A first principles analysis of the hydrogenation of C1C4 aldehydes and ketones over Ru(0Â 0Â 0Â 1)

► Selective hydrogenation of ketones/aldehydes proceeds by alkoxy and hydroxy mechanisms. ► Alkyl substituents on carbonyl increase barriers for hydrogenation up to 20 kJ/mol per substituent. ► Ketone/aldehyde chain length effects on the selective hydrogenation are small. ► Activation energies for hydroxy path linearly correlate with aldehyde/ketone adsorption energies. ► Activation energies for alkoxy path are insensitive to reactant structure.