Normativni a deskriptivni pristupy k rozhodovani. Normativni ramec rozhodovani o vyrobkovem protfoliu.

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Hodnoceni vykonnosti podniku pomoci komplexnich efektu

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Zelena chemie a zdravy clovek na prelomu druheho a tretiho tisicileti.

Supplement: 1 videocasette (the film Green chemistry).Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Chemie a technologie epitaxnich struktur polovodivych materialu typu A III B V

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Chovani souboru castic v neizotermnim tavicim prostoru s proudenim

This work deals with utilization of composite models (postmodels) for the calculation of particle concentration fields in a melting space and searches for mutual relations between inhomogeneity arrays and continuum (melt) if gaseous inhomogeneities (bubbles) or solid particles (segregated spinel crystals) are present in the melt. The composite computational model of bubble arrays behaviour in a melt was done by using knowledge of the individual bubble behaviour and in advance calculated temperature and velocity fields as well as fields of distribution of oxidation-reduction species inside a 3D melting space. The influence of the input data (initial and boundary conditions) on the distribution of bubbles in the melting space and on the course of process was accomplished by a parametric study. The parametric study showed basic trends and significance of the individual input data for the melting process. The composite computational model of solid particles (segregated spinel crystals) behaviour in the melt was implemented by using knowledge of the individual particle behaviour and in advance calculated temperature and velocity fields inside the HLW melter (a facility for high level waste vitrification). The model includes crystals coming from the batch blanket (cold cap), crystals nucleated inside the region under liquidus temperature, as well as kinetic behaviour of spinel crystals in nonisothermal melting space with flowing glass. The accomplished parametric study dealt with the impact of initial conditions on distribution of spinel crystals in the melting space and with the influence of settling crystals on the sludge layer thickness at the HLW melter bottom, canal input, canal output of the HLW melterAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Selektivni sorpce tezkych kovu.

The first part of the study is concerned with the sorption of free cation Ni. The following exchangers were used in the experimental study: dimethylsmine anion exchanger, oligo(ethyleneamine) anion exchanger, poly(ethyleneaminated) chitosan, bis-picolylamine anion exchanger, carbolic cation exchanger. Experimental results show that the applications of oligo(ethyleneamine) resins and poly(ethyleneaminated) chitosan in the free base form are optimal for the selective sorption of nickel. Standard weak base anion exchangers are not aplicable to the sorption of heavy metals, because they have low sorption capacities and restricted condition for the effective sorpiton. The carboxylic cation exchanger exhibits much greater sorption capacity, but this resin is not able to remove nickel from a mixture of cations selectively. Cation Mg (II) is not taken up by all anion exchangers. The presence of Mg (II) increased their sorption capacities and decreased the breakthrough levels of nickel to the filtrate. The effect of pH value was following: the increased pH value increased sorption capacities and decreased breakthrough levels. The change of the solution flow-rate was very important, because higher solution flow-rate caused the decrease of the sorption capacity and the increase of the breakthrough level. The second part of study is concerned with the sorption of heavy metals from complexes with EDTA. Copper, nickel and lead were chosen for these experiments, which were carried out on the oligo(ethyleneamine) resin with TEPA functional groups and on poly(ethyleneaminated) chitosan. Both these exchangers are capable to remove heavy metals selectively from complexes with EDTA.Poly(ethyleneaminated chitosan needs lower excess of cation Mg (II) for the effective sorption. Oligo(ethyleneamine) exchanger requires higher ratio in the feed solution, compared to chitosan. Chitosan exhibits the lower sensitivity to solution flow-rate. The cation Mg (II) is not taken up by both exchangers. Its presence increased their sorption capacities and decreased breakthrough levels. Oligo(ethyleneamine) exchanger is not able to remove chelated heavy metals from solution without the presence of Mg in the feed solution. The increased solution flow-rate decreased sorption capacities. The decrease of sorption capacity by poly(ethyleneaminated chitosan was lower than by oligo(ethyleneamine) resin. The sorption of lead was measured on poly(ethyleneaminated) chitosan. These sorptions were not effective. The sorption of Cu and Ni from the bimetallic solution was measured on poly(ethyleneaminated) chitosan. The results show higher preference of exchanger to cu than to Ni.Available from STL, Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Studium inhibice koroze zeleza v kyselem prostredi

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Hydrorafinacni katalyzatory dopovane iridiem

The present work deals with modification of ?-Al2O3 supported Mo and NiMo catalysts by various amounts of iridium. Amount of iridium varied in an interval 0,1 - 1,1%. Besides mixed IrMo and IrNiMo catalysts, the monometallic Ir (1%) and Mo catalysts were studied. All catalysts were prepared by impregnation. The effects of used starting iridium compound (Ir(AcAc)3, Ir(CO)12, H2IrCl6 and (NH4)IrCl6), iridium dispersion and presence of sulfur were evaluated. The activities of prepared catalysts containing Ir were compared with activities of Mo and NiMo catalysts. The prepared catalysts were tested in model reactions of parallel hydrodesulfurization of thiophene and hydrodenitrogenation of pyridine. The reactions were carried out in gas phase at temperature 320 C and pressure 2 Mpa. The catalysts were tested either in sulfided or reduced form in a flow reactor with fixed bed. The products were analyzed by on-line gas chromatography. Activity of catalysts was evaluated at least at three various W/F ratios. The obtained data were described by first-order kinetic equations. One equation described HDS of thiophene and two equations were used for HDN of pyridine. The rate constants were calculated by optimization of obtained primary data. These rate constants were used as indexes of activity and were also used for definition of HDN selectivity (SN) and HDN/HDS selectivity. The prepared catalysts were characterized by using of several techniques: mainly temperature- programmed raduction (TPR), BET surface area, hydrogen sorption (Ir dispersion) and chemical analyses. Selected samples were characterized by transmission electron microscopy. It was found, that the Ir/alumina catalyst prepared from Ir4(CO)122 exhibited the highest activity from all monometallic catalysts. The Ir/alumina catalysts were much more active than conventional Mo and NiMo catalysts. Dispersion of Ir influenced more the C-N bond hydrogenolysis (second step in HDN) than hydrogenation of pyridine (initial step in HDN). The HDN activity of Ir catalysts decreased by sulfidation of reduced catalysts or by thiophene addition in the feed. The effect of Ir content, preparation method and possible presence of promotional effect between Ir and Mo were monitored when studying the mixed IrMo cytalysts. It was observed that Ir addition increased activity of Mo catalysts in both HDS and HDN. However, the synergistic effect was proved only in HDN while not in HDS. This effect was observed in the range of iridium content 0,34 - 0,53%. The results of hydrogen sorption on reduced catalysts and TPR of sulfided catalysts confirmed an interaction between Ir and Mo. The higher activity of modified catalysts is obviously connected with their increased reducibility. Results of hydrogen sorption study and TEM analysis of bimetallic catalysts suggested importance of high Ir dispersion, which significantly influenced the hydrogenolysis of intermediate in final C5 hydrocarbons and ammonia and therefore the overall HDN activityAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Katalyticka hydrogenace 2-ethyl-9,10-anthrachinonu

The dissertational work concerns the catalytic hydrogenation of 2-ethyl-9,10-anthraquinone in liquid phase in a batched isothermal reactor in which the hydrogenatical catalyst in suspension is ideally mixed at atmospheric pressure aiming the effects of solvent, catalyst and conditions of reaction. The mixed solvent was made from polar and non-polar solvents. The non-polar part of the mixed solvent was always Shellsol AB (a mixture of alkyl aromatic hydrocarbons C9 - C11) and the polar part was N, N, N', N'-tetra-n-butylurea, 2-ethyl-hexan-1-ol and 2,6-dimethylheptan-4-ol. The resultant reaction schema of the catalytic hydrogenation of 2-ethyl-9,10-anthraquinone differs from the existing published opinions in the way that the consequential hydrogenation of 2-ethyl-5,6,7,8-tetrahydro-9,10-anthrahydroquinone which creates product of 2-ethyl-1,2,3,4,5,6,7,8-oktahydro-9,10-anthrahydroquinone does not assert in a large scale and 2-ethyl-5,6,7,8-tetrahydro-9-anthrone or 2-ethyl-5,6,7,8-tetrahydro-10-anthrone are created by hydrogenation of the aromatic ring of 2-ethyl-9-anthrone or 2-ethyl-10-anthrone. The values of reaction rate constants and adsorption coefficient were calculated from experimental data by the closest-fitting mathematical model. Some parts of the reaction system were extended by using reverse reactions. The influence of the solvent system on hydrogenation of 2-ethyl-9,10-anthrahydroquinone was evaluated on the basis of the structure of the reaction mixture, reaction rate constants, and selectivity of formation of reaction products depending on the solvent system, weight ratio of solvent and concentration of flowing water. The range of hydrogenation of the aromatic ring of 2-ethyl-9,10-anthrahydroquinone is increasing by decreasing of the weight ratio of solvents, creation of anthrons is accelerated by increasing of flowing water concentration. 2,6-dimethylheptan-4-ol/Shellsol AB is the most suitable solvent system in the production of hydrogen peroxide by anthraquinone processAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi