|
|
|
|
|
||||
|
Most voyages of discovery begin with the unknown: a blank spot on the map, the faint outlines of craters on the moon or curiosity about the subatomic world. Most discoveries, particularly scientific ones, start with a question: Can we reach the moon? Can we map the genes in the human body? Can we circumnavigate the globe? "When we began thinking about a new direction for our research," says Peter Stair, Northwestern professor of chemistry, "we asked ourselves, what's the hardest problem, something basic, that would have a lot of benefit if we could solve it?" If Stair and his colleagues reach their goal, they'll find new ways to clean up pollution and conserve energy, and they'll make exciting discoveries in catalysis, which in layperson's terms is the chemical reaction created by a catalyst. A $7.9 million, five-year grant, funded by the National Science Foundation and the U.S. Department of Energy and awarded in 1998, has led to the establishment of the Institute for Environmental Catalysis at Northwestern, with Stair as director. To support the IEC's research, the state of Illinois and the University will add another $4.8 million in cost-sharing. The questions being raised include some that are elemental. "Catalysts change one material into another without being changed themselves. How do they do it?" wonders the wry, gray-haired Stair. He's brimming over with enthusiasm as he glances at the monitor of his computer. "We don't know if we'll be successful in finding out, but we've got the resources to try."
Mighty Catalysis Now retired, Haensel earned his doctorate in chemistry while working as a research chemist for Chicago-based Universal Oil Products Co. (called UOP LLC these days and now headquartered in Des Plaines, Ill.). He was assigned to Northwestern's Vladimir N. Ipatieff Laboratory, the precursor of today's Center for Catalysis and Surface Science, which in turn spawned the IEC. Haensel worked alongside such giants in the field as Ipatieff and Herman Pines. "There were always surprises in the old days," Haensel says. "Many new reactions were discovered, such as alkylation and isomerization." From plastics to perfumes, nylons to Oreos, breakthroughs were made in catalysis that we now take for granted. Chemists' discoveries squeezed extra energy out of dwindling oil reserves and raised the octane of auto and aviation fuel. The emerging plastics industry, which sprang from this research, produced melamine plates and Tupperware containers, beach balls and Naugahyde. But there was a downside: Energy consumption rose, and air and water pollution increased. Industry was forced to look for ways to reduce the impact of human activities on the environment, and research on catalysis led to "greener" products. Alkyd paint replaced its oil-based predecessor. Catalytic converters and unleaded gas reduced the polluting impact of cars.
Complexity in the Environment Building on the Catalysis Center's long tradition of collaboration among chemists, chemical engineers and materials scientists, the Institute for Environmental Catalysis adds a new dimension -- biology and the tools biologists bring to exploration. "We're sailing under a whole new banner," says Kimberly Gray, the IEC's associate director. "When I began working with the folks at the Catalysis Center, I stressed that you can't do work in the environmental field without biology. They'd always wanted to get more involved with biological systems, and they found it interesting." Gray, who came to Northwestern in 1995, is an environmental engineer. "This is the reason I came here -- to do interdisciplinary work of this sort," she says. "It's the most intellectually stimulating science I've ever done." The IEC has assembled an impressive team of 21 professors, 25 graduate students and a half-dozen postdoctoral research fellows. They've teamed up with two national labs, Pacific Northwest National Laboratory in Richland, Wash., and Argonne National Laboratory southwest of Chicago, and recruited chemists in industry to advise the research effort (see story on page 20). Indeed, managing the scientific explorations of so many collaborators is a daunting task. Each discipline has its own vocabulary, acronyms, tools and techniques, and researchers don't always grasp the details, or even the "big picture," of what their colleagues are up to. "The problems the team is investigating -- and the system we're using to investigate them -- are at a level of complexity beyond what the individual scientist can deal with," says Stair. "We need the tools and expertise from everyone - materials scientists, chemists, chemical engineers and environmental engineers."
The Big Beam "It's called a synchrotron storage ring," says Michael Bedzyk, associate professor of materials science and engineering, "because it produces synchrotron radiation ‹ electromagnetic radiation in frequencies that range from the infrared band to X-rays." Bedzyk and other researchers on the catalysis team use several of the APS's 60 experimental stations to observe chemical processes that take place on a surface. "We're looking at them on the atomic or molecular scale," Bedzyk says. "Our goal is to study catalytic processes in real time." X-rays produced by the synchrotron are 1 angstrom (100 millionth of a centimeter) in wavelength. "You can resolve the distance between atoms," says Bedzyk, "which are typically separated by angstroms." Having the tools to examine atomic structure may unlock some of the secrets of what happens when catalysts work their magic.
Catalysis Chemistry — A Mystery Imagine the surface of a catalyst as the flat bottom of a Hershey's chocolate bar with almonds. The almonds represent the special clusters where the "action" occurs. The IEC researchers want to know the shape and distribution of the catalytic clusters ‹ and how they affect reactions. Catalysts work by bumping around electrons. Some chemicals gain electrons (called reduction); others lose electrons (oxidation). But the best catalyst is "selective": It directs electrons to and from exactly the right locations. Selectivity improves manufacturing because catalysts will convert raw materials to desirable products; undesirable byproducts, which today end up as pollutants, will decrease.
Big Gains for the Environment "The problem with contaminants derived from industry is that microorganisms can't easily attack their chemical structure," says Bruce Rittmann, John Evans Professor of Environmental Engineering. "Kim Gray's research is tremendously exciting as a pretreatment to 'soften up' those chemical structures." In Gray's research, a powdered semiconductor catalyst, irradiated by a laser beam, converts harmful chemicals so they can be easily biodegraded by enzyme catalysts in microorganisms. Gray calls the process "photobiocatalysis." If successful on a larger scale, this technology will aid in cleaning up the military's stockpiles of munitions waste, such as TNT, and chlorinated compounds, such as the toxic fungicides used to pressure-treat lumber. Chemicals that once ended up in Superfund sites will be easier to biodegrade, and industry will be able to treat waste before it reaches the groundwater. On another project, Jean-François Gaillard, a biogeochemist in the departments of civil engineering and geological sciences, is characterizing the types of manganese oxide formed by bacteria found in lakes. The microorganisms create versatile catalysts that convert heavy metals, which are harmful to wildlife and humans, to less hazardous forms. "We want structural information about manganese oxides," says Gaillard, who has cryogenically frozen his samples of bacteria and X-rayed them at Argonne's APS. "Manganese oxides are a potential catalytic surface for transforming heavy metals, such as cobalt." Harold Kung, professor of chemical engineering, who often collaborates with his wife, Mayfair Kung, research associate professor of chemical engineering, is studying the basic chemistry of catalysis and its applications to several processes that can bring about better environmental quality and improve energy efficiency. Applications include improved fuel processing for fuel cells and more energy-efficient expoxide production. Kung is also doing research on a catalytic converter that works well with lean-burning internal combustion engines -- engines that have high fuel efficiency. "The current efforts by the transportation industry to improve fuel economy are hampered by unacceptable levels of pollutant emissions," says Kung. "But if you could overcome that, you could put lean-burning engines on cars and trucks. We asked ourselves what would be the necessary chemical properties of a catalyst that would remove nitrogen oxide from engine exhausts." It's the back-and-forth -- asking practical questions and urgently desiring to understand the chemistry -- that will lead to major contributions from these researchers. And these are but a few examples of the many projects under way. In the next five years, the team should be closer to its goal of comprehending the behavior of catalysts in the environment and in finding better ways to make "green" products, manufacture environmentally friendly chemicals and reduce pollution. "The Center for Catalysis and Surface Science at Northwestern has a long and distinguished history of research, but the newly funded Institute for Environmental Catalysis gives this research a whole new focus," says Lydia Villa-Komaroff, Northwestern vice president for research. "They have a chance to do some exciting science and solve significant environmental problems."
Marylee MacDonald is a freelance writer based in Evanston.
|
