Selektive Umwandlung multifunktionaler Biomassesubstrate mit in ionischen Flüssigkeiten stabilisierten Nanopartikelkatalysatorsystemen (2013)

Due to the increasing demand for energy carriers and fossil resources, as well as the rising anthropogenic CO2 emissions society faces the challenge of identifying new sustainable resources. In this context, biomass represents an attractive alternative because of its sustainability and its abundance. The catalytic conversion of biomass gives access to various chemical intermediates and potential fuels. As biomass exhibit many functional groups, generally it is converted into so-called platform molecules, which can be transformed to valuable chemicals by de- and refunctionalisation. This transformation requires new catalyst design as well was new process strategies to enable an efficient and selective access to the desired products. This thesis describes a new range of products from fufuralacetone accessible via multifunctional catalytic systems. At first, the potential products from furfuralacetone were identified and a suitable catalytic system was evaluated. Especially, in ionic liquids (IL) stabilised transition metal nanoparticles showed very promising activity and selectivity. It was possible to synthesis four different hydrogenation products starting from furfuralacetone selectively by employing various IL-stabilised nanoparticles. Particularly ruthenium nanoparticles stabilised in 1- dodecyl-3-methylimidazolium bis(trifluoromethansulfonyl)imid Ru@[C12MIM][NTf2] exhibited high activity and selectivity in the conversion of furfuralacetone to the fully hydrogenated product 2-(4-tatrahydrofuryl)-butanol. Furthermore, recycling experiments of Ru@[C12MIM][NTf2] showed no loss of reactivity or selectivity over fife cycles. In comparison to classic homogeneous and heterogeneous rutheniums catalyst the nanoparticles systems were much more reactive and tolerant towards biomass substrates and were able to hydrogenate various bio-based molecules. Moreover, by immobilising the nanoparticles on a solid support it was possible to apply the catalyst in continuous hydrogenation of furfuralacetone in supercritcial CO2. Modification of the nanoparticle systems was possible by functionalisation of the ionic liquids with sulfonic groups. The introduction of an acidic group lead to multifunctional catalytic systems with a redoxactive and an acidic site. These catalytic systems were very active in the hydrogenation and dehydration of 4-(2-tetrahydrofuryl)-butanol to 2-butyltetrahydrofuran and the C8-OL products 1-octanol and 1,1-dioctylether. By varying the ionic liquid and the reaction conditions it was possible to tune the selectivity to the desired product with a high selectivity towards secondary alcohols. Only traces of the fully hydrogenated product octane were observed. The combination of the hydrogenation step with the following hydrogenation and dehydration in a two step-one pot reaction gave access to the valuable C8-OL products with a selectivity of 93%. No purification in between was necessary. Furthermore, by immobilising the nanoparticles on acidic functionalised support it was even possible to recycle the catalytic system without loss in activity and selectivity. To conclude, the results of this thesis demonstrate that sensible catalyst and process design enables the synthesis of various products starting from the platform molecule fufuralaceton. The application of multifunctional ruthenium nanoparticles systems give access to valuable intermediates and potential fuels, which were not accessible before or only with poor selectivity.