Polyethylene terephthalate (PET) is one of the most common plastics and can be cascaded mechanically during its life cycle. However, recycling affects the mechanical properties of the material, and the virgin material is constantly in demand. If a worn material could be depolymerized to its chemical building blocks, then a virgin polymer could be generated from old fibers. In this work, we have developed a benign organo-catalytic depolymerization of PET to yield dimethyl terephthalate (DMT) and ethylene glycol (EG) without the need for purification of generated monomers. By recirculating the solvent and organo-catalyst, a solvent/substrate ratio of 3:1 was achieved. The depolymerization was successfully applied to other polyesters, polycarbonates, and polycotton. The cotton isolated from the polycotton depolymerization was successfully processed into viscose fibers with a tenacity in the range of nonwaste cotton-derived viscose filaments. The global warming potential (GWP) of PET depolymerization was evaluated by using life cycle assessment (LCA). The GWP of 1 kg PET recycling is 2.206 kg CO₂ equivalent, but the process produces DMT, EG, and heat, thereby avoiding the emissions equivalent to 4.075 kg CO₂ equivalent from the DMT, EG, and steam-energy production through conventional pathways. Thus, the net result potentially avoids the emission of 1.88 kg of CO₂ equivalent. The impact of this process is lower than that of waste PET incineration and conventional PET recycling technologies.

To achieve a viable forest-based biorefinery, both the carbohydrate and lignin parts of the raw material should be valorized. While lignin-first approaches have successfully been applied to hardwoods, where up to 50% of the lignin -close to the 'theoretical maximum yield'- has been transformed to valuable monophenols; limited studies have targeted softwoods. Softwood lignin comprises lower amount of beta-ether bonds and this results in lower theoretical and observed yields of monophenols in reductive catalytic fractionation (RCF): below 5 wt% yield of initial biomass has been reported. In this study, we use beetle infected spruce, a softwood, as raw material. A fast fractionation was developed to give a pulp and a lignin fraction in the absence of transition metal catalysts. The carbohydrate matrix was valorized to dissolving grade pulp in 37 wt% from biomass (86% yield), and suc-cessfully spun to Lyocell fibers. The lignin fraction was dissolved in furfural -operating as green 'solubility-enhancing-agent'- to blend lignin in inert carrier liquids to promote controlled hydrotreatment to yield biofuels in 10 wt% (60% carbon yield) from initial biomass. Life cycle assessment (LCA) of the value-chain showed improved sustainability in several footprint categories compared to cotton production. Thus, upgrading of a considered forestry waste to high value textile fibers and biofuels has been achieved: in case of lignin beyond the 'theoretical maximum yield'. This is an important step to mitigate a future growing demand of textiles without negatively affecting irrigation or land use.

To make biorefining more environmentally sustainable, preferably residues from forestry should be used and more than one fraction should be upgraded. A third of raw materials from forestry & horbar;tops and branches (T & B)― are either left in the forests or collected and incinerated to a low value. Herein, we apply a fast fractionation to valorize two of the fractions of this forestry residue. The cellulose is converted to textile fibers and all the lignin to hydrocarbons. The environmental sustainability of the novel value chain was studied by life cycle assessment (LCA), and benefits were found in four out of five impact categories. These are important steps to increase fiber production without affecting environmental impact, making biorefining competitive.

Thermosetting polymeric materials have advantageous properties and are therefore used in numerous applications. In this study, it was hypothesized and ultimately shown that thermosets could be derived from comparably sustainable sub-components. A two-step procedure to produce a thermoset comprising of Kraft lignin (KL) and the cross-linker adipic acid (AdA) was developed. The cross-linking was activated by means of an acetylating agent comprising isopropenyl acetate (IPA) to form a cross-linking mixture (CLM). The cross-linking was confirmed by FTIR and solid-state NMR spectroscopy, and the esterification reactions were further studied using model compounds. When the KL lignin was mixed with the CLM, partial esterification occurred to yield a homogeneous viscous liquid that could easily be poured into a mold, as the first step in the procedure. Without any additions, the mold was heated and the material transformed into a thermoset by reaction of the two carboxylic acid-derivatives of AdA and KL in the second step.

Here, we show that lignin-first biorefining of poplar can enable the production of dissolving cellulose pulp that can produce regenerated cellulose, which could substitute cotton. These results in turn indicate that agricultural land dedicated to cotton could be reclaimed for food production by extending poplar plantations to produce textile fibers. Based on climate-adapted poplar clones capable of growth on marginal lands in the Nordic region, we estimate an environmentally sustainable annual biomass production of ∼11 tonnes/ha. At scale, lignin-first biorefining of this poplar could annually generate 2.4 tonnes/ha of dissolving pulp for textiles and 1.1 m³ biofuels. Life cycle assessment indicates that, relative to cotton production, this approach could substantially reduce water consumption and identifies certain areas for further improvement. Overall, this work highlights a new value chain to reduce the environmental footprint of textiles, chemicals, and biofuels while enabling land reclamation and water savings from cotton back to food production.

Organosolv pulping performed in a high-pressure Soxhlet extractor using carbon dioxide as a mild and recyclable acid is described. The system reached a liquid to wood ratio of 6.6 yielding 43 wt% of dissolving grade quality pulp from Populus trichocarpa. The set-up enabled to run reductive catalytic fractionation to yield a lipophilic lignin oil without affecting the performance nor the purity of the final pulp.