Layered-double-hydroxide-based Ni catalyst for CO2 capture and methanation

Abstract

Ni-based catalysts prepared using layered double hydroxides (LDH) as precursors containing Mg and Ca are examined as dual-function materials for CO2 capture and methanation. X-ray diffraction, thermogravimetric analysis, H2 temperature-programmed reduction, N2 adsorption, and scanning transmission electron microscopy analyses revealed that the LDH-derived Ni catalysts form porous structures of composite oxides (MgO-NiO) containing 5-nm-sized micropores and highly dispersed 5–10-nm-sized Ni-metal nanoparticles. The methanation performance is investigated under isothermal cyclic operation with an O2-containing gas (10%-CO2/5%-O2/bal.-He) and 20%-H2/bal.-He at 320 °C; the results indicate that the LDH-derived Ni catalysts containing Ca, Mg, and Al exhibit high methanation activities. Mg contributes to the stabilization of the porous structure and enhances the Ni-metal dispersion, while Ca provides effective CO2 adsorption and storage sites.