I am trying to find out the rate constant and TOF for the Nitrophenol reduction reaction, usually all papers they are not explaining about the method of calculating rate constant and TOF can any one help me?
This paper might be helpful; Kozuch, S.; Shaik, S. Accounts of Chemical Research 2010, 44, 101.
Dear, Gnanaprakasam: Heterogeneous catalysis normally follows a first order kinetic. The rate law for a reaction that is first order with respect to the reactant concentration C is: r = d[C]/dt = - k.C leading to the following integrated equation: ln (Ct/Co) = - k.t where Ct is the reactant concentration at a contact time (time-on-stream), t, and Co is the initial concentration at t = 0. Then, by plotting
ln (Ct/Co) vs. t (1/s) (insert in Fig. 3 of the paper) gives a straight line with a slope of – k, from which the reaction rate, r, expressed as g-mol (transformed reactant) per g (catalyst) per hour can be obtained.
If, on the other hand, you are able to determine the concentration of the active sites (AS) in your catalyst (number of Au–Fe3O4 hybrid NPs per g catalyst), then the turnover number (TN), expressed as the number of molecules undergoing transformation per active sites, can be readily calculated by dividing the reaction rate, r, expressed as molecules of transformed reactant per g of catalyst per hour, by AS (number of active sites per g of catalyst). The number of active sites should be obtained by chemical analysis of Au, assuming that each Au-atom is active (100% disperse). Otherwise, actual dispersion of the active center using characterization techniques such as electron microscopy and/or hydrogen chemisorption have to be used to determine the degree of dispersion.
Dear Xuepeng Zhang sir we don't have the access for that journal can you send me that paper to my mail, my id is [email protected]
See the link: A very useful review explaining TOF
http://image.sciencenet.cn/olddata/kexue.com.cn/blog/admin//images/upfiles/2007101173356109879.pdf
You basically need to know the dispersion of your catalyst.
You can get it theoretically if you know the particle size, but CO or H2 chemisorption give more realistic results (which whould however be coherent with the theoretical ones).
Once you know it, you just devide the reaction rate (mol mol-1 s-1) by the dispersion.
TON is more tricky because it implies the number of transformations during the whole life cycle of your catalyst, so in theory you should wait until the catalyst is no longer active and calculate the mols of reactant transformed per mol of catalyst during that time.
Hi
Can you please find the attached image that shows the equation I used during the calculation of TOF
Have a very good day and best of luck
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