Lyondell Petrochemical Co., Houston, has developed a one step process to convert normal butylenes to isobutylene, a key component of methyl tertiary butyl ether (MTBE).
MTBE is expected to become the additive of choice among U.S. refiners to blend oxygenated gasolines required by 1990 amendments to the Clean Air Act.
Lyondell Pres. and Chief Executive Officer Bob Gower said the new process could help assure adequate supplies of MTBE to meet U.S. demand for cleaner burning fuels.
Lyondell estimates the capital cost of building a grassroots plant to produce isobutylene with the new process would be less than half the cost of a grassroot plant to produce isobutylene with existing technology starting with normal butane.
Isobutylene is a coproduct of catalytic cracking operations and olefins production. Manufacturers also are beginning to produce on purpose isobutylene by isomerizing butane, then dehydrogenating the isobutane. By starting with normal butylene instead of butane, Lyondell's new process eliminates the dehydrogenation step.
ARCO Chemical Co., an 80% owned subsidiary of ARCO, produces isobutylene by dehydrating tertiary butyl alcohol, which it makes as a byproduct in a propylene oxide process.
Lyondell is less than 50% owned by ARCO.
Gower said enough normal butylene is produced in the U.S. to make the process attractive to other petrochemical manufacturers. Lyondell estimates world normal butylene capacity at about 250,000 b/d.
Isobutylene often is alkylated to produce octane components for gasoline.
"A lot of normal butylenes are coproduced, and there haven't been many uses for them," Gower said. "Our new process provides a good upgrade of the material."
Lyondell has successfully tested the new process in a pilot unit. Following a large scale demonstration this year, the company expects to build a commercial unit at Channelview, Tex., where it operates a petrochemical complex.
The company also plans to license the technology to other petrochemical producers.
Lyondell, the fourth largest U.S. olefins producer, produces MTBE using isobutylene coproduced through olefins and refining processes.
Gower said Lyondell could divert enough normal butylene from other uses at the Channelview plant to produce isobutylene feed for a 7,500-10,000 b/d MTBE unit. Also at Channelview, Lyondell produces about 233 million gal/year of methanol, another key MTBE component.
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