reactions to taking pyridostigmine bro mide tablets. They were in the same area on the same day as Czech troops who reported the detection of nerve gas and mustard gas. Haley's group believes the syn dromes are variations of a rare nervous system disorder called organophosphate-induced delayed polyneuropathy. Some pesticide workers have this disor der, and victims of the Tokyo subway chemical weapons attack also may be found to have it. Lashof believes these two groups may be good subjects for future studies. Lois Ember
Carbides catalyze methane reforming Chemists in England have serendipitously discovered that two group 6 transitionmetal carbides catalyze the conversion of methane, or natural gas, to carbon mon oxide and hydrogen. The mixture, known as synthesis gas, or syngas, is used indus trially for the synthesis of methanol, as a source of hydrogen for ammonia manu facture by the Haber process, and to pro duce synthetic fuels by the Fischer-Tropsch reaction. Inorganic chemistry professor Malcolm L. H. Green and graduate students Andrew P. E. York, John B. Claridge, Attila J. Brungs, and Shik Chi Tsang, at Oxford Uni versity, found that molybdenum carbide (Mo2C) and tungsten carbide (WC) are ac tive and stable catalysts for methane re forming at slightly elevated pressures [Chern. Commun., 1997, 39]. "We stumbled across this observation
Green: surprising discovery
by accident about four years ago," Green tells C&EN. "But the discovery has been locked up in patenting until now." Using carbide catalysts for methane oxidation is counterintuitive, he ex plains. Carbides are normally very reac tive toward the oxidants—water, carbon dioxide, and oxygen—that reform meth ane. But under slightly elevated pres sures, the active metal carbide phase is stabilized. "This is very surprising, and we cannot fully account for it," he says. Green, who is the recipient of the 1997 American Chemical Society Award in Organometallic Chemistry (see page 30), points out that nickel catalysts are currently used for conversion of methane to syngas by steam reforming or dry reforming. Both these processes are endothermic, whereas production of syngas by partial oxidation of methane using oxygen is exothermic. When nickel is used to catalyze the re forming of methane to syngas, deposits of carbon deactivate the catalyst and clog up the reformer tubes. To prevent this, large excesses of oxidants are used. But this in turn leads to ratios of carbon monoxide and hydrogen that are not optimal for pro duction of methanol and synthetic fuels. In contrast, the carbides catalyze methane reforming by all three oxidation routes using only stoichiometric amounts of the methane and oxidant feedstocks. The Oxford group did not observe carbon deposition. "The generation of synthesis gas from hydrocarbons, either catalytically or noncatalytically, is of considerable impor tance, and is likely to remain so. New cat alysts for this process are thus of interest," comments Peter W. Lednor, senior re search chemist at Shell Research & Tech nology Centre, Amsterdam. "An intriguing feature of the [current] work is the stabili ty of the carbide catalysts in methane oxi dation reactions at elevated pressure." The Oxford project is sponsored by an international consortium of industrial com panies concerned with natural gas conver sion. The consortium is managed by the Canada Centre for Mineral & Energy Tech nology (CANMET), Energy Technology Centre, in Ottawa, Ontario. CANMET is part of Natural Resources Canada, a de partment of the Canadian government. "Synthesis gas is an important industri al commodity for subsequent chemical and fuel manufacturing," consortium man ager Safaa Fouda tells C&EN. "The devel opment of noncoking—that is, low carbon deposition—catalysts is important to ensure long-lasting performance." Michael Freemantle
Spectra reveal superconductor, monolayer interaction Chemists have developed a way to probe self-assembled monolayers on the surfaces of high-temperature superconductors. The technique, which uses off-the-shelf Raman spectrometers to acquire vibrational spec tra of the monolayers, could allow a better understanding of the adsorption and selfassembly process and help researchers better tailor the properties of high-temper ature superconductors. The self-assembled monolayers may, among other roles, act as a protective coat, preventing the hygroscopic and highly re active superconductors from degrading in the presence of air and moisture. But char acterizing the interactions between a monolayer and the surface of a hightemperature superconductor through vibra tional spectroscopy is difficult. The small number of molecules in one layer and the poor optical properties of the superconduc tor combine to give a very weak signal.
Gold nanoparticles rev up monolayer signals
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