Differential Recycle Reactors for the Investigation of Heterogeneously Catalyzed Gas-Liquid Reactions under Industrially Relevant Conditions

Accurate kinetic data under industrially relevant conditions is critical for designing, optimizing, and scaling heterogeneous catalysis in gas-liquid reactions. Conventional laboratory methods often fail to replicate the hydrodynamics and thermal environments of industrial fixed-bed reactors, limiting their direct applicability.This work focuses on the Differential Recycle Reactor (DRR), a laboratory-scale concept designed to provide reliable kinetic data under well-defined fluid flow conditions comparable to industry. Operated in batch mode with external circulation, the DRR allows rapid variation of parameters while maintaining isothermal and homogeneous flow. Its geometry was optimized to ensure uniform catalyst bed porosity and prevent maldistribution, replicating key features of packed-bed systems.To enhance data quality, the DRR was equipped with inline benchtop NMR spectroscopy for real-time, non-invasive monitoring. A quantum mechanical model-based fitting approach enabled quantitative analysis of complex, overlapping signals without calibration, allowing detection of intermediates and minor species under relevant conditions. Validation with a representative gas-liquid reaction confirmed the DRR’s ability to deliver high-quality kinetic data in reduced timeframes. The resulting model shows the system can be described by a simple batch framework under defined conditions.The DRR, combined with advanced inline analytics, provides a flexible, scalable methodology for investigating heterogeneous catalysis. It supports faster process development, reduced experimental effort, and more reliable scale-up from laboratory to industrial reactors.