particles but unstable catalytic behavior. These last catalysts presented high glycerol conversions during the first hours of APR glycerol/water reaction, however, an important decrease in terms of glycerol conversion was observed after 24 h time-on-stream. The experimental results suggested that the most suitable stable and active catalyst was the NiPt/ASGI7 (better than >NiPt/ASGI6 > NiPt/ASGI5 >>> NiPt/ASGB7). This catalyst showed best catalytic activity and good catalytic stability along 56 h of time-on-stream, reaching, at steady state, highest total glycerol conversion (approximate to 79%) and glycerol into gaseous products (approximate to 57%) in APR reaction of glycerol/water mixture for hydrogen generation. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.