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Work is reviewed on the synthesis of supported metal and metal oxide catalysts using impregnation of an aqueous solution of chelated metal ions followed by drying. The nature of the aqueous solutions of chelated complexes is discussed first. Upon solvent evaporation a steep increase in viscosity is apparent, which inhibits redistribution of impregnated solution upon drying of the support bodies. Furthermore, a gel-like phase is formed that favors high dispersions of the active phase after full drying. Second, several examples are dealt with in some detail, in particular supported iron, nickel, and cobalt-molybdenum catalysts. Finally an overview is presented for metal and metal oxide precursors that can be suitably deposited upon support materials using chelated aqueous metal complex solutions.

Magnesium dihydride contains 7.7 wt % hydrogen. However, its application for hydrogen storage is impeded by its high stability and slow kinetics. Bringing the size of Mg(H 2 ) into the nanometer range will not only enhance the reaction rates but has also been theoretically predicted to change the thermodynamic stability and destabilize the MgH 2 with respect to Mg. However, the preparation of such small particles is a major challenge. We identified a method to prepare large amounts of nanometersized nonoxidized magnesium crystallites. The method is based on infiltration of nanoporous carbon with molten magnesium. The size of the Mg crystallites is directly influenced by the pore size of the carbon and can be varied from 2-5 to less than 2 nm. The majority of the nanocrystallites is not oxidized after preparation. No bulk magnesium was detected in the samples with nanoparticle loadings up to 15 wt % on carbon. These 3D supported nanomaterials present interesting systems to study how nanosizing and support interaction can steer the hydrogen sorption properties of metal hydrides.