(192o) Enhancing the Oxidation of Toluene with External Electric Fields: A Reactive Molecular Dynamics Study

Enhancing
the Oxidation of Toluene with External Electric Fields: a Reactive Molecular
Dynamics Study

Shen
Tan, Tao Xia, Yao Shi, and Yi He*

College of
Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, P.
R. China

*Corresponding
author: yihezj@zju.edu.cn

Tuning
chemical reactions with external
electric field (Efield) has long been a
desirable goal for researchers. Molecular simulation methods based on reactive
force fields (ReaxFF) is recently developed for the study of chemical reactions in large
systems at a micro-scale. To this end, the effects of Efields on chemical reactions were studied with the
ReaxFF MD simulations by using the oxidation of toluene as a model system. We
observed that Efields may greatly enhance the oxidation rate of toluene. The initial reaction time of toluene is also
reduced remarkably in Efields. A stronger Efield leads to a faster oxidation
rate of toluene. Further studies reveal that the applying of Efields may
results in the oxidation of toluene at 2100 K which is otherwise not able to
happen when Efield is not at present. The oxidation rate of toluene at 2100 K
in Efield is comparable with the oxidation rate of toluene at 2900 K when
Efield is not applied. In addition, Efield was observed to significantly
enhance the occurrence of the initial radical generation for different pathways
of toluene oxidation but it does not seem to favor any of the pathways.
Finally, Efields do not seem to enhance
the polarization of toluene during its transition state, which suggests that a
polarizable charge equilibration
method (QEq) method might be needed to take the effects of Efields into
consideration.

Figure. 1 Evolution of the toluene and oxygen molecules at density ¦Ñ = 0.15, 0.35 g/cm³, Efield = 0, 0.2 V/Å (ReaxFF NVT-MD simulation, T = 2500 K, toluene/oxygen= 1:100).