C−C Bond Scission in Ethane Hydrogenolysis

Abstract

C−C bond scission steps are often considered rate-determining in ethane hydrogenolysis. This paper is devoted to the calculations of the activation energies of these steps using the unity bond index−quadratic exponential potential method, formerly known as the bond-order conservation−Morse potential method. Binding energies of atomic carbon with groups VIII and IB metals Ni(111), Pd(111), Pt(111), Rh(111), Ru(0001), Ir(111), Fe(110), Cu(111), and Au(111) are estimated from experimental data on the chemisorption of various species on these surfaces. The resulting estimates are corrected taking into account DFT data on CH x binding energies. The strengths of carbon binding to the surfaces allow arranging the metals into the following series: Cu(111) < Au(111) < Pd(111) < Ru(0001) < Pt(111) ≈ Ni(111) < Rh(111) < Ir(111) < Fe(110). The values of carbon binding energies range from 122.9 kcal/mol for Cu(111) to 192.5 kcal/mol for Fe(110). The activities of these surfaces toward C−C bond scission increase in the same series.