Comparative molecular dynamics study of the temperature-dependent performance of NiFe and graphite catalysts in methane decomposition for hydrogen production

A comparative study of methane decomposition processes using NiFe catalyst, representing the transition metal group known for its ability to reduce activation energy, and graphite catalyst, representing carbon materials with diverse morphologies and abundant natural availability, was conducted using molecular dynamics simulations. The simulation findings suggest that a 100 K temperature increment results in only a very slight increase in the diffusion rate. The NiFe catalyst outperforms graphite in methane decomposition by providing both faster decomposition kinetics and significantly enhanced diffusion of carbon and hydrogen atoms. Nevertheless, the accumulation of these atomic species on the catalyst surface leads to the blockage of active sites and a decrease in catalytic activity. The activation energy required for the methane gas decomposition process with the NiFe catalyst is 0.20 eV, while with the graphite catalyst, it is 0.72 eV. In the methane gas decomposition process with NiFe catalyst, no CH, CH₂, and CH₃ bonds were found, indicating that methane decomposes directly and completely into hydrogen and carbon atoms separately. Meanwhile, with the graphite catalyst, the decomposition of CH₄ into simpler compounds (CH, CH₂, and CH₃) was observed.