A fixed-bed reactor is a special form of reactor in which one or more fluids flow through a solid bed or packing. The fixed bed is often used to fix heterogeneous catalysts or – in bioreactors – microorganisms.
Fixed-bed reactors are the most commonly used type of reactor in the chemical and petrochemical industries. Fixed-bed reactors are also used for mobile and stationary waste gas purification. All fixed-bed reactors have in common that a solid material, usually a catalyst, is spatially fixed in the reactor and is flowed through or over by the reaction mixture.