Oxidative
methanol dehydrogenation is a major industrial reaction
with global formaldehyde production exceeding 30 million tonnes per
year. Unfortunately, oxidative dehydrogenation produces water–aldehyde
mixtures that require subsequent distillation. Anhydrous alcohol dehydrogenation
is a promising alternative that produces H2 instead of
water. Pursuant to recent experimental work showing that highly stepped
Cu(111) surfaces exhibit anhydrous dehydrogenation activity, we present
first-principles density functional theory calculations for methanol
and ethanol dehydrogenation at Cu(111) step edges to provide an atomistic
understanding of the catalytic mechanism; these sites stabilize all
intermediates while reducing activation energies. We find that van
der Waals contributions to the energy account for more than 50% of
adsorption energies, and their inclusion is essential in achieving
good agreement with experimental desorption temperatures. Furthermore,
vibrational zero-point energy corrections significantly reduce the
activation energy for all reaction steps considered here. Hydrogen
bonding among ethanol intermediates at step edges is weakened by geometric
frustration. These insights lead us to propose several suggestions
for further research on undercoordinated Cu sites as anhydrous alcohol
dehydrogenation catalysts.