Spray deposition method for the synthesis of supported catalysts with superior metal dispersion

We introduce a novel 'spray deposition' method as a continuous, reproducible, versatile, simple, and scalable method for the preparation of highly-dispersed, uniformly-sized, and sintering-resistant supported metal nanoparticles on porous supports. Instant drying of aqueous aerosol droplets containing the metal precursor (e.g. palladium nitrate) and the support (e.g. ferrierite zeolite) in a commercial bench-scale spray drier proves the key for maximizing the metal dispersion. In contrast, the much lower rates of solvent removal characteristic of dry and wet impregnation methods using classical drying or even freeze drying led to broad particle size distributions. The spray-dried Pd/ferrierite catalyst exhibited high alkene selectivity in the gas-phase hydrogenation of propyne. These results demonstrate that spray drying is not only a highly suited unit operation to prepare catalyst supports but also functional catalysts in one step. The method offers attractive opportunities for large-scale catalyst manufacture and as well as for preparation of well-defined systems for academic studies. (C) 2011 Elsevier Inc. All rights reserved.