scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Mechanisms of liquefaction and pyrolysis reactions of biomass

01 Apr 2000-Energy Conversion and Management (Pergamon)-Vol. 41, Iss: 6, pp 633-646
TL;DR: In the liquefaction process, the micellar-like broken down fragments produced by hydrolysis are degraded to smaller compounds by dehydration, dehydrogenation, deoxygenation and decarboxylation as mentioned in this paper.
About: This article is published in Energy Conversion and Management.The article was published on 2000-04-01. It has received 904 citations till now. The article focuses on the topics: Deoxygenation & Thermal depolymerization.
Citations
More filters
Journal ArticleDOI
01 Aug 2007-Fuel
TL;DR: In this article, the pyrolysis characteristics of three main components (hemicellulose, cellulose and lignin) of biomass were investigated using, respectively, a thermogravimetric analyzer (TGA) with differential scanning calorimetry (DSC) detector and a pack bed.

5,859 citations


Additional excerpts

  • ...[22]....

    [...]

Journal ArticleDOI
TL;DR: A review of the recent developments in the wood pyrolysis and reports the characteristics of the resulting bio-oils, which are the main products of fast wood pyrotechnics, can be found in this paper.
Abstract: Fast pyrolysis utilizes biomass to produce a product that is used both as an energy source and a feedstock for chemical production. Considerable efforts have been made to convert wood biomass to liquid fuels and chemicals since the oil crisis in mid-1970s. This review focuses on the recent developments in the wood pyrolysis and reports the characteristics of the resulting bio-oils, which are the main products of fast wood pyrolysis. Virtually any form of biomass can be considered for fast pyrolysis. Most work has been performed on wood, because of its consistency and comparability between tests. However, nearly 100 types of biomass have been tested, ranging from agricultural wastes such as straw, olive pits, and nut shells to energy crops such as miscanthus and sorghum. Forestry wastes such as bark and thinnings and other solid wastes, including sewage sludge and leather wastes, have also been studied. In this review, the main (although not exclusive) emphasis has been given to wood. The literature on woo...

4,988 citations

Journal ArticleDOI
TL;DR: Several biomass hydrothermal conversion processes are in development or demonstration as mentioned in this paper, which are generally lower temperature (200-400 °C) reactions which produce liquid products, often called bio-oil or bio-crude.
Abstract: Hydrothermal technologies are broadly defined as chemical and physical transformations in high-temperature (200–600 °C), high-pressure (5–40 MPa) liquid or supercritical water. This thermochemical means of reforming biomass may have energetic advantages, since, when water is heated at high pressures a phase change to steam is avoided which avoids large enthalpic energy penalties. Biological chemicals undergo a range of reactions, including dehydration and decarboxylation reactions, which are influenced by the temperature, pressure, concentration, and presence of homogeneous or heterogeneous catalysts. Several biomass hydrothermal conversion processes are in development or demonstration. Liquefaction processes are generally lower temperature (200–400 °C) reactions which produce liquid products, often called “bio-oil” or “bio-crude”. Gasification processes generally take place at higher temperatures (400–700 °C) and can produce methane or hydrogen gases in high yields.

1,822 citations

Journal ArticleDOI
TL;DR: A review of modern biomass-based transportation fuels such as fuels from Fischer-Tropsch synthesis, bioethanol, fatty acid (m)ethylester, biomethanol, and biohydrogen are briefly reviewed in this paper.

1,505 citations


Cites background from "Mechanisms of liquefaction and pyro..."

  • ...The technology for making methanol from natural gas is already in place and requires only efficiency improvements and scale-up to make methanol an economically viable alternative transportation fuel [102]....

    [...]

Journal ArticleDOI
TL;DR: In this article, two general routes for bio-oil upgrading have been considered: hydrodeoxygenation (HDO) and zeolite cracking, where zeolites, e.g. HZSM-5, are used as catalysts for the deoxygenization reaction.
Abstract: As the oil reserves are depleting the need of an alternative fuel source is becoming increasingly apparent. One prospective method for producing fuels in the future is conversion of biomass into bio-oil and then upgrading the bio-oil over a catalyst, this method is the focus of this review article. Bio-oil production can be facilitated through flash pyrolysis, which has been identified as one of the most feasible routes. The bio-oil has a high oxygen content and therefore low stability over time and a low heating value. Upgrading is desirable to remove the oxygen and in this way make it resemble crude oil. Two general routes for bio-oil upgrading have been considered: hydrodeoxygenation (HDO) and zeolite cracking. HDO is a high pressure operation where hydrogen is used to exclude oxygen from the bio-oil, giving a high grade oil product equivalent to crude oil. Catalysts for the reaction are traditional hydrodesulphurization (HDS) catalysts, such as Co–MoS2/Al2O3, or metal catalysts, as for example Pd/C. However, catalyst lifetimes of much more than 200 h have not been achieved with any current catalyst due to carbon deposition. Zeolite cracking is an alternative path, where zeolites, e.g. HZSM-5, are used as catalysts for the deoxygenation reaction. In these systems hydrogen is not a requirement, so operation is performed at atmospheric pressure. However, extensive carbon deposition results in very short catalyst lifetimes. Furthermore a general restriction in the hydrogen content of the bio-oil results in a low H/C ratio of the oil product as no additional hydrogen is supplied. Overall, oil from zeolite cracking is of a low grade, with heating values approximately 25% lower than that of crude oil. Of the two mentioned routes, HDO appears to have the best potential, as zeolite cracking cannot produce fuels of acceptable grade for the current infrastructure. HDO is evaluated as being a path to fuels in a grade and at a price equivalent to present fossil fuels, but several tasks still have to be addressed within this process. Catalyst development, understanding of the carbon forming mechanisms, understanding of the kinetics, elucidation of sulphur as a source of deactivation, evaluation of the requirement for high pressure, and sustainable sources for hydrogen are all areas which have to be elucidated before commercialisation of the process.

1,487 citations

References
More filters
Book
01 Jun 1977
TL;DR: Localized Chemical bonding Delocalized Chemical Bonding Bonding Weaker than Covalent Stereochemistry Carbocations, Carbanions, Free Radicals, Carbenes and Nitrenes Mechanisms and Methods of Determining them Photochemistry Acids and Bases Effects of Structure on Reactivity Aliphatic Nucleophilic Substitution Aromatic Electrophilic Substitutes Aliphatically Electrophilic Substitution Free-Radical Substitution Addition to Carbon-Carbon Multiple Bonds Adding to Carbon Hetero Multiple Bonds Eliminations Rearrangements Ox
Abstract: Localized Chemical bonding Delocalized Chemical Bonding Bonding Weaker than Covalent Stereochemistry Carbocations, Carbanions, Free Radicals, Carbenes and Nitrenes Mechanisms and Methods of Determining Them Photochemistry Acids and Bases Effects of Structure on Reactivity Aliphatic Nucleophilic Substitution Aromatic Electrophilic Substitution Aliphatic Electrophilic Substitution Free-Radical Substitution Addition to Carbon-Carbon Multiple Bonds Addition to Carbon- Hetero Multiple Bonds Eliminations Rearrangements Oxidations and Reductions The Literature of Organic Chemistry Classifications of Reactions by Type of Compound Synthesized.

4,885 citations

BookDOI
31 Jan 1983
TL;DR: The anatomy and chemistry of wood are described in detail, and with extensive reference to the literature, under the following headings: Introduction; Structure and ultrastructure; Chemical composition and analysis of wood; Cellulose; Polyoses (hemicelluloses); Lignin; Extractives; Distribution of the components within the wood cell wall; Constituents of bark; Reactions in acidic medium; reactions in alkaline medium; Influence of temperature; Degradation by light and ionizing rays; Microbial and enzymatic degradation; Aging and fossilization; Pul
Abstract: The anatomy and chemistry of wood are described in detail, and with extensive reference to the literature, under the following headings: Introduction; Structure and ultrastructure; Chemical composition and analysis of wood; Cellulose; Polyoses (hemicelluloses); Lignin; Extractives; Distribution of the components within the wood cell wall; Constituents of bark; Reactions in acidic medium; Reactions in alkaline medium; Influence of temperature; Degradation by light and ionizing rays; Microbial and enzymatic degradation; Aging and fossilization; Pulping processes; Derivatives of cellulose; and Utilization of wood and wood components for chemicals and energy. -- AATA

2,987 citations

Book
01 Jan 1964
TL;DR: The first part deals with the formation, anatomy and properties of wood, and the second part is important for the numerous means of identifying woods which it contains as discussed by the authors, including anatomical means, structural features, physical characteristics, figure as it is related to the various planes of cut, and by chemical means.
Abstract: This is a technical volume designed for use as a reference book and as a textbook. The first part deals with the formation, anatomy and properties of wood. The second part is important for the numerous means of identifying woods which it contains. There are discussions of the identification of wood by anatomical means, structural features, physical characteristics, figure as it is related to the various planes of cut, and by chemical means. Keys for identification are offered as are descriptions by species and complete physical data for woods native to the U.S. and Canada. Also included is a section on the identification of wood by its fiber. -- AATA

1,716 citations

Journal ArticleDOI
TL;DR: Later development, beginning with the dehydrogenation theory and experimental studies on the de-hydrogenative polymerization of p-hydroxycinnamyl alcohols, is reviewed in this article.
Abstract: Some pertinent results and views from the earlier history of lignin chemistry, pointing to the importance of the arylpropane skeleton, are outlined. Later development, beginning with the dehydrogenation theory and experimental studies on the dehydrogenative polymerization of p-hydroxycinnamyl alcohols, is then reviewed. Finally, recent degradative work resulting in a detailed picture of lignin structure is discussed.

1,586 citations

Journal ArticleDOI
T. E. Timell1
TL;DR: In this article, the present status of the chemistry of wood hemicelluloses is summarized, with special emphasis on recent contributions, and problems still to be solved in wood chemistry are discussed, and an attempt is made to predict future developments in this field.
Abstract: Following a brief review of the general chemical composition of wood, the present status of the chemistry of the wood hemicelluloses is summarized, with special emphasis on recent contributions. The distribution of the hemicelluloses in the various wood tissues and wood cells and over the cell wall of tracheids and fibers is discussed in somewhat more detail. In conclusion, problems still to be solved in the chemistry of wood hemicelluloses are mentioned, and an attempt is made to predict future developments in this field.

813 citations