CONCENTRATION FORCING IN AMMONIA SYNTHESIS: PLUG-FLOW EXPERIMENTS AT HIGH TEMPERATURE AND PRESSURE

Square-wave concentration forcing experiments have been performed for the ammonia synthesis reaction in an isothermal, fixed-bed, plug-flow reactor at a temperature and pressure approaching industrial conditions (703 K, 4.14Mpa). Using the optimal steady-state (OSS) production rate as a base for comparison, we have found that cycling between pure reactants (N₂, H₂) results in decreased time-averaged production rates as predicted by Wilson and Rinker (1982), while mixture cycling under appropriate conditions results in modest (but not insignificant) improvements over the OSS rate. We also have observed that the catalyst activity changes significantly under a variety of dynamic operating conditions.