Mechanism for the water-gas shift reaction on monofunctional platinum and cause of catalyst deactivation

作者：Flaherty David W; Yu Wen Yueh; Pozun Zachary D; Henkelman Graeme; Mullins C Buddie^*

来源：Journal of Catalysis, 2011, 282(2): 278-288.

DOI：10.1016/j.jcat.2011.06.024

• Copper
• Noble metal
• Reforming
• Model catalyst
• Poisoning
• Hydrogen
• Reaction mechanism

The behavior of monofunctional platinum, Pt(1 1 1), for the water-gas shift reaction has been investigated using experimental and theoretical methods. Kinetic and isotopic measurements performed from 525 to 675 K are consistent with an associative mechanism for the water-gas shift reaction in which carbon monoxide is oxidized by a hydroxyl group. The kinetically-relevant step consists of the unimolecular decomposition of an adsorbed carboxylate intermediate. The turnover frequency of Pt(1 1 1) is five times greater than that observed on Cu(1 1 1) under identical conditions (612 K, 26 Tort CO, 10 Torr H2O); however, Pt(1 1 1) loses activity over time due to the formation of carbonaceous deposits, a process not observed in similar studies of Cu(1 11). Our experimental and theoretical results suggest that CO dissociates via two pathways: the Boudouard reaction and through a COH intermediate. Nucleation of carbon at step-edges and subsequent oligomerization deactivate the catalyst. These results provide insight into the synergistic roles of noble metal clusters and active supports for the water-gas shift reaction.

• 出版日期2011-9-1