Monoliths as multiphase reactors: A review

Monolith reactors are being studied as a replacement for conventional multiphase reactors such as trickle‐bed reactors, slurry reactors, and slurry bubble column reactors for gas–liquid–solid reactions. Reactors with monolith catalyst packing have been found to be hydrodynamically superior to existing industrial reactors. This review covers multiphase reactions carried out in monolith reactors by various researchers. It first defines the monolith reactor and looks into the geometrical aspects of monolith. The section dealing with hydrodynamics reviews pressure drop, phase holdup, flow distribution, and dispersion characteristics. This study also considers the tools used to characterize the hydrodynamic parameters and their typical values. Although the available literature is scarce, monoliths are considered to have superior mass transfer characteristics. This review lists the mass transfer correlations for each category (gas–liquid, gas–solid, liquid–solid). The last section discusses the reaction aspects of monolith reactors. The ultimate goal is to implement such reactors for multiphase reactions. This section also compares the performance of monolith reactors with conventional multiphase reactors and lists the various reactor models reported to predict the overall performance of monolith reactors.