Reaction Rate Control: Proper metering ensures that the reactants are supplied at a rate that matches the catalyst's capacity to convert them into products. Selectivity: By controlling the flow rates, the metering zone helps in achieving the desired selectivity of the catalytic process. Yield Optimization: Accurate metering can lead to higher yields by minimizing the formation of by-products. Thermal Management: Controlling the flow rates helps in managing the heat generated or consumed during the reaction, thereby maintaining a stable reaction temperature.