Structural evolution of robust Ni3Fe1 alloy on Al2O3 in dry reforming of methane: Effect of iron-surplus strategy from Ni1Fe1 to Ni3Fe1

Bimetallic Ni−Fe alloy catalyst offers boosting effect for dry reforming of methane (DRM) by strong interaction between Ni and Fe. However, the facile segregation of iron species from the alloy particles remains an open challenge. Herein, in pursuit of a stable Ni−Fe alloy, Ni1Fe1/Al2O3 and Ni3Fe1/Al2O3 catalysts were developed by an evaporation-induced self-assembly method. Ni1Fe1/Al2O3 exhibited superior stability to Ni3Fe1/Al2O3 at 600 °C for 50 h. The structural evolution of Ni−Fe alloys existed on Ni1Fe1/Al2O3 and Ni3Fe1/Al2O3 in DRM, leading to the generation of Ni3Fe1/Al2O3 and Ni/Al2O3, respectively, where the equimolar alloy provided sufficient FeOx in the dealloying process. Compared to Ni3Fe1/Al2O3, Ni1Fe1/Al2O3 possessed smaller amounts of coke deposition with lower graphitization, which is beneficial to realloying of the segregated FeOx for Ni−Fe alloy. Furthermore, the two catalysts presented distinct pathways for coke deposition, where CO and CH4 dissociation concurrently occurred on Ni3Fe1/Al2O3, while only CH4 dissociation appeared on Ni1Fe1/Al2O3.