CO2 methanation over rare earth doped Ni based mesoporous catalysts with intensified low-temperature activity

摘要

Ni based catalysts are usually used for catalyzing the CO2 methanation to produce synthetic natural gas due to their low cost, though their catalytic activities cannot be comparable with the noble metal counterparts. In order to address this challenge, a series of rare earth (La, Ce, Sm, and Pr) doped Ni based mesoporous materials had been facilely fabricated by the one-pot evaporation induced self-assembly (EISA) strategy and directly employed as the catalysts for CO2 methanation. These mesoporous catalysts had been systematically characterized by means of X-ray diffraction, N-2 physisorption, transmission electron microscope, X-ray photoelectron spectroscopy, H-2 temperature programmed reduction, CO2 temperature programmed desorption, and so on. It was found that the Ni species were highly dispersed among the mesoporous framework and the strong metal framework interaction had been formed. Thus, the thermal sintering of the metallic Ni nanoparticles could be effectively suppressed under CO2 methanation conditions, promising these mesoporous catalysts with 50 h excellent catalytic stabilities without evident deactivation. Besides, the rare earth dopants could greatly increase the surface basicity of the catalysts and intensify the chemisorption the CO2. Further, the rare earth elements were also functioned as the electron modifiers, which was also helpful in activating the CO2 molecule. The apparent activation energies of CO2 could be obviously decreased by rare earth dopants. As a result, their low-temperature catalytic activity had been greatly intensified over these rare earth elements promoted catalysts. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.