The kinetics of vapor phase benzene hydrogenation reaction on a commercial nickel catalyst was studied in an internal recycle gradientless reactor under atmospheric pressure. The molar ratio of hydrogen to benzene was varied between 6.0 and 18. The temperature range investigated was 90℃-180℃. The catalyst loading of liquid benzene was 1-46 ml/h·g-cat. Assume that there are two kinds of sites on the catalyst surface

benzene vapor adsorbs on one type of site X and hydrogen dissociate upon adsorption on another

say S. Reaction scheme consists of the following steps: Assume that the third step is the rate determining step

and hydrogen are weakly adsorbed on the surface

the intrinsic kinetic equation of cyclohexane formation is derived as follow: where pB and pH are the partial pressures of benzene and hydrogen respectively

k is rate constant and bB

the adsorption equilibrium constant of benzene. The experimental results fitted in this equation with an average absolute deviation of 6.1% The activation energy of reaction was found to be equal to 1.31×104 cal/ mol

and the heat of adsorption of benzene 9840 cal/mol

which are close to the values from literature.