Abstract
Surface structure of bimetallic catalysts plays a vital role in converting liquid hydrocarbon fuels to on-site H2 for fuel cell application via steam reforming process. Herein, Pt-outer (Pt-Ni/Al2O3), Pt-outer & inner (NiPt/Al2O3) and Pt-inner (Ni-Pt/Al2O3) catalysts prepared through sequential impregnation and co-impregnation method were employed in n-dodecane steam reforming. Performance results showed that the activity was as followed: Ni-Pt/Al2O3 > NiPt/Al2O3 > Pt-Ni/Al2O3. Characterization results from XRD, H2-TPR, XPS, STEM-EDX, in situ CO-DRIFT and EXAFS suggest that Ni-Pt/Al2O3 catalyst was more preferable to form Nix+ species and NiPt alloy compared with Pt-Ni/Al2O3 and NiPt/Al2O3 catalysts. C2H6-TPSR and H2O-TPSR experimental indicated that Ni-Pt/Al2O3 catalyst and Nix+ species mostly contributed to CC, CH bond and H2O activation. The superior activity of Ni-Pt/Al2O3 bimetallic catalyst in n-dodecane steam reforming linked with the synergistic effect between Ni-enriched surface, Nix+ species and NiPt alloy which facilitated CHx group formation, H2O activation and CHx group oxidation.
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•Varied surface structures of NiPt catalysts prepared by tailing Pt locations were tested in n-dodecane steam reforming.•High steam reforming activity was achieved over Ni-Pt/Al2O3 catalyst (Pt-inner catalyst).•Pt atoms located inner were more preferable to form Nix+ species and NiPt alloy.•Pt located inner structure enhanced CC, CH bond and H2O activation.•Less carbon was formed over Ni-Pt/Al2O3, mainly as filamentous coke/disordered carbon.