Dry Reforming of Methane over Ni-Fe-Al Catalysts Prepared by Solution Combustion Synthesis

Dry reforming of methane (DRM) is a promising method to utilize two greenhouse gases, such as CH₄ and CO₂, to produce synthesis gas. In the current work, both monometallic Ni and bimetallic Ni-Fe catalysts with different Fe/Ni molar ratios, synthesized by solution combustion synthesis (SCS) in DRM, were investigated using a feed ratio of CH₄/CO₂/Ar of 1:1:1 at 600-900 °C. The catalysts were characterized by several physicochemical techniques such as X-ray diffraction (XRD), scanning electron microscopy energy-dispersive X-ray (SEM-EDX) spectroscopy, transmission electron microscopy (TEM), CHNS, N₂ physisorption, H₂-TPR, O₂-TPO, NH₃-TPD, and thermogravimetric analysis (TGA). One of the highest hydrogen yields of 81% was obtained at 93% conversion of CH₄ and 94% conversion of CO₂ for the bimetallic 15Ni-5Fe-30Al catalyst, which contained, according to XRD, NiAl₂O₄ spinel and metallic Ni phases. The spinel phase was decomposed during the reaction, while the Ni₃Fe alloy was formed. Catalysts with a higher Fe/Ni ratio exhibited lower conversion and contained an inactive FeAl₂O₄ spinel. Rather stable yields of CO and H₂ were obtained in an experiment with 20 h time-on-stream.