(234e) A First Way of Managing Humin Formation

In finding new ways of using a sustainable feedstock for high value chemicals, lignocellulosic biomass emerged as an excellent source. First plants for the industrial chemically catalyzed production of levulinic acid from biomass have been launched. However, a significant amount, between 40 and 60%, of widely branched polymers are produced. Those polymers, called humins, are dark colored, solid and insoluble in common solvents. So far the humins are solely used as a source of energy by being burnt directly on-site. Due to the insoluble and sticky character of the humins, the blockage of the reactor has to be avoided in a costly manner. Consequently, humins are not desired in in the process and lower both the E-factor and the profit of the process. Therefore it is of high interest to find a way to either minimize the humin formation in the process or to use the humins for the production of a new value added material. To obtain this, the kinetics, the thermodynamics and the mechanism of the humin formation as well as the structure of the humins are fundamental to know.

The focus of our research is on the extensive description of the humin formation with the use of suitable analytical methods, a deep analysis of the results and a simulation of the combined knowledge including results found in literature. The experiments are crucial for the analysis. They are planned with â??Design of Experimentsâ? (DoE) and cover all known significant factors of the humin formation. A variety of analytical methods, including ATR mIR spectroscopy and elemental analysis, were used to gain insight into the structure of the humin samples. The results were combined with data from literature and give insights into the character of the mechanism, kinetic and thermodynamic of the humin formation and the structure of the product depending on the reaction conditions and sample treatment. The analysis of the results gained in scale by an extended use of van Krevelen diagrams. Therefore a new method was developed to obtain mechanistic information from the analytics. The method can find evidence for a certain mechanism or combination of more mechanisms that lead to one polymer. All information together was fed in a simulation that can be used as tool to control humin formation.

The work covers not only the control of the humin formation in amount but also a prediction of the structure and handling suggestions.