1. Photoelectrochemical conversion of biomass alcohols using in-situ Sn-doped ▫$\alpha-Fe_2O_3$▫ thin filmsManel Machreki, Artem Badasyan, Dušan Žigon, Georgi Tyuliev, Saim Emin, 2025, original scientific article Abstract: Transformation of biomass into value-added chemicals and fuels is considered an upcycling process that is beneficial to resource utilization. In this study, we used a photoelectrochemical (PEC) approach for selective oxidation of propane-1,2,3-triol to dihydroxyacetone (DHA) with high efficiency and selectivity (99%) using Sn-doped -Fe2O3 (Sn:-Fe2O3) thin films with intrinsic oxygen vacancies (OVs). DHA is an essential compound utilized in the cosmetic industry. In a similar manner, we conducted the first study of the PEC oxidation of 4-hydroxy-3-methoxybenzyl alcohol under visible light. A kinetic model has been formulated and solved to find the time-dependent generation of the products. Electrochemical impedance analyses and PEC experiments demonstrated a correlation between the concentration of molecules and the catalytic performance of Sn:-Fe2O3. Studies using scavengers indicate that the photogenerated holes (h+), singlet oxygen (1O2), hydroxyl radicals (•OH), and superoxide radicals (•O2–) play key roles in achieving high PEC activity. This work provided a new perspective on designing efficient PEC systems for biomass conversion into energy and value-added chemicals.
Keywords: Sn-doped alpha-Fe2O3, oxygen vacancies, photoelectrochemical oxidation, propane-1, 2, 3-triol, 4-hydroxy-3-methoxybenzyl alcohol
Published in RUNG: 08.01.2025; Views: 159; Downloads: 3
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2. Catalytic hydro(deoxy)genation of furfural and modelling of its reaction kinetics : dissertationRok Šivec, 2024, doctoral dissertation Abstract: 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.
Keywords: lignocellulosic biomass, furfural, catalytic hydrogenation, micro-kinetic mass transfer model, reaction kinetics, first-principle methods, furfuryl alcohol, tetrahydrofurfuryl alcoholv, dissertations
Published in RUNG: 08.11.2024; Views: 467; Downloads: 7
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3. Chemical composition of apple cider : a comparative study of Norwegian and French cidersIngunn Ovsthus, Mitja Martelanc, Tatjana Radovanović Vukajlović, Marko Lesica, Lorena Butinar, Branka Mozetič Vodopivec, Guillaume Antalick, 2024, published scientific conference contribution Abstract: Norwegian apple ciders have recently gained attention at the levels of international competitiveness. Accordingly, a comparative study on the chemical composition of selected Norwegian and French apple ciders was conducted to gain knowledge on what ubiquitous chemical parameters make the Norwegian ciders different from ciders from well-established producing regions. A total of 43 ciders, 24 Norwegian and 19 French, in the category of acidic dominant ciders, were included in the study. Ethanol, individual sugars and organic acids, pH, total phenols, aroma compounds including esters, C6-alcohols, volatile phenols and terpenoids, were analysed. Norwegian ciders showed higher contents in ethanol, malic and citric acids, whereas total phenols, pH, glucose, and fructose were higher in French counterparts. Regarding the aromatic profile, no significant differences were observed for C6-alcohols. In contrast, differences were more expressed in the case of esters and volatile phenols. Norwegian ciders were characterised by higher average concentration for all the groups of esters, with the most important differences measured for higher alcohol acetates. Norwegian ciders also displayed higher contents of 4-vinylphenol and 4-vinylguaiacol while French ciders contained substantially higher levels of 4-ethylphenol and 4-ethylguaiacol. These results are in mutual correlation with the empirical observation reporting Norwegian apple ciders as more acidic, alcoholic and with lighter body but fruitier profile. Whereas French ciders are often perceived with more structure and animalistic profile.
Keywords: alcohol, acidity, total phenols, aroma-compounds, apple cider
Published in RUNG: 25.03.2024; Views: 2019; Downloads: 6
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4. Oxygen vacancies engineering in metal oxide nanomaterials for efficient photo-electrocatalytic degradation of organic pollutants and chemical transformations : dissertationManel Machreki, 2022, doctoral dissertation Keywords: titanium dioxide nanotubes, hematite, oxygen vacancies, photoelectrochemical degradation of dye, ibuprofen, chemical transformation, glycerol, vanillyl alcohol, dissertations
Published in RUNG: 01.03.2023; Views: 2907; Downloads: 57
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5. Characterization of bacterial cellulose films combined with chitosan and polyvinyl alcohol: Evaluation of mechanical and barrier propertiesPatricia Cazón, Gonzalo Velazquez, Manuel Vazquez, 2019, original scientific article Abstract: Bacterial cellulose (BC) produced by Komagataeibacter xylinus is a biomaterial with a unique three-dimensional structure. To improve the mechanical properties and reinforce the BC films, they were immersed in polyvinyl alcohol (0–4%) and chitosan (0–1%) baths. Moisture content, mechanical properties and water vapour perme- ability were measured to assess the effect of polyvinyl alcohol and chitosan. The morphology, optical, structural and thermal properties were evaluated by scanning electron microscopy, spectral analysis, thermogravimetry and differential scanning calorimetry. Results showed that moisture content was significantly affected by the chitosan presence. Tensile strength values in the 20.76–41.65 MPa range were similar to those of synthetic polymer films. Percentage of elongation ranged from 2.28 to 21.82% and Young's modulus ranged from 1043.88 to 2247.82 MPa. The water vapour permeability (1.47×10−11–3.40×10−11 g/m s Pa) decreased with the addition of polyvinyl alcohol. The developed films own UV light barrier properties and optimal visual appearance.
Keywords: Films, Bacterial cellulose, Water vapor permeability, Chitosan, Polyvinyl alcohol, UV protection
Published in RUNG: 14.12.2020; Views: 3240; Downloads: 0
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6. Regenerated cellulose films with chitosan and polyvinyl alcohol: Effect of the moisture content on the barrier, mechanical and optical propertiesPatricia Cazón, Manuel Vazquez, Gonzalo Velazquez, 2020, original scientific article Abstract: The aim of this research was to evaluate the effect of moisture content on the mechanical, barrier and optical properties of films obtained from regenerated cellulose with chitosan and polyvinyl alcohol equilibrated at several relative humidity conditions. The experimental moisture adsorption isotherms were fitted using the Guggenheim-Anderson-DeBoer model. The adsorption isotherm showed a typical type II sigmoidal shape. The highest moisture content (27.53 %) was obtained at a water activity of 0.9. The water vapour permeability values increased up to 6.34·10−11 g/ m s Pa as the moisture content of the films increased. Tensile strength, percentage of elongation, Young’s modulus, burst strength and distance to burst showed a significant plasticizing effect of the water molecules. Results suggest that interactions between film components and water molecules decrease the transmittance in the UV region and the transparency. Consequently, water molecules improve the UV-barrier properties of the films and increasing the opacity.
Keywords: Adsorption isotherms, Plasticization, Regenerated cellulose, Chitosan, Polyvinyl alcohol, Water vapour permeability, Moisture content
Published in RUNG: 09.12.2020; Views: 3763; Downloads: 0
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7. Volatile and sensory profiling of Shiraz wine in response to alcohol management: comparison of harvest timing versus technological approachesRocco Longo, John W. Blackman, Guillaume Antalick, Peter J. Torley, Suzy Y. Rogers, Leigh Schmidtke, 2018, original scientific article Keywords: Common Component Specific Weights Analysis, polypropylene membrane, sensory descriptive analysis, sequential harvest, volatiles, wine alcohol-reduction
Published in RUNG: 17.09.2018; Views: 4381; Downloads: 0
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8. A comparative study of partial dealcoholisation versus early harvest: Effects on wine volatile and sensory profilesRocco Longo, John.W Blackman, Guillaume Antalick, Peter J. Torley, Suzy.Y Rogers, Leigh Schmidtke, 2018, original scientific article Keywords: Common component and specific weights analysis, Dealcoholisation, Early harvest, Evaporative perstraction, Lower alcohol wine, Reverse osmosis, Sensory descriptive analysis, Wine
Published in RUNG: 17.09.2018; Views: 4431; Downloads: 0
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10. Harvesting and blending options for lower alcohol wines: a sensory and chemical investigationRocco Longo, John W. Blackman, Guillaume Antalick, Peter J. Torley, Suzy Y. Rogiers, Leigh Schmidtke, 2017, original scientific article Keywords: PLS regression, early harvest, herbaceous, reduced-alcohol, sensory descriptive analysis, volatiles
Published in RUNG: 30.08.2017; Views: 4997; Downloads: 0
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