Bimetallic Cu-Pt Catalysts over Nanoshaped Ceria for Hydrogen Production Via Methanol Decomposition

A series of Pt/CeO2 (5 wt%) and bimetallic Cu-Pt/CeO2 (4 wt% Cu and 1 wt%) catalysts supported on different CeO2 nano shapes (polyhedra, rods, and cubes) were studied as catalytic systems for hydrogen production from the methanol decomposition (MD) reaction. Supports were prepared by hydrothermal approach and the active phase was incorporated by wet impregnation. Materials were characterized by SEM, HRTEM-STEM, N-2 adsorption, EDS, XRD, Raman spectroscopy, H-2-TPR, and CO-DRIFTS. The catalytic properties for MD reaction were studied as a function of temperature in the 100-450 degrees C range and as a function of time on-stream for 24 h at 350 degrees C. Despite the high methanol conversion presented by the Pt/CeO2 catalysts, more important in polyhedra and rods, these catalysts exhibited a low hydrogen yield. Differences in the properties of bimetallic Cu-Pt/CeO2 samples were established to be support-morphology-dependent, and the dispersion of copper and the ceria reducibility were superior in samples supported on polyhedra and rods as in the case of platinum catalysts. An improvement of the oxygen vacancies in the bimetallic system was also observed, as a result of the close interaction between copper and ceria. TOF values indicated that catalytic performances are promoted not only by the size of the active phase nanoparticles, but also by the facet predominantly exposed by ceria. The formation of bimetallic phase and the presence of surface Cu-Pt alloy sites in the rod-shaped sample accounted for the slightly better methanol conversion in the stability tests. The H-2 yield in the bimetallic samples was superior compared to platinum, which makes them suitable candidates for the hydrogen production from the methanol decomposition.