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submitted on 08.05.2020 and posted on 11.05.2020by Julia Vecchietti, Pablo Lustemberg, Esteban L. Fornero, Monica Calatayud, Sebastián E. Collins, Susanne Mohr, M. V. Ganduglia-Pirovano, Joerg Libuda, Adrian L. Bonivardi
The ethanol steam reforming reaction, together with the adsorption and decomposition of ethanol was studied on CeO2 and gallium-doped ceria (CeGaOx) by a combined experimental and theoretical approach using infrared spectroscopy (IR), mass spectrometry (MS) and density functional theory (DFT) calculations. At 100°C, different types of monodentate ethoxy species were identified as standing-up (SU) on Ce4+ and lying-down (LD) on Ce4+ and Ga3+, with the alkyl chain more perpendicular or parallel to the surface, respectively. It is suggested that the incorporation of Ga into the ceria lattice changes the decomposition pathway of LD species, which converts to acetate instead of ethylene, attributed to the increased lattice oxygen lability in the Ce-O-Ga interface upon doping and the propensity to form Ga-H surface species. Under ethanol steam reforming conditions, Ga doping of ceria-based materials has a drastic effect by improving the H2:CO2 ratio, changing the product distribution and reducing coke formation.
This work has been financed with the ANPCyT (PICT 2015-3651 and PICT-2016-2750) and UNL-CAID (PI 50420150100066LI) projects. S.M. and J.L. acknowledge support by the Deutsche Forschungsgemeinschaft (DFG, project number 214951840) and within the Excellence Cluster ‘Engineering of Advanced Materials’. This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 832121. M.V.G.-P. acknowledges the financial support of the Ministry of Economy and Competitiveness MINECO-Spain (grant Nr. CTQ2015-78823-R) and of the Ministry of Science, Innovation and Universities MICINN-Spain (grant Nr. RTI2018-101604-B-I00). Computer time provided by the RES resources at Marenostrum and LaPalma nodes, the IFIR and CONICET at the Piluso and Tupac nodes, respectively. We acknowledge PRACE for awarding us access to Finisterrae (CESGA), Spain. The GENCI- CINES/IDRIS (Grants 2018- x2018082131 2019- x2019082131) and the CCRE-DSI of Sorbone Université, are thankfully acknowledged.