COLL 129 |
| Marc Schreier, Sara Teren, and J. R. Regalbuto. Dept. of Chemical Engineering, University of Illinois at Chicago, 810 S. Clinton, Chicago, IL 60607 |
| Many researchers have reported that "over-exchanged" or "excessively exchanged" Cu/ZSM-5 catalysts are those most active for NOx reduction. Since these preparative methods employ ammonium-containing solutions at high pH, it is plausible that adsorption could occur through the electrostatic interaction of cationic ammine complexes with a negatively charged surface. In this study we examine the nature of overexchanged Cu and Pt by measuring the uptake of these metals into zeolites with various Si/Al ratios as a function of pH, and comparing the uptake trends to that over pure silica. In short, when zeolites such as ZSM-5 contain little Al, electrostatic adsorption in the basic pH range occurs to a significant extent in addition to ion exchange. |
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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 |