Scale-up of slurry Taylor flow microreactor for heterogeneous photocatalytic synthesis of azo-products†

Scaling-up of continuous-flow photocatalytic reactions is of great importance for widespread implementation in the industry. Despite several successful demonstrations for the homogeneous photochemistry, much less progress has been made on the heterogeneous photochemistry. Herein, we report the scale-up of slurry Taylor flow photosynthesis of azo-compounds (azoxybenzene and azobenzene) from nitrobenzene. Sizing-up strategy was applied to boost the throughput of the reactor, in combination with a high-power LED light source to provide effective irradiation. The effects of various operating parameters were investigated to achieve the best synergy of multi-phase flow, interphase transfer and photon transfer process. The scaled-up slurry Taylor flow process was finally validated on a 50 gram scale for azo-compounds, which was 22 times higher than the recently reported value. Furthermore, a correlation was proposed to predict the overall photocatalytic productivity during the scale-up. This work demonstrates a cost-effective and efficient scale-up methodology for the heterogeneous photosynthesis of azo-compounds.