Site-Directed Synthesis of Cobalt Oxide Clusters in a Metal-Organic Framework.

Abstract

Direct control over structure and location of catalytic species deposited on amorphous supports represents a formidable challenge in heterogeneous catalysis. In contrast, a structurally well-defined, crystalline metal-organic framework (MOF) can be rationally designed using postsynthetic techniques to allow for desired structural or locational changes of deposited metal ions. Herein, naphthalene dicarboxylate linkers are incorporated in the MOF, NU-1000, to block the small cavities where few-atom clusters of cobalt oxide preferentially grow, inducing catalyst deposition toward hitherto ill-favored grafting sites orientated toward NU-1000s mesoporous channels. Despite the different cobalt oxide location, the resulting material is still an active propane oxidative dehydrogenation catalyst at low temperature, reaching a turnover frequency of 0.68 ± 0.05 h-1 at 230 °C and confirming the utility of MOFs as crystalline supports to guide rational design of catalysts.