Kinetics of carbon monoxide and hydrogen-atom production from the decomposition of cyanic acid in shock waves

The thermal reaction of HNCO at moderate temperatures

“…(1) HNCO + Ar -NH + CO + Ar obtained from these two independent studies, which agree closely, can be given by k1 = 1015.925~0.085 exp(-42,640 2 450/T) cm3/mol s for the broad temperature range, 1830 K 5 T 5 3340 K [8]. Because of the large activation energy, 85 kcal/mol, the reaction was not measurable below 1800 K within the time scale employed in shock tube studies, t 5 1 ms.…”

“…The measured product yields of CO, COz, HCN, and NH3 and the disappearance rates of HNCO could not be interpreted with an established hightemperature decomposition mechanism [7,8], but could be satisfactorily explained by the introduction of a new bimolecular reaction (2), 2HNCO -+ C02 + HNCNH. This reaction can not only explain the prompt formation of COz, but also account for the production of HCN, NH3, and CO by the subsequent reactions of HNCNH.…”

“…The mechanism employed to simulate CO, CO2, HNCO, HCN, and NH3 concentrations at different reaction-time intervals was based primarily on the one established recently for the HNCO decomposition in shock waves [7,8,15,16]. The original high temperature mechanism, however, is inadequate for the interpretation of observed CO and HNCO concentration profiles, not to mention that of C02.…”

“…Both HCN and NO2 are known to be produced in the early stage of RDX and HMX decomposition reactions There has been a considerable current interest in the kinetics and mechanism of HNCO reactions at high temperatures because of its potential as a rapid deNO, agent [5] and as a convenient source of the NH radical, which plays a n important role in the deNO, process and in the high-temperature N-containing fuel chemistry [6]. The thermal decomposition of HNCO at high temperatures (T 2 1800 K) has been investigated in detail by Mertens et al [7] and Wu and coworkers [8] in shock waves employing different diagnostic techniques. The second-order rate constant for the unimolecular decomposition reaction in Ar:…”

Combustion Chemistry of Nitrogen

“…has been studied in shock tubes by Mertens et al (1989) and Wu et al (1990) with concordant results. We suggest adoption of the Wu et al expression, which is valid for argon bath gas over the temperature range from 1830 to 3340 K. The measured activation energy suggests that the barrier for reverse reaction is small, which implies that there is no significant energy barrier on the surface for spin reversal.…”