Continuous Flow Microreactors for the High-efficiency Enzymatic Synthesis of 10-Hydroxystearic Acid from Oleic Acid

Converting fatty acids into specialty chemicals is sustainable but hindered by the low efficiency and thermal instability of current oleic acid hydratases, along with mass transfer limitations in emulsion reactions. This study introduces an optimized continuous flow micro-reactor (CFMR) that efficiently transforms oleic acid at low (15 g L^-1) and high (50 g L^-1) concentrations, improving reaction efficiency and overcoming key conversion barriers. The first CFMR model showed reaction speeds surpassing traditional batch stirred tank reactors (BSTR). Optimizations were performed on three key components: liquid storage, mixer, and reaction section of the CFMR, with each round's best conditions carried into the next. This achieved a space-time yield of 597 g L^-1 d^-1 at a 15 g L^-1 oleic acid load. To further enhance the yield, we optimized the emulsifier system to solve incomplete emulsification and developed a two-component feed microreactor (TCFMR) that addressed mass transfer limitations caused by the product at high substrate loads, reaching a 91 % conversion of 50 g L^-1 oleic acid in 30 minutes, with a space-time yield of 2312 g L^-1 d^-1. These advancements represent significant progress in utilizing fatty acids and advancing sustainable chemical synthesis.