Experimental determination of the temperature dependence of the absolute rate coefficients of the HCCO + NO2 and HCCO + H2 reactions
Abstract
The absolute rate coefficients of the gas-phase reactions HCCO + NO2 and HCCO + H2 were experimentally determined for the first time over extended temperature ranges: 293 K to 769 K and 438 K to 761 K, respectively. HCCO radicals were generated by pulsed-laser photolysis of CH2CO at 193 nm. Their subsequent decay, under pseudo-first-order conditions, was monitored in real-time using a laser-photofragment/laser-induced fluorescence technique. The rate coefficient of HCCO + NO2 exhibits a negative temperature dependence similar to that of the HCCO + NO reaction, but the Arrhenius A-factor is 1.4 times larger; k(T)(HCCO+NO2) = (2.3 ± 0.4) × 10−11 exp (340 ± 40) K/T) cm3 s−1. It is argued that, if the major product channels yield N, NH or NCO, the HCCO + NO2 reaction should be a significant removal route of NOx in stationary combustion systems under