2
78
J.M. Fraile et al. / Journal of Catalysis 281 (2011) 273–278
Cu(II) species as recently shown for homogeneous C–O couplings
38]. This process would result in non-quantitative conversion of
Cu(II) to Cu(I) and then to lower activity of the Cu/SiO catalysts.
work to extent the applicability of these solids to other reactions in
the same family is in course.
[
2
Moreover, this series of reactions would induce Cu leaching from
the surface as no surface reorganization was deduced from the EX-
AFS of the after catalysis sample (Fig. 3). Analysis of the used cat-
alysts, after washing with methanol to remove organic residues,
Acknowledgments
This work was made possible by the financial support of the
Ministerio de Ciencia e Innovación (projects CTQ2008-05138 and
Consolider Ingenio CSD2006-0003), the European Commission
(IDECAT Network of Excellence), and the Diputación General de
Aragón (E11 Group co-financed by the European Regional Develop-
ment Funds).
2 2 3 2
shows very low copper loss for Cu4%SiO –Al O , whereas Cu8%SiO
losses about one-third of the total metal content (28%). In turn, the
lower Cu content may be the reason for its lower activity in the
second run.
2
The FFT EXAFS spectrum of the sample Cu8%SiO after catalysis
run (Fig. 3Aa) again shows two peaks corresponding to the Cu–O
and Cu–Cu neighbor shells of copper oxide phase. The sample
structure around copper sites is totally unchanged upon catalysis
reaction with respect to the fresh catalyst. The edge energy value
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