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Abstract:
The development of processes for the direct functionalization of short-chain hydrocarbons to higher value chemicals is one of the key challenges in catalysis research. One of the most promising approaches in this regard is the selective alkane oxidation in sulfuric acid/oleum, often associated with the names of Roy A. Periana and Catalytica Incorporated. Most notably, under well-chosen reaction conditions catalytic activities for methane oxidation in the range of large scale industrial processes have been achieved.
Iodine has for the first time been shown to catalyze the transformation of ethane in oleum toward a derivative of ethylene glycol and substantially exceeds the catalytic activity of state-of-the-art Pt-based catalysts. Thermal lability of the product, however, limits the overall production rate.
This thesis further addresses the most pressing technological issue of the “Periana/Catalytica” system: Product separation can be seen as the most severe challenge toward upscaling of this process. Various approaches to isolate methyl bisulfate from the post-reaction mixture, which were investigated within the course of this work, are discussed.
Additionally, the feasibility of “electrifying” said catalytic system on a preparative scale has been evaluated. By means of electrochemistry dilution of the reaction medium with proceeding methane conversion could in principle be avoided which could be highly beneficial in view of the challenging product separation. For this purpose, a high-pressure electrochemical cell has been developed.
Moreover, an innovative mechanochemical and solvent-free approach is introduced that makes use of trichloroisocyanuric acid as a solid reagent for the selective monochlorination of methane. Compared to the purely thermally-driven process the operation temperature is substantially reduced. In this way, the mechanochemical reaction can be carried out under non-corrosive conditions and undesired consecutive transformations of chloromethane are efficiently suppressed.
