Taming the Tasmanian Devil of Polymers: lignin, the orneriest, roughest, toughest, most un-cooperative and abundant natural polymer ever

July 11, 2018 | Jim Lane

In Florida this month, Ligno Tech Florida has started up a 100,000 metric tons per year lignin production plant at Fernandina Beach. The €95 million ($110 million) plant can be expanded by 50,000 metric tons. Borregaard has a 55% stake and Rayonier Advanced materials owns the rest. It’s proof positive that lignin is at last on the march, commercially speaking.

It’s been a long journey for lignin, the second most abundant natural polymer in the world, as Kapil Lokare observed in Depolymerizing lignin and making it pay – now, soon, never?, here. On average, trees are 15 – 30 % lignin by weight and 40% by energy.

He described it as an ugly, unwieldy molecule, and noted that in the world of process engineering “the general verdict across the board was to go after the low hanging fruit i.e. cellulose and hemicellulose but when it came to lignin the general consensus was, ‘You can do anything with it, except make money.’ In most operations, lignin is most often relegated to low-value uses such as providing process heat through combustion, or sold as a natural component of animal feeds in wet or dry corn mills.” But as Lokare observed, “times are changing. Lignin has developed into a sustainable and very satisfactory alternative to fossil fuels.

But applications have been needed. Firstly, applications that work, then applications that pay, then applications at scale. Let’s see how that work has been coming along.

Applications that work

Nylon, plastics, chemicals. This month we reported that researchers at the University of Portsmouth have developed a new, “promiscuous” enzyme that can convert plant waste into fuel, nylon, plastics and chemicals.

The cytochrome P450 enzyme—which is called promiscuous because it will work on a wide range of molecules—breaks down lignin, one of the main components of plants but a notoriously difficult material to convert. “To protect their sugar-containing cellulose, plants have evolved a fascinatingly complicated material called lignin that only a small selection of fungi and bacteria can tackle,” says Professor McGeehan of the University of Portsmouth. “However, lignin represents a vast potential source of sustainable chemicals, so if we can find a way to extract and use those building blocks, we can create great things.”

The study was published in Nature Communications.

Nylon, plastics, muconic acid, pyrogallol. In May, we reported that researchers at Sandia National Laboratories have engineered E. coli to convert lignin into precursors for products such as nylon, plastics, and pharmaceuticals.

Seema Singh and her team engineered genes known as lignin degraders into E. coli. While abundant, lignin has been difficult for science to use because it is the material that gives plant cell walls its strength. Singh’s team was able to lower the cost of the process by placing engineering the E. coli to be induced by lignin-derived compounds such as vanillin. Traditionally, bio refineries have had to buy high-cost inducers, lowering the viability of lignin-based processes. The solution was to “circumvent the need for an expensive inducer by engineering the E coli so that lignin-derived compounds such as vanillin serve as both the substrate and the inducer,” Singh said. And last November we reported that Sandia National Laboratories-led team had debuted a multi-stage process that begins by pre-treating lignin with a weak solution of hydrogen peroxide and water. Intermediary molecules vanillin and syringate result from the treatment.

A strain of E. coli specially modified by a Sandia microbiologist then consumes these middle-stage compounds, several additional compounds emerge in the mix, and ultimately the process results in muconic acid and pyrogallol.

Fuel cells. In May, we reported that researchers at Linköping University’s Laboratory of Organic Electronics have developed a lignin-based fuel cell that, unlike conventional fuel cells, does not emit carbon dioxide. Professor Xavier Crispin and his team used electrodes made from the conducting polymer PEDOT:PSS and benzendiols, aromatic compounds that can be extracted from lignin. The results have been published in the scientific journal Advanced Sustainable Systems.

3D printing filament. In April, we reported that the BC Innovation Council has awarded $300,000 to Darrel Fry of Advanced BioCarbon 3D and Jason Taylor of Selkirk College to develop biodegradable, 3D printing filament from engineering plastics and lignin-derived carbon fibers.The project was one of four winners of BC Innovation Council’s fourth Ignite Awards, which handed out just under $1 million to four BC research projects. Since the Ignite funding was launched in 2016, it has given out $3.5 million.

Meanwhile, a scalable processing technique developed by Oak Ridge National Laboratory uses plant-based materials for 3D printing and offers a promising additional revenue stream for biorefineries. Scientists created a new material with excellent printability and performance by tapping into lignin—a key component of plant cell walls that provides sturdiness. Lignin is a current byproduct of the biofuels process that could become a valuable coproduct with this new use. The method combines lignin, rubber, carbon fiber and acrylonitrile butadiene styrene, or ABS—commonly used in plastic toys—to 3D print structures with 100 percent improved weld strength between the layers over ABS alone. “To achieve this, we are building on our experience with lignin during the last five years,” said ORNL’s Amit Naskar. “We will continue fine tuning the material’s composition to make it even stronger.” The research team published details about the patent-pending process in Applied Materials Today.

Plastics, In February, we reported that Meridian Waste Solutions, Inc. successfully completed its performance testing for lignin-based resins produced by their patent-pending lignin polymer process. The product is a flowable resin extender that has shown outstanding mechanical properties and processing characteristics for the plastics market. At 15-25% inclusion rates, the product retains 100% of the tensile modulus, 100% of the impact strength, and over 90% of the tensile modulus in composites using polypropylene and polyethylene – a $265 billion market. Moving on a rapid development curve, the company’s offering meets a host of applications, including automotive components, agricultural products, building and construction and other durable goods.

Carbon fiber. Last May, we reported that waste material from the paper and pulp industry soon could be made into anything from tennis rackets to cars. “We have overcome one of the industry’s most challenging issues by discovering how to make good quality carbon fiber from waste,” said Dr. Joshua Yuan, Texas A&M AgriLife Research scientist and associate professor of plant pathology and microbiology in College Station. The research was published recently in Green Chemistry, the peer-reviewed journal of the Royal Society of Chemistry. Yuan’s research team has had several successes in making fuel and bioproducts from lignin. But even the biofuel making process leaves a large stockpile of waste. That led them to consider the possibility of making carbon fiber material. Yuan envisions a multi-stream integrated biorefinery in which lignin is separated in one location so that a variety of materials — the high density carbon fibers and the low density bioplastics, along with biofuels from plant feedstock like grasses — could be made at one facility.

Applications that pay

Phenolics. In February, we reported that Stora Enso launched a new biobased lignin, called Lineo, as a renewable replacement for oil-based phenolic materials which are used in resins for plywood, oriented strand board (OSB), laminated veneer lumber (LVL), paper lamination and insulation material. Stora Enso has been producing lignin at industrial scale since 2015 and is the largest kraft lignin producer in the world. Stora Enso is already selling Lineo to replace phenol, and the company is also looking at many other applications for this versatile material. A stable, free-flowing brown powder, Stora Enso’s lignin is separated during the kraft pulping process of Nordic softwood. Lineo has a high dry content, superior dispersibility and long storage time. With a higher reactivity and purity, Lineo is consistent from batch to batch and Stora Enso can supply different levels of dryness, according to customer demand.

Process solvents. In June, we reported that a closed-loop biorefinery could dramatically lower the cost of biofuels and related products. In this approach, the refinery produces the solvents it needs, rather than “importing” them. Scientists at the Joint BioEnergy Institute are developing a closed-loop biorefinery concept that uses waste lignin as a potential process solvent. How? They synthesized a new and renewable class of deep eutectic solvents. These solvents work well. When mixed with other liquids and used for biomass pretreatment, these solvents released sugar from grassy feedstocks for fuel and chemical production.

Applications at scale

Lignin production. In May, we reported that Sweetwater Energy and Europe’s largest wood pellet producer, the Tallinn, Estonia-based AS Graanul Invest, said that they will build a commercial-scale integrated biorefinery that will produce clean cellulosic sugars and highly pure lignin from 50,000 tons of local hardwood each year. In addition, the plant will allow the two companies to work with corporate partners to create and optimize innovative new products from sugar and lignin. The fully funded plant is made possible through significant investment and collaboration between the two companies by utilizing Sweetwater’s patented technology and Graanul’s existing infrastructure as one of the largest producers of wood pellets in the world.

Drop-in renewable diesel and gasoline. Also in May, we reported that Preem and RenFuel are assessing, in collaboration with Rottneros, the construction of the world’s first lignin plant for biofuels, at the pulp mill in Vallvik, Söderhamn. The plant is expected to produce an annual volume of 25,000-30,000 tons of lignin, and will be completed in 2021. The collaboration between the companies means that Preem will be the first fuel manufacturer in Sweden to use lignin in its production. Via the company Lignolproduktion AB, which is jointly owned by Preem and RenFuel, the aim is to reach a total annual production capacity of 300,000-500,000 tons of lignin, based on the assumption that more plants similar to that in Vallvik are established in the future. “Lignin can be refined to create both renewable diesel and renewable petrol, and used in all vehicles. Lignin, like tall oil, will help us phase out fossil fuels to an even greater extent. It is a valuable raw material in our renewable fuel efforts, and is based on by-products from the Swedish forestry industry. It is also available in large volumes,” says Petter Holland, Managing Director of Preem.