Moderate Fe incorporation suppresses methane formation in ethanol steam reforming over La–Ce oxide-supported Ni catalysts

Controlling methane selectivity at complete ethanol conversion remains a demanding challenge in ethanol steam reforming (ESR) over Ni catalysts, because CH 4 formation directly limits the attainable H 2 yield. Here, a series of Ni catalysts supported on La–Ce oxides with systematically varied Fe contents (Ni/La 1 Ce 2 Fe x O 1.5 x +5.5 , x = 0–1.0) and comparable Ni particle sizes (6–8 nm) was synthesized to investigate how support-incorporated Fe affects methane formation. Among the compositions examined, a moderate Fe content ( x = 0.4) gave the highest H 2 yield of 90.8% and the lowest CH 4 selectivity of 4.8%, compared with 80.4% and 12.4%, respectively, for the Fe-free catalyst. The observed selectivity trend was not associated with substantial changes in Ni particle size, whereas no clear evidence for extensive Ni–Fe alloying was found. Meanwhile, moderate Fe incorporation promoted the emergence of a LaFeO 3 -related phase and increased the defect-related character of the La–Ce oxide support. Ethanol–water temperature-programmed surface reaction and in situ infrared spectroscopy revealed H 2 O participation at lower temperatures and altered evolution of oxygenated surface intermediates upon moderate Fe incorporation, consistent with an important support-mediated contribution to the lower CH 4 selectivity. Excessive Fe incorporation, however, increased coke formation and led to catalyst deactivation. These findings highlight oxide-support defect engineering as a means of regulating H 2 O-assisted surface chemistry and C 1 product selectivity, providing broader guidance for the design of Ni-based catalysts for efficient H 2 production from alcohol reforming.