Ni-Fe nanocatalysts supported on CeO2have
been prepared
for the catalysis of methane steam reforming (MSR) aiming for coke-resistant
noble metal-free catalysts. The catalysts have been synthesized by
traditional incipient wetness impregnation as well as dry ball milling,
a green and more sustainable preparation method. The impact of the
synthesis method on the catalytic performance and the catalysts’
nanostructure has been investigated. The influence of Fe addition
has been addressed as well. The reducibility and the electronic and
crystalline structure of Ni and Ni-Fe mono- and bimetallic catalysts
have been characterized by temperature programmed reduction (H2-TPR), in situ synchrotron X-ray diffraction (SXRD), X-ray
photoelectron spectroscopy (XPS), and Raman spectroscopy. Their catalytic
activity was tested between 700 and 950 °C at 108 L gcat–1h–1and with the reactant
flow varying between 54 and 415 L gcat–1h–1at 700 °C. Hydrogen production rates
of 67 mol gmet–1h–1have been achieved. The performance of the ball-milled Fe0.1Ni0.9/CeO2catalyst was similar to that of
Ni/CeO2at high temperatures, but Raman spectroscopy revealed
a higher amount of highly defective carbon on the surface of Ni-Fe
nanocatalysts. The reorganization of the surface under MSR of the
ball-milled NiFe/CeO2has been monitored by in situ near-ambient
pressure XPS experiments, where a strong reorganization of the Ni-Fe
nanoparticles with segregation of Fe toward the surface has been observed.
Despite the catalytic activity being lower in the low-temperature
regime, Fe addition for the milled nanocatalyst increased the coke
resistance and could be an efficient alternative to industrial Ni/Al2O3catalysts.