Hydrothermal liquefaction process: Review and trends

Ocampo, Esteban; Beltrán, Victoria V.; Gómez, Elkin A.; Ríos, Luis A.; Ocampo, David

doi:10.1016/j.crgsc.2023.100382

Cited by 5 publications

(1 citation statement)

References 43 publications

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“…The decline in the use of fossil fuels has led the world to explore new resources and embrace renewables. Biomass, a renewable source, can be harnessed for energy production [1]. The European Union (EU) is making significant efforts to become the first climate-neutral region globally by 2050, emphasizing sustainable transportation with green fuels [2].…”

Section: Introductionmentioning

confidence: 99%

Sub-Supercritical Hydrothermal Liquefaction of Lignocellulose and Protein-Containing Biomass

Shah,

Sharma,

Seehar

et al. 2024

Fuels

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Hydrothermal liquefaction (HTL) is an emerging technology for bio-crude production but faces challenges in determining the optimal temperature for feedstocks depending on the process mode. In this study, three feedstocks—wood, microalgae spirulina (Algae Sp.), and hydrolysis lignin were tested for sub-supercritical HTL at 350 and 400 °C through six batch-scale experiments. An alkali catalyst (K2CO3) was used with wood and hydrolysis lignin, while e (Algae Sp.) was liquefied without catalyst. Further, two experiments were conducted on wood in a Continuous Stirred Tank Reactor (CSTR) at 350 and 400 °C which provided a batch versus continuous comparison. Results showed Algae Sp. had higher bio-crude yields, followed by wood and lignin. The subcritical temperature of 350 °C yielded more biocrude from all feedstocks than the supercritical range. At 400 °C, a significant change occurred in lignin, with the maximum percentage of solids. Additionally, the supercritical state gave higher values for Higher Heating Values (HHVs) and a greater amount of volatile matter in bio-crude. Gas Chromatography and Mass Spectrometry (GCMS) analysis revealed that phenols dominated the composition of bio-crude derived from wood and hydrolysis lignin, whereas Algae Sp. bio-crude exhibited higher percentages of N-heterocycles and amides. The aqueous phase analysis showed a Total Organic Carbon (TOC) range from 7 to 22 g/L, with Algae Sp. displaying a higher Total Nitrogen (TN) content, ranging from 11 to 13 g/L. The pH levels of all samples were consistently within the alkaline range, except for Wood Cont. 350. In a broader perspective, the subcritical temperature range proved to be advantageous for enhancing bio-crude yield, while the supercritical state improved the quality of the bio-crude.

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Section: Introductionmentioning

confidence: 99%

Sub-Supercritical Hydrothermal Liquefaction of Lignocellulose and Protein-Containing Biomass

Shah,

Sharma,

Seehar

et al. 2024

Fuels

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Hydrothermal liquefaction of catering wastes towards biofuel intermediates

Liakos,

Chrysikou,

Triantafyllidis

et al. 2024

Biomass Conv. Bioref.

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The potential application of the hydrothermal liquefaction process on catering wastes, spent coffee grounds (SCG) and orange peels, towards reducing municipal wastes was examined in this study, targeting to the production of biofuel intermediates. The study was focused on the two main process parameters, temperature (280–350 °C) and residence time (5–60 min) while the other parameters such as biomass/solvent ratio and applied extractant were selected according to literature. The results indicated that spent coffee grounds are a more promising feedstock, rendering higher bio-crude oil yield than orange peels (34 wt% and 22 wt% respectively). The optimal conditions for each feedstock varied due to their different structural properties, which not only affected the products’ yields but also their quality. To better understand the distribution of the process degradation products and a part of the reaction’s pathway, the gas product was analyzed via GC-FID, and the aqueous phase was studied via HPLC analysis. Finally, the bio-crude oil was subjected to elemental, thermogravimetric, and GC-MS analysis to determine its quality and biofuel potential, based on which the bio-crude oil derived from spent coffee grounds showed promising results while orange peel–derived oil is of lower value. According to the study’s findings, the bio-crude oil can be utilized as a fuel substitute after being upgraded via hydrotreatment enabling the heteroatoms removal and enhancing its fuel properties. Graphical abstract

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Hydrothermal liquefaction of wet microalgal biomass for biofuels and platform chemicals: advances and future prospects

Deepika,

Mrinal,

Pohrmen

et al. 2024

Discov Appl Sci

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Recent advances in hydrothermal liquefaction (HTL) have established this biomass conversion technology as a potent tool for the effective valorization and energy densification of varied feedstocks, ranging from lignocelluloses to microalgae and organic wastes. Emphasizing its application across biomass types, this exploration delves into the evolving landscape of HTL. Microalgae, recognized as a promising feedstock, offer a rich source of biomolecules, including lipids, carbohydrates, and proteins, making them particularly attractive for biofuel production. The comprehensive review explores the biofuel products and platform chemicals obtained through HTL of microalgae, delving into biodiesel production, bio-oil composition, characteristics, and to produce high-valued by-products. Challenges and limitations, such as reactor design, scalability issues, and the impact of microalgal composition on yields, are critically analyzed. The future prospects and research directions section envision advancements in HTL technology, integration with biorefinery processes, and the exploration of hybrid approaches for enhanced biofuel production. Overall, the paper emphasizes the promising potential of HTL for wet microalgal biomass and underscores the need for continued research to overcome existing challenges and unlock further opportunities in sustainable biofuel and platform chemical production.

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Hydrothermal liquefaction process: Review and trends

Cited by 5 publications

References 43 publications

Sub-Supercritical Hydrothermal Liquefaction of Lignocellulose and Protein-Containing Biomass

Sub-Supercritical Hydrothermal Liquefaction of Lignocellulose and Protein-Containing Biomass

Hydrothermal liquefaction of catering wastes towards biofuel intermediates

Hydrothermal liquefaction of wet microalgal biomass for biofuels and platform chemicals: advances and future prospects

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