Steam reforming of phenol over Ni-based catalysts – A comparative study

The influence of the support in the steam reforming of phenol at 700 °C has been examined over Ni/K-La-ZrO2 and Ni/Ce-ZrO2. Both catalysts exhibited high activity and good stability in terms of phenol conversion. However, Ni/K-La-ZrO2 showed a pronounced change in product distribution with TOS, which was related to deactivation for the water–gas shift. The high activity observed for the water- gas shift over the unsupported nickel and the difference in the location of coke between the two nickel catalysts are suggested to be the key reasons for the difference in catalyst stability. The red-ox properties of Ce-ZrO2 are proposed to result in more oxygenated species (O and OH) than the non-red-ox K-La-ZrO2. These oxygenated species, which are suggested to undergo back-spillover from the support to the nickel surface, could be responsible for keeping the nickel surface clean by gasifying the carbonaceous species accumulated on nickel.

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► The nickel catalysts studied are very active for the reforming of biomass-derived tars.
► Ni/CeO2-ZrO2 exhibited better catalyst stability than Ni/K2O-La2O3-ZrO2.
► The coke location on the catalyst is key to explain the different catalyst stability.
► The red-ox properties of CeO2-ZrO2 explain the difference in coke location.