Enhanced Down-Stream Processing of Biobutanol in the ABE Fermentation Process

Abstract

Butanol is considered a superior biofuel, as it is more energy dense and less hygroscopic than bioethanol, resulting in higher possible blending ratios with gasoline. However, the production cost of the acetone-butanol-ethanol (ABE) fermentation process is high, mainly due to the low butanol titer, yield, and productivity in bioprocesses. The classic recovery by distillation is an energy-intensive process that has largely restricted the economic production of biobutanol. Other methods based on gas stripping, liquid-liquid extraction, adsorption, and membranes are also energy intensive due to the bulk removal of water. This study proposes a novel process for the butanol recovery by enhanced distillation, using only several operating units in an optimized sequence to reduce costs. This work considers a plant capacity of 40 ktpy and purities of 99.4 %wt butanol, 99.4 %wt acetone and 91.4 %wt ethanol. The process was simulated and optimized using Aspen Plus as PSE tool. The enhanced process proposed here is cost effective and can be readily employed at large scale to improve the economics of biobutanol production.