Platinum/ceria/alumina catalysts on microstructures for carbon monoxide conversion

Platinum/ceria/alumina catalysts have been prepared by a sol-gel method and coated in the microchannels of stainless steel platelets. These catalysts are very active for the water-gas shift reaction between 300 and 400 °C. Moreover, they are non-pyrophoric and thus well suited for the purification of hydrogen for PEM fuel cells. The obtained coatings show good adherence and catalytic activity. The influence of the amount of platinum and ceria as well as the effect of a binder on the catalytic performance has been investigated. The samples have been characterized before reaction by XRD, SEM and by N2 adsorption measurements. The kinetics, free from internal diffusion limitations, over these thin films have been described by a power law rate equation. An activation energy of 86 kJ/mol has been found and at 260 °C the TOF corresponds to 0.6 ± 0.1 s-1 for all investigated samples. The superior activity of the platelets compared to the powder samples is attributed to the diffusion limitations inside the powder pellets. Thus catalysts deposited on microstructured platelets lead to a better platinum utilization