Fig. 4: Thermodynamic cycle for the gas- and aqueous-phase adsorption of furfural (F) on Pd.
From: Impact of hydronium ions on the Pd-catalyzed furfural hydrogenation
A replacement ratio of 6.5 water molecules by one furfural molecule on Pd is used. Ultrahigh vacuum above the clean Pd surface is denoted as UHV/Pd. For simplicity, the difference between bond energy (∆U) and enthalpy (∆H) in gas-forming steps is considered negligible (∆U = ∆H + RT, and RT = 2.5 kJ mol−1 at 298 K is omitted). a Solvation enthalpy calculated using the van’t Hoff equation and Henry’s law constant27,28. b Enthalpy of adsorption of water on Pd (see Supplementary Note S1). c Enthalpy of saturated adsorption in aqueous phase measured by liquid colorimetry. d Computed adsorption enthalpy at 0.25 ML and e at 0.5–1 ML in UHV from ref. 20.
