Bifunctionalised acid-base hierarchically structured monolithic micro-/mesoreactors for continuous-flow tandem catalytic processes. A case study of cyanocinnamate synthesis

Abstract The results on zirconia-amine bifunctional modification of hierarchically porous silica monoliths for continuous-flow processes are presented. The study reports the synthesis and properties of the modified porous monoliths and their performance in tandem process of deacetalisation-Knoevenagel condensation reaction. Thermal and FTIR spectroscopy analyses and activity studies were carried out. It was found that the both active centres were uniformly distributed along the monolithic cores. The performance of the bifunctional microreactors was checked and compared with cascade-connected monofunctional microreactors and batch reactor. The yield of cyanocinnamate product obtained in both flow systems was comparable - c.a. 78%, however flow resistance/pressure drop in the bimodified reactor was only half of that in cascade. The effective way of water supply to the continuous flow catalytic system has been proposed. The research demonstrates the benefits of using flow-through structured micro-/mesoreactors to boost tandem reaction processes.