Autocatalysis through the Generation of Water during Methanol Oxidation over a Titania-Supported Platinum Catalyst
Nicholas S. Sapienza, Kristin N. Knight, Malik Albrahim, Md Raian Yousuf, Ayman M. Karim, John R. Morris
Abstract
Methanol may play a major role in a hydrogen economy by serving as one of the highest energy density compounds available; however, the precise reaction pathways for methanol oxidation catalysts have yet to be fully elucidated. Herein, a combination of packed-bed reactor studies and high-vacuum surface science techniques was used to elucidate the reaction mechanism of methanol oxidation over a Pt/TiO 2 catalyst. The reactor studies highlight that methyl formate is produced under mild reaction conditions, and full combustion to CO 2 is achieved at elevated catalyst temperatures. The surface science experiments show that the production of CO 2 proceeds through a surface-bound formate intermediate via multiple proton-coupled electron-transfer steps. Importantly, we also find that the water produced upon initial methanol adsorption plays a key role in unlocking the oxidative chemistry of this Pt-based material. These results provide valuable insight into potential modifications that could preferentially direct catalyst activity toward partial or full oxidation, thereby unlocking methods for producing valuable commodity chemicals.