A series of Pt-skin type catalysts has been synthesized in order to substantially enhance their specific and mass activity in MOR and ORR Ž two reactions known to have high activation polarization. Due to strain and ligandeffects the Pt-skin catalysts shift the ORR potential to higher values by 50 mV. Adding Ru to the most active PtCu/C ORR catalyst creates a wider potential window in which MOR has a five-fold current density with respect to commercial PtRu (1:1)/C catalyst
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 5034266Mechanism of alcoholysis (e.g. methanolysis) using different oils, alcohols and homogeneous base catalysts was utilized to devise chemical kinetics and thermodynamics based on fatty acid composition, differentiating among triglycerides, diglycerides, monoglycerides and fatty acid alkyl esters (e.g. fatty acid alkyl esters, FAME) with bonded gadoleic, linoleic, linolenic, oleic, palmitic and stearic acid-originating substituents. Their concentrations were measured using an optimized high-performance liquid chromatography (HPLC) method. Hydrodynamics and diffusion limitations in emulsion were considered in overall model by determining diffusivities, distribution coefficients, molar volumes, boiling points and viscosities of individual components. Pre-exponential factors and activation energies were related with structure of reactants, intermediates and products acknowledging number of carbons, double bonds and alkyl branches by linear and mixed response surface methodology. Developed model may be used with batch and continuous flow reactors, e.g. for novel micro-structured or industrial-scale process intensification, different vegetable or non-edible oils.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 5447450Innovative second-generation biofuel was obtained by a low-temperature ultrasonic liquefaction of waste wood biomass in glycerol, diethylene glycol and p-toluenesulfonic acid, and its hydrotreatment in the presence of various heterogeneous catalysts and hydrogen donor solvents. Depolymerization and solubilization of cellulose, hemicellulose and lignin by using residual glycerin from biodiesel production make solvolysis process highly sustainable thermochemical biomass to liquid (BtL) route. Solvolytic oil containing 25–33 wt% of liquefied spruce and fir sawdust was upgraded by hydrotreatment utilizing heterogeneous catalysis at 300 °C and 8 MPa of hydrogen pressure. Prior to kinetic experiments, mass transfer and heat transfer resistances were reduced, and activity of catalytic hydrocracking and hydrodeoxygenation (HDO) was investigated for four NiMo/Al2O3 bifunctional catalysts in oxide, reduced and sulphide form, Ni/Al2O3–SiO2, MoS2, Pd/Al2O3 and Pd/C. Promoting effects of hydrogen donor solvents were investigated for tetralin, phenol, 2-propanol, pyridine, m-cresol, anthracene, cyclohexanol and xylene. Lumped reaction kinetic model was developed to determine kinetics of hydrogenolysis, decarboxylation, decarbonylation and hydrocracking of products of liquefaction, such as levulinic acid, guaiacol and hydroxymethyl furfural (HMF), according to their functional groups and related gaseous products, quantified by Fourier transform infrared spectroscopy. Upgraded liquid product was also characterized for energetic and fuel applications by following its rheological properties and measurements of gross calorific value.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 5395994Both in the pharmaceutical industry and in pharmacology, crystallization and dissolution processes play an important role in the production and physiological action of active pharmaceutical ingredients. For the first, recrystallization or other phase transformations present an indispensable step in downstream separation and purification processing, while for the second, solubility is of vital importance for drug delivery systems such as tablets. In the present study, the anhydrous form of amlodipine was investigated from its basic structural and conformational characteristics using molecular modeling, to the laboratory-scale formation of its solid phase from solution, and finally, to industrial-size operation by applying models, based on the hydrodynamic characteristics in the crystallizer due to mixing (computational fluid dynamics (CFD)), transport phenomena (specifically heat transfer), and population balance modeling. Simulations revealed that an efficient process intensification and control may be realized through the seeding and widening of the metastable zone (nucleus absence albeit supersaturation), providing a uniform and monodisperse size distribution.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 5502746Raw residual wood biomass, containing cellulose, hemicellulose and lignin, was liquefied at low temperature by ultrasound-assisted solvolysis and acidolysis by glycerol, diethylene glycol and p-toluenesulfonic acid. Liquefied biomass was consequently upgraded by hydrotreatment utilizing heterogeneous catalysis over NiMo/Al2O3 bifunctional catalyst. Effects of temperature (200−350 °C), heating rate (2.5–10.0 K min−1), hydrogen/nitrogen pressure (2−8 MPa), mixing (250−1000 min−1), hydrogen donor solvent (tetralin) and catalyst contents on deoxygenation were established. Reactions of liquefaction products, such as levulinic acid, were quantified based on their functional groups by Fourier transform infrared spectroscopy, whereas catalyst was examined by scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction analysis (XRD). Chemical kinetics of hydrodeoxygenation (HDO), decarbonylation and decarboxylation were determined by originally developed lumped model, based on reaction mechanisms and pathways, while the external mass transfer resistance proved to be negligible under the applied hydrodynamic conditions. The presence of hydrocracking reactions was confirmed by a decrease in product viscosity, and the upgrade for energetic or fuel applications by measurements of calorific value
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 5432346