THE STRUCTURE AND ACTIVITY OF SILICA-SUPPORTED PALLADIUM COBALT ALLOYS .2. SKELETAL REACTIONS OF N-HEXANE AND METHYLCYCLOPENTANE OVER PD-CO/SIO2 CATALYSTS

n-Hexane and methylcyclopentane conversions appeared to be very useful tools for probing surfaces of bimetallic Pd-Co composites supported on silica. Very large changes in activity and selectivity constitute a good basis for diagnosing the extent of interaction between two metal components. The overall activity of cobalt is much higher than that of palladium; in particular, Co predominantly promotes hydrogenolysis of hydrocarbons, whereas other, nondestructive reactions are preferred over Pd and the Pd-richest alloy. A variety of information offers several "fingerprint-like" parameters which enable one to characterize additional properties of these composition regions (i.e., the range of 25-75 at% Co) as compared to neopentane conversion [Part I (W. Juszczyk, Z. Karpinski. D. Łomot, J. Pielaszek. Z. Paál, and A. Yu. Stakheev, J. Catal. 142, 617 (1993)] This work confirms our earlier conclusions that the employed preparation method (incipient wetness coimpregnation technique) produces well-mixed Pd-Co alloy catalysts. Individual Pd-like properties promoting C5-cyclic skeletal reactions (ring closure, isomerization) arc observed up to 25% Co content only. © 1993 by Academic Press, Inc.