resumo
Density functional theory (DFT) calculations were employed to study the dissociation of the O-H bond in methanol on several planar and stepped bimetallic transition metal surfaces, composed of elements showing high or moderate activity towards this reaction, namely, Ni, Rh, Ru, Ir, Pd, Au, Zn and Cu. The activation energies for the O-H bond cleavage were compared with those estimated using a Bronsted-Evans-Polanyi (BEP) relationship for the RO-H bond breakage on pure metal transition surfaces, relating the activation energy for the reaction with the adsorption energies of the reaction products, RO center dot and H-center dot adsorbed on the surface of the catalyst. Furthermore, the average differences between the values of the activation energies calculated with the exhaustive determination of the full reaction path and location of the transition state on each surface model and the activation energies obtained from the BEP relationship with the simple calculation of the adsorption energies of the RO center dot and H-center dot species are similar to 0.14 eV. This suggests that the BEP relationship developed upon the consideration of data for dissociation of the O-H bond in alcohols and water on pure metal surfaces is also valid for a qualitative prediction of the methanol activation energy on bimetallic surfaces.
palavras-chave
TOTAL-ENERGY CALCULATIONS; WAVE BASIS-SET; HYDROGEN GENERATION; PARTIAL OXIDATION; CATALYSTS; ETHANOL; DECOMPOSITION; DESCRIPTORS; MOLECULES; PLATINUM
categoria
Chemistry
autores
Fajin, JLC; Cordeiro, MNDS; Gomes, JRB
nossos autores
José R. B. Gomes
Investigador Principalagradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement and also within the scope of the project UID/QUI/50006/2013 attributed to LAQV@REQUIMTE. JLCF and JRBG acknowledge FCT for the grant SFRH/BPD/64566/2009 co-financed by the Programa Operacional Potencial Humano (POPH)/Fundo Social Europeu (FSE)/Quadro de Referencia Estrategico Nacional 2009-2013 do Governo da Republica Portuguesa and for the Programme Investigador FCT, respectively.