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@PHDTHESIS{Harhues:988599,
author = {Harhues, Tobias},
othercontributors = {Wessling, Matthias and Vermaas, David A.},
title = {{P}rocess integration and intensification of
electrochemical reactions for biomass valorization},
volume = {44},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2024-06302},
series = {Aachener Verfahrenstechnik series - AVT.CVT - chemical
process engineering},
pages = {1 Online-Ressource : Illustrationen},
year = {2024},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2024},
abstract = {The consumption of fossil resources as the carbon feedstock
for the chemical industry is a major source of the global
CO2 emissions that can be counteracted by replacing fossil
carbon with sustainable sources such as hemicellulosic
biomass. However, the replacement requires novel processes
and, in part, products that have been proposed with the
concept of the biorefinery. Yet, these processes do not
include electrochemical conversion methods, as research on
electrochemical reactions has mostly been limited to the
catalyst and reactor levels. Their implementation into
process chains still needs to be demonstrated. This work
aims to integrate electrochemical processes into two process
chains to yield 2,5-furandicarboxylic acid (FDCA) and
2-butanone. It reveals the possibility of eradicating
intermediate purification steps when integrating
electrochemical conversion with the preceding chemocatalytic
or microbial processes. Additionally, a structured approach
towards paired electrolysis for biomass valorization is
presented and implemented to combine the two reactions and
show the potential to increase the energy efficiency of
paired electrolysis. For the reduction of acetoin to
2-butanone, the fermentation supernatant from the microbial
synthesis of acetoin was directly used as the electrolyte
without intermediate purification. The pH in the
electrochemical cell was adapted to the fermentation
supernatant, which resulted in a yield of $45\%.$ To
increase the yield further, the fermentation was carried out
in a minimal medium, leading to a yield of above $50\%$
2-butanone in the electrochemical conversion step.
Similarly, for the synthesis of FDCA,
hydroxymethylfurfural(HMF) was supplied to the
electrochemical cell via the organic product mixture of its
synthesis. In the cell, it was oxidized to FDCA in the
biphasic electrolytic system with a yield of over $70\%.$ A
so-called swiss roll reactor increased the space-time yield
by more than one order of magnitude compared to a planar
reactor at only very little loss of yield. Lastly, a
structured approach to pair the two electrochemical
reactions was developed. A stable process could be
established through the choice of a bipolar membrane and
appropriate reaction conditions. The product concentration
could be increased to industrially relevant values of up to
0.5 mol L-1 FDCA and 2-butanone at a yield above $90\%$ for
FDCA and $35\%$ for 2-butanone at a current density of 150
mA cm-2. With the integration of the electrochemical
processes with chemocatalytic and microbial process steps,
this work demonstrates that electrochemical reactions can be
integratedin to process chains to valorize biomass.
Moreover, electrochemical processes offer the possibility to
mitigate intermediate purification and increase the
efficiency of the process chain. The intensification of
these reactions through paired electrolysis can further
increase process efficiency so that the products and
processes based on sustainable carbons can contribute to the
defossilization of the chemical industry.},
cin = {416110},
ddc = {620},
cid = {$I:(DE-82)416110_20140620$},
pnm = {DFG project 390919832 - EXC 2186: Das Fuel Science Center
– Adaptive Umwandlungssysteme für erneuerbare Energie-
und Kohlenstoffquellen (390919832) / EFRE 0500077 - ELECTRA
- Kompetenzzentrum Industrielle Elektrochemie (0500077)},
pid = {G:(GEPRIS)390919832 / G:(EFRE)0500077},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2024-06302},
url = {https://publications.rwth-aachen.de/record/988599},
}
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