Hydrothermal liquefaction of biomass

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Abstract

Biomass is one of the most abundant sources of renewable energy, and will be an important part of a more sustainable future energy system. In addition to direct combustion, there is growing attention on conversion of biomass into liquid en-ergy carriers. These conversion methods are divided into biochemical/biotechnical methods and thermochemical methods; such as direct combustion, pyrolysis, gasification, liquefaction etc. This chapter will focus on hydrothermal liquefaction, where high pressures and intermediate temperatures together with the presence of water are used to convert biomass into liquid biofuels, with the aim of describing the current status and development challenges of the technology.
During the hydrothermal liquefaction process, the biomass macromolecules are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive and can recombine into larger ones. During this process, a substantial part of the oxygen in the biomass is removed by dehy-dration or decarboxylation. The chemical properties of the product are mostly de-pendent of the biomass substrate composition. Biomass consists of various com-ponents such as carbohydrates; lignin, protein and fat, and each of them produce distinct groups of compounds when processed individually. When processed to-gether in different ratios, they will most likely cross-influence each other and thus the composition of the product. Processing conditions including temperature, pres-sure, residence time, catalyst, and type of solvent are important for the bio-oil yield and product quality.
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Biomass is one of the most abundant sources of renewable energy, and will be an important part of a more sustainable future energy system. In addition to direct combustion, there is growing attention on conversion of biomass into liquid en-ergy carriers. These conversion methods are divided into biochemical/biotechnical methods and thermochemical methods; such as direct combustion, pyrolysis, gasification, liquefaction etc. This chapter will focus on hydrothermal liquefaction, where high pressures and intermediate temperatures together with the presence of water are used to convert biomass into liquid biofuels, with the aim of describing the current status and development challenges of the technology.
During the hydrothermal liquefaction process, the biomass macromolecules are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive and can recombine into larger ones. During this process, a substantial part of the oxygen in the biomass is removed by dehy-dration or decarboxylation. The chemical properties of the product are mostly de-pendent of the biomass substrate composition. Biomass consists of various com-ponents such as carbohydrates; lignin, protein and fat, and each of them produce distinct groups of compounds when processed individually. When processed to-gether in different ratios, they will most likely cross-influence each other and thus the composition of the product. Processing conditions including temperature, pres-sure, residence time, catalyst, and type of solvent are important for the bio-oil yield and product quality.
Original languageEnglish
Title of host publicationApplication of hydrothermal reactions to biomass conversion
EditorsFangming Jin
PublisherSpringer Publishing Company
Publication date2014
Pages189-217
Chapter9
ISBN (Print)978-3-642-54457-6
ISBN (Electronic)978-3-642-54458-3
DOI
StatePublished - 2014
Publication categoryResearch
Peer-reviewedYes
SeriesGreen Chemistry and Sustainable Technology
ISSN2196-6982

    Research areas

  • Biomass, Liquefaction, Hydrothermal, Conversion, Bio oil
ID: 77468287