Fig. 8: Illustration of proposed formation routes of carbonylated intermediates.

a The formation of surface acetate and methyl acetate from surface-methoxy species and two acetone production routes: b by direct conversion of ketene via keto-enol tautomerization as well as c initial hydrogenation of ketene to acetaldehyde and diacetyl from acetone, conducted on FER models, with reaction energies (in violet) presented as -(Er) in kJ/mol.