Three-phase Catalytic Reactions G-L-S

In fine-chemicals production three-phase reaction systems are common for the hydrogenation and hydrogenolysis of different organic functional groups. Other reactions, such as heterogeneously catalyzed catalytic oxidations, hydrodesulfurizations, and reductive aminations are encountered less frequently. 

The three phases present in this kind of reaction are a gas phase, containing, 

Therefore, in the choice and design of three-phase reactors, not only must the intrinsic kinetics be considered, but also the mass-transfer characteristics. For example, it is useless to try and improve the reaction rate by using a more active catalyst or increasing the catalyst load, when the overall rate of reaction is determined by mass transfer from the gas bubbles to the liquid phase, i. e. when the latter is slow compared with the intrinsie rate of reaction. Instead, one should 

Heat-transfer limitations can also occur, because many catalyzed gas-liquid reactions are exothermic. This might lead to the formation of local hot spots. This occurs readily for oxidation and hydrogenation reactions in particular. 

---