In situ DRIFTS studies of high-temperature water-gas shift reaction on chromium-free iron oxide catalysts

The identification of reaction surface intermediates in the high-temperature water-gas shift reaction on iron oxide unpromoted and promoted MgO, SiO 2 and TiO 2 has been studied via diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The dosing of the gas mixture CO + H 2 O onto reduced Fe 2 O 3 /MgO as a function of reaction temperature produced formate species (1720, 1630 and 1370 cm −1 ) as a surface intermediate. On reduced Fe 2 O 3 /TiO 2 only bands characteristic of carbonate species (1630 and 1550 cm −1 ) are observed. A direct correlation between catalytic activity and acid/base properties of our catalysts is established. The Fe 2 O 3 /MgO basic catalyst is 100 times more active than the acidic catalyst Fe 2 O 3 /SiO 2 .