Experimental and numerical studies of ethanol decomposition reactions

Abstract

Ethanol pyrolysis experiments at 1.7 - 3.0 atm and 1045 - 1080 K were performed in the presence of radical trappers using a variable pressure flow reactor. Stable species time histories were determined using continuous sampling, on-line Fourier transform infrared spectrometry, and off-line gas chromatography. The rate constant k 1 of the molecular decomposition reaction, C 2H 5OH → C 2H 4 + H 2O (R1), was determined experimentally. The obtained result agrees very well with extrapolation of the recent shock-tube data of Herzler et al. 1 The multichannel unimolecular decomposition of ethanol was also investigated theoretically on the basis of RRKM/master equation calculations. The effects of the hindered rotations in C 2H 5OH and quantum tunneling on the molecular decomposition reaction were taken into account. The reaction R1 was found to be strongly dependent on temperature and the dominant channel over the range of temperatures 300-2500 K at 1 atm. The calculated k 1 is in excellent agreement with the recent theoretical work of Tsang 2 as well as with the experimental measurements of Herzler et al. 1 and the present data. The influence of tunneling on the shape of the falloff is discussed. In addition, the RRKM/master equation results were fit to modified Arrhenius expressions to facilitate chemical kinetic modeling applications of the results.