Simultaneous Production of CH4 and H2 from Photocatalytic Reforming of Glucose Aqueous Solution on Sulfated Pd-TiO2 Catalysts

In this work, the simultaneous production of CH4 and H2 from photocatalytic reforming of glucose aqueous solution on Pd-TiO2 catalysts under UV light irradiation by Light-Emitting Diodes (LED) was investigated. The Pd-TiO2 catalysts were prepared by the photodeposition method. The Pd content was in the range 0.5-2 wt% and a photodeposition time in the range 15-120 min was used. Pd-TiO2 powders were extensively characterized by X-Ray Diffraction (XRD), SBET, X-Ray Fluorescence spectrometry (XRF), UV-Vis Diffuse Reflectance Spectra (UV-Vis DRS), TEM and X-Ray Photoelectron spectroscopy (XPS). It was found that the lower Pd loading (0.5 wt%) and 120 min of photodeposition time allowed us to obtain homogeneously distributed metal nanoparticles of small size; it was also observed that the increase in the metal loading and deposition time led to increasing the Pd0 species effectively deposited on the sulfated TiO2 surface. Particle size and the oxidation state of the palladium were the main factors influencing the photocatalytic activity and selectivity. The presence of palladium on the sulfated titania surface enhanced the H2 and CH4 production. In fact, on the catalyst with 0.5 wt% Pd loading and 120 min of photodeposition time, H2 production of about 26 μmol was obtained after 3 h of irradiation time, higher than that obtained with titania without Pd (about 8.5 μmol). The same result was obtained for the methane production. The initial pH of the solution strongly affected the selectivity of the system. In more acidic conditions, the production of H2 was enhanced, while the CH4 formation was higher under alkaline conditions. Dans cette recherche, la production simultanée de CH4 et H2 par le reformage photocatalytique de glucose sur les catalyseurs Pd-TiO2 sous irradiation de lumière UV réalisée par des diodes électroluminescentes (LED) a été étudiée. Les échantillons de Pd-TiO2 ont été préparés par la méthode de photodéposition. Le contenu de Pd était compris entre 0,5-2 % en poids et il a été utilisé un temps de photodéposition dans la gamme 15-20 minutes. Les poudres Pd-TiO2 ont été caractérisées par diffraction des rayons X (XRD), surface spécifique BET (SBET), fluorescence X (XRF), spectrométrie UV visible (UV vis DRS), microscopie électronique à transmission (TEM) et spectrométrie photo électronique X (XPS). Il a été constaté que le chargement inférieur de Pd (0,5 % en poids) et 120 minutes de temps de photodéposition conduit à une répartition homogène de