Samarium oxide (Sm2O3) is a versatile surface for CO2 and H2 interaction and conversion. Samarium oxide-supported Ni, samarium oxide-supported Co-Ni, and samarium oxide-supported Ru-Ni catalysts were tested for CO2 methanation and were characterized by X-ray diffraction, nitrogen physisorption, infrared spectroscopy, H2-temperature programmed reduction, and X-ray photoelectron spectroscopy. Limited H2 dissociation and widely available surface carbonate and formate species over 20 wt.% Ni, dispersed over Sm2O3, resulted in ~98% CH4 selectivity. The low selectivity for CO could be due to the reforming reaction between CH4 (methanation product) and CO2. Co-impregnation of cobalt with nickel over Sm2O3 had high surface adsorbed oxygen and higher CO selectivity. On the other hand, co-impregnation of ruthenium and nickel over Sm2O3 led to more than one catalytic active site, carbonate species, lack of formate species, and 94% CH4 selectivity. It indicated the following route of CH4 synthesis over Ru-Ni/Sm2O3; carbonate → unstable formate → CO → CH4.
Finding a robust catalytic system for hydrogen production via dry reforming of methane (DRM) remains a challenge. Herein, MNi 0.9 Zr 1−x Y x O 3 (M = Ce, La, and La 0.6 Ce 0.4 ; x = 0.00, 0.05, 0.07, and 0.09) catalyst was prepared by the sol-gel method, tested for DRM and characterized by surface area and porosity, X-ray diffraction, H 2 -temperature programmed reduction, thermogravimetry, and transmission electron microscopy. In La 0.6 Ce 0.4 NiO 3 catalyst, the substitution of Ni by 0.1% Zr results in a constant high catalytic activity (83% hydrogen yield at 800°C) due to the presence of reducible "NiO-species interacted strongly with the support" (stable metallic Ni over reduced catalyst) and redox input by ceria phase for laying instant lattice oxygen during lag-off period of CO 2 . Substitution of Ni by Zr and Y in the CeNiO 3 catalyst system nurtures Ni 3 Y (providing highly stable metallic Ni for CH 4 decomposition) and cerium yttrium oxide phases (providing strong redox input). CeNi 0.9 Zr 0.01 Y 0.09 O 3 shows 85% H 2 yield at 800°C.
A better understanding of the reaction mechanism and kinetics of dry reforming of methane (DRM) remains challenging, necessitating additional research to develop robust catalytic systems with high catalytic performance, low cost, and high stability. Herein, we prepared a zirconia-alumina-supported Ni-Fe catalyst and used it for DRM. Different partial pressures and temperatures are used to test the dry reforming of methane reaction as a detailed kinetic study. The optimal reaction conditions for DRM catalysis are 800°C reaction temperature, 43.42 kPa CO2 partial pressure, and 57.9 kPa CH4 partial pressure. At these optimal reaction conditions, the catalyst shows a 0.436 kPa2 equilibrium constant, a 0.7725
m
o
l
C
H
4
/gCat/h rate of CH4 consumption, a 0.00651
m
o
l
C
H
4
/m2/h arial rate of CH4 consumption, a 1.6515
m
o
l
H
2
/gCat/h rate of H2 formation, a 1.4386 molCO/gCat/h rate of CO formation. This study’s findings will inspire the cost-effective production of robust catalytic systems and a better understanding of the DRM reaction’s kinetics.
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