Magnetic resonance imaging of single- and two-phase flow in fixed-bed reactors

摘要

Magnetic resonance imaging and flow visualization techniques are increasingly used to study transport processes in chemical and biochemical reactors. Three recent case studies from our own research program are reported, each illustrating quite different applications of magnetic resonance techniques in such applications. First, two-phase flow in a trickle-bed reactor is considered. Images of the steady-state gas-liquid distribution are obtained which yield quantitative measures of liquid holdup and wetting efficiency. Second, a radiofrequency pulse sequence based on that for rapid acquisition with relaxation enhancement is used to perform ultrafast visualization of gas-liquid flow in individual channels within a ceramic monolith. Finally, H-1 volume-selective nuclear magnetic resonance spectroscopy is employed to perform an in situ spatially resolved study of the extent of conversion of the liquid-phase esterification reaction of methanol and acetic acid, catalyzed by an acid catalyst (Amberlyst 15 ion exchange resin) in a fixed-bed reactor. In particular, the effect of the superficial flow rate of the feed on conversion is investigated. [References: 17]