This thesis deals with the development and design of technical laboratory plants to perform catalytic urea synthesis and levulinic acid hydrogenation. The starting point is a novel catalytic system that enables the effective production of urea starting from carbon monoxide or carbon dioxide as the C1 building block via the intermediate formamide. For the hydrogenation of organic carboxylic acids, and in particular bio-based levulinic acid, a tailor-made ruthenium-triphos catalyst was used, which because of its unique properties, enables this extremely demanding chemical transformation. Based on previous fundamental catalysis research on small scale, systematic optimization studies were carried out with the aim of maximizing the product yields and catalyst recycling options in the translation process. Within the scope of this thesis, the specific requirements for the plants, the selection of suitable components and precise control of the process parameters were addressed in detail. Chapter 2.1 discusses the novel possibility to produce urea and the subsequent translation to a mini plant. The focus was on the central reaction pathway for urea synthesis starting from formamide. The reaction parameters temperature, time, as well as the amounts of reagents used were investigated on a larger scale at a laboratory plant tailored for two reaction pathways, eventually allowing to determine the optimal process conditions for maximum product yield. Chapter 2.2 deals with the challenge to establish a complete value chain starting from biomass via the platform chemical levulinic acid to various valuable consumer products. The hydrogenation of levulinic acid, which is in the focus of this thesis, was transferred to a larger scale at a tailored plant. To optimize the product yields of this process, the complex interaction of reaction parameters time, hydrogen pressure, temperature, as well as substrate and catalyst amounts were investigated. The levulinic acid produced in the biorefinery of the Institute of Applied Process Engineering at RWTH Aachen University with a purity of approximately 75wt% was successfully converted directly into γ-valerolactone, 1,4-pentanediol, and 2-methyltetrahydrofuran. Finally, a catalyst immobilization concept was developed that can be used in the future for the continuous hydrogenation of levulinic acid in flow reactors.
Pascal Albrecht (Wed,) studied this question.