Published September 2003
Most of the world's butadiene is obtained as a coproduct of ethylene, especially by the steam cracking of naphtha or gas oil. When co-product butadiene is not sufficient, supplies can be supplemented by material made by the dehydrogenation of n-butenes or n-butane or from ethyl alcohol. Regardless of the source, butadiene must be separated from other C4 hydrocarbons (mainly butanes and butenes). Extractive distillation is the major separation process currently in use.
BASF's process for extractive distillation of butadiene is based on the solvent N-methyl-2-pyrrolidone (NMP). The technology has been on the market for more than 30 years. NMP was originally selected because of the high solubility of butadiene in the solvent. In recent years, effort has been invested in a general revision of the process, based on NMP solvent. In this review, we evaluate the techno-economics of butadiene extraction by the new BASF NMP process. We also provide an update of the economics of the old NMP process for comparison.
