To investigate the oxidation of n-heptane (C7H16) under CO2/O2 atmosphere, an oxidation model (COO model) is developed using quantum chemistry and Synchrotron Vacuum Ultraviolet Photoionization Mass Spectrometry (SVUV-PIMS) technology. Electrostatic potential (ESP) and Fukui-function analyses identify reaction sites for CO2 with OH, H, CH3, and CH2 radicals and reveal reaction pathways. Oxidation experiment of C7H16 under CO2/O2 atmosphere is conducted using a jet-stirred reactor (JSR) developed with SVUV-PIMS, and the oxidation products at an equivalence ratio of 2/3, temperature range of 700–1000 K, and 1 atm are quantitatively analyzed. The results show that the COO model is applicable for the oxidation of C7H16 under CO2/O2 atmosphere, with a maximum error of 8.9 % in the oxidation of C7H16. A total of 29 oxidation products are identified, with C2H4 having the highest peak molar fraction of 1.7 × 10−2. The Negative Temperature Coefficient (NTC) region for C7H16 oxidation under CO2/O2 atmosphere is delayed by 125 K compared to O2, with the maximum reaction rate occurring at 750 K. CO2 primarily inhibits the formation of OH and other radicals before 800 K and also reacts minimally with radicals such as OH, H, CH3, and CH2, thereby delaying the NTC temperature region of C7H16. In the reaction pathways CO2+H→CO + OH and CO2+OH→CO + HO2, the highest intermediate energies are 1.75 kcal/mol higher and 73.17 kcal/mol lower than the reactants, respectively. In the pathways CO2+CH3→CO + H2O + CH and CO2+CH2→CH2O + CO, the highest intermediate energies are 147.65 kcal/mol higher and 64.13 kcal/mol lower than the reactants.
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