Controlled feeding can be achieved through various methods: 1. Flow Reactors: Use of continuous flow reactors where reactant flow rates are precisely controlled using pumps and valves. 2. Batch Reactors: In batch processes, reactants can be added in increments or at controlled rates using automated systems. 3. Pressure-Swing and Temperature-Swing Adsorption: These techniques allow for the periodic introduction of reactants to maintain constant reaction conditions.