Hydrogen production by oxidative reforming of hexadecane over Ni and Pt catalysts supported on Ce/La-doped Al2O3

The activity and selectivity to hydrogen of alumina-supported nickel or platinum catalysts doped with Ce and La for the oxidative reforming of hexadecane were studied. The influence of both thermal stabilizer and activity promoter, such as lanthanum and cerium oxide, respectively, over hydrogen yield and catalyst durability was investigated. Catalytic activity was found to depend strongly on the type of metal, platinum showing lower specific activities per atom of metal exposed and a higher selectivity to combustion products than the Ni counterparts. The characterization results achieved with H2 chemisorption, XRD, TPR and XPS showed differences in surface metal concentrations and metal–support interactions which depend on the presence of cerium and/or lanthanum in the support composition. For both based metal catalysts higher reforming activities were found when active metals were deposited on Ce–La–Al2O3 substrate. For Pt-based catalysts, the increase in activity observed for the sample using Ce–La-modified alumina as support is suggested to be related with a participation of lanthanum in the reaction more than modifications on coke resistance or dispersion and state of platinum-induced by lanthanum. In the case of Ni-based catalysts, a lower carbon deposition and a higher thermal stability of metallic Ni particles under reaction conditions were observed for catalyst using Ce–La-modified alumina as support. It is suggested that the higher number of Ni–Ce and Ni–Al surface interactions developed Ce–La–Al2O3-supported Ni catalysts are responsible of the better catalytic behaviour of this sample in the oxidative reforming of hexadecane.