Metallic nanoparticles dispersed onto oxide supports have been used as catalysts for the synthesis of chemicals, pharmaceuticals and for energy applications. Mostly, conventional salt-impregnation methods were used for catalyst preparation, where the metal particles are formed in the presence of the support. In this case metal particle size, shape and dispersion of the catalytically active compound are influenced by a large number of parameters, e.g. the support and can therefore vary strongly.
In our group nanoparticles are synthesized continuously in microstructures. A colloid chemistry based method is used to synthesize differently sized metallic NP with narrow size distribution. The pre-formed metal nanoparticles are deposited onto the carrier material. During the last years microreaction technology has demonstrated its potential in formation of nanoparticles with well-defined properties like particle size, size distribution and composition. Due to the small size of the reactor channels mixing processes proceed very quickly and reaction conditions like temperature and residence time can be adjusted very exactly which allows to perform continuous nanoparticle formation with constant quality even in larger amounts. Because of their small hold up and the fast achievement of the steady state after a change of the operation conditions the influence of the reaction conditions on desired properties, e.g. particles size or size distribution can be studied and optimized in shorter time intervals than in a batch reactor. Microstructured devices are also used to get further insight in the formal processes leading to nanoparticle formation.