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Local Promotional Rules

When examining the rate dependence on D at any fixed work function O value, two possibilities exist  [Pg.296]

On the basis of the above global promotional mles the following two very simple local (L) rules can be directly derived  [Pg.296]

Rule LI When the electron acceptor reactant (A) is more strongly adsorbed than the electron donor reactant (D) then the reaction exhibits local electrophobic behaviour. [Pg.296]

The local mles LI and L2 can also be expressed in the following equivalent way  [Pg.296]


The above global and local promotional rules suggest, in a straightforward manner, the following three practical rules for promoter selection with respect to rate maximization911 ... [Pg.298]

Tables 6.2 to 6.9 summarize all local (Table 6.2), global (Tables 6.3 to 6.7), fundamental (Table 6.8) and practical (Table 6.9) promotional rules. Tables 6.6 and 6.7 provide some obvious extensions to monomolecular reactions, also in good agreement with experiment. All the rules can be summarized by the inequalities 6.11, 6.12 and 6.13 ... Tables 6.2 to 6.9 summarize all local (Table 6.2), global (Tables 6.3 to 6.7), fundamental (Table 6.8) and practical (Table 6.9) promotional rules. Tables 6.6 and 6.7 provide some obvious extensions to monomolecular reactions, also in good agreement with experiment. All the rules can be summarized by the inequalities 6.11, 6.12 and 6.13 ...
Table 6.2. Local Electrochemical Promotion Rules (Langmuir-Hinshelwood mechanisms)... Table 6.2. Local Electrochemical Promotion Rules (Langmuir-Hinshelwood mechanisms)...
The crucial task remains of examining to what extent it can also describe the effect of promotion, electrochemical or classical, on catalytic reaction kinetics. More specifically we will examine to what extent it can predict the four main types of global r vs O dependence and all the associated local and global electrochemical and chemical promotional rules. [Pg.315]

Metcalfe107,108 has recently modeled electrochemical promotion using 02 conductors and derived108 equation (6.66) using transition state theory and the concept of a partially charged transition state.108 Despite this interesting theoretical study,108 which is consistent with the basic experimental electrochemical promotion observations Eqs. (4.49) and (4.50) little is still known, experimentally or theoretically about the parameter AR and its possible relationship to A and Aa. Consequently, and in order not to introduce adjustable parameters, we will set XR equal to zero in the subsequent analysis and will show" that it is possible to derive all local and global promotional rules in terms of only four parameters... [Pg.316]

The mathematical model of equations (6.63) to (6.65) is in excellent qualitative agreement with experiment as shown in Figures 6.18 to 6.25. It describes in a semiquantitative manner all electrochemical promotion studies up to date and predicts all the local and global electrochemical and classical promotion rules LI, L2 and G1 to G7. [Pg.317]

As shown on this Figure and also in Fig. 8.29 increasing Uwr and O above their open-circuit potential values leads to a local "volcano , i.e. the rate goes through a maximum. This is consistent with the global promotional rule G3 and the observed rate dependence on pco/po2 (Fig- 8.30) where it is interesting to observe that the rate maximum is only moderately affected by the applied potential. [Pg.386]

This is a truly exciting electrochemical promotion system which can serve as an excellent example for illustrating the two local and three of the four global promotional rules described in Chapter 6. The reason is that under open-circuit conditions the reaction is positive order in both reactants, as can be seen in subsequent figures. [Pg.421]

Then analyze Table A. 1 on the basis of the local and global promotional rules of Chapter 6. [Pg.540]

On the basis of the published literature on NEMCA or Electrochemical promotion up to now (2001) there appear to be no exceptions to the above local and global rules. [Pg.291]

Translation Initiation Site. In eukaryotes, if the transcription start site is known, and there is no intron interrupting the 5 UTR, Kozak s rule (Kozak, 1996) probably will locate the correct initiation codon in most cases. Splicing is normally absent in prokaryotes, yet because of the existence of multicitronic operons, promoter location is not the key information. Rather, the key is reliable localization of the ribosome binding site. The TATA sequence about 30 bp from the transcription start site may be used as a possible resource. [Pg.188]

The total electron density contributed by all the electrons in any molecule is a property that can be visualized and it is possible to imagine an experiment in which it could be observed. It is when we try to break down this electron density into a contribution from each electron that problems arise. The methods employing hybrid orbitals or equivalent orbitals are useful in certain circumstances such as in rationalizing properties of a localized part of the molecule. However, the promotion of an electron from one orbital to another, in an electronic transition, or the complete removal of it, in an ionization process, both obey symmetry selection rules. For this reason the orbitals used to describe the difference between either two electronic states of the molecule or an electronic state of the molecule and an electronic state of the positive ion must be MOs which belong to symmetry species of the point group to which the molecule belongs. Such orbitals are called symmetry orbitals and are the only type we shall consider here. [Pg.261]

Of course, this suggests a barrier on the potential energy surface, which prevents further reaction of the complex to form KCl + H. With the classification of Polanyi such a barrier is a late barrier, localized somewhere in the exit channel of the reaction [70, 73], With such a barrier, translational energy is less efficient at promoting the reaction than a comparable increase in the vibrational energy of the HCl reaction partner [269], This anticipation based on the Polanyi rule for barrier location was exactly confirmed by the gas-phase measurements of Brooks and co-workers [123, 124],... [Pg.3049]

Epoxidation of butadiene occurs by addition of dissociatively-adsorbed oxygen to one of the localized C=C bonds to form epoxybutene. The addition of oxygen across the terminal carbon atoms does not occur to any measurable extent. The direct participation of molecular oxygen can be ruled out based both on selectivity arguments as well as the kinetic model for the reaction. The kinetics imply a dual site mechanism. One site, which is unpromoted, serves as the site for butadiene adsorption, while the second site, which is promoted, functions as the site for dissociative oxygen adsorption and epoxybutene formation. [Pg.135]

A bill has been promoted in Congress to allow small-scale treatment by laboratory personnel. Howeva-, specific legislation has not been enacted at this time. The fact that regional EPA offices have interpreted such small-scale reactions differently further complicates decisions at the laboratory level. Because illegal treatment can lead to fines of up to 25,000 per day, it is most important that, before carrying out any processes that could be considered treatment, the responsible laboratory workw or the institution s environmental health and safety office check with the local, state, or regional EPA to clarify its intapretation of the rules. [Pg.149]


See other pages where Local Promotional Rules is mentioned: [Pg.296]    [Pg.296]    [Pg.119]    [Pg.410]    [Pg.748]    [Pg.573]    [Pg.554]    [Pg.367]    [Pg.306]    [Pg.307]    [Pg.346]    [Pg.97]    [Pg.215]    [Pg.425]    [Pg.310]    [Pg.680]    [Pg.200]    [Pg.748]    [Pg.9]    [Pg.14]    [Pg.12]    [Pg.331]    [Pg.68]    [Pg.473]    [Pg.88]    [Pg.148]    [Pg.71]    [Pg.265]    [Pg.7]    [Pg.310]    [Pg.199]    [Pg.7]    [Pg.144]    [Pg.142]   


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