Die vorliegende Arbeit beschäftigt sich mit der Synthese von Pincer-Ligandenvor-läufern mit fluorierten Alkylketten –(CH2)2Rf6 (Rf6 = C6F13) an Sauerstoff- bzw. Phosphorhaftatomen. Darüber hinaus stehen die Bildung hochfluorierter Lithium-, Palladium-, Ruthenium- sowie Aluminium-Pincer-Komplexe und die Reaktivitäts-studien für diese neuartigen Komplexe im Fokus. Für vergleichende Untersuchungen war ebenso die Synthese der analogen, nicht fluorierten Verbindungen von Interesse. Eine Mischung aus in situ hergestelltem (NC5H3)-1,3-(CH2P((CH2)2(CF2)5CF3)2)2 (13) und [Ru(2Me-C3H4)2(cod)] kann die Dehydrogenierung von Cyclooctan bei vergleichsweise niedrigen Temperaturen von 80 °C katalysieren. Interessant ist die je nach Lösungsmittel unterschiedliche Produktbildung. Die Lithium- und Aluminiumkomplexe [Li(C6H3-2,6-(CH2O(CH2)2(CF2)5CF3)2)] (21), [Li(C6H3 2,6 (CH2OCH3)2)] (22), [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)(CH3)2] (28), [Al((C6H3)-2,6-(CH2OCH3)2)I2] (29), [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)I2] (31) wurden erfolgreich synthetisiert und charakterisiert. Mittels [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)I2] (31) konnten diverse aromatische Verbindungen wie Benzol, Toluol oder Pentafluorbenzol dehydrogenierend gekuppelt werden. Weiterhin wurden die Palladiumkomplexe [Pd(Cl)((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)] (34) und [Pd(NCCH3)((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)][PF6] (36), [Pd(Cl)((C6H3)-2,6-(CH2OCH3)2] (37) und [Pd(NCCH3)((C6H3)-2,6-(CH2OCH3)2][PF6] (38) hergestellt und charakterisiert. / The current thesis is concerned with the syntheses of pincer ligand precursors with fluorinated alkyl chains –(CH2)2Rf6 (Rf6 = C6F13), the so called „ponytails“, at oxygen or phosphorous donor atoms. Furthermore, this work focuses on the formation of highly fluorinated lithium, palladium, ruthenium or alumina pincer complexes and considering reactivity studies of these novel compounds. For comparative investigations the syntheses of the analog non-fluorinated compounds was of great interest. A mixture of in situ synthesized (NC5H3)-1,3-(CH2P((CH2)2(CF2)5CF3)2)2 (13) and [Ru(2Me-C3H4)2(cod)] catalyses the dehydrogenation of cyclooctane at relatively low temperatures of 80 °C. Depending on the used solvent cyclooctene or cyclooctatriene can be received as the single product, respectively. The lithium and alumina complexes [Li(C6H3-2,6-(CH2O(CH2)2(CF2)5CF3)2)] (21), [Li(C6H3 2,6 (CH2OCH3)2)] (22), [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)(CH3)2] (28), [Al((C6H3)-2,6-(CH2OCH3)2)I2] (29), and [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)I2] (31) were synthesized and characterized succesfully. With the complex [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)I2] (31) a diversity of aromatic compounds like benzene, toluene or pentafluorobenzene can be coupled after dehydrogenation. Moreover, the palladium complexes [Pd(Cl)((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)] (34), [Pd(NCCH3)((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)][PF6] (36), [Pd(Cl)((C6H3)-2,6-(CH2OCH3)2] (37) and [Pd(NCCH3)((C6H3)-2,6-(CH2OCH3)2][PF6] (38) were synthesized and characterized.

<p>The increase in shale gas exploitation has motivated the studies towards new processes for converting light alkanes into higher valuable chemicals, including fuels. The works in this dissertation focuses on two processes: propane dehydrogenation and ethylene oligomerization. The former involves the conversion of propane into propylene and hydrogen, while the latter converts light alkenes into higher molecular weight products, such as butylene and hexene. </p> <p>The thesis project focuses on understanding the effect of geometric effects of Pt alloy catalysts for propane dehydrogenation and the methodologies for their characterization. Pt-Co bimetallic catalysts were synthesized with increasing Co loadings, characterized and evaluated for its propane dehydrogenation performance. In-situ synchrotron X-Ray Powder Diffraction (XRD) and X-Ray Absorption (XAS) were used to identify and differentiate between the intermetallic compound phases in the nanoparticle surface and core. Difference spectra between oxidized and reduced catalysts suggested that, despite the increase in Co loading, the catalytic surface remained the same, Pt₃Co in a Au₃Cu structure, while the core became richer in Co, changing from a monometallic Pt fcc core at the lowest Co loading to a PtCo phase in a AuCu structure at the highest loading. Co^II single sites were also observed on the surface, due to non-reduced Co species. The catalytic performance towards propane dehydrogenation reinforced this structure, as propylene selectivity was around 96% for all catalysts, albeit the difference in composition. The Turnover Rate (TOR) of these catalysts was also similar to that of monometallic Pt catalysts, around 0.9 s^-1, suggesting Pt was the active site, while Co atoms behaved as non-active, despite both atoms being active in their monometallic counterparts.</p> <p>In the second project, a single site Co^II catalyst supported on SiO₂ was evaluated for ethylene oligomerization activity. The catalyst was synthesized, evaluated for propane dehydrogenation, propylene hydrogenation and ethylene oligomerization activities and characterized <i>in-situ</i> by XAS and EXAFS and H₂/D₂ exchange experiments. The catalysts have shown negligible conversion at 250^oC for ethylene oligomerization, while a benchmark Ni/SiO₂ catalyst had about 20% conversion and TOR of 2.3x10^-1 s^-1. However, as the temperature increased to above 300^oC, ethylene conversion increased significantly, reaching about 98% above 425^oC. <i>In-situ</i> XANES and EXAFS characterization suggested that H₂ uptake under pure H₂ increased in about two-fold from 200^oC to 500^oC, due to the loss of coordination of Co-O bonds and formation of Co-H bonds. This was further confirmed by H₂/D₂ experiments with a two-fold increase in HD formation per mole of Co. <i>In-situ</i> XAS characterization was also performed with pure C­₂H₄ at 200^oC showed a similar trend in Co-O bond loss, suggesting the formation of Co-alkyl, similarly to that of Co-H. The <i>in-situ</i> XANES spectra showed that the oxidation state remained stable as a Co²⁺ despite the change in the coordination environment, suggesting that the reactions occurs through a non-redox mechanism. These combined results allowed the proposition of a reaction pathway for dehydrogenation and oligomerization reactions, which undergo a similar reaction intermediate, a Metal-alkyl or Metal-Hydride intermediates, activating C-H bonds at high temperatures.</p>

<p>The present work is focused on the synthesis of small-scale (modular processes) to produce olefins from light alkane resources in shale gas.</p> <p>Olefins, which are widely used to produce important chemicals and everyday consumer products, can be produced from light alkanes - ethane, propane, butanes etc. Shale gas is comprised of light alkanes in significant proportion; and is available in abundance. Meanwhile, shale gas wells are small sized in nature and are distributed over many different areas or regions. In this regard, using shale gas as raw material for olefin production would require expensive transportation infrastructure to move the gas from the wells or local gas gathering stations to large central processing facilities. This is because existing technologies for natural gas conversions are particularly suited for large-scale processing. One possible way to take advantage of the abundance of shale resource for olefins production is to place small-sized or modular processing plants at the well sites or local gas gathering stations.</p> <p>In this work, new process concepts are synthesized and studied towards developing simple technologies for on-site and modular processing of light alkane resources in shale gas for olefin production. Replacing steam with methane as diluent in conventional thermal cracking processes is proposed to eliminate front-end separation of methane from the shale gas processing scheme. Results from modeling studies showed that this is a promising approach. To eliminate the huge firebox volume associated with thermal cracking furnaces and allow for a compact cracking reactor system, the use of electricity to supply heat to the cracking reactor is considered. Synthesis efforts led to the development of two electrically powered reactor configurations that have improved energy efficiency and reduced carbon footprints over and compare to conventional thermal cracking furnace configurations.</p> <p>The ideas and results in the present work are radical in nature and could lead to a transformation in the utilization of light alkanes, natural gas and shale resources for the commercial production of fuels and chemicals.</p>