Promotion or additive activity? The role of gold on zirconia supported iron oxide in high temperature water-gas shift

• Sulfur can probe the role of gold in Au/Fe2O3/ZrO2 catalyst in WGS at industrial conditions.
• The active site(s) on gold nano–particles onAu/ZrO2 are poisoned by sulfur.
• The promotion by gold of the Fe2O3 is still present after presulfidation.

Sulfur addition is used to probe the role of gold in Au/Fe2O3/ZrO2 catalyst in the water-gas shift (WGS) at high temperature (623–773 K) and pressure (21 bar). Sulfur poisoning unravels the WGS activity contribution by gold nano-particles and gold promotion of iron oxide in Au/Fe2O3/ZrO2. The active site(s) on gold nano-particles are poisoned by sulfur, which is reflected in a suppressed WGS activity of presulfided Au/ZrO2. The same holds for the WGS activity contribution of gold nano-particles in Au/Fe2O3/ZrO2, but the promotion by gold of the Fe2O3 is still present after presulfidation. The WGS performance of Fe2O3/ZrO2 and Au/ZrO2 catalysts with and without sulfur pretreatment are also compared with that of Au/Fe2O3/ZrO2.

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