Acrylonitrile, a petroleum-derived commodity chemical, is one of the most widely used monomers in the chemical industry with many commercial applications. Today, acrylonitrile is used in the production of acrylic fibers for carpets, clothes, and fabrics, and in plastics such as food containers, and packaging materials.
Most importantly for this project, acrylonitrile is also the primary building block in carbon fiber composites, which are used for lightweighting applications in automotive and air transportation. Acrylonitrile is produced today industrially via an energy-intensive and chemically hazardous process.
Propylene price volatility and environmental sustainability have motivated a search for alternative pathways using bio-derived feedstocks such as glycerol and glutamic acid. Yet none have been able to compete with the traditional process in terms of cost and yield. Now, new NREL research is showing promise toward achieving this goal.
Newly published in Science, “Renewable Acrylonitrile Production” shows a path toward a cost-effective, bio-based acrylonitrile manufacturing process. Researchers were able to achieve a 98% yield of acrylonitrile using a new catalytic process. Based on yields alone, this is a very important discovery.
“The high acrylonitrile yield allows us to propose a potential industrial process for the conversion of lignocellulosic biomass to renewable acrylonitrile and carbon fibers,” said Gregg Beckham, group leader at NREL and senior author of the study. “Historically, acrylonitrile prices have been volatile due to ties to propylene prices. This alternative manufacturing process, one that relies on renewably sourced feedstocks, could help stabilize acrylonitrile prices and lead to broader market adoption of carbon fiber-based materials.”
The new process eliminates production of hydrogen cyanide—a toxic side product—uses a simpler and less expensive catalyst, and could be done in a simpler reactor configuration. Moreover, this new high-yield process can utilize non-food biomass, such as agricultural wastes, as a feedstock instead of propylene.
NREL estimates the new process could put the selling price of biomass-derived acrylonitrile below $1 per pound from cellulosic biomass or starch-based sugars. A $1 per pound target was deemed necessary for cost competitiveness with conventionally produced acrylonitrile.