Lignin-derived Chemicals Research Articles

Co-ZIF reinforced kraft lignin biochar as an efficient catalyst for highly selective hydrodeoxygenation of lignin-derived chemicals

Large amount of lignin was produced annually as a byproduct in papermaking and pulping processes, the challenges in disposal methods had posed serious obstacles for advanced carbon materials and value-added chemicals. This study involved the preparation of kraft lignin (KL) loaded metal–organic framework (ZIF-67) material derived Co nanoparticles carbon using various methods to produce kraft lignin biochar-based carbon materials (Co@NPC-KLB). The novel and advanced carbon materials was utilized for lignin derived bio-oil hydrodeoxygenation to generate high value fuels and chemicals. It could achieve nearly 100 % vanillin (VAN) conversion and 88.49 % 2-methoxy-4-methylphenol (MMP) without the extra hydrogen at 240 °C in ethanol. The results demonstrated that highly active and stable Co nanoparticles, large specific surface area, smaller nano Co nanoparticles, strong metal-support interaction and rich Lewis acid sites on the surface of biochar support exhibited a positive promoting effect on VAN hydrodeoxygenation to generate MMP. Furthermore, density functional theory (DFT) also confirmed that synergistic effect of Co nanoparticles and kraft lignin biochar promoted a high adsorption energy of VAN on the surface of kraft lignin biochar, enhanced the catalytic ability of the hydrodeoxygenation process. This study provided a novel approach for utilizing kraft lignin in preparation functional catalysts, opening up new opportunities for designing efficient biochar-based materials for advanced carbon materials and high-value chemicals.

Advancements and Perspectives toward Lignin Valorization via O-Demethylation.

Lignin represents the largest aromatic carbon resource in plants, holding significant promise as a renewable feedstock for bioaromatics and other cyclic hydrocarbons in the context of the circular bioeconomy. However, the methoxy groups of aryl methyl ethers, abundantly found in technical lignins and lignin-derived chemicals, limit their pertinent chemical reactivity and broader applicability. Unlocking the phenolic hydroxyl functionality through O-demethylation (ODM) has emerged as a valuable approach to mitigate this need and enables further applications. In this review, we provide a comprehensive summary of the progress in the valorization of technical lignin and lignin-derived chemicals via ODM, both catalytic and non-catalytic reactions. Furthermore, a detailed analysis of the properties and potential applications of the O-demethylated products is presented, accompanied by a systematic overview of available ODM reactions. This review primarily focuses on enhancing the phenolic hydroxyl content in lignin-derived species through ODM, showcasing its potential in the catalytic funneling of lignin and value-added applications. A comprehensive synopsis and future outlook are included in the concluding section of this review.

The Promising Future of Lignin Depolymerization in Biomass Valorization: Rajdeep Deka

Lignin is the second most abundant biopolymer besides cellulose in nature and accounts for a large fraction of biomass components in higher vascular plants, but this resource has been underutilized. Even though lignin, with its complex and highly heterogeneous structure, is difficult to extract from biomass and convert into valueadded compounds, large scale production of lignin-derived chemicals has the potential to promote a sustainable circular bioeconomy.

Herbaceous lignin valorization through integrated copper-catalyzed hydrogenolysis and chemical functionalization

Lignin is an important biomass resource to replace petrochemical industry for carbon neutrality. However, it is challenged by unyielding the trade-off between activity and selectivity owing to the chemical complexity and inherent heterogeneity of lignin biomacromolecule. Herein, we report that copper nanomaterial (CuO/C) derived from metal-organic framework (HKUST-1) could effectively catalytic hydrogenolysis of herbaceous plants into monomeric phenols (up to 29.5 wt%) through a lignin-first strategy, affording methyl 3-(4-hydroxyphenyl) propionate (1-H) and methyl 3-(4-hydroxy-3-methoxyphenyl) propionate (2-G) as the main monophenols with high selectivity of 31.9% and 17.3%. Moreover, we proposed two synthetic routes based on the purification and functionalization of those two compounds (1-H and 2-G) to synthesis 3-(4-carboxyphenyl) propionic acid and functional polyesters. Subsequent studies revealed that the temperature of 50% mass loss of the two polyesters reached 430–440 °C, indicating their robust thermal stability; while the DSC curves showed the difference between the two polymers in glass conversion temperature (Tg) and crystallization. In brief, this work opens a new avenue for the production of lignin-derived chemicals and materials.

Catalytic Pyrolysis of Lignin Model Compound (Ferulic Acid) over Alumina: Surface Complexes, Kinetics, and Mechanisms

Studies of the thermochemical properties of the important model compound of lignin-ferulic acid (FA) and its surface complexes are substantial for developing technologies for catalytic pyrolysis of renewable biomass into biofuels and lignin-derived chemicals as well as for bio-oil upgrading. In this work, the catalytic pyrolysis of ferulic acid over alumina was studied by temperature-programmed desorption mass spectrometry (TPD MS), in situ FT-IR spectroscopy, thermogravimetric analysis, and DFT calculations. We established that both the carboxyl group and the active groups (HO and CH3O) of the aromatic ring interact with the alumina surface. We calculated the kinetic parameters of formation of the main products of catalytic pyrolysis: 4-vinylguaiacol, guaiacol, hydroxybenzene, benzene, toluene, cresol, naphthalene, and PACs. Possible methods of their forming from the related surface complexes of FA are suggested.

Correction: Lignin amination valorization: heterogeneous catalytic synthesis of aniline and benzylamine from lignin-derived chemicals

Correction for ‘Lignin amination valorization: heterogeneous catalytic synthesis of aniline and benzylamine from lignin-derived chemicals’ by Yue Rong et al., Green Chem., 2021, DOI: 10.1039/d1gc02741g.

Lignin amination valorization: heterogeneous catalytic synthesis of aniline and benzylamine from lignin-derived chemicals

Using lignin derivatives as substrates, important organic nitrogen chemicals such as aniline and benzylamine can be obtained with high selectivity through heterogeneous catalyzed amination.

Preparation and Characterization of Various Kraft Lignins and Impact on Their Pyrolysis Behaviors

Lignin-derived chemicals and fuel products have received much attention in the context of bio-refinery. In this study we prepared and characterized various lignin samples from black liquor (BL), a major byproduct from the pulp and paper manufacturing processes, and studied the pyrolysis behaviors of these isolated lignin samples at 600 °C under a N2 atmosphere. Three lignin samples were isolated from the Kraft pulping BL of Loblolly pine linerboard grade process (KL, obtained by direct evaporation; L10, obtained by precipitation at pH 10; L3, obtained by precipitation at pH 3), while another three were from the Kraft pulping BL of Loblolly pine bleach grade process (KB, B10, B3). The inorganic elements present in lignin samples were analyzed using an inductively coupled plasma (ICP) analyzer. The KL and KB samples contained a larger amount of inorganic elements, especially Na and S, than did the other lignin samples. Owing to large quantities of inorganic elements, the ash contents in KL and KB were highe...

Selective hydrogenation of lignin-derived compounds under mild conditions

A key challenge in the production of lignin-derived chemicals is to reduce the energy intensive processes used in their production.

Biomass-Derived Poly(ether-amide)s Incorporating Hydroxycinnamates.

Lignin-derived chemicals have great potential as feedstock to produce polymeric materials, due to the low cost and high abundance of lignin biomass. Lignin is one of the few nonpetroleum sources of aromatic carbon, a desirable moiety in high-performance polymers. Herein we describe the synthesis and characterization of a series of 21 poly(ether-amide)s that incorporate hydroxycinnamates derived from lignin. Three different hydroxycinnamates (coumaric acid, ferulic acid, sinapinic acid) were incorporated into dimers, and then copolymerized with a series of seven aliphatic and aromatic diamines via interfacial polymerization. The resultant polymers exhibited poor solubility in standard organic solvents (excluding DMF), but exhibited moderate glass transition temperatures and moderate thermal stabilities. Additionally, the polymers exhibit excellent resistance to hydrolysis. The modularity of this synthetic approach could be used to rapidly generate diverse polymers with a broad range of well-tuned properties.

Catalytic Strategies Towards Lignin-Derived Chemicals.

Lignin valorization represents a crucial, yet underexploited component in current lignocellulosic biorefineries. An alluring opportunity is the selective depolymerization of lignin towards chemicals. Although challenged by lignin's recalcitrant nature, several successful (catalytic) strategies have emerged. This review provides an overview of different approaches to cope with detrimental lignin structural alterations at an early stage of the biorefinery process, thus enabling effective routes towards lignin-derived chemicals. A first general strategy is to isolate lignin with a better preserved native-like structure and therefore an increased amenability towards depolymerization in a subsequent step. Both mild process conditions as well as active stabilization methods will be discussed. An alternative is the simultaneous depolymerization-stabilization of native lignin towards stable lignin monomers. This approach requires a fast and efficient stabilization of reactive lignin intermediates in order to minimize lignin repolymerization and maximize the envisioned production of chemicals. Finally, the obtained lignin-derived compounds can serve as a platform towards a broad range of bio-based products. Their implementation will improve the sustainability of the chemical industry, but equally important will generate opportunities towards product innovations based on unique biobased chemical structures.

Characteristics of Lignin Extracted from Different Lignocellulosic Materials via Organosolv Fractionation

Among biomass-derived compounds, lignin is an underused component with potential for conversion to industrial-needed products in biorefinery. In this study, organosolv fractionation of four lignocellulosic materials including bagasse (BG), pararubber wood sawdust (PS), palm fiber (PF), and cassava fiber (CF) was studied using a ternary solvent mixture comprising methyl isobutyl ketone (MIBK), ethanol, and water in the presence of H2SO4 to separate high-purity lignin. The fractionation reaction was performed at 160 °C for 40 min with MIBK/ethanol/water proportion of 0.25/0.42/0.33 and 0.025 M of H2SO4, which led to the highest lignin removal efficiency of 88.2, 70.6, 67.3, and 71.7% (w/w) from BG, PS, PF, and CF, respectively. Physicochemical characteristics of the fractionated lignin were determined for Klason lignin and by X-ray fluorescence spectroscopy, organic elemental analysis, 1H nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. The lignin samples were thermally depolymerized in MIBK to determine the content of specific lignin-derived chemicals. The main phenolic derivatives from BG-lignin were 4-ethylphenol and 4-vinylguaiacol, whereas those from PS-lignin were syringaldehyde and cis-isoeugenol. Phenol and bis(2-ethylhexyl) phthalate were mainly produced from depolymerization of PF-lignin while trans-isoeugenol and hexadecanoic acid were the major products from CF-lignin. This work demonstrates the potential of the fractionated lignin for production of valuable chemicals in biorefineries.

Ga-doped Cu/H-nanozeolite-Y catalyst for selective hydrogenation and hydrodeoxygenation of lignin-derived chemicals

The development of an efficient non-sulfided and non-precious catalyst for selective hydrogenation (HD) and hydrodeoxygenation (HDO) of biomass-derived feedstocks to produce fuels and chemicals is of great interest.

Suggested Production of a Guaiacyl Benzofuran Derivative from Softwood via Lignocresol

Lignocresol was isolated from softwood with p-cresol using sulfuric acid and phase separation. An alkaline treatment of the lignocresol, followed by acidification, selectively yielded a guaiacyl coumaran, G1, in the acid-soluble fraction. With further alkaline treatment of G1 in 0.5 M of NaOH solution at 170 °C for 60 min, it was strongly suggested that a guaiacyl benzofuran derivative, G2, was obtained by the elimination of formaldehyde, based on analytical data of the reaction mixture. The process is very unique and well-designed based on the reactivity of Cα-ethers, or Cα-OH, Cβ-aryl-ethers, and Cγ-OH of lignin, although condensation reactions via formaldehyde occurred in parallel to give condensed products with a diarylmethane structure. Because these phenolic dimers, G1 and G2, were recovered from the guaiacyl unit linked with the neighboring guaiacyl units via two Beta-aryl-ether bonds, they are promising lignin-derived chemicals that are obtainable in a high yield.

Strategies for the Conversion of Lignin to High-Value Polymeric Materials: Review and Perspective.

The majority of commodity plastics and materials are derived from petroleum-based chemicals, illustrating the strong dependence on products derived from non-renewable energy sources. As the most accessible, renewable form of carbon (in comparison to CO2), lignocellulosic biomass (defined as organic matter available on a renewable basis) has been acknowledged as the most logical carbon-based feedstock for a variety of materials such as biofuels and chemicals. This Review focuses on methods developed to synthesize polymers derived from lignin, monolignols, and lignin-derived chemicals. Major topics include the structure and processing of lignocellulosic biomass to lignin, polymers utilizing lignin as a macromonomer, synthesis of monomers and polymers from monolignols, and polymers from lignin-derived chemicals, such as vanillin.

One-Pot Defunctionalization of Lignin-Derived Compounds by Dual-Functional Pd50Ag50/Fe3O4/N-rGO Catalyst

Generation of hydrogen from renewable sources and its safe utilization for efficient one-pot upgrading of renewable biofuels are a challenge. Bimetallic PdAg catalyst supported on Fe3O4/nitrogen-doped reduced graphene oxide (N-rGO) were synthesized for hydrogen generation from formic acid with high TOF (497 h–1 at 50 °C), and the hydrogen was subsequently utilized in situ for selective defunctionalization of lignin-derived chemicals with preserved aromatic nature at ambient pressure. Hydrodeoxygenation of aromatic aldehydes and ketones gave excellent yields (99% at 130 °C) with no use of additives. Furthermore, hydrogenolysis of β-O-4 and α-O-4 C–O model compounds produced only two products with high selectivity at 120 °C, which is an efficient and versatile one-pot platform for valorization of lignin biomass.

リグニンの有効利用

Although lignin in wood materials is to be separated as much as approximately a half of the amount of pulp through pulping processes, currently the chemical value of isolated polymeric lignin has not yet been effectively utilized. It has been desired to develop the processes for utilization of lignin in view of its chemical substance, i.e. highly complex polymer.In this review, first the outline of the present situation of lignin utilization in pulp and paper industries is presented in Section 1. Afterwards, the following three sections have been devoted from the standpoints of effective and potential utilization of lignin : Present situation of utilization of effective components and possibility or potentiality of utilization of derived components as chemical feedstocks (Section 2) Decomposition processes of lignin (Section 3) Possibility of utilization of decomposed components (Section 4).In Section 2, two typical reactions of lignin utilized for separation, i.e. acid catalyzed decomposition of ether likages and reductive decomposition of β-ether have been briefly described and the features of both reaction sequences offered along with practical applications. The necessity to clarify both the decomposition and condensation reactions quantitatively, that is, from the view point of chemical kinetics has been pointed out, because active sites for condensation reaction are apt to be still left after completion of both the reactions. Further, the steam explosion process of lignin, which is a practical process utilizing decomposition reaction of ether linkages is outlined and reactions and separations of derived components are explained to search for a possibility of their effective utilization.The first part of Section 3 is devoted to introduce several trials to degradate lignin chemically and thermally (pyrolysis) for chemical utilization. Hydrogenated decomposition, oxidative decomposition and production of catechol through a nucleophilic substitution reaction are reviewed as to chemical degradation. In the remaining part of this section, the biodegradation of lignin, i.e. the microbiology of lignin degradation, specifically lignin-degrading microbes and enzyme systems of lignin degradation, is reviewed. The latest trend and problems in the relevant fields are outlined and the long-term goals of biological processing of lignin are pressented.In Section 4, a feasibility study for production of polyoxyphenylene (or polyphenylene oxide, PPO) which is an important engineering plastic is given. The production of PPO is regarded as one of the promising processes for utilization of lignin-derived chemicals when the cost of lignin as well as the marcket scale of the product is taken into account.