Kinetics of OH Radical Reactions with Methane in the Temperature Range 295−660 K and with Dimethyl Ether and Methyl-tert-butyl Ether in the Temperature Range 295−618 K

Abstract

The pulse laser photolysis/laser induced fluorescence (PLP-LIF) technique has been used to measure the rate constants of the reactions of OH radicals with dimethyl ether and methyl-tert-butyl ether. OH radicals were produced by photolysis of H 2 O 2 at λ ) 266 nm. The photolysis cell was heated by a small electric furnaces in order to obtain information on the temperature dependency of the rate constants in the domain of 295-660 K. A preliminary study of the reaction of OH with methane was carried out to control the experimental setup. The Arrhenius expression obtained in the temperature range of 295-668 K, k OH+CH 4 ) (5.65 ( 0.49) × 10 -21 T 3.01 exp[-(959 ( 36)/T], is in very good agreement with previous determinations (bimolecular rate constant units: cm 3 molecule -1 s -1 ; error limits ( 2σ). For the reactions of OH with ethers, the Arrhenius expressions derived from our own results are k OH+DME (295-618 K) ) (3.02 ( 0.10) × 10 -20 T 2.85 exp[(618 ( 13)/T] and k OH+MTBE (297-616 K) ) (6.59 ( 0.43) × 10 -19 T 2.40 exp ([(499 ( 22)/T]. Combining these data with those from previous experimental studies allows us to derive Arrhenius expressions in larger temperature domains: k OH+DME (230-650 K) ) (4.59 ( 0.21) × 10 -19 T 2.46 exp[(476 ( 14)/T] and k OH+MTBE (230-750 K) ) (1.58 ( 0.09) × 10 -20 T 2.93 exp([(716 ( 18)/T].

Kinetics of the gas-phase reactions of OH radicals with alkanes and cycloalkanes

“…The recent studies of Bott and Cohen (1989), Vaghjiani and Ravishankara (1991), Finlayson-Pitts et al (1992), Lancar et al (1992), Dunlop and Tully (1993), Mellouki et al (1994), Gierczak et al (1997) and Bonard et al (2002) are in good agreement, as shown by the Arrhenius plot in Fig. 1.…”

“…This rate expression is plotted as the solid line in the Arrhenius plot ( Fig. 1), and provides an excellent fit to the data of Bott and Cohen (1989), Vaghjiani and Ravishankara (1991), Finlayson-Pitts et al (1992), Lancar et al (1992), Dunlop and Tully (1993), Mellouki et al (1994), Gierczak et al (1997) and Bonard et al (2002), agreeing with the 1234 K rate constant of Bott and Cohen (1989) to within 1% and with the 800 K rate constant of Dunlop and Tully (1993) and the 295-668 K rate constants of Bonard et al (2002) to within 10%. Accordingly, the rate expression of Gierczak et al (1997) The overall uncertainty in the rate constant at 298 K is estimated to be ±20%.…”

Dual-level direct dynamics studies for the reactions of CH3OCH3 and CF3OCH3 with the OH radical

“…Several experimental studies of the rate coefficients of reaction ͑R1͒ have been carried out below 650 K by Mellouki et al ͑230-372 K͒, 12 Nelson et al ͑298 K͒, 13 Wallington et al ͑295 K͒, 14 Wallington et al ͑240-440 K͒, 15 Tully and Droege ͑295-442 K͒, 16 Perry et al ͑299-427 K͒, 17 Arif et al ͑295-650͒, 18 and Bonard et al ͑295-618 K͒. 19 Most of these results are in good mutual agreement except for the values taken from Ref. 17, which were about 1.5 times larger than the other experimental values in the temperature range considered.…”

Multiplicative algorithm for discriminating between Arrhenius and non-Arrhenius behaviour

“…In our examples, the initial best guesses come from real experimental works [30][31][32][33] and the optimum designs obtained are robust against deviations of the initial estimates of parameters. It seems convenient to perform a thorough analysis of the behaviour of the T-optimal designs when the hypothesis or conditions assumed for their construction differ from the actual ones.…”

“…Rate coefficient for the reaction of the hydroxyl radical with methane over the temperature range of 295-668 K[31], Rate coefficient for the reaction of the hydroxyl radical with methyl ethyl ketone over the temperature range of 233Rate coefficient for the reaction of the hydroxyl radical with diethoxymethane over the temperature range of 293-617 K[33],…”