Study on Atmospheric Photo-oxidation of Methyl Hydroperoxide Initiated by Cl-atom
SHI Fei,CHEN Zhong-ming
The State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences, Peking University, Beijing 100871, China
Abstract:Organic peroxides play an important role in chemistry of the atmosphere and in controlling urban air quality; however, accurate knowledge about their atmospheric reactions is lacking. In this paper, the experimental simulation was employed to study the atmospheric photo-oxidation of methyl hydroperoxide (CH3OOH, MHP), a key organic peroxide in the atmosphere. At the temperature of (292±2)K and pressure of 9.3×104 Pa (20% O2+80% N2), the MHP photo-oxidation was initiated by Cl-atom and the process of reaction was in-situ observed by long path Fourier transform infrared (Long Path FTIR) spectrometry. From FTIR spectra, the main products observed were formaldehyde (HCHO), formic acid (HCOOH), carbon monoxide (CO) and carbon dioxide (CO2), and minor methanol (CH3OH) was found as well. Within the reaction period of 60 min, yields were determined: 24% for HCOOH and 6% for CO; 50% for HCHO at its maximum concentration although its yield was varying with the reaction time. Finally, reaction mechanisms were discussed, which implied that MHP is a reservoir of odd-hydrogen radicals (HOx) and plays an important role in atmospheric photo-reactions.
[1] Qi B, Zhang Y H, Chen Z M et al. Chemosphere , 1999, 38: 1213. [2] Logan J A, Prather M J, Wofsy S C et al. J. Geophys. Res., 1981, 86: 7210. [3] Levy H. Planet. Space Sci., 1972, 20: 919. [4] Crutzen P J. Annu. Rev. Earth Planet Sci., 1979, 7: 443. [5] Jackson A V, Hewitt C N. Critical Reviews in Environ. Sci. and Technol., 1999, 29: 175. [6] Niki H, Maker P D, Sabage C M et al. J. Phys. Chem., 1983, 87: 2190. [7] Vaghjiani G L, Ravishankara A R. J. Phys. Chem., 1989, 93: 1948. [8] CHEN Zhong-ming, TANG Xiao-yan, WANG Mei-rong et al(陈忠明, 唐孝炎, 王美蓉等). Acta Scientiae Circumstantiae (环境科学学报), 1996, 16: 258. [9] Akimoto H, Bandow H, Sakamaki F et al. Environ. Sci. Technol., 1980, 14: 172. [10] Hanst P L. Fourier Transform Infrared Spectroscopy: Applications to Chemical Systems, Vol. 2. (Ferraro J R,Basile L J, eds), New York:Academic Press, 1979. 95. [11] Prather M J. Scientific Assessment of Stratospheric Ozone: 1989, WMO Report No. 20, Vol. 2, Geneva: World Meteorological Organization, 1990. 149. [12] Atkinson R, Baulch D L, Cox R A et al. J. Phys. Chem. Ref. Data, 1997, 26: 521.