n e w s o f t h e w e e k 5$$ '

tubule presumably is capped with half of a C36 fullerene, a highly reactive cage.

The limit of energetically stable nanotubes is reached with the 4-Â tu­bule, which is thought to be helmeted by half of a C20 fullerene. Earlier this year, a German team reported observ­ing the elusive C20 cage in the gas phase [C&EN, Sept. 11, page 5; Nature, 407 , 60 (2000)]. Calculations suggest that "because of the increased curvature en­ergy, nanotubes smaller than 4 A are ex­tremely unstable," Tang notes.

Asked to comment on the Chinese group's paper, Pulickel M. Ajayan, an as­sociate professor of materials science and engineering at Rensselaer Polytechnic In­stitute in Troy, N.Y., says the synthetic method using the zeolite is attractive. If the tubelike entities observed in their transmission electron microscope (JEM) images are indeed SWNTs, Ajayan tells C&EN, "it is quite amazing that such small structures can form in the pores."

However, he adds, the TEM image published in the Chinese group's paper "is not of good quality," and the objects could, for example, be "two-layer graph­ite strips" often seen in images of par­tially graphitized structures, he sug­gests. "I am still not very convinced that they are SWNTs."

Tang responds that the group did consider the possibility of double sheets of graphite, but that other experimental and image simulation results not report­ed in the Nature paper eliminated this possibility. "We believe that our results are quite convincing," he says.

Ron Dagani

Chemical Sales Up, Earnings Mixed In Third Quarter

As expected, higher raw materials costs are taking their toll on third-quarter earn­ings at major chemical companies. De­spite rising prices for most chemical products and increased sales at many companies, earnings declined compared with the same quarter in 1999 for eight of the 15 largest U.S. chemical producers.

However, at companies where earn­ings did increase, the results were often very good. For instance, Eastman Chemi­cal had the largest percentage increase. Earnings from continuing operations, ex­cluding significant unusual items, rose 184% to $77.8 million on a 17% increase in

Sales rose for 10 of 15 but only seven

Air Products Crompton Dow Chemical DuPont Eastman Chemical

FMC W.R. Grace Great Lakes Chemical Hercules IMC Global

Lubrizol Praxair Rohm and Haas Solutia Union Carbide

major chemical companies, reported increased earnings

THIRD-QUARTER 2000

Sales Earnings*

($ millions)

$1,449.1 738.5

5,514.0 6,445.0 1,387.0

919.2 394.7 403.1 815.0 483.4

424.0 1,275.0 1,677.0

774.0 1,637.0

$139.4 21.6

328.0 537.0 77.8

56.5 34.1 25.0 14.0 1.8

22.3 122.0 84.0 25.0 29.0

Change from 1999

Sales Earnings

16% 48 17 0

17

-11 6 8

-2 -7

-2 9 6 6 9

a After-tax earnings from continuing operations, excluding significant nonrecurring earnings as a percentage of salei >.

20% 43

3 -14 184

31 4

-27 -77 -88

-33 9

-6 -59 -41

Profit

2000

9.6% 2.9 5.9 8.3 5.6

6.1 8.6 6.2 1.7 0.4

5.3 9.6 5.0 3.2 1.8

and extraordinary items.

margin6

1999

9.2% 3.0 6.8 9.7 2.3

4.2 8.8 9.1 7.4 2.8

7.8 9.6 5.6 8.3 3.3

b After-tax

sales to $1.39 billion. Earnest W. Deaven-port Jr., the company's chairman and chief executive officer, credited East­man's ongoing emphasis on cost reduc­tions and increased selling prices for their positive impact on third-quarter earnings. But better markets also played a role, with operating income for the chemical sector up 50% and almost tri­pling for polymers as the polyethylene terephthalate business improved.

IMC Global represents the other side of the coin. Its earnings fell 88% to just $1.8 million on a 7% drop in sales to $483 million. The company is hampered because most of its products are sold into a relatively poor farm economy. During the quarter, for instance, IMC Global temporarily shut down, then only partially resumed, production of phosphates—its Achilles heel during the three-month period—at its Louisi­ana operations.

The largest dollar decline was for in­dustry leader DuPont, where earnings fell 14%, or $88 million, to $537 million on $6.45 billion in sales, unchanged from the year-earlier quarter. Segments that suffered during the quarter includ­ed seeds, fibers, and pharmaceuticals.

Dow Chemical, the number two chemical company, meanwhile record­ed a modest 3% increase in earnings to $328 million. But that was on a 17% rise in sales to $5.51 billion. The company noted that its energy and feedstock costs rose 46% during the quarter.

Union Carbide, the company that Dow is trying to acquire, saw its earnings de­cline 41% to $29.0 million, despite a 9% im­provement in sales to $1.64 billion. Chair­man and CEO William H. Joyce put the blame on higher raw materials costs and weakening average selling prices from prior quarter levels for polyethylene and ethylene glycol.

William Storck

How Methanol Turns Into Olefins Like a good mystery? Try explaining this one. A chemist sets up a catalytic reactor and adds a reactant. Nothing happens. A few minutes later, under the same conditions of temperature and pressure, the chemist adds an addition­al aliquot of reactant to the same cata­lyst and voilà—100% conversion.

Chemists at the University of South­ern California have an explanation. The catalyst, a porous mineral, is undergo­ing an induction period, they say. Or­ganic reactants diffuse into the mate­rial's cavities and react. The newly formed structures then serve as active sites that cause subsequent doses of re­actant to undergo catalytic conversion.

Based on studies using a recently de­veloped analytical technique, the USC re­searchers report that methylbenzenes (up to pentamethylbenzene) are the or-

10 NOVEMBER 6, 2000 C&EN

ganic structures that lie at the center of the mechanism for methanol-to-olefin conversion chemistry on an alumino-phosphate catalyst known as HSAPO-34 [/. Am. Chem. Soc, 122, 10726 (2000)].

The study was conducted by USC chemistry professor James F. Haw, graduate student Weiguo Song, and postdoctoral researcher Catherine S. Heneghan and by John B. Nicholas, a computational chemist at Pacific North­west National Laboratory (now at Gen-entech, South San Francisco).

Methanol-to-olefin chemistry is on the verge of becoming a key area of the chemical industry because of the enor­mous demand for polyethylene and oth­er polyolefins, Haw asserts. Ideally, nat­ural gas would be converted to metha­nol and then to olefins and polyolefins using efficient and environmentally be­nign procedures. But manufacturers won't take that route until all legs of the trip are well defined.

Understanding the mechanism of methanol conversion to hydrocarbons has remained a key challenge in funda­mental catalysis research, Haw says. But thanks to the group's pulse-quench meth­od for analyzing catalysts caught in the act of mediating reactions, pieces of the puzzle are beginning to fall into place.

Using high-speed computer-con­trolled valves, the USC group delivers methanol to a preheated quantity of HSAPO-34 and then abruptly shuts off the reaction after a preselected period by cooling the catalyst with frigid gas.

The cagelike topology of HSAPO-34, a silico aluminophosphate, is char­acterized by voids of roughly 1.0 nm by 0.67 nm interconnected through small windows (0.38 nm) that pre­vent the flow of isobutene and larger molecules. (For clarity, only a skele­ton of alternating aluminum and phosphorus is shown.)

The fossilized evidence is then exam­ined with solid-state nuclear magnetic resonance methods.

The researchers find that after a brief induction phase in which methylben-zenes are assembled in a ship-in-a-bottle fashion inside the catalyst's small open­ings, methanol is efficiently converted to ethylene, propene, and other hydrocar­bons. The group also observes that poly-cyclic aromatics deactivate the catalyst.

'The paper is quite thought provok­ing," says Daniel Raftery, an associate professor of chemistry at Purdue Uni­

versity. It's interesting that the interme­diate is a much larger molecule than ei­ther the reagent or products, he adds.

William S. Millman, a division direc­tor in the Department of Energy's Office of Basic Energy Sciences in German-town, Md., notes that it is difficult to pre­dict how the study's results will be ap­plied. "But it is clear that, without a molecular-level understanding of the re­lationship between desired products and catalyst deactivation products, progress in this area will be haphazard."

Mitch Jacoby

Poultry Antibiotics Pose Human Threat The Food & Drug Administration wants to ban two poultry antibiotics, members of a family of drugs also used in humans, saying their use increases the risk that humans will become infected with resis­tant bacteria. This is the first time FDA has proposed banning any antibiotic because of bacterial resistance. It is also the first time FDA has proposed withdrawing approval for an antibiot­ic used in the livestock industry.

The two antibiotics are fluoro­quinolones: enrofloxacin made by Bayer Corp. and sarafloxacin made by Abbott Laboratories. Similar fluo­roquinolones used in humans, FDA says, are considered "one of the most valuable antimicrobial drug classes because of their spectrum of activity, safety, and ease of adminis­tration" when they work. But some strains of bacteria are now resistant to the drugs.

Abbott Laboratories says it will with­draw sarafloxacin from the market im­mediately. Bayer is considering wheth­er to request a hearing to contest the ban on enrofloxacin.

According to an FDA statement, the agency based its decision on several fac­tors. Most important was that using fluoroquinolones in poultry causes the development of fluoroquinolone-resis-tant pathogens in poultry. These patho­gens—Campylobacter bacteria—are transferred to humans when they eat undercooked poultry.

FDA's decision also stems from a risk assessment completed earlier this year that concluded some 11,500 people infected with Campylobacter would have a fluoroquinolone-resistant illness re­sulting from fluoroquinolone use in poultry. Some of these patients, espe­cially children and the elderly, likely

would have prolonged illness and com­plications that would be life threatening.

Because treating individual chickens or turkeys with antibiotics is too expen­sive, fluoroquinolones are added to the drinking water of the entire flock. Ac-

Chickens raised in close quarters commonly are administered antibiotics in water.

cording to FDA's risk assessment, about 24% of chickens being processed are contaminated with fluoroquinolone-resistant bacteria.

Fluoroquinolones were approved for use on poultry and cattle in the mid-1990s, and the incidence of fluoroquino­lone-resistant bacterial infections in hu­mans has risen dramatically since then. Polymerase chain reaction techniques have allowed epidemiologists at the Cen­ters for Disease Control & Prevention (CDC), Atlanta, to trace exact subtypes of Campylobacter from chickens to infected hospital patients. Consequently, CDC has been urging FDA for several years to ban fluoroquinolone use in poultry.

Individuals and companies affected by the proposed ban may request a hearing by Dec. 1 and submit data sup­porting the request by Dec. 31.

Bette Hileman

NOVEMBER 6, 2000 C&EN 1 1