000220012 001__ 220012
000220012 005__ 20181007231410.0
000220012 0247_ $$2doi$$a10.5075/epfl-thesis-7100
000220012 02470 $$2urn$$aurn:nbn:ch:bel-epfl-thesis7100-8
000220012 02471 $$2nebis$$a10684140
000220012 037__ $$aTHESIS_LIB
000220012 041__ $$aeng
000220012 088__ $$a7100
000220012 245__ $$aCarbon dioxide for hydrogen storage via formic acid derivatives and methanol
000220012 269__ $$a2016
000220012 260__ $$aLausanne$$bEPFL$$c2016
000220012 300__ $$a193
000220012 336__ $$aTheses
000220012 502__ $$aProf. Andreas Osterwalder (président) ; Prof. Gabor Laurenczy (directeur de thèse) ; Prof. Lothar Helm, Prof. Yuichiro  Himeda, Dr Luca Gonsalvi (rapporteurs)
000220012 520__ $$aSecuring our energy future while minimizing the associated environmental impacts is a challenging endeavor and the fundamental aspect of sustainable development. The choice of energy resource and the reduction of greenhouse gas emissions, primarily carbon dioxide (CO2), are key parameters in this process. Hydrogen gas (H2) is an energy carrier with the potential of "green" production and utilization, in addition to having attractive inherent fuel properties. However, complications during its storage arise from its intrinsically light nature. Chemical H2 fixation within liquid formic acid (FA) and its derivatives is therefore a promising approach. In the present dissertation, reversible H2 storage cycles based on homogeneous FA/formate dehydrogenation and CO2/bicarbonate hydrogenation, as well as the related CO2 transformation to methanol are investigated. The first chapter provides an overview of challenges underlying energy sustainability, prospects for integration of H2 with our energy infrastructure, the employment of FA as a liquid organic hydrogen carrier and state of the art homogeneous catalysts for selective FA dehydrogenation and CO2 hydrogenation. The combination of these reactions to form a closed CO2 loop is the basic concept behind a reversible H2 storage system as it is envisaged by our group. In the second chapter, FA dehydrogenation/formation in the presence of triethylamine is discussed. The results are summarized as equilibrium positions within this couple, which can be controlled by adjustment of the operating pressure and temperature. The basic additive promotes H2 fixation but also allows for on-demand H2 release from a triethylammonium formate substrate. The third chapter addresses H2 storage in basic media, i.e. aqueous bicarbonate hydrogenation, with a Ru(III) catalyst precursor and a number of water-soluble phosphine ligands. The latter are introduced to tailor the exhibited activity by affecting the steric and electronic parameters of the catalyst. All phosphines provide high bicarbonate conversions, albeit with low reaction rates. Chapter four summarizes the optimization and mechanistic studies of the reversible formate dehydrogenation reaction, in the presence of a Ru(II)-mTPPTS catalyst. Cesium is chosen as the cation for the formate/bicarbonate salts because it leads to their high solubility in the aqueous solvent and therefore an increase in the hydrogen storage capacity. The involved equilibria are determined and a reaction mechanism for the formate dehydrogenation step is proposed, based on NMR studies. Advantages of the presented approach include the utilization of water as the solvent, the absence of CO2 throughout the reactions and the successful in situ recycling of the environmentally benign hydrogen carrier. In Chapter five the feasibility of producing both FA and methanol directly from CO2, at room temperature, in a "one-pot" reaction using aqueous solvent is demonstrated. Formic acid formation occurs in water without additives or organic solvents with a homogeneous iridium catalyst. Formic acid also undergoes disproportionation into methanol, with the same complex. Under optimized conditions, FA conversions of 98% and methanol selectivities of 96% are achieved in the disproportionation reaction. These reactions are relevant to the field of sustainable H2 storage, but might also provide an alternative approach to the commercial fossil-fuel-dependent production of formic acid and methanol.
000220012 6531_ $$aAqueous solution
000220012 6531_ $$acarbon dioxide
000220012 6531_ $$acesium bicarbonate
000220012 6531_ $$acesium formate
000220012 6531_ $$adisproportionation
000220012 6531_ $$aformic acid
000220012 6531_ $$ahomogeneous catalysis
000220012 6531_ $$ahydrogen storage
000220012 6531_ $$amethanol
000220012 700__ $$0246501$$aSordakis, Katerina Stefania$$g221936
000220012 720_2 $$0240013$$aLaurenczy, Gabor$$edir.$$g123171
000220012 8564_ $$s7742079$$uhttps://infoscience.epfl.ch/record/220012/files/EPFL_TH7100.pdf$$yn/a$$zn/a
000220012 909C0 $$0252010$$pLCOM$$xU9
000220012 909CO $$ooai:infoscience.tind.io:220012$$pDOI$$pSB$$pthesis$$qDOI2$$qthesis-bn2018
000220012 917Z8 $$x108898
000220012 917Z8 $$x108898
000220012 917Z8 $$x108898
000220012 917Z8 $$x108898
000220012 918__ $$aSB$$cISIC$$dEDCH
000220012 919__ $$aLCOM
000220012 920__ $$a2016-7-18$$b2016
000220012 970__ $$a7100/THESES
000220012 973__ $$aEPFL$$sPUBLISHED
000220012 980__ $$aTHESIS