Ethanol decomposition and steam reforming of ethanol over CeZrO2 and Pt/CeZrO2 catalyst: Reaction mechanism and deactivation

The catalyst performance and the deactivation profiles of CeZrO2 and Pt/CeZrO2 were evaluated for the ethanol decomposition and steam reforming of ethanol reactions at 773 K. Unpromoted CeZrO2 was quite stable whereas Pt/CeZrO2 catalyst deactivated for all feed compositions studied. A reaction mechanism was proposed based on diffuse reflectance infrared spectroscopy analyses carried out under reaction conditions. The decomposition of the dehydrogenated and the acetate species is facilitated by the presence of the metal and resulted in high selectivity to hydrogen, methane, CO and CO2 over Pt/CeZrO2. Diffuse reflectance infrared spectroscopy, transmission electron microscopy and temperature programmed oxidation and desorption analyses indicate that the loss of the Pt-support synergy leads to a buildup of carbonaceous residue, which is the likely reason of the deactivation of Pt/CeZrO2. In addition, once the interfacial boundary is lost, the demethanation of acetate becomes hindered, resulting in an increase in acetaldehyde selectivity with time onstream.

DRIFTS spectra of Pt/CeZrO2 during the reaction shows an increase in the bands assigned to acetate species, which was accompanied by a decrease in the bands corresponding to adsorbed CO and CO2 formation. This suggests that the rate of acetate species decomposition decreased during the reaction, which probably led to their accumulation on the catalyst surface.Figure optionsDownload as PowerPoint slide