Effect of phase transformation on the stability of Ni-Mg-Al catalyst for dry reforming of methane

A series of Ni/Mg(Al)O hydrotalcite-derived catalysts are prepared via the carbonate co-precipitation method at different calcination temperatures. The performance and stability of the catalysts are studied through carbon dioxide reforming of CH4 to synthesis gas at 800 degrees C, atmospheric pressure, and gas hourly space velocity of 8000 mL/g(cat) h. The decrease in activity of catalysts calcined at 600, 700, and 800 degrees C results from the MgO film surrounding the Ni-0 particles in the initial reaction stage. The activity is renewed and maintained when the MgO film is destroyed on reaction with Al2O3 to form the MgAl2O4 spinel-like phase. Formation of the MgAl2O4 spinel-like phase during the reaction is considered beneficial to the catalytic activity because of removal of the MgO film surrounding Ni-0. The conversion of CH4 and CO2 is stable at over 95% after reaction for 2000 h. The catalysts have small Ni-metal particles, strong metal-support interaction and excellent anti-carbon deposition.