Molecular Dynamics of Combustion Reactions in Supercritical Carbon Dioxide. 6. Computational Kinetics of Reactions between Hydrogen Atom and Oxygen Molecule H + O₂ ⇌ HO + O and H + O₂ ⇌ HO₂

Abstract

Reactions of the hydrogen atom and the oxygen molecule are among the most important ones in the hydrogen and hydrocarbon oxidation mechanisms, including combustion in a supercritical CO 2 (sCO 2 ) environment, known as oxy-combustion or the Allam cycle. Development of these energy technologies requires understanding of chemical kinetics of H + O 2 ⇌ HO + O and H + O 2 ⇌ HO 2 in high pressures and concentrations of CO 2 . Here, we combine quantum treatment of the reaction system by the transition state theory with classical molecular dynamics simulation and the multistate empirical valence bonding method to treat environmental effects. Potential of mean force in the sCO 2 solvent at various temperatures 1000−2000 K and pressures 100−400 atm was obtained. The reaction rate for H + O 2 ⇌ HO + O was found to be pressure-independent and described by the extended Arrhenius equation 4.23 × 10 −7 T −0.73 exp(−21 855.2 cal/mol/RT) cm 3 /molecule/ s, while the reaction rate H + O 2 ⇌ HO 2 is pressure-dependent and can be expressed as 5.22 × 10 −2 T −2.86 exp(−7247.4 cal/mol/RT) cm 3 /molecule/s at 300 atm.

Biodiesel fuel. Part III. Quantum chemical research and simulation of the process

“…Было показано, что все реакции дегидратации ускоряются, когда молекулы воды принимают участие в реакции. Авторы [9][10][11] квантово-химически исследовали поверхности потенциальной энергии отдельных элементарных актов реакций горения в присутствии сверхкритического углекислого газа. В работе [11] были изучены три радикальных реакции: H 2 CO + HO 2 → HCO + H 2 O 2 , 2HO 2 → H 2 O 2 + O 2 и CO + OH → CO 2 + H. Результаты показывают, что среда CO 2 может оказывать каталитическое воздействие в реакциях горения, которые должны быть включены в кинетические механизмы горения в сверхкритическом CO 2 .…”