Kinetics and modelling of heptane steam-cracking

The kinetics and product distribution during the cracking of heptane in the presence of steam were investigated. The experiments were performed in a flow reactor under atmospheric pressure in a temperature range of 680–760°C with a mass ratio of steam to heptane of 3: 1. The overall decomposition of heptane is represented by a first-order reaction with activation energy of 249.1 kJ mol−1 and a frequency factor of 3.13 × 1013 s−1. The reaction products were analysed using gas chromatography, the main product being ethylene. The molecular reaction scheme, which consists of a primary reaction and 24 secondary reactions between primary products, was used for modelling the experimental product yields. The yields of ethylene and hydrogen were in good agreement; however the experimental yields of propylene were higher than the predicted yields.