Many types of chemical processes involve a heterogenous reaction mixture where either a solid-state reagent is used (i.e. heterogenous catalysis) or a reaction product is formed as a precipitate. Heterogenous catalysis encompasses a wide range of catalytic solids such as precious metal-based catalysts with platinum, palladium, nickel, and ruthenium that are highly relevant within industrial processes such as the production of pharmaceutical APIs and fine chemicals.

Traditional batch reactors are energy-intensive, with much greater heating and cooling requirements compared to continuous flow reactors due to having inherently lower heat-transfer coefficients. With the growing drive to transition the chemical manufacturing industry towards more environmentally friendly continuous manufacture in flow, there is a requirement to be able to perform existing heterogenous reactions in flow reactors.

The presence of solid particles within flow reactors such as “microchannel” or “packed-bed reactors” can lead to issues such as bridging, settling, and fouling which can all result in reactor blocking, leading to a complete breakdown of the flow system and the prevention of material flowing through the reactor.

Handling solids under flow conditions requires reactors with a simple internal geometry, as well as channel diameters that are large enough to prevent bridging. Good mixing is also essential to maintain a uniform solids-liquid dispersion. In horizontal transfer lines, good mixing is required to keep solids suspended and moving, and for which high axial velocity with turbulent flow is required. Stagnant pockets where solids can settle out need to be eliminated by keeping the diameter of the channels uniform, and by using long-radius bends.

Coflore® flow reactors from AM Technology are actively mixed and multi-stage reactors with efficient plug flow characteristics. Mixing efficiency and plug flow performance are independent of residence time facilitating reaction times ranging from a few seconds to many hours, irrespective of pump flow rate or process fluid velocity.

Coflore reactors are engineered to handle solids in flow through the use of free moving agitators within the process channels, which generate the required efficient radial mixing via rapid transverse movement of the flow reactor block. Good mixing, combined with a simple cell geometry, and comparatively large inter-stage channels, provide an effective means of keeping slurries flowing through the reactor.

Several recent peer-reviewed publications within the scientific literature have demonstrated the ability to successfully handle solids in flow using Coflore reactors some of which are linked below. If you have an existing batch chemical process and are looking at transitioning to continuous manufacture in flow or are looking to scale up an R&D process to kilo-lab or production scale, please email Dr Mike Kenny of AM Technology at info@amt.uk.

Examples of solid-handling reactions with Coflore systems

1)   Effective Phosphorylation of 2,2′-Methylene-bis(4,6-di-tert-butyl) Phenol in Continuous Flow Reactors

2)   Fully Continuous Flow Synthesis of 5-(Aminomethyl)-2-methylpyrimidin-4-amine: A Key Intermediate of Vitamin B1

3)   Continuous Flow Process for Reductive Deoxygenation of ω-Chloroketone in the Synthesis of Vilazodone