A catalytic reactor is a device used in chemical processes to accelerate reactions by using a catalyst. Catalysts are substances that increase the rate of a reaction without being consumed in the process. These reactors are commonly used in industries such as petroleum refining and chemical manufacturing to produce fuels, chemicals, and other products efficiently. In a catalytic reactor, reactants flow over a catalyst, which facilitates the conversion of these substances into desired products. The design of the reactor can vary, including fixed-bed, fluidized-bed, and packed-bed configurations, depending on the specific reaction and operational requirements.