Chapter 10 - Mass Transfer and Catalytic Reactions

Abstract

In any catalytic system, not only should chemical reactions be considered, but also mass and heat transfer effects. For example, mass and heat transfer effects are present inside the solid porous catalyst particles, as well as in the surrounding fluid films. This chapter treats simultaneous reaction and diffusion in fluid films and in porous materials, as well as liquid-liquid diffusion and phase-transfer catalysis. Particular attention is given to the combination of chemical reactions and diffusion inside a catalyst particle. Isothermal and nonisothermal cases of reactions with different kinetics are discussed. Similar analysis is provided for immobilized enzymes with Michaelis-Menten kinetics. In addition to catalytic activity, selectivity can also be influenced by mass transfer phenomenon. A few very basic reaction types are analyzed. Impact of deactivation in the case of internal diffusion limitations is discussed. Examples of elucidation the influence of mass transfer by calculating the mass transfer coefficients and catalyst effectiveness factors are provided. Approaches applied to elucidate the impact of heat and mass transfer based on various experimental criteria are presented.