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@PHDTHESIS{Haus:838773,
author = {Haus, Moritz Otto},
othercontributors = {Palkovits, Regina and Pich, Andrij},
title = {${N}$-{V}inyl-2-{P}yrrolidonmonomere auf {B}asis biogener
{C}arbonsäuren : {D}esign heterogener {K}atalysatoren und
{P}rozessbewertung},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2022-00749},
pages = {1 Online-Ressource : Illustrationen},
year = {2021},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2022; Dissertation, RWTH Aachen University, 2021},
abstract = {The utilization of biomass in chemical production continues
to attract scientific, political, and corporate attention
due to its potential for sustainable development – most
notably regarding CO2 emissions. However, as of today, an
integrated network of biomass-based conversion technologies,
which could mimic and rival the petrochemical sector,
remains under construction. Thus, the search for enabling
catalytic materials and effective value chains remains an
acute topic of chemical research. In this context, detailed
evaluations of the projected economic and environmental
impacts associated with bio-based production have also
gained traction. They serve as motivation for
decision-makers in politics and industry, whilst also
highlighting the critical trade-offs in biomass cultivation
forchemical applications. Within this broader context, the
thesis at hand discusses a two-step value chain from chosen,
biomass-based platform chemicals – dicarboxylic acids,
such as succinic acid – to N-vinyl-2-pyrrolidone (NVP)
monomers. The process starts by converting the acid
substrate with monoethanolamine and hydrogen in an aqueous
environment to generate an N-(2-hydroxyethyl)-2-pyrrolidone
intermediate. The latter undergoes subsequent gas-phase
dehydration to NVP so that water appears as sole by-product
in an idealized scenario. Together with the use of
recyclable, heterogeneous catalysts in both stages, this
allows for an efficient access to high-value,
nitrogen-containing monomers starting from biomass. First,
chapter 5.1 serves as an overview of the entire two-stage
conversion, which includes the underlying reaction networks,
the performance of commercial catalysts and the influence of
reaction conditions. Based on the presented results,
ruthenium on carbon (Ru/C, 5 wt. $\%$ metal) and
sodium-impregnated silica (Na2O/SiO2, molar ratio 1:20) were
established as benchmark catalysts for stage one and two,
respectively. While total yields around 0.7 molNVP mol-1
acid were achieved with these systems, improvements in
catalyst activity and selectivity are desirable. Especially,
the reduction of amide/imide intermediates in stage one of
the value chain necessitates harsh conditions (150-200 °C,
150 bar H2) and yields by-products from overreduction and
oligomerization .As shown in chapter 5.2, these issues were
partially overcome by optimized bimetallic catalysts
(Pt-Re/TiO2) due to the synergy between platinum and rhenium
in the reduction of carboxylic acid derivatives. In this
context, it is evident that rhenium oxides deposited on or
near Pt0-surfaces are partially reduced after catalyst
pretreatments in hydrogen. The density of the resulting
Pt0/ReOx-y active sites, which can be modified by the
catalyst preparation procedure, correlates with activity.
Most notably, the functionalization of the TiO2 surface with
ReOx species prior to the impregnation of a positively
charged Pt-complex led to the highest dispersion. When
rhenium was impregnated on a Pt/TiO2 parent material, on the
other hand, the density of active sites was determined by
the Pt-dispersion of the parent and the extent of Pt-surface
blocking by rhenium species. Given this structure-activity
relationship, further attention was devoted to the
complementary understanding of Na2O/SiO2 materials in the
second stage of the value chain (chapter 5.3). Thus, surface
silanols (Si-OH groups) and basic sites caused by sodium
impregnation were found to define this catalyst class. In
detail, optimal catalyst activity was achieved at low sodium
loadings, through the formation of weakly basic Si-ONa
following the preferential ion exchange of isolated Si-OH
groups. The excessive neutralization of surface silanols at
high sodium content was, however, counterproductive,
highlighting the role of Si-OH in substrate adsorption and
catalysis.Given the combined knowledge of these
investigations, chapter 5.4 explores the economic and
environmental merit of the proposed value chain based on
operating cost and life cycle assessment, respectively. The
early-stage evaluation based on realistic, but simplified
process simulations underlines the central role of catalyst
performance for the outcome in both categories. In detail,
improved hydrogenation catalysts (stage one, as compared to
Ru/C) alone may reduce the operating costs of biomass-based
NVP production by up to 27 $\%$ (4.59 kg-1NVP vs. 6.25
kg-1NVP, assuming 2.5 kg-1acid). While this reduction would
be necessary to compete with the best-case scenario of
fossil-based production at current succinic acid prices, a
further commercial development of the biomass-based platform
would likely reduce the costs of the proposed value chain.
Furthermore, the carbon credit of biomass as compared to
fossil feedstocks leads to a more favorable comparison in
terms of global warming impact (GWI). Here, the new value
chain may reduce the impacts of monomer production by at
least 41 $\%$ (as compared to the non-ideal fossil case,
e.g. 4.49 kgCO2 kg-1NVP vs. 7.60 kgCO2 kg-1NVP), if new
catalyst technologies and/or alternative, lignocellulosic
feedstocks can be implemented. Thus, further research and
scale-up testing is warranted.},
cin = {155310 / 150000},
ddc = {540},
cid = {$I:(DE-82)155310_20140620$ / $I:(DE-82)150000_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2022-00749},
url = {https://publications.rwth-aachen.de/record/838773},
}
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