Catalytic turnover frequency

Figure 1.3. Rate and catalyst potential response to step changes in applied current during C2H4 oxidation on Pt deposited on YSZ, an O2 conductor. T = 370°C, p02=4.6 kPa, Pc2H4=0.36 kPa. The catalytic rate increase, Ar, is 25 times larger than the rate before current application, r0, and 74000 times larger than the rate I/2F,16 of 02 supply to the catalyst. N0 is the Pt catalyst surface area, in mol Pt, and TOF is the catalytic turnover frequency (mol O reacting per surface Pt mol per s). Reprinted with permission from Academic Press.

The equilibrium constant K for (por)Fe(OH2) (por)Fe, which determines the molar fraction of the 5-coordinate redox-active Fe catalyst. This constant was estimated from analysis of the catalytic turnover frequencies in the presence of varying concentrations of an inhibitor, CN, which competes with both O2 and H2O for the 5-coordinate Fe porphyrin. 

In addition to the rate acceleration observed, the technique of rapid mixing and heating afforded an unprecedented catalytic turnover frequency of 4.3 x lCrh-1. Using this approach, the authors subsequently investigated the C-C coupling reactions between phenyl acetylene 32 and a further nine aryl halides to afford yields ranging from 62 to 100%. 

In this paper we will provide another example of the occurrence of a maximum catalytic turnover frequency for a specific composition of the faujasite catalysts. We also will present further evidence that for every Bronsted acid catalysed reaction in H-faujasites, this is the generally expected behaviour and will introduce a new concept to rationalize this. 

Figure 1. Literature data on the evolution of the catalytic turnover frequency (TOF) per framework aluminum site of H-faujasite (a), cumene cracking (4) (b), hexane cracking (6) and (c), cumene cracking (3). ...

The catalytic turnover number (TON) is the number of moles of product per mole of catalyst this number indicates the number of catalytic cycles for a given process, e.g. after 2 h, the TON was 2400. The catalytic turnover frequency (TOP) is the catalytic turnover per unit time the number of moles of product per mole of catalyst per unit time, e.g. the TOF was 20min. ... 

Defining the catalytic turnover number and frequency is not without problems. For example, if there is more than one product, one should distinguish between values of the total TON and TOF for aU the catalytic products, and specific values for individual products. The term catalytic turnover number is usually used for batch processes, whereas catalytic turnover frequency is usually apphed to continuous processes (flow reactors). 

Early in the development of the field there were hopes that unsupported nanoparticles stabihzed with surfactants and/or organo-aluminum-sheUs in Hquid phases should work as soluble surfaces exhibihng very high catalytic turnover frequencies associated with reasonable lifetimes and, potentially, be recyclable [8-10,104, 105]. 

The catalytic turnover frequency (TOF) is the catalytic turnover per unit time the number of moles of product per mole of catalyst per unit time, e.g. the TOF was 20min . ... 

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