Theoretical Research on the Combustion Mechanism and Kinetics for Aluminum and Carbon Dioxide

Abstract

AbstractThe reaction mechanism and kinetics of ground state aluminum (Al) atom and carbon dioxide (CO2) molecule were studied by quantum chemical calculations. The transition states and reaction paths were investigated at the B3LYP/6‐311+G(d,p) (Becke type three‐parameter Lee‐Yang‐Parr functional model) basis set. The energy of each stagnation point was calculated at the high‐precision CBS‐QB3 (limiting complete basis set) level of theory. The reaction of CO2 with Al is a complex process. There are four basic reaction processes and two main reaction paths (Reaction pathway 1: Al+CO2→IM1→TS1→IM2→TS2→AlO (2Π)+CO and Reaction pathway 2: Al+CO2→IM3→TS3→AlCO2linear→TS4→AlO (2Σ)+CO). The temperature‐ and pressure‐dependent rate constants of the reaction of Al and CO2 was estimated by CBS‐QB3//B3LYP/6‐311+G(d,p) level at 300∼3000 K, which is combined with Transition State Theory (TST), Variational Transition State Theory (VTST), and Rice‐Ramsperger‐Kassel‐Marcus (RRKM) theory. The total rate constant of Reaction pathway 1 (ktotal,1) is much higher than that of Reaction pathway 2 (ktotal,2), indicating that the reaction of Al with CO2 is easier to occur through Reaction pathway 1. Compared with ktotal,2, ktotal,1 shows a strong pressure dependence at high temperature, but it is almost independent with the pressure at low temperature.