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1. Production of renewable alcohols from maple wood using supercritical methanol hydrodeoxygenation in a semi-continuous flowthrough reactor

   https://doi.org/10.1039/d0gc03218b  

   Galebach, Peter H.; Soeherman, Jimmy K.; Gilcher, Elise; Wittrig, Ashley M.; Johnson, Jillian; Fredriksen, Thomas; Wang, Chengrong; Lanci, Michael P.; Dumesic, James A.; Huber, George W. (December 2020, Green Chemistry)

   null (Ed.)

   Biomass conversion to alcohols using supercritical methanol depolymerization and hydrodeoxygenation (SCM-DHO) with CuMgAl mixed metal oxide is a promising process for biofuel production. We demonstrate how maple wood can be converted at high weight loadings and product concentrations in a batch and a semi-continuous reactor to a mixture of C 2 –C 10 linear and cyclic alcohols. Maple wood was solubilized semi-continuously in supercritical methanol and then converted to a mixture of C 2 –C 9 alcohols and aromatics over a packed bed of CuMgAlO x catalyst. Up to 95 wt% of maple wood can be solubilized in the methanol by using four temperature holds at 190, 230, 300, and 330 °C. Lignin was solubilized at 190 and 230 °C to a mixture of monomers, dimers, and trimers while hemicellulose and cellulose solubilized at 300 and 330 °C to a mixture of oligomeric sugars and liquefaction products. The hemicellulose, cellulose, and lignin were converted to C 2 –C 10 alcohol fuel precursors over a packed bed of CuMgAlO x catalyst with 70–80% carbon yield of the entire maple wood. The methanol reforming activity of the catalyst decreased by 25% over four beds of biomass, which corresponds to 5 turnovers for the catalyst, but was regenerable after calcination and reduction. In batch reactions, maple wood was converted at 10 wt% in methanol with 93% carbon yield to liquid products. The product concentration can be increased to 20 wt% by partially replacing the methanol with liquid products. The yield of alcohols in the semi-continuous reactor was approximately 30% lower than in batch reactions likely due to degradation of lignin and cellulose during solubilization. These results show that solubilization of whole biomass can be separated from catalytic conversion of the intermediates while still achieving a high yield of products. However, close contact of the catalyst and the biomass during solubilization is critical to achieve the highest yields and concentration of products. 

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2. Specificity of Thermal Destruction of Nonwoven Mixture Systems Based on Bast and Viscose Fibers

   https://doi.org/10.3390/polym17091223  

   Kalauova, Altynay S; Palchikova, Ekaterina E; Makarov, Igor S; Shandryuk, Georgiy A; Abilkhairov, Amangeldi I; Kalimanova, Danagul Zh; Naukenov, Meirbek Zh; Shambilova, Gulbarshin K; Novikov, Egor M; Song, Junlong; et al (May 2025, Polymers)

   The research investigates the thermal behavior of mixed systems based on natural and artificial cellulose fibers used as precursors for carbon nonwoven materials. Flax and hemp fibers were employed as natural components; they were first chemically treated to remove impurities and enriched with alpha-cellulose. The structure, chemical composition, and mechanical properties of both natural and viscose fibers were studied. It was shown that fiber properties depend on the fiber production process history; natural fibers are characterized by a high content of impurities and exhibit high strength characteristics, whereas viscose fibers have greater deformation properties. The thermal behavior of blended compositions was investigated using TGA and DSC methods across a wide range of component ratios. Carbon yield values at 1000 °C were found to be lower for blended systems containing 10–40% by weight of bast fibers, with carbon yield increasing as the quantity of natural fibers increased. Thus, the composition of the cellulose composite affects carbon yield and thermal processes in the system. Using the Kissinger method, data were obtained on the value of the activation energy of thermal decomposition for various cellulose and composite systems. It was found that natural fiber systems have three-times higher activation energy than viscose fiber systems, indicating their greater thermal stability. Blends of natural and artificial fibers combine the benefits of both precursors, enabling the deliberate regulation of thermal behavior and carbon material yield. This approach opens up prospects for the creation of functional carbon materials used in various high-tech areas, including thermal insulation. 

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3. Engineered Sorghum Bagasse Enables a Sustainable Biorefinery with p ‐Hydroxybenzoic Acid‐Based Deep Eutectic Solvent

   https://doi.org/10.1002/cssc.202101492  

   Wang, Yunxuan; Meng, Xianzhi; Tian, Yang; Kim, Kwang_Ho; Jia, Linjing; Pu, Yunqiao; Leem, Gyu; Kumar, Deepak; Eudes, Aymerick; Ragauskas, Arthur_J; et al (October 2021, ChemSusChem)

   Abstract Integrating multidisciplinary research in plant genetic engineering and renewable deep eutectic solvents (DESs) can facilitate a sustainable and economic biorefinery. Herein, we leveraged a plant genetic engineering approach to specifically incorporate C₆C₁monomers into the lignin structure. By expressing the bacterialubiCgene in sorghum,p‐hydroxybenzoic acid (PB)‐rich lignin was incorporated into the plant cell wall while this monomer was completely absent in the lignin of the wild‐type (WT) biomass. A DES was synthesized with choline chloride (ChCl) and PB and applied to the pretreatment of the PB‐rich mutant biomass for a sustainable biorefinery. The release of fermentable sugars was significantly enhanced (∼190 % increase) compared to untreated biomass by the DES pretreatment. In particular, the glucose released from the pretreated mutant biomass was up to 12 % higher than that from the pretreated WT biomass. Lignin was effectively removed from the biomass with the preservation of more than half of the β‐Ο‐4 linkages without condensed aromatic structures. Hydrogenolysis of the fractionated lignin was conducted to demonstrate the potential of phenolic compound production. In addition, a simple hydrothermal treatment could selectively extract PB from the same engineered lignin, showing a possible circular biorefinery. These results suggest that the combination of PB‐based DES and engineered PB‐rich biomass is a promising strategy to achieve a sustainable closed‐loop biorefinery. 

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4. Hierarchically Structured Composite Fibers for Real Nanoscale Manipulation of Carbon Nanotubes

   https://doi.org/10.1002/adfm.202009311  

   Xu, Weiheng; Ravichandran, Dharneedar; Jambhulkar, Sayli; Zhu, Yuxiang; Song, Kenan (January 2021, Advanced Functional Materials)

   Abstract Carbon nanotube (CNT)‐reinforced polymer fibers have broad applications in electrical, thermal, optical, and smart applications. The key for mechanically robust fibers is the precise microstructural control of these CNTs, including their location, dispersion, and orientation. A new methodology is presented here that combines dry‐jet‐wet spinning and forced assembly for scalable fabrication of fiber composites, consisting of alternating layers of polyacrylonitrile (PAN) and CNT/PAN. The thickness of each layer is controlled during the multiplication process, with resolutions down to the nanometer scale. The introduction of alternating layers facilitates the quality of CNT dispersion due to nanoscale confinement, and at the same time, enhances their orientation due to shear stress generated at each layer interface. In a demonstration example, with 0.5 wt% CNTs loading and the inclusion of 170 nm thick layers, a composite fiber shows a significant mechanical enhancement, namely, a 46.4% increase in modulus and a 39.5% increase in strength compared to a pure PAN fiber. Beyond mechanical reinforcement, the presented fabrication method is expected to have enormous potential for scalable fabrication of polymer nanocomposites with complex structural features for versatile applications. 

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5. Effect of the spin‐line temperature profile on the mechanical properties of melt electrospun polyethylene fibers

   https://doi.org/10.1002/app.50668  

   Shabani, Elnaz; Gorga, Russell E. (March 2021, Journal of Applied Polymer Science)

   Abstract The covid‐19 pandemic has revealed the need for alternative production approaches with low startup costs like electrospinning for filter needs, the most imperative element of the personal protective equipment (PPE). Current attempts in advancing melt electrospinning deal with developing strategies for fiber diameter attenuation toward sub‐micron scale. Here, the attunement in the spinning‐zone temperature known as ''spin‐line temperature profile'' was utilized as a baseline for fiber diameter reduction. The mechanical performance of the melt‐electrospun linear low‐density polyethylene (LLDPE) fibers is reported to characterize their structural transformation with respect to various spin‐line temperature profiles. With an increase in the spin‐line temperature to above 100°C in the area of cone formation, an increased tensile and yield strength along with fiber diameter reduction by four‐folds was demonstrated. A significant increase in toughness, by almost three times, without compromising the stiffness and Young's modulus was observed. The dynamic mechanical analysis revealed that spinning in high temperatures produces changes in the alpha (α) relaxation, contributing to the significant increase in strain at break. These results are significant because polyolefin fibers are an imperative element of medical textiles and PPE. Therefore, developing a correlation for process‐structure‐properties for emerging production techniques like melt electrospinning becomes critical. 

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