Developing cost-effective
nonprecious active metal-based catalysts for syngas (H
2
/CO) production via the dry reforming of methane (DRM) for industrial
applications has remained a challenge. Herein, we utilized a facile
and scalable mechanochemical method to develop Ba-promoted (1–5
wt %) zirconia and yttria–zirconia-supported Ni-based DRM catalysts.
BET surface area and porosity measurements, infrared, ultraviolet–visible,
and Raman spectroscopy, transmission electron microscopy, and temperature-programmed
cyclic (reduction–oxidation–reduction) experiments were
performed to characterize and elucidate the catalytic performance
of the synthesized materials. Among different catalysts tested, the
inferior catalytic performance of 5Ni/Zr was attributed to the unstable
monoclinic ZrO
2
support and weakly interacting NiO species
whereas the 5Ni/YZr system performed better because of the stable
cubic ZrO
2
phase and stronger metal–support interaction.
It is established that the addition of Ba to the catalysts improves
the oxygen-endowing capacity and stabilization of the cubic ZrO
2
and BaZrO
3
phases. Among the Ba-promoted catalysts,
owing to the optimal active metal particle size and excess ionic CO
3
2–
species, the 5Ni4Ba/YZr catalyst demonstrated
a high, stable H
2
yield (i.e., 79% with a 0.94 H
2
/CO ratio) for up to 7 h of time on stream. The 5Ni4Ba/YZr catalyst
had the highest H
2
formation rate, 1.14 mol g
–1
h
–1
and lowest apparent activation energy, 20.07
kJ/mol, among all zirconia-supported Ni catalyst systems.
H2 production through dry reforming of methane (DRM) is a hot topic amidst growing environmental and atom-economy concerns. Loading Ni-based reducible mixed oxide systems onto a thermally stable support is a reliable approach for obtaining catalysts of good dispersion and high stability. Herein, NiO was dispersed over MOx-modified-γ-Al2O3 (M = Ti, Mo, Si, or W; x = 2 or 3) through incipient wetness impregnation followed by calcination. The obtained catalyst systems were characterized by infrared, ultraviolet–visible, and X-ray photoelectron spectroscopies, and H2 temperature-programmed reduction. The mentioned synthetic procedure afforded the proper nucleation of different NiO-containing mixed oxides and/or interacting-NiO species. With different modifiers, the interaction of NiO with the γ-Al2O3 support was found to change, the Ni2+ environment was reformed exclusively, and the tendency of NiO species to undergo reduction was modified greatly. Catalyst systems 5Ni3MAl (M = Si, W) comprised a variety of species, whereby NiO interacted with the modifier and the support (e.g., NiSiO3, NiAl2O4, and NiWO3). These two catalyst systems displayed equal efficiency, >70% H2 yield at 800 °C, and were thermally stable for up to 420 min on stream. 5Ni3SiAl catalyst regained nearly all its activity during regeneration for up to two cycles.
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