Shortages of butadiene

One major problem with the availability of polychloroprene in the recent past has been the availability of butadiene monomer. Because of the gradual switchover from naphtha feedstocks from petroleum to ethane feedstocks from natural gas in the production of ethylene for the plastics industry, there are fewer C4 streams available for butadiene production. Ethylene plants are gaining significant economic savings by making this feedstock conversion from naphtha to ethane. This has resulted in significant shortages of butadiene to the rubber industry. However, there is optimism now that butadiene will be more available than before because... 

In 2008 there were significant shortages of butadiene monomer. This was because the yields of butadiene from ethylene plant production were down at that time because these plants were running on lighter crudes rather than heavy crudes (which give a higher yield of butadiene monomer). Because of this change in yield, many synthetic rubber plants were on allocation. 

During World War II a shortage of natural rubber in the United States prompted an intensive program to produce synthetic rubber. Most synthetic rubbers (called elastomers) are made from petroleum products such as ethylene, propylene, and butadiene. For example, chloroprene molecules polymerize readily to form polychloroprene, commonly known as neoprene, which has properties that are comparable or even superior to those of natural rubber ... 

With the outbreak of war in 1939 and the consequent shortage of natural rubber in the industrial West, the introduction of the copolymer of butadiene and styrene, then known as Buna or GR-S, as an almost total replacement for natural rubber, would not have been possible without carbon black. It may be stated, with little likelihood of contradiction, that no other product exists which contributes as much strength and abrasion resistance to noncrystallizing rubbers, while maintaining to a large extent their desirable elastic properties, as does carbon black. 

Blends of butadiene-acrylonitrile copolymer rubber (nitrile rubber or NBR) and PVC are among the oldest known examples of commercial elastomer/ thermoplastic blends. The shortage of natural rubber during World War II stimulated research in the USA on the compounding and modification of synthetic polymers to produce rubber-like materials. An outcome of this research was the commercial introduction of NBR/PVC blends by B.F. Goodrich in 1947 under the trade name of Geon Polyblends [Pittenger and Cohan, 1947]. The blend showed improved ozone resistance and melt processability compared to the nitrile rubber (Table 15.12). 

In 1943, polystyrene could not be economically produced on a commercial basis. However, the shortage of natural rubber from the South Pacific because of World War II (3) led to the increased demand and the development of styrene-butadiene rubber (SBR) in the United States during the 1940 s. Thus, styrene was produced by many producers. 

A general shortage of n-butenes has led to the development of two processes in which n-butane is the starting point for the production of butadiene. In the Houdry process, which is the more important of the two methods, dry butane is passed over a catalyst of 15—20% chromia on activated alumina at an initial temperature of 620—650°C and a pressure of 0.2 atmosphere. After 7—15 minutes the temperature falls and the catalyst becomes coked the feed is then switched to a fresh reactor. The coke is burnt off the spent catalyst which is thus re-activated and re-heated ready for the next cycle. Butadiene is recovered from the product gas by the methods described above. In this process, the conversion is about 25% and the selectivity about 80%. 

While natural rubber began as the basis for automobile tires, synthetic rubber products replaced natural rubber - partly as a consequence of the rubber shortage of World War II. Synthetic rubber products include styrene-butadiene rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), nitrile rubber, neoprenes, polysulfides, polyacrylate rubber, and a host of other products with 65% of all SBR... 

Chemical Uses. In Europe, products such as ethylene, acetaldehyde, acetic acid, acetone, butadiene, and isoprene have been manufactured from acetylene at one time. Wartime shortages or raw material restrictions were the basis for the choice of process. Coking coal was readily available in Europe and acetylene was easily accessible via calcium carbide. 

Butadiene production from these dehydrogenation processes did not continue beyond the 1960s, as butadiene from steam cracking of naphtha became available. Later, however, from about 1990, as butadiene and butene shortages developed, several commercial processes were revived. 

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