α-Olefins produced with 100% selectivity - C&EN Global Enterprise

"It certainly has the potential to be a new commercial α-olefin catalyst," comments Eduardo J. Barak, an α-olefin specialist at Chevron, "but a lot ...
0 downloads 0 Views 266KB Size
While countries talk, company acts Following up on a pledge made in May, British Petroleum Chief Executive John Browne last week outlined internal actions the company is taking to address problems posed by global warming, as well as some "unlikely bedfellows" projects being undertaken with industrial critics such as the Environmental Defense Fund (EDF) and the Nature Conservancy. Speaking in Berlin, Browne said that by next year BP will begin to measure and report the volumes of carbon dioxide emitted from its operations and will set reduction targets over the following two years. They will be "firm, realistic targets" to be independently verified and published, Browne said. And in coordination with EDF, the company is developing an internal emissions trading system to achieve the targets at the lowest practical cost Among its external projects, BP has begun work with the Pacific Northwest National Laboratory, Richland, Wash., and the Electric Power Research Institute, Palo Alto, Calif., on a low-carbon technology program that will identify the technical advances in the use of energy that can do most to respond to the challenge of climate change. The company is also involved in a project involving American Electric Power, which is a utility company in Columbus, Ohio; the Nature Conservancy; and the government of Bolivia to plant roughly 2 million acres of trees in Bolivia, and it wants to establish a similar project in Eastern Europe. "We can't solve the whole problem," Browne concluded, "but we can make a contribution, and we can test, within our own systems, some of the processes that might have a wider public application." Patricia Layman

Romm, DOE acting assistant secretary for energy efficiency and renew able energy. Some of the technologies that can achieve large carbon dioxide reductions at little cost include deploying advanced turbines, which have an overall efficiency of 80 to 90%, in industry: making use of cellulosic ethanol derived from agricultural and forestry waste in transportation: converting coal-fired power plants to natural gas: and cofiring coal with biomass. Large energy savings could also come from utilizing the waste heat from power production, Romm explains, noting that the U.S.

throws away as much waste heat from utilities as all of the energy used by Japan. The Global Climate Coalition, a lobbying group for the fossil fuel industry and some other manufacturing interests, disagrees sharply with DOE s conclusions. On Oct. 1. it released a report by the economic consulting firm WEEA Inc., Eddystone. Pa., which concludes that stabilizing emissions would cost $2,061 per year per household by 2010. "What this report tells us loud and clear is that the Administration is fiat-out wrong when it says we could reduce greenhouse gas emissions effortlessly without any impact on our economy," says coalition president Gail McDonald. On the other hand, John Glimmer, a Conservative member of the British Parliament, told reporters in Washington, D.C., last week that he deplores the idea of the U.S. merely stabilizing its carbon emissions. If the U.S. pursues a policy of stabilization, it will be propping up dirty industries and old technologies, while the rest of the developed world cuts emissions below 1990 levels, notes Gummer, who was Secretary of State for the Environment under Prime Minister John Major. "As a result, the U.S. will get behind the times," he says. "The quicker you adopt new technologies, the more you will be able to compete," he notes. Bette Hileman

(/•Olefins produced with 100% selectivity A newcomer to the metallocene family works at much lower pressures and temperatures than presently used nickel or aluminum-based catalysts to convert ethylene to 1-alkenes—and with a reported 100% selectivity. The boratabenzene catalyst may provide a cheaper and safer route to production of the alkenes, known commercially as a-olefins, which are widely used in the manufacture of plastics, detergents, and lubricants and are produced in billions of pounds per year. 'It certainly has the potential to be a new commercial a-olefin catalyst," comments Eduardo J. Barak, an a-olefin spccial-

_ B /OCH 2 CI-

^OCH 2 CH 3 Ethoxy boratabenzene

ist at Chevron, "but a lot of work must be done first to answer questions about the catalyst's activity, lifetime, and expense." The new catalyst consists of a zirconium dichloride center sandwiched between six-membered rings. The rings are composed of five carbon atoms and a boron atom. An cthoxy group is attached to each boron atom. The catalyst was prepared by Guillermo C. Bazan, associate professor of chemistry at the University of Rochester, and graduate students Jonathan S. Rogers and Caroline K. Sperry [/. Am. Cbem. Soc, 119, 9305 (1997)]. "The thing I find most interesting about this catalyst is the incredible [olefin] purity," says Richard A. Kemp, a senior research scientist at Union Carbide. Kemp notes that commercial a-olefin catalysts—like the nickel-based compounds Shell uses or the alkylaluminum catalysts used by Chevron and Amoco— may leave percent levels of impurities in the alkene product. By contrast, Bazan's group reports 100% selectivity under some reaction conditions. The Rochester chemists compared the catalytic properties of the ethoxy boratabenzene compound to one in which the ethoxy group is replaced by a phenyl ring. In general, the phenyl-substituted compound showed greater reactivity but lower selectivity. Under one set of conditions, the cthoxy compound produced 100% 1-alkenes, while the phenyl analog produced a mixture of 1-alkenes, 2-alkenes, and 2-alkyl-1-alkenes. "The unusual thing about this catalyst," Bazan comments, "is that unlike typical metallocenes, which convert ethylene to higher alkenes and then make alkene dimers and trimers and so on, this catalyst can be designed to make a-olefins and stop." Bazan proposes that the high selectivity results from the catalyst's electronic properties—which are finely tuned by the presence of an ethoxy group—and the mild reaction conditions—60 °C and 1 atm of ethylene. "The big challenge now is to make boratabenzene compounds in a cheaper and more streamlined way," Bazan says. "Currently, it takes several steps to make the compound," he notes, whereas triethylaluminum, the catalyst used by Chevron and Amoco, can be made in one step from aluminum, hydrogen, and ethylene. To be a commercial success, the new catalyst will have to be cost efficient. Chevron's Baralt agrees. That may require making a recyclable catalyst in high yield from less expensive reagents. Mitch Jacoby OCTOBER 6, 1997 C&EN

11