Effect of oxygen addition on the water–gas shift reaction over Pt/CeO2 catalysts in microchannels – Results from catalyst testing and reactor performance in the kW scale

• Catalysts were tested for water–gas shift with and without air addition.
• Especially the activity at low reaction temperature (260 °C) could be improved.
• Ceria supported samples lost activity after exposure to a surplus of air.
• A water–gas shift reactor of kW scale showed higher conversion with air in the feed.

Wash-coated Pt/CeO2, Pt/CeO2/ZrO2 and Pt/Cu/CeO2 and Pt/CeO2/Al2O3 based formulations were tested in sandwich type microreactors for water–gas shift (WGS) activity. At low reaction temperature of 260 °C, low conversion of carbon monoxide was initially observed which increased considerably upon the addition of air, a behaviour which was observed even after multiple cycles of start-up, operation with and without air and shut-down. At a higher reaction temperature of 400 °C air addition did not further improve the performance of the catalysts, which converted the carbon monoxide already close to equilibrium. One of the catalysts was incorporated into a larger reactor of kW scale and tested for its performance under conditions of WGS and oxygen enhanced WGS. The carbon monoxide conversion was increased by the air addition also on the larger reactor.