Effect of Zn addition on the performance of Ni/Al2O3 catalyst for steam reforming of ethanol

• Two ZnO/Al2O3 supported Ni catalysts with different Zn/Al ratio were tested for the steam reforming of ethanol.
• For Ni/ZnAl2O4 catalyst (Zn/Al = 0.5), only metallic Ni particles were found after reduction. In this case, carbon filaments were formed during SR of ethanol, leading to catalyst deactivation.
• NiZn alloy with different compositions are formed after reduction of Ni/ZnO-Al2O3 (Zn/Al = 2.0). This catalyst exhibited high stability and resistance to carbon buildup.
• NiZn alloy formation is shown to play a key role on the resistance to metal particle oxidation and the inhibition to carbon deposition.

A detailed investigation of the effect of Zn on the performance of supported Ni-based catalysts for steam reforming of ethanol is presented in this paper. A Ni/Al2O3 and two ZnO/Al2O3 supported Ni catalysts with different Zn/Al ratio were prepared. For the Ni/Al2O3 and Ni/ZnAl2O4 (Zn/Al = 0.5) catalysts, only metallic Ni particles were identified after reduction. Under ethanol steam reforming conditions, carbon filaments were formed during the reaction, which led to deactivation of the catalyst. It was shown that Zn present in excess (Ni/ZnO-Al2O3) may form an alloy with compositions ranging from Zn-rich tetragonal NiZn and Ni-rich cubic Ni4Zn. The formation of NiZn alloy with different compositions plays a key role in catalyst performance, improving resistance to coke formation and its stability.

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