Chandler Catalysis Laboratory

Introduction

The controlled preparation of active sites on heterogeneous catalysts could improve several catalyst systems through the optimization of catalyst efficiency and increased reaction selectivity.  CTAB micelles have been used as surface templating molecules and provide for the encapsulation and deposition of aminopropyltriethoxysilane (APS) onto oxide supports, such as silica.  The number of active sites on each material was determined using spectroscopic measurements of cobalt(II) titrations and ninhydrin tests.  Further characterization of the active sites after micelle removal and surface alkylation with tetramethyldisilazane (TMDS) has been performed using fluorescence resonance energy transfer (FRET).  Indole-3-propionic acid, a fluorescence donor, and a variety of fluorescence acceptor molecules have been reacted with the surface amines on APS micelle-templated and APS grafted silica to provide a distribution of distances between the amines using the Förster radii of the specific donor and acceptor pairs.   These FRET studies will determine the extent of isolation of the active sites on oxide supports using the proposed templating scheme.  

Schemes and Figures

Micellar Templating Proposed Scheme.  Micellar deposition of alkoxyaminosilane groups on silica for the creation of isolated amine site.

Ninhydrin Reaction with Aminopropyltriethoxysilane (APS) Functionalized Silica