Details

Autor(en) / Beteiligte

• Hung, Wei-Chung
• Tsai, Chieh-Ying
• Matsui, Hiroyuki
• Wang, Niann-Shiah
• Miyoshi, Akira

Titel

Experimental and Theoretical Study on the Thermal Decomposition of C3H6 (Propene)

Ist Teil von

• The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 2015-02, Vol.119 (8), p.1229-1237

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The mechanism of the thermal unimolecular decomposition of C3H6 (propene) is studied both theoretically and experimentally. The potential energy surfaces for possible reaction pathways are investigated by CBS-QB3 level of quantum chemical calculations, and RRKM/master-equation calculation is performed for the main channels. The time evolutions of H atoms are observed experimentally by using a highly sensitive detection technique (ARAS, detection limit ≈ 1011 atoms cm–3) behind reflected shock waves (0.5–1.0 ppm C3H6 diluted in Ar, 1450–1710 K at 2.0 atm). The objective of this study is to examine the main product channels by combining the experimental and theoretical investigations on the yield and the rates of H atom production. Present quantum chemical calculations identify reactions (1a–1d) as the candidates of product channels: C3H6 → aC3H5 (allyl radical) + H (1a), C3H6 → CH3 + C2H3 (vinyl radical) (1b), C3H6 → CH4 + :CCH2 (singlet vinyldene radical) (1c), and C3H6 → C3H4 (allene) + H2 (1d). The RRKM calculations reveal the branching fractions for (1a), (1b), and (1c) to be approximately 0.8, 0.2, and 0.01, respectively. Reaction (1d) and other product channels are negligible (< 0.1 %), and the pressure dependence of the branching fraction is small under the present experimental conditions. The experimental yield of H atoms (1.7–2.0) is consistent with the theoretical branching fractions considering the H-atom production from the rapid subsequent thermal decomposition of a C3H5 and C2H3. From the observed time profiles of H atoms, the rate of overall thermal decomposition of C3H6 can be evaluated as Ln(k 1/s–1) = (38.05 ± 1.18) – (48.91 ± 1.85) × 103 K/T, which is in excellent agreement with the theoretical prediction.