Innovative Reactive Distillation Process for the Sustainable Synthesis of Natural Benzaldehyde

Benzaldehyde (BA) is an aromatic flavor compound with a distinctive bitter almond taste and odor, being the second most produced and valuable natural fruit flavor (after vanillin). Compared to the chemical synthesis route, the BA production from natural resources is very expensive hence significant research effort has spurred into finding more feasible solutions. This study presents a novel reactive distillation (RD) process for the synthesis of natural BA by the alkaline hydrolysis reaction of cinnamaldehyde using β-cyclodextrin as phase transfer catalyst. A rigorous model of the RD process was developed for the plant design and scale-up, and pilot-scale experiments were used to validate the model. Also, a sensitivity analysis was performed to determine the effects of key operating variables on the RD process performance. The techno-economic analysis shows that the process is feasible, with over 97% and 70% reduction in CapEx and OpEx, over 88% savings in total annual costs, and 70% less CO₂ emissions as compared to the batch technology. Higher conversion and yield can be obtained by RD, within shorter residence time (only 2.9 h instead of 18 h) and using a lower reactants ratio (water:cinnamaldehyde = 11.5 instead of 200) as compared to the conventional process. However, the yield still needs to be further improved.