COUPLING OF THERMAL-CRACKING WITH NONCATALYTIC OXIDATIVE CONVERSION OF ETHANE TO ETHYLENE

Homogeneous thermal cracking of ethane, which is an endothermic and he nce energy-intensive process, was carried out in the presence of limit ed 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 v elocity of 2,000 - 11,000 h(-1)). The influence of a sulfur additive i n the feed and reactor material on the process performance was also in vestigated. Noncatalytic oxycracking of ethane in the presence of limi ted 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 achiev e 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-e fficient, with a drastic reduction in external energy requirement and coke formation. By manipulating the process conditions, particularly t he temperature and O-2/C2H6 ratio, the overall process can be made alm ost thermoneutral, mildly exothermic, or mildly endothermic.