The application of precision engineering techniques to chemical reaction engineering has been identified as having numerous potential advantages for both the chemical process development and manufacture of chemicals. Most developed are the microfabricated components which perform the standard unit operations, i. e. micropumps, microvalves, micro heat exchanger and separation units. In comparison, the ongoing development of chemical microreactors acquires more effort for the availability of effective and reliable reactors, especially for heterogeneously catalyzed reactions. It is the purpose of this paper to briefly describe the intellectual and experimental ways of down scaling from industrially used multitube fixed bed reactor to microreactors including some illustrated applications. From the preceding information, we conclude that the extremely rapid heat and mass transport what is available through the engineered microstructures yielding reactors with high selectivities and even reaction rates. The development of microreactors for heterogeneously catalyzed reactions at present are focused on providing sufficient amounts of catalytic active material on the walls of the microstructures. This was identified as a crucial prerequisite for an extended variety of possible applications and assembling microchemical systems including the required unit operations as well as sensors, analyzers and electronic units for process managing and controlling. When the desired chemical microreactors and corresponding systems are available, they provide opportunities for point-of-use production of chemicals, for the time being in small, high purity amounts and also of inflammable or hazardous intermediates with storage and transportation restrictions.
