An ab initio chemical kinetic study on the reactions of H, OH, and Cl with HOClO3

✍ Scribed by R. S. Zhu; M. C. Lin

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 278 KB
• Volume: 42
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20459

✦ Synopsis

Abstract

The mechanisms for reactions of H, HO, and Cl with HOClO~3~, important elementary processes in the early stages of the ammonium perchlorate (AP) combustion reaction, have been investigated at the CCSD(T)/6‐311+G(3df,2p)//PW91PW91/6‐311+G(3df) level of theory. The rate constants for the low‐energy channels have been calculated by statistical theory. For the reaction of H and HOClO~3~, the main channels are the production of H~2~ + ClO~4~ (k~1a~) and HO + HOClO~2~ (k~1b~); k~1a~ and k~1b~ can be represented as 1.07 × 10^−17^ T^1.97^ exp(−7484/T) and 6.08 × 10^−17^T^1.96^ exp(−7729/T) cm^3^ molecule^−1^ s^−1^, respectively. For the HO + HOClO~3~ reaction, the main pathway is the H~2~O + ClO~4~ (k~2a~) production process, with the predicted rate constant k~2a~ = 1.24 × 10 ^−8^ T^−2.99^ exp(1664/T) for 300–500 K and k~2a~ = 1.27×10^−19^ T^2.12^ exp(−1474/T) for 500–3000 K. For the Cl + HOClO~3~ reaction, the formation of HOCl + ClO~3~ (k~3a~) and HCl + ClO~4~ (k~3b~) is dominant, with k~3a~ = 1.33×10^−12^ T^0.67^ exp(−9658/T) and k~3b~ = 1.75×10^16^ T^1.63^ exp(−11156/T) cm^3^ molecules^−1^ in the range of 300–3000 K. In addition, the heats of formation of ClO~3~ and HOClO~3~ have been predicted based on several isodesmic and/or isogyric reactions with Δ~f~H^o^~0~ (ClO~3~) = 47.0 ± 1.0 and Δ~f~H^o^~0~ (HOClO~3~) = 5.5 ± 1.5 kcal/mol, respectively. These data may be used for kinetic simulation of the AP decomposition and combustion reaction. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 253–261, 2010