Ethanol as a fuel additive – often touted as a domestic solution to curbing oil imports – has been suggested by some researchers to be an expensive answer to an ongoing problem. Corn, diverted from the food supply, is ethanol's usual raw material here in the United States. Creating ethanol through fermentation is slow and inefficient. Acid catalyzed processes generate significant waste byproducts.
But a method using the rare metal rhodium as a catalyst could make ethanol production cheaper, generate less waste, and use non-food biomass such as switchgrass – rather than corn kernels – as the source material. The key is gaining a greater understanding of how rhodium can do the job at maximum efficiency, and that involves studying interactions at the atomic level between the catalyst metal and promoter elements like manganese or vanadium.
Two University of Illinois at Chicago researchers hope their use of a sophisticated new electron microscope will lead to new chemical production models that expand the potential of ethanol and other alcohol-based fuel additives. Robert Klie, associate professor of physics, and Randall Meyer, associate professor of chemical engineering, received a $300,000 grant from the National Science Foundation to create models that explain what happens when individual atoms and atom clusters of these elements combine in certain ways and under various temperature conditions.
"The precise roles, the unique atomic structures that form at the surface are largely unknown. We don't know why they work," said Meyer. "We won't know until we identify the structures."
Klie will study the structure using an aberration-corrected scanning transmission electron microscope, scheduled to begin operating at UIC later this month. The first university-based instrument of its kind in the world, the microscope will let researchers view individual atoms with unparalleled resolution.
"Using electron microscopy as a starting point, we want to figure out where this promoter element atom sits on the catalyst," said Klie. "What does it do to the surface structure or the properties of the metal cluster? We'll use that in calculations to model the effects and understand the influence of this promoter element on the catalytic properties, and then basically come up with a prediction of why we think it works."
Klie and Meyer will then runs tests and refine their model to determine how the catalyst and promoter elements combine for the most efficient production of ethanol.
"Until recently we couldn't see individual atoms in the electron microscope. We really had no idea what the structure looked like," said Klie. "But with our new instrument, we can identify the position of the atoms, identify the different element species, and do this under different environments -- meaning higher or lower temperatures -- to see how atom positions change as we simulate reaction conditions."
Meyer said the researchers are interested mainly in the science and methodology going on, which may lead to ways of more efficiently producing alternative fuels and fuel additives, such as ethanol.
"If we can make ethanol in a targeted manner, then hopefully the lessons we learn from that will let us make Butanol (butyl alcohol) or some other higher hydrocarbon oxygenate in a targeted manner," said Meyer.
"The challenge is to try and do selective synthesis of a particular molecule through promotion and try to understand it."
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