Initiation reactions in acetylene pyrolysis
Journal Article
·
· Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
- Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- Sandia National Lab. (SNL-CA), Livermore, CA (United States); Grinnell College, Grinnell, IA (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States)
In gas-phase combustion systems the interest in acetylene stems largely from its role in molecular weight growth processes. The consensus is that above 1500 K acetylene pyrolysis starts mainly with the homolytic fission of the C–H bond creating an ethynyl radical and an H atom. However, below ~1500 K this reaction is too slow to initiate the chain reaction. It has been hypothesized that instead of dissociation, self-reaction initiates this process. Nevertheless, rigorous theoretical or direct experimental evidence is lacking, to an extent that even the molecular mechanism is debated in the literature. In this work we use rigorous ab initio transition-state theory master equation methods to calculate pressure- and temperature-dependent rate coefficients for the association of two acetylene molecules and related reactions. We establish the role of vinylidene, the high-energy isomer of acetylene in this process, compare our results with available experimental data, and assess the competition between the first-order and second-order initiation steps. As a result, we also show the effect of the rapid isomerization among the participating wells and highlight the need for time-scale analysis when phenomenological rate coefficients are compared to observed time scales in certain experiments.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States); Sandia National Laboratories (SNL-CA), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Workforce Development for Teachers and Scientists (WDTS) (SC-27)
- Grant/Contract Number:
- AC02-06CH11357; AC04-94AL85000
- OSTI ID:
- 1367347
- Alternate ID(s):
- OSTI ID: 1373597
OSTI ID: 1458100
- Report Number(s):
- SAND--2017-5238J; 653388
- Journal Information:
- Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Journal Name: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory Journal Issue: 22 Vol. 121; ISSN 1089-5639
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Pressure-Dependent Rate Constant Predictions Utilizing the Inverse Laplace Transform: A Victim of Deficient Input Data
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