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UNique Refinery Approach to Valorise European Lignocellulosics

Periodic Reporting for period 3 - UNRAVEL (UNique Refinery Approach to Valorise European Lignocellulosics)

Período documentado: 2021-06-01 hasta 2022-05-31

The EU has formulated a vision of a competitive, innovative and sustainable Europe leading the transition towards a post-petroleum society. The UNRAVEL project aims to minimise the dependency on fossil resources by development and scale-up of biomass valorisation processes to contribute to the transition towards a more bio-based economy.

The overall UNRAVEL objective was to develop advanced pre-treatment, separation and conversion technologies for complex lignocellulosic biomass to high-value products (chemicals and construction products). The pre-treatment technologies comprise mild pre-extraction of the feedstock and the FABIOLA™ (FractionAtion of lignocellulosic BIOmass using Low temperature aqueous Acetone) fractionation process to unravel lignocellulosic biomass into cellulose, lignin and hemi-cellulose. Innovative downstream processing includes an energy efficient lignin precipitation technology and novel enzyme technologies for lignin depolymerisation and hydrolysis of the cellulose pulp. The isolated fractions are subsequently converted into building blocks for chemicals (xylonic acid, malic acid, acetone) and construction products (PUR/PIR insulation foam and bitumen additive for roofing materials). All process steps were scaled up from lab (TRL 3) to pilot (TRL 5) and the resulting product applications were demonstrated at industrially relevant scale. An extensive techno-economic and sustainability assessment was performed to assess the viability of the process.
Feedstocks from forestry, agriculture, municipal waste and food-processing residues were analysed for their composition. Development of optimum pre-extraction conditions and subsequent valorization of fine chemicals was conducted. Biomass pre-extraction was successful at both the lab- and pilot-scale and produced a cleaner feedstock, enriched in lignocellulose.

Lab-scale fractionation was validated at pilot scale, showing excellent translation from lab-scale operation. Additionally, lignin was isolated in high yield and purity at TRL5 using a continuous falling film lignin precipitation process (LigniSep). The obtained lignin was converted to smaller lignin fragments using MetninTM technology. The sugars were fermented to obtain xylonic acid and acetone in high yields.

Lignin-based polyols with properties matching the requirements for PUR/PIR foam production were successfully produced by a new protocol that uses ethylene carbonate. This protocol has the advantage to be safer and easier to scale-up than the common protocol using oxypropylation. Lignin-based polyol replacement was successful at 20% substitution and the PUR foams complied with the industrial specifications.

The use of lignin to replace the SBS polymer for waterproofing membranes showed to be not a good alternative as the performance was limited compared to the industrial specifications, also after methylation. Lignin modification to increase hydrophobic moieties may better resemble the hydrophobic SBS polymer and provide more promising results.

The enzymatic conversion of glucose to fructose from UNRAVEL hydrolysates was performed to demonstrate an additional valorisation route. The glucose conversion was successful and expands the offering of the UNRAVEL biorefinery and strengthen its business case for potential investments.

The economic assessment concluded that the UNRAVEL concept has shown favorable prospects. The assessed scenarios indicate that a green premium of 15-40% would be needed for an attractive business-case and that potential further process intensification and integration could lower the green premium.

The sustainability assessment revealed the environmental burden of biorefinery processing can be reduced by introducing several successful innovations:
1. A new approach to pre-extraction of biomass to make underutilised residues available for lignocellulosic biorefineries
2. An improvement of the yield/quality of compounds obtained in the core fractionation process
3. Lignin modification with ethylene carbonate for use as a polyol in PUR/PIR insulation foams

Several project dissemination activities, networking events, press releases, policy briefs, fact sheets and online presence activities were held to build up the project visibility at the local, national and international level and to show how outcomes are relevant to the public. The project resulted in six peer-reviewed publications, one policy brief and two fact sheets.
UNRAVEL has developed an innovative lignocellulosic value chain based on the FABIOLATM fractionation and subsequent processing of the biopolymers to high value products, and scaled these technologies up from TRL3 to 5. A complete techno-economic and a sustainability assessment was performed.

The FABIOLATM process was upscaled to TRL 5 for complex biomass residues and mixtures thereof, e.g. birch with bark and branches, wheat straw and a mix of those. Fractionation of mixed feedstocks proved feasible with similar yields/quality compared to individual feedstocks, but synergies are to be expected from improved logistics rather than improved fractionation characteristics. The continuous lignin precipitation process obtained a lignin and solvent recovery of 95% and 99%, respectively. Mass and energy balances for the process at industrial-scale indicated that the heat use of Fabiola fractionation is 52% lower than the reference ethanol organosolv process (target was 30%).

Valorization of biomass residues is positively contributing to the overall sustainability and viability of a biorefinery process. The biomass pre-extraction step prior to fractionation showed that this is opens possibilities for processing complex and mixed lignocellulosic biomass residues. Benefits include a reduced need for acid as catalyst, a reduced lignin content of the pulps, an increase in hemicellulose sugar yield and a higher lignin purity.

Novel enzymes with high efficiency in alkaline conditions were applied with dissolved lignin. This technology enables more economical and sustainable lignin valorisation towards bio-based products, e.g. PUR/PIR insulation foam and bio-based bitumen for roofing applications.

UNRAVEL proved that efficient sugar fermentation to chemicals is feasible, especially from the cellulose derived C6 sugars. Purification of the hemicellulose hydrolysate using activated carbon is recommended in most cases for efficient fermentation.

The integrated assessment indicated that the UNRAVEL processes do not lead to unacceptable social risks but recommends to pay attention not to cause such risks when deploying the technology at larger scale. Biorefineries according to the UNRAVEL concept can contribute to the creation of jobs and prospering local economies, mostly in less privileged rural areas and by a local procurement approach.

Biomass residues can feed several large-scale biorefineries if a careful site selection process is followed. Straw is still available in sufficient amounts and roadside grass is largely unused but available in only rather small quantities. Another recommendation was to target more sustainable use options for the C5 and C6 sugars.

The key messages have been further translated into usable knowledge for policy makers (as Policy Brief) and wider audiences (via news and social media posts). Results were also integrated in an updated version of the Exploitation Roadmap for the use and scale-up of project results after its end.
Overview of the UNRAVEL cascading biorefinery