The BASF NMP-based butadiene extraction process, licensed by CB&I since 1990, is the preferred technology for the production of high purity 1,3-butadiene from crude C4 cuts. The technology is successfully applied in 41 plants worldwide, with a total capacity exceeding four million tons per year. The NMP-based butadiene process uses n-methyl-pyrrolidone (NMP) as solvent. Unlike the other solvents used for butadiene extraction, the aqueous mixtures of NMP are not corrosive, thereby allowing the use of carbon steel as construction material without the addition of corrosion inhibitors. This process is particularly suitable for C4 streams from high severity cracking where the acetylene levels may be high (>3%). It produces a 1,3-butadiene product of 99.7 wt% purity while recovering more than 99% of the 1,3-butadiene contained in the feed. It also produces a raffinate-1 product that consists of a mixture of butanes and butenes with a butadiene content as low as 40 ppm wt.