Reaction and Reactor Engineering

Abstract

Chemical engineering aims, on the one hand, at simulating and predicting phenomena with respect to chemical reactions, such as intrinsic reaction kinetics, mass transport, sorption effects, thermodynamic and hydrodynamic phenomena and, on the other hand, at the design, construction, and optimization of the corresponding reactors in which these reactions are performed. The present chapter starts with explaining how intrinsic reaction rates of chemical transformations occurring on a heterogeneous catalyst surface may be disguised by mass and heat transfer phenomena and how the occurrence of such limitations can be diagnosed. Subsequently, adsorption phenomena are described and it is explained how to account for them in a kinetic model. The third section of this chapter comprises a strategy to extrapolate gas phase kinetics towards liquid or three-phase reactions envisaging the up-scaling from ideal laboratory scale conditions to realistic commercial applications. Next, the focus moves from reaction towards reactor engineering. First, the traditional reactor types, i.e., batch, semi-batch, plug flow, and continuous stirred tank reactors, are discussed. Subsequently, microreactors, which are characterized by a much larger surface-to-volume ratio and, hence, exhibit an enhanced mass and heat transfer, are discussed. Finally, various methods of energy input are reported. Some specific reactor types such as monolith and membrane reactors, which are able to dramatically decrease the pressure drop, are discussed in more detail in the fifth section. The final section of this chapter aims at reactor and process design. It starts with a discussion on the hierarchical design strategy of chemical processes. Subsequently, reactor selection based on the specific boundaries of the indented application is addressed. The chapter wraps up with a discussion on the phenomena that should be accounted for while designing the selected reactor, i.e., capillary condensation, the catalyst wetting efficiency, the flow regime, and axial and radial dispersion.