Reaction Performance and Flow Behavior of Isobutane/1-Butene and H2SO4 in the Microreactor Configured with the Micro-mixer

The alkylation reaction of isobutane and 1-butene catalyzed by H2SO4 is a typical liquid-liquid heterogeneous reaction. Mass transfer is the limiting step. Configuring specific micro-mixing structures is useful to intensify the mass transfer and reaction performance in microchannels. A microreactor configured with contraction-expansion structures and triangular obstacles was used to improve the mixing and reaction performance of the isobutane alkylation process. The results show that the volumetric mass transfer coefficient in the microreactor configured with a micro-mixer was over 27 times of that in the stirring reactor and the reaction conversion reached 95.7% at only 12 s. In microchannels, hydrocarbons were dispersed in H2SO4 as droplets. In the microchannel configured with contraction-expansion structures and triangular obstacles, droplets could be effectively split and more than half of droplets were less than 0.4 mm. The specific interfacial area in the microchannel configured with contraction-expansion structures and triangular obstacles was 36% higher than that of the smooth microchannel. Moreover, the microreactor configured with contraction-expansion structures and triangular obstacles brought a strong velocity fluctuation, a big velocity difference between the hydrocarbon phase and the H2SO4 phase, and strong vortices in droplets. All these factors accelerated the surface renewal and greatly improved the mixing and mass transfer performance. The mechanism of droplet splitting under the synergetic effect of contraction-expansion structures and triangular obstacles was also studied. The research results are useful to design new microreactors for the reaction limited by mass transfer.