Support characteristics

Tomography was applied during Transmission Electron Microscopy (TEM) analysis of various reduced Au/zeolite samples. The size and location of the gold nanoparticles as a function of the support characteristics and preparation method are discussed. 

Chromium zeolites are recognised to possess, at least at the laboratory scale, notable catalytic properties like in ethylene polymerization, oxidation of hydrocarbons, cracking of cumene, disproportionation of n-heptane, and thermolysis of H20 [ 1 ]. Several factors may have an effect on the catalytic activity of the chromium catalysts, such as the oxidation state, the structure (amorphous or crystalline, mono/di-chromate or polychromates, oxides, etc.) and the interaction of the chromium species with the support which depends essentially on the catalysts preparation method. They are ruled principally by several parameters such as the metal loading, the support characteristics, and the nature of the post-treatment (calcination, reduction, etc.). The nature of metal precursor is a parameter which can affect the predominance of chromium species in zeolite. In the case of solid-state exchange, the exchange process initially takes place at the solid- solid interface between the precursor salt and zeolite grains, and the success of the exchange depends on the type of interactions developed [2]. The aim of this work is to study the effect of the chromium precursor on the physicochemical properties of chromium loaded ZSM-5 catalysts and their catalytic performance in ethylene ammoxidation to acetonitrile. 

Several supported Pt catalysts were prepared. The supports used are Mg hydrotalcite (HT), SiC>2, amorphous Si02-Al203 (ASA) and LTL zeolite. The support characteristics are shown in Table 1. 

In most cases, it is probably immaterial how these recommendations are interpreted. For media, overcooking is bad because of deleterious effects on growth-support characteristics, and undercooking is generally self-disclosing through evident contamination. 

Catalyst Sample Carbon Support Characteristics Mean Particle Size (HRTEM, nm) ... 

Calculated by empirical correlations that depend on both the species diffusivity and the membrane support characteristics (thickness, tortuosity, and porosity). 

The upper temperamre limits of the supported membranes depend on the material, the chemical atmosphere and the support characteristics such as porosity and pore diameter [54]. 

Cserhati, T. Forgacs, E. Effect of TLC support characteristics and coating on the lipophilicity determination of phenols and aniline derivatives. J. Chromatogr. Sci. 2002, 40, 564-568. 

R-value and Cahfornia Bearing Ratio (CBR) tests are performed to determine subgrade modulus and evaluate the pavement support characteristics of the in situ or fill sods. 

These reduced coefficients identical for each pad, depend on frequency v, pad mass m, pad inertia 1 and 1 and support characteristics... 

On the same research topic, Singh et al. (2010) studied the separation of U(VI) from a phosphoric acid medium by a SLM. The influence of various parameters, such as feed acidity, nature of the stripping solution, carrier concentration, membrane pore size and thickness was studied. The results showed that membrane support characteristics affect the transport of the target ionic species (such as U(VI)) and confirmed that U(VI) separation from phosphoric acid medium by SLM is feasible. System stability was studied by performing ten continuous experimental cycles with 6 hours duration each. The results evidenced a good operational stability, with a quite linear... 

Spite of the simplicity of the copolymerization process, more tunable properties of the functionalized material can be achieved using grafting techniques, as they allow the independent tuning of the support characteristics and of the grafting points. Moreover, the control over the density of the grafted brushes can also be achieved by tuning the initial density of the initiator on the grafting surface. 

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