Page 1 of 2
About 85 percent of the nation’s energy needs are met by the combustion of fossil fuels such as oil, natural gas, and coal – finite resources that make the United States dependent upon other countries while polluting the environment through carbon emissions. In order to achieve energy security in an environmentally friendly manner, the nation’s energy strategy must include alternative technologies based on renewable sources such as biofuels, solar, wind, and nuclear power. A central challenge, however, is the development of new processes and materials capable of tapping these sources and feeding the country’s vast energy needs. A key part of the solution involves catalysis, the process of speeding up and directing chemical reactions.
In the effort to develop new, environmentally friendly, and renewable energy technologies, liquid fuels such as gasoline, diesel, and ethanol will continue to serve an important role. Liquid fuels are unmatched in their capability to store energy at high density, and they provide a very effective and economical way to transport and store energy over long distances for long periods of time, for example, as gasoline in a car. But most alternative energy sources do not directly create chemical fuels. Instead, a series of chemical conversions must first take place, assisted by various catalytic processes.
Many of the currently used catalytic processes, developed during the past century, were intended for the conversion of fossil fuel products. The next-generation catalytic challenges require complex steps to develop alternative liquid fuels, e.g. by directly converting carbon dioxide into useable fuel sources with the assistance of power from the sun. To meet these technical and theoretical challenges, researchers at Brookhaven National Laboratory are developing an atomic-level understanding of these chemical transformations and the catalysts that enable them.
In contrast to burning fossil fuels such as oil and natural gas, the use of hydrogen molecules as a fuel produces significantly lower pollution. In addition, hydrogen atoms – a constituent of water – are widely abundant. However, finding simple, inexpensive ways to produce hydrogen fuel from water, and to store and efficiently use it, is technologically tricky.
Brookhaven scientists are developing catalysts to support a hydrogen-based economy. Many of these studies involve catalysts that assist in hydrogen production for fuel cells, which combine hydrogen and oxygen without combustion to produce direct electrical power and water.
To find some of the world’s best catalysts, look no further than your backyard, where Mother Nature has perfected sustainable and clean energy production. For this reason, Brookhaven Lab researchers are trying to design catalysts inspired by photosynthesis, the natural process by which green plants convert sunlight, water, and carbon dioxide into oxygen and carbohydrates. The goal is to design a bio-inspired system that can produce fuels like methanol, methane, and hydrogen directly from water and carbon dioxide using renewable solar energy.
For example, Brookhaven researchers have mimicked a step in photosynthesis called “water oxidation catalysis,” one part of water splitting, a high-energy process that separates water into hydrogen and oxygen. Specifically, the scientists tested how a novel ruthenium complex catalyzes water oxidation to form oxygen. Finding efficient and inexpensive catalysts to assist in this reaction is crucial to making the process useful for hydrogen production for fuel cells.
While the major challenges to establishing a hydrogen economy are being worked out, scientists also are investigating the production and use of renewable liquid fuels such as methanol, ethanol, and butanol produced from carbon dioxide.
Methanol, for example, may be used as a fuel in an easily adaptable internal combustion engine that exists today or in fuel cell-powered cars in the future.
Brookhaven researchers are investigating catalysts that can efficiently and selectively produce these desired liquid fuels from renewable energy and starting materials such as water and carbon dioxide, or from the conversion of biomass.
Brookhaven researchers also are working on projects that bridge basic and applied science. A good example of this work is the development of new fuel cell electrocatalysts, which convert hydrogen to electricity for use in electric vehicles.
Although platinum is the most efficient electrocatalyst for accelerating the oxygen reduction reaction in fuel cells, it is expensive, and not stable enough to be used during stop-and-go driving. Brookhaven scientists developed the first platinum monolayer fuel cell electrocatalyst, which has long-term stability and the same activity as the traditional model but 10 times less platinum, making it much more cost-effective. Researchers are now studying several types of this monolayer catalyst in the laboratory and are working with several companies to test its performance in actual fuel cells.
In addition, this research is advancing the development of electrocatalysts that allow the direct use of liquid fuels in fuel cells, taking away the need for the internal combustion engine. Research on electrocatalysts also could lead to the development of other applications, including methanol fuel cells, which could be used to power portable electronics such as computers and cell phones.
When fossil fuels are burned, sulfur impurities within the fuels become sulfur dioxide, a major air pollutant and a source for the formation of acid rain. Industry uses metal-oxide catalysts in catalytic converters and smokestack scrubbers to help keep sulfur pollutants out of the atmosphere.
But there’s a new emphasis on making this process more efficient and less expensive. Brookhaven scientists have worked with industry to help develop new catalysts that destroy sulfur dioxide more effectively, yet present no health or environmental hazards and are inexpensive.
A highlight of the Brookhaven catalysis effort is Radoslav Adzic and his research group’s work on nanostructured electro-catalysts, like the gold/platinum/copper catalyst shown here. More...
Synthesis techniques have been developed to place platinum atoms on the surface of nanoparticles to produce new catalysts that have higher stability, use less platinum, and are more resistant to impurities for hydrogen fuel cells. The new catalysts made at Brookhaven already meet the future targets the Department of Energy has set for fuel cell catalyst performance.
Last Modified: November 6, 2009