We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Copper Complexes Stabilized by Chitosans: Peculiarities of the Structure, Redox, and Catalytic Properties.
- Authors
Kramareva, N. V.; Finashina, E. D.; Kucherov, A. V.; Kustov, L. M.
- Abstract
Peculiarities of the structure and physicochemical properties of copper–chitosan complexes prepared by different methods were studied by IR, UV-visible, ESR spectroscopy, and electron microscopy. The catalytic activity of redox copper centers stabilized by the chitosan matrix in the reactions of oxidation of o- and p-dihydroxybenzenes in an aqueous medium was determined. Quantitative ESR measurements provide evidence for the localization of virtually all copper ions introduced in the initial heterogeneous chitosan samples with copper contents below 1.5 wt % in the form of isolated Cu2+ ions in square planar coordination. The chitosan matrix was shown to strongly bind copper ions under conditions of redox transformations in the catalytic tests or upon prolonged heating in boiling water. Reoxidation of the samples with H2O2 results in quantitative restoration of the initial ESR signal of Cu(II). Heterogenized copper–chitosan samples exhibited high activity and stability in the catalytic oxidation of dihydroxybenzenes into quinones, whereas the homogeneous system was characterized by irreversible poisoning due to formation of copper–hydroquinone complexes. Preparation of the binary composite system with a thin heterogeneous copper–chitosan film supported on a macroporous silica allows one to dramatically enhance the specific catalytic activity and the efficiency of the active component. Such an approach may turn out to be useful in the synthesis of supported chitosan catalyst with a low noble metal content.
- Subjects
CHITOSAN; SPECTRUM analysis; ELECTRON microscopy; COPPER; OXIDATION; SILICA
- Publication
Kinetics & Catalysis, 2003, Vol 44, Issue 6, p793
- ISSN
0023-1584
- Publication type
Article
- DOI
10.1023/B:KICA.0000009056.74699.b8