High-temperature catalysts through sol-gel synthesis

Sol-gel chemistry is an efficient tool for controlling morphology and reactivity of solids and its potential in the development of tailor-made and thermally stable industrial catalysts is discussed. The key targets in catalyst preparation are mechanically and thermally stable morphology, highly dispersed active phase on homogeneous carrier and porosity minimising diffusional limitation. Sol-gel chemistry approach to the development of such catalysts is illustrated through examples. By controlling gelation and drying steps, 'aerogel-like' morphologies with good mechanical properties in which the reactants molecules have an open access to the active sites, practically without mass transfer limitation are obtained under non-hypercritical conditions. Highly dispersed supported metallic catalysts as well as homogeneous mixed oxides carriers have been prepared which remain very stable at high temperature. This opens the way to prepare high-performance industrial catalysts which could not be prepared without the sol-gel approach. (C) 1998 Elsevier Science B.V. All rights reserved.