NDA@SZTAKI

A Combined High-Temperature Experimental and Theoretical Kinetic Study of Dimethyl Carbonate with OH Radicals

Fethi, Khaled

Giri, Binod Raj

Szőri, Milán

Mai, Tam V.-T.

Huynh, Lam K.

2017

QD02 Physical chemistry / fizikai kémia

The reaction kinetics of dimethyl carbonate (DMC) and OH radicals was investigated behind reflected shock waves over the temperature range of 872-1295 K and pressures near 1.5 atm. The reaction progress was monitored by detecting OH radicals at 306.69 nm using a UV laser absorption technique. The rate coefficients for the reaction of DMC with OH radicals were extracted using a detailed kinetic model developed by Glaude et al. (Proc. Combust. Inst. 2005, 30 (1), 1111-1118). The experimental rate coefficients can be expressed in an Arrhenius form as: kexpt'l = 5.151013 exp(-2710.2/T) cm3 mol-1 s-1. To explore the detailed chemistry of DMC + OH reaction system, theoretical kinetic analyses were performed using high-level ab initio and master equation/Rice-Ramsperger-Kassel-Marcus (ME/RRKM) calculations. The geometry optimization and frequency calculations were carried out at the second-order Moller-Plesset (MP2) perturbation level of theory using the Dunning's augmented correlation consistent-polarized valence double-[small zeta] basis set (aug-cc-pVDZ). The energy was extrapolated to the complete basis set using the single point calculations performed at the CCSD(T)/cc-pVXZ (where X = D, T) level of theory. For comparison purposes, additional ab intio calculations were also carried out using the composite methods such as CBS-QB3, CBS-APNO, G3 and G4. Our calculations revealed that the H-abstraction reaction of DMC by OH radicals proceeds via an addition elimination mechanism in an overall exothermic process, eventually forming dimethyl carbonate radicals and H2O. The theoretical rate coefficiens were found to be in excellent agreement with those determined experimentally. The rate coefficients for DMC + OH reaction were combined with the literature rate coefficients of four straight chain methyl esters + OH reactions to extract the site-specific rates of H-abstraction from methyl esters by OH radicals.

angol

Article

PeerReviewed

text

http://real.mtak.hu/64439/1/Milan_046.pdf

Fethi, Khaled and Giri, Binod Raj and Szőri, Milán and Mai, Tam V.-T. and Huynh, Lam K. (2017) A Combined High-Temperature Experimental and Theoretical Kinetic Study of Dimethyl Carbonate with OH Radicals. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 19. pp. 7147-7157. ISSN 1463-9076

http://real.mtak.hu/64439/

MTMT:3184747; doi:10.1039/C6CP07318B