Article
Engineering, Environmental
Zhenggang Gong, Guangxu Yang, Liulian Huang, Lihui Chen, Xiaolin Luo, Li Shuai
Summary: An efficient phenol-assisted depolymerisation (PAD) process was developed to selectively cleave methylene linkages in condensed lignins. Phenol served as a solvent to dissolve lignin and also scavenged methylene linkages to facilitate the depolymerisation. The PAD process achieved higher yields of lignin monomers and bisphenols compared to existing depolymerisation methods, and the residual polyphenols could be used in adhesive synthesis for plywood applications.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Chemistry, Physical
Raphaela Suess, Gottfried Aufischer, Lukas Zeilerbauer, Birgit Kamm, Gisa Meissner, Hendrik Spod, Christian Paulik
Summary: The conversion of lignocellulosic biomass into valuable chemicals and biofuels has gained attention from researchers. This study investigates the use of precious metal-loaded hydrotalcite catalysts for the depolymerization of organosolv lignin, aiming to minimize coke formation and maximize the production of valuable lignin oil and lignin tar fractions. The catalyst support, platinum loading, and second metal loading were examined, and various analytical techniques were used to determine the product fractions. Optimization led to significant improvements in the lignin oil and lignin tar fractions.
CATALYSIS COMMUNICATIONS
(2022)
Article
Forestry
Anders Ahlbom, Marco Maschietti, Rudi Nielsen, Merima Hasani, Hans Theliander
Summary: This study found that hydrothermal liquefaction can rapidly depolymerize kraft lignin in the initial stages, but as time progresses, there are less pronounced structural changes, indicating a recalcitrant carbon-carbon skeleton remains in the products. Additionally, the yields of char and monomers slowly increase with reaction time, necessitating careful tuning of the reaction time.
Article
Polymer Science
David Rodriguez-Escribano, Felipe de Salas, Rocio Pliego, Gisela Marques, Thomas Levee, Anu Suonpaa, Ana Gutierrez, angel T. Martinez, Petri Ihalainen, Jorge Rencoret, Susana Camarero
Summary: Lignins released in black liquors from kraft pulp mills are a valuable but underutilized source of aromatics. Enzymatic depolymerization of kraft lignins using alkaliphilic fungal laccases has been made possible by our recent enzyme-directed evolution approach, which generated laccases with high activity and stability at pH 10. Our study demonstrates the ability of these tailor-made laccases to oxidize, demethylate, and depolymerize eucalyptus kraft lignin at pH 10. However, in high enzyme and lignin concentrations, repolymerization of the oxidized products becomes dominant. To overcome this, we successfully conducted the enzymatic reaction in a bench-scale reactor coupled to a membrane separation system.
Article
Forestry
Anders Ahlbom, Marco Maschietti, Rudi Nielsen, Merima Hasani, Hans Theliander
Summary: Depolymerisation of kraft lignin under hydrothermal conditions was investigated at short residence times (1-12 min) with glycerol being used as a capping agent. The weight average molecular weight (M-w) of the products decreased within the first minute of residence time, with the inter-unit ether linkages breaking accordingly. Furthermore, the M-w of the product fractions decreased at increasing residence times, while the char yield increased. Short residence times thus appear to be beneficial for mitigating the formation of char. Also, addition of NaOH reduced the yield of char. Although the addition of glycerol caused a decrease in the M-w of the products, it seemed to increase the yield of char and therefore might not be a suitable capping agent for kraft lignin depolymerisation.
Article
Engineering, Environmental
Matej Zula, Edita Jasiukaityte-Grojzdek, Miha Grilc, Blaz Likozar
Summary: Benzyl phenyl ether (BPE) was used as a model compound to study the mechanism of alpha-O-4 bond cleavage in lignin. The selection of solvent, catalyst loading, and reaction temperature were considered. A mathematical model including thermodynamics and reaction kinetics was developed to describe the experimental data. The results indicate that a nucleophile in the system inhibits oligomerisation and plays a role in determining the reaction outcomes.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Energy & Fuels
Hongwei Zhu, Boyu Du, Yating Bai, Zheng Pan, Yang Sun, Xing Wang, Jinghui Zhou
Summary: This study investigates the effect of reaction time on the yield and distribution of products during base-catalyzed depolymerization (BCD) process for lignin depolymerization. The results reveal a chain reaction mechanism triggered by secondary depolymerization of methoxy groups, leading to high-yield or highly selective phenol products. By controlling the reaction time, the study suggests a cost-effective and efficient method for lignin depolymerization.
BIOMASS CONVERSION AND BIOREFINERY
(2022)
Review
Engineering, Environmental
Tina Rocnik, Blaz Likozar, Edita Jasiukaityte-Grojzdek, Miha Grilc
Summary: This review focuses on the mechanism, chemical reaction kinetics, and transport phenomena of lignin depolymerisation, as well as the recently introduced aspects in the field of lignin chemistry. It also discusses the modeling of heat and mass transfer during lignin depolymerisation and upgrade.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Agricultural Engineering
Carlos A. Vega-Aguilar, M. Filomena Barreiro, Alirio E. Rodrigues
Summary: In this study, lignins from various sources were oxidized using H2O2 and TS-1 catalyst, with Indulin AT showing the highest succinic acid yield. The catalytic conversion also resulted in high yields of malic acid, especially for Lignol lignin. Overall, the catalytic conversion of lignin to C-4-DCA shows potential to guide the production of renewable chemicals.
INDUSTRIAL CROPS AND PRODUCTS
(2021)
Article
Forestry
Gottfried Aufischer, Raphaela Suess, Birgit Kamm, Christian Paulik
Summary: This study demonstrates the potential of lignin depolymerisation to produce bio-based products that can replace common antioxidants and UV absorbers in the plastics and cosmetics industries. The depolymerisation process significantly improves the thermo-oxidative stability and antioxidant activity of the lignin products. The absorption of UV light by these depolymerisation products is comparable to commercial antioxidants.
Article
Energy & Fuels
Ajaikumar Samikannu, Jyri-Pekka Mikkola, Alina Tirsoaga, Vlad Tofan, Radu Claudiu Fierascu, Aurore Richel, Marian Nicolae Verziu
Summary: This study investigated the one-pot depolymerisation of formic acid lignin (FAL) and ammonia lignin (AL) extracted from Miscanthus plants using Ni- and/or Nb-doped SBA-15 as catalysts. The addition of Nb into the SBA-15 structure increased the acidity and promoted the selective cleavage of β-O-4 linkages in AL. The catalytic performance and stability of Ni-Nb-SBA-15 were influenced by the chemical composition of the lignin samples extracted from Miscanthus plants.
BIOMASS CONVERSION AND BIOREFINERY
(2022)
Review
Chemistry, Multidisciplinary
Emmanuel Mkumbuzi, Michael Nivendran Pillay, Werner Ewald van Zyl
Summary: The effective exploitation of lignin, the world's largest renewable source of aromatics, through microwave-assisted depolymerisation with hydrogen-donating solvents (HDS), is a promising technique. However, the complex structure of lignin and the diverse products generated during its degradation make the MAD reaction mechanisms complex and poorly understood. This review provides an overview of current research on MAD reaction mechanisms involving HDS, aiming to give researchers a comprehensive understanding and inspire innovation for more advanced methods with improved yields and selectivity.
GREEN PROCESSING AND SYNTHESIS
(2023)
Article
Materials Science, Paper & Wood
Anders Ahlbom, Marco Maschietti, Rudi Nielsen, Merima Hasani, Hans Theliander
Summary: The depolymerisation of softwood kraft lignin under hydrothermal conditions was investigated, with the addition of guaiacol in the reactor feed. It was found that guaiacol has an impact on both the molecular weights of the products and the formation of char.
NORDIC PULP & PAPER RESEARCH JOURNAL
(2023)
Article
Chemistry, Organic
Prabhat K. Maharana, Tanumay Sarkar, Subhradeep Kar, Siddhartha K. Purkayastha, Ankur K. Guha, Tharmalingam Punniyamurthy
Summary: Stereospecific C-N and C-O bond formation of oxiranes with diaziridines has been achieved using a bimetallic catalyst at room temperature, resulting in the production of tetrahydro-[1,3,4]-oxadiazines. Optically active oxiranes can be coupled with high optical purities (>96% ee). The practical significance of this method lies in its stereoselectivity, tolerance for various functional groups, mechanistic studies using DFT, and potential application in natural product modification.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Energy & Fuels
Sandip K. Singh, Babasaheb M. Matsagar, Paresh L. Dhepe
Summary: For the development of an effective lignocellulosic biomass conversion technology, it is important to characterize the composition and properties of the biomass. This study developed a simple method to quantitatively analyze the cellulose, hemicellulose, lignin, and silica content of wheat straw and bagasse samples. The results showed that the bagasse samples contained higher proportions of structural biopolymers. Lignin recovery using acid hydrolysis showed significant differences in properties, and depolymerization of the lignin samples using different catalysts yielded high product yields.
BIOMASS CONVERSION AND BIOREFINERY
(2022)
Article
Chemistry, Multidisciplinary
Xuemei Liu, Chaonan Cui, Shuoshuo Wei, Jinyu Han, Xinli Zhu, Qingfeng Ge, Hua Wang
Summary: This study presents a new strategy for designing efficient photocatalysts that can convert CO2 into hydrocarbons by utilizing synergistic catalytic sites. The findings provide a solution for the selective photocatalytic reduction of CO2 to CH4.
Article
Chemistry, Multidisciplinary
Chengxian Hu, Dan Wang, Lu Wang, Ying Fu, Zhengyin Du
Summary: A novel one-pot, three-component reaction conducted under electrochemical conditions was studied. The reaction involved 2-aminothiophenols, aldehydes, and malononitrile, using TBABF4 as an electrolyte and CuI as a catalyst. The proposed reaction mechanism suggested that CuI served as an electron relay. This method offers simplified operation, high atom economy, and mild reaction conditions.
Article
Chemistry, Multidisciplinary
Zhi Yang, Yu Chen, Linxi Wan, Yuxiao Li, Dan Chen, Jianlin Tao, Pei Tang, Fen-Er Chen
Summary: A highly enantioselective method for the complete hydrogenation of pyrimidinium salts using Ir/(S,S)-f-Binaphane complex as the catalyst was developed. This method provides easy access to fully saturated chiral hexahydropyrimidines, which are prevalent in many bioactive molecules. The reactions exhibit high yields and enantioselectivities under mild reaction conditions without additives. Successful application of this methodology in a continuous flow fashion further extends its practical utility.
Article
Chemistry, Multidisciplinary
Tina Jeoh, Jennifer Danger Nill, Wujun Zhao, Sankar Raju Narayanasamy, Liang Chen, Hoi-Ying N. Holman
Summary: In this study, the enzymatic hydrolysis of cellulose was investigated using real-time infrared spectromicroscopy. The spatial heterogeneity of cellulose was found to impact the hydrolysis kinetics. Hydration affected cellulose ordering, and Cel7A preferentially removed less extensively hydrogen bonded cellulose.
Article
Chemistry, Multidisciplinary
Tiphaine Richard, Walid Abdallah, Xavier Trivelli, Mathieu Sauthier, Clement Dumont
Summary: An effective method of grafting functionalities onto lignin based on glycerol carbonate has been developed using an efficient nickel-catalysed telomerisation reaction. This method allows lignin to have new reactive functions and reduces the glass transition temperatures of modified lignins, thereby expanding the application range of lignin-based resins.
Article
Chemistry, Multidisciplinary
Jing Qi, Xiyan Wang, Gan Wang, Srinivas Reddy Dubbaka, Patrick ONeill, Hwee Ting Ang, Jie Wu
Summary: This study presents a green and environmentally friendly approach for the synthesis of imides using electrocatalytic oxidation with H2O as the oxygen source. The method eliminates the need for toxic or expensive oxidants and achieves high yields under mild reaction conditions. It shows broad substrate compatibility and potential for industrial applications.
Article
Chemistry, Multidisciplinary
Babasaheb Sopan Gore, Lin-Wei Pan, Jun-Hao Lin, Yi-Chi Luo, Jeh-Jeng Wang
Summary: Here, we report a visible light-promoted intramolecular radical cascade reaction for the construction of fluorenol and naphthalene-fused cyclopropyl carbaldehyde derivatives. This method offers mild reaction conditions, a broad substrate scope, excellent step efficiency, and scalability, without the need for external chemical oxidants. The novelty of this protocol was demonstrated by synthesizing chrysene analogs and performing late-stage functionalizations.
Article
Chemistry, Multidisciplinary
Juho Antti Sirvio, Idamaria Romakkaniemi, Juha Ahola, Svitlana Filonenko, Juha P. Heiskanen, Ari Ammala
Summary: This article discusses the method of using supramolecular interaction between an aromatic hydrogen bond donor and lignin to achieve rapid delignification of softwood at low temperatures.
Article
Chemistry, Multidisciplinary
Yunyan Meng, Chunxiang Pan, Na Liu, Hongjiang Li, Zixiu Liu, Yao Deng, Zixiang Wei, Jianbin Xu, Baomin Fan
Summary: A novel visible light-driven synthesis method for 2,3-diamines has been developed, which has mild conditions, avoids the use of metal reagents, and can synthesize diamines and diols in one pot.
Article
Chemistry, Multidisciplinary
Mingqing Huang, Haiyang Huang, Mengyao You, Xinxin Zhang, Longgen Sun, Chao Chen, Zhichao Mei, Ruchun Yang, Qiang Xiao
Summary: A direct air-oxidized strategy for the synthesis of benzo[b]phosphole oxides was developed in this study. Arylphosphine oxides were transformed into phosphinoyl radicals, which were further combined with various alkynes to achieve the desired products. DFT calculations revealed the mechanism of phosphinoyl radical formation.
Article
Chemistry, Multidisciplinary
Anwei Wang, Jiayin Huang, Chunsheng Zhao, Yu Fan, Junfeng Qian, Qun Chen, Mingyang He, Weiyou Zhou
Summary: This study demonstrates an innovative strategy for the aerobic oxidation of C(sp(3))-H bonds using gamma-valerolactone. By optimizing the reaction conditions and utilizing specific catalysts, efficient oxidation of C(sp(3))-H bonds is achieved with good chemoselectivity in certain cases.
Article
Chemistry, Multidisciplinary
Shun Li, Likai Tong, Zhijian Peng, Bo Zhang, Xiuli Fu
Summary: Sulfide compounds show promise as electrocatalysts for water splitting, but their performance is limited by factors such as limited active sites and hindered substance transport. This study successfully prepared a high-entropy sulfide (ZnCoMnFeAlMg)(9)S-8, which reduced grain size and increased specific surface area, enabling the realization of a dual-functional catalyst with multiple catalytic sites. High entropy also modulated the electronic properties of sulfides, reducing the potential energy barrier for hydrolysis. This research introduces a new approach for functionalizing high entropy nanomaterials and improves the performance of water splitting catalysts.