▎ 摘　　要

Multilayer graphene-encapsulated iron nanoparticles in carbon frames were prepared through catalytic graphitization of kraft lignin as carbon sources using irons as the catalyst at the temperature of 1000 degrees C under argon atmosphere. The effects of different iron loadings on the formation of multilayer graphene-encapsulated iron nanoparticles were investigated using thermogravimetric analysis and temperature-programmed decomposition. The evolution of gaseous products (H-2, CH4, CO, and CO2) was measured using an online mass spectroscopy during the catalytic thermal decomposition of kraft lignin. Solid products were measured and characterized by elemental analysis, nitrogen adsorption, X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. Thermogravimetric analysis curves indicated that peak temperatures of lignin decomposition and carbonization shifted to lower temperatures with an increase of iron/lignin mass ratio. Experimental results showed that the lignin graphitization degree and conversion level to graphene materials increased significantly with the increase of iron/lignin mass ratio.