Prospects and challenges for the recovery of 2‐butanol produced by vacuum fermentation – a techno‐economic analysis

Abstract

The conceptual design of a bio-based process for 2-butanol production is presented for the first time. Considering a hypothetical efficient producing strain, a vacuum fermentation is proposed to alleviate product toxicity, but the main challenge is the energy-efficient product recovery from the vapor. Three downstream scenarios were examined for this purpose: 1) multi-stage vapor recompression; 2) temperature swing adsorption; and 3) vapor absorption. The processes were simulated using Aspen Plus, considering a production capacity of 101 kton/yr. Process optimization was performed targeting the minimum selling price of 2-butanol. The feasibility of the different configurations was analyzed based on the global energy requirements and capital expenditure. The use of integrated adsorption and absorption minimized the energy duty required for azeotrope purification, which represents 11% of the total operational expenditure in Scenario 1. The minimum selling price of 2-butanol as commodity chemical was estimated as 1.05 $/kg, 1.21 $/kg, and 1.03 $/kg regarding the fermentation integrated with downstream scenarios 1), 2), and 3), respectively. Significant savings in 2-butanol production could be achieved in the suggested integrated configurations if more efficient microbial strains were engineered, and more selective adsorption and absorption materials were found for product recovery.

Integrated Vacuum Stripping and Adsorption for the Efficient Recovery of (Biobased) 2-Butanol

“…At this point, the adsorbate within the column contained roughly 93 wt % 2-butanol, which is substantially higher than the azeotrope composition. The prospects for the adsorption-based recovery of 2-butanol produced by vacuum fermentation have been discussed in Pereira et al, 7 on the basis of preliminary data. The overall energy duty was estimated to be 21.9 MJ/kg with highly pure 2-butanol (99 wt %) as the final product.…”

“…This rate was calculated stoichiometrically, assuming a hypothetical 2-butanol volumetric productivity of 0.027 mol/(L h). 7 This rate translated into a CO 2 gas flow of ca. 13 ± 3 L/h, which was measured using a mass flow controller.…”

“…Additionally, 2-butanol/water systems form a homogeneous azeotrope, which cannot be separated using conventional distillation methods. 7 Although 2-butanol can be concentrated up to ca. 62 wt % by phase separation in a decanter, this composition is still below the azeotrope (ca.…”

Butanol production via vacuum fermentation: An economic evaluation of operating strategies

“…A number of different configurations of this compression arrangement have been considered in the literature (Abdi et al, 2016;Mariano et al, 2011;Pereira et al, 2017) and because of the high energy requirements of the process, the energy efficiency of the vacuum fermentation needs be improved using heat pump systems. In the process flowsheet, Fig.…”

Evaluación energética y económica de la recuperación in situ de butanol aplicando vacío cíclico en un reactor con múltiples alimentaciones

“…Sin embargo, esta tecnología aún tiene altos consumos energéticos. Por esta razón, en la literatura se han estudiado diferentes alternativas para la generación de vacío, los cuales incluyen sistemas de compresión con absorción y adsorción (Pereira et al, 2017(Pereira et al, , 2019, bombas de calor en múltiples etapas (Grisales-Díaz et al, 2019) y vacío cíclico (Mariano et al, 2012).…”