FLOW CHEMISTRY gas-liquid phase homogenisation along the height of the bed, enabling consistent and repeatable reaction outcomes. Zaiput identified an alternative pathway: achieving flow uniformity through a wide and shallow reactor bed, enabled by precise gas and liquid distribution at the reactor’ s inlet. The primary advantage of this approach is a significant reduction in pressure drop.
To address the challenges of pressure management, scalability and radial temperature gradients commonly encountered in fixed-bed systems, Zaiput has developed the Tower Reactor( TWR), a modular, layered reactor design( Figure 1). In the TWR, gas and liquid reactants are introduced from the bottom and evenly distributed across the active cross-sectional area. The biphasic mixture then flows upward in a cocurrent fashion, promoting effective mixing and reaction kinetics.
The system’ s modular architecture enables customised configurations tailored to process-specific requirements. Heat exchanger modules can be inserted to bring the reactants rapidly to target temperatures. Cartridges containing powdered catalyst material are then stacked above these exchangers.
This layered set-up is fully customisable. Users can define the order and number of layers based on reaction kinetics, heat management needs and process scale. Additional features, such as multiple liquid or gas inlets and removable modules, provide flexibility for a wide range of chemistries and operating conditions. A key feature is the integration of micro-engineered features to ensure high-quality gas-liquid distribution across the entire flow area. The feed distribution module plays a critical role in delivering both phases uniformly, eliminating common issues such as channelling or phase maldistribution. This enables the use of large, shallow catalyst beds, which significantly reduce pressure drop by minimising vertical flow velocity and bed height.
Additionally, passive mixing structures embedded within non-reactive modules( e. g. heat exchangers) continuously promote phase dispersion, ensuring that gas and liquid remain well mixed throughout the system. This design results in superior flow uniformity and temperature control, contributing to consistent catalytic performance, improved safety and more scalable operations.
TWR vs. traditional reactors
The TWR offers numerous advantages compared to traditional reactors, especially regarding heat management, configurability, catalyst flexibility and scale-up.
The axial heat exchanger module uniformly heats or cools the process fluid along the direction of flow. Unlike conventional jacketed reactors where heat transfers from the outside inward— often creating radial temperature gradients— this design achieves a highly uniform temperature profile across the entire reactor cross-section. Eliminating hotspots is particularly critical for exothermic reactions, enhancing reaction control and process safety.
The reactor’ s architecture allows chemists and engineers to adapt the reactor layout to the precise needs of their chemistry. Instead of adjusting the chemistry to fit a fixed hardware design, the reactor can be physically reconfigured in the lab to optimise reaction performance, heat management and scale.
The TWR is compatible with standard catalyst powders commonly used in batch processes. An engineered catalyst packing system equipped with sensors ensures uniform and reproducible packing into cartridges,
Catalyst cartridg
Heat exchange layers r as---.i needed
Process gas input
Process liquid input Figure 2- Pressure drop & heat transfer: Tower Reactor vs. beds
SEP / OCT 2025 SPECCHEMONLINE. COM
51