Methane tri-reforming over Ni, Ru monometallic and Ni-Ru bimetallic catalyst supported on MIL-53 metal-organic framework

Abstract

Methane tri-reforming (MTR) is a promising approach for the utilization of anthropogenic greenhouse gases such as CH₄ and CO₂ to produce syngas. In this work, the activities of monometallic (Ru, Ni) and bimetallic (Ru-Ni) catalysts supported on the alumina derived from metal-organic framework (MOF) precursors were compared for MTR. The catalysts were synthesized by impregnation technique, and their activity was investigated in a packed bed-down flow tubular reactor over a temperature range of 600–800 °C at 1 atm. The catalyst structure-activity relationship was determined with the help of extensive catalyst characterization techniques, including N₂ physisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), and CO₂ temperature-programmed desorption (CO₂-TPD). Experimental results demonstrated that the bimetallic catalyst was more active as compared to monometallic one. Among the bimetallic catalysts, 0.65RuNAl_M-53 catalyst demonstrated comparatively high CO₂ conversion (36.1 %) and an almost complete conversion of CH₄ (99.9 %) with an H₂/CO ratio of 3.2 at 800 °C. The 0.65RuNAl_M-53 catalyst showed consistent activity for a prolonged duration of > 125 h with no carbon deposition. Based on the experimental observation, a probable reaction mechanism is proposed for the MTR. The catalyst structure was intact even after 125 h of reaction, which suggested the MOF-derived Ru-Ni bimetallic catalyst developed is very promising for MTR.