IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Applied Surface Analysis Friday Sessions
       Session AS-FrM

Paper AS-FrM4
XPS Analysis of Silica Supported Copper Catalysts for Fine Chemicals Synthesis

Friday, November 2, 2001, 9:20 am, Room 134

Session: Catalysis and Surface Reactivity
Presenter: S.J. Hutton, Kratos Analytical, UK
Authors: K. Wilson, University of York, UK
A. Stewie, University of York, UK
S.J. Hutton, Kratos Analytical, UK
A.J. Roberts, Kratos Analytical, UK
Correspondent: Click to Email
Tightening legislation has led to a drive to develop new cleaner heterogeneously catalysed processes for the speciality chemicals industries.@footnote 1,2,3@ One major area of concern is the wide range of organic synthetic routes that currently rely on the use of inorganic or mineral acids. In recent years, metal trifluoromethanesulfonates or triflates have been reported as a new and interesting type of Lewis acid.@footnote 4@ These possess stronger Lewis acidity and higher water tolerances than their halide counterparts, which readily form the hydroxide or oxide.@footnote 5,6@ Recently we have discovered that silica supported Cu(SO@sub 2@CF@sub 3@)@sub n@ is an effective heterogeneous catalyst for the use in organic synthesis. We find that while silica supported catalysts exhibit high activity in phenol alkylation, versions supported on alumina or amine functionalised silica are relatively inactive. The origin of the high activity of Cu(SO@sub 2@CF@sub 3@)@sub 2@/SiO@sub 2@ has been investigated by high resolution XPS analysis of a range of supported and unsupported Cu(II) and Cu(I) salts to determine the oxidation state of the active Cu species. The copper 2p spectrum of free Cu(SO@sub 2@CF@sub 3@)@sub 2@ exhibits a main peak at 936.6 eV which has associated strong satellite transitions. In contrast, silica supported Cu(SO@sub 2@CF@sub 3@)@sub 2@ exhibits a single transition at 933.8 eV without the presence of intense satellite structures. This suggests that electron transfer from SiO@sub 2@ could be important in determining catalytic activity. @FootnoteText@ @footnote 1@ J.H. Clark, D.J. Macquarrie, Chem. Comm., 1998, 853. @footnote 2@ R. Sheldon, Chem. Ind., 1, 1997, 12. @footnote 3@ W.F. Hölderich, Stud. Surf. Sci. & Catal. 1993, 75, 127. @footnote 4@ S. Kobayashi, Chem. Lett., 1991, 2187. @footnote 5@ S. Kobayashi, Synlett, 1994, 689. @footnote 6@ K. Wilson, A. Renson, J.H. Clark, Cat. Lett., 1999, 61, 51.