Porous structure and particle size of silica and hydrotalcite catalyst precursors

Abstract

The subject of this thesis is the control of the porous structure of catalyst bodies. The first part deals with silica, that can be utilized as catalyst support with many industrially important catalytic reactions. The second part of the thesis deals with the preparation and characterization of solid catalysts having a tubular or a platelet microstructure. The success of zeolites in catalytic reactions is due to the fact that the shape of the porous structure can be controlled on an atomic scale. The possibility to adapt also the surface composition of zeolites has led to important catalytic possibilities. Besides zeolites other minerals have structures that are interesting for catalytic applications. Natural minerals usually are contaminated, which renders utilization for catalytic purposes difficult, in spite of the favourable price. As with zeolites synthetic minerals therefore have to be preferred. Synthetic chrysotile will be studied, mainly to calibrate the porometric technique. The preparation and characterization of layered structures will subsequently be dealt with. Structures of platelets the separation of which can be controlled by insertion of suitable charged clusters ("pillaring") are presenting interesting catalytic properties.