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1.
Efficient conversion of lignin to aromatic hydrocarbons via depolymerization and subsequent hydrodeoxygenation is important. Previously, we found that NbOx species played a key role in the activation and cleavage of C–O bonds in lignin and its model compounds. In this study, commercial niobic acid (HY-340), niobium phosphate (NbPO-CBMM) and lab-made layered niobium oxide (Nb2O5-Layer) were chosen as supports to study the effect of Brönsted and Lewis acids on the activation of C–O bonds in lignin conversion. A variety of Ru-loaded, Nb-based catalysts with different Ru particle sizes were prepared and applied to the conversion of p-cresol. The results show that all the Ru/Nb-based catalysts produce high mole yields of C7–C9 hydrocarbons (82.3–99.1%). What's more, Ru/Nb2O5-Layer affords the best mole yield of C7–C9 hydrocarbons and selectivity for C7–C9 aromatic hydrocarbons, of up to 99.1% and 88.0%, respectively. Moreover, it was found that Lewis acid sites play important roles in the depolymerization of enzymatic lignin into phenolic monomers and the cleavage of the C–O bond of phenols. Additionally, the electronic state and particle size of Ru are significant factors which influence the selectivity for aromatic hydrocarbons. A partial positive charge on the metallic Ru surface and a smaller Ru particle size are beneficial in improving the selectivity for aromatic hydrocarbons. 相似文献
2.
Michael Zirbes Dr. Tobias Graßl Rieke Neuber Prof. Dr. Siegfried R. Waldvogel 《Angewandte Chemie (International ed. in English)》2023,62(14):e202219217
Lignin, the world's largest resource of renewable aromatics, with annually roughly 50 million tons of accruing technical lignin, mainly Kraft lignin, is highly underdeveloped regarding the production of monoaromatics. We demonstrate the oxidative depolymerization of Kraft lignin at 180 °C to produce vanillin 1 in yields up to 6.2 wt % and 92 % referred to the maximum yield gained from the quantification reaction utilizing nitrobenzene. Using peroxodicarbonate (C2O62−) as “green” oxidizer for the degradation, toxic and/or harmful reagents are prevented. Also, the formed waste can serve as makeup chemical in the pulping process. Na2C2O6 is synthesized in an ex-cell electrolysis of aqueous Na2CO3 at BDD anodes, achieving a yield of Na2C2O6 with 41 %. At least, the oxidation and degradation of Kraft lignin is analysis via UV/Vis and NMR spectroscopy. 相似文献
3.
Dr. Davide Piccinino Dr. Natalia Ceccotti Vlas Dr. Sofia Gabellone Dr. Eliana Capecchi Prof. Raffaele Saladino 《European journal of organic chemistry》2023,26(32):e202300356
Pummerer's ketones resembling the tricyclic scaffold of bioactive natural substances were synthesized by blue-LED driven Horseradish Peroxidase oxidative coupling of substituted phenols in 2-methyltetrahydrofuran by using meso-tetraphenylporphyrin as photosensitizer and dioxygen as primary oxidant. The application of functionalized lignin nanoparticles as a renewable and efficient platform for the immobilization of the enzyme extended the effectiveness of the overall process to heterogeneous catalysis under buffer limiting conditions. 相似文献
4.
Thorsten vomStein Tim denHartog Julien Buendia Spas Stoychev Jakob Mottweiler Carsten Bolm Jürgen Klankermayer Walter Leitner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(20):5957-5961
Ruthenium–triphos complexes exhibited unprecedented catalytic activity and selectivity in the redox‐neutral C C bond cleavage of the β‐O‐4 lignin linkage of 1,3‐dilignol model compounds. A mechanistic pathway involving a dehydrogenation‐initiated retro‐aldol reaction for the C C bond cleavage was proposed in line with experimental data and DFT calculations. 相似文献
5.
Lignin, as an abundant natural polymer with interesting mechanical, antimicrobial, and antioxidant properties, has the possibility to produce numerous chemicals and biofuels of current interest. However, the structural recalcitrance, heterogeneity, and complex extraction methods of lignin can hinder its transformation into value-added materials. Therefore, the research community is exploring innovative bioconversion technologies capable of effectively valorizing lignin. Thus, effective bioconversion and deconstruction methods have been recently studied. In this review, we first define lignin as a versatile raw material considering its characteristics, properties, and abundance. Then, lignin valorization is described in terms of the current opportunities and technical challenges. Finally, we discuss the industrial potential of lignin-derived products such as biofuels, biopolymers, biopesticides, and fertilizers. Those lignin-derived products are highly valuable for the energy and food industries, which are two main sectors challenged by the rapid growth of population, urbanization, and consumption. Thus, progress on lignin valorization would represent significant advancements in the Sustainable Development Goals (SDGs) and circular economy aspects. 相似文献
6.
7.
The aim of this study was to evaluate the influence of cellulose and/or lignin on the properties of mats prepared from dissolution (for 48 h or 72 h, solvent: trifluoroacetic acid) of recycled poly (ethylene terephthalate) (PET). Briefly, the presence of cellulose led to a tendency of higher average fiber diameter and average pore area as well as lower average porosity compared to the neat mat (PETref, 242 ± 59 nm, 9.6 ± 1.1 104 nm2 and 19.0 ± 1.1%, respectively). The Tg values for electrospun PET combined with cellulose and/or lignin were higher than that of PETref (92.5 ± 0.1 °C), and the tensile strength increased with the cellulose and/or lignin loading. In addition, the presence of lignin (72 h of dissolution) led to a mat with an elongation at break of 149 ± 9% compared to 14 ± 2% for PETref. The results indicated that the properties of mats based on PET can be tuned by adding cellulose and/or lignin to solutions posteriorly electrospun as well as by varying the dissolution time. 相似文献
8.
Juan Zhang Hesham S. Almoallim Sulaiman Ali Alharbi Baihui Yang 《Arabian Journal of Chemistry》2021,14(2):102934
Betulinic acid is one such natural pentacyclic triterpenoid compound, holding various pharmacological properties but its poor bioavailability is the only limitation. One of the biological macromolecules such as Lignin is a plant-derived aromatic, eco-friendly and low-cost polymer that certainly self-assembles into nano-sized colloids. Therefore, onto the current investigation, we increased the bioavailability of betulinic acid by coating on to a nanopolymer prepared with poly vinyl alcohol, lignins and methyl acrylate. Betulinic acid loaded polyvinyl alcohol/ethylacrylate grafted Lignin polymer (PVA/Lig-g-MA) nanoformulation was characterized using FTIR, XRD, SEM and TEM analysis and also the drug entrapment, in vitro drug releasing capacity was done to examine the efficiency of the nanoformulation of a drug. The MTT assay was evaluated the cytotoxicity of synthesized nanoformulation against normal endothelial cells HUVEC and HAPEC to confirm the side effects of the drug. The anti-atherosclerotic property of the nanoformulation was ascertained in both in vitro condition (with HUVEC and HPAEC) and in vivo studies (with Wistar rats). As a result, the characterization studies and in vitro studies clearly confirmed the Betulinic acid loaded PVA/Lig-g-MA nanoformulation is an ideal nanopolymer and it doesn’t cause any cytotoxic effect in normal endothelial cells. It also decreased the lipopolysaccharides induced inflammation through the down-regulation of NFκB and MAP/JNK signaling molecule expressions. Following in vivo results confirmed the synthesized nanoformulation effectively decreased the hyperchlostremia, inflammation and vasoconstriction, which induced over high fat diet. The results of histopathological analysis of cardiac tissues also confirmed the cardioprotective role of synthesized nanoformulation. Overall, both the in vitro and in vivo studies authentically proven the Betulinic acid loaded PVA/Lig-g-MA nanoformulation would be a potent cost effective anti-atherosclerotic nanodrug. 相似文献
9.
随着化石能源的不断枯竭,以及所产生的环境问题-温室效应及其高硫含量引起的酸雨,迫使人类寻找新型替代能源.在众多可再生能源中,生物质因其碳中性,易获取,作为唯一可转化为液体燃料的可再生资源,正日益受到重视.全球每年生物质产出高达1.7×1011t,其中,含75%的碳水化合物如纤维素、甲壳素和淀粉,20%木质素,其他占 相似文献
10.
Ryan Guterman Valerio Molinari Elinor Josef 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13178-13184
Ionic liquid lignins are prepared from sodium lignosulfonate by a cation exchange reaction and display glass transition temperatures as low as ?13 °C. Diethyleneglycol‐functionalized protic cations inhibit lignin aggregation to produce a free‐flowing “ionic liquid lignin”, despite it being a high‐molecular‐weight polyelectrolyte. Through this approach, the properties of both lignin and ionic liquids are combined to create a dispersant and binder for cellulose+gluten mixtures to produce small microphases. Biocomposite testing pieces are produced by hot‐pressing this mixture, yielding a material with fewer defects and improved toughness in comparison to other lignins. The use of unmodified lignosulfonate, acetylated lignosulfonate, or free ionic liquid for similar materials production yields poorer substances because of their inability to maximize interfacial contact and complexation with cellulose and proteins. 相似文献