1. Catalytic hydro(deoxy)genation of furfural and modelling of its reaction kinetics : dissertationRok Šivec, 2024, doktorska disertacija Opis: In recent decades, there has been a growing interest in producing biofuels and biochemicals from renewable sources. Furfural stands as one of the ligno(hemi)cellulosic biomass derived platform chemical, which can be transformed into numerous value-added products.
The goal of this PhD was to systematically study hydrotreatment reactions of furfural under varying operating conditions and to gain insights into the reaction mechanism and kinetics. An extensive experimental and computational study of hydrogenation, hydrodeoxygenation, oligomerisation and etherification of furfural in a three-phase batch reactor was performed. The goals were divided into three consecutive objectives.
In the first part, hydrotreatment of furfural over Pd/C catalyst under various reaction conditions, including the solvent selection (solventless conditions, tetrahydrofuran, isopropanol), atmosphere (nitrogen, hydrogen), temperature (100–200 °C), pressure (25–75 bar) and stirring speed, was studied. A reaction pathway network and a micro-kinetic model were developed, incorporating thermodynamics (hydrogen solubility), mass transfer, adsorption, desorption, and surface reactions. These phenomena and their contribution to the surface coverages, TOF’s and global reaction rates were studied. The hydrogen presence on the catalyst surface was found to influence the main reaction pathway, leading to ring, aldehyde group or full hydrogenation.
In the second part, various monometallic catalysts (Pd/C, Pt/C, Re/C, Ru/C, Rh/C, Ni/C, Cu/C) were tested at 100 -200 °C with 60 bar of hydrogen and tetrahydrofuran as solvent. A generalized reaction pathway network was developed. H2 temperature-programmed reduction (H2-TPR) and CO temperature-programmed desorption (CO-TPD) were conducted, and a regression analysis of the results was subsequently performed by numerical modelling and optimisation. The obtained adsorption and desorption kinetic parameters for active metallic sites were further used in a generalized micro-kinetic model, applicable to all tested catalysts. Pd/C exhibited high activity and non-selective hydrogenation of furfural, while other catalysts showed selective aldehyde group hydrogenation followed by deoxygenation, consistent with density functional theory (DFT) calculations. Ru/C uniquely produced 2 methyltetrahydrofuran and ring-opening products at 200 °C. In silico optimization of reaction conditions for promising catalysts ((Pd/C, Pt/C, Re/C, Ni/C) aimed to maximize the yield of the target product.
In the third part, the influence of support on catalytic activity was studied. Hydrotreatment of furfural over Pd/Al2O3, Pd/SiO2, Ru/Al2O3, Ru/SiO2, Ni/Al2O3, and Ni/SiO2 was performed between 150 - 200 °C, using 60 bar of hydrogen and tetrahydrofuran as solvent. The strength and rate of adsorption and desorption to/from acidic, metallic and interface site structures were determined, using H2-TPR, CO-TPD and NH3-TPD and subsequent regression analysis of the results by numerical modelling and optimisation. The resulting parameters were sequentially used in the generalized micro-kinetic model to quantify the contribution of the active metal (Ni, Pd, or Ru), support (Al2O3 or SiO2), interphase sites and their relationship on catalyst activity and selectivity. Evaluation of morphological and structural characteristics, adsorption/desorption and intrinsic reaction kinetics has indicated that the coverage of acidic sites (on alumina or silica) facilitated yielding ring hydrogenation and inhibited deoxygenation, decarbonylation and cyclic compound opening. The rates for aromatics or aldehyde functional groups were, nonetheless, affected in a different order.
The used and developed methods and findings of this PhD offer useful guidelines for transforming furfural into high-value chemicals through catalytic hydrotreatment, with significant implications for future research and industrial applications.
Ključne besede: lignocellulosic biomass, furfural, catalytic hydrogenation, micro-kinetic mass transfer model, reaction kinetics, first-principle methods, furfuryl alcohol, tetrahydrofurfuryl alcoholv, dissertations
Objavljeno v RUNG: 08.11.2024; Ogledov: 272; Prenosov: 4
 Celotno besedilo (9,22 MB) |
2. Gaia22dkvLb : a microlensing planet potentially accessible to radial-velocity characterizationZexuan Wu, Subo Dong, Tuan Yi, Zhuokai Liu, Kareem El-Badry, Andrew Gould, Łukasz Wyrzykowski, K. A. Rybicki, Mateusz Bronikowski, 2024, izvirni znanstveni članek Opis: We report discovering an exoplanet from following up a microlensing event alerted by Gaia. The event Gaia22dkv is toward a disk source rather than the traditional bulge microlensing fields. Our primary analysis yields a Jovian planet with M_p = 0.59 (+0.15, -0.05) M_J at a projected orbital separation r_perpendicular = 1.4 (+0.8, -0.3) au, and the host is a ∼1.1 M⊙ turnoff star at ∼1.3 kpc. At r' ~= 14, the host is far brighter than any previously discovered microlensing planet host, opening up the opportunity to test the microlensing model with radial velocity (RV) observations. RV data can be used to measure the planet's orbital period and eccentricity, and they also enable searching for inner planets of the microlensing cold Jupiter, as expected from the "inner–outer correlation" inferred from Kepler and RV discoveries. Furthermore, we show that Gaia astrometric microlensing will not only allow precise measurements of its angular Einstein radius θ_E but also directly measure the microlens parallax vector and unambiguously break a geometric light-curve degeneracy, leading to the definitive characterization of the lens system.
Ključne besede: gravitational microlensing exoplanet detection, planetary astrophysics, astrophysics of galaxies, instrumentation astrophysics, methods for astrophysics, solar astrophysics, stellar astrophysics
Objavljeno v RUNG: 23.08.2024; Ogledov: 673; Prenosov: 8
Celotno besedilo (5,11 MB)
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6. Protein quality control for improved data reproducibility and reliabilityKim Remans, Ario De Marco, Nick Berrow, Mario Lebendiker, Maria Garcia-Alai, Stefan Knauer, Andre Matagne, Anne Perret, Stephan Uebel, Bertrand Raynal, 2022, objavljeni povzetek znanstvenega prispevka na konferenci Ključne besede: protein quality, evaluation assays, biophysical methods
Objavljeno v RUNG: 13.04.2023; Ogledov: 1584; Prenosov: 0
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