Issue 3, 2022

Effect of a single water molecule on ˙CH2OH + 3O2 reaction under atmospheric and combustion conditions

Abstract

The hydroxymethyl (˙CH2OH) radical is an important intermediate species in both atmosphere and combustion reaction systems. The rate coefficients for ˙CH2OH + 3O2 and (˙CH2OH + 3O2 (+H2O)) reactions were calculated using the Rice–Ramsperger–Kassel–Marcus (RRKM)/master equation (ME) simulation and canonical variational transition state theory (CVT) between the temperature range of 200 to 1500 K based on the potential energy surface constructed using CCSD(T)//ωB97XD/6-311++G(3df,3pd). The results show that ˙CH2OH + 3O2 leads to the formation of CH2O and HO2 at temperatures below 800 K, and goes back to reactants at high temperature (>1000 K). When a water molecule is added to the reaction, the formation of CH2O and HO2 is favored at all temperatures. The calculated rate coefficient for the ˙CH2OH + 3O2 (2.8 × 10−11 cm3 molecule−1 s−1 at 298 K) is in good agreement with the previous experimental values (∼1 × 10−11 cm3 molecule−1 s−1 at 298 K). The rate coefficients for the water-assisted reaction (2.4 × 10−16 cm3 molecule−1 s−1 at 1000 K) is at least 3–4 orders of magnitude smaller than the water-free reaction (6.2 × 10−12 cm3 molecule−1 s−1 at 1000 K). This result is consistent with the similar types of reaction system. Our calculations also predict that the effect of a single water molecule favors the formation of CH2O in the combustion condition. However, the water-free reaction favors the formation of CH2O in the atmospheric condition. The current study helps to understand how a single water molecule changes the reaction mechanism and chemical kinetic behaviour under atmospheric and combustion conditions.

Graphical abstract: Effect of a single water molecule on ˙CH2OH + 3O2 reaction under atmospheric and combustion conditions

Supplementary files

Article information

Article type
Paper
Submitted
25 Aug 2021
Accepted
24 Nov 2021
First published
25 Nov 2021

Phys. Chem. Chem. Phys., 2022,24, 1510-1519

Effect of a single water molecule on ˙CH2OH + 3O2 reaction under atmospheric and combustion conditions

M. R. Dash and M. Akbar Ali, Phys. Chem. Chem. Phys., 2022, 24, 1510 DOI: 10.1039/D1CP03911C

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