Electric field modulation effect and mechanism on n-alkanes fuel pyrolysis: A ReaxFF MD and DFT study

Abstract

To promote the fuel utilization efficiency in the aviation and space transport, the electric field was selected as an efficiency method to modify the fuel pyrolysis rate. This work investigated the surrogate fuel component n-alkane (n-pentane, n-heptane and n-decane) pyrolysis process under the electric field. The three n-alkanes pyrolysis rate and reaction pathway were analyzed. And the reaction mechanism under the electric field was discussed by the bond cracking potential energy (PES), system thermal motion and energy. The molecular dynamics results showed the n-alkanes pyrolysis was modulated by the electric field strength, which promotion in weak electric field and inhibition in strong field. The species transformation net was complicated and selective while the conversion flux was reduced by the strong field. The field improved the molecule polarization and deformation to result in the edged carbon bond and H bond dissociation with lower energy barriers. Analyzing the molecular motion and system energy, the intermolecular distance was elongated, and interaction energy was reduced, which caused to the decrease of collision frequency under the field. The contribution of electric field to the single molecule decomposition and inhibition molecules motion worked together on the global n-alkane pyrolysis. This work supplied a theory support to the promoting fuel utilization using the electric energy.