The use of modern catalysts requires the fabrication and knowledge of nanometre-sized particles whose catalytic efficiency depends upon not only their chemistry but also their topology both in terms of the particle size and shape and also their distributio n within the support. In Cambridge, there has been enormous advances in the synthesis and characterisation of heterogeneous catalysts consisting of bimetallic nanoparticles distributed within a silica mesoporous framework. The development of such catalyst systems depends critically on a knowledge of how the particles are distributed in three dimensions within the framework. Conventional electron microscopy whether in TEM or STEM mode will give only a projection of this structure and whilst this can give ext remely valuable information it does not reveal the full picture. Electron tomography has been developed to investigate (using only bright field images) the three-dimensional structure of viruses, macromolecules and so on. In this proposal, the aim is to us e the high angle annular dark field signal recorded under STEM illumination to investigate the 3-dimensional distribution of the nanoparticles. This kind of images are directly interpretably, are not plagued by phase contrast and be recorded quickly and ef ficiently in a modern analytical instrument. The installation of such a technique will be used to study a number of catalyst systems devoted mainly to nanoparticles of cobalt and of cobalt-iron and cobalt-gold on various light supports, such as mesoporous silica. The importance of cobalt as a powerful Fischer-Tropsch catalyst can hardly be over-emphasised. It is profoundly important if the cobalt co-exists (in a bimetallic entity) with either iron, or ruthenium (or with certain noble metals).The development of this project would allow the researcher to acquire a unique experience in catalysts characterization using a novel technique available in just a few laboratories in the world.
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