CO tolerance of a Pt3Sn(111) catalyst in ethanol decomposition

Abstract

CO tolerance is one of the crucial factors to protect catalysts against inactivation during ethanol decomposition processes. Herein, the intrinsic essence of CO tolerance and the effect of the alloying element Sn in Pt₃Sn(111) are investigated by combining periodic density functional theory (DFT) and microkinetic modelling. It is found that the most competitive route to CO proceeds via CH₃CH₂OH → CH₃CH₂O → CH₃CHO → CH₃CO → CH₂CO → CH₂ + CO. Resulting from the decomposition of easily-oxidized CH₃CO and hard-forming but readily-desorbed CH₂CO, and the less competitive C–C bond scission occurring before C^α–H, C^β–H, and O–H bond scission, the formation of CO is not facile on Pt₃Sn(111). The alloying element Sn plays “bifunctional” and “ligand effect” roles to effectively strengthen O-end species adsorption, adjust the alloy electronic structures and weaken the Pt–CO bonds, thus facilitating CO elimination from Pt₃Sn(111). Microkinetic modelling confirms the substantially high CO tolerance of Pt₃Sn, and easy desorption of the most abundant species such as CH₂CO and CH₂ from the surface above room temperature. This theoretical work sheds new light on the CO tolerance of Pt₃Sn(111) in ethanol decomposition and provides a fresh perspective on understanding the effect of alloying elements.