COLL 117 |
| To describe properties of nanosized Pd-based catalysts for methanol steam reforming (MSR) and dehydrogenation at an accurate DFT level, we applied periodic slab and three-dimensional nanocluster models. We focused on methoxide and formaldehyde as important intermediates of MSR and dehydrogenation. Dehydrogenation of formaldehyde was found to be more facile on Pd(111) than on PdZn(111), rendering MSR more favorable on PdZn, whereas Pd is a better dehydrogenation catalyst. With thermodynamic and kinetic modeling, we determined the composition of PdZn(111) under MSR conditions. We addressed the poisoning of Pd catalysts by carbonaceous species as byproducts of dehydrogenation, by exploring C-O bond scission of various intermediates of methanol dehydrogenation. CH3O and CH2OH were found to be likely candidates for C-O bond scission, but the activation barriers are still notably higher than for dehydrogenation. Finally, we showed that, in agreement with experiment, CHx species occupy preferentially positions at or near edges of the nanoparticles. |
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Surface Chemistry Symposium in Honor of Gabor Somorjai
8:30 AM-11:50 AM, Monday, 11 September 2006 Sir Francis Drake -- Franciscan Room, Oral
Division of Colloid & Surface Chemistry |