Catalyst properties influence the reaction rates, coking rate, and product selectivity (H2/CO) in dry reforming of methane (DRM). Nickel exsolved from spinels can achieve improved coking resistance and high reaction rates. In this study, we investigated for the first time the DRM performance of NiCr2O4 synthesized at different temperatures (500, 650, 800°C) and benchmarked against Ni/MgAl2O4. The catalysts were tested at 700°C, 180,000 ml/gcat.hr, 1:1 CH4/CO2 feed ratio, atmospheric pressure, and 20 h time on stream. Higher calcination temperatures favored NiCr2O4 phase formation and led to larger spinel crystallites. The catalyst calcined at 500°C (NiCr2O4-500) had H2-TPR peaks at lower temperatures, suggesting ease of reduction, and had a Ni region H2 consumption of 0.44 mmol/gcat. After H2 reduction at 700oC, exsolved Ni from the spinel phase with well-anchored interaction was observed on Cr2O3 support. NiCr2O4-500 had higher CH4 (394 ± 44 mmol/gcat.h) and CO2 (337 ± 44 mmol/gcat.h) reaction rates than Ni/MgAl2O4. The reducibility and amphoteric properties of Cr2O3 contributed to CH4 activation, hence r'CH4 > r'CO2, which is atypical in DRM. Cr2O3 also modulated the reaction pathways to limit reverse water gas shift (RWGS) reaction thereby enhancing H2 selectivity (H2/CO = 0.8) compared to 0.6 for Ni/MgAl2O4. If r'CH4 > r'CO2, coking rate is expected to be high as less oxidant is available in the reaction environment. However, NiCr2O4-500 still exhibited the least normalized coking rate (32.5 µgcarbon/mmolCH4), an order of magnitude lower than for Ni/MgAl2O4 (229.5 µgcarbon/mmolCH4). NiCr2O4 catalysts had a higher graphitic to amorphous coke mass ratio than Ni/MgAl2O4. The results demonstrate that NiCr2O4 catalysts can simultaneously achieve a high H2/CO ratio and low coking rate in DRM. This study provides valuable insights into the role of material properties in optimizing catalyst performance in DRM, paving the way for the design of efficient catalysts for the industry.
