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

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 + K3PO4, and the higher ketone and alcohol products were separated by the salting-out effect of K3PO4. The higher ketones and alcohols were experimentally obtained with >70% mass fractions at 200-250 degrees C under the fermentation-derived H2 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.

Automated summary

Acetone-butanol-ethanol (ABE) fermentation is a traditional industrial process, but faces challenges such as low ABE concentration, complex separation process, and high separation cost. In this study, a salting-out catalytic process was developed to upgrade ABE fermentation products. Experimental results showed that high ketones and alcohols could be obtained and used as fuel precursors or fine chemicals. Simulation and analysis indicated that fine chemicals were the preferred choice if product selectivity and purification process were optimized. Sensitivity analysis revealed that the ABE concentration process is energy-intensive and reducing raw material costs can improve the completeness of ABE fermentation.