Binary and ternary transition metal phosphides for dry reforming of methane†
In this work, both binary and ternary transition metal phosphides (MoP, WP, Ni2P, Fe2P, CoP, NiMoP and CoMoP) were used as potential catalysts for dry reforming of methane (DRM). Moreover, Ni2P, Fe2P, CoP, NiMoP and CoMoP were tested in DRM for the first time. A comparison of various phosphide catalysts identified Mo-based phosphides (MoP, NiMoP and CoMoP) as having much higher DRM activity than phosphides of W, Ni, Fe and Co. It was worth mentioning that CoMoP can show a similar catalytic activity and stability to the Pt/γ-Al2O3 catalyst. The XRD, Raman and SEM results indicated that the resistance to coking, bulk oxidation and sintering of Mo-based phosphides was higher than that of phosphides of metals (W, Ni, Co and Fe). Furthermore, CoMoP exhibited the highest resistance to coking, oxidation and sintering among these phosphide catalysts. It was proposed that both the quantity and location of active sites for CH4 and CO2 dissociation over phosphides were crucial to maintain the oxidation–reduction cycle in DRM.