Published May 1982
Butadiene is a major petrochemical commodity with a U.S. consumption of three to four billion pounds per year and a worldwide consumption of nine to ten billion pounds per year. The compound of commercial interest is 1,3-butadiene, CR2=CHCH=CH2. It is a colorless gas normally stored and handled as a liquid under refrigeration and pressure. The isomer, 1,2-butadiene, is of little commercial importance.
Most of the world's butadiene is produced as a coproduct of ethylene, which is obtained by the steam cracking of various hydrocarbons ranging from propane to gas oil. Smaller amounts are produced in the United States by dehydrogenating n-butenes.
Because of its two double bonds, the butadiene molecule is very reactive and it readily forms polymers, which are the main end use for butadiene. A large fraction of butadiene production is consumed in the manufacture of styrene-butadiene rubber (SBR) and other elastomers, most of which are used in tires or other products associated with the automobile industry.
Since publication of the previous PEP report on butadiene in 1972 (Report No. 35Al), there have been no significant new markets for butadiene. The average U.S. annual consumption has remained essentially constant, although there was a marked decline In 1975 because of an overall economic recession, and another one in 1979-80 because of a slump in U.S. automobile production, coupled with the increased proportion of small cars using small, long-wearing radial tires. Estimated butadiene consumption in 1980 was about 3.5 billion pounds.
In 1973 there was a sharp Increase in world crude oil prices and a corresponding increase in the price of butadiene and other hydrocarbons. The high oil cost provided increased incentive to reduce process energy consumption. As a result, there is a continued trend toward ethylene-coproduced butadiene and a trend away from the dehydrogenation processes, which use larger amounts of energy.
Butadiene from n-butane by the Houdry dehydrogenation process has apparently been the least economical process, and few if any Houdry units are still operating in the United States on butane feeds (358670), although some modified Houdry plants may be operating with butene feedstocks. We have not updated our previous evaluation of the Houdry process (PEP Report No. 35, March 1968), since it seems to be attractive only for special circumstances in which n-butane is available at low cost. We have evaluated the Petro-Tex Oxo-D process for the oxidative dehydrogenation of n-butenes. This process is in current use and is available for licensing. Another oxidative dehydrogenation process formerly offered by Phillips is no longer being licensed.
Regardless of the source of butadiene, it must be separated from other C4 hydrocarbons and from various impurities, usually by extractive distillation. We have evaluated the Nippon Zeon process using dimethylfornamide (DMF) solvent, the BASF process using N-methyl-pyrrolidone (NMP), and the Union Carbide process using dimethylacetamide (DMAC). The Shell process using acetonitrile and the Phillips process using furfural as solvents were described in PEP Report 35A1, but they are not currently being licensed.
Other PEP Related Reports: