Isao Ogino

Genesis of Delaminated-Zeolite Morphology: 3-D Characterization of Changes by STEM Tomography

Zeolite delamination increases the external surface area available for catalyzing the conversion of bulky molecules, but a fundamental understanding of the delamination process remains unknown. Here we report morphological changes accompanying delamination on the length scale of individual zeolite clusters determined by 3-D imaging in scanning transmission electron microscopy. The results are tomograms that demonstrate delamination as it proceeds on the nanoscale through two distinct key steps: a chemical treatment that leads to a swelled material and a subsequent calcination that leads to curling and peeling off of delaminated zeolite sheets over hundreds of nanometers. These results characterize the direct, local, 3-D morphological changes accompanying delaminated materials synthesis and, with corroboration by mercury porosimetry, provide unique insight into the morphology of these materials, which is difficult to obtain with any other technique.

Chapter 2:Zeolite-supported Molecular Metal Complex Catalysts

Structural non-uniformity and complexity of supported metal catalysts used in industry hamper precise determination of the structure of active sites as well as their structure–performance relationships. When metals are atomically dispersed on a high surface area support, non-uniformity of a support causes non-uniformity of the structure of supported metals, leading to diverse catalytic properties. This chapter describes the synthesis, characterization and catalysis of zeolite-supported molecular metal complex catalysts with a high degree of uniformity. Zeolite-supported molecular metal complex catalysts described here is a sub-class of supported metal catalysts and have mono-nuclear transition metal complexes anchored in zeolites. Because zeolites are crystalline and have nearly uniform anchoring sites for metal complexes, they provide the opportunity to synthesize structurally uniform supported metal species. Proper choices of metal complex precursors, zeolites, and a synthesis method are required to form high uniformity of supported species. Such highly uniform supported metal complexes allow one to conduct exact structural determination by spectroscopic characterization, leading to elucidation of their molecular chemistry at an unprecedented level. Deep understanding of molecular chemistry of zeolite-supported metal complex catalysts will shed significant insights into complex chemistry that takes place on industrial catalysts and lead to synthesis of new selective catalysts.