Techno-Economic Analysis of Upgrading Corn Stover-Based Acetone, n-Butanol, and Ethanol to Higher Ketones and Alcohols: Fuels or Fine Chemicals?

Abstract

Acetone−butanol−ethanol (ABE) fermentation is a traditional industrial exploitation with a history of 100 years and the second largest fermentation industry in the world, second only to bioethanol fermentation. However, low ABE concentration in the fermentation broth, a complex separation process, and high separation cost are the bottlenecks of the biobutanol industry. Therefore, developing an efficient and energy-saving ABE upgrading process gives another approach to the reindustrialization of ABE fermentation, even with the completeness of fossil resource-based products. Here, we report on a coupling salting-out catalytic process intensification technique in which acetone was alkylated with ethanol and 1-butanol by Pd/C + K 3 PO 4 , and the higher ketone and alcohol products were separated by the salting-out effect of K 3 PO 4 . The higher ketones and alcohols were experimentally obtained with >70% mass fractions at 200−250 °C under the fermentation-derived H 2 atmosphere and can be used as fuel precursors or fine chemicals. Aspen Plus was employed to simulate corn stover-based biobutanol production and the upgrading process through a series of analyses on raw materials cost, capital cost, operating cost, product selling prices, net present values, and sensitivities. A comparison between fuel precursors and fine chemicals was carried out, and fine chemicals turned out to be the preferred choice if the selectivity of the products and further purification process could be optimized. The results of a sensitivity analysis show that the ABE concentration process is one of the most energy-intensive processes. Reducing the costs of raw materials is one strategy to improve the completeness of ABE fermentation.

Optimization of the Pd-Catalyzed Alkylation of the Fermentation-Derived Oxygenates Acetone and Butanol toward Sustainable Aviation Fuel (SAF) Intermediates

“…Focusing on C11 selectivity, the statistical analysis suggested that C11 product formation increased by reducing C and increasing B , while there was no effect caused by the combination of the two. This is somehow contradictory to the trend observed by Xie et al, who found that an increase in Pd/C catalyst loading from 0.5 g/20 g ABE (2.5 wt %) to 1.5 g/20 g ABE (7.5 wt %) led to an increase in the product formation of higher ketones derived from alkylation. The authors noted, however, that increasing the catalyst loading to more than 10 wt % resulted in mass transfer problems during reaction, leading to lower results in terms of yield toward the formation of alkylation products.…”

“…No water was added as cosolvent in the present work, where the solvent was a reactant as well, thus making the final C higher than compared to the work by Xie et al Consequently, mass transfer limitations may also be the reason why higher activity (TON) was obtained in the present study with lower C . As for the B , the associated increase in double alkylation selectivity toward C11 was also seen in previous related studies, ,, as basicity promotes the alkylation to occur with the less reactive methyl group of the ketone . Moreover, as aldol condensation is base-catalyzed, higher B resulted in an increased overall alkylation efficiency.…”

“…In the present work, butanol is employed as the solvent for the alkylation reaction by using a higher proportion of the alcohol than that obtained in ABE fermentation (2 g of butanol per g of acetone). This is preferred instead of using external solvents such as toluene, as it allows for a higher conversion and selectivity toward further alkylation. , Potassium salts in the form of KOH and K 3 PO 4 are generally observed as superior base additives for the process, with K 3 PO 4 giving lower alcohol formation, albeit with a lower affinity for dialkylation compared to KOH. , However, the salting-out effect of K 3 PO 4 decreases the influence of water in the reaction. , For this reason, along with reduced alcohol formation, K 3 PO 4 was selected as the base additive in the present study.…”

“…8,29 However, the salting-out effect of K 3 PO 4 decreases the influence of water in the reaction. 30,31 For this reason, along with reduced alcohol formation, K 3 PO 4 was selected as the base additive in the present study. The comprehensive characterization of the effect of process conditions was complemented by a kinetic study with the aim to characterize the double alkylation of acetone toward C11, determining the rates of both reactions and the orders of reaction for every compound involved.…”