To many consumers, the ubiquitous plastic beverage bottle is an environmental zero. It's made of nonrenewable fossil resources, holds a low-value product, is used only once, and often ends up in a landfill or, worse, as litter fouling our land and oceans. But plastic packaging remains a fact of life. Chemical and material companies, and their big-brand customers, hope to turn this zero into a hero by making plastic resins from renewable ingredients rather than petroleum.
Most of today's plastic beverage bottles are made of polyethylene terephthalate (PET). In 2016, over 13 million metric tons of PET were used for beverage bottles, according to chemical consultancy PCI Wood Mackenzie. Given PET's dominance and increasingly poor reputation, it's not surprising that brand companies such as Coca-Cola and Danone are interested in new approaches to packaging their products. PET manufacturers have taken small steps toward making the polymer out of sugar or other renewable raw materials. But DuPont, Corbion, and Synvina—a joint venture of BASF and Avantium—are taking a different tack. For them, using sugar is an opportunity to improve the performance of today's plastic packaging. They are piloting new supply chains based on the sugar-derived furan ring.
Compared with PET, furan polymers like polyethylene furanoate (PEF) offer improved gas barrier properties. They can preserve a soda's fizz longer by keeping oxygen out and CO2 in. According to Corbion, that can as much as double shelf life. Since avoiding food waste is the biggest argument in favor of plastic packaging, increasing the ability to preserve food would add to plastic's green street cred. The catch, though, is that PEF and other furan plastics face the same hurdles as biobased PET, and then some. Commercializing both resin types requires massively scaling up a new raw material supply chain and reducing costs to compete with traditional plastics. Moreover, PEF is not a drop-in replacement for PET. To capture the full value of furan performance, bottles and other packaging will need to be redesigned.
"While I think the world needs new polymers that can be sustainable and have superior performance and properties, at some point they will have to be competitive," says James Iademarco, president of Strategic Avalanche, a consulting firm for industrial biotechnology strategy and innovation. He expects any inroads made by PEF in beverage bottles will be slow to come because materials firms are also working on biobased PET, which, unlike PEF, is a direct replacement for petroleum-based plastics.
Most PET is synthesized by reacting the petrochemicals ethylene glycol and terephthalic acid. A few firms are making ethylene glycol that's derived from sugar-fermented ethanol rather than fossil fuels. Coca-Cola has created the 30% biobased PlantBottle by harnessing this source of ethylene glycol. Firms pursuing furan polymers use biobased 2,5-furandicarboxylic acid (FDCA) in place of terephthalic acid in the polyester's backbone. Reacting FDCA with sugar-derived ethylene glycol can yield a 100% biobased plastic.
Coca-Cola and other beverage giants are keeping their options open for getting to 100% by backing firms developing terephthalic acid made from biobased aromatics as well as those pursuing furanic chemistry. Two firms, Avantium and Origin Materials, are working on both types of biobased resin. Though they share the same general recipe, Synvina, Corbion, and DuPont have mapped out diverging pathways to furanic polymers. Synvina uses two catalytic steps to produce FDCA from fructose using Avantium's YXY process. It dehydrates the sugar to produce the furanic intermediate methoxymethylfurfural and then oxidizes to FDCA.
Chemical structures for the intermediates methoxymethylfurfural, hydroxymethylfurfural, the monomer 2,5-furandicarboxylic acid and the polymer polyethylene furanoate are shown. Synvina's chief executive officer, Patrick Schiffers, points out that neither FDCA nor PEF have ever been produced at commercial scale. What's more, the joint venture is "constructing a completely new chemical value chain based on renewable feedstock."
But Schiffers has great confidence in the catalytic process, in part because Avantium has operated an FDCA pilot plant in the Netherlands since 2011. "Synvina holds the right expertise for this by combining the technology leadership of Avantium and the engineering and production excellence of BASF," Schiffers claims. He says the companies have produced high-quality PEF bottles using the pilot plant's FDCA and provided samples to partners.
Synvina will use what it has learned at the pilot plant at its next site, a 50,000-metric-ton-per-year plant the firm is calling a reference facility because it hopes to license the technology to other manufacturers. In contrast, Corbion, true to its roots as a fermentation powerhouse, is pursuing a biocatalytic route to FDCA. It uses a different intermediate than Synvina does, hydroxymethylfurfural (HMF), that's also made by sugar dehydration. Corbion's microbes take over from there, consuming HMF and spitting out FDCA.
According to Stephen Roest, Corbion's market development manager for biobased innovations, the microbes are efficient and highly selective eaters of HMF, leading to high-purity FDCA. However, as is true in most microbial reactions, the product has to be extracted from a fermentation broth.
Like Synvina's Schiffers, Roest is confident in Corbion's ability to scale up FDCA production. The firm has biobased intermediates experience from its Succinity succinic acid venture with BASF. It is also building a large-scale polylactic acid plant in Thailand with joint-venture partner Total. Efficiency is the focus at DuPont and the reason the company has chosen furan dicarboxylic methyl ester (FDME), a derivative of FDCA, as its monomer. As do its competitors, DuPont starts with fructose dehydration, but it doesn't need to purify the mix of intermediates that results. Instead, the firm oxidizes the mixture to make FDME, which can be polymerized into polytrimethylene furandicarboxylate, a polymer similar to PEF. DuPont developed the process in partnership with the agriculture giant ADM.
DuPont is constructing a 60-metric-ton-per-year pilot plant to help develop markets for the monomer; the facility will be complete by the end of the year. And the company says it has spare polymerization capacity. Already, DuPont is hearing from brand owners who "are very excited about a new performance monomer," says Michael Saltzberg, DuPont's global business director of biomaterials. In the meantime, DuPont will work on developing markets using lessons it learned while commercializing another biobased monomer, 1,3-propanediol (PDO). "Having good partners makes a big difference. For PDO we worked with our manufacturing partner Tate & Lyle and with Mohawk Industries, our customer," he recalls. Mohawk weaves carpet from Sorona-brand fibers, which are made with PDO.
"We have to really make sure to understand the value we create all the way downstream. There has to be a value and a benefit for everyone," Saltzberg says. He acknowledges that it will be a few years before the company produces large quantities of FDME.
By weight, biobased furanic polymers cost two to four times as much as the petroleum-derived competition, Saltzberg reports. But aside from being completely biobased, they also stand out by beating PET on performance. Compared with PET, furanic polymers are up to 60% stronger and are better gas barriers, which means that packages can use much less plastic to provide the same level of protection.
"Everyone looks at price at the beginning, but the real question is the cost of the bottle, which can be lighter weight. Then you add in the marketing value of 100% biobased," Saltzberg says. DuPont's strategy is to find higher-value, smaller-scale packaging markets where those benefits are particularly desirable.
Corbion's Roest anticipates interest in using a thin layer of PEF to provide an additional gas barrier to PET packaging to improve shelf life. PEF can also be used on its own or in combination with PET for flexible packaging or films. Like PET, PEF can be stretched into a biaxially oriented packaging film that is a potential winner for wrapping cheese and meat. And unlike biobased polylactic acid films, which a few years ago made for a notoriously noisy bag for SunChips snacks, furanic resin films are quiet when handled.
Synvina has been working for five years to develop plastic bottles that extend the shelf life of oxygen-sensitive products such as juices, nectars, teas, and sauces. And while food packaging is Synvina's main focus, Schiffers points out that FDCA can be converted into polyamides for engineering plastics and fibers; polyurethanes for foams, coatings, and adhesives; and esters for personal care products and lubricants. Given their strong barrier properties, furanic polymers may be able to steal market share from glass and aluminum; one oft-noted example is beer bottles. But to conclusively win over eco-minded brands and consumers, manufacturers will have to show that furanic packages are better than competing materials over their life cycle—starting from the sugar raw materials to recycling and end of life.
In the U.S., DuPont's Saltzberg argues that corn-derived fructose is an appropriate and efficient feedstock for biopolymers. "The U.S. is the Saudi Arabia of corn," he says, noting that the country's production of corn ethanol is peaking and that demand for high-fructose corn syrup is falling. Plenty of corn sugar will be available to use in polymers.
In Europe, Synvina says it will begin with fructose derived from corn, wheat, or other crops. Environmental activists, however, frown on the use of food crops to make biofuels;it's not clear if that attitude will spread to other industrial uses of sugar. "In the longer term, we aim to use lignocellulosic biomass such as wood and wood residues, pulp, and agricultural by-products," Schiffers says.
One U.S. company, Origin Materials, hopes to make competitively priced FDCA from similar lignocellulosic feedstocks. Last month it acquired technology from Eastman Chemical for making FDCA from sugar. It also purchased an Eastman oxidation pilot plant. Origin is small compared with the likes of BASF and DuPont, but it raised $40 million earlier this year and has a partnership with Danone and Nestlé to develop biobased monomers for bottles.
Chemical companies and brands don't have much say over what happens to packaging after the consumer is done with it. In the U.S., only 30% of PET bottles are recycled, and less than one-quarter of domestic recycled PET is used to make new bottles, according to the National Association for PET Container Resources. And just as PEF is not a drop-in replacement for PET, it is also not a drop-in at the recycling plant.
The European PET Bottle Platform, an assessment organization, has given interim approval for Synvina's PEF to go to recyclers, with some restrictions. A stream of up to 2% of PEF bottles can be recycled with PET without resulting in a hazy appearance. Recyclers can also use near-infrared sorting technology to separate PEF bottles for recycling.
The companies investing in furanic materials are confident that the material's green claims will be a selling point. "It's a generational thing," Saltzberg says. "Just as consumers want to know about where their food comes from, and now how sustainable their textiles are and so on, the playing field for packaging tilts in our favor."
Paul Mitchell, director of technology licensing at Eastman, observes that the time is ripe for new packaging materials, a change compared with when the company first developed its FDCA process. "There is a resurgence in interest in biobased plastics, and a lot of the work we did is now at the center of enabling some of that."
But successful new polymers are rare, as Eastman knows. When the company launched the copolyester Tritan in 2007, Mitchell says, it had its own performance branding and high-visibility "alpha customers" that wanted to use it in their products. "Because of the brand involvement, we think there is a path to viability for FDCA, but there is still a way to go to develop at a scale that can be economically viable," Mitchell recounts.
Iademarco, the consultant, says it's wise to think long term, like five to 10 years from now, when evaluating the potential for furanic polymers. In that time, the potential savings from the materials' better performance will be clear, and recycling issues can be addressed.
For BASF, DuPont, and Corbion, getting in on the ground floor with a new resin could help them capture more of the expanding plastic packaging market. "If they can get a performance bump that is also renewable and sustainable," Iademarco says, "they will go after it."
Chemical & Engineering News
Copyright © 2017 American Chemical Society
By Melody M. Bomgardner