The influence of fluid dynamics on the selectivity of fast gas–liquid reactions in methanol

Journal
Chemical engineering and processing  
Volume
180
Article Number
108650
Citation
Chemical Engineering and Processing - Process Intensification 180: 108650 (2022-10)
Publisher DOI
10.1016/j.cep.2021.108650
Scopus ID
2-s2.0-85116115332
Publisher
Elsevier
One important strategy for process intensification is the enhancement of yield and selectivity in fast gas–liquid reactions, like oxidations, hydrogenations or halogenations. However, the interplay between fluid dynamics and competitive chemical reactions has not yet been understood to an extent that allows tailoring the flow and concentration fields for intensified reactions. To understand the interplay, the fluid dynamic conditions surrounding Taylor bubbles rising in an organic solvent are studied and compared to data of aqueous systems from the literature. The local flow fields are measured using Particle Image Velocimetry (PIV) and compared to spectroscopically derived selectivity data of a competitive consecutive gas–liquid reaction. The general rising behavior of Taylor bubbles in methanol is confirmed to be similar to those of bubbles in aqueous systems. However, as surface active agents do not affect the interface mobility in organic solvents, the local flow structures in the bubble wake differ significantly from those of bubbles rising in water, impacting the mixing behavior. Finally, the flow fields are compared to the concentration fields of the main and side products. Thereby, a decisive influence of the fluid dynamics on yield and selectivity becomes apparent, unveiling the potential for process intensification.
DDC Class
540: Chemie