Functionality

The functionality gains of microreactors are small thermal inertia, high gradients of physical properties, uniform temperature, short residence time, and high surface-volume ratio.

The small size of the system leads to small thermal inertia of reactors. Since temperature is one of the most important reaction parameters, direct and precise temperature control in microreactors is easier and faster than in conventional reactors. The small size also leads to higher heat and mass transfer rates, which allow carrying out reactions under more aggressive conditions than can be achieved in conventional reactors.

Furthermore, the high heat transfer rates allow reactions to be performed under more uniform temperature conditions [62]. The small size also results in shorter residence time in reactors. Instable intermediate products can be transferred quickly to the next process. These characteristics open up new reaction pathways inaccessible for conventional reactions.

According to scaling laws, microreactors offer a large surface-to-volume ratio, which leads to the effective suppression of homogeneous side reactions in heterogeneously catalyzed gas phase reactions. Large free surfaces are strong sinks for radical species, which are required for homogeneous reactions.

In addition, the reactions become safe because of the...