Rare earths modified highly dispersed fibrous Ni/KCC-1 nanosphere catalysts with superb low-temperature CO2 methanation performances

Abstract

In this work, a series of rare earths (Pr, Sm, Ce, La) doped Ni/KCC-1 catalysts were prepared and used for CO2 methanation. It was found that doping the rare earths could greatly improve the low-temperature catalytic activities and promoting effect of Sm was more prominent than other doped counterparts (Pr, Ce, La). The effect of the Sm loading amount on the catalytic activity were further evaluated. The kinetic studies revealed that the rare earth doped catalysts performed lower apparent activation energies than the pristine Ni/KCC-1 catalyst. In order to reveal the behind reasons, these catalysts were comprehensively characterized via XRD, XPS, TEM, SEM-EDS, CO2-TPD, H2-TPR, etc. It was found that the presence of the rare earth dopants could evidently intensify the metal-support interaction, promote the dispersion of the metallic Ni active sites, generate abundant surface oxygen vacancies, and enhance the amount of the medium basic sites. Besides, the online TPSR and in-situ DRIFTS indicated that the addition of the rare earth oxides could affect the type of the reaction intermediates and the potential pathway of the CO2 methanation. In general, these rare earths doped catalysts were deemed to be the superb catalyst candidates for the low-temperature CO2 methanation.