The formation of alkanes in the pyrolysis of n-hexadecane: effect of an inert gas on the decomposition of alkyl radicals

Abstract

The rate of formation of alkanes in the pyrolysis of n-hexadecane is shown to be drastically reduced in the presence of an inert gas.The experimental results are in good quantitative agreement with the predictions of a theoretical model, which assumes that the decomposition of alkyl radicals is not monomolecular, because the Maxwell–Boltzmann activation process would be perturbed by a bimolecular reaction having a lower activation energy.

Influence of pressure (100 Pa–100 Mpa) on the pyrolysis of an alkane at moderate temperature (603 K–723 K): Experiments and kinetic modeling

“…Rice, Herzfeld and Kossiakoff [58][59][60] were the first to explain the thermal cracking of hydrocarbons by a chain reaction mechanism propagated by free radicals at low temperature. Their theory was then confirmed by different teams in low pressure conditions [1,43,44] and some others in high pressure conditions [2,35,37,38,41,43,45,46]. The pyrolysis mechanism constructed in this study was lumped by applying the procedure already described [61,62].…”

“…The experiments performed at low pressure (about 100 Pa) showed that alkanes and olefins are generated in almost equal quantity [1,43,44]. On the other side very few olefins and notable amounts of alkanes are produced in experiments carried out at very high pressure [2,39,43,[45][46][47][48][49]. Some authors also studied the influence of pressure on the n-alkane conversion.…”

Liquid-phase thermal decomposition of hexadecane: reaction mechanisms

“…The first-order rate constants are 0.27 X 10~3,1.5 X '3, and 7.5 X 10"3 h'1 for 330, 350, and 370 °C, respectively. Figure 2 gives the rate data for both liquidphase and gas-phase thermal decomposition of n-hexadecane (Fabuss et al, 1962;Voge and Good, 1949;Tilicheev and Zimina, 1956;Doue and Guiochon, 1968; Panchenkov and Baranov, 1958;Groenendyk et al, 1970), The activation energy is about 57 kcal/mol over a range of rate constants of 7 orders of magnitude. Excellent agreement between liquid-and gas-phase data was seen.…”

High pressure pyrolysis of n-heptane

“…These authors also modified the free radical mechanism of Rice and Kossiakoff to account for the products formed under high pressure gas-phase pyrolysis [25]. Pyrolysis of several hydrocarbons such as n-hexadecane [26][27][28][29][30][31][32], decalin [28], C 21 -C 27 paraffins [30], dodecane [33], C 9 -C 22 alkanes [34], and pristane, phytane and squalane [35] have been investigated at high pressures. Song et al [36] investigated the condensed-phase pyrolysis of n-tetradecane at elevated pressures.…”