Theory of Methane Dehydrogenation on Pt{110}(1 × 2). Part II:  Microscopic Reaction Pathways for CHx→ CHx₋₁(x= 1−3)

Microscopic reaction pathways for the transformation of chemisorbed methyl to atomic carbon on Pt{110}(1 × 2) have been identified using calculations based on density functional theory in combination with a constrained minimization technique. For CH 3 and CH 2 dehydrogenation, calculated activation energies of 0.34 eV (33 kJ mol -1 ) and 0.56 eV (54 kJ mol -1 ) are obtained, respectively. For CH dehydrogenation, the calculated activation barrier of 1.20 eV (116 kJ mol -1 ) is in excellent agreement with the experimentally determined barrier of 1.25 eV (121 ± 3 kJ mol -1 ). 1 The resulting calculated reaction-energy profile for the conversion of CH 3 to CH and ultimately carbon on Pt{110}(1 × 2) is reported and discussed in terms of previous experimental results obtained for this system.