Hydrotreatment of liquefied lignocellulosic biomass was investigated at 300 °C under the total pressure of 8 MPa in a slurry reactor over unsupported molybdenum (disulphide, dioxide and carbide) and tungsten (disulphide) catalysts. Novel nanostructured urchin-like MoS2 and inorganic-fullerene MoS2 interconnected with carbon materials were synthetized and tested, while the influence of metal variation and the sulphide replacement with carbide or oxide was also investigated by using commercially-available MoS2, Mo2C, MoO2 and WS2. Catalysts were structurally characterised by field-emission scanning (SEM) and high-resolution transmission (HRTEM) electron microscopies, energy-dispersive X-ray (EDX) and Raman spectroscopies, as well as X-ray diffraction (XRD). The hydrodeoxygenation (HDO), decarbonylation, decarboxylation and hydrocracking kinetics of depolymerised cellulose, hemicellulose and lignin were determined according to the transformation of their functional groups in liquid phase, and the corresponding gaseous products by an innovative lumped kinetic model based on Fourier transform infrared spectroscopy. Unsupported MoS2 catalysts showed high hydrogenolysis selectivity, the morphology clearly affecting its rate. A high HDO activity reflected in the mass balance and phase distribution of the upgraded liquid product by reducing tar residue and increasing the yield of oil phase with the gross calorific value of 38 MJ kg−1 and oxygen content below 8.5 wt%.
COBISS.SI-ID: 5537562
Solvolysis of wood, cellulose, hemicellulose and lignin in glycerol was investigated in the presence of homogeneous imidazolium-based ionic liquid (IL) catalysts, where the influence of the IL type, reaction time, temperature and mass transfer limitations on decomposition rate was investigated. The selection of anions (acetate, hydrogen sulphate or chloride/metal halide complex to form a Lewis acid) and cations (butyl-, methyl- or allyl-functionalised imidazolium) importantly influenced conversion, which was as high as 64.4 and 91.5 wt% for the beech wood liquefaction at 150 and 200 °C within 60 min. By following the mass of solid particles and their specific surface area (BET method) as a function of time and temperature, a novel kinetic model for the solvolysis of biomass and its components was developed, where reactive surface area is a key parameter that dictates the rate of solid–liquid reaction; kinetic model also considered different depolymerisation reactivity of main three wood components. Liquefied biomass was consequently hydrodeoxygenated at 225–275 °C in the presence of commercially available sulphide-form NiMo/γ-Al2O3 catalyst. Rates and selectivity of hydrogenolysis, decarbonylation, decarboxylation, hydrogenation and (hydro)cracking were followed and modelled by using previously developed lumped kinetic model, based on the Fourier transformed infrared spectroscopy (FTIR) analysis. The oxygen content of the oil phase of was less than 1.7 wt%.
COBISS.SI-ID: 37882629
Photocatalytic phenol dissociation was studied in a microreactor, with a TiO2 layer immobilized on the reactor inner walls. Experiments were conducted for various residence times, initial concentrations, pH values, and UV light irradiation intensities. The intermediates and products (catechol, hydroquinone, and resorcinol) were quantitatively investigated to determine the predominant reaction pathways for the investigated anatase catalyst. A three-dimensional mathematical model was used to simulate the heterogeneous photocatalysis reaction conditions with Langmuir–Hinshelwood mechanism, considering the adsorption/desorption thermodynamic equilibria, and for kinetic parameter estimation via regression analysis.
COBISS.SI-ID: 5567258
A co-precipitation method was used for the synthesis of a novel copper–ceria catalyst promoted with gallium. Structural characterization was performed by SEM, EDS, BET, XRD, and XPS techniques. Methanol steam reforming was conducted inside a miniaturized LTCC packed bed reactor in the temperature range of 300–400 °C, and hydrogen was successfully produced from a water and methanol mixture. The kinetics of the reforming process were evaluated and the operation of the miniaturized reactor was described with a 3D finite element model, which included all governing mechanisms: fluid dynamics, transport phenomena and reaction kinetics
COBISS.SI-ID: 37864965
The sorption reaction CaO–CO2 was examined in a countercurrent gas–solid trickle flow reactor with regularly stacked packing at T5500–600C, pCO2540–50 kPa, solid-phase fluxes S50.3–0.5 kg m22 s21, and CaO particles of 500–710 lm in size. Sorption kinetics was evaluated by thermogravimetric (TG) technique. The random pore model was used for the description of the carbonization reaction. Hydrodynamic characteristics of gas–solid trickle flow were estimated at room temperature and ambient pressure. Plug flow model of both gas and solid-phase, with the parameters obtained from TG and hydrodynamics experiments, satisfactorily described the sorption process in countercurrent gas–solid trickle flow reactor.
COBISS.SI-ID: 5660186