Nature of oxide-supported copper(II) ions and copper derived from copper(II) chloride

Abstract

Cu2+ derived from aqueous CuC1, solutions and supported upon silica and anatase, but not alumina, shows asymmetric e.s.r. peaks and an absence of X.P.S. shake-up satellite peaks. Consideration is given to whether this may be attributed in part to its higher dispersion and different constrained symmetry. Divalent copper is stabilised by these oxide supports but in two different forms : one highly dispersed (with properties detectable by X.P.S. and e.s.r.) and the other poorly dispersed [as Cu,(OH),CI-type species on alumina and CuCl, on silica and anatase] characterisable by X.r.d. In respect to its effect upon the X.P.S. and reduction (but not e.s.r.) properties of supported Cu2+ species, rutile is different from anatase, a phenomenon which may be of some value in optimising activity of heterogeneous catalysts. The results cast doubt upon X.P.S. diagnosis of divalent copper. Resistivity measurements for titania-supported copper after reduction at 700 K suggest that very little of the copper may have been intercalated into the anatase support, but that on rutile such an intercalation may have been significant. This may be relevant to SMSI effects, especially at even higher reduction temperatures.

Effect of titania structure on the properties of its supported copper oxide catalysts

“…Cu + and Cu + ? Cu [38]. Giordano et al simulated the interaction between copper atoms and the (1 1 0) plane of rutile by the density function method.…”

Hierarchical PS/PANI nanostructure supported Cu(ii) complexes: facile synthesis and study of catalytic applications in aerobic oxidation

“…Shake-up satellite peaks were also observed at 942.3-944.8 eV, which belongs to the Cu 2+ species. 52 The Cu 2p XPS spectra also exhibits two additional peaks centered at 932.4 and 952.2 eV, which were attributable to the coordination between Cu 2+ species and amino groups. 53 The peak-tted N 1s core-line spectrums of three PS/PANI@ Cu(II) composites were shown in Fig.…”

The CuCl2/Al2O3 Catalyst Investigated in Interaction with Reagents

“…A further proof of the existence of two kinds of copper species arises from the study of the progressive evolution of the EPR signal (Figure 2b), as a function of the Cu loading. Even from a superficial investigation, it is evident that spectra of low loaded samples are typical of Cu(II) ions in axial symme-try (g xx = g yy ≡ g ⊥ and g zz ≡ g // ) [5][6][7][8][9][10]. For samples Cu0.25, Cu0.5 and Cu1.4, the splitting into quartets, due the hyperfine interaction between the unpaired electron and the copper nucleus (both 63 Cu and 65 Cu nuclei have a 3/2 nuclear spin [37]), is clearly visible only in the parallel component, while the perpendicular one exhibits only shoulders (samples Cu0.25, Cu0.5) or is completely unresolved (sample Cu1.4).…”

“…without additives) for the oxychlorination reaction only. Due to its relevant industrial impact, several papers have been devoted to its study [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. From these studies, the existence, on base catalyst, of two different Cu compounds is clearly emerging.…”