Catalytic nanoliths

The nanoporous anodic aluminum oxide (AAO) structure is shown to be a useful platform for heterogeneous catalysis. By appropriately masking the perimeter during anodization and etching, the AAO can be formed at the center of an aluminum disc. The remaining aluminum ring connects seamlessly to the AAO and provides mechanical support for convenient handling. The supported AAO can be sealed in a standard fitting so that the nanopores in the structure function as an array of tubular reactors, i.e. a nanolith. Coating the walls with catalytically active materials turns the nanolith into a novel catalytic system. For the oxidative dehydrogenation (ODH) of cyclohexane, the nanolith catalytic system is superior to a conventional powdered catalyst in terms of both efficiency and in reducing over oxidation. A simple analysis of the flow through the nanolith combined with experimental data indicates that mass transfer through the nanopores follows a mixed flow model. (C) 2008 Elsevier Ltd. All rights reserved.