Synthesis of supported catalysts by impregnation and drying using aqueous chelated metal complexes

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.