Shape-selective sieving layers on an oxide catalyst surface
Author: ["Christian P. Canlas","Junling Lu","Natalie A. Ray","Nicolas A. Grosso-Giordano","Sungsik Lee","Jeffrey W. Elam","Randall E. Winans","Richard P. Van Duyne","Peter C. Stair","Justin M. Notestein"]
Publication: Nature Chemistry
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Abstract
New porous materials such as zeolites, metal–organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al2O3 (thickness, 0.4–0.7 nm) with ‘nanocavities’ (<2 nm in diameter) on a TiO2 photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations. Templated atomic layer deposition (ALD) is used to create oxide ‘nanocavities’ on the surface of catalyst particles. Subnanometre-nm films containing nanocavities act as sieves for the underlying catalyst, resulting in high selectivities for the smaller of two reactants in competitive oxidations or reductions.
Cite this article
Canlas, C., Lu, J., Ray, N. et al. Shape-selective sieving layers on an oxide catalyst surface. Nature Chem 4, 1030–1036 (2012). https://doi.org/10.1038/nchem.1477
