Enhancement of methanation of bio-syngas over CeO_2-modified Ni/Al_2O_3 catalysts

摘要

CeO_2 modified Ni/Al_2O_3 catalysts were developed for synthetic natural gas (SNG) from bio-syngas methanation. Physiochemical properties of the CeO_2 modified Ni/Al_2O_3 catalysts were characterized by N_2 physical adsorption (BET), scanning electron microscopy (SEM), temperature-programmed reduction of hydrogen (H_2-TPR), X-ray diffraction (XRD) and thermo gravimetric analyzer (TGA). The bio-syngas methanation tests showed that adding 60 wt% of CeO_2 in the Ni/CeO_2-Al_2O_3 catalyst presented excellent bio-syngas methanation performances (91.6% carbon oxides conversion with 92% CH_4 selectivity) at low temperature (350 ℃). The characterization results indicated that adding of CeO_2 into Ni/Al_2O_3 strengthened the NiO-CeO_2 interaction via the weakening of the interaction between Ni species and Al_2O_3, facilitating the separation of NiO from NiAl_2O_4. The optimal CeO_2 content of 60 wt.% was obtained to disperse well Ni species and increase active metallic Ni sites, promoting the catalytic performances for bio-syngas methanation to SNG.