Thermal cracking of light hydrocarbons and their mixtures

Abstract

The kinetics and product distributions of the thermal cracking of binary and ternary mixtures of ethane, propane, nand i-butane were determined in a pilot plant under conditions of residence time, temperature, total pressure, and dilution as close as possible to those prevailing in industrial operation. The kinetics and yields observed with ternary mixtures were compared with those obtained with binary mixtures and with pure components. The experimental selectivities were compared with those which would be obtained from separate cracking and subsequent addition of the product streams. The deviations between the two can be predicted by means of the so-called global kinetics selectivities, which are based upon the selectivities obtained from the pure components cracking and upon the global rates of cracking of the feed components in the mixture.

Thermal cracking of substituted aromatic hydrocarbons. I. Kinetic study of the thermal cracking of i-propylbenzene

“…The yields of some major products were plotted against conver- The product distribution of cumene cracking can be compared with that of i-butane, which has an analogous structure, except that methyl is replaced by phenyl. In the products of i-butane cracking, propylene and i-butene are major products, while the ethylene yields are rather low [3]. This is in agreement with the effluent composition of cumene cracking, provided that propylene corresponds to styrene and i-butene to alpha-methylstyrene.…”

“…Indeed, the rate constant of reaction (39), 3.45 x lo6 l/s at 1000 K, is close to that of reaction (40), 4.54 X lo6 l/s. Though the rate constant of (42) is smaller, the concentration of the alpha-cumyl radical is high, since the hydrogen abstraction reactions forming this radical proceed more rapidly than those forming beta-cumyl.…”

“…For the cracking of i-butane and n-butane, Froment et al [3] obtained activation energies and frequency factors varying slightly with the partial pressures of the butanes. The first order global kinetics, with E = 206.9 kJ/mol and log A = 10.94, yield a rate constant of i-butane disappearance k = 0.68 l/s at 700 "C. At the same temperature, cumene disappears with k = 5.09, using E = 207.9 kJ/mol and log A = 11.867, as obtained from the present experiments.…”

Thermal cracking of JP-10: Kinetics and product distribution

“…Greek Letters e expansion factor t space time, s n stoichiometric coefficient, moles of total product /mol of JP-10 cracked effects are expected to be negligible [7]. A mercury manometer with one leg connected to system and the other leg open to the atmosphere was used to measure the pressure difference between the system and the surroundings.…”

Experimental study of hydrocarbon structure effects on the composition of its pyrolysis products

“…Studies of homological hydrocarbons were performed mainly for linear and non-linear alkanes [29,[35][36][37][38], but they were not aimed at developing the structure-selectivity relationships. Their goals were mainly the research of radical reactions mechanism including the confirmation of Rice-Kosiakoff theory [3,16,26,29,34,35,39], the estimation of reaction order and reaction rates of pyrolysis reactions [3,7,13,16,24,26,29,34,[39][40][41][42], or the effect of temperature on the selectivity of products formation [3,13,16,24,26,29,34,35,38,41].…”