COLL 128 |
| J. R. Regalbuto1, Marc Schreier1, Jianming Liu1, Jeffrey T. Miller2, and Arthur J Kropf3. (1) Dept. of Chemical Engineering, University of Illinois at Chicago, 810 S. Clinton, Chicago, IL 60607, (2) E-1F, BP Research Center, 1510 W. Warrenville Road, Naperville, IL 60563, (3) Argonne National Laboratory, Chemical Technology Division, 9700 S. Cass Avenue, Argonne, IL 60439 |
| The Revised Physical Adsorption (RPA) model can predict, to a reasonable degree, the adsorption of the aqueous phase metal complexes arising from chloroplatinic acid (CPA) onto alumina as occurs during catalyst impregnation. In the present work, the extension of the RPA model to other noble metals and to other oxide supports is investigated. To survey a number of oxide supports, chloroplatinic acid (CPA or [PtCl6]-2) and platinum tetraammine (PTA or [(NH3)4Pt]+2) adsorption was measured below and above the respective PZCs of various silica, titantia, ceria, and zirconia supports. Adsorption of the anionic chlorides [PtCl6]-2, [PtCl4]-2, [PdCl4]-2, and [AuCl4]-1, and [RhCl6]-3 was compared over gamma-alumina in the acidic pH range. The adsorption of CPA and PTA on the various oxides appears to be chiefly electrostatic in nature. The behavior of the non-Pt(IV) chlorides over alumina at low pH is more complex, however. Deviation from an electrostatic mechanism may be explained by 1) the metal complexes are not neat, unhydrolyzed anions, or 2) the adsorption mechanism is not strictly electrostatic but may involve surface grafting. EXAFS and XANES analysis of dissolved and adsorbed complexes will be brought to bear on these issues. |
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The Science and Engineering of Catalyst Preparation
8:30 AM-11:55 AM, Monday, March 29, 2004 Marriott -- Orange County 3, Oral
Division of Colloid and Surface Chemistry |