Evidence for different copper species in precursors of copper–cerium oxide catalysts for hydrogenation reactions. An X-ray diffraction, EPR and X-ray photoelectron spectroscopy study

Abstract

Conditions for preparing copper-cerium mixed oxides by coprecipitation have been examined. X-Ray diffraction (XRD), electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the oxides calcined at different temperatures up to 1073 IS. In all cases, a solid solution is formed by the insertion of Cu2+ ions in substitutional Paper 5/04920B;

Hydrogen Production by Ethanol Steam Reforming (ESR) over CeO2 Supported Transition Metal (Fe, Co, Ni, Cu) Catalysts: Insight into the Structure-Activity Relationship

“…The spectrum of the Cu/CeO 2 sample is characterized by a Cu 2p 3/2 band at 933.8 eV and shake-up satellites at ca. 944.0 eV, typical characteristics of Cu 2+ species in CuO-like phase [20,48,[66][67][68][69][70]. The above assignments are in line with the XRD findings, which revealed the formation of the corresponding metal oxides in M/CeO 2 samples (Table 2).…”

Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 January--31 March 1996

“…In the case of Rh2+, Anderson and co-workers [31] have reported that rhodium ions on ceria surface were stabilized against reduction and aggregation by incorporation of the Rh cations to cerium oxide surface layers, resulting in a high metal dispersion. The same phenomenon has been observed with Cu2' ions on ceria surface [2,32]. Lamonier et al [2] have demonstrated that the insertion of Cu2' into the ceria lattice occurred during the coprecipitation step of catalyst preparation, resulting the creation of anionic vacancies upon calcination.…”

“…The same phenomenon has been observed with Cu2' ions on ceria surface [2,32]. Lamonier et al [2] have demonstrated that the insertion of Cu2' into the ceria lattice occurred during the coprecipitation step of catalyst preparation, resulting the creation of anionic vacancies upon calcination. Four different copper species attributed to monomers, dimers, clusters and small particles of CuO have been found.…”

“…The CuO phase was not detected, suggesting that copper oxide was well dispersed or formed a solid solution upon Cu2' insertion into the ceria lattice [2]. Lamonier et al [2] have found that for a wide range of ceridcopper compositions, a solid solution is always formed by insertion of Cu2" ions in substitutional positions in the ceria lattice. This process occurs at the coprecipitation step and is maintained during calcination.…”

Catalisadores de cobre suportados sobre óxidos mistos CeO2TiO2 preparados pelo método sol-gel: caracterizações físico-químicas e teste catalítico - conversão do metanol

“…Para tanto se deve considerar a não influência da temperatura de calcinação do catalisador na quantidade de cobre superficial na segunda razão e a grande variação de cobre exposto na primeira. Além do mais, Lamonier et alo [58] estudando catalisadores do tipo Ce-Cu-O por XPS também constatou a migração do cobre contido no "bulk" da céria com o aumento da temperatura de calcinação. * Diminuição da razão superficial com relação à razão nominal .…”