Chromium and lanthanum on transition alumina surfaces: The role of bulk point-defect distributions on catalytic activity

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Title: Chromium and lanthanum on transition alumina surfaces: The role of bulk point-defect distributions on catalytic activity
Author(s): Rashkeev, Sergey N.; Sohlberg, Karl; Glazoff, M. V.; Novak, J.; Pennycook, Stephen J.; Pantelides, Sokrates T.
Date: 2003
Abstract: We employ a combination of Z-contrast scanning transmission electron microscopy (ZSTEM) and first-principles density-functional calculations to investigate the interaction between metal atoms and cubic alumina catalytic supports. We show that there are two observed La sites at the porous γ- alumina surface, and that single La atoms do not exhibit a tendency to cluster. Cr behaves very differently from La - it has a tendency to cover the alumina surface in ordered, periodic raft-like patches. The degradation of the chromia/alumina catalyst is related to the possibility for the chromium to move away from the surface into the bulk, and the activation barrier for such a process is higher in η- alumina than in γ- alumina, i.e., η- alumina is a more durable support for chromium catalyst.
Citation: 2002 Fall Proceedings, 751, p. Z2.7.1 - Z2.7.6.
URI: http://hdl.handle.net/1860/1812
In Collections: Drexel Research

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