THE ENVIRONMENT AND THE CHALLENGES TO REACTION-ENGINEERING

Ultra-high conversions required in ''ppm reactions'' may result in a b reakdown of the simple Langmuir approach for formulating reaction kine tics. Micro-kinetic analysis may provide a consistent basis for kineti c expressions covering a wide range of gas compositions. The impact of mass transfer restrictions changes in a complex way as concentrations approach zero, but the analysis of first-order reactions remains simp le, Better knowledge of fluid mechanics is important in controlling ma ldistribution of flows and mixing of reactants. These aspects are illu strated by examples including selective catalytic reduction of NOx, ca talytic oxidation, and methanation in ammonia plants.