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This work describes an effective method for the preparation of open-cell ceramic foams for their further use as catalyst supports. The polyurethane sponge replica technique was applied using a ceramic suspension based on a mixture of α-alumina, magnesia and titania and polyvinyl alcohol solution as a liquid component. The polyurethane sponge was etched with NaOH and covered with colloidal silica to obtain better adhesion of the slurry to the walls of the polymeric material onto it. The surface area of the ceramic carrier was increased by adding a layer of γ-alumina. Deposition of an active catalytic phase (Pt) was done by impregnation. Properties of the carriers and the final catalyst were investigated by a number of physico-chemical methods such as TEM, SEM, XRD and computer tomography. Hydrogenation of ethyl benzoylformate was performed to elucidate the catalytic properties of foam catalysts illustrating their applicability.

Five different support materials were modified with 5 wt.% Cu, using an evaporation impregnation method. The synthesized CuCl 2 /γ-Al 2 O 3 , CuCl 2 /TiO 2 (Hombikat), CuCl 2 /TiO 2 (Alfa Aesar), CuCl 2 /SiO 2 and CuCl 2 /H-Beta-25 materials were characterized by nitrogen physisorption, X-ray powder diffraction, scanning electron microscopy, energy dispersive Xray microanalysis, transmission electron microscopy, Fourier transform infrared spectroscopy and CO 2 -temperature programmed desorption. The physical-chemical characterization was correlated with catalytic activity, stability and selectivity in the ethylene oxychlorination. It was found that γ-Al 2 O 3 and TiO 2 support materials demonstrate very good activity and 1,2dichloroethane selectivity compare to other catalysts. Zeolite H-Beta-25 and SiO 2 support materials proved to be unusable for this reaction.

Aqueous-phase reforming of propanol-1, propane-1,2-diol and glycerol was performed at 498 K and 29.7 bar in a continuous reactor with platinum supported on a polymer-derived carbon, as a catalyst. The number of hydroxyl groups of the reactant influenced the product distribution. An unexpectedly long stabilization period − more than 150 h of time-on-stream − was found to be an important feature of the catalyst.

Hydrolysis of the hemicellulose arabinogalactan was studied in this work over several functionalized carbon materials, which were specifically treated to increase their acidities. Hydrolytic hydrog ...

The hydrolytic hydrogenation of hemicellulose arabinogalactan was investigated in the presence of protonic and Ru (1-5 wt.%)-modified USY zeolites (Si/Al ratio = 15 and 30). The use of the purely acidic materials was effective in depolymerizing the macromolecule into free sugars. While the latter partly dehydrated into 5-hydroxymethylfurfural and furfural, the generation of high molecular-weight compounds (aggregates of sugars and humins) was not favored, in contrast to previous evidences over beta zeolites. Application of the bifunctional Ru/USY catalyst, comprising well-dispersed metallic nanopartides on the aluminosilicate support, resulted in the formation of galactitol and arabitol, in the suppression of dehydration side products, and further inhibition of polymerization reactions, which only yielded low molecular-weight oligomers. Detailed analysis of the reaction pathways as well as kinetic modeling of hydrolytic hydrogenation was performed with an advanced reaction mechanism.

Carbon-supported mono- and bimetallic catalysts prepared via incipient wetness impregnation were systematically studied in aqueous-phase reforming (APR) of xylitol aiming at hydrogen production from biomass. The catalytic performance of several VIII group metals and their combinations, such as Pt, Ni, Pt-Ni, Re, Pt-Re, Ru, Pt-Ru, and Pt-Co, was compared for xylitol APR in a fixed-bed reactor at 225 °C and 29.7 bar (N2). Ni/C, Ru/C, and Re/C catalysts displayed significantly lower activity compared to others. Activity and selectivity to H2 of bimetallic Pt-Ni/C, Pt-Co/C, and Pt-Ru/C catalysts were close to that of Pt/C. Pt-Re/C catalyst showed an outstanding performance which was accompanied by a shift of the reaction pathways to the alkane formation and thereby lower hydrogen selectivity. Addition of the second metal to Pt was not found to be beneficial for hydrogen production, thus leaving Pt/C as the optimum carbon-supported catalyst.

The aqueous phase reforming (APR) of xylitol was studied in a continuous fixed bed reactor over three catalysts: Pt/Al2O3, Pt/TiO2 and Pt-Re/TiO2. The data obtained in the case of the monometallic Pt catalysts was compared to the bimetallic Pt-Re sample. The effect of Re addition on the catalyst stability, activity, product formation and selectivity toward hydrogen and alkanes was studied. The bimetallic catalyst demonstrated a higher selectivity to alkanes compared to the monometallic samples. The monometallic catalyst was more selective toward hydrogen formation. A plausible reaction scheme explaining differences in selectivity toward hydrogen and alkanes was proposed and discussed.

The behavior of abundant polyol stemming from hemicelluloses, xylitol, was investigated in the aqueous phase reforming (APR) over supported Pt/Al2O3. The data obtained in the case of xylitol was co ...

Kinetics of the hydrogenation of β-sitosterol to β-sitostanol is of industrial interest, since the desired product is used for suppressing cholesterol absorption in human body. The main drawback when using microporous Pd/C catalyst in this reaction is catalyst deactivation. In the current work the performance of microporous and mesoporous Pd catalysts in the hydrogenation of β-sitosterol was compared. The catalytic hydrogenations were performed in a shaking batch reactor in 1-propanol as a solvent. With larger amounts of catalyst less catalyst deactivation occurred due to the fact that the catalyst support acted also as an adsorbent. The mesoporous 4 wt.% Pd/C (Sibunit) catalyst showed higher sitosterol conversions and less catalyst deactivation compared to a microporous 5 wt.% Pd/C catalyst. The kinetics of the hydrogenation of β-sitosterol to β-sitostanol was studied over 4 wt.% Pd/C (Sibunit) catalyst at different temperatures between 60 °C and 80 °C and by reusing the catalyst. The origin for catalyst deactivation was poisoning by phosphorus and sulphur, as well as coking. In situ catalyst potential measurements showed that there is a correlation between catalyst deactivation and decreasing catalyst potential with increasing sitosterol conversion. A mechanistic kinetic model including a deactivation factor was successfully applied to this reaction and the kinetic parameters were determined.

Various supported gold catalysts were utilized in aerobic lactose oxidation. Comparison between these catalysts revealed, that gold catalysts are sensitive to the type of support. Kinetic regularities, e.g. dependence on pH, temperature and oxygen feed rate were established. Gold catalysts were selective for the production of the first reaction product, sodium salt of lactobionic acid. The electrochemical catalyst potential response was measured “ in situ ” and then utilized in the reaction process characterization.

Gold and palladium catalysts were successfully applied in aerobic d -lactose oxidation. Comparison between these catalysts revealed, that gold catalysts are more active and selective for the production of the first reaction product, lactobionic acid, while Pd can be of importance when the product of second consecutive reaction, 2-keto-lactobionic acid is aimed at. The electrochemical catalyst potential response was measured in situ applied for characterization of processes on the catalyst surfaces. Several reaction parameters were varied to study possibilities to predict catalyst deactivation from the measured catalyst potential.

Kinetics and reaction mechanism of catalytic hydrogenation and oxidation of d -lactose were studied in three-phase laboratory reactors. Catalyst screening results and influence of temperature, pressure, catalyst loading and pH are reported as d -lactose was either catalytically hydrogenated to lactitol or oxidized to lactobionic acid. The product yield was significantly influenced by reaction conditions and catalyst choice. Additionally, during oxidation and hydrogenation processes, catalyst deactivation was severe under non-optimized conditions. Temperature dependency of lactose mutarotation was determined by NMR analysis.

Kinetic behaviour of catalyst electrochemical potential was studied during three-phase heterogeneous reaction of d -lactose oxidation. The influence of different factors on in situ measured catalyst electrochemical potential is considered. A kinetic model capable to explain transient behaviour of catalyst electrochemical potential at different conditions such as conversion, oxygen partial pressure, temperature and pH is proposed.

Possibility of the cyclic voltammetry (CV) in characterization of supported VIII group metal catalysts was studied. The emphasis was laid on Pd catalysts. A standard procedure for CV measurements was proposed and validated. Reasons causing cumbersome behavior of copper underpotential deposition (UPD) were revealed. The relative surface areas of metal catalysts on conductive and non-conductive supports were measured.

The aqueous phase reforming (APR) of xylitol was studied over five Pt/C catalysts. The correlation between physico-chemical properties of the catalysts and catalytic performance was established. The Pt/C catalysts have different textural properties as well as different mean Pt cluster sizes and surface acidity. The average Pt cluster size was investigated by means of CO chemisorption as well as by TEM. The reaction was found to be structure sensitive and TOF linearly increases with increasing average Pt cluster size in the studied domain. The catalysts which possess higher surface acidity favoured higher rates of hydrocarbon production. On the contrary the Pt/C materials with lower acidities generated hydrogen with high selectivity and TOF.

This paper presents the algorithm of terrain objects edge detection in GPS images. This objective is relevant for two reasons. Firstly, in case of distortions occurring in the process of data transmission through communication channel, and secondly, in many cases preliminary data processing requires edge detection. To solve the first issue we utilize quasi-2D filtration, and to solve the second we use an algorithm based on Canny edge detection algorithm.