Hydrogen production for fuel cell by oxidative reforming of diesel surrogate: Influence of ceria and/or lanthana over the activity of Pt/Al2O3 catalysts

A series of Pt catalysts supported on Al2O3 (Pt/A), Al2O3–CeO2 (Pt/A–C), Al2O3–La2O3 (Pt/A–L) and Al2O3–La2O3–CeO2 (Pt/A–L–C) have been prepared and tested in the oxidative reforming of diesel surrogate with the aim of studying the influence of ceria and lanthana additives over the activity and stability toward hydrogen production for fuel cell application. Several characterization techniques, such as adsorption–desorption of N2, X-ray diffraction, X-ray photoelectron spectroscopy, temperature programmed reduction, H2 chemisorption, and thermogravimetric analysis, have been used to define textural, structural, and surface properties of catalysts and to establish relationships with their behaviour in reaction. This physicochemical characterization has shown that lanthana inhibits the formation of α phase in alumina support and decreases ceria dispersion. Activity results show a better performance of ceria-loaded catalysts, being the Pt/A–C sample the system that offers higher H2 yields after 8 h of reaction. The greater H2 production for ceria-loaded catalysts, particularly in the case of the system Pt/A–C, is attributed to the Pt–Ce interaction that may change the electronic properties and/or the dispersion of active metal phase. Also, the CeIII form of CeIV/CeIII redox pair enhances the adsorption of oxygen and water molecules, thus increasing the catalytic activity and also decreasing coke deposition over surface active Pt phases. Stability tests showed that catalysts in which Pt crystallites are deposited on the alumina substrate covered by a lanthana monolayer, give rise to an increase in stability toward H2 production.