The reactivity and the role of formate species on Low Temperature water-gas shift (WGS, CO + H2O ? CO2 + H2) catalysts and the corresponding reaction mechanisms have been much debated. A major source of discrepancy probably resides in the fact that the surface reactivity of adsorbates is often investigated using non-chemical-steady-state methods. We show here how a combination of spectroscopic and kinetic data obtained at the chemical steady-state allows quantifying the concentration of surface species and unambiguously demonstrates that the formates seen by DRIFT are not a main reaction intermediates for a range of catalyst based on Au or Pt supported on reducible oxides, despite the fact that these species exchanged as fast as the reaction product CO2 during SSITKA analysis at the higher temperature. This work demonstrates the critical importance of quantifying the IR data in order to obtain unambiguous mechanistic insight into the WGS reaction.

Operando spectrokinetic investigations of low temperature water-gas shift catalysts: SSITKA-DRIFTS-MS

241st National Meeting (2011)

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