Acta Phys. -Chim. Sin. ›› 2017, Vol. 33 ›› Issue (4): 745-754.doi: 10.3866/PKU.WHXB201701161

• ARTICLE • Previous Articles     Next Articles

Pyrolysis of RDX and Its Derivatives via Reactive Molecular Dynamics Simulations

Li-Juan PENG1,Qian YAO2,Jing-Bo WANG3,Ze-Rong LI2,Quan ZHU3,*(),Xiang-Yuan LI3,*()   

  1. 1 School of Aeronautics & Astronautics, Sichuan University, Chengdu 610065, P. R. China
    2 College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
    3 School of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China
  • Received:2016-10-22 Published:2017-03-23
  • Contact: Quan ZHU,Xiang-Yuan LI E-mail:qzhu@scu.edu.cn;xyli@scu.edu.cn
  • Supported by:
    The project was supported by the National Natural Science Foundation of China(91441132);Program for New Century Excellent Talents in University of Ministry of Education of China(NCET-13-0398)

Abstract:

The thermal decomposition mechanisms of cyclotrimethylene trinitramine (RDX) and its derivatives are investigated using ReaxFF reactive molecular dynamics simulation at high temperatures (2000, 2500, and 3000 K). It is shown that the first pyrolysis step of RDX and its derivatives is the N―NO2 homolytic cleavage to produce NO2; however, the subsequent reaction mechanism is completely different due to the different sixmembered rings and side chain groups. In these four model systems, NO2 and NO molecules are common intermediates in the thermal decomposition process, which eventually transform to N2 in the following reactions. The most stable products are N2, H2O, and CO2 in the thermal process, among which N2 has the maximum molecular number (more than 20). The numbers of cracked H2O and CO2 molecules are very different in the four model systems due to the different C/N and H/O ratios. At different temperatures, the maximum numbers of carbon atoms in the carbon clusters are all small in the unit cell simulations of the four systems. In the further super cell simulation for RDX and RDX-D2 the numbers of carbon atoms reach about 30 and 16, respectively, which are higher than those from the unit cell simulation. In both the unit and super cell simulations for RDX-D1 and RDX-D3, the carbon cluster cannot be formed and there exist only small carbon molecular fragments. Therefore, the initial molecular structure and elemental ratio have a large effect on the production of carbon clusters.

Key words: RDX and its derivatives, Thermal decomposition, ReaxFF, Carbon clusters, Molecular dynamics

MSC2000: 

  • O643