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

https://cmapspublic3.ihmc.us/rid=1N3976C22-12M3P49-9V/Holladay%20et%20al.%20-%202009%20-%20An%20overview%20of%20hydrogen%20production%20technologies.pdf

An overview of hydrogen production technologies

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

Wet algae slurries can be converted into an upgradeable biocrude by hydrothermal liquefaction (HTL). High levels of carbon conversion to gravity separable biocrude product were accomplished at relatively low temperature (350 °C) in a continuous-flow, pressurized (sub-critical liquid water) environment (20 MPa). As opposed to earlier work in batch reactors reported by others, direct oil recovery was achieved without the use of a solvent and biomass trace components were removed by processing steps so that they did not cause process difficulties. High conversions were obtained even with high slurry concentrations of up to 35 wt.% of dry solids. Catalytic hydrotreating was effectively applied for hydrodeoxygenation, hydrodenitrogenation, and hydrodesulfurization of the biocrude to form liquid hydrocarbon fuel. Catalytic hydrothermal gasification was effectively applied for HTL byproduct water cleanup and fuel gas production from water soluble organics, allowing the water to be considered for recycle of nutrients to the algae growth ponds. As a result, high conversion of algae to liquid hydrocarbon and gas products was found with low levels of organic contamination in the byproduct water. All three process steps were accomplished in bench-scale, continuous-flow reactor systems such that design data for process scale-up was generated.

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Process development for hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor

Catalytic hydroprocessing has been applied to biomass fast pyrolysis liquid product (bio-oil) in a bench-scale continuous-flow fixed-bed reactor system The intent of the research was to develop process technology to convert the bio-oil into a petroleum refinery feedstock to supplement fossil energy resources and to displace imported feedstock The project was a cooperative research and development agreement among UOP LLC, the National Renewable Energy Laboratory and the Pacific Northwest National Laboratory (PNNL) This article is focused on the process experimentation and product analysis undertaken at PNNL

This article describes the experimental methods used and relates the results of the product analyses A range of catalyst formulations were tested over a range of operating parameters including temperature, pressure, and flow rate with bio-oil derived from several different biomass feedstocks Effects of liquid hourly space velocity and catalyst bed temperature were assessed Details of the process results were presented included product yields and hydrogen consumption Detailed analysis of the products were provided including elemental composition, chemical functional type determined by mass spectrometry, and product descriptors such as density, viscosity, and total acid number In conclusion, this article provides an understanding of the efficacy of hydroprocessing as applied to bio-oil © 2009 American Institute of Chemical Engineers Environ Prog, 2009

Catalytic Hydroprocessing of Biomass Fast Pyrolysis Bio-oil to Produce Hydrocarbon Products

Bio-oil (product liquids from fast pyrolysis of biomass) is a complex mixture of oxygenates derived from the thermal breakdown of the biopolymers in biomass. In the case of lignocellulosic biomass, the structures of three major components, cellulose, hemicellulose and lignin, are well-represented by the bio-oil components. To study the chemical mechanisms of catalytic hydroprocessing of bio-oil, three model compounds were chosen to represent those components. Guaiacol represents the large number of mono- and dimethoxy phenols found in bio-oil derived from soft- or hardwood, respectively. Furfural represents a major pyrolysis product group from cellulosics. Acetic acid is a major product from biomass pyrolysis, derived from the hemicellulose, which has important impacts on the further processing of the bio-oil because of its acidic character. These three compounds were processed using a palladium or ruthenium catalyst over a temperature range from 150 to 300 °C. The batch reactor was sampled during each te...

Catalytic Hydroprocessing of Chemical Models for Bio-oil

This report provides a preliminary analysis of the costs associated with converting whole wet algal biomass into primarily diesel fuel. Hydrothermal liquefaction converts the whole algae into an oil that is then hydrotreated and distilled. The secondary aqueous product containing significant organic material is converted to a medium btu gas via catalytic hydrothermal gasification.

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Process Design and Economics for the Conversion of Algal Biomass to Hydrocarbons: Whole Algae Hydrothermal Liquefaction and Upgrading

Catalytic hydroprocessing has been applied to the fast pyrolysis liquid product (bio-oil) from softwood biomass in a bench-scale continuous-flow fixed-bed reactor system. The intent of the research was to develop process technology to convert the bio-oil into a petroleum refinery feedstock to supplement fossil energy resources and to displace imported feedstock. This paper is focused on the process experimentation and product analysis. A range of operating parameters, including temperature from 170 or 250 to 400 °C in the two-stage reactor and flow rate of 0.19 liquid hourly space velocity, was tested with bio-oil derived from pine wood. Times on stream of up to 90 h were evaluated, and losses of catalyst activity were assessed. Product yields of 0.35–0.45 g of oil product/g of dry bio-oil feed with hydrogen consumptions from 342 to 669 L/L of bio-oil feed were measured. Analyses determined that product oils with densities of 0.82–0.92 g/mL had oxygen contents of 0.2–2.7 wt % and total acid number (TAN) o...

Todd R. Hart

Papers

Process development for hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor

Catalytic Hydroprocessing of Biomass Fast Pyrolysis Bio-oil to Produce Hydrocarbon Products

Catalytic Hydroprocessing of Chemical Models for Bio-oil

Process Design and Economics for the Conversion of Algal Biomass to Hydrocarbons: Whole Algae Hydrothermal Liquefaction and Upgrading

Catalytic Hydroprocessing of Fast Pyrolysis Bio-oil from Pine Sawdust