Lowering dimensions of double metal cyanide catalysts via nanophase synthesis

Double metal cyanides (DMC) are industrially used as heterogeneous catalysts for the synthesis of polymer intermediates. The reaction takes place on active sites on their outer surface. Maximizing the outer surface and reducing the bulk, inaccessible catalyst volume is therefore required to improve the catalyst activity. This implies that small catalyst particles or thin sheets should be formed. The current synthesis methods result in a rather heterogeneous catalyst morphology with a significant amount of bulk phase present. This research project will explore several synthesis strategies to acquire better control of the resulting catalyst size and shape. Using a support consisting of very thin sheets, the DMC catalyst phase will be forced to form a thin layer on top of it. Modifications of the support surface will be used to improve the connection between the support and the DMC particles. The support could be a material with a completely different composition than the DMC catalysts; it could also be a (structured) material, containing some of the elements that are required in the DMC synthesis. These elements can be used to transform the support surface itself into a DMC catalyst. To determine how thin or small the DMC phase can be before it loses its catalytic function, DMC catalysts with varying dimensions will be synthesized in a controlled manner, their performance will be monitored in catalytic test reactions and the local structure of the active site will be probed.