Pyrolysis Of Lignin Research Articles

Insight into the fast pyrolysis of lignin: Unraveling the role of volatile evolving and char structural evolution

Unraveling the role of volatile evolving and char structural evolution, as well as the pyrolysis reaction pathway, is crucial for lignin effective valorization by a pyrolysis-based biorefinery approach. The fast pyrolysis of lignin at 200–800 °C was conducted to explore volatile release characteristics and their link with char structure evolution. The release of simple substituted aryl compounds below 350 °C was aided by the cleavage of β-O-4 and α-O-4. The C-O, C–C, and carboxyl groups of the depolymerized free radical fragments were cleaved further, providing stable mono-phenol (350 °C → 500 °C). Secondary reactions and pyrolytic macromolecular compounds resulted in the synthesis of polycyclic aromatic hydrocarbons (>700 °C). A cubic polynomial was developed to correlate the aromaticity with the atom ratio of H/C. The ring condensation degree and H/C demonstrated an excellent positive linear correlation. Additionally, the aromatization started at 350 °C, and small aromatic rings were changed into more ordered rings (≥6 rings). The fused-ring structures of char had progressed in the following order: 1 × 2, 2 × 3, 4 × 4, and 4 × 5, corresponding to 350 °C, 500 °C, 600 °C, and 800 °C, respectively. High temperatures contributed to the formation of aromatic monomers. Lignin pyrolysis pathway was established based on the correlation between volatile release characteristics and char structural evolution.

Co-pyrolysis of light bio-oil leached bamboo and heavy bio-oil: Effects of mass ratio, pyrolysis temperature, and residence time on the biochar

Light fraction of bio-oil (LB) has high contents of water and organic acids with good liquidity and is a promising leaching agent for deashing of biomass. Heavy fraction of bio-oil (HB) contains more amounts of phenols and pyrolytic lignin, has poor fluidity, and is easy to carbonize when heated. In this study, a novel method for preparation of biochar from co-pyrolysis of HB and LB leached bamboo (LB-bamboo) has been proposed. Effects of three experimental variables, namely, mass ratio (1:0–0:1), pyrolysis temperature (400–700 °C), and residence time (5–30 min), on the mass yield and properties of biochar were investigated, based on response surface methodology. Results showed that co-processing of HB and bamboo by pyrolysis synergistically improved the yield and higher heating value (HHV) of biochar. Under typical co-pyrolysis conditions (mass ratio 1:1, 550 °C, and 17.5 min), the experimentally determined yield (25.97%) and HHV (29.43 MJ/kg) of biochar from co-pyrolysis of HB and raw bamboo were 1.61% and 1.01 MJ/kg higher than the corresponding theoretically predicted values. The ash and metallic species in bamboo were significantly removed by LB leaching pretreatment, leading to a more synergistic effect observed during the subsequent co-pyrolysis. The experimentally determined yield (24.63%) and HHV (30.62 MJ/kg) of biochar from co-pyrolysis of HB and LB-bamboo were 2.40% and 1.57 MJ/kg higher than the corresponding theoretical values. Ultimately, the regression equations between the biochar properties and the three experimental variables were established. The best fitting models for yield and HHV of biochar were quadratic regression equations.

Revealing G-lignin model compounds pyrolysis behavior: β-O-4 and 5-5′ dimer and trimer

It is anticipated that the insight into the formation of the pyrolysis products would contribute to a fundamental understanding of the bond cleavage mechanism. Herein, in order to have a better understanding of the lignin pyrolysis property, the lignin pyrolysis property was investigated by using multi-scale lignin model components. The TGA and Py-GC/MS data indicated that even the lignin trimer contains both of the β-O-4 and 5-5′ chemical structures can be cleaved simultaneously and multiple bond cleavage mechanisms come into play, any of which has an effect on each other. But, overall, the low pyrolysis temperature (450–550 °C) is conducive to the enrichment of guaiacols as the main bio-oil, especially for guaiacol. This evidence could provide theoretical support for the pyrolysis of softwood lignin and the guidance for industrial lignin's high-value utilization and directional conversion.

The Sorption of Sulfamethoxazole by Aliphatic and Aromatic Carbons from Lignocellulose Pyrolysis

Massive biomass waste with lignocellulose components can be used to produce biochar for environmental remediation. However, the impact of lignocellulose pyrolysis on biochar structure in relation to the sorption mechanism of ionizable antibiotics is still poorly understood. In this paper, diverse techniques including thermogravimetric analysis and 13C nuclear magnetic resonance were applied to investigate the properties of biochars as affected by the pyrolysis of cellulose and lignin in feedstock. Cellulose-derived biochars possessed more abundant groups than lignin-derived biochars, suggesting the greater preservation of group for cellulose during the carbonization. Higher sorption of sulfamethoxazole (SMX) was also observed by cellulose-derived biochars owing to hydrogen bond interaction. Sorption affinity gradually declined with the conversion aliphatic to aromatic carbon, whereas the enhanced specific surface area (SSA) subsequently promoted SMX sorption as evidenced by increased SSA-N2 and SSA-CO2 from 350 to 450 °C. The decreased Kd/SSA-N2 values with increasing pH values implied a distinct reduction in sorption per unit area, which could be attributed to enhanced electrostatic repulsion. This work elucidated the role of carbon phases from thermal conversion of lignocellulose on the sorption performance for sulfonamide antibiotics, which will be helpful to the structural design of carbonaceous adsorbents for the removal of ionizable antibiotics.

Catalytic pyrolysis of lignin with metal-modified HZSM-5 as catalysts for monocyclic aromatic hydrocarbons production

This work aimed to investigate the feasibility of using metal-modified (Fe, Co, Ni, Cu, Zn, Ga) HZSM-5 zeolite as catalysts for high-value monocyclic aromatic hydrocarbons production via lignin catalytic pyrolysis in a two-stage fixed bed reactor. The structure-performance relationship of the catalysts was revealed based on the catalytic reaction testing results along with the acidity and textural properties obtained via systematic physicochemical characterization techniques, thus guiding the selection of the best modification metal and the optimal loading amount. As demonstrated, the 1 wt% Co modified HZSM-5 (1%Co-HZ) exhibited relatively slight coverage effect on the active sites, while increased the mesoporous surface area and average pore size of the parent HZSM-5 zeolite. Consequently, enhanced mass-transfer efficiency was attained by the 1%Co-HZ catalyst, which achieved the highest monocyclic aromatic hydrocarbons content (29.3%) among all the investigated metal-modified HZSM-5 catalysts. In addition, the Co modified sample showed better resistance to carbon deposition than that of the unmodified one. Overall, 1%Co-HZ can be used as an effective catalyst for monocyclic aromatic hydrocarbons production in lignin catalytic pyrolysis.

Pyrolysis of lignin (De–alkaline) via TG/DSC–FTIR and TG–MS: pyrolysis characteristics, thermo-kinetics, and gas products

Pyrolysis of lignin (De–alkaline) via TG/DSC–FTIR and TG–MS: pyrolysis characteristics, thermo-kinetics, and gas products

Enhancing water repellency and decay resistance of wood by using water-soluble fractions separated from pyrolytic lignin of fast-pyrolysis bio-oil

Biocides with lower environmental and human health impacts have been demanded by the society. Based on bioeconomy concepts, we investigated the potential of water-soluble fractions separated from the pyrolytic lignin of fast-pyrolysis bio-oil for wood protection against physical and biological agents. The high-viscosity crude bio-oil was fractionated in two oil-to-water ratios, 1:50 and 1:100, by separating the pyrolytic lignin and water-soluble fractions. Additionally, exfoliated nanostructures of bentonite were incorporated into water-soluble fractions to form bicomponent systems to improve the protection degree. These materials were then characterized in terms of morphological, chemical, and biological features. The preservative formulations were impregnated into pinewood (Pinus taeda), with subsequent evaluation of the morphology, wettability, thermal aspects, and antifungal activity of treated wood to determine the degree of protection. The water-soluble fractions severely impacted the water repellency of wood with contact angles up to 115°, and normal growth of the decay fungi (Trametes versicolor and Gloeophyllum trabeum). Also, the addition of nanobentonite in the formulations improved the action of the water-soluble fractions against the physical and biological agents, specifically for G. trabeum the decay can be decreased around three times compared to untreated wood. The combined action of water-soluble fraction and nanobentonite supported the wood water repellency with time-dependent stability of the contact angle and excellent antifungal activity, which is partially explained by the chemical composition of the water-soluble fraction and physical barriers formed by the nanobentonite on the surface. Therefore, a single use of water-soluble fractions or in combination with nanobentonite has potential for application as a bio-based wood protection process.

Catalytic pyrolysis of lignin over ZSM-5, alkali, and metal modified ZSM-5 at different temperatures to produce hydrocarbons

Temperature and catalyst type greatly influence the chemical processes as well as the quality of the pyrolysis products. Catalytic fast pyrolysis (CFP) of lignin isolated from rice straw using three different catalysts was performed at different pyrolysis temperatures (450, 500, 550, and 600 °C) using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) to explore the suitable catalytic performance for hydrocarbon production. The shape selectivity and acidity of the three catalysts (ZSM-5, NaOH-modified ZSM-5 (0.4 M), and nickel modified ZSM-5 (8 wt.%)), showed a substantial effect on the product distribution during CFP of lignin. Ni-ZSM-5 (8 wt.%) demonstrated effective performance for the transformation of oxygenated compounds through demethoxylation and dehydroxylation into aromatics. The most suitable pyrolysis temperature for catalytic pyrolysis of lignin was 550 °C in which a maximum selectivity of 72% for hydrocarbon was obtained over Ni-ZSM-5 (8 wt.%) followed by ZSM-5 (0.4 M) and ZSM-5. This research provides a suitable pyrolysis temperature and catalyst for high hydrocarbon production from catalytic pyrolysis of lignin.

Engineering Lignin-Derived Carbon–Silicon Nanocomposite Electrodes: Insight into the Copyrolysis Mechanism and Process–Structure–Property–Performance Relationships

As a renewable source, available in a large quantity, it is rewarding to find applications for lignin with high added value. We report the use of lignin in synthesizing a three-dimensional, interconnected carbon/silicon nanoparticle (C/Si NP) composite material as a low-cost replacement to conventional anode materials synthesized using expensive and toxic solvents and binders such as polyvinylidene in today’s lithium-ion battery (LIB) manufacturing process. To understand how lignin pyrolysis chemistry and processing conditions affect the structure, mechanical property, and electrochemical performance of the synthesized electrode materials, the thermochemical conversion process was, for the first time, quantitatively investigated using analytical pyrolysis–gas chromatography–mass spectrometry (GC–MS) along with a suite of other analytical tools. Results suggest that the surface bonding interaction of the C/Si NPs was evolved from pristine Si to −Si–O–C–, to −O═Si═O–, with the increase of pyrolysis temperature. The −Si–O–C– bond plays a key role in enhancing the cohesive strength and thus improving the electrochemical performance of the Si composite electrode. The pyrolysis–GC–MS can serve as a useful tool to predict the optimal pyrolysis temperature or tailor the properties of the synthesized composite electrodes by controlling the pyrolysis conditions. This study elucidates the processing–structure–property–performance relationships among lignin pyrolysis chemistry, carbon material structure and properties, and the electrochemical performance of the resulting electrode materials. Such knowledge serves as a basis for designing lignin-derived composite materials for electrochemical energy storage applications.

The influence of solvent on the pyrolysis of organosolv lignins extracted from willow

• The oxygen containing functional groups in lignin varied with fractionation solvent. • The decomposition temperature for the three lignins floated from 352 to 398℃. • The pyrolysis of L-EAC and L-THF yielded guaiacol and 4-methylguaiacol dominantly. • The pyrolysis of L-GBL yielded 4-methylguaiacol and 4-ethylguaiacol dominantly. The targeted application of lignin needs deeper understanding of its physicochemical property. Herein, three kinds of organosolv lignin samples were obtained from willow using three typical organosolv-water co-solvents, and their properties and pyrolysis behaviors were studied by various characterization methods. It was found that the used solvents exerted different effects on lignin samples: lignin extracted from ethyl acetate-water co-solvent possessed more functional groups containing oxygen, and lignin extracted from γ-butyrolactone-water co-solvent contained more large-molecule fragments; the degradation temperature with the maximum rate in thermogravimetric analysis were 352, 384, and 398 ℃ for lignin samples extracted by ethyl acetate/tetrahydrofuran/γ-butyrolactone-water co-solvent, respectively. The cleavage of C α -C β linkage performed more acutely in pyrolysis of lignin extracted from γ-butyrolactone-water co-solvent, while the linkage of C 1 -C α in lignin extracted by ethyl acetate/tetrahydrofuran-water co-solvent was more fragile. With regard to the mono-phenolic products, the pyrolysis of lignin extracted from ethyl acetate-water co-solvent yielded guaiacol and 4-methylguaiacol dominantly, and lignin extracted by tetrahydrofuran-water co-solvent produced more guaiacol, 4-ethylguaiacol, and 4-methylguaiacol while lignin extracted by γ-butyrolactone-water co-solvent yielded the maximum amount of 4-methylguaiacol. In addition, the pyrolysis of lignin samples extracted by γ-butyrolactone-water co-solvent yielded only H 2 , CH 4 and CO as gaseous products while the other two yielded H 2 , CH 4 , CO and CO 2 .

Co–Pyrolysis of Lignin (De–Alkalization) and Coconut Shell Via Tg/Dtg–Ftir and Machine Learning Methods: Pyrolysis Characteristics, Gas Products, and Thermo–Kinetics

Co–Pyrolysis of Lignin (De–Alkalization) and Coconut Shell Via Tg/Dtg–Ftir and Machine Learning Methods: Pyrolysis Characteristics, Gas Products, and Thermo–Kinetics

Pyrolytic lignin: a promising biorefinery feedstock for the production of fuels and valuable chemicals

Pyrolysis oil from lignocellulosic biomass can be fractionated into a lignin and sugar fraction. We here provide a review on the structure, properties, depolymerisation strategies and applications for pyrolytic lignin in the framework of a biorefinery.

Pyrolysis and gas emissions characteristics of six tree species in Heilongjiang Province, China

Forest fuels are the basis of fire occurrences, while ground dead fuels are an important part of forest fuels. Undestanding the pyrolysis characteristics and gas emissions of forest fuels is of great significance to explore the effects of forest fire on atmospheric environment and carbon balance, as well as to prevent and combat forest fire. In this study, the thermogravimetric analysis and gas emission analysis were conducted on leaf litter of six tree species (Pinus sylvestris var. mongolica, Picea koraiensis, Fraxinus mandshurica, Juglans mandshurica, Quercus mongolica, Betula platyphylla) in Heilongjiang Province to explore the pyrolysis process and combustibility of forest fuels, to analyze their pyrolysis characteristics, pyrolysis kinetics characteristics, gas emission characteristics. A four-dimensional evaluation of their combustibility was conducted based on pyrolysis parameters. The results showed that the pyrolysis temperature of holocellulose in the leaves of those six tree species ranged in 143.31-180.48 ℃ at the beginning and 345.04-394.38 ℃ at the end, lignin pyrolysis temperature ranged in 345.04-394.38 ℃ at the beginning and 582.85-609.31 ℃ at the end. The pyrolysis of the six kinds of arbor blades during the pyrolysis process affected fuel ash content, quality and temperature of the total pyrolysis. The activation energies of two main pyrolysis stages of leaves of six tree species were 18.88-27.08 kJ·mol-1 and 13.25-27.54 kJ·mol-1, respectively, and the pre-exponential factors were 3.13-26.28 min-1 and 1.30-22.55 min-1. The holocellulose activation energy and pre-exponential factor of the pyrolysis stage for P. koraiensis, F. mandshurica, Q. mongolica, and B. platyphylla were greater than that of the lignin pyrolysis stage, while the opposite was true for P. sylvestris var. mongolica and J. mandshurica. The release amounts of CO and CO2 at the pyrolysis stage of the holocellulose was 535.16-880.11 mg·m-3 and 7004.97-10302.05 mg·m-3, and that at the pyrolysis stage of lignin was 240.31-1104.67 mg·m-3 and 20425.60-33946.68 mg·m-3, respectively. The release of CO and CO2 at the pyrolysis stage of healdellulose was less, but mass loss was greater than that at the pyrolysis stage of lignin. In the four-dimensional combustibility ranking of the six tree species leaves, B. platyphylla was the best ignitable, P. koraiensis was the most combustible, and P. sylvestris var. mongolica was the most sustainable and consumable. The ignitability was significantly positively correlated with pyrolysis kinetics parameters of the holocellulose, while the sustainability was negatively correlated with that of lignin.

On the absolute photoionization cross section and threshold photoelectron spectrum of two reactive ketenes in lignin valorization: fulvenone and 2-carbonyl cyclohexadienone.

We report the absolute photoionization cross section (PICS) of fulvenone and 2-carbonyl cyclohexadienone, two crucial ketene intermediates in lignin pyrolysis, combustion and organic synthesis. Both species were generated in situ by pyrolyzing salicylamide and dectected via imaging photoelectron photoion coincidence spectroscopy. In a deamination reaction, salicylamide loses ammonia yielding 2-carbonyl cyclohexadienone, a ketoketene, which further decarbonylates at higher pyrolysis temperatures to form fulvenone. We recorded the threshold photoelectron spectrum of the ketoketene and assigned the ground state (X̃+2A′′ ← X̃1A′) and excited state (Ã+2A′ ← X̃1A′) bands with the help of Franck–Condon simulations. Adiabatic ionization energies are 8.35 ± 0.01 and 9.19 ± 0.01 eV. In a minor reaction channel, the ketoketene isomerizes to benzpropiolactone, which decomposes subsequently to benzyne by CO2 loss. Potential energy surface and RRKM rate constant calculations agree with our experimental observations that the decarbonylation to fulvenone outcompetes the decarboxylation to benzyne by almost two orders of magnitude. The absolute PICS of fulvenone at 10.48 eV was determined to be 18.8 ± 3.8 Mb using NH3 as a calibrant. The PICS of 2-carbonyl cyclohexadienone was found to be 21.5 ± 8.6 Mb at 9 eV. Our PICS measument will enable the quantification of reactive ketenes in lignin valorization and combustion processes using photoionization techniques and provide advanced mechanistic and kinetics insights to aid the bottom-up optimization of such processes.

An experimental and modeling study on the catalytic effects of select metals on the fast pyrolysis of hardwood and softwood lignin

Thermocatalytic decomposition of lignin from computational and experimental perspectives.

Non-Isothermal Pyrolysis of Xylan and Lignin: A Hybrid Simulated Annealing Algorithm and Pattern Search Method to Regulate Distributed Activation Energies

Non-Isothermal Pyrolysis of Xylan and Lignin: A Hybrid Simulated Annealing Algorithm and Pattern Search Method to Regulate Distributed Activation Energies

Non-Isothermal Pyrolysis of Xylan and Lignin: A Hybrid Simulated Annealing Algorithm and Pattern Search Method to Regulate Distributed Activation Energies

Non-Isothermal Pyrolysis of Xylan and Lignin: A Hybrid Simulated Annealing Algorithm and Pattern Search Method to Regulate Distributed Activation Energies

Pyrolysis Of Lignosulfonates and Lignin (De–Alkalization) Via Tg/Dtg–Ftir/Ms and In–Situ Py–Pi–Tof/Ms: Pyrolysis Characteristics, Gas Products, Volatiles, and Thermo–Kinetics

Pyrolysis Of Lignosulfonates and Lignin (De–Alkalization) Via Tg/Dtg–Ftir/Ms and In–Situ Py–Pi–Tof/Ms: Pyrolysis Characteristics, Gas Products, Volatiles, and Thermo–Kinetics

Promotion of Biomass Pyrolytic Saccharification and Lignin Depolymerization Via Nucleophilic Reagents Quenching of the Carbonium Ions

Promotion of Biomass Pyrolytic Saccharification and Lignin Depolymerization Via Nucleophilic Reagents Quenching of the Carbonium Ions

Influence of the Porosity and Acidic Properties of Aluminosilicate Catalysts on Coke Formation During the Catalytic Pyrolysis of Lignin

Influence of the Porosity and Acidic Properties of Aluminosilicate Catalysts on Coke Formation During the Catalytic Pyrolysis of Lignin