Mechanistic Behavior of Basicity of Bimetallic Ni/ZrO2 Mixed Oxides for Stable Oxythermal Reforming of CH4 with CO2

Abstract

The mixed oxides of Ni/ZrO2, Ni-Ca/ZrO2, Ni-Ba/ZrO2, and Ni-Ba-Ca/ZrO2 were prepared using the co-precipitation method at a pH of precisely 8.3. The catalytic mixed oxides of Ni/ZrO2, Ni-Ca/ZrO2, Ni-Ba/ZrO2, and Ni-Ba-Ca/ZrO2 were characterized using x-ray diffraction XRD, Brunauer Emmett Teller (BET), scanning electron microscopy (SEM), and metal dispersion for the screening of phase purity, surface area, and morphology. The mixed oxides are subjected to CO2-TPD to quantify the basicity of every composition. The mixed oxide catalysts of Ni/ZrO2, Ni-Ca/ZrO2, Ni-Ba/ZrO2, and Ni-Ba-Ca/ZrO2 were screened for oxythermal reforming of CH4 with CO2 in a fixed bed tubular reactor at 800 °C. Among all catalysts, the Ba- and Ca- loaded Ni-Ba-Ca/ZrO2 showed high conversion by the decomposition of methane and CO2 disproportionation throughout the time on stream of 29 h. The high activity with stability led to less coke formation over Ni-Ba-Ca/ZrO2 over the surface. The stable syngas production with an active catalyst bed contributed to the improved bimetallic synergy. The high surface basicity of Ni-Ba-Ca/ZrO2 may keep actively gasifying the formed soot and allow for further stable reforming reactions.