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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.

The present study was focused on kinetic investigation of xylitol aqueous phase reforming with 2.5%Pt/C catalyst in a fixed bed reactor. For kinetic modeling, a complex reaction network was taken into account considering the formation of not only hydrogen and CO2 but also a range of alkanes in various side reactions. Parameter investigation revealed an adequate description of the experimental data. The influence of mass transfer was elucidated by exploring the parameter space of diffusion and mass transfer coefficients as well as Peclet numbers. Aspen HYSYS software was used to design a hydrogen production plant with 500 kg/h capacity operating with xylitol as a feedstock. Heat consumption of the designed process can be fully covered by heat generated by combusting alkanes formed during APR reaction.

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 influence of substrate chirality was studied in the aqueous phase reforming (APR) over Pt/Al2O3 in a continuous fixed-bed reactor at 225 °C. Two epimeric sugar alcohols, namely sorbitol and galactitol, were used for performance comparison. For the very first time galactitol was used in the APR process. The reliability of the liquid-phase product analysis was considerably improved due to application of a spiking technique for qualitative analysis and subsequent peak fitting for quantification. A detailed analysis of the gas and liquid phases showed almost the same behavior of both polyols, apart from the formation of several intermediate oxygenates. This implies that industrially relevant feedstocks with different chiralities can be efficiently processed in APR, since the chirality of the initial substance does not affect the reaction rate and selectivity to the final products. However, the observed difference in the liquid phase composition should be considered, because the catalyst should be active i...

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 hydrolytic hydrogenation of hemicellulose arabinogalactan using different beta zeolites as catalysts was studied in this work. The use of bifunctional Ru/β zeolite catalysts leads to formation of valuable polyols (galactitol, arabitol) from hemicellulose. The presence of acid sites enhances hydrolysis of the hemicelluloses into sugars in addition to homogeneous hydrolysis while the Ru catalyzes further hydrogenation into polyols. Using bifunctional catalysts the stability of these polyols can be also enhanced because the side reactions to HMF and furfural were minimized, however formation of high molecular weight compounds (aggregates of sugars and humins) was still quite substantial.

Aqueous-phase reforming of polyols was investigated in the current work by mathematical modeling using sorbitol, which represents a C6-polyol originating from biomass processing. The reaction was studied in the presence of Pt/Al2O3 catalyst at 498 K and 29.3 bar in a continuous fixed-bed reactor under kinetic control. The feasible scheme describing main pathways of sorbitol transformation was proposed considering experimental and literature data. The kinetic model was compared with experimental data through numerical data fitting showing good correspondence.

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 ...

The influence of hydrogen on the catalytic deoxygenation of fatty acids was investigated in the semibatch reactor over a mesoporous 5 wt % Pd/C (Sibunit) catalyst. Transformations of a model fatty ...

A dual-fluidized bed reactor was applied in the pyrolysis of pine wood and catalytic upgrading of the pyrolysis vapors over H-Beta zeolite. The temperatures of the pyrolysis and catalytic upgrading reactors were 400 and 440 °C, respectively. The effect of space velocity on the yield and composition of pyrolysis products was investigated. It was found that the catalytic upgrading affects all pyrolysis products, except the char yield which can be considered constant at all space velocities. By lowering the space velocity the gas, water and coke yields increased at the cost of the organic phase of the bio-oil. The coke yield was fairly high, 11 wt% of the biomass, at the lowest space velocity. The spent catalysts could be regenerated by burning away the formed coke and thereby regaining the surface area and most of the acid sites.

Several mono- and bimetallic Pd, Pt, Rh and Ru supported on alumina and active carbon catalysts were characterized by CO chemisorption, nitrogen adsorption, XPS and XRD and acidity titrations were performed for active carbon supported catalysts. These catalysts were tested in oxidation of two sugars, namely lactose and rhamnose, at 60 °C and at 70 °C under slightly alkaline conditions (pH 8) with molecular oxygen. The results revealed that there is an optimum metal particle size in a range of 3-10 nm giving the highest initial TOFs for both oxidations. Furthermore, the catalytic activities and conversions were related to other catalyst properties, such as the type and amount of promoters and the presence of different phases. In situ catalyst potential measurements revealed that there is an inverse correlation between the increase of catalyst potential as a function of sugar conversion and the catalyst activity after prolonged reaction times. This method is a valuable tool for in situ characterization of catalysts correlating well with their activities.

The kinetics and reaction network of the onepot synthesis of R1phenylethyl acetate was investigated at 70°C in toluene over a combination of three different catalysts: PdZn/Al2O3 as a catalyst for ...

Aqueous Phase Reforming (APR) has during the recent years emerged as a potent, alternative means of processing raw materials of biological origin to component suitable as chemicals and fuel compone ...

Lactose oxidation was investigated at 70 °C and at pH 8 using oxygen as an oxidant over a comprehensive set of commercially available mono- and multi-metallic as well as promoted Pd catalysts with active carbon, alumina and calcium carbonate as catalyst supports. An optimum cluster size of 6–10 nm resulted in the highest initial turnover frequencies. High conversion levels above 90% were achieved on Pd/C catalyst, as well as over Pd/Al2O3 and (Pd–Pb)/CaCO3, whereas (Pd–V)/C catalyst gave only 30% conversion after 200 min. The latter catalyst was relatively inactive due to its high support acidity and profound deactivation during oxidation. Besides the main oxidation product, lactobionic acid, also, lactulose was generated as a result of lactose isomerisation under alkaline conditions. The electrochemical potentials of the catalysts were measured during lactose oxidation. The main result of these measurements was that, when the electrochemical potential of the catalyst increased very quickly, its oxidation activity was low due to metal over-oxidation. The selectivities to the desired product, lactobionic acid, were relatively high, above 80% for most of the catalysts, except for (Pd–V)/C. Furthermore, the selectivity to the lactobionic acid decreased with increasing metal dispersion, thus, indicating that the optimum metal particle sizes for producing high amounts of lactobionic acid is above 3 nm.

Aqueous phase reforming of sorbitol over Pt supported on an alumina catalyst is investigated, in order to identify the intermediates involved in the transformation of the initial feed. Parameters such as the sorbitol feed rate and temperature are studied. To identify the intermediates, an approach based on analysis of the gas and liquid phases as well as the total carbon content was developed. According to analysis by gas chromatography combined with mass spectrometry of volatile substances collected with solid-phase microextraction, over 260 compounds are involved in the transformation of sorbitol. Of these, 50 of the major products are identified with high reliability. It is shown that a great variety of compounds, bearing different functionalities, form part of the reaction network. The formation of the majority of identified compounds is explained and a reaction network for the formation of sorbitol and intermediate molecules transformation is proposed.

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.

Lactose oxidation kinetics was studied on an supported gold catalyst with simultaneous control of catalyst potential. The experimental data were described well by the suggested mechanism and kinetic model of this reaction.

Liquid-phase lactose oxidation was investigated over supported Pd/C and Pd-carbon nanofibre catalysts, which were characterized by several methods. A complex relationship between catalyst activity and catalyst acidity was established, i.e. optimum catalyst acidity resulted in the highest activity in lactose oxidation. In-situ catalyst potential measurements during lactose oxidation gave information about the extent of accumulation of oxygen on the metal surface. These results could be correlated with catalyst deactivation, which was extensive over the most acidic catalysts at low reaction temperatures. Selectivity for the desired product, lactobionic acid, was a maximum of approximately 83% at 93% conversion. The main side-product was lactulose formed via isomerisation of lactose. Lower selectivity toward lactobionic acid was obtained when the rate of oxidation of lactose was low.

Lactose oxidation to lactobionic acid was investigated over palladium forms of Beta and MCM-22 zeolites. Different support acidity and the method of palladium introduction were applied. It was observed that the catalyst preparation methods, as well as acidity, influence the activity and selectivity. Pd-H-MCM-22 zeolites were more active, than palladium on conventional supports, for instance silica and alumina, or beta zeolite. In situ catalyst electrochemical potential measurements were applied as a source of supplementary information to monitor the coverage of adsorbed species, in particular oxygen, during the reaction.

High catalytic activity was achieved in the deoxygenation of stearic acid in dodecane in a temperature range of 270–300 °C under 17 bar helium over palladium on nanocomposite carbon Sibunit. Besides n-heptadecane, which was obtained previously in this reaction with palladium on activated carbon, n-pentadecane was also formed in significant amounts.

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.

The synthesis and catalytic properties of Pd, Pt, Ru nanoparticles in nanostructures of polymers are described. The controlled growth of metal nanoparticles in a polymer matrix was achieved. The catalytic systems have been studied in selective oxidation of monosaccharide. These processes are of particular interest because the products are the intermediates in the synthesis of biology active substances.