Supported catalysts which contain a platinum metal and a process for preparing diaryl carbonates

Process for preparing an organic carbonate by reacting an aromatic hydroxy compound with carbon monoxide and oxygen in the presence of supported catalysts containing (i) an oxide of the elements silicon, aluminium, titanium, zirconium or a mixture of oxides of these elements, (ii) one or more co-catalytic metals oxides from groups 4, 5, 6, 7, 11, 12, 13, 14, the iron group (atomic numbers 26 to 28) or the rare-earth metals (atomic numbers 58 to 71), and (iii) one or more platinum metals or one or more compounds of platinum metals (atomic numbers 44 to 46 and 77 and 78) in an amount 0.01 to 15 wt.%, calculated as platinum metals and with respect to the total weight of catalyst, which are obtained by preparing a gel from one or more suitable precursor(s) of the components mentioned under (i) and (ii), ageing, drying and optionally annealing the gel, shaping the mixed metal oxide obtained in this way and then applying the platinum metal component (iii) to the mixed metal oxide.