Science for our
Nation's
Energy Future

Energy Frontier Research Center

Community Website
Frontiers in
Energy Research
Newsletter
April 2014

Greening Paints, Plastics, and Fabrics

Scientists synthesize valuable chemical from biomass, not petroleum

Tyler Josephson

Scientists created the popular chemical  phthalic anhydride from biomass-derived sugars (Scheme 1).

The reaction can lead to side products, but by combining methanesulfonic acid with acetic anhydride (Scheme 2), fewer byproducts are produced and an 80% yield is achieved.

Over 3 million tons of phthalic anhydride are produced annually for the manufacture of plasticizers, unsaturated polyesters, and alkyd resins for use in plastics, fabrics, and paints. Unfortunately, this chemical is almost exclusively produced from petroleum, the consumption of which is associated with well-known environmental and political drawbacks. Producing aromatic compounds renewably from biomass is challenging, but researchers at the Catalysis Center for Energy Innovation (CCEI) have overcome several hurdles in the production of phthalic anhydride from biomass.

Two compounds produced from biorenewable sugars, furan and maleic anhydride, can react to produce phthalic anhydride. The reaction occurs in two steps: a Diels-Alder reaction to form an intermediate, followed by a dehydration reaction (Scheme 1). When the Diels-Alder reaction occurs, energy is released, increasing the temperature of the reaction mixture. This can be dangerous, because reactions happen faster at higher temperatures, and heat-producing reactions can accelerate and run away if not carefully controlled. However, this system has a built-in safety mechanism: if the temperature gets too high, the backwards reaction to the reactants is favored, and the reaction slows down.

The intermediate (oxonorbornene), in turn, forms phthalic anhydride at high temperatures and acidic conditions. However, competing reactions make a polymer that contaminates the products and reduces yield. The same reactor environment that promotes dehydration also promotes the formation of side products. To work around this challenge, the researchers at CCEI developed a molecular dehydration that does the job of a traditional acid without promoting polymerization. By combining methanesulfonic acid with acetic anhydride (Scheme 2), a mixed-sulfonic carboxylic anhydride is produced. By just using methanesulfonic acid, the yield to the products is only 11% because of undesirable side products. By using the carefully engineering mixed-sulfonic carboxylic anhydride, 80% yield was achieved.

Another attractive feature of the first reaction is that no solvent is used. Without the need for a solvent, energy and cost can be saved by reducing downstream separation costs and eliminating the need to clean up and recycle a solvent stream—making this “green” reaction even greener. By engineering new routes to renewable chemicals, we are getting closer to a more sustainable world.

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 Science, Office of Basic Energy Sciences. This material is also based upon work supported by the National Science Foundation (NSF) Graduate Research Fellowship. Mass spectral data was acquired at the University of Delaware on instruments obtained with the assistance of NSF.

More Information

Mahmoud, E, DA Watson, and RF Lobo. 2014. "Renewable Production of Phthalic Anhydride from Biomass-Derived Furan and Maleic Anhydride." Green Chemistry 16:167-175. DOI: 10.1039/C3GC41655K

About the author(s):

It's Easier to Be Green

Scientists synthesize valuable chemical from biomass, not petroleum

Every year, 3 million tons of phthalic anhydride, used in plastics, fabrics, and paints, is manufactured from nonrenewable petroleum. Using plants instead of petroleum demands an efficient and safe process. Scientists designed such a reaction that uses furan and maleic anhydride, both derived from biomass-based sugars, to form an intermediate molecule. This solvent-free reaction, which happens at room temperature, can "run away," but the team built in controls to reverse the reaction if it accelerates too quickly. A new catalyst breaks the intermediate and produces large volumes of phthalic anhydride, yielding 80% of the possible amount. Synthesizing chemicals from bio-sources would ease U.S. economic, environmental, and security issues. Scientists at the Catalysis Center for Energy Innovation, led by the University of Delaware, performed the study.

More Information

Mahmoud, E, DA Watson, and RF Lobo. 2014. "Renewable Production of Phthalic Anhydride from Biomass-Derived Furan and Maleic Anhydride." Green Chemistry 16:167-175. DOI: 10.1039/C3GC41655K

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.