Vliv prirodnich soucasti chladicich vod na korozi a tvorbu usad

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Sledovani jakosti potravin se zamerenim na falsovani citrusovych stav

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Matematicky model reaktoru pro oxidaci amoniaku

Four types of mathematical models of reactors for the ammonia oxidation were developed, namely: simplified diffusion model, two phase model of ideally mixed reactors cascade, two phase plug flow model and two phase plug flow model considering axial dispersion. These models take into consideration mass and heat transfer in the catalytic bed including heat exchange in the reactor via radiation as well as the influence of the temperature on the reaction mixture composition and physicochemical properties. The balance equations were solved by the shutting method, global orthogonal collocation method and method of orthogonal collocation on the finite elements. It was found that shutting method is not suitable for the solving of these model equations. Developed mathematical models were compared on the basis of the criteria taking into the account their ability to describe the basic experimentally determined trends, computing time, accuracy of the results and their stability. On the basis of these criteria the two phase plug flow model with axial dispersion was evaluated as the most suitabel and this model was used in the following studies. The influence of the boundary conditions and choice of the "reference stay" used for computation of transport and physicochemical properties was studied. It was found that the choice of "reference stay" effects the obtained results. The parametric study of the reactor in the middle pressure unit for nitric acid production was performedutilising GPM method. This method had to be modified for the purposes of this study. It was necessary to reduce the choice of the fixed variables in the solution corrector, to introduce the control of the step lenght along the parametric curve in the dependence on the number of iterations in the solution corrector and on the magnitude of the changes in the estimated solution. The influence of the load, pressure, catalyst specific surface, composition and preheating of input gases on the ractor behaviour was studied using this method. The calculated values are in good agreement with the experimentally determined dependencies. E.g. the calculated ignition temperature 200 C is in accordance with the value observed experimentally. The developed model in connection with the commercial software ASPEN PLUS was used for optimisation study of the nitrogen oxide production unit in regard to the maximum concentration of NO in unit gases. On the basis of these results an pilot plane scale production unit was designedAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Studium chovani organokremicitych konsolidantu kamene

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Priprava a studium vlastnosti hydrofilnich polymernich nosicu biologicky aktivnich molekul

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Dynamicke chovani nelinearnich chemickych a biochemickych systemu

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Chemicka knihovna zalozena na palladiem katalyzovane tvorbe C-C vazby

Combinatorial synthesis based on the repeated Stille coupling of 3-tributylstannyl allyl alcohols was the aim of this study. These 3-tributylstannyl allyl alcohols are building blocks of target molecules. Their synthesis are described in the first part of this work. These stannanes were synthesized by several methods. Most of the stannanes (14) were prepared by hydroalumination of substituted propargylalcohols followed by transmetalation to tin. This already known method we optimized and improved by using tributyltin methoxide as a transmetalation agent. This method enables easy preparation of 3-tributylstannyl allyl alcohols in amount up to 50 mmol in 30-74% yields. Another group of stannanes were prepared by nucleophilic substitution of chlorine in (Z)-6-chloro-3-tributylstannyl-2-hexin-1-ol. Starting (Z)-6-chloro-3-tributylstannyl-2-hexin-1-ol was prepared employing reactivity of stannyl cuprates. Stannanes having amide group on the side chain were prepared by palladium catalyzed hydrostannation. This reaction provides the mixture of 2- and 3-tributylstannyl allyl alcohols, which were separated by chromatography. Stille reaction of these stannanes on the solid phase is described in the second part of this work. Firstly the solid phase synthesis of cinnamyl alcohols by reaction of 3-tributylstannyl allyl alcohols with 4-iodobenzoate was optimized. The process of activation of this cinnamyl alcohol and reaction of formed product with the next 3-tributylstannyl allyl alcohol was optimized afterwards. This reaction conditions were used for the synthesis of the desired library. Solid phase synthesis with other iodobenzoic acids and 2-tributylstannyl allyl alcohols were shown as well. The third part of the thesis deals with direct Pd-catalyzed coupling of arylhalides with organoaluminium compounds obtained by reaction of LiAlH4 with substituted propargyl alcohols. 3,3-Disubstituted allyl alcohols were prepared by this method directly from 3-substituted propargyl alcohol and corresponding aryliodide. Synthetic utility of this reaction was demonstrated on the 14 examplesAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Studium inhibice koroze

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Aniontova polymerizace a kopolymerizace laktamu

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Vysoce pevne hydratovane anorganicke materialy na bazi cementu

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