METHOD OF PREPARING A CATALYST STRUCTURE

The present invention relates to a method of preparing a catalyst structure comprising a metallic catalyst and a metal oxide the method comprising the steps of: providing a solution of a metal oxide precursor; providing an aqueous reactive solvent in a supercritical or subcritical state; mixing the solution of the metal oxideprecurs or with the supercritical or subcritical aqueous reactive solvent to form an aqueous reactant mixture; injecting the aqueous reactant mixture into a reactor tube via a first inlet; re-establishing supercritical or subcritical conditions in the reactor tube if necessary; allowing a hydrothermal reaction of the metal oxide precursor in the supercritical or subcritical aqueous reactant mixture in the reactor tube to form metal oxide nanoparticles; providing at ambient conditions a solution of a metal precursor in a solvent; injecting the solution of the metal precursor into the reactor tube via a second inlet downstream of the first inlet; re-establishing supercritical or subcritical conditions in the reactor tube if necessary; allowing a reduction reaction of the metal precursor in the supercritical or subcritical reactant mixture to form metallic nanoparticles on the metal oxide nanoparticles; withdrawing the catalyst structure from the reactor tube via an outlet. The catalytic structuremay be an exhaust catalyst and is suitable for use in diesel oxidation catalysis or three way catalysis.