Pyrolysis of a mixture of n-alkanes (chiefly C12-C18) atCA. 1053 K: Kinetic study

The thermal decomposition of a mixtures of n-alkanes, chiefly C₁₂-C₁₈ (commercial name Solpar) in the presence of steam (steam cracking) was studied in a plug flow reactor at ca. 1053 K. The tubular reactors were wound Incoloy steel tubes (I.D. 4 nm), heated by high-frequency induction. The total pressure in the reactor was slightly above atmospheric.The thermal decomposition mechanism of n-tetradecane, the major alkane in the Solpar mixture, allows the identification of all the primary products (non-zero initial rate of formation) by gas chromatography. Under these experimental conditions, very close to those of industrial stream cracking, secondary products (zero initial rate of formation) were observed and were qualitatively interpreted from elementary steps including the main primary products. This kinetic study also stresses the importance of the new steam cracking reactors calles “millisecond furnaces”, since these reactors produce high yields of light olefins and low yields of monoaromatic hydrocarbons.