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New lignin-solvent process harvests biofuel, paper and chemicals from plant material


August 2, 2012

Researchers have developed a new lignin-solvent process to separate cellulosic biomass into usable components (from left: lignin, hemicellulose, and cellulose)

Researchers have developed a new lignin-solvent process to separate cellulosic biomass into usable components (from left: lignin, hemicellulose, and cellulose)

In order to improve the sustainability credentials of biofuels, experts have been trying to figure out ways to produce them from non-food sources, such as cellulose – the material that makes up the cell walls of plants. Now, researchers from the Wisconsin Institute for Sustainable Technology (WIST) at the University of Wisconsin-Stevens Point have patented a process that they say paves the way for the creation of biofuels from cellulosic plant material.

WIST’s first patent is for a process that makes biofuels and other products from such material, including agricultural left-overs such as corn stover, or plants grown specifically for fuel production, such as hardwood and softwood trees. The method they’ve patented involves an aqueous solvent that separates cellulosic material into pure cellulose and lignin, the substance that gives woody biomass its rigidity. The lignin-solvent mixture can then be separated from the water and becomes a high-energy-density fuel that can be used independently or in combination with biodiesel.

But it’s not just cellulosic ethanol that can come out of this process. Pure cellulose can be used to make paper or can be converted into fermentable sugars. Besides biofuels, the sugars can also be used to make other renewable chemicals for industry including isoprene. It's a material used to make rubber, plastics and pharmaceuticals, but which comes mostly from petroleum.

The patent is an improvement on traditional processes for separating lignin from cellulose employed by the paper industry, which make it more difficult to convert the cellulose to sugars. Also, the lignin that's produced contains chemicals that cannot be easily or economically separated. The new lignin-solvent process results in a purified lignin and pure cellulose, which can be readily used to produce other renewable chemicals. This saves the lignin from being burned, which is the process conventional paper plants typically adopt to recover inorganic chemicals from the pulping process and to produce energy as well.

WIST is working with UW’s WiSys Technology Foundation to license the intellectual property to private industry for development. The researchers envisage several applications for the lignin, including carbon fiber.

Besides the lignin-solvent process, WIST hopes to develop a biorefinery that could be fitted to existing paper mills or to revive idle ones. They have performed the process in the lab and now are looking to develop it into a demonstration-scale plant.

Source: WIST

About the Author
Antonio Pasolini Brazilian-Italian Antonio Pasolini graduated in journalism in Brazil before heading out to London for an MA in film and television studies. He fell in love with the city and spent 13 years there as a film reviewer before settling back in Brazil. Antonio's passion for green issues - and the outdoors - eventually got the best of him and since 2007 he's been writing about alternative energy, sustainability and new technology. All articles by Antonio Pasolini

If this industrializes well it will open entirely new species of trees to commercial logging and make chopping down little trees less cost effective reducing the drive to clear cutting.


Wonder how the process would work with hemp?

Robin Lendrum

Lignin is presently separated from cellulose in huge amounts in every MDF factory using just water/steam and a refiner (counter rotating steel discs) giving pure cellulose and a lignin emulsion in water without the use of any solvents. The lignin is then usually separated by reverse osmosis membranes and used as fuel.


re; bahbah

The process is also energy intensive the solvent saves a lot of energy, and thus a lot of pollution is not generated.


Hemp would be fantastic with this process! We would get Oil from pressing the seeds and flour, Fiber for cloth getting rid of wasteful cotton that use the most water fertilizers and pesticides of all crops and only produces one thing weak fiber. Hemp would now produce a second stream of fuel ready material. Amazing!

Joseph Mertens

I can see switchgrass being harvested to feed this process. Countries like Brazil could use their leftover sugar cane stalks as a separate income stream.

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