Catalysis solid

Significant characteristics of homogeneous catalysis are that they are highly specific and proceed under relatively mild conditions— again in contrast to solid catalysis, which is less discriminating as to reaction and may require extremes of temperature and pressure. A problem with homogeneous operation is the difficulty of separating product and catalyst. 

Data of chemical composition 106 Pressure changes 145 Variables related to composition 164 Half iife and initial rate data 177 Temperature variation. Activation energy Homogeneous catalysis 202 Enzyme and solid catalysis 210 Flow reactor data 222 CSTR data 231 Complex reactions 238... 

The mechanism of solid catalysis involves processes of diffusion, formation of loose combinations with the solid and reactions of those combinations. Reactions with enzymes also involve intermediate, temporary combinations with the enzymes. The rate equations that may proposed in particular cases depends on what are believed to be controlling mechanisms. Many such eqautions are considered in Chapter 6. Here only one of the simpler forms will be examined for evaluation of the parameters, namely,... 

It is important to emphasize that the atomic oxygen anion-radical plays a role in catalytic oxidation occnrring on varions oxide surfaces. For instance, O reacts with methane at room temperatnre over varions metal oxides (Lee and Gralowsky 1992). On solid catalysis, Q- is more reactive toward alkanes and alkenes than other ionic oxygen species. Iwamoto and Lnnsford (1980) assumed that O is the active oxygen species oxidizing benzene to phenol on with 70% selectivity at... 

The most important point about the alkyl halide reactivities in triphase catalysis is that the reactions which have the highest intrinsic rates are the most likely to be limited by intraparticle diffusion. The cyanide ion reactions which showed the greatest particle size and cross-linking dependence with 1-bromooctane had half-lives of 0.5 to 2 h and with benzyl bromide had half-lives of 0.13 to 0.75 h. The reactions of 1-bromooctane and of benzyl chloride which were insensitive to particle size and cross-linking had half-lives of 14 h and 3 h respectively. Practical triphase liquid/ liquid/solid catalysis with polystyrene-bound onium ions has intraparticle diffusional limitations. 

Triphase liquid/liquid/solid catalysis has been carried out with a continuous flow reactor 120). A mixture of 1-bromooctane in o-dichlorobenzene and aqueous potas-... 

Modeling of bubbling fluidized beds with reaction (gas-solid catalysis case and Type B Fluidization)... 

Liquid-solid particulate fluidization (liquid-solid catalysis, adsorption, and ion exchange)... 

As a consequence of the line broadening effects of internal magnetic interactions on solid-state NMR spectra (Section ILA), experiments that characterize working solid catalysis require the application of the MAS technique. Because of the salient feature of MAS NMR spectroscopy (rapid sample spinning during the measurement), specific techniques had to be developed to allow characterization of solids in sealed vessels under batch reaction conditions and in fixed-bed reactors under flow conditions. 

Many reaction processes of industrial importance occur in microporous solids (catalysis, electrolysis, shale retorting, etc.). Access to the interior of the solid is by diffusional transport and the transport of mass is usually described by Fick s law. The parameter describing the ease of mass transport is the effective diffusivity, De, where... 

Tliese results revealed that the liquid/liquid interface produced by agitation or stirring could catalyse the extraction rate by increasing the interfacial concentration of extractant and facilitating the interfacial complexation rate, similar to gas/solid or liquid/solid catalysis. 

Probable mechanisms often have been deduced The reactant forms a short-lived intermediate with the catalyst that subsequently decomposes into the product and regenerated catalyst. In fluid phases such intermediates can be detected spectroscopically. This is in contrast to solid catalysis, where the detection of intermediates is much more difficult and is not often accomplished. 

Water Issue and the Role of Solid Catalysis in Promoting New Technologies... 

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