NEWS OF THE WEEK
METHANE CONVERSION Two new direct oxidation schemes found esearch groups in California and ways to eliminate production of water by distillation. The group has shown Minnesota, working indepen- and carbon dioxide as well as undesir- by tracer studies that the methanol prodently, have developed two new able intermediates, and finding substi- duced definitely comes from oxidation approaches to the catalytic conversion of tutes for precious-metal catalysts. of methane, and not from a carbonamethane—one yielding methanol and In one of the new approaches, a group ceous contaminant. the other synthesis gas, a mixture of at Catalytica headed by research chemist Conversion of methane to methanol carbon monoxide and hydrogen. Nei- Roy A. Periana uses mercuric ions to se- with reduction of sulfuric acid to sulfur ther approach is ready for commercial lectively catalyze conversion of methane dioxide is, of itself, insufficient for ecoapplication, but both offer new insights to methanol via a methyl bisulfate inter- nomical synthesis of methanol. But sulinto the complex chemistry of methane mediate in yields up to 43%. The reac- furic acid is a cheap commodity chemiconversion. tion occurs in a homogeneous system at cal, prepared by oxidation of sulfur diPapers describing the new approaches 180 °C. Periana believes this is the first oxide with enriched air, via sulfur appear in last week's Science [259, 340 instance in which Hg(II) is used in elec- trioxide. This leads to a potentially pracand 343 (1993)]. One group worked at trophilic reactions of methane. The work ticable scheme to produce methanol. Catalytica Inc. in Mountain View, Calif. was funded in a joint project between In the reaction sequence for this chemThe other group worked at the Universi- Catalytica and a subsidiary of Japan's istry, sulfuric acid functions as an oxyty of Minnesota in Minneapolis. gen transfer agent. The net transformaMitsubishi Oil Co. Direct conversion of methane has Keys to this chemistry are the novel tion is selective oxidation of methane to been a scientific and technological prob- use of Hg(II) as a catalyst for methane methanol with molecular oxygen. Perilem at least since the 1920s. Oil shortag- oxidation through an electrophilic dis- ana and his group believe that this repes in the U.S. caused by political prob- placement reaction, and production of resents a significant improvement over lems in the Middle East during the 1970s the monoethyl ester of sulfuric acid as previous developments. The Hg(II)led to an almost panic drive to develop a precursor for methanol. It is vital that sulfuric acid system provides an impora broad-based industrial C-, chemistry this precursor be less reactive than the tant precedent for developing true catabased on methane and synthesis gas. methane. The methyl bisulfate solution lytic systems for selective low-temperaHowever, few immediate results were of produced in the reaction can easily be ture oxidation of methane to methanol. The role of Hg(II) emerged from the commercial importance. hydrolyzed, and methanol separated researchers' previous work inNevertheless, from these efforts volving the stoichiometric reacemerged an ongoing worldwide tion of methane with mercuric attempt to develop processes for Catalytica methane oxidation triflate in triflic acid at 180 °C direct conversion of methane. model has three key steps This reaction results in an almost Probably the most notable have quantitative yield of methyl tribeen oxidative coupling of methflate, which is subsequently reane to produce olefins, and a produced to mercurous triflate and cess for glycol production. Activation not metallic mercury. The reacIn recent years, new political Reoxidation tion proceeds in 100% sulfuric and environmental concerns have acid to produce the correspondadded to commercial interest in diing methyl ester. It is catalyzed rect methane conversion. Profligate by mercuric ions, with sulfuric flaring of methane in the Middle acid as the oxidant. And sulfur East, for example, now is perceived dioxide is coproduced. as not only a great waste of an imThe second new process has portant resource but also an unbeen developed under the direcnecessary contribution to carbon tion of chemical engineering prodioxide loading of the atmosphere, fessor Lanny D. Schmidt at the with no redeeming virtues. Functionalization University of Minnesota. He and If methane could be directly Daniel A. Hickman, now at Dow converted, via catalysis, a number Chemical, produce synthesis gas of problems could be solved. 0.5 S0 2 in a nearly two-to-one carbon Even so, other vexations would Used with permission of American Association for the Advancement of Science monoxide/hydrogen ratio by diremain—for example, devising [Science, 259, 340 (1993)], copyright 1993
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rect catalytic oxidation of methane using oxygen or air over platinum or rhodium surfaces. Feed gases are near room temperature, and reactor residence times are short. The reaction is known to be entirely a surface reaction, because reactions in flames would be homogeneous and produce little hydrogen. The studies at Minnesota were conducted in an adiabatic, tubular reactor containing a plug of porous alumina foam impregnated with platinum or rhodium salts, up to a loading of 20% by weight. The results show that rhodium gives consistently higher selectivities to hydrogen, lower temperatures, and higher conversions than does platinum. A model of the process has been constructed that accounts for all the known parameters. The initial step is dissociative adsorption of methane, in which all carbon-hydrogen bonds are broken. All the data fit the model equations well. The net result is that production of syngas over noble-metal catalysts is possible in very high yields. Conversion of methane is almost complete, and selectivity for carbon monoxide and hydrogen is more than 90%. Joseph Haggin
Canadian woman heads UN environment agency Elizabeth Dowdeswell is scheduled this week to become the first woman and second Canadian to head the 21-year-old United Nations Environment Program (UNEP). Dowdeswell takes the reins as executive director from Mostafa K. Tolba, an Egyptian, who retired after 17 years in that post. UNEP's first head was Maurice Strong, who organized and chaired the Earth Summit in Rio de Janeiro last year. Dowdeswell takes over an organization headquartered in Nairobi, Kenya, with a 1992-93 budget of $150 million (the U.S. contribution for these two years is nearly $40 million). It has more than 400 ongoing projects in six priority areas: • Atmospheric issues, especially climate change, ozone depletion, and acid rain. • Hazardous waste and toxic chemicals. • Fresh water supply and quantity. • Pollution and coastal zone management of oceans and coastal areas.
system—especially those with "the veneer of environmental protection." In what she terms the "sustainable development jigsaw puzzle," UNEP "will choose what it can do and ... can do well, and it will do it well." And more so than in the past, it will cooperate with governments, other UN agencies, industry, environmental groups, and individuals. Dowdeswell sees UNEP's mission as a convergence of science, public policy, and social consensus. She takes as her working motto the words to her of an Inuit colleague: "I want to cause constructive damage to the status quo." Until this year, she served as assistant deputy minister at Environment Canada (equivalent to the U.S. Environmental Protection Agency). She concurrently directed Canada's weather and atmospheric agency, the Atmospheric Environment Dowdeswell: UNEP as agent of change Service, where she was an innovative manager who integrated economic devel• Land degradation, especially de- opment goals with the agency's research functions. Before joining Environment sertification and deforestation. Canada, she held several government po• Loss of biological diversity. At a briefing in Washington, D.C., sitions in Saskatchewan. She also served, until this month, as sponsored by the World Resources Institute, Dowdeswell outlined in broad Canada's permanent representative to the strokes her plans for UNEP. She hinted World Meteorological Organization. And that the organization will move its focus she has been the Canadian chairman of from environmental protection to sustain- the U.S.-Canada International Joint Comable development, the theme of the Earth mission's Great Lakes Water Board. Dowdeswell has a reputation as an inSummit. She strongly believes "UNEP can be a spired public speaker on public policy very effective instrument in translating and environmental issues and as a conwhat [sustainable development] means sensus-builder par excellence. The latter into some form of action.,/ She plans to trait was evident during pre-Earth Sumtransform UNEP into an "agent of mit planning sessions for the Convenchange/7 one that will challenge "ecolog- tion on Climate Change. Lois Ember ically blind programs" within the UN
Monsanto to buy Chevron's Ortho pesticide line Monsanto intends to bolster its lawn and garden pesticide business by acquiring the Ortho products line from Chevron. Under a letter of intent signed earlier this month, Monsanto plans to buy the Ortho business for about $400 million. Ortho, a division of Chevron Chemical, has annual sales of more than $250 million and about 580 employees. The purchase would add to Monsanto7 s home and garden business represented by Greensweep, a firm acquired by the St. Louis-based producer in 1988. Monsanto is releasing no details beyond the projected purchase price, since it is still negotiating with Chev-
ron. But it hopes to complete the deal during the first quarter this year. Last September, Chevron announced it was seeking offers for the Ortho business as part of its 'long-term strategy to evaluate noncore businesses to determine if they have greater value to other companies" (C&EN, Sept. 14, 1992, page 19). At that time, John E. Peppercorn, president of Chevron Chemical, said: "Ortho continues to be a growing and profitable business. In fact, Ortho forecasts another record year in sales and profits, following its 1991 record year. Chevron management values this business and its contribution to the corporation and will JANUARY 18,1993 C&EN
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