A review on potential of green solvents in hydrothermal liquefaction (HTL) of lignin

Yiin, Chung Loong; Odita, Elatta bin; Lock, Serene Sow Mun; Cheah, Kin Wai; Chan, Yi Herng; Wong, Mee Kee; Chin, Bridgid Lai Fui; Quitain, Armando T.; Loh, Soh Kheang; Yusup, Suzana

doi:10.1016/j.biortech.2022.128075

Cited by 22 publications

(5 citation statements)

References 101 publications

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“…The phenolic compounds then undergo a polymerization reaction to form a solid residue. Although this process occurs at a slower rate compared to hydrolysis reactions, insoluble lignin can also form char through solid–solid transformations (partial polymerization leading to high molecular weight solid residues) . Phenolic compounds can also undergo condensation reactions to generate polycyclic aromatic hydrocarbons.…”

Section: Reaction Mechanism and Pathways Of Typical Componentsmentioning

confidence: 99%

“…This step includes not only the phenolic structures such as p-hydroxyphenol and mhydroxyphenol in lignin, but also the hydrolysis of the methoxy group in the methoxyphenol molecule to generate phenol and the corresponding methanol (i.e., hydrolysis and demethylation chemical reaction). 70 Second, C−C bonds on the aromatic rings may cleavage, leading to the formation of alkenes and phenols. This process can be viewed as the deconstruction of the aromatic ring, resulting in smaller molecular fragments (i.e., fragmentation of the aromatic ring).…”

Section: Reaction Mechanism and Pathways Of Typical Componentsmentioning

confidence: 99%

“…Although this process occurs at a slower rate compared to hydrolysis reactions, insoluble lignin can also form char through solid−solid transformations (partial polymerization leading to high molecular weight solid residues). 70 Phenolic compounds can also undergo condensation reactions to generate polycyclic aromatic hydrocarbons. This condensation reaction usually occurs between aromatic rings, resulting in the bonding of aromatic rings, and have relatively low molecular weight (i.e., condensation reaction).…”

Section: Reaction Mechanism and Pathways Of Typical Componentsmentioning

confidence: 99%

“…The hydrolysis reaction leads to the cleavage of phenolic hydroxyl groups, forming products such as phenol, phenolic aldehydes and phenolic ketones. This step includes not only the phenolic structures such as p-hydroxyphenol and m-hydroxyphenol in lignin, but also the hydrolysis of the methoxy group in the methoxyphenol molecule to generate phenol and the corresponding methanol (i.e., hydrolysis and demethylation chemical reaction) . Second, C–C bonds on the aromatic rings may cleavage, leading to the formation of alkenes and phenols.…”

Section: Reaction Mechanism and Pathways Of Typical Componentsmentioning

confidence: 99%

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A Review of Hydrothermal Biomass Liquefaction: Operating Parameters, Reaction Mechanism, and Bio-Oil Yields and Compositions

Bao,

Wang,

Feng

et al. 2024

Energy Fuels

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Biomass hydrothermal liquefaction (HTL) is a conversion technology that utilizes high-temperature and high-pressure hydrothermal conditions to convert biomass into liquid fuels and chemicals. This review introduces all aspects of biomass HTL from system process parameters to reaction mechanism pathways and product control methods. First, the effects of key process parameters such as biomass composition, moisture content, heating rate, temperature, residence time, and pressure on the reaction process and product characteristics of HTL were discussed. Next, the reaction mechanism studies of typical components were reviewed. For typical components such as proteins, lipids, and carbohydrates, their reaction mechanisms and reaction pathways during the HTL process were explored. Understanding the reaction mechanisms of typical components can help to deeply understand the reaction characteristics of the entire HTL process. In terms of HTL product characteristics and product catalytic control, the properties and potential application values of the main components of the product, including bio-oil, the aqueous phase, and solid and gaseous products, were analyzed, and methods for product catalytic control were discussed. It introduced the methods and catalytic mechanism of adding additives and using catalysts to improve product characteristics. Finally, the challenges and technical difficulties faced by biomass hydrothermal liquefaction technology were discussed, and the future development direction was prospected.

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Section: Reaction Mechanism and Pathways Of Typical Componentsmentioning

confidence: 99%

Section: Reaction Mechanism and Pathways Of Typical Componentsmentioning

confidence: 99%

Section: Reaction Mechanism and Pathways Of Typical Componentsmentioning

confidence: 99%

Section: Reaction Mechanism and Pathways Of Typical Componentsmentioning

confidence: 99%

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A Review of Hydrothermal Biomass Liquefaction: Operating Parameters, Reaction Mechanism, and Bio-Oil Yields and Compositions

Bao,

Wang,

Feng

et al. 2024

Energy Fuels

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“…Higher temperatures of the HTL process provide the necessary activation energy to decompose lignin in the presence of water. In addition, desirable physicochemical properties, such as low dielectric constant, high ionic product, weak hydrogen bond, and high diffusivity at HTL conditions, catalyze the hydrolysis of biomass breaking down the hydrogen bonds of the cellulose structure to form sugar monomers via free radical reactions [56]. Hydrolysis and alkylation reactions rapidly convert lignin fragments into phenolic compounds, including catechols, phenols, guaiacols, etc.…”

Section: Hydrothermal Liquefaction (Htl)mentioning

confidence: 99%

Hydrothermal Conversion of Lignocellulosic Biomass to Hydrochar: Production, Characterization, and Applications

R. Chandraratne,

Gezae Daful

2024

From Biomass to Biobased Products

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The high moisture content poses a major technical barrier to using wet biomasses in thermochemical conversions. Hydrothermal conversions open efficient ways to convert wet biomass into carbonaceous products as an alternative to thermochemical methods such as pyrolysis, gasification, and combustion. Three types of hydrothermal conversions, hydrothermal carbonization (HTC), hydrothermal liquefaction (HTL), and hydrothermal gasification (HTG), use different operating conditions to convert wet biomass into distinct products: solid (hydrochar), liquid (aqueous soluble bio-oil), and gaseous fractions. Water plays a dominant role in hydrothermal conversions. HTC uses relatively mild conditions. HTL and HTG use subcritical and supercritical conditions, respectively. Conversion mechanisms and the effect of process parameters are also discussed in detail. The solid product hydrochar (HC) has properties comparable to biochar and activated carbon, hence a range of potential applications. Current and emerging applications of HC, including energy production and storage, soil amendment, wastewater treatment, carbon capture, adsorbent, and catalyst support, are discussed.

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Machine Learning Approach for Predicting Hydrothermal Liquefaction of Lignocellulosic Biomass

Katongtung,

Phromphithak,

Onsree

et al. 2024

Bioenerg. Res.

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A review on potential of green solvents in hydrothermal liquefaction (HTL) of lignin

Cited by 22 publications

References 101 publications

A Review of Hydrothermal Biomass Liquefaction: Operating Parameters, Reaction Mechanism, and Bio-Oil Yields and Compositions

A Review of Hydrothermal Biomass Liquefaction: Operating Parameters, Reaction Mechanism, and Bio-Oil Yields and Compositions

Hydrothermal Conversion of Lignocellulosic Biomass to Hydrochar: Production, Characterization, and Applications

Machine Learning Approach for Predicting Hydrothermal Liquefaction of Lignocellulosic Biomass

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