Every year, more than seven million barrels of oil are used in the production of propylene glycol (PG), an ingredient found in many common household items, including anti-freeze, plastics, cosmetics, and food additives. Until recently, the only economically viable source of feedstock for producing PG was petroleum.
But one American company, with the support of the U.S. Department of Energy (DOE) national labs, decided to find an alternative.
The Opportunity: Producing Plant-Based Propylene Glycol Cost-Effectively
In the mid-2000s, Archer Daniels Midland (ADM), a leading U.S. agricultural and food processing corporation, sought to expand its business into the development of both biofuels (such as ethanol) and biobased processing chemicals, including PG.
Biobased PG has the same chemical make-up as petroleum-derived PG, but is produced from renewable, low-carbon feedstocks, such as sugar alcohols from corn, sugar cane, soy or sunflowers. Biobased PG reduces the demand for oil, enhances energy security, and has a lower carbon dioxide impact than its petroleum-based alternative.
Scientists have long known how to create PG from alcohols and biomass, but the conversion process creates byproducts and water in addition to PG. Scientists did not know how to control the proportions of PG to water/byproduct, and the unpredictability, which often created more water than PG, made this process too expensive to use commercially.
ADM needed a partner with scientific expertise in converting biomass to help them develop a commercially viable process, and the company found that partner in Pacific Northwest National Laboratory (PNNL).
The Pathway: A Chance Discovery
PNNL, working with the National Corn Growers Association, was exploring ways that sorbitol, a corn-derived sugar alcohol typically used as a sugar substitute, could be used to create PG. Funded by DOE’s Bioenergy Technologies Office, the project succeeded. The team discovered a catalyst that efficiently made PG not only from sorbitol, but also from glycerol. Glycerol is another type of sugar alcohol, commonly made from soybeans, palm, or tallow. However, glycerol is also a byproduct of the production of biodiesel. With this new discovery, PNNL could theoretically take the glycerol produced from creating biodiesel and not only stop this from going to waste, but efficiently create PG.
PNNL reached out to ADM to explore scaling up the process of creating PG from glycerol for industrial purposes. PNNL brought the catalyst and its engineering expertise; ADM supplied industrial focus and production know-how for full-scale commercialization.
The Breakthrough: Bringing Together Lab and Industry Expertise for a Solution
It was critical to understand the industrial requirements to make PG production from glycerol commercially viable. ADM and PNNL worked together closely on this project, with ADM specifying the necessary ratio of PG to water and PNNL using its scientific expertise to refine the catalyst. Finally, they were able to produce the coveted ratio of one PG molecule to one water molecule.
Then, PNNL further improved the process by using ADM’s corn feedstock samples, which are closer to real-world feedstock than ones used previously in the lab. The improved catalyst significantly increased the amount of glycerol converted to PG—from 40%-60% previously, to almost 90%. The improved rates and yields substantially decreased the costs of production, making it economically viable to produce on a commercial scale.
The Impact: Extending the Economic and Environmental Benefits of Renewable Biomass
As a result of the collaborative research between PNNL and ADM, the company now has a full-scale production facility at its manufacturing plant in Decatur, Illinois. The facility employs 140 people and can produce 100,000 metric tons of PG from renewable sources per year. ADM uses or sells this biobased product for use in deicers, cosmetics, pet food and pharmaceuticals, among others.
This new source of PG allows ADM to produce an economically competitive PG from renewable sources that meets American Society for Testing and Materials standards for 100% biobased renewable carbon content. It also meets U.S. Department of Agriculture BioPreferred standards, a voluntary labeling initiative that certifies this PG as biobased.
The project has received numerous awards, including an R&D 100 award, an annual prize granted by R&D Magazine to recognize the most innovative technologies, in 2010, two Federal Laboratory Consortium for Technology Transfer awards, and an American Chemical Society Green Chemistry award in 2014.
Source: EERE, press release, 2018-01-09.