Mathematical Modeling of Fines Migration and Clogging in Porous Media Guido Kampel 87 Pages Directed by Dr. Guillermo H. Goldsztein A porous medium is a material that contains regions filled with fluid embedded in a solid matrix. These fluid filled regions are called pores or voids. Suspensions are fluids with small particles called fines. As a suspension flows through a porous material, some fines are trapped within the material while others that were trapped may be released. Filters are an example of porous media. We model filters as networks of channels. As a suspension flows across the filter, particles clog channels. We assume that there is no flow through clogged channels. In the first part of this thesis, we compute a sharp upper bound on the number of channels that can clog before fluid can no longer flow through the filter. Soil mass is another example of porous media. Fluid in porous media flows through tortuous paths. This tortuosity and inertial effects cause fines to collide with pore walls. After each collision, a particle looses momentum and needs to be accelerated again by hydrodynamic forces. As a result, the average velocity of fines is smaller than that of the fluid. This retardation of the fines with respect to the fluid may lead to an increase of the concentration of fines in certain regions which may eventually result in the plugging of the porous medium. This effect is of importance in flows near wells where the flow has circular symmetry and thus, it is not macroscopically homogeneous. In the second part of this thesis we develop and analyze a mathematical model to study the physical effect described above. In the third and last part of this thesis we study particle migration and clogging as suspension flows through filters by means of numerical simulations and elementary analysis. We explore the effect that network geometry, probability distribution of the width of the channels and probability distribution of the diameter of the particles have on the performance of filters.

Under certain circumstances pulse combustors have been shown to improve both heat transfer and drying rate when compared to steady flow impingement. Despite this potential, there have been few investigations into the use of pulse combustor driven impingement jets for industrial drying applications. The research presented here utilized experimental and numerical techniques to study the heat transfer characteristics of these types of oscillating jets when impinging on solid surfaces and the heat and mass transfer when drying porous media. The numerical methods were extensively validated using laboratory heat flux and drying data, as well as correlations from literature. As a result, the numerical techniques and methods that were developed and employed in this work were found to be well suited for the current application. It was found that the pulsating flows yielded elevated heat and mass transfer compared to similar steady flow jets. However, the numerical simulations were used to analyze not just the heat flux or drying, but also the details of the fluid flow in the impingement zone that resulted in said heat and mass transport. It was found that the key mechanisms of the enhanced transfer were the vortices produced by the oscillating flow. The characteristics of these vortices such as the size, strength, location, duration, and temperature, determined the extent of the improvement. The effects of five parameters were studied: the velocity amplitude ratio, oscillation frequency, the time-averaged bulk fluid velocity at the tailpipe exit, the hydraulic diameter of the tailpipe, and the impingement surface velocity. Analysis of the resulting fluid flow revealed three distinct flow types as characterized by the vortices in the impingement zone, each with unique heat transfer characteristics. These flow types were: a single strong vortex that dissipated before the start of the next oscillation cycle, a single persistent vortex that remained relatively strong at the end of the cycle, and a strong primary vortex coupled with a short-lived, weaker secondary vortex. It was found that the range over which each flow type was observed could be classified into distinct flow regimes. The secondary vortex and persistent vortex regimes were found to enhance heat transfer. Subsequently, transition criteria dividing these regimes were formed based on dimensionless parameters. The critical dimensionless parameters appeared to be the Strouhal number, a modified Strouhal number, the Reynolds number, the velocity amplitude ratio, and the H/Dh ratio. Further study would be required to determine if these parameters offer similar significance for other configurations.

Existing numerical techniques for modeling saturated deformable porous media are based on homogenization techniques and thus are incapable of performing micro-mechanical investigations, such as the effect of micro-structure on the deformational characteristics of the media. In this research work, a numerical scheme is developed based on the parallelized hybrid lattice-Boltzmann finite-element method, that is capable of performing micro-mechanical investigations through direct numerical simulations. The method has been used to simulate compression of model saturated porous media made of spheres and cylinders in regular arrangements. Through these simulations it is found that in the limit of small Reynolds number, Capillary number and strain, the deformational behaviour of a real porous media can be recovered through model porous media when the parameters porosity, permeability and bulk compressive modulus are matched between the two media. This finding motivated research in using model porous geometries to represent more complex real porous geometries in order to perform investigations of deformation on the latter. An attempt has been made to apply this technique to the complex geometries of ªfeltº, (a fibrous mat used in paper industries). These investigations lead to new understanding on the effect of fiber diameter on the bulk properties of a fibrous media and subsequently on the deformational behaviour of the media. Further the method has been used to investigate the constitutive relationships in deformable porous media. Particularly the relationship between permeability and porosity during the deformation of the media is investigated. Results show the need of geometry specific investigations.

Solid-fluid thermal interactions during unsteady flow in porous media play an important role in the regenerators of pulse tube cryocoolers. Pore-level thermal processes in porous media under unsteady flow conditions are poorly understood. The objective of this investigation is to study the pore-level thermal phenomena during pulsating flow through a generic, two-dimensional porous medium by numerical analysis. Furthermore, an examination of the effects of flow pulsations on the thermal dispersion and heat transfer coefficient that are encountered in the standard, volume-average energy equations for porous media are carried out. The investigated porous media are periodic arrays of square cylinders. Detailed numerical data for the porosity range of 0.64 to 0.84, with flow Reynold's numbers from 0-1000 are obtained. Based on these numerical data, the instantaneous as well as cycle-average thermal dispersion and heat transfer coefficients, to be used in the standard unsteady volume-average energy conservation equations for flow in porous media, are derived. Also, the adequacy of current applied cycle-average correlations for heat transfer coefficients and the inclusion of the thermal dispersion in the definition of an effective fluid thermal conductivity are investigated.

Open-framework inorganic and inorganic-organic hybrid materials constitute an important area of study in materials chemistry, because of their potential applications in areas such as sorption and catalysis. Besides aluminosilicate zeolites, the metal phosphates and carboxylates constitute large families of open-framework structures. The possibility of building open architectures with the sulfate and selenate anions as the basic building units has been explored in this thesis. Investigations of a variety of open-framework metal sulfates and selenates, as well as a family of jarosites of different transition metals are presented. More importantly, studies directed towards the synthesis and understanding of the magnetic properties of various Kagome compounds formed by the transition metal ions is discussed at length. After providing an introduction to inorganic open-framework compounds (Part 1), the thesis presents the results of the investigations of various transition and rare earth metal sulfates with diverse structures and dimensionalities in Part 2. Some of these compounds show interesting properties. For example, a two-dimensional Ni(II) sulfate exhibits ferrimagnetism whereas a three-dimensional Ni(II) sulfate with 10-membered channels is paramagnetic. A family of three-dimensional co-ordination polymers of Co(II) sulfate wherein the Co(II) sulfate layers are linked by diaminoalkanes of varying chain length has been synthesized and characterized. Organically-templated neodymium and thorium sulfates with layered and three-dimensional structure have also been prepared. The jarosite family of compounds with the Kagome structure is considered as an ideal model for studying frustrated magnetism. This type of materials, however, is difficult to prepare in a pure and highly crystalline form. We have synthesized analogues of the jarosite containing magnetic ions other than Fe3+ by solvothermal techniques and discussed them in Part 3. In particular, we have prepared and explored the magnetic properties of Mn2+(S = 5/2), Fe2+ (S = 2), Co2+(S = 3/2) and Ni2+ (S = 1) jarosites. Based on the results presented, it becomes clear that the magnetic properties vary with the spin of the transition metal ion. It appears that those Kagome compounds with transition metalions with non-integer spins show antiferromagnetic interactions and magnetic frustration while those with integer spins exhibit ferro/ferrimagnetic properties. A theoretical study has also supports this observation. We have been able to isolate for the first time 1,4-diazacubane as the part of the structure of the nickel Kagome compound. The possibility of building open architectures with the selenate anion as the basic building unit has been explored in Part 4. The results have been rewarding and an organically-templated three-dimensional lanthanum selenate with 12-membered channels has thus been obtained for the first time.

Die vorliegende Arbeit befasst sich mit der Inkorporation von Metall-/ Metalloxidnanopartikeln in organisch-anorganischen Hybridmaterialien, dargestellt durch Zwillingspolymerisation. Dabei wurden verschiedene Lösungsansätze bearbeitet. Zum einen wurden Metalcarboxylate oder Metallocene verwendet, zum anderen konnten durch Variation der anorganischen Komponente des Zwillingsmonomeres entsprechende Nanopartikel erzeugt werden. Um die Nanopartikel stabilisierenden Eigenschaften, der aus Zwillingspolymeren zugänglichen porösen Kohlenstoffmatrix zu erhöhen sollten mittels Zwillingspolymerisation N-Donoren eingeführt werden Neben der Inkorporation von Nanopartikeln wurden auch Silber und Goldnanopartikel in einer porösen Kohlenstoffmatrix verkapselt. Dabei wurde gezeigt, dass der Verwendete Templatdurchmesser einen entscheidenden Einfluss auf die späteren Hohlkugeln hat. Es konnte ebenso mit Hilfe von einfachen Benchmarkreaktionen die Zugänglichkeit und katalytische Aktivität der eingekapselten Nanopartikel nachgewiesen werden. Es wird gezeigt, dass durch Verwendung von Triphenylphosphan-stabilisierten Silber(I)-carboxylaten eine Funktionalisierung von Zwillingspolymeren möglich ist. Außerdem sind aus dem so modifizierten Hybridmaterialien nach Karbonisierung sowie dem Herauslösen der anorganischen SiO2-Komponete entsprechende mikroporöse, silberhaltige Kohlenstoffmaterialien zugänglich, während durch oxidativen Abbau der organischen Polymermatrix mesoporöse mit Ag-Nanopartikeln infiltrierte SiO2-Materialien dargestellt werden können. Es werden spezifische Oberflächen von 1034 m2/g (Kohlenstoff) und 666 m2/g (SiO2) erhalten. Das Wachstum der Silbernanopartikel konnte mittels Temperatur abhängiger Röntgenpulverdiffraktometrie beobachtet werden, und es wurde gezeigt, dass ein Wachstum erst während des Karbonisationsprozesses einsetzt. Mittels der HAADF-STEM-Technik wurden die gebildeten Nanopartikel im porösen Kohlenstoff bzw. SiO2 nachgewiesen, dabei liegen die Nanopartikel-durchmesser unterhalb von 5nm. Darüber hinaus konnte eine Vielzahl von neuen Zwillingsmonomeren dargestellt und charakterisiert werden. Darunter finden sich Zirkonium- und Hafnium-haltige Verbindungen, die analog der bekannten Si-Zwillingsmonomere ein ähnliches Polymerisationsverhalten zeigen und aus den resultierenden Hybridmaterialien poröse Oxide mit spezifischen Oberflächen unter 100 m2/g erhalten wurden. Eine Ausnahme bildet hierbei die SBS-Analoge Hafniumverbindung zur Phasenseparation während der Zwillingspolymerisation neigt, ebenso konnte für diese Verbindung kein vollständiger Umsatz erzielt werden. Durch Copolymerisation dieser neuen Zr- und Hf-haltigen Monomeren mit 2,2‘-Spirobi[4H-1,2,2-benzodioxasilin] wurden ZrO2- und HfO2-reiche SiO2-Mischoxide dargestellt. Dabei wurde das thermische Verhalten dieser Mischoxide mittels DSC weiter untersucht und es zeigte sich das ab 1000°C die ZrO2 sowie HfO2-Phasen beginnen zu Kristallisieren. Die so gebildeten hochkristallinen Nanopartikel konnten mittels TEM beobachtet werden. Ein weiteres erhitzen auf über 1200 °C führte dann noch zur Kristallisation der SiO2-Matrix. Ein weiteres Beispiel zur Synthese von oxidische Nanopartikeln mittels Zwillingspolymerisation wurde am ersten Metallocenhaltigen Zwillingsmonomer gezeigt. Dieses war aus der Reaktion von SiCl4 und Ferrocenylmethanol zugänglich. Neben der standardmäßigen Charakterisierung wurde auch die elektrochemischen Eigenschaften hin untersucht und dabei zeigte anders als es zu erwarten war eine Redox-Separation zwischen den einzelnen Ferrocengruppen. Weiterführende spektroelektrochemischen Experimente zeigten, dass diese Aufspaltung durch elektrostatische Abstoßung hervorgerufen wird. Das Zwillingspolymerisationsverhalten wurde zunächst mittels DSC untersucht und dabei konnte bei 210 °C eine exotherme Reaktion beobachtet werden, die mittels TG-MS als Kondensationsreaktion identifiziert wurde. Aufgrund dieser Ergebnisse konnte das Ferrocen-haltige Zwillingsmonomer thermisch polymerisiert werden. HAADF-STEM Abbildungen zeigten den typischen Aufbau eines Zwillingspolymeres, jedoch ist die Anzahl der zu beobachtenden Siliziumdioxidnanocluster geringer als bei bekannten Si-basierten Monomeren. Durch Copolymerisation mit 2,2‘-Spirobi[4H-1,2,2-benzodioxasilin] konnte dieser Nachteil ausgeglichen werden und nach karbonisierung und herauslösen der SiO2-Komponente bzw. Oxidation wird poröser Kohlenstoff (858 m2/g) bzw. Siliziumdioxid (555 m2/g) erhalten. Die Natur der eingebettet Eisenhaltigen Nanopartikel konnte mithilfe von Mössbauerspektroskopie untersucht werden. Dabei wurde im Kohlenstoffmaterial eine Mischung aus Fe2O3 und Fe3C gefunden während im SiO2 aufgrund der oxidierenden Bedingungen, während der Darstellung, von Fe2O3-Nanopartikeln ausgegangen wird. Die durchgeführten Mössbauerexperimente lieferten auch Indizien dafür, dass die gebildeten Nanopartikel sehr klein sind, dies wurde auch mittels HAADF-STEM bestätigt, jedoch kann kein genauer Zahlenwert fehlerfrei angegeben werden. Die geringe Größe spiegelt sich auch im magnetischen Verhalten der porösen Materialien wieder so verhält sich das SiO2 Material superparamagnetisch während der Kohlenstoff paramagnetisch ist. Abschließend konnten Pyrrol-basierte Siliziumalkoxide durch die Reaktion von SiCl4 und den entsprechenden Alkoholen dargestellt werden. Das Zwillingspolymerisation verhalten wurde mittels DSC charakterisiert. Dabei konnten wie schon zuvor beschrieben exotherme Reaktionen detektiert werden und diese liegen deutlich unter den Initiierungstemperaturen der bekannten Zwillingsmonomere (140 °C für N-Methylpyrrol und 93 °C für Pyrrol). Mittels TG-MS konnten auch hier Kondensationsreaktionen identifiziert werden. Daraufhin wurde die Hybridmaterialien aus den thermisch induzierten Polymerisationsversuchen beider Verbindungen untersucht. Es zeigte sich, dass das N-Methyl substituiertes Monomer sich nur in schlechten Ausbeuten polymerisieren lässt während das Pyrrolderivat ausgezeichnete Ausbeuten liefert. Auch die spezifischen Oberflächen sind mit bis zu 633 m2/g beträchtlich höher als mit vergleichbaren und bekannten Zwillingsmonomeren erzielt werden können. Auch zeigen sich beim einfachen Pyrrolbasierten Monomer Unterschiede zwischen thermischer und säure initiierter Zwillingspolymerisation. Während im ersten Fall hauptsächlich das 2-5-Substituierte Polymer erhalten wird kommt es bei säure Initiierung auch zur Bildung einer N-Alkyliertenspezies. Aus den Dargestellten Hybridmaterialien konnten poröse Kohlenstoffe mit Stickstoffgehalten zwischen 5.0-9.1 % erhalten werden. Auch hier zeigte sich das die Kohlenstoffe abgeleitet von dem N-methylierten Pyrrol einen höheren Stickstoffgehalt aufweisen als die aus der unmethylierte Spezies.

Στα πλαίσια της έλλειψης της μελέτης του φαινομένου της ΑΘΝ σε περιφερειακές Ελληνικές πόλεις, η παρούσα διδακτορική διατριβή παρουσιάζει και αναλύει τα αποτελέσματα της μελέτης του φαινομένου της ΑΘΝ σε δύο μικρές πόλεις της περιφέρειας, το Αγρίνιο και τα Ιωάννινα. Στόχος της εργασίας είναι να μελετήσει την ύπαρξη της ΑΘΝ, καθώς και να προσδιορίσει την ένταση και τη μορφή της. Για το σκοπό αυτό ένα δίκτυο αισθητήρων θερμοκρασίας σε συνδυασμό με μετεωρολογικούς σταθμούς αναπτύχθηκε στις δύο πόλεις και θερμοκρασιακά δεδομένα συλλέχθηκαν για το σχηματισμό του θερμικού τους προφίλ. Τα αποτελέσματα δείχνουν έντονη παρουσία του φαινομένου κυρίως κατά τις βραδινές ώρες και ένταση θερμικής νησίδας που φτάνει και τη μέση τιμή των 3.8 οC το μήνα Αύγουστο στο Αγρίνιο ενώ στα Ιωάννινα για την ίδια περίοδο το φαινόμενο έχει πιο ήπια μορφή (1.5 οC). Για την αντιμετώπιση του φαινομένου, την εξοικονόμηση ενέργειας καθώς και τη βελτίωση της θερμικής άνεσης των κτιρίων πόλεων που αντιμετωπίζουν πρόβλημα με την ΑΘΝ, μελετήθηκε η περίπτωση χρήσης υδρόφιλων ενεργειακών υλικών ως επικάλυψη οροφών, για μείωση της ροής θερμότητας από την οροφή με εξατμιστικό δροσισμό καθώς και τα δευτερεύοντα ενεργειακά κέρδη από μια πιθανή εγκατάσταση φωτοβολταϊκών οροφής. Η μελέτη περιλάμβανε την ανάπτυξη πειραματικής διάταξης αεροσήραγγας για τη δοκιμή των υλικών, με προσομοίωση των καιρικών συνθηκών της πόλης κατά του καλοκαιρινούς μήνες, όπου και το φαινόμενο της αστικής θερμικής νησίδας είναι πολύ έντονο, καθώς και ανάπτυξη φωτοβολταϊκών σε ταράτσα πανεπιστημιακού κτιρίου. Τα αποτελέσματα δείχνουν ότι ο εξατμιστικός δροσισμός μπορεί να αποτελέσει μια πολλά υποσχόμενη μέθοδο για την αντιμετώπιση της ΑΘΝ, ενώ η εγκατάσταση φωτοβολταϊκών μπορεί να συνεισφέρει επίσης στην εξοικονόμηση ενέργειας για δροσισμό τους καλοκαιρινούς μήνες, επιπλέον της παραγωγής ενέργειας. / Due to the lack of research on the field of the UHI effect in minor Greek cities, this thesis presents and analyzes the results of studying the UHI phenomenon in two small cities of the Greek province, Agrinio and Ioannina. Our aim was to study the existence of the UHI phenomenon as well as to determine its intensity and its type. In order to achieve that, a network of thermal sensors and meteorological stations was set on the two cities and temperature data were collected in order to define their thermal profile. The results point severe presence of the phenomenon especially during the nocturnal hours while the intensity of the phenomenon reaches up to 3.8 οC during August in Agrinio while in Ioannina at the same period the phenomenon is softer (1.5 οC). To mitigate the problem, save energy and improve the thermal capacity of the urban buildings in cities where the UHI occurs, the use of hydrophilic materials as a layer sheathing the roof was developed, in order to control the thermal flow from the roof by evaporative cooling. Furthermore, secondary energy benefits from a possible photovoltaics roof installation were investigated. Our research included the developing of an experimental set-up of a wind tunnel where sample materials were tested, by simulating the weather conditions of the city during the summer months, exactly the period of the high UHI intensity, as well as the installation of photovoltaics on a terrace of the university. The results indicate that evaporative cooling might be a very promising method in the field of the UHI phenomenon confrontation while the installation of photovoltaics can contribute in power saving for cooling during the summer months, in addition to electricity production.

Metal-organic framework (MOF) compounds as a new class of porous coordination polymers consists of metal ions or clusters linked by organic molecules. They have gained recent interest because of their large surface areas and huge variety of the porous network structures. They exhibit interesting adsorption properties and therefore are potential candidates for various technical applications. In this work, continuous wave (cw) and pulsed electron paramagnetic resonance (EPR) methods such as pulsed electron-nuclear double resonance (ENDOR) and hyperfine sublevel correlation (HYSCORE) spectroscopy are applied to study metal-organic frameworks with respect to different aspects of their properties: The host-guest interactions between Cu2+ ions in [Cu3(btc)2]n (HKUST-1; btc: 1,3,5-benzenetricaboxylate) with adsorbed methanol (CH3OH), 13C enriched carbon monoxide and dioxide (13CO, 13CO2), hydrogen (H2), deuterium (D2) and mixed isotopic HD. In [Cu3(btc)2]n, the Cu2+ ions are connected to binuclear Cu/Cu paddle wheel units. Since the Cu2+ ions in the [Cu3(btc)2]n are antiferromagnetically coupled, the new compound [Cu2.97Zn0.03(btc)2]n is synthesized by isomorphous substitution containing about 1 % paramagnetic Cu/Zn paddle wheel units. The modified Cu/Zn paddle wheel units prove to be a very sensitive probe for the interactions with the adsorbed molecules. Secondly, the exchange interactions of antiferromagnetically coupled Cu/Cu paddle wheel units as well as additional inter-paddle wheel exchange interactions between the Cu/Cu pairs are studied in [Cu2(bdc)2(dabco)]n, a layered MOF with 1,4-benzenedicaboxylate (bdc) as linker and 1,4-diazabicyclo[2.2.2]octane (dabco) acting as pillars between the layers. In comparison to [Cu3(btc)2]n, the additional inter-paddle wheel exchange interactions are much easier disturbed by incorporation of Zn2+ ions into the framework structure. Third, the structural dynamics of the framework is investigated in the compound [Al(OH)(bdc)]n (MIL-53) which was isomorphously substituted by V(III)/V(IV) species. The 51V hyperfine structure revealed to be sensitive to the so-called breathing effect, a flexible structural behaviour upon guest adsorption/desorption or upon thermal treatment. It is shown that the aluminum ions can be substituted by vanadium but the octahedral coordination environment changes slightly to a pseudo-octahedral or a square-pyramidal coordination. Based on the hyperfine interactions between the electron spin and the nuclear spins of the surrounding atoms, structural models can be derived from orientation-selective measurements. In such a way, structural information of materials like powder samples and adsorbate complexes can be obtained which are hardly or even not accessible by other methods.

The chemical element carbon plays a key role in the 21st century. “The new carbon age” is associated with the global warming due to increasing carbon dioxide emissions. The latter are a major consequence of the continued combustion of fossil fuels for energy generation. However, carbon is also one key component to overcome these problems. Especially porous carbon materials are highly attractive for many environmentally relevant applications. These materials provide high specific surface area, high pore volume, thermal/chemical stability, and high electrical conductivity. They are promising candidates for the removal of carbon dioxide or other environmentally relevant gases from exhaust gas mixtures. Furthermore, porous carbons are used in electrochemical energy storage devices (e.g. batteries or electrochemical capacitors). The performance of the materials in these applications depends on their pore structure. Hence, precise control over the pore size and the pore geometry is important to achieve. Besides a high specific surface area (SSA) and a well-defined pore size, pore accessibility must be ensured because the surface must be completely available. If the porous carbons exhibit ink-bottle pores, the high surface area is useless because the guest species do not reach the pore interior. Therefore, carbon materials with hierarchical pore structure are attractive. They combine at least two different pore systems of different size which contribute with their individual advantages. While smaller pores provide large specific surface area, larger pores ensure efficient mass transport. Numerous methods for the targeted synthesis of carbide-derived carbon materials (CDCs) with hierarchical pore architectures were developed within this thesis (Figure 1). CDCs are produced by the extraction of metal- or semi-metal atoms from carbide precursors leading to the formation of a microporous carbon network with high specific surface area. PolyHIPE-CDCs with porosity on three hierarchy levels and total pore volumes as high as 8.5 cm3/g were prepared by a high internal phase emulsion technique. CO2 activation increases the SSA to values above 3100 m2/g. These materials are promising for the filtration of non-polar organic compounds from gas mixtures. CDC nanospheres with diameters below 200 nm were obtained from polycarbosilane-based miniemulsions. They show high capacitance of up to 175 F/g in symmetrical EDLCs in 1 M H2SO4 aqueous electrolyte. Besides such emulsion techniques, the hard-templating concept (also referred to as nanocasting) was presented as an efficient approach for the synthesis of CDC mesofoam powders and meso-macroporous CDC monoliths starting from silica templates and polycarbosilane precursors. As a wide range of pore sizes is approachable, the resulting materials are highly versatile in terms of application. Due to their high nanopore volume, well-defined mesopores and large SSA, they show outstanding properties as electrode materials in EDLCs or in Li-S batteries as well as high and rapid uptake in gas adsorption processes. CDC aerogels were produced by pyrolysis and high-temperature chlorine treatment of cross-linked polycarbosilane aerogels. These materials can be tailored for efficient CO2 adsorption and show outstanding performance in EDLC electrodes at high current densities of up to 100 A/g due to the very short electron diffusion pathways within the aerogel-type pore system. It was further shown that CDCs can be combined with mesopores by the sacrificial template method starting from PMMA particles as the pore-forming material. The use of highly toxic hydrofluoric acid for template removal and large amounts of organic solvents as typical for hard- and soft-templating approaches can be overcome. SSAs and total pore volumes of 2434 m2/g and 2.64 cm3/g are achieved ensuring good performance of PMMA-CDCs in Li-S batteries cathodes. Besides the characterization of CDCs in real energy storage devices and adsorption processes, their use as model substances in energy- and environmentally relevant applications was part of this thesis. The questions “How does it work?” and “What do we need?” must be clearly answered before any material can be tailored under the consideration of economic and ecological perspectives. The high potential of CDCs for this purpose was shown in this thesis. These carbons were used as model substances in combination with nuclear magnetic resonance (NMR) techniques to get a detailed understanding of the adsorption processes on porous carbon surfaces. However, such investigations require the use of model substances with a tailored and well-defined pore structure to clearly differentiate physical states of adsorbed species and to understand fundamental mechanisms. The characterization of the interaction of electrolyte molecules with the carbon surface was performed with solid-state NMR experiments. The materials were also studied in the high-pressure adsorption of 129Xe using an in-situ NMR technique. Both NMR studies enable the analysis of ions or gas atoms adsorbed on the carbon surface on an atomic level and experimentally demonstrate different strength of interaction with pores of variable size and connectivity. In addition, the novel InfraSORP technology was used for the investigation of the thermal response of CDCs and templated carbon and carbide materials during n-butane adsorption. These model systems lead to a more profound understanding of this technique for the rapid characterization of porous materials. The Kroll-Carbon (KC) concept is a highly attractive alternative for the synthesis of well-defined carbons on the large scale. In this technique, the porous materials are produced by the reductive carbochlorination reaction between oxidic nanoparticles and a surrounding carbon matrix. First KC materials were produced with high SSA close to 2000 m2/g and total pore volumes exceeding 3 cm3/g. This method was established with template particles of various dimensions as well as by using various types of oxides (silica, alumina, titania). Hence, porous carbon materials with various textural parameters are approachable. The first generation of KCs is promising for the use in Li-S battery cathodes and as electrode materials in EDLCs.

The present thesis is to be brought into line with the current need for alternative and sustainable approaches toward energy management and materials design. In this context, carbon in particular has become the material of choice in many fields such as energy conversion and storage. Herein, three main topics are covered: 1)An alternative synthesis strategy toward highly porous functional carbons with tunable porosity using ordinary salts as porogen (denoted as “salt templating”) 2)The one-pot synthesis of porous metal nitride containing functional carbon composites 3)The combination of both approaches, enabling the generation of highly porous composites with finely tunable properties All approaches have in common that they are based on the utilization of ionic liquids, salts which are liquid below 100 °C, as precursors. Just recently, ionic liquids were shown to be versatile precursors for the generation of heteroatom-doped carbons since the liquid state and a negligible vapor pressure are highly advantageous properties. However, in most cases the products do not possess any porosity which is essential for many applications. In the first part, “salt templating”, the utilization of salts as diverse and sustainable porogens, is introduced. Exemplarily shown for ionic liquid derived nitrogen- and nitrogen-boron-co-doped carbons, the control of the porosity and morphology on the nanometer scale by salt templating is presented. The studies within this thesis were conducted with the ionic liquids 1-Butyl-3-methyl-pyridinium dicyanamide (Bmp-dca), 1-Ethyl-3-methyl-imidazolium dicyanamide (Emim-dca) and 1 Ethyl 3-methyl-imidazolium tetracyanoborate (Emim-tcb). The materials are generated through thermal treatment of precursor mixtures containing one of the ionic liquids and a porogen salt. By simple removal of the non-carbonizable template salt with water, functional graphitic carbons with pore sizes ranging from micro- to mesoporous and surface areas up to 2000 m2g-1 are obtained. The carbon morphologies, which presumably originate from different onsets of demixing, mainly depend on the nature of the porogen salt whereas the nature of the ionic liquid plays a minor role. Thus, a structural effect of the porogen salt rather than activation can be assumed. This offers an alternative to conventional activation and templating methods, enabling to avoid multiple-step and energy-consuming synthesis pathways as well as employment of hazardous chemicals for the template removal. The composition of the carbons can be altered via the heat-treatment procedure, thus at lower synthesis temperatures rather polymeric carbonaceous materials with a high degree of functional groups and high surface areas are accessible. First results suggest the suitability of the materials for CO2 utilization. In order to further illustrate the potential of ionic liquids as carbon precursors and to expand the class of carbons which can be obtained, the ionic liquid 1-Ethyl-3-methyl-imidazolium thiocyanate (Emim-scn) is introduced for the generation of nitrogen-sulfur-co-doped carbons in combination with the already studied ionic liquids Bmp-dca and Emim-dca. Here, the salt templating approach should also be applicable eventually further illustrating the potential of salt templating, too. In the second part, a one-pot and template-free synthesis approach toward inherently porous metal nitride nanoparticle containing nitrogen-doped carbon composites is presented. Since ionic liquids also offer outstanding solubility properties, the materials can be generated through the carbonization of homogeneous solutions of an ionic liquid acting as nitrogen as well as carbon source and the respective metal precursor. The metal content and surface area are easily tunable via the initial metal precursor amount. Furthermore, it is also possible to synthesize composites with ternary nitride nanoparticles whose composition is adjustable by the metal ratio in the precursor solution. Finally, both approaches are combined into salt templating of the one-pot composites. This opens the way to the one-step synthesis of composites with tunable composition, particle size as well as precisely controllable porosity and morphology. Thereby, common synthesis strategies where the product composition is often negatively affected by the template removal procedure can be avoided. The composites are further shown to be suitable as electrodes for supercapacitors. Here, different properties such as porosity, metal content and particle size are investigated and discussed with respect to their influence on the energy storage performance. Because a variety of ionic liquids, metal precursors and salts can be combined and a simple closed-loop process including salt recycling is imaginable, the approaches present a promising platform toward sustainable materials design. / Die vorliegende Arbeit basiert auf der Notwendigkeit für eine alternative und nachhaltige Energiewirtschaft sowie alternativer Herstellungsmethoden der damit verbundenen Materialien. Hierbei kommt besonders Kohlenstoffen und kohlenstoffbasierten Systemen eine hohe Bedeutung zu. Im Rahmen der Dissertation wurden drei Ansätze verfolgt, die zu der Entwicklung alternativer Strategien zur Herstellung poröser Heteroatom-enthaltender Kohlenstoffe und deren Komposite beitragen. Die Materialien wurden des Weiteren für die CO2 Nutzung sowie Energiespeicherung in Form von Superkondensatoren getestet. Allen Materialien ist gemeinsam, dass sie ausgehend von ionischen Flüssigkeiten, Salze mit einem Schmelzpunkt unterhalb von 100 °C, als Kohlenstoffvorstufe durch Hochtemperaturverfahren hergestellt wurden. Im ersten Teil wird ein alternatives und nachhaltiges Verfahren zur Herstellung hochporöser Stickstoff und Stickstoff-Bor-haltiger Kohlenstoffe vorgestellt. Bei dieser als „Salztemplatierung“ bezeichneten Methode werden herkömmliche Salze als Porogen verwendet. Damit sind sehr hohe Oberflächen erreichbar, die neben der Porengröße und dem Porenvolumen durch die Variation der Salzspezies und Salzmenge einstellbar sind. Dies bietet gegenüber herkömmlichen Templatierungsverfahren den Vorteil, dass das Salz nach erfolgter Karbonisierung der ionischen Flüssigkeit in Anwesenheit der nicht karbonisierbaren Salzspezies einfach mit Wasser auswaschbar ist. Hierbei ist ein Recyclingprozess denkbar. Bei hohen Synthesetemperaturen werden graphitische, bei niedrigen hochfunktionalisierte, polymerartige Produkte erhalten. Letztere erwiesen sich als vielversprechende Materialien für die CO2 Nutzung. Unter Verwendung einer bisher nicht eingesetzten ionische Flüssigkeit konnte weiterhin die Einführung von Schwefel als Heteroatom ermöglicht werden. Im zweiten Teil wird eine Templat-freie Einschrittsynthese von porösen Kompositen aus Metallnitrid Nanopartikeln und Stickstoff-dotiertem Kohlenstoff vorgestellt. Die Materialien werden ausgehend von einer Lösung aus einer ionischen Flüssigkeit und einem Metallvorläufer hergestellt, wobei die ionische Flüssigkeit sowohl als Kohlenstoffvorläufer als auch als Stickstoffquelle für die Metallnitride dient. Der Metallgehalt, das Metallverhältnis in ternären Nitriden und die Oberfläche sind über den Anteil des Metallvorläufers einstellbar. Schließlich werden beide Ansätze zur Salztemplatierung von den Kompositen kombiniert. Dadurch wird die Einschrittsynthese von Kompositen mit einstellbarer Oberfläche, Zusammensetzung, Partikelgröße und Morphologie ermöglicht. Diese Materialien wurden schließlich als Elektroden für Superkondensatoren getestet und der Einfluss verschiedener Parameter auf die Leistungsfähigkeit untersucht. Aufgrund verschiedener Kombinationsmöglichkeiten von ionischen Flüssigkeiten, Metallvorläufern und Salzen, stellen die hier präsentierten Ansätze eine vielversprechende Plattform für die nachhaltige Materialsynthese dar.