MCET

Commercial plants Approximately 40% of the world s ethylene plants use Lummus ethylene technology. Many existing units have been significantly expanded (above 150% of nameplate) using Lummus MCET (maximum capacity expansion technology) approach. 

Driving Eorce Dependence of MCET Rate Constants / 115... 

III. METAL ION COUPLED ELECTRON TRANSFER A. Intermolecular MCET... 

The ET rates obeyed second-order kinetics, showing a first-order dependence on the concentration of each reactant [O2 and (TPP)Co] (69). The observed second-order rate constant (/robs) for the M" promoted ET increases finearly with increasing metal ion concentration (69). This indicates that the binding of M"" " to O2 is coupled with ET when M " " promoted ET occurs in a concerted manner (MCET) rather than a stepwise manner. If the rate-determining step were a uphill ET from (TPP)Co to O2, followed by rapid binding of M" to 02 , the ET rate would be independent of metal ion concentration. 

Rates of M"" -promoted ET from electron donors to acceptors normally increase linearly or approach limited values with increasing concentration of M" (see below) (6-10). In contrast, self-organized MCET systems involving multiple molecular environment can lead to decreases of entropy equivalent to an increase of molecular electronic order for the activated complex, resulting in a substantial increase in the rate of ET (98,99). In such a case, the rate of ET is no longer linearly related to concentrations of reactants and promoting molecules for ET. New frontiers of ET may be exploited in such nonlinear dynamic and self-organized... 

MCET systems that Nature has developed to a high degree of perfection (15). In the... 

The applicability of the Marcus equation (Eq. 14) to MCET reactions was examined using a ferrocene-naphthoquinone dyad (Fc—NQ) as discussed below (Scheme 19)(121,122). No ET from the Fc to NQ moiety occurs in Fc—NQ with a... 

As demonstrated above, the driving force dependence of / et of the metal ion-promoted intramolecular ET can be evaluated well within the context of the Marcus theory of ET. Here the driving force of MCET increases with increasing concentrations of metal ions, whereas the reorganization energy of MCET decreases with concentrations of metal ions. 

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