Promoter Effects on Nickel-Supported Magnesium Oxide Catalysts for the Carbon Dioxide Reforming of Methane

The nickel catalysts supported on bare MgO and its binary Mg–Al, Mg–La, and Mg–Fe metal oxides were prepared and used for carbon dioxide reforming of methane to syngas. The effects of Al, La, and Fe metal oxides on the structural properties, reducibility, and metal–support interaction of the Ni catalysts supported on MgO-based binary metal oxide were investigated. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and hydrogen temperature-programmed reduction (H₂-TPR) analyses show that the nickel nanoparticles were highly dispersed on the supports. It is found that the Al ions can be well-incorporated into the MgO lattice to form uniform Mg–Al oxides, while isolated lanthanum oxides and iron oxides were observed in the Mg–La and Mg–Fe binary systems by TEM, respectively. Ni/Mg–Al metal oxide exhibits greatly improved catalytic activity, owing to the formation of a homogeneous Mg–Al oxide matrix with small particle sizes of Ni nanoparticles compared to bare Ni/MgO. Very low conversions for both CH₄ and CO₂ were obtained on Ni/Mg–La and Ni/Mg–Fe metal oxides, even at a high temperature of 800 °C, as a result of the incomplete reduction of the nickel nanoparticles