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Evaluating the Atmospheric Loss of $H_{2}$ by $NO_{3}$ Radicals: A Theoretical Study
| Content Provider | MDPI |
|---|---|
| Author | Romanias, Manolis N. Nguyen, Thanh Lam |
| Copyright Year | 2022 |
| Description | Molecular hydrogen $(H_{2}$) is now considered among the most prominent substitute for fossil fuels. The environmental impacts of a hydrogen economy have received more attention in the last years, but still, the knowledge is relatively poor. In this work, the reaction of $H_{2}$ with $NO_{3}$ radical (the dominant night-time detergent of the atmosphere) is studied for the first time using high-level composite G3B3 and modification of high accuracy extrapolated ab initio thermochemistry (mHEAT) methods in combination with statistical kinetics analysis using non-separable semi-classical transition state theory (SCTST). The reaction mechanism is characterized, and it is found to proceed as a direct H-abstraction process to yield $HNO_{3}$ plus H atom. The reaction enthalpy is calculated to be 12.8 kJ $mol^{−1}$, in excellent agreement with a benchmark active thermochemical tables (ATcT) value of 12.2 ± 0.3 kJ $mol^{−1}$. The energy barrier of the title reaction was calculated to be 74.6 and 76.7 kJ $mol^{−1}$ with G3B3 and mHEAT methods, respectively. The kinetics calculations with the non-separable SCTST theory give a modified-Arrhenius expression of k(T) = $10^{−15}$ × $T^{0.7}$ × exp(−6120/T) $(cm^{3}$ $s^{−1}$) for T = 200–400 K and provide an upper limit value of $10^{−22}$ $cm^{3}$ $s^{−1}$ at 298 K for the reaction rate coefficient. Therefore, as compared to the main consumption pathway of $H_{2}$ by OH radicals, the title reaction plays an unimportant role in $H_{2}$ loss in the Earth’s atmosphere and is a negligible source of $HNO_{3}$. |
| Starting Page | 1313 |
| e-ISSN | 20734433 |
| DOI | 10.3390/atmos13081313 |
| Journal | Atmosphere |
| Issue Number | 8 |
| Volume Number | 13 |
| Language | English |
| Publisher | MDPI |
| Publisher Date | 2022-08-18 |
| Access Restriction | Open |
| Subject Keyword | Atmosphere Atomic, Molecular and Chemical Physics Kinetics Cfour Sctst H2 Fuel No3 |
| Content Type | Text |
| Resource Type | Article |
