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September 2011

Drawing a Biomass Catalytic Roadmap

Researchers discover the catalytic routes to produce renewable fuels from biomass

Matthew Mettler

Catalyst researchers can determine the relative preference of chemical reactions that convert biomass molecules to biofuels. The figure shows the relative energy of molecules present in the conversion of biomass, where lines higher up in the figure represent less stable intermediates and lower lines represent more stable compounds. This figure shows that by using a Ni/Pt(111) catalyst rather than Pt(111), a more favorable and lower energy path can be found to produce biofuels.

The catalytic chemistry of biomass has for decades been a black box from which biofuels and chemicals emerge. Now, researchers from the Catalysis Center for Energy Innovation have developed a combined experimental and computational method that can determine the fundamental reaction steps involved in producing biofuels. This research is the first step toward designing custom catalysts for biofuel production.

Complexity of the problem: Thousands of chemical routes could be taken to convert biomass, such as switchgrass, to industrially relevant products.Determining the dominant pathway, or set of reactions that convert a starting material to product, is similar to looking at a U.S. highway map and trying to determine the best route between Boston and Los Angeles. On such a trip, road construction, refueling breaks, and other delays must be accurately predicted to determine the best route.

An analogous problem arises in catalytic conversion of biomass. Biomass molecules react faster when a metal catalyst is present. Furthermore, these molecules follow different pathways on the metal surface, and the route taken depends on reaction conditions such as the type of metal catalyst employed. Because biomass molecules have so many different atoms and bond types, the number of ways a molecule can break down or re-form on the surface is very large, implying that there are many potential routes for converting biomass.

Revealing biomass pathways: The researchers created a global map for the biomass conversion reactions. They determined the likelihood of each reaction on a particular catalytic surface. These parameters were input into the global map, and the updated map was used to determine the energetically preferred conversion route for the catalyst.

Once a reaction map was constructed for a particular catalyst, the scientists re-computed reaction parameters for a different catalyst and determined how the new catalyst affects the conversion process. For the catalysts examined, the team showed that adding a small amount of nickel to a platinum catalyst drastically speeds up important reactions. By reducing the resistance for specific reactions, they showed that the overall biomass conversion rate can be substantially increased.

“This is a significant breakthrough in the reaction engineering of biomass catalysts which will allow us to understand the fundamental reactions of biomass molecules on metal catalyst surfaces,” says Wei Fan, a biomass conversion researcher on the team who works at the University of Massachusetts.

More Information

Salciccioli M, W Yu, MA Barteau, JG Chen, and DG Vlachos. 2011. “Differentiation of O-H and C-H Bond Scission and Mechanisms of Ethylene Glycol on Pt and Ni/Pt using Theory and Isotopic Labeling Experiments.” Journal of the American Chemical Society 133(20), 7996-8004.DOI:10.1021/ja201801t.

Acknowledgments

This work was supported as part of the Catalysis Center for Energy Innovation, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Basic Energy Sciences.

About the author(s):

  • Matthew Mettler is a Ph.D. candidate at the University of Delaware and is a student in the Catalysis Center for Energy Innovation. He is advised by Dion Vlachos and formerly worked for the DuPont Company.

A GPS for Biofuels?

New method shows main routes taken in turning plants to fuels

Using a new method to determine the main reaction in converting biomass to fuels, researchers found that adding a pinch of nickel to a platinum catalyst greatly reduces (red line) the amount of energy needed.

Too many options. When turning agricultural waste, wood waste or specific crops into fuels, the main problem is just that — too many options. Each process has a feedstock, a desired product and a catalyst, which is typically a metal that drives the reaction. The process can involve a multitude of reactions. Some are efficient. Others are slow and wasteful. For scientists, biofuels production is like looking at a U.S. highway map and trying to determine the fastest, safest, most fuel-efficient route between Boston and Los Angeles. There are hundreds of combinations of highways and back roads, and the optimal route is not obvious. Also, road construction and weather delays can play a part in picking the best route. To pick the best route for a biofuels conversion, researchers built a global map. The map shows the major routes and considers “delays” and “driving conditions.” With the map for a reaction and a catalyst in place, scientists can test various scenarios. In recent tests using the mapping method, scientists showed that adding a bit of nickel to a platinum catalyst drastically decreased the amount of energy needed to reach the destination. By reducing the resistance for specific reactions, they demonstrated the overall biomass conversion rate can be substantially increased. This approach opens the door for tailoring catalysts and reactions to move bio-based fuels into the mainstream. The Catalysis Center for Energy Innovation, led by the University of Delaware, conducted the work.

More Information

Salciccioli M, W Yu, MA Barteau, JG Chen, and DG Vlachos. 2011. “Differentiation of O-H and C-H Bond Scission and Mechanisms of Ethylene Glycol on Pt and Ni/Pt using Theory and Isotopic Labeling Experiments.” Journal of the American Chemical Society 133(20), 7996-8004.DOI:10.1021/ja201801t.

Disclaimer: The opinions in this newsletter are those of the individual authors and do not represent the views or position of the Department of Energy.