Catalytic Activity of Powdered Tantalum Carbide for Hydrogenation of Benzene

Abstract

Hydrogenation ef benzene catalyzed by powdered tantalum monocarbide, which is known as a refractory material, was investigated at 25. v2800C by use of a microreactor.The activity of tantalum carbide (TaC) was negligibly when evacuated at temperatures lower than 9000C, but it greatly increased by the evacuatien above 1000C. The surface area measured by krypton gas adsorpti was nearly constant(1.5 m2/9)regardless of the evacuation tempature, Carbon monoxide or exygen preadsorbed on thus-activated catalyst was found to depress the activity, which became zero by the addition of around 3 iee mole of oxygen per gram catalyst. This value shows that around 60%e of total surface area is effective as active sites, The catalyst poisoned with carbon monexid or oxygen was, however, completely reeovered by the evacuation'tat around 700 or 10000C, respeetevely.These results suggest that the catalytic activation of powdered tantalum carbide produced by the evacuation at 10000C is attributable to the elimination of oxygen atoms