Catalysis over coprecipitated nickel-alumina. Effect of nickel content on the hydrogenation of benzene

Abstract

A study has been made of the effect of nickel content on the surface area of the metal and on the kinetics of the hydrogenation of benzene to cyclohexane for five coprecipitated nickel alumina catalysts containing 5.4–75.0 wt % nickel. From a study of the hydrogen adsorption isotherms in the temperature range from –196 to 55°C it was assumed the surface of the metal was saturated with dissociatively adsorbed hydrogen at ambient temperature. The specific activity, i.e., the reaction rate per unit area of nickel, the apparent activation energy, and the reaction orders were measured in the temperature range 0–70°C in a differential flow reactor. The orders of reaction were approximately zero with respect to benzene and 0.6 with respect to hydrogen. Cyclohexene was not detected in the effluent gases. The specific activity, apparent activation energy, and pre-exponential factor for the catalysts were essentially the same. The results are in general agreement with those reported for an evaporated nickel film.