Catalyst number

Catalyst number First scenario Second scenario ... 

Catalyst number Third scenario Fourth scenario... 

Fig. 18 Reaction rate of hydrolysis of p-nitrophenyl acetate as a function of inverse temperature. Thermosensitive imidazole-containing copolymers (PVCL-Vim, PNIPA-Vim), 1-methylimidazole and poly(l-vinylimidazole) act as catalysts. Numbers in the copolymer abbreviations denote the Vim content (in mole percent). Vim 1-vinylimidazole. (Adapted from Ref. [18])...

Test Catalyst number Total Previous days of treatment4 synthesis Pres- sure atmos- pheres Tem- pera- ture. °C. Space velocity Con- trac- tion, per- cent Phases Atom ratios to iron Percentage of iron as ... 

Catalyst Number of mmols of catalyst 1-Hexene conversion %t % of 1-Hexene converted into aldehydes" Internal olefins, mmol [%f 1-Heptanal, mmol Internal aldehydes, mmol Selectivity Number of turnovers ... 

The analysis of the catalytic oxidation of SO2 developed previously in this chapter, can be completed as follows (i) the experiments with catalysts number 2 and number 6 are eliminated (ii) new experiments are introduced in order to consider the temperature as a process factor. All the other factors of the catalytic process keep the values from Table 5.40. In Table 5.43 we present a new set of experimental results in order to obtain more knowledge of the effect of the type of catalyst and the temperature on the degree of oxidation. The correspondence between the different types of catalysts reported in Tables 5.43 and 5.40 are respectively 1 1, 2 3, 3 4, 4 5. As has been explained above, the inlet gas composition, the gas flow rate and the length of the catalytic bed remain unchanged for all experiments, the last limitation is imposed in order to obtain the smallest errors in the measurements for the process response [5.32]. 

We can observe in Table 5.43 that the maximum yield is obtained with catalyst number two (X2 = 2), the response obtained with this catalyst can be analyzed deeply with respect to other process parameters such as the input reactor gas flow rate and the temperature. Two different values or levels of these parameters will be considered whereas other parameters or factors will remain constant (Table 5.40). Table 5.47 gives the experimental data after the arrangement required by Table 5.45 together with the partial and total mean values of SO2 oxidation degree. 

Starting cluster Amount of L (no. of equiv.) Amount of catalyst (%) Number, n, of ligand(s) in the final product Stability of products in solution... 

Fig. 12.5. Dependence of the rate of styrene hydrogenation on the Aq of the nickel catalysts listed in Table 12.2. The numbers in the figure correspond to the catalyst numbers in this table. (Redrawn using data from Ref. 129.)...

Catalyst Number of polymers Glutamic acid (pmoles formed in 1 hour)... 

Catalyst number Si/Ti (AAS) Si/Ti (XPS) Ti/unit cell (in product) Al/unit cell (after dealumination) Ti02 Raman signal... 

FIGURE 19.6 Electronic energy as a function of the reaction coordinate for the epoxidation of styrene using a Mn-porphyrin catalyst. Numbering of the transition states (TS) corresponds to the steps in Fig. 19.4. 

The results obtained in the present work indicate that the method used for the catalyst preparation leads to some changes in the characteristics and performance of the obtained catalytic formulations. These changes are due to differences in the characteristics of both the deposited metallic species (their coordination state, location and dispersion) and the contribution of the acidic component of the catalyst (number of accessible acid sites and partial destruction of zeolite structure). Therefore, the importance of the method used for the preparation of zeolite-containing catalysts is clearly observed. 

Fig. 5. XPS plots, a - cobalt, b - oxygen. 1,2,3 - catalysts numbers in table 1.

For the selection of the final production process ecological, economical, and technical aspects were compared. Criteria for the route-selection were catalyst activity, stability and storage properties of the catalyst, number of reaction steps of the different processes, concepts of metal recovery and recycle, safety aspects of the coupling reactions, and other more. 

Catalyst number Eelative amount adsorbed (Aneq) (Total = 1.0 for each catalyst Kate constant (reciprocal time)... 

Catalyst Number of adsorbed methanol molecules/surface V atom... 

The variable 6a in equation 8 is the product of the fractional surface coverage and the catalyst number, ou The catalyst number is the ratio of the total number of moles of active centers and the number of moles of gas A in the inlet pulse, or the number of active centers per molecule of gas A in the inlet pulse. In a typical TAP-2 pulse response experiment, the amount of catalyst sample, such as a metal or metal oxide, is =10 g, the total number of active sites is usually between 10 " to 10, and the number of molecules in a pulse is a 10. Thus, in a typical TAP-2 pulse response experiment, the catalyst number is = 10 to 105. 6a is called the pulse-normalized dimensionless surface concentration, and is described by... 

X - conversion of gas A z = axial coordinate (cm) a = catalyst number defined by equation 9 5 = delta function... 

Saturated complex polyethers, particular polybutylenetherephtalate (PBT), are used as enginiring thermoplasts, having a good thermo- and wear stability, excellent performance. These properties allow also to apply them as a matrix material for polymer composites One of the perspective ways of effective filler-catalysts searching is kinetic study of reetherification model reaction, performed in the presence of various inorganic compoimds. The elucidation on the example of model system of the most effective filler-catalysts number allows to use them for receiving filled PBT and compare catalytic activity of filler and traditional catalysts. 

Fig. 8 Catalytic activity of N2O decomposition on various catalysts. (Number indicated on the bars are reaction temperature in C)...

Krilov OV, KisUev VF (1981) Adsorption and catalysis on the transition metals and their oxides. Chemistry, Moscow Kroger FA, Vink HJ (1956) Relations between concentrations of imperfections in crystaUine solids. In Seitz F, TumbuU D (eds) Solid state physics, vol 3. Academic, New York, pp 307-435 Kulkami D, Wachs IE (2002) Isopropanol oxidation by pure metal oxide catalysts number of active surface sites and turnover frequencies. Appl Catal A 237 121-137 Kulwicki BM (1991) Humidity sensors. J Am Ceram Soc 74 697-708... 

Obviously, the intention of manufacturing highly porous catalyst particles is to create a large internal surface where reaction can take place. Therefore, the reaction rate per unit volume of catalyst can be very high. However, the actual conversion rates are often limited by rates of transport processes. There are at least two relevant mass transport mechanisms the external mass transfer and the internal diffusion. The rate of internal diffusion cannot be separated from the reaction rate they enhance each other. This has been treated in some detail in section 5.4.3. The combined effect of both "resistances is shown in eq. (5.51). To get an idea which of the two resitances prevails, one can define the dimensionless catalyst number Ca as the ratio between the two terms in the denominator in eq. (5.51) ... 

The catalyst number Ca is a property of the catalyst in a given situation it indicates the ratio of internal and external rate constants. When Ca 1, the reaction and diffusion in the catalyst particle determine the rate of the process when Ca 1, external mass transfer is rate determining. When Ca is not very much different from 1, both resistances have to be taken into account. This is the case in many practical situations. If Ca were 1, it would be worth while to increase the mass transfer coefficient, either by increasing the fluid flow rate or by taking smaller particles. If Ca were 1, it would be worth while to increase the reaction rate per unit of external particle surface, either by raising the temperature, or by taking larger particles. 

Reactions with solid catalysts are often carried out under conditions of high reactivity. Therefore, as a rule, both external and internal transport rates are rate determining to a certain extent, depending on the value of the catalyst number Ca. This determines in principle the optimum particle size of the catalyst, with respect to the amount of catalyst required. Obviously, for practical reasons one may prefer a different particle size. Particularly when there are severe heat transfer requirements, a fine suspended catalyst may be desirable. 

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