Intensification of fast exothermic reaction by gas agitation in a microchemical system

Abstract

The Beckmann rearrangement of cyclohexanone oxime in oleum as a fast exothermic reaction model is carried out in an adiabatic multiphase microchemical system. A severe coalescene is observed due to the high viscosity of the rearrangement mixture, which decreases the reaction rate and selectivity. Gas agitation is introduced into the microsystem to enhance the reaction by reducing the coalescene and providing an evaporation space to carry away reaction heat. The effects of gas agitation on dispersion performance and mass-transfer rate have been investigated. The acid droplets diameter ranges from about 44 to 20 mm, decreasing with the increase of the gas flow rate. The overall volume masstransfer coefficient in the microsystem ranges from 0.16 to 0.74 s 21 , 1.5-3.8 times larger than that without gas agitation. The reaction performance is evaluated under different conditions and better conversion and selectivity are obtained.

Droplet formation of H2SO4/alkane system in a T‐junction microchannel: Gravity effect

“…However, H 2 SO 4 is a common acid catalyst and widely used in the industrial processes, such as alkylation, rearrangement, and Claisen–Schmidt reaction . Applications in microchannels with H 2 SO 4 have been extensively investigated . In addition, the property of the H 2 SO 4 /alkane system is quite different from that of aqueous/oil systems.…”

Manipulation of gas-liquid-liquid systems in continuous flow microreactors for efficient reaction processes

“…Gas-liquid-liquid operation in microreactors has received increasing research attention over recent years with promising results being obtained in the targeted applications in among others three-phase reactions [11,[29][30][31][32][33][34], gas-liquid reaction coupled with in-situ extraction [21], inert gas assisted liquidliquid reaction study [32,35,36] and multistep synthesis (e.g., for making nanoparticles) [19,37,38]. As previously mentioned, gas-liquid-liquid reaction requires a fine control over the three-phase contact pattern and the associated mass transfer property for obtaining a favorable performance.…”

Liquid–liquid mixing enhancement rules by microbubbles in three typical micro-mixers

“…Other than these direct energy input approaches, the introduction of inert fluid is another simple but effective method to intensify mixing process. The purpose of introducing inert fluid, such as gas (Günther et al, 2005;Zhang et al, 2014) or unreactive oil (Matsuyama et al, 2007), is to change the flow pattern of microchannel at low Re number, producing inner circular flow in segmented liquid plugs. Matsuyama et al (2007) showed an example using silicone oil as the enhancing medium in a capillary mixer.…”