The chemical transformation of CO2 into chemicals is a promising and interesting strategy to mitigate the increase of CO2 in the atmosphere. One valuable way is the production of syn-gas by the dry reforming of methane: Ni-based catalysts are highly active but also highly sensitive to carbon formation. Pure cerium oxide or as a component of mixed oxides as support of Ni was extensively investigated and showed promising results in limiting the deactivation by coking. This capability has been attributed to the specific properties of CeO2 to change oxidation state with the reversible redox transformation between Ce+4 and Ce+3. Accordingly, to defect chemistry the chemical reduction CeO2 leads to the release of lattice oxygen (OOx) from the bulk of the crystal, generating two oxygen vacancies (VO). During dry reforming, the oxygen vacancies over the CeO2-surface may adsorb the oxygen formed by the dissociation of CO2 on Ni sites, improving the reforming activity and the removal of carbonaceous deposits. However, the positive effect of CeO2 support on carbon removal has been reported to be particularly dependent on the catalyst preparation method which may affect Ni dispersion and metal support interaction. In the present work, the catalytic activity for the DRM reaction of nickel supported on ceria doped with different transition and rare-earth metals: samarium, lanthanum, zirconium and aluminium was investigated. The substitution of Ce+4 with aliovalent cations, such as La3+ and Sm3+, with different ionic radium involves the formation of defects and oxygen vacancies in the lattice, while Zr4+ produces a distortion that facilitates the Ce4+ reduction and increases the textural properties and surface area in reducing conditions, differently Al3+ does not form a solid solution with ceria. The metal doping affects also the strength of basic sites of ceria modifying the chemisorptions of carbon dioxide which is a reactant of DRM reaction. The purpose of this study is to enlighten, the role of oxygen vacancies of metal doped ceria support on the catalytic activity, selectivity, and stability of Ni-Me0.15Ce0.85O2-d catalysts.
Luisetto, I., Tuti, S., KOPULA KESAVAN, J., Romano, C., Iucci, G., Battocchio, C., et al. (2017). The role of oxygen vacancies in nickel supported on doped ceria for the dry reforming of methane. In CERAMICS FOR ENERGY (CEN 2017) - INTERNATIONAL FORUM ON CERAMICS AND INORGANIC MATERIALS.
The role of oxygen vacancies in nickel supported on doped ceria for the dry reforming of methane
LUISETTO, IGOR;TUTI, SIMONETTA;KOPULA KESAVAN, JAGADESH;ROMANO, Claudia;IUCCI, GIOVANNA;BATTOCCHIO, CHIARA;MENEGHINI, CARLO;
2017-01-01
Abstract
The chemical transformation of CO2 into chemicals is a promising and interesting strategy to mitigate the increase of CO2 in the atmosphere. One valuable way is the production of syn-gas by the dry reforming of methane: Ni-based catalysts are highly active but also highly sensitive to carbon formation. Pure cerium oxide or as a component of mixed oxides as support of Ni was extensively investigated and showed promising results in limiting the deactivation by coking. This capability has been attributed to the specific properties of CeO2 to change oxidation state with the reversible redox transformation between Ce+4 and Ce+3. Accordingly, to defect chemistry the chemical reduction CeO2 leads to the release of lattice oxygen (OOx) from the bulk of the crystal, generating two oxygen vacancies (VO). During dry reforming, the oxygen vacancies over the CeO2-surface may adsorb the oxygen formed by the dissociation of CO2 on Ni sites, improving the reforming activity and the removal of carbonaceous deposits. However, the positive effect of CeO2 support on carbon removal has been reported to be particularly dependent on the catalyst preparation method which may affect Ni dispersion and metal support interaction. In the present work, the catalytic activity for the DRM reaction of nickel supported on ceria doped with different transition and rare-earth metals: samarium, lanthanum, zirconium and aluminium was investigated. The substitution of Ce+4 with aliovalent cations, such as La3+ and Sm3+, with different ionic radium involves the formation of defects and oxygen vacancies in the lattice, while Zr4+ produces a distortion that facilitates the Ce4+ reduction and increases the textural properties and surface area in reducing conditions, differently Al3+ does not form a solid solution with ceria. The metal doping affects also the strength of basic sites of ceria modifying the chemisorptions of carbon dioxide which is a reactant of DRM reaction. The purpose of this study is to enlighten, the role of oxygen vacancies of metal doped ceria support on the catalytic activity, selectivity, and stability of Ni-Me0.15Ce0.85O2-d catalysts.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
