| Summary: | The dry reforming of methane (DRM) was studied for seven hours at 800 °C and 42 L/(g·h) gas hourly space velocity over Ni-based catalysts, promoted with various amounts of gadolinium oxide (x = 0.0, 1.0, 2.0, 3.0, 4.0, and 5.0 wt.%) and supported on mesoporous yttrium-zirconium oxide (YZr). The best catalyst was found to have 4.0 wt.% of gadolinium, which resulted in ∼80% and ∼86% conversions of CH<sub>4</sub> and CO<sub>2</sub>, respectively, and a mole ratio of ∼0.90 H<sub>2</sub>/CO. The addition of Gd<sub>2</sub>O<sub>3</sub> shifted the diffraction peaks of the support to higher angles, indicating the incorporation of the promoter into the unit cell of the YZr support. The Gd<sub>2</sub>O<sub>3</sub> promoter improved the catalyst basicity and the interaction of NiO with support, which were reflected in the coke resistance (6.0 wt.% carbon deposit on 5Ni+4Gd/YZr; 19.0 wt.% carbon deposit on 5Ni/YZr) and the stability of our catalysts. The Gd<sub>2</sub>O<sub>3</sub> is believed to react with carbon dioxide to form oxycarbonate species and helps to gasify the surface of the catalysts. In addition, the Gd<sub>2</sub>O<sub>3</sub> enhanced the activation of CH<sub>4</sub> and its conversion on the metallic nickel sites.
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