Catalyst Properties and Activity

Model formulation. After the objective of modelling has been defined, a preliminary model is derived. At first, independent variables influencing the process performance (temperature, pressure, catalyst physical properties and activity, concentrations, impurities, type of solvent, etc.) must be identified based on the chemists knowledge about reactions involved and theories concerning organic and physical chemistry, mainly kinetics. Dependent variables (yields, selectivities, product properties) are defined. Although statistical models might be better from a physical point of view, in practice, deterministic models describe the vast majority of chemical processes sufficiently well. In principle model equations are derived based on the conservation law ... 

Table 1 Key Properties and Activity of the Delink (Pd/CPS4) vs. Classical Catalysts (Pd/CPS 1 and CPS2), ...

Another sample, after oven drying, was irradiated by microwave radiation from 2 to 20 min. A comparison of the catalyst properties and water-gas shift rates is provided in Table 124. The authors observed important increases in the activity after treatment with sodium borohydride and hydrazine, which they correlated with an improvement in the reducibility (i.e., intensity of low temperature peak in TPR) related to reduction of Au oxide species and partial reduction of Fe oxide. A decrease in the rate for the microwave irradiated catalyst was linked to Au crystallite growth, but the authors indicated that the procedure is still worth exploring, as the technique increased the number of Au species that were reducible at low temperature. 

Characterization is a central aspect of catalyst development [1,2], The elucidation of the structures, compositions, and chemical properties of both the solids used in heterogeneous catalysis and the adsorbates and intermediates present on the surfaces of the catalysts during reaction is vital for a better understanding of the relationship between catalyst properties and catalytic performance. This knowledge is essential to develop more active, selective, and durable catalysts, and also to optimize reaction conditions. 

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. ... 

Methodology In Figure 1 a) and b) the principles of catalytic profiling analysis are explained Catalytic profiling analysis includes a set of test reactions which are very sensitive with respect to catalyst properties and/or the recipes of preparation. From activity and selectivity values measured for a set of test reactions (Fig. la) corresponding performance profiles (Fig. lb)) can be derived which can be understood as catalytic fingerprints for individual catalysts. Thus, performance profiles allow a statistical analysis of similarities (Fig. lb). 

Table VI. Preparation, Properties, and Activity for n-C6 Isomerization of Catalysts Based on Zeolite Omega...

Catalyst preparation and activation conditions are included as parameters of importance in the optimisation algorithm. The preparation and activation procedures are very relevant aspects since minor variations in such conditions would cause major changes to the final phase of the solid and, consequently, to its catalytic properties. Typical preparation variables are promoter precursors, type of impregnation, calcination atmosphere, time and temperature, time and temperature for metal reduction and so forth. 

Although an increase in meso pore surface area and activity will result in an increase in conversion and resid conversion, Table IV also shows that there is no simple correlation between the observed catalyst properties and these results. Apparently other aspects such as pore size distribution and pore chemistry also play an important role. 

Diez, V. K., Apesteguia, C. R. and Di Cosimo, J. I. Acid-base properties and active site requirements for elimination reactions on alkali-promoted MgO catalysts. Catal. Today, 2000, 63, 53-62. 

Catalysts The properties and activities of two commercial HDN catalysts are shown in Table 1. The used catalysts had been used in industrial device for 1.5 years. The operation conditions were temperature 663-668K H2 pressure 17 MPa LHSV- 1 h 1. The feedstock contained 1400 ppm total nitrogen. 

Kohler K, Heidenreich RG, Krauter JGE, Pietsch J (2002) Highly active palladium/activated carbon catalysts for Heck reactions correlation of activity, catalyst properties, and Pd leaching. Chem Eur J 8 622-631... 

In applying the fluidized bed to catalytic reactions, the catalyst must have the appropriate properties and activity. For production of phthalic... 

This paper describes the use of polydentate ligands to optimize the performance of palladium catalysts for CO2 reduction and to probe mechanistic aspects of catalytic reactions. Polydentate ligands can be used to precisely control coordination environments, electronic properties, and specific steric interactions that can lead to new insights into the relationship between catalyst structure and activity. 

Supercritical fluids bring other benefits to solid-catalyzed reaction rate through eliminating or minimizing mass and heat transfer resistances. Supercritical solvents have the ability to regenerate the catalyst during the course of the reaction, which increases the catalyst life and activity, because undesirable deposits on the catalyst, such as carbon deposits, are soluble in the supercritical fluids. The rate of the intrinsic reaction is increased in supercritical fluids and by tuning the properties of the supercritical medium, one can control the selectivity. ° ... 

Influence of the preparation method on the surface properties and activity of alumina - supported gallium oxide catalysts... 

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