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

Abstract

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.

Dry Reforming of Methane over Rare-Earth Metal Oxide Ni–M–Al (M = Ce, La) Catalysts

“…The results from elemental analysis of the fresh and some spent catalysts (Table S2) show that nickel content in the bimetallic catalysts was ca. 17 wt % except in 15Ni–35Al, where it reached 42 wt %, as reported in the previous study . In trimetallic catalysts, the Ni amounts varied in the range of 24–26 wt %.…”

“…The XRD profile of bimetallic 15Ni–35Al was shown in the previous study . The bimetallic 15Ni–35Al exhibited only amorphous features, while the amorphous content in 15Ni–35Ce appears to be rather large (Figure a).…”

“… a The spent catalysts were used in DRM for 30 min at 850 °C with a GHSV of 3000 h –1 . b From ref , Ni particle size. c 30 min of TOS. d Temperature cycling experiment at 600–900–600 °C. e 10 h of TOS at 850 °C. f 20 h of TOS at 850 °C. …”

“…As a comparison, the Ni catalyst supported onto a commercial alumina gave initial conversion values of CH 4 and CO 2 of 50 and 60%, respectively, decreasing thereafter, while the H 2 /CO ratio remained constant for 20 h (Table S1, entry 4) . In contrast, the 15Ni–5Fe–30Al catalyst exhibited good performance during DRM in spite of its high acidity . In addition, even if the surface area of Ni–Fe–Al was the lowest among other catalysts demonstrated in Table S1, it was highly active and stable for 20 h (Table S1, entry 5).…”

“…On the other hand, especially supported nickel catalysts are prone to deactivation, which can be mitigated at least partially by fine-tuning the catalyst composition. For example, CeO 2 and La 2 O 3 have been intensively tested as promoters or supports for Ni, − ,− ,,, while other modifications involve the use of encapsulated Ni nanoparticles or mesoporous supports for Ni as well as modifications with iron . The main idea has been to suppress the sintering of Ni and coking with these methods.…”