Journal of Analytical and Applied Pyrolysis 90 (2011) 27–32 Contents lists available at ScienceDirect Journal of Analytical and Applied Pyrolysis journal homepage: www.elsevier.com/locate/jaap Experimental study on the thermal decomposition of 2H-heptafluoropropane Yonghua Hu a,b,∗ , Yingbo Xu a , Tianfang Wang b,c , Chenghui Wang a , Shufen Li b,∗∗ a Technology Center, China Tobacco Anhui Industrial Corporation, Hefei, Anhui 230088, PR China b Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, PR China c Department of Chemistry, The University of Adelaide, Adelaide, South Australia 5005, Australia article info Article history: Received 9 October 2009 Accepted 18 October 2010 Available online 23 October 2010 Keywords: 2H-Heptafluoropropane Thermal decomposition FTIR Acid–base titrate Fluoride ion selective electrode abstract This is an extension study of the thermal decomposition of 2H-heptafluoropropane (HFP), mainly aiming at investigating the relationship between pyrolysis characteristics and reaction time, and evaluating the production of hydrogen fluoride (HF). The results indicate that reaction temperatures have obvious effects on the decomposition of HFP. Pure HFP does not decompose at 400, 500 and 600 ◦ C. It starts to decompose at about 640 ◦ C, markedly breaks down at 700 ◦ C and exhibits intense decompositions at 800 ◦ C; meanwhile, coke formation was observed on the inner surface of the reactor. Moreover, it can also be found that the reaction time has obvious effect on the thermal decomposition processes of HFP. From 700 to 800 ◦ C the decomposition becomes increasingly drastic, and the concentration of HF produced highly depends on reaction temperature and time. This hints that when the total amount of HFP remains constant during practical application, the promotion of the spraying current capacity and the reduction of spraying time can reduce the production amount of HF, which can further lessen the harm to the personnel and the environment. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Halon fire extinguishing agents, such as Halon-1301 (CF 3 Br) and Halon-1211(CF 2 ClBr), were widely used in the past due to their high flame inhibition efficiency. However, halons are potent ozone-depleting substances (ODSs) and synthetic green house gases (GHGs). The wide use of them has caused severe damage to the ozone layer and contributed significantly to the global warming [1–3]. In order to hasten the recovery of the ozone layer, inter- national legislations, the Montreal Protocol and its Copenhagen Amendment, mandated the phase out of production and use of ODSs by all countries according to a specified timetable, which, in turn, has prompted a worldwide search for proper alternative fire suppressants that possess zero potential for ozone depletion yet are efficient in extinguishing a flame. 2H-Heptafluoropropane, commonly referred to as HFP or HFC- 227ea, having the chemical formula of CF 3 CHFCF 3 , is believed to be a kind of ideal substitute, and used as fire-extinguishing agent more and more widely [4–6]. More than that, it can be used in a number of industrial applications, such as refrigerating medium, medical propellants, manufacturing of polymeric foams, and so ∗ Corresponding author at: Technology Center, China Tobacco Anhui Industrial Corporation, 9 Tian Da Road, Gaoxin Zone, Hefei, Anhui 230088, PR China. Tel.: +86 551 5738650; fax: +86 551 5392201. ∗∗ Corresponding author. Tel.: +86 551 3601137; fax: +86 551 3631760. E-mail addresses: huyh@mail.ustc.edu.cn (Y. Hu), lsf@ustc.edu.cn (S. Li). forth. Under normal pressure, the property of pure HFP reveals itself to be a colorless and tasteless gas. The research has suggested that its global warming potential (GWP) is 0.3–0.5 and atmosphere lifetime (ALT) is 31–42 years, which are much better than those of halons. It is generally believed that the fire suppression mechanism of HFP is similar to that of halons, and can be separated to physi- cal and chemical modes [4,7,8]. The physical contribution to flame suppression mainly stems from the heat-absorbing ability of the agent, which results in the flame temperature and the radical chain reaction rates decreasing in the flame. As to chemical suppression mechanism, some kinds of fluorine-containing free radicals would be formed during the thermal decomposition of HFP at the first stage; these radicals can react with the active radicals, e.g., O, H and OH, which play very important roles in the whole combus- tion process. This interrupts or terminates some key chain reactions that can be crucial for flame propagation. At the same time, some fluorocarbon compounds are generated, which have been proved to exhibit excellent fire suppression effects. Therefore, in order to understand its fire extinguishment mechanisms and properties, it is of significance to investigate the thermal degradation of HFP. During the past decade, a series of experimental investigations have been carried out to study the thermal decomposition of HFP. Ritter [9] studied the pyrolysis of HFP mixture (2% HFP in nitrogen) at atmospheric pressure in the temperature ranging from 1023 to 1173 K, and 0–2 s reaction time in a quartz tubular flow reactor. It was found that HFP did not decompose appreciably at tempera- ture below 1023 K and requires temperatures in excess of 1173 K for complete conversion, and major gas phase products included 0165-2370/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jaap.2010.10.006