From Methane to Methanol: Pd-iC-CeO <sub>2</sub> Catalysts Engineered for High Selectivity via Mechanochemical Synthesis
Juan D. Jiménez, Pablo G. Lustemberg, Maila Danielis, Estefanía Fernández, Sooyeon Hwang, Iradwikanari Waluyo, Adrian Hunt, Dominik Wierzbicki, Jie Zhang, Long Qi, Alessandro Trovarelli, José A. Rodríguez, Sara Colussi, M. V. Ganduglia-Pirovano, Sanjaya D. Senanayake
Abstract
High Resolution Image Download MS PowerPoint Slide In the pursuit of selective conversion of methane directly to methanol in the liquid-phase, a common challenge is the concurrent formation of undesirable liquid oxygenates or combustion byproducts. However, we demonstrate that monometallic Pd-CeO 2 catalysts, modified by carbon, created by a simple mechanochemical synthesis method exhibit 100% selectivity toward methanol at 75 °C, using hydrogen peroxide as oxidizing agent. The solvent free synthesis yields a distinctive Pd-iC-CeO 2 interface, where interfacial carbon (iC) modulates metal-oxide interactions and facilitates tandem methane activation and peroxide decomposition, thus resulting in an exclusive methanol selectivity of 100% with a yield of 117 μmol/g cat at 75 °C. Notably, solvent interactions of H 2 O 2 (aq) were found to be critical for methanol selectivity through a density functional theory (DFT)-simulated Eley–Rideal-like mechanism. This mechanism uniquely enables the direct conversion of methane into methanol via a solid–liquid–gas process.