Published: April 1996
Most of the world's butadiene is obtained as a by-product of ethylene manufacture. The growing butadiene surplus resulting from the increasing liquid feedstock-based ethylene production in recent years has led to the shutdown of most on-purpose dehydrogenation plants. As the surplus continues with the higher demand growth rate for ethylene, processes for the selective and total hydrogenation of steam cracker C4s are being developed to dispose of the excess butadiene. Western European ethylene cracker operators favor selective hydrogenation to butenes, and they often build such units without corresponding butadiene extraction units. In contrast, total hydrogenation to butane for recycle to the steam cracker is preferred in the Asia-Pacific region, where the process is often used along with a butadiene extraction unit to improve butadiene inventory flexibility.
This report contains the process economics for butadiene recovery from steam cracker C4s using dimethylformamide (DMF) and N-methylpyrrolidone (NMP) extractive distillation. We have also developed process economics for the selective and total hydrogenation of steam cracker C4s. Results show that extractive distillation and hydrogenation economics depend heavily on raw material valuations, which are location-specific.