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Site-Dependent Activity of Atomic Ti Catalysts in Al-Based Hydrogen Storage Materials.

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Title: Site-Dependent Activity of Atomic Ti Catalysts in Al-Based Hydrogen Storage Materials.
Authors: Al-Mahboob, Abdullah1, Muller, Erik1, Karim, Altaf2, Muckerman, James T.2, Ciobanu, Cristian V.3, Sutter, Peter1 psutter@bnl.gov
Source: Journal of the American Chemical Society. 6/27/2012, Vol. 134 Issue 25, p10381-10384. 4p.
Subjects: Titanium catalyst activity, Hydrogen storage, Aluminum, Hydrogenation, Doping agents (Chemistry), Dissociation (Chemistry)
Abstract: Doping catalytically inactive materials with dispersed atoms of an active species is a promising route toward realizing ultradilute binary catalyst systems. Beyond catalysis, strategically placed metal atoms can accelerate a wide range of solid-state reactions, particularly in hydrogen storage processes. Here we analyze the role of atomic Ti catalysts in the hydrogenation of Al-based hydrogen storage materials. We show that Ti atoms near the Al surface activate gas-phase H2 a key step toward hydrogenation. By controlling the placement of Ti, we have found that the overall reaction, comprising H2 dissociation and H spillover onto the Al surface, is governed by a pronounced trade-off between lowering of the H2 dissociation barrier and trapping of the products near the active site, with a sharp maximum in the overall activity for Ti in the subsurface layer. Our findings demonstrate the importance of controlling the placement of the active species in optimizing the activity of dilute binary systems. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Doping catalytically inactive materials with dispersed atoms of an active species is a promising route toward realizing ultradilute binary catalyst systems. Beyond catalysis, strategically placed metal atoms can accelerate a wide range of solid-state reactions, particularly in hydrogen storage processes. Here we analyze the role of atomic Ti catalysts in the hydrogenation of Al-based hydrogen storage materials. We show that Ti atoms near the Al surface activate gas-phase H2 a key step toward hydrogenation. By controlling the placement of Ti, we have found that the overall reaction, comprising H2 dissociation and H spillover onto the Al surface, is governed by a pronounced trade-off between lowering of the H2 dissociation barrier and trapping of the products near the active site, with a sharp maximum in the overall activity for Ti in the subsurface layer. Our findings demonstrate the importance of controlling the placement of the active species in optimizing the activity of dilute binary systems. [ABSTRACT FROM AUTHOR]
ISSN:00027863
DOI:10.1021/ja304203y