Recovery of biologically produced 3-hydroxypropionaldehyde and its dehydrated product acrolein

3-Hydroxypropionaldehyde (3-HPA), which can be derived from biomass, is an important precursor for low-cost, large-volume acrolein-based chemicals like acrylic acid and acrylamide with a wide range of applications. In order to find an efficient process for isolating 3-HPA from fermentation broth, we comparatively investigated several separation methods including precipitation with hydrazides, immobilization with amines, reactive extraction with thiols, extraction with hydrophilic solvents, and reactive distillation as acrolein. It turned out that the reactive distillation is the most efficient method for in situ recovery of 3-HPA as acrolein. In a reactive distillation process at 37°C and Hammett acidity H0 = –1, the aldehyde concentration was reduced to 6 ± 1 mM in the transformation medium and increased to 1866 ± 146 mM in the distillate. The yield was 96 ± 8%. These experimental results are close to the calculated ideal equilibrium results assuming total dehydration of 3-HPA to acrolein. The main advantages of the reactive distillation process are that the recovery, purification, and concentration of acrolein are carried out in one step and the process is well suited for large-scale production at low costs.