In situ ATR-IR studies in aqueous phase reforming of hydroxyacetone on Pt/ZrO2and Pt/AlO(OH) catalysts: The role of aldol condensation

Abstract

In situ Attenuated Total Reflection Infrared (ATR-IR) spectroscopy was used to study Aqueous Phase Reforming of hydroxyacetone on Pt/AlO(OH) and Pt/ZrO2catalysts at 230 °C/ 30 bar. Formation of strongly adsorbed aldol condensation products was observed on the surface of Pt/ZrO2and ZrO2in contrast to Pt/AlO(OH) and AlO(OH). Peak assignments were supported by DFT calculations of the IR spectra of the condensation products in vacuum and in the presence of water. Aldol condensation of hydroxyacetone leading to compounds with high molecular weight with unsaturated bonds was suggested as a first step in coke formation. Carbonaceous deposits on the surface of the ZrO2support are oxygen-rich and highly reactive, according elemental analysis and TPO. Surprisingly, no adsorbed CO on Pt was observed in the spectra obtained under reaction conditions, suggesting that adsorbed CO is not involved in the rate-determining step in APR of hydroxyacetone.