Sustainable Purification of Butanol from a Class of a Mixture Produced by Reduction of Volatile Fatty Acids

Abstract

There has been an increasing interest in the conversion of biomass to biofuels, energy, and chemicals due to an increase in meeting environmental demands and price and decrease in the potential availability of crude oil. Among the biofuels postulated as viable alternatives due to their physicochemical characteristics is butanol. Given its high energy content, it is projected as a potential substitute for ordinary gasoline. However, butanol production process through fermentation of lignocellulosic material has shown some disadvantages. Another way of producing butanol is by reduction of volatile fatty acids (from waste streams of organic matters) with hydrogen. An effluent with a high content of water and butanol is obtained. In that sense, thermodynamic interactions make the separation process challenging. On the other hand, current policies and needs have guided the proposals for chemical processes to meet various sustainability metrics, for example, high profit margins and low environmental impact, with inherent safety and robust operation in the presence of disturbances. With this in mind, this work proposes purification schemes to obtain butanol of high purity, from a butanol–water mixture, in the compositions generated by reduction of volatile fatty acids, using pervaporation, pressure swing distillation, and azeotropic distillation. Comparing the results obtained, the pervaporation scheme turned out to be the most promising alternative as it presents reductions in all the “green” indicators (compared to the other purification alternatives) in percentages between 27 and 52%. The general indices for such alternative were 0.0392 ($/kgbutanol), 0.0066 (ecopoints/kgbutanol), 8274, 2.772 × 10–04 (probability/year), and 0.4281 $/kgbutanol regarding the total annual cost, ecological indicator 99, condition number, individual risk, and minimum selling price, respectively.

Analyzing the sustainability of intensified side‐stream extractive distillation for binary azeotropic separation: a comparative study

“…This observation agrees with an existing study with similar findings 61 . To further reduce the IR, several existing studies have recommended using less equipment, like in the DWC, to reduce the probability of catastrophic events 4,55 …”

“…61 To further reduce the IR, several existing studies have recommended using less equipment, like in the DWC, to reduce the probability of catastrophic events. 4,55 As for the control properties, the CN of both intensified processes increases, which generally signifies a worsened controllability for the intensified processes, meaning that a more complex control structure is required. This is expected for the preserved configuration because it has been well reported that the column configuration is strongly linked to an exact composition mixture that affects the control properties of a process.…”

“…The EI99 measures the environmental impact initiated by the activities carried out in the process. Today, the EI99 is widely used by different researchers globally to quantify the complete environmental performance of a given chemical processes and promote sustainable design 4,55 . It considers 11 impact categories that belong to three major damages, involving human health, ecosystem quality, and resource depletion, and is given by Eqn.…”

Towards sustainable separation and recovery of dichloromethane and methanol azeotropic mixture through process design, control, and intensification

“… is a diagonal matrix, which comprises of the singular values of K. To date, several existing studies have employed the usage of CN for evaluating the dynamic characteristic and operational flexibility of the different chemical processes 35‐37 . The process with a lower conditional number (or a higher minimum singular values) [Eqn (3)] generally signifies better dynamic characteristics under disturbance 13,38 . In this work, σ max and σ min are calculated with the M atlab program using the temperature difference obtained from the sensitivity analysis (see Section 3.3).…”

“…[35][36][37] The process with a lower conditional number (or a higher minimum singular values) [Eqn (3)] generally signifies better dynamic characteristics under disturbance. 13,38 In this work, ⊞ max and ⊞ min are calculated with the MATLAB program using the temperature difference obtained from the sensitivity analysis (see Section 3.3).…”