Hydrogenolysis apparent activation energy

Table V. Ethane hydrogenolysis apparent activation energies and turnover numbers giving a comparison between Os cluster-derived materials and metallic 0s/Si02.

Figure 13. Dependence of ethane hydrogenolysis TOF and apparent activation energy on Pt particle size. TOFs decrease by two orders of magnitude over the size range, while the apparent activation energy increases. Coordinatively unsaturated surface atoms in small particles have a higher reactivity and subsequently a smaller barrier for hydrogenolysis than highly coordinated surface atoms of larger particles. TOFs were measured at 20 Torr C2H6, 200 Torr H2, and 658 K [16]. (Reprinted from Ref [16], 2006, with permission from American Chemical Society.)...

Table 5 Hydrogenolysis of AcOBu on lRelPt(e,red) catalyst in SPR16 reactor. Reaction order for AcOBu and apparent activation energy.

Fig. 5. Apparent activation energies of the ethane hydrogenolysis and cyclopropane hydrogenation reactions on the group VIII noble metals. The activation energies were determined at hydrogen and hydrocarbon partial pressures of 0.20 and 0.030 atm, respectively (63).

In addition to the correlation between the order in Ph2 and Eapp, the compensation effect is regularly observed for hydrogenolysis reactions48 50. The compensation effect denotes a linear relationship between the apparent activation energy and the pre-exponential factor. This relationship is also called the Constable-Cremer relation51 ... 

Figure 7.5. Compensation effect for the hy-drogenolysis reaction. The logarithm of the preexponential factor is plotted against the apparent activation energy, A , for this reaction over several transition-metal catalysts. The squares, triangles, and circles represent values for ethane, methylamine, and methyl chloride hydrogenolysis, respectively [1881.

TABLE 13.1. Apparent Activation Energies (kJ mol ) for Hydrogenolysis (Eh) and for Isomerisation Ei) of the Lower Alkanes... 

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