Ba2+ doping into Ni/Al2O3 nanofibers promotes CO2 methanation via alkaline modulation

Ni-based catalysts are promising catalysts for CO2 methanation due to low lost. However, the activity and selectivity of Ni-based catalysts in CO2 methanation at low temperatures still need to be improved. Here, Ni4Al2BamOx (m = 0-0.5) nanofibers were prepared. Doping Ba2+ would increase alkaline sites and facilitate generating oxygen vacancies. Especially, Ni4Al2Ba0.2Ox exhibited the high specific surface area with 127.1 m(2) g(-1), being potential for exposing more active sites. Indeed, compared with undoped Ni4Al2Ox catalysts (CO2 conv. = 45 %, CH4 select. = 92 % at 300 degrees C), Ba2+ doping significantly improved activity (CO2 conv. = 74 %, CH4 select. = 99% at 300 degrees C) and stability within 200 h for Ni(4)Al(2)Ba(0.2)Ox. Both EPR and O-1S XPS confirmed that Ni(4)Al(2)Ba(0.2)Ox can form more oxygen vacancies and CO2-TPD confirmed that Ni(4)Al(2)Ba(0.2)Ox had stronger CO2 adsorption capacity compared to Ni4Al2Ox. In-situ infrared spectroscopy and DFT calculations both indicated that Ba2+ doping can promote generating surface hydroxyl groups and formate pathways.