tailieunhanh - Study on the pathways of the reaction of ketenyl radicals and nitrogen dioxide (HCCO + NO2)

Using the G3B3 method, we constructed the portions of potential energy surface containing low-energy pathways of HCCO + NO2 reaction. These show that only two separate reaction pathways are possible leading to HCNO + CO2 and HCO + NO + CO. | Journal of Chemistry Vol. 45 2 P. 223 - 227 2007 study on the pathways of the reaction of KETENyL radicals and nitrogen dioxide HCCO NO2 Received 23 May 2006 LAM NGQC THIEM 1 MAI THU HIEN2 NGUyEN THANH LAM3 SHAUN A. CARl3 NGUyEN MINH THQ3 1Vietnam National University 2Institute of Industrial Chemistry Department of Chemistry University of Leuven Belgium SUMMARy Using the G3B3 method we constructed the portions of potential energy surface containing low-energy pathways of HCCO NO2 reaction. These show that only two separate reaction pathways are possible leading to HCNO CO2 and HCO NO CO. I - INTRODUCTION During hydrocarbon combustion under fuelrich conditions the chemical flux through the ketenyl radical is therefore expected to be one of the largest of all the small C-containing radicals 1 . The HCCO radical takes part significantly in the removal of NO in NOx-reburning strategies 2 - 5 in which nitric oxide formed in stationary combination systems is removed by small radicals such as HCCO CH CH2 CH3 and C2H that are generated under fuel-rich conditions in a second combustion stage after the primary combustion zone. In this context we set out to determine the possible products of the reaction HCCO NO2. Portions of the potential energy surface containing the reaction channel leading to the formation of possible products have thus been constructed making use of high level quantum chemical methods. II - CQMPUTATIQNAl METHODS We attempt to identify the probable product channels making use of quantum chemical calculations. All calculations were performed using the Gaussian 03 suite of programs 7 . Optimizations of the stationary-point geometries reactants products and transition structures were conducted using density functional theory DFT with the popular hybrid functional B3LYP in conjunction with 6-311 G d p basic set. The harmonic vibrational frequencies and the zero-point energies ZPE were also computed at B3LYP 6-311 G d p . The zeropoint energies were scaled .