Carolin Rieg

Utrecht University
Advanced characterization methods for coke deposits on Ni-Mo/Al2O3 and Ni/Al2O3 extrudates for the catalytic upgrading of fast pyrolysis bio-oil

Fast pyrolysis of biomass produces biomass-based pyrolysis oil, a promising feedstock for sustainable transportation fuels and chemicals. However, its stabilization remains a major challenge due to coke formation, which leads to catalyst deactivation and reduced process efficiency. A deeper understanding of coke formation is essential for developing more resilient catalysts and optimizing bio-oil upgrading strategies. Coke formation on sulfidized Ni-Mo/Al2O3 and Ni/Al2O3 trilobe catalyst extrudates during bio-oil stabilization is investigated using a combination of ex-situ and in-situ techniques to analyze coke deposition, its location, composition, and evolution under reaction conditions. Ex-situ methods, including confocal fluorescence microscopy, Raman spectroscopy, and thermogravimetric analysis, provide detailed characterization of coke deposits. In addition, operando Raman spectroscopy was applied to monitor bio-oil conversion and coke formation in real-time, offering dynamic insights that complement the ex-situ data. This integrated approach enhances the understanding of catalyst deactivation mechanisms and the factors influencing coke accumulation. The findings contribute to the development of more effective catalysts and process strategies for bio-oil upgrading, supporting the advancement of biomass conversion technologies toward more efficient and sustainable fuel production.


Carolin Rieg is a Postdoctoral Researcher in the Inorganic Chemistry and Catalysis Group at Utrecht University since 2023. She earned her Ph.D. from the University of Stuttgart in 2022, where she investigated the accessibility and acidity of acid sites in zeolites and mesoporous materials using solid-state NMR spectroscopy. In her postdoctoral research, she focuses on catalyst deactivation of hydrodeoxygenation catalysts during the upgrading of biomass-based pyrolysis oils.