In view of a rising energy demand and a depletion of fossil raw material, the request for renewable feedstock for the energy and chemical market is growing. In a recent screening for innovative fuel candidates, 2-butanone has emerged as a promising alternative. In addition, 2-butanone is a component used mainly as solvent for paints and is primarily produced by dehydrogenation of 2-butanol, which is gained by hydration of n-butenes via petrochemical synthesis. Hence, a sustainable production of 2-butanone could open up several opportunities in bioeconomy.
However, a bio-based production route combining pretreatment, reaction and purification has not been investigated yet and thus the potential of bio-based 2-butanone production as a fuel is unknown. This contribution pursues a holistic analysis of alternative 2-butanone production routes. It relies on a screening of reaction pathways to identify promising routes, uses an incremental refinement of process synthesis steps  and thus provides an comparative overview of production processes including state-of-the-art heat integration and first results in terms of the economic potential for the production of 2-butanone. The design is based on sugars as feedstock for comparison to mature ethanol processes.
For the bio-based production of 2-butanone several alternative synthesis routes starting from glucose are conceivable from literature. First, mass balances for different routes are set up without detail design of separation in order to select the most promising path by means of the overall yield. A efficiency can be expected from the high titer and high productivities of 2,3-butanediol fermentation (,) and from high selectivity’s in the chemo-catalytic conversion by a solid-acid catalyst .The fermentation to 2,3-butanediol and dehydration to 2-butanone is thus pursued further.
In the next step, conceptual process design was performed including 2,3-butanediol fermentation, 2,3-butanediol separation, the dehydration reaction to 2-butanone and the following purification of the product. Due to multiple approaches for the separation step an incremental refinement approach is used to find a competitive production process. To this end, both well-known distillation processes as well as hybrid separation strategies seem feasible.
The process alternatives were evaluated by means of the energy demand i.e., based on the minimum energy calculations for distillation columns with reliable shortcut methods and optimistic assumptions in case of other unit operations. The most promising strategy is a heat integrated process, which shows an energy demand of 0.43 MJ/MJ2-butanoneafter pinch analysis and application of vapor recompression.
The analysis of the simulation of the processes identifies the separation of 2,3-butanediol as a high boiling constituent from the fermentation broth and the separation of mixtures with non-ideal distillation behavior as key issues of this route. If the costly water separation could be circumvented, 2-butanone unveils a potential in bioeconomy similar to that of ethanol.
In conclusion, this contribution identifies potentials and bottlenecks of bio-based 2-butanone production. Different reaction and separation routes involving alternative devices are compared. By this comparative analysis a production of 2-butanone via 2,3-butanediol is proposed. A hybrid separation concept for 2,3-butanediol separation, which consists of membrane separation, extraction and a distillation sequence, is the most promising process concept with 0.43 MJ/MJ2‑butanone. In comparison to the bio-ethanol production, this process concept seems competitive if an improvement of the separation of 2,3-butanediol from water is achieved.
This work was funded by the federal ministry of food and agriculture and was performed as part of the Cluster of Excellence "Tailor-Made Fuels from Biomass", which is funded by the Excellence Initiative by the German federal and state governments.
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