1.0. Introduction 4044 2.0. Biomass Chemistry and Growth Rates 4047 2.1. Lignocellulose and Starch-Based Plants 4047 2.2. Triglyceride-Producing Plants 4049 2.3. Algae 4050 2.4. Terpenes and Rubber-Producing Plants 4052 3.0. Biomass Gasification 4052 3.1. Gasification Chemistry 4052 3.2. Gasification Reactors 4054 3.3. Supercritical Gasification 4054 3.4. Solar Gasification 4055 3.5. Gas Conditioning 4055 4.0. Syn-Gas Utilization 4056 4.1. Hydrogen Production by Water−Gas Shift Reaction 4056

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Synthesis of transportation fuels from biomass: chemistry, catalysts, and engineering.

This paper provides an updated review on fast pyrolysis of biomass for production of a liquid usually referred to as bio-oil. The technology of fast pyrolysis is described including the major reaction systems. The primary liquid product is characterised by reference to the many properties that impact on its use. These properties have caused increasingly extensive research to be undertaken to address properties that need modification and this area is reviewed in terms of physical, catalytic and chemical upgrading. Of particular note is the increasing diversity of methods and catalysts and particularly the complexity and sophistication of multi-functional catalyst systems. It is also important to see more companies involved in this technology area and increased take-up of evolving upgrading processes. © 2011 Elsevier Ltd.

Review of fast pyrolysis of biomass and product upgrading

Biomass is an important feedstock for the renewable production of fuels, chemicals, and energy. As of 2005, over 3% of the total energy consumption in the United States was supplied by biomass, and it recently surpassed hydroelectric energy as the largest domestic source of renewable energy. Similarly, the European Union received 66.1% of its renewable energy from biomass, which thus surpassed the total combined contribution from hydropower, wind power, geothermal energy, and solar power. In addition to energy, the production of chemicals from biomass is also essential; indeed, the only renewable source of liquid transportation fuels is currently obtained from biomass.

The Catalytic Valorization of Lignin for the Production of Renewable Chemicals

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.

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Thermochemical biofuel production in hydrothermal media: A review of sub- and supercritical water technologies

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.

A review of catalytic upgrading of bio-oil to engine fuels

Influence of the Support of CoMo Sulfide Catalysts and of the Addition of Potassium and Platinum on the Catalytic Performances for the Hydrodeoxygenation of Carbonyl, Carboxyl, and Guaiacol-Type Molecules

The elimination of specific oxygenated groups of biomass-derived pyrolysis oils (bio-oils) is necessary for improving their stability. These are mainly unsaturated groups like alkene, carbonyl and carboxylic functions, as well as guaiacyl groups. For practical applications, it is desirable that the reactions are performed selectively in order to avoid excessive hydrogen consumption. The reactions must be done at relatively low temperature in order to limit competitive thermal condensation reactions. In this study, model oxygenated compounds were used, namely 4-methylacetophenone, diethyldecanedioate and guaiacol. They were tested simultaneously in one reaction test in the presence of sulfided cobalt-molybdenum and nickel-molybdenum supported on gamma-alumina catalysts in a batch system. Their reactivity and conversion scheme were determined. The ketonic group is easily and selectively hydrogenated into a methylene group at temperatures higher than 200 degrees C. Carboxylic groups are also hydrogenated to methyl groups, but a parallel decarboxylation occurs at comparable rates. A temperature around 300 degrees C is required for the conversion of carboxylic groups as well as for the conversion of the guaiacyl groups. The main reaction scheme of guaiacol is its transformation in hydroxyphenol which is subsequently converted to phenol. But in batch reactor conditions, guaiacol gives a high proportion of heavy products. CoMo and NiMo catalysts have comparable activities and selectivities. However, the NiMo catalyst has a higher decarboxylating activity than CoMo and also leads to a higher proportion of heavy products during the conversion of guaiacol.

Study of the Hydrodeoxygenation of Carbonyl, Carboxylic and Guaiacyl Groups Over Sulfided Como/gamma-al2o3 and Nimo/gamma-al2o3 Catalysts .1. Catalytic Reaction Schemes

Influence of Water in the Deactivation of a Sulfided Nimo Gamma-al2o3 Catalyst During Hydrodeoxygenation

The hydrotreatment of various oxygenated groups (ketonic, carboxylic, methoxyphenol) present in bio-oils in the presence of CoMo and NiMo catalysts was studied in a batch reactor using a mixture of model compounds mimicking the real feed. The influence of potential poisons or inhibitors of the reactions (water, ammonia and hydrogen sulfide) was determined. High quantities of water had only a very slight inhibiting effect on the reactions. Ammonia strongly inhibited the conversion of carboxylic esters and the removal of the methoxy group of guaiacol, but, surprisingly, the hydrogenation of the ketonic group was not affected. Hydrogen sulfide depressed the activity of the NiMo catalyst for the conversion of the ketonic group but not that of the CoMo catalyst. It had an enhancing effect on the conversion of the carboxylic ester group and no effect on the removal of the methoxy group of guaiacol. The evolution of activities and selectivities as a function of the concentration of potential inhibitors provided an indication of the catalytic sites responsible for the various reactions. The absence of the influence of ammonia on the hydrogenation of the ketonic group was interpreted as resulting from the participation of nucleophilic sites and hydridic species in the reaction mechanism. Carboxylic esters seem to react on electrophilic sites. Bronsted acids were thought to be responsible for decarboxylation, while uncoordinated metal atoms and sulfhydryl groups could be responsible for the hydrogenation of carboxylic groups. On the other hand, the surface of the alumina support catalyzes the hydrolysis of carboxylic esters into acids. The demethylation of guaiacol occurs for a large part on the Lewis acid-base sites of the gamma-alumina support. The use of hydrogen sulfide and ammonia shows a high potential for controlling the selectivity of reactions occurring in bio-oils hydrotreatment. The present results give hope that the deoxygenation of carboxylic groups could be selectively performed through decarboxylation thanks to catalyst selection and control of the hydrogen sulfide pressure. Ketonic groups and aldehydic groups could be selectively eliminated from complex feeds by applying a pressure of ammonia which would inhibit all reactions but hydrogenation.

Study of the Hydrodeoxygenation of Carbonyl, Carboxylic and Guaiacyl Groups Over Sulfided Como/gamma-al2o3 and Nimo/gamma-al2o3 Catalyst .2. Influence of Water, Ammonia and Hydrogen-sulfide

Etienne Laurent

Papers

Influence of the Support of CoMo Sulfide Catalysts and of the Addition of Potassium and Platinum on the Catalytic Performances for the Hydrodeoxygenation of Carbonyl, Carboxyl, and Guaiacol-Type Molecules

Study of the Hydrodeoxygenation of Carbonyl, Carboxylic and Guaiacyl Groups Over Sulfided Como/gamma-al2o3 and Nimo/gamma-al2o3 Catalysts .1. Catalytic Reaction Schemes

Influence of Water in the Deactivation of a Sulfided Nimo Gamma-al2o3 Catalyst During Hydrodeoxygenation

Study of the Hydrodeoxygenation of Carbonyl, Carboxylic and Guaiacyl Groups Over Sulfided Como/gamma-al2o3 and Nimo/gamma-al2o3 Catalyst .2. Influence of Water, Ammonia and Hydrogen-sulfide

Hydrotreatment of pyrolysis oils from biomass: reactivity of the various categories of oxygenated compounds and preliminary techno-economical study