Multiphase catalytic reactor engineering and design for pharmaceuticals and fine chemicals

Abstract

A review of recent developments in multiphase catalytic processes for the manufacture of pharmaceutical and fine chemicals, and an overview of reaction engineering principles needed for analysis of the local and overall reaction rate for reactor design and interpretation of performance is presented. The first section gives an overview of recent applications in pharmaceuticals and fine chemicals where heterogeneous and homogeneous catalyzed multiphase chemistries have been identified that are more efficient and represent safer operation with decreased environmental impact when compared to existing processes. The next three sections describe a scheme for classification of the various types of reactions that are typically encountered, along with distinguishing features of these reactions and commonly used multiphase reactor types. This is followed by a review of reaction engineering principles needed for describing the local overall rate of reaction, including a summary of typical models for evaluation of the intrinsic reaction kinetics, incorporation of transport-kinetic interactions, methods for identification of the controlling reaction regime and assessment of the relative contribution of transport effects. The next two sections set forth basic reactor models for commonly used reactor types, including mechanically agitated reactors and bubble column reactors. A brief summary of commonly used correlations for estimation of mass transfer coefficients in these reactors for gas-liquid and liquid-liquid systems is also given. The final section is devoted to a summary of key reaction engineering issues that occur in pharmaceutical and fine chemical multiphase catalytic processes, along with some thoughts on future needs and challenges.