Highly Active and Anticoke Fibrous Silica-Supported Nickel Catalyst for CO₂ Methanation

Abstract

Simplification holds significant value in both academic studies and industrial applications. Herein, a fibrous KCC-1 material is synthesized by a conventional hydrothermal method. The influence of Ni content, calcination, and activation condition on the characteristics and catalytic performances of Ni/ KCC-1 catalysts in CO 2 methanation was investigated. The physico-chemical properties of the synthesized samples were studied by X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), isotherm nitrogen adsorption, H 2 -temperature-programmed reduction (H 2 -TPR), temperature-programmed desorption (CO 2 -TPD), and Raman spectroscopy. The highly active, excellent coke-resistant, and stable Ni/KCC-1 was successfully prepared by the impregnation method under milder heat treatment (450 °C-2 h) and activation (450 °C-1 h) conditions compared to the reference catalysts. The dendritic mesoporous channels of the fibrous KCC-1 were conducive for fabrication of fine dispersion catalysts with high loading amounts of Ni. The location of Ni particles over the edges and tops of the fibrous morphology of the KCC-1 support allowed the active sites to be accessible, favoring the interaction between reactants and those active sites. Findings indicated that the obtained catalyst has a high specific surface area, high Ni dispersion, superior reducibility, very high reduction degree, high oxygen vacancy concentration, good thermal stability, and high basicity with dominant medium basic sites. The 25Ni/KCC-1 catalyst had the highest CO 2 conversion (77%) and CH 4 yield (71%) at 375 °C among the tested materials. Compared with the reference Ni/KCC-1 catalysts, the 25Ni/KCC-1 sample synthesized in this study has outstanding advantages, including superior activity and milder conditions of synthesis and activation. Furthermore, high structural stability and excellent coke resistance (0.95% coke accumulated after 100 h time on stream (TOS)) endow the Ni/KCC-1 catalyst with high stability, with stable activity throughout 100 h of TOS.