Nickel nanoparticles supported on nitrogen–doped carbon nanotubes are a highly active, selective and stable CO2 methanation catalyst

• Published in: Journal of energy chemistry 2021-03, Vol.54, p.323-331
• Main Authors: Gödde, Julian, Merko, Mariia, Xia, Wei, Muhler, Martin
• Format: Article
• Language: English
• Subjects: Carbon nanotubes; CO2 methanation; Nickel nanoparticles; Nitrogen doping
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2020.06.007

Ni/NCNT is highly active and selective in CO2 methanation with an optimum loading of 30 wt%−40wt% Ni and similar catalytic properties for 10wt% to 50wt% Ni. N-functionalization of the CNTs is essential for high stability. [Display omitted] •Ni nanoparticles supported on N-functionalized CNTs were used for CO2 methanation.•51% conversion and 96% selectivity were achieved using 30wt% Ni loading at 340 °C.•CO2 methanation over the Ni/NCNT catalysts is structure-insensitive.•High stability under CO2 methanation conditions was demonstrated for 100 h. CO2 methanation using nickel-based catalysts has attracted large interest as a promising power-to-gas route. Ni nanoparticles supported on nitrogen-doped CNTs with Ni loadings in the range from 10 wt% to 50 wt% were synthesized by impregnation, calcination and reduction and characterized by elemental analysis, X-ray powder diffraction, H2 temperature-programmed reduction, CO pulse chemisorption and transmission electron microscopy. The Ni/NCNT catalysts were highly active in CO2 methanation at atmospheric pressure, reaching over 50% CO2 conversion and over 95% CH4 selectivity at 340 °C and a GHSV of 50,000 mL g−1h−1 under kinetically controlled conditions. The small Ni particle sizes below 10 nm despite the high Ni loading is ascribed to the efficient anchoring on the N-doped CNTs. The optimum loading of 30 wt%–40 wt% Ni was found to result in the highest Ni surface area, the highest degree of conversion and the highest selectivity to methane. A constant TOF of 0.3 s−1 was obtained indicating similar catalytic properties of the Ni nanoparticles in the range from 10 wt% to 50wt% Ni loading. Long-term experiments showed that the Ni/NCNT catalyst with 30 wt% Ni was highly stable for 100 h time on stream.