Critical elements—and especially rare earths—were in the news in 2011, as a sample of headlines demonstrates:
Widespread concern over the future availability of critical elements led the Chemical Sciences Roundtable to hold a workshop on September 29-30, 2011, in Washington, D.C., on the role of the chemical sciences in finding alternatives to critical resources. Key topics addressed during the workshop included
“The chemical sciences have not yet been much involved in the national discussion over critical elements,” said Patricia Thiel, Division Director for Science and Technology at Ames Laboratory, Distinguished Professor of Chemistry at Iowa State University, and one of three members of the organizing committee for the workshop. Yet historically the chemical sciences have played an essential role in this area. In the early years of the 20th century, fertilizer was so scarce that it was sometimes stolen, and war broke out in South America over one of the world’s two main sources of nitrogen, guano from bird droppings (the other main source at the time was sodium nitrate mined in Chile). Then, in 1909, Fritz Haber discovered a way to fix atmospheric nitrogen as ammonia using iron as a catalyst at high pressure, and a few years later Carl Bosch, an industrial chemist at BASF, developed a way to apply this process on an industrial scale. The Haber-Bosch process was born in controversy, since it prolonged Germany’s ability to wage World War I without blockaded imports from South America. But the discovery has had “great impact that continues to reverberate today,” said Thiel. Most significantly, by facilitating intensive agriculture, it enabled the great and continued expansion of the human population in the 20th and 21st centuries.
The same year that Fritz Haber fixed nitrogen using the precursor to the modern process, chemists produced the first totally synthetic rubber. When the price of natural rubber, which was produced primarily in Asia, increased sharply in 1925, industrial production of synthetic rubber rose substantially. “But the real stimulant to industrial production came in World War II,” said Thiel, “when the Axis countries took over the supply fields in Asia and cut off all supplies of natural rubber to the Allies.”
In modern times, critical materials are used in many everyday activities. Essentially all electronic devices use a wide variety of these materials, including rare earth elements,
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1 Introduction and Overview Critical elements—and especially rare earths—were in “The chemical sciences have not yet been much involved in the news in 2011, as a sample of headlines demonstrates: the national discussion over critical elements,” said Patricia Thiel, Division Director for Science and Technology at • “Stable rare earth supply sought,” Daily Yomiuri Ames Laboratory, Distinguished Professor of Chemistry Online, September 8. at Iowa State University, and one of three members of the • “Chasing rare earths, foreign companies expand in organizing committee for the workshop. Yet historically the China,” New York Times, August 24. chemical sciences have played an essential role in this area. • “China to reform rare earth exports after WTO,” In the early years of the 20th century, fertilizer was so scarce Reuters, July 6. that it was sometimes stolen, and war broke out in South • “China holds the world hostage in rare earth metals,” America over one of the world’s two main sources of nitro- Business Insider, June 13. gen, guano from bird droppings (the other main source at • “Got Yttrium?” Time, March 28. the time was sodium nitrate mined in Chile). Then, in 1909, • “Can Toyota innovate its way out of the Prius’s rare Fritz Haber discovered a way to fix atmospheric nitrogen earth element problem?” Christian Science Monitor, as ammonia using iron as a catalyst at high pressure, and a January 19.1 few years later Carl Bosch, an industrial chemist at BASF, developed a way to apply this process on an industrial scale. Widespread concern over the future availability of critical The Haber-Bosch process was born in controversy, since it elements led the Chemical Sciences Roundtable to hold a prolonged Germany’s ability to wage World War I without workshop on September 29-30, 2011, in Washington, D.C., blockaded imports from South America. But the discovery on the role of the chemical sciences in finding alternatives to has had “great impact that continues to reverberate today,” critical resources. Key topics addressed during the workshop said Thiel. Most significantly, by facilitating intensive agri- included culture, it enabled the great and continued expansion of the human population in the 20th and 21st centuries. • The economic and political matrix for addressing the The same year that Fritz Haber fixed nitrogen using the issue, precursor to the modern process, chemists produced the first • The history of societal responses to key mineral and totally synthetic rubber. When the price of natural rubber, material shortages, which was produced primarily in Asia, increased sharply • The applications for and properties of existing minerals in 1925, industrial production of synthetic rubber rose sub- and materials, and stantially. “But the real stimulant to industrial production • The chemistry of possible replacements. came in World War II,” said Thiel, “when the Axis countries took over the supply fields in Asia and cut off all supplies of natural rubber to the Allies.” In modern times, critical materials are used in many 1Roderick Eggert, one of the three members of the workshop organizing everyday activities. Essentially all electronic devices use a committee, listed these headlines in his presentation summarized in wide variety of these materials, including rare earth elements, Chapter 2. 1
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2 THE ROLE OF THE CHEMICAL SCIENCES IN FINDING ALTERNATIVES TO CRITICAL RESOURCES precious metals, and other rare, expensive elements of the platinum-group metals, as catalysts in industry. Various periodic table. For example, the Toyota Prius uses at least aspects of the catalysis process are more economically eight different critical elements in its design. As described in significant than the cost of the metals, and many chemical Chapter 2, in everything from the hybrid electric motor, to the processes have evolved from originally using low-cost metals LCD screen in the passenger compartment, to the recharge- such as cobalt to much scarcer metals because the high cost able NiMH battery to power the car, to the catalytic converter of separations and capital expenses overwhelm the difference that cleans the exhaust, critical elements play a primary role in the price of the metal. Opportunities exist for further work in the operation of this modern car. in the areas of emissions catalysis, hydrosilylation, hydro- Those examples “nicely illustrate the role of chemistry in formylation, and enantioselective catalysis to help address addressing shortages of critical materials,” Thiel concluded, this cost differential. “and the chemical sciences continue to have an enormous Jingguang Chen, Claire D. LeClaire Professor of Chemi- role to play today.” cal Engineering and Co-Director of the Energy Frontier Research Center, University of Delaware, presented his research results aimed at reducing and replacing platinum OVERVIEW OF THE WORKSHOP in catalysis. In water electrolysis, for example, monolayer After Thiel’s introductory remarks, the workshop con- platinum can achieve the same activity as bulk platinum sisted of five pairs of related presentations and subsequent using vastly less precious material. In biomass conversion discussions. These presentations are summarized briefly reactions, a nickel on tungsten carbide catalyst can replace below and in Chapters 2-6 of this summary. a platinum nickel catalyst for the production of hydrogen. These platinum-free catalysts also are very active in the direct conversion of cellulose from plants to useful chemicals Chapter 2: Assessments of Criticality that can be used in our current chemical plan infrastructure. Roderick Eggert, Professor and Director of the Divi- sion of Economics and Business at the Colorado School Chapter 4: Replacing Critical Materials with Abundant of Mines, presented a framework for assessing the avail- Materials ability of critical elements that was developed by a National Research Council committee that recently examined the Morris Bullock, Laboratory Fellow and Director of issue (NRC, 2008). Elements can be positioned in a two- the Center for Molecular Electrocatalysis at the Pacific dimensional array comparing their importance in use and Northwest National Laboratory, described the development supply risk. Using this framework, the most critical elements of electrocatalysts based on inexpensive, Earth-abundant are the platinum-group elements, the rare earths, manganese, metals. Low-temperature fuel cells generally use platinum, indium, and niobium. Eggert elaborated on his view that but nickel complexes can effectively catalyze the oxida- the chemical sciences are essential in finding substitutes for tion of hydrogen. Related complexes of cobalt, iron, and critical elements, enhancing mineral extraction and recovery manganese are being studied as well, showing that it is processes, improving manufacturing efficiency, and enabling possible to rationally design catalysts based on abundant, better recycling. inexpensive metals as alternatives to the more expensive Diana Bauer, Director of the Office of Economic Analysis precious metals. in the Department of Energy’s Office of Policy and Inter- Christine Lambert, Technical Leader, Ford Research and national Affairs, presented the main findings of the Critical Advanced Engineering, recounted the 30-year history of Material Strategy released by the Department of Energy using base metals to replace precious metals in three-way (DOE) in 2010. The report found that “four clean energy automobile catalysts that simultaneously control hydrocar- technologies—wind turbines, electric vehicles, photovoltaic bons, carbon monoxide, and nitrogen emissions in gasoline cells, and fluorescent lighting—use materials that are at vehicle exhaust. There is no known combination of base risk of supply disruptions in the short term. In the report, metals that are as active and durable as precious metals. But five rare earth elements (dysprosium, neodymium, terbium, there has been a general reduction of precious metals use europium, and yttrium), as well as indium, were assessed as due to the addition of stabilizers to improve catalyst effec- most critical in the short term” (DOE, 2010). tiveness over longer mileages, reduction of poisons present in the fuel and oil, and tighter control of engine parameters. Current diesel aftertreatment technologies, which do not use Chapter 3: Critical Materials in Catalysis precious metals, also have been undergoing rapid evolution James Stevens, Corporate Fellow, Core Research and with the development of catalysts that have improved thermal Development Department, Dow Chemical Company, gave a stability and wider operating windows for temperatures and broad perspective on the use of critical materials, especially flow rates.
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3 INTRODUCTION AND OVERVIEW Chapter 5: Optoelectronics and Photovoltaics Chapter 6: Critical Materials in Large-Scale Battery Applications Joseph Shinar, Senior Physicist at the Ames Labora- tory, Professor and Chair of the Department of Physics David Bradwell, Chief Technology Officer at Liquid and Astronomy, and Professor of Electrical and Computer Metal Battery Corporation and Visiting Scientist at the Engineering at Iowa State University, discussed five critical M assachusetts Institute of Technology, explained that materials or families of materials in optoelectronic tech- batteries designed for grid-scale energy storage applications nologies: erbium-doped fiber amplifiers, which are critical face a unique set of material selection challenges. Whereas components of the repeaters in optical fiber networks; solid- many other power technologies can improve performance via state lasers based on lanthanide dopants in yttrium aluminum enhanced material microstructure or device design optimiza- garnet, which are used extensively in spectroscopy and laser tion, the energy capacity of a battery is directly related to the lithotripsy; indium in various ubiquitous III-V devices; amount of active material. For broad-scale energy-intensive transparent conducting indium tin oxide films, which are applications, this means the active materials must be inher- currently behind virtually 100 percent of all displays and ently low cost and sufficiently abundant. Interestingly, figure similarly in the emerging organic light-emitting diode the cost of the raw active materials is not always the primary (OLED)-based solid-state lighting paradigm; and heavy cost driver; thus, to more fully evaluate the opportunity for rare earth elements which are currently critical for efficient emerging storage technologies, the entire system must be OLED-based displays. He described examples highlighting considered. A host of new battery technologies—including the importance, availability, and estimated amounts of these a set of liquid metal battery projects—are being pursued at metals that will be needed as these technologies mature and universities, startup companies, and large well-established pervade the world economy in the coming decades. corporations across the country. Ken Zweibel, Director of the George Washington Univer- Jay Whitacre, Chief Technology Officer of Aquion and sity Solar Institute, discussed the rapidly dropping cost and Professor of Engineering and Public Policy at Carnegie increasing use of photovoltaic (PV) solar cells and prospects Mellon University, looked at battery technologies for energy for further expansion of these materials. The most impor- applications, including lithium-ion and aqueous electrolyte tant materials that are needed to produce solar power today batteries. The adoption of lithium-ion battery technology is, include silicon, silver, tellurium, and cadmium. Emerging as of this workshop, not constrained by materials. Rather, technologies could require significant quantities of indium, it is constrained by the way the materials function and the selenium, molybdenum, gallium, germanium, arsenic, and complexity of the device itself. In contrast, low-cost, low- ruthenium. Some of these materials have supply or cost energy-density, and long-lifetime batteries could serve as a issues, which has spurred interest in developing strategies feasible and economic means of energy storage. to reduce the amounts of materials needed to effectively produce electricity. New sources and additional refining Chapter 7: General Observations capacity will be essential if demand for these materials greatly increases. The final chapter compiles some general observations made by the individual workshop speakers that apply broadly to critical materials and the role of the chemical sciences in addressing these issues.
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