Coupling of thermal cracking with noncatalytic oxidative conversion of ethane to ethylene

Homogeneous thermal cracking of ethane, which is an endothermic and hence energy-intensive process, was carried out in the presence of limited O-2 under different process conditions (at 600 degrees-850 degrees C; O-2/ethane ratio of 0-0.2; H2O/ethane ratio of 0 - 3.3; and space velocity of 2,000 - 11,000 h(-1)). The influence of a sulfur additive in the feed and reactor material on the process performance was also investigated. Noncatalytic oxycracking of ethane in the presence of limited O-2, greatly enhances not only the total conversion of ethane but also the conversion of ethane by purely thermal cracking. This process also occurs at a much lower contact time than that required to achieve the same conversion for the thermal cracking process. Also, both the exothermic oxidative conversion and the endothermic thermal cracking of ethane occur simultaneously, which makes this process very energy-efficient, with a drastic reduction in external energy requirement and coke formation. By manipulating the process conditions, particularly the temperature and O-2/C2H6 ratio, the overall process can be made almost thermoneutral, mildly exothermic, or mildly endothermic.