Catalysts physicochemical properties

Metal contaminants when deposited onto fluid cracking catalysis (FCC) have a serious detrimental effect on the catalysts physicochemical properties (1-21). Vanadium (at levels < 2,000 ppm) generally yield less hydrogen and coke than nickel contaminants in FCC s and its deleterious effects depend on its concentration and... 

Catalyst Physicochemical properties Substrate Metal oxide characteristics References... 

Water in an ionic liquid may be a problem for some applications, but not for others. However, one should in all cases know the approximate amount of water present in the ionic liquid used. Moreover, one should be aware of the fact that water in the ionic liquid may not be inert and, furthermore, that the presence of water can have significant influence on the physicochemical properties of the ionic liquid, on its stability (some wet ionic liquids may undergo hydrolysis with formation of protic impurities), and on the reactivity of catalysts dissolved in the ionic liquid. 

Table 1 shows that the physicochemical properties of the support material were modified by the pre-treatment process. The particle sizes. Dp, which are summarized in the Table 1 were calculated from the X-ray diffraction patterns of prepared catalysts and a commercial catalyst(30 wt% Pt-Ru/C E-TEK) by using Scherrer s equation. To avoid the interference from other peaks, (220) peak was used. All the prepared catalysts show the particle sizes of the range from 2.0 to 2.8nm. It can be thought that these values are in the acceptable range for the proper electrode performance[7]. For the prepared catalysts, notable differences are inter-metal distances(X[nm]) compared to commercial one. Due to their larger surface areas of support materials, active metals are apart from each other more than 2 3 times distance than commercial catalyst. Pt-Ru/SRaw has the longest inter-metal distances. 

The physicochemical properties of Schiff-base complexes encapsulated in zeolite70 and the surface chemistry of zeolite-encapsulated CoSalen and [Fe(bpy)3]2+ catalysts were studied and published.71... 

Metal nanoparticles have been actively synthesized for applications as catalysts, sensors, adsorbents, analytical probes and optical data storages [1-7]. This is due to the fact that the physicochemical properties of metal nanoparticles can be... 

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. 

An increase in the zeolite crystallites size would very likely produce substantial changes in the physicochemical properties of the catalyst and consequently on the selectivity for hydroisomerisation. Since the effect of the zeolite crystallites size in the nanoscale range cannot be predicted theoretically, n-hexadecane hydroisomerization was carried out on PtHBEA catalysts with different zeolite crystallites sizes. 

At the mesoscopic scale, interactions between molecular components in membranes and catalyst layers control the self-organization into nanophase-segregated media, structural correlations, and adhesion properties of phase domains. Such complex processes can be studied by various theoretical tools and simulation techniques (e.g., by coarse-grained molecular dynamics simulations). Complex morphologies of the emerging media can be related to effective physicochemical properties that characterize transport and reaction at the macroscopic scale, using concepts from the theory of random heterogeneous media and percolation theory. 

Unlike in radical or anionic polymerizations, in ROMP with single-component metathesis catalysts the growing polymer chain remains able to further grow even after consumption of the monomer. This enables the manufacture of block copolymers with interesting physicochemical properties by sequential addition of different monomers to such living systems. 

Steam is invariably present in a real exhaust gas of motor vehieles in relatively high concentration due to the fuel combustion. The influence of water vapor on catalytic performances should not be ignored when dealing with the aim to develop a practical TWCs. Cu/ZSM-5 catalysts once were regarded as suitable substitutes to precious metal catalysts for NO elimination[78], nevertheless, they are susceptible to hydrothermal dealumination leading to a permanent loss of activity[79], Perovskites have a higher hydrothermal stability than zeolites[35]. Although perovskites were expected to be potential autocatalysts in the presence of water[80], few reports related to the influence of water on the reactants adsorption, the perovskite physicochemical properties, and the catalytic performance in NO-SCR were previously documented. The H2O deactivation mechanism is also far from well established. 

Physicochemical Properties of Alumina Supported Silver Catalysts and Their Supports... 

Table 12. Physicochemical properties of alumina-based catalysts [110]...

When the zeolite surface area is plotted as a function of catalytic coke the correlation improves. The best correlation between the physicochemical properties of the catalyst and catalytic coke is the one involving an amount of aluminums in the framework estimated from the unit cell size by Equation 10.1 [1], as it is evidenced in Figure 10.2. 

A feasibility study on the application of H-NMR petroleum product characterization to predict physicochemical properties of feeds and catalyst-feed interactions has been performed. The technique satisfactorily estimates many feed properties as well as catalyst-feed interactions to forecast products yield. There are, however, limitations that have to be understood when using the H-NMR method. The technique, in general, is not capable either to estimate the level of certain contaminants such as nitrogen, sulfur, nickel, and vanadium when evaluating feed properties or the effect of these contaminants on products yields while testing catalyst-feed interactions. 

Recently, we reported that an Fe supported zeolite (FeHY-1) shows high activity for acidic reactions such as toluene disproportionation and resid hydrocracking in the presence of H2S [1,2]. Investigations using electron spin resonance (ESR), Fourier transform infrared spectroscopy (FT-IR), MiJssbauer and transmission electron microscopy (TEM) revealed that superfine ferric oxide cluster interacts with the zeolite framework in the super-cage of Y-type zeolites [3,4]. Furthermore, we reported change in physicochemical properties and catalytic activities for toluene disproportionation during the sample preparation period[5]. It was revealed that the activation of the catalyst was closely related with interaction between the iron cluster and the zeolite framework. In this work, we will report the effect of preparation conditions on the physicochemical properties and activity for toluene disproportionation in the presence of 82. ... 

Three Fe supported zeolites were prepared by modifying NH Y with 0.25M Fe(N03)3 at various temperatures from 293K to 373K, Figure 2 shows the influence of preparation temperature on physicochemical properties and catalytic activity of the obtained catalysts. 

As described above, it was found that physicochemical properties of the iron cluster supported on zeolite and the catalytic activity for toluene disproportionation were significantly affected by the preparation conditions. The catalyst which was prepared by modifying NH Y with 0.25M Fe(N03)3 solution at 323K showed the highest activity among the samples obtained. 

Several preparation methods have been reported for the synthesis of TS-1. In this work, we have investigated the physicochemical properties of TS-1 samples synthesized by different preparation metiiods and tested these materials as catalysts for the oxidation of n-octane, 1-hexene and phenol using aqueous hydrogen peroxide (30 wt%) as oxidant at temperatures below 100 C. For comparison, Ti02 (anatase) and the octahedral titanium-containing silicate molecular sieve (ETS-10) (5) have been studied. The effect of the presence of aluminum and/or sodium on the catalytic activity of TS-1 is also discussed. 

Table 1. Physicochemical properties of the catalysts used in this work...

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