Insights into the thermal stability and conversion of carbon-based materials by using ReaxFF reactive force field: Recent advances and future directions

Molecular simulations based on reactive force-fields (ReaxFF) have been applied as a powerful tool for exploring the dynamics evolution of complex carbonaceous materials. A comprehensive review of the thermal degradation reactions of renewable and nonrenewable carbon precursors at different conditions is presented, aiming at gaining molecular insights on mitigating heavy carbonaceous deposition in undesirable scenarios using molecular simulation tools, while providing some perspectives and future directions on the subject. The review is divided in three main interconnected areas: (i) overview on the implementation of ReaxFF simulations, structural extraction techniques and microstructural characteristic properties of carbon-based materials, followed by (ii) proposed biomass, bio-oil, and bio-fuel reaction mechanisms from which, the tendency of coke and char formation is tackled. Finally, (iii) understanding nonrenewable coal, soot, coal char, and petroleum derivatives (petcoke) carbonaceous materials reactivity under high-temperature thermochemical reactions. A critical discussion is presented on the effects of temperature and functional groups on the structural evolution of large-scale atomistic structures, initial ring cleavage reactions, along with the generated products yields and characteristics. Suggested improvements in the ReaxFF implementation methodology and parametrization approach are made, followed by future directions on incorporating catalytic surfaces for tackling bio-oil upgrading in regards to coke formation and deposition.