OP-II-3

OP-I-17Selectivity (mol. %)10099989796181 C161 C140 C120 CFig. 1. Phenol selectivityfor cyclohexanonevs phenol conversion.Line is the result ofcalculations (Eq. 2).Points are theexperimental data.950 20 40 60 80 100Conversion (mol. %)Supposing all the routes proceed at the same sites, expressions for the routerates will be identical at a high excess of hydrogen. A set of equations forcyclohexanone and cyclohexanol formation rates will look asdx= kΣ(1−x) ⋅f(c)dτdyk1(1 x) f (c) k2y f (c)d τ= − ⋅ − ⋅(1)where x is the phenol conversion, y is the yield of cyclohexanone, k Σ = k 1 + k 3 is thetotal rate constant of phenol conversion over routes 1 and 3, k 2 is the rate constantover route 2, and f(c) is a function of the reaction components concentrations thatdetermines the stationary concentrations of intermediates on the catalyst surface.Integration of the set of equations givess 0bs = ⋅[(1−x) −(1−x)]x(1−b)(2)Selectivity (S) is determined by two parameters, s 0 = k 1 /k Σ and b = k 2 /k Σ , whichdepend on the catalyst properties.As seen from Figure 1, the experimental dependences of selectivity onconversion are satisfactorily described by equation 2. The selectivity is temperatureindependent (in coordinates x – S), which is an essential feature of this catalyst.Reaction rate is described by the first order equation with respect to phenol.Activation energy for all the routes was 51 kJ/mol. Taking into account kineticcharacteristics, a maximum yield that can be attained on this catalyst is 95.3% atphenol conversion 99.2%. A comparison with the known catalytic systems was made.AcknowledgementsWe sincerely thanks Russian agency of science and innovation for financial support (contract numbers02.740.11.0145; 02.740.11.5104, 02.552.11.7075).69