Eco-efficient butanol separation in the ABE fermentation process

Abstract

Keywords 11Downstream processing, distillation, dividing-wall column, optimal design, process control 12 13 Highlights 14• Energy efficient downstream processing in the acetone-butanol-ethanol (ABE) process 15• Cost effective distillation process for butanol separation and purification 16• Optimal process design including heat-integration, still robust and controllable 17 18 Abstract 19Butanol is considered a superior biofuel, as it is more energy dense and less hygroscopic than 20 the more popular ethanol, resulting in higher possible blending ratios with gasoline. However, 21 the production cost of the acetone-butanol-ethanol (ABE) fermentation process is still high, 22 mainly due to the low butanol titer, yield and productivity in bioprocesses. The conventional 23 recovery by distillation is an energy-intensive process that has largely restricted the economic 24 production of biobutanol. Other methods based on gas stripping, liquid-liquid extraction, 25 adsorption, and membranes are also energy intensive due to the bulk removal of water. 26This work proposes a new process for the butanol recovery by enhanced distillation (e.g. 27 dividing-wall column technology) using only few operating units in an optimized sequence to 28 reduce overall costs. A plant capacity of 40 ktpy butanol is considered and purities of 99.4 29 %wt butanol, 99.4 %wt acetone and 91.4 %wt ethanol. The complete downstream processing 30 was rigorously simulated and optimized using Aspen Plus. The enhanced process is effective 31 in terms of eco-efficiency (1.24 kWh/kg butanol, significant lower costs and emissions) and 32 can be readily employed at large scale to improve the economics of biobutanol production. 33

Optimal hybrid separations for intensified downstream processing of biobutanol

“…All the binary interaction parameters related to the property model are available in the pure components databank of the Aspen Plus process simulator. This was validated against experimental data by Patrascu et al [6].…”

“…In this respect, a combination of a decanter (exploiting the liquid phase split) or liquid-liquid extraction (LLX) combined with advanced distillation technologies, could be used to increase the concentration of the diluted stream and then purify the main product [5,6]. Other separation techniques that could be used include adsorption, gas stripping, vacuum flash, reverse osmosis (RO), perstraction, and pervaporation.…”

Novel distillation process for effective and stable separation of high-concentration acetone–butanol–ethanol mixture from fermentation–pervaporation integration process

“…A subsequent distillation system is still necessary for solvents purification [ 8 , 16 , 17 ]. Compared to the energy-intensive distillation that directly fed with the ABE fermentation broth, separation processes that coupled ISPR techniques with distillation could also significantly reduce the energy demand in ABE processes [ 11 , 18 , 19 ]. Lately, novel downstream processes such as vacuum separation–distillation [ 20 ], gas stripping–distillation [ 13 , 19 ], extraction–distillation [ 21 – 23 ], pervaporation–distillation [ 11 , 24 ] and the hybrid separations–distillation were well developed and deeply analyzed [ 13 ].…”

Isobaric Vapor Liquid Equilibrium Determination for 1,3,5-Trimethylbenzene + Ethanol and 1,3,5-Trimethylbenzene + n-Butanol Binary Systems

“…Liquid-liquid extraction, followed by distillation, is one of the processes that are highly likely to be used to separate butanol. Liquid-liquid extraction applied to ABE separation has been studied in several papers [21][22][23][24][25][26][27][28]. A good extraction solvent should have a high solubilization capacity, high selectivity towards butanol, a boiling temperature different from that of butanol and of the other solubilized components.…”

“…Other solvents that may be used for butanol extraction are higher alcohols such as hexanol [24], heptanol, octanol [22,23], but these alcohols are toxic to Clostridium bacteria, although they have a good solvating capacity. Another alcohol proposed and studied for butanol extraction is 2-ethyl hexanol [25]. In 2010, Kraemer [26] conducted a scan of the properties of certain compound (alcohols and alkanes) using CAMD (computer-aided molecular design) to determine the compatibility of butanol with these compounds in order to find a suitable solvent for the butanol extraction.…”