Physical Adsorption - Substitutive Desorption

Reproduced from Czechoslovak Journal of Physics, 49 (Suppl l/II), Lebedev VYa, Yakushev AB, Timokhin SN, Vedeneev MB, Zvara I, 589-595, 1999, with permission of the Institute of Physics, Academy of Sciences of the Czech Republik. 

the process is seen as physical adsorption with subsequent substitutive desorption. The characteristic time of the reaction could be roughly evaluated from the ratio of areas of the two peaks as 45 15 s ( rr). It indicates an activation energy of the reaction of 80 kJ mol-1 or so. The enthalpy of the gaseous chlorination of W02C12 is -40 kJ mol-1 and an estimate for the adsorption enthalpy of W02C12 is about -lOOkJ mol-1 these three values are consistent with the proposed mechanism. The reason why the chlorination does not proceed in gas, though, is its quite exothermic may be the short time, not more than 0.1 seconds. 

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