Novel Catalytic Methods for Green Chemistry: Industrial Chemicals from Renewable Sources
Fall 2014 - Written by Dow-Resnick Fellow Anton Toutov
The 21st century will see fundamental changes in chemical manufacturing worldwide. It is no longer sufficient for processes to simply be scalable, inexpensive, and high yielding, but rather they must also become as efficient and sustainable as possible. In particular, as the world’s oil reserves steadily diminish, there is now more than ever a desire to employ non-petroleum sources of carbon in chemical production. Moreover, new demanding legislation on greenhouse emissions, energy use, and production of waste streams provides additional challenges as well as opportunities for innovation in green chemistry.
Professor Brian Stoltz and Resnick Fellow Yiyang Liu have been engaged in the discovery of powerful sustainable methods for industrial chemical synthesis. Their contribution to this field involves the development of non-petroleum-based routes to linear alpha olefins (LAOs). This class of industrial chemicals is used in a variety of applications from the manufacture of plastics to the production of drilling fluids and lubricants; they are currently produced on nearly four million metric tonne scale annually. The current process is energy- and material-intensive and employs ethylene, a petroleum-derived feedstock, as input.
Liu has recently succeeded in making a crucial first step toward the sustainable chemical production of LAOs with a new discovery in green catalysis. His new method allows for the streamlined production of industrially important LAOs from renewable carbon sources. Palm oil-derived fatty acids were chosen as the non-petroleum based source of carbon for this process due to their considerable natural abundance, low cost, and of course their inherent renewability. Moreover, since fatty acids are naturally produced from CO2 by photosynthesis, the large-scale employment of this method would further serve to balance the concentration of atmospheric CO2. Liu is likewise investigating alternative fatty acid sources for this process.
Whereas prior strategies towards the sustainable production of LAOs were generally unsuccessful, requiring the use of high loadings of expensive catalysts and impractical reaction conditions, the method of Liu and Stoltz is efficient and cost-effective. The optimized process uses very low (i.e., 0.05 mol%) loadings of an inexpensive catalyst, and simple, industrially amenable reaction conditions. The use of solvent-free conditions is useful and convenient, minimizing solvent waste and facilitating reaction set up.
“This work is one step closer to achieving the goal of sustainable chemistry,” says Liu, “by switching from petroleum to biomass as the crude starting material. In the long run, the fatty acids will come from algae, a photosynthetic microorganism that can grow in seawater and therefore not compete for limited land and fresh water resources required for agriculture.”
Preliminary aspects of this work were published in 2013 in Advanced Synthesis and Catalysis. A more detailed treatment and further application of the method in fine chemical synthesis is currently in preparation for submission to Angewandte Chemie.