Interaction of ethoxy species with ceria surfaces: A combined IR and DFT perspective

S.H. HERNÁNDEZ GUIANCE; M. V. BOSCO; P. G. LUSTEMBERG ; A. BONIVARDI; J. VECCHIETTI; M. V. GANDUGLIA-PIROVANO

Santa Fe

Conferencia; VI San Luis Conference on Surfaces, Interfaces and Catalysis; 2018

Universidad Nacional del Litoral

The multiple physicochemical processes that characterize alcohols on surfaces are of great importance for a large number of applications related to the sustainable generation of clean energy. Hydrogen is a candidate to be established as the clean fuel of the future.1 Not being a primary energy source, because hydrogen is a vector that does not exist isolated in nature the use of H2 strongly encourages research to optimize and / or develop its production methods, which involve heterogeneous catalytic reactions. One of the most promising or convenient processes to produce a large amount of hydrogen is the ethanol steam reforming (ESR: CH3CH2OH + 3H2O → 2CO2 + 6H2) due to its 6:1 stoichiometric ratio, low toxicity and the fact that can be obtained from many sources ranging from classic sugars to cellulose biomass and algae.2 One of the challenges in the formulation of catalytic materials that are used in the ESR reaction lies in the development of active metal/oxide catalysts for which the formation of coke and the production of CO are inhibited. It has been reported that cerium dioxide (CeO2) may be suitable as a support of metal nanoparticles due to its high oxygen storage capacity, whereas at the same time oxygen mobility could improve the catalytic stability by preventing the sintering of metal particles and suppressing the formation of carbonaceous species.3 In this work, the nature of the ethoxy (CH3CH2O) species that are formed during its decomposition in the ESR reaction has been studied using a combination of infrared temperature-programmed surface reaction (TPSR-IR) on a ceria powder catalyst and nanocubes exposing the CeO2(100) surface with density functional theory (DFT) calculations. We interpret the TPSR-IR experiments by comparison with DFT results through the calculation of adsorption energies and the C-O stretching frequency of ethoxy species adsorbed on CeO2(111) and on two CeO2(100) reconstructed surfaces models as a function of the adsorption site and coverage.