# Reaction Pathway Analysis of Methane and Propylene Cracking: A Reactive Force Field Simulation Approach

## TL;DR

This paper uses simulations to track how methane and propylene break down into carbon-based products, revealing differences in their reaction pathways.

## Contribution

A new algorithm tracks reaction pathways in gas-phase cracking using reactive force field simulations at large scales.

## Key findings

- Methane cracking is simpler, involving C–H bond cleavage and radical chain propagation.
- Propylene cracking produces more complex reaction networks due to its unsaturated structure and multiple reactive sites.
- The algorithm provides mechanistic insights for optimizing carbon-based material design.

## Abstract

This study presents the development and validation of an elementary reaction pathway tracking algorithm based on reactive force field simulations, enabling the dynamic monitoring of cracking products at the 20,000-atom scale, the accurate identification of chain reaction pathways, and the comprehensive tracking of large carbon chain formation. The research demonstrates that the differences between methane and propylene cracking–polymerization reactions primarily stem from disparities in bond dissociation energies, radical stabilities, and molecular topologies, and the operation of molecular dynamics relies on LAMMPS 3 March 2020. The cracking pathway of methane is relatively straightforward, predominantly involving the homolytic cleavage of C–H bonds, followed by radical chain propagation leading to the formation of large carbonaceous species. In contrast, propylene, owing to its unsaturated structure and multiple reactive sites, exhibits more complex reaction networks and a wider diversity of products. Furthermore, the study elucidates the reaction pathways of intermediate species during methane and propylene cracking and investigates the effect of reaction temperature on carbon sheet development. In conclusion, the algorithm established in this work offers a detailed mechanistic insight into the gas-phase cracking of methane and propylene, providing a new theoretical basis for the optimization of gas-phase deposition processes and the rational design of carbon-based materials.