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@PHDTHESIS{Wohland:962754,
author = {Wohland, Julia Patricia},
othercontributors = {Palkovits, Regina and Liauw, Marcel},
title = {{S}upported mono- and bimetallic catalysts for the
${CO}_{2}$ - oxidative dehydrogenation of propane to
propylene},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2023-07603},
pages = {1 Online-Ressource : Illustrationen, Diagramme, Karte},
year = {2023},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2023},
abstract = {The necessity to reduce CO2 emissions of chemical processes
and to direct the chemical industry towards a circular
economy is becoming more significant every day, also
affecting the production of crucial basic chemicals like
propylene. The integration of CO2 into the conventional
production route of direct propane dehydrogenation to
produce propylene can reduce the carbon footprint of the
current process. Up to now, however, no qualified catalysts
are available, and the reaction system is prone to side
reactions. Thus, this work focusses on the development of a
suitable catalyst for the CO2- oxidative dehydrogenation of
propane to propylene (CO2-ODHP) and the thorough
investigation of the reaction system. The catalyst
development was based on the concept of supported mono- and
bimetallic catalysts. Prior to the development and
investigations, the qualification of the underlying system
including its reproducibility in synthesis and reaction was
successfully confirmed. Process parameters were reviewed,
and the reaction temperature was set to 600 °C and the CO2
: propane : inert gas ratio to 2:1:1 to work in a regime of
optimal catalyst performance. Within a catalyst screening
procedure, the two catalyst lead structures Ni3Fe/SiO2 and
Ni3Mo/ZrO2 were identified as promising candidates and their
performance improved in a second optimization step. A high
steady-state performance for Ni3Fe/SiO2 of $11.8\%$ propane
conversion and $1.8\%$ propylene yield was reached while
Ni3Mo/ZrO2 stood out with a propylene selectivity of
$21.8\%$ and a reduction in dry reforming as side reaction.
Molar metal ratio, metal loading, and calcination method
were identified as key synthesis parameters for an optimized
catalyst performance. Structure-activity investigations of
the two lead structures demonstrate that CO2 conversion and
CO formation both correlate with the concentration of weak
basic sites and that a maximum propylene yield is reached
for an acidic site concentration of 0.1 mmol per gram
catalyst. Beside the common causes coke formation and metal
particle sintering, competitive adsorption of CO2 and
propane were identified as major factors for catalyst
deactivation. In an in-depth mechanistic study of the
CO2-ODHP on Ni3Mo/ZrO2, analysis of the catalyst and the
activation of CO2 and propane suggest that the material can
catalyze both, the direct dehydrogenation, and the
CO2-oxidative dehydrogenation of propane via a redox or a
Mars-van-Krevelen mechanism. Based on the findings, a
guideline for catalyst design for enhanced performance in
the CO2-ODHP was given. Lastly, kinetic investigations
provide the first kinetic model on the interplay of
catalyzed main and side reactions in the CO2-ODHP. The model
moreover reveals that not only dry reforming of propane but
also propylene is responsible for the reduced yield and
provides additional factors to consider in catalyst design
such as easy product desorption.},
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-2023-07603},
url = {https://publications.rwth-aachen.de/record/962754},
}
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