Deactivation of Gold-Ferrochrome Very Low Temperature Water-Gas Shift Catalysts

Gold-ferrochrome catalysts are active for water-gas shift at temperatures below 200 degrees Celsius, but they deactivate rapidly. The deactivation can be attributed primarily to two factors: sintering of the gold nanoparticles present in the catalyst, and deposition of carbon on the surface of the catalyst. High resolution transmission electron microscopy and X-ray diffraction characterization of fresh and used catalysts provide evidence for the former. The effect of reductive pretreatments using carbon-containing gases and carbon-free gases and in-situ gravimetric studies under reaction conditions provide evidence for carbon deposition. Additional characterization using BET, SEM and NEXAFS shows that the ferrochrome component of the catalyst is not altered significantly as the catalyst deactivates.