Ethane, hydrogenolysis, activity

Fig. 6. Activities of copper-nickel alloy catalysts for the hydrogenolysis of ethane to methane and the dehydrogenation of cyclohexane to benzene. The activities refer to reaction rates at 316° C. Ethane hydrogenolysis activities were obtained at ethane and hydrogen pressures of 0.030 and 0.20 atm., respectively. Cyclohexane dehydrogenation activities were obtained at cyclohexane and hydrogen pressures of 0.17 and 0.83 atm, respectively (74).

Figure 3.2 Hydrogen chemisorption capacity and ethane hydrogenolysis activity of ruthenium-copper aggregates as a function of copper content (3). (Reprinted with permission from Academic Press, Inc.)...

The copper also strongly suppresses the catalytic activity of ruthenium for the hydrogenolysis of ethane to methane, as shown by the data in the lower field of Figure 3.2. The ethane hydrogenolysis activities are reaction rates measured at 245°C and ethane and hydrogen partial pressures of 0.030 and 0.20 atm, respectively. 

The incorporation of only 1.5 at.% copper decreases the amount of strongly chemisorbed hydrogen by about 60% and lowers the activity for ethane hydrogenolysis by three orders of magnitude. With further increases in the amount of copper, the hydrogen chemisorption capacity and ethane hydrogenolysis activity continue to decrease markedly. 

The exponential nature of the relation in Figure 3.4 is a clear indication that ethane hydrogenolysis activity is much more sensitive to variations in... 

Figure A3.10.20 Arrhenius plot of ethane hydrogenolysis activity for Ni(lOO) and Ni(l 11) at 100 Torr and H2/C2Hg = 100. Also included is the hydrogenolysis activity on supported Ni catalysts at 175 Torr and... 

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.)...

Fig. 1. Catalytic activities of metals for ethane hydrogenolysis in relation to the percentage d character of the metallic bond. The closed points represent activities compared at a temperature of 205°C and ethane and hydrogen pressures of 0.030 and 0.20 atm, respectively, and the open points represent percentage d character. Three separate fields are shown in the figure to distinguish the metals in the different long periods of the periodic table.

Fig. 4. Comparison of activity patterns of the group VIII noble metals for cyclopropane hydrogenation and ethane hydrogenolysis. The activities were all determined at hydrogen and hydrocarbon partial pressures of 0.20 and 0.030 atm, respectively (63).

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