39 KJEMI 6 2025 Disputaser ved Institutt for kjemisk prosessteknologi ved NTNU i 2025 Petter Tingelstad Date: 11th of April PhD thesis: From Biomass to Refinery-Ready Bio-Crude: Biomass Pyrolysis with Vapor Phase Upgrading Trial lecture: Processes and catalysts for direct and multistep conversion of CO2-rich syngas to SAF (Sustainable Aviation Fuel) Assessment Committee • First opponent: Professor Anker Degn Jensen, CHEC Research Centre, Denmark • Second opponent: Professor David Kubicka, University of Chemistry and Technology Prague, the Czech Republic • Chair of the committee: Professor Edd Anders Blekkan, Department of Chemical Engineering, NTNU Supervisors • Main supervisor: Professor De Chen, Department of Chemical Engineering, NTNU • Co-supervisor: Dr. Kumar Rajan Rout, Quantafuel Summary of thesis Biomass pyrolysis presents a promising alternative to fossil fuels for aviation fuel production. However, a major challenge lies in the high oxygen content of the resulting bio-oil and the significant carbon loss to the aqueous phase. Vapor-phase upgrading offers an effective strategy to mitigate these issues by converting water-soluble oxygenates into higher-carbon, oil-soluble molecules with reduced oxygen content. This process, primarily driven by ketonization and condensation reactions, enhances the bio-oil’s composition, improving its suitability for fuel applications. This thesis investigates the role of catalytic vapor-phase upgrading catalysts through four distinct studies employing different approaches. The ketonization activity of titanium-group metal oxides was analyzed, identifying ZrO2 as the most active but least stable catalyst, while TiO2 demonstrated high activity and superior stability. In-situ DRIFTS studies revealed reversible deactivation due to the accumulation of inactive bidentate carboxylates. The deposition of metal clusters significantly enhanced ketonization, aldol-condensation, and Michael- addition activities by generating new active sites at the metal particle perimeters. A volcano-type relationship between metal-(C,H,O) binding energy and activity was established, with Ni emerging as the most active metal. A combined experimental and computational approach elucidated the ketonization mechanism, identifying C-H bond scission at perimeter sites as the ratedetermining step at temperatures above 573 K. Rational catalyst design, guided by the volcano-type relationship, led to the synthesis of bimetallic CuFe/TiO2 catalysts. Computational studies determined that Cu4Fe/TiO2 exhibited the highest ketonization activity, with metal-C binding energy comparable to Ni. CO DRIFTS measurements indicated that a new bimetalilic CuFe alloy is formed, which has a characteristic signal at a lower wavelength than pure Cu and Fe. TiO2- and Al2O3-based catalysts were employed as ex-situ vapor phase upgrading catalysts in a pyrolysis rig, with TiO2-based catalysts outperforming Al2O3. Among these, Ru/TiO2 demonstrated the highest upgrading efficiency, while (Co+Pt)/TiO2 optimized hydrogenation and carbon coupling, improving process performance. Sorption-enhanced reforming enabled in-situ hydrogen production. Techno-economic analysis identified (Co+Pt)/TiO2 as the most cost-effective catalyst, achieving a minimum fuel selling price of 1.6 $ l−1. The KinCat-Py process showed strong potential for sustainable biofuel production, highlighting the need for further optimization toward commercialization. This work establishes a foundation for future research on bifunctional metaldeposited TiO2 catalysts, emphasizing the importance of engineering metal particle sizes to enhance perimeter site concentration. The methodologies applied in thermodynamic modeling and rational catalyst design are broadly applicable to various catalytic processes.
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