Fig. 4: Analysis of cleavage routes over 2.5, 2.5Ru5Ni and 5Ni catalysts.
Temperature programmed surface reaction of heptane as surrogate for HDPE on (a) 2.5Ru, (b) 2.5Ru5Ni, and (c) 5Ni after hydrogenolysis of HDPE100 with signals corresponding to methane (m/z 16), propane (m/z 44) and hydrogen (m/z 2). Dashed lines indicate onset temperatures. Reaction paths computed via DFT for the cleavage of heptane on (d) Ru, (e) RuNi, and (f) Ni models. Schematic energy profiles are shown for the key steps. Steps with reaction energies ΔE ≤ – 0.3 eV are marked in green (exothermic), steps with 0.3 eV > ΔE > – 0.3 eV are depicted in black (thermoneutral), and steps with ΔE ≥ 0.3 eV or high activation energies Ea ≥ 1.6 eV are marked in gray (blocked). Dashed circles indicate species from which hydrogenation into final products occurs. Additional information is provided in Supplementary Figs. 33–36. Ru: blue, Ni: brown.
