AVS 51st International Symposium
    Surface Science Friday Sessions
       Session SS2-FrM

Paper SS2-FrM9
Probing the Mechanism of n-hexane Dehydrocyclization over Pt-Sn Catalysts: Adsorption and Reactivity of n-hexane, 1-hexene, and 1,5-hexadiene on Pt(111) and Sn/Pt(111) Surface Alloys

Friday, November 19, 2004, 11:00 am, Room 210C

Session: Bimetallic Surface Chemistry and Structure
Presenter: H. Zhao, University of Southern California
Authors: H. Zhao, University of Southern California
B.E. Koel, University of Southern California
Correspondent: Click to Email
Supported bimetallic platinum catalysts are widely used to carry out skeletal reactions of alkanes, and such processes including dehydrocyclization are important for naphtha reforming. In order to clarify discussions of the mechanisms of these reactions, we have investigated the adsorption of n-hexane and the reactivity of several likely intermediates in such processes, i.e., 1-hexene and 1,5-hexadiene on well-defined, single-crystal surfaces of Pt(111) and two, ordered Sn/Pt(111) alloys under UHV conditions by using primarily TPD, AES, and LEED. Alloying caused a small decrease in the adsorption energy for all adsorbates. However, alloying decreased strongly the reactivity of 1-hexene and 1,5-hexadiene such that no dehydrogenation occurred during TPD on the (@sr@3*@sr@3)R30°-Sn/Pt(111) alloy with @THETA@@sub Sn@=0.33. This alloy surface does not contain pure-Pt 3-fold sites which can be inferred to be particularly reactive sites. Alloying did not decrease the saturation coverage of any of these molecules.