CO 2 methanation is a promising process for producing methane as a hydrogen carrier while reducing atmospheric CO 2

levels, off ering a sustainable pathway for achieving a carbon cycle through the power-to-gas (P2G) system. In this study, a 

green catalyst for CO 2 methanation was developed using cellulose nanofi ber (CNF), a renewable material, as the support. 

Ni and Mg were dispersed on CNF and subsequently calcined at 500 °C to obtain a CNF-derived carbon-supported Ni 

and Mg catalyst (NiMg/CNF), designed to minimize carbon deposition. NiMg/CNF catalyst exhibited signifi cantly higher 

CO 2 conversion (~ 85%) and CH 4 selectivity (~ 99%) at 350 °C, compared to a bulk cellulose-supported catalyst. This 

improved performance was likely attributed to the nanofi ber structure of CNF and its abundant oxygen functional groups, 

which can facilitate metal nanodispersion. TEM analysis confi rmed that Ni and Mg were uniformly dispersed as nanoscale 

particles (< 5 nm) on the CNF support. SEM images of the NiMg/CNF revealed curved thin-fi lm sheets interconnected in 

a three-dimensional network, with large void spaces that can provide eff ective pathways for mass transport. The NiMg/

CNF catalyst maintained relatively stable activity during a 100 h continuous reaction, with CO 2 conversion stabilizing 

around ~ 85% and CH 4 selectivity remaining above 98% until the fi nal stage of the test. XRD pattern of the post-reaction 

sample closely matched that of the fresh one, indicating that Ni and Mg maintained structural stability on the CNF support.