Technology Type

Process Summary

1,3-butadiene is generally recovered from mixed C₄ hydrocarbons which are consisted of 1,3-butadiene, 1,2-butadiene, butanes, butenes and acetylenes. The 1,3-butadiene separation is accomplished by extraction from the mixed C₄ hydrocarbons. There are several extraction processes and the processes are similar to each other basically. Each process to extract the butadiene has a unique extraction process depending on the solvent being used such as N-methylpyrrolidone (NMP), dimethylformamide (DMF), or acetonitrile (ACN), to extract the 1,3-butadiene from the crude C₄ mixture.

Features

The Butadiene Extraction Unit of the extraction process is designed to separate the mixed C₄ hydrocarbons into two primary product streams—Crude 1,3-Butadiene and Raffinate—using a solvent. The extraction processes are mainly consisting in Extractive and Conventional distillations, Solvent Stripping Section and Distillation Section.

Extractive and conventional distillation Section

Mixed C₄ hydrocarbon vapor stream is fed to the extractive and conventional distillation and crude 1,3-butadiene stream and raffinate stream are separated in the section. 

• In the first extractive distillation section, the butanes and butenes (C₄ raffinate) are removed in the overhead.
• The overhead stream of the second extractive distillation column concentrates the 1,3-butadiene for downstream purification.

Solvent Stripping Section

The solvent laden with C₄ hydrocarbons from the extractive and conventional distillation section, which is solvent-rich, is stripped into lean solvent in this section.

• The lean solvent is returned to the extraction and conventional distillation section.
• To minimize energy consumption, the hot lean solvent from the stripper is utilized as a heating medium at several heat exchangers before entering the extraction column.

Distillation section

The crude 1,3-butadiene contains propyne, 1,2-butadiene and C₅ components and 1,3-butadiene:

• Butadiene end product is separated and purified passing through several conventional columns, increasing the 1,3-butadiene concentration from 95 – 98% to at least 99.5% for the final product.
• Light components with propyne and heavy components with 1,2-butadiene are separated from the columns.

References

1. Toyo Engineering Korea Ltd., Butadiene (BD). (accessed 9^th Feb 2022)
2. Pippa Luck, 14^th Jul 2021, Increased reliability in butadiene production, Hydrocarbon Engineering.