Conversion of CO<sub>2</sub> to Methanol and Ethanol on Pt/CeO<i><sub>x</sub></i>/TiO<sub>2</sub>(110): Enabling Role of Water in C–C Bond Formation
Jesús Graciani, David C. Grinter, Pedro J. Ramírez, Robert M. Palomino, F. Xu, Iradwikanari Waluyo, Darı́o Stacchiola, Javier Fdez. Sanz, Sanjaya D. Senanayake, José A. Rodríguez
Abstract
The surface chemistry of alcohol synthesis from CO2 hydrogenation has been investigated using kinetic testing, ambient pressure X-ray photoelectron spectroscopy (AP-XPS), and DFT calculations over a multicomponent system, where Pt and ceria nanoparticles coexisted on a titania template, Pt/CeOx/TiO2(110). Due to its high ability to bind and activate CO2, not seen for typical Cu–ZnO catalysts, the Pt–CeOx–TiO2 interface is excellent for the hydrogenation of CO2 to methanol, with some ethanol also being produced (21% selectivity). The results of AP-XPS and DFT calculations indicate that the active state involves a mixture of Ti4+/Ti3+, Ce3+, and Pt0/Pt+. A fast pathway for the formation of CH3O species is only plausible when Ce3+ and Pt are present. The addition of water to the reaction feed facilitates the first hydrogenation of CO2 and substantially enhances the surface coverage of C-containing species (CH3O, HCOO, CO3, CHx), facilitating the formation of C–C bonds and the production of ethanol (38% selectivity).