Catalytic multistep hydrogenation and hydrogenolysis reactions for the utilization of renewable carbon resources

• Main Author: Vom Stein, Thorsten
• Other Authors: Leitner, Walter
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Publikationsserver der RWTH Aachen University 2014
• Subjects: info:eu-repo/classification/ddc/540; Katalyse; Katalytische Hydrierung; Lignin; Chemie; nachhaltige Rohstoffe; Kohlendioxid Reduktion; catalytic hydrogenation; catalytic bond cleavage; Carbonic acid
• Online Access: https://publications.rwth-aachen.de/record/459448; https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-145356%22

The present thesis deals with the development of novel homogeneous catalysts for the chemical valorization of renewable carbon resources such as biomass and carbon dioxide. Along these lines, chapter 1 outlines the challenges and chances of homogeneous catalysis in implementing these renewables carbon resources as feedstock for the production of commodity chemicals and fuels. Within this framework, chapter 2 deals with the development and mechanistic understanding of a new well-defined hydrogenation catalyst [Ru(Triphos)TMM] I-1 (TMM = Trimethylenemethane, Triphos = 1,1,1 -Tris(diphenylphosphinomethyl)ethane). This easily accessible precursor is able to activate molecular hydrogen to give access to a neutral Ruthenium dihydride complex [H2Ru(Triphos)S] in absence of acid or a cationic Ruthenium hydride [HRu(Triphos)(H2)S]+ species in presence of acidic co-catalyst (S = solvent, substrate). This tunable activation results in a broad substrate scope and therefore virtually any carboxylic and carbonic acid derivative could be hydrogenated to afford the corresponding alcohol and amine products with high conversion and selectivity. In view of the targeted application of this system to the conversion of renewable carbon feedstock, this versatile reactivity was exploited in the first direct homogeneous hydrogenation of CO2 to methanol and amino acids to amino alcohols. Furthermore this catalytic system was successfully applied in the first reductive N-methylation of aryl amines employing hydrogen and CO2 as C1 synthon. Chapter 3 deals with the development new catalytic systems for the depolymerization of lignin, which is one of the three main constituents of lignocellulosic plant materials and represents the most abundant renewable source for aromatic building blocks. Initially a model based approach was chosen, in which potential catalytic systems were tested in the transfer hydrogenolytic cleavage of model compounds mimicking the structural motif of the predominant beta-O-4 linkage in lignin. In this way, complex ...