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.

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...

Pyrolysis of Wood/Biomass for Bio-oil: A Critical Review

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

Renewable fuels and chemicals by thermal processing of biomass

Fast pyrolysis for production of liquids has developed considerably since the first experiments in the late 1970s. Many reactors and processes have been investigated and developed to the point where fast pyrolysis is now an accepted feasible and viable route to renewable liquid fuels, chemicals and derived products. It is also now clear that liquid products offer significant advantages in storage and transport over gas and heat. These advantages have caused greater attention to be paid to fast pyrolysis, leading to significant advances in process development. The technology of fast pyrolysis for liquids is noteworthy for the wide range of reactor configurations that have been developed to meet the stringent requirements for high yields of useful liquids, for use as a fuel in boilers, engines and turbines and as a source of chemical commodities. This review summarizes the key features of fast pyrolysis and the resultant liquid product and describes the major reaction systems and processes that have been developed over the last 20 years.

http://ehsan13967.persiangig.com/document/pyrolysis5.pdf

Fast pyrolysis processes for biomass

The initial development of additives to stabilize the viscosity of biocrude during long-term storage has produced dramatic results. The additives investigated were ethyl acetate, methyl isobutyl ketone and methanol, acetone, methanol, acetone and methanol, and ethanol. These additives represent three chemical families, which all demonstrated the ability to drastically reduce the aging rate of biocrude, as defined by the increase in viscosity with time. Accelerated aging tests were run at 90 °C to screen the additives. The additives not only lowered the initial viscosity at 40 °C by half but also reduced the aging rate of a hot gas filtered pyrolysis oil made from hybrid poplar (NREL run 175) by factors of 1−18 compared to the original pure oil. With the best additive, methanol, at a 10 wt % level in the pyrolysis oil, the modified biocrude was still a single-phase liquid and still met the ASTM No. 4 diesel fuel specification for viscosity even after 96 h exposure to 90 °C. Based on the aging rate at 90 °C...

Additives To Lower and Stabilize the Viscosity of Pyrolysis Oils during Storage

Complex interactions occur between the many competing and sequential chemical reactions during the pyrolysis of cellulose, making the prediction of the pyrolysis products relatively difficult. The purpose of this paper is to present cellulose pyrolysis as a comprehensible interaction of time, temperature and pressure. Appropriate kinetic data for seven first-order global reactions for the pyrolysis of cellulose were found in the literature. A mathematical model was developed, in which the seven reactions occurred simultaneously so long as the feedstock for the particular reaction existed. The seven differential equations representing the reaction rates were numerically integrated simultaneously to obtain the products of pyrolysis as a function of time, temperature, heating rate and pressure. This program was used to predict many results and trends observed in both slow and fast pyrolysis: very high yields of condensible vapors (primary oils) were predicted under high heating rates to modest final temperatures; high char yields were predicted for slow heating rates at low temperatures; high gas yields were predicted for fast pyrolysis at high temperatures.

A unified, global model for the pyrolysis of cellulose

A summary is presented on the developments in the state of the art of experimental direct liquefaction of biomass, and the technoeconomic studies carried out within the IEA Biomass Agreement liquefaction activities from 1983 to 1991. The objectives of the study are: to identify potential improvements in developing process concepts, and to evaluate technically and economically the processes in direct thermal liquefaction. The principal instrument utilized in assessing the new technologies was a technoeconomic assessment. A standard procedure was constructed. Balances were calculated for a 1000 dry t/d plant size. Feedstocks included wood, peat, and straw. The thermal efficiency in the fuel oil substitute and gasoline production from woody biomass is above 60 % and 50 %, respectively. At a wood cost of US$ 30/wet t (US$ 3.4/GJ), and with a capital recovery factor of 0.12, a fuel oil substitute could be produced at US$ 8/GJ. The estimated cost for the least expensive transportation fuel process would be US$ 12/GJ. Areas where more research is needed are highlighted.

Assessment of liquefaction and pyrolysis systems

A handicap facing both the producer and the user of fast-pyrolysis oils is the lack of a description of these oils that is adequate for commercial applications. These oils are highly oxygenated and are relatively immiscible with petroleum oils. Under the current IEA Biomass Energy Agreement, the new Pyrolysis Activity (PYRA) has taken on the task of establishing a useful description of a series of pyrolysis oils. This series roughly parallels that of petroleum fuel oils already described, so that with as few changes as possible to the users’ equipment, a bio-oil could be used in place of the equivalent petroleum-derived oil. The specifications for biomass pyrolysis oils differ in the density, heating value, water content, and corrosiveness. These proposed specifications are presented for discussion by the biomass conversion community and feedback to the Pyrolysis Activity.

Proposed Specifications for Various Grades of Pyrolysis Oils

The Liquefaction Group of the lEA Biomass Agreement has carefully studied and analyzed a thermochemical conversion process under development at the National Renewable Energy Laboratory (NREL, formerly the Solar Energy Research Institute). This process converts biomass to an aromatic gasoline product. Biomass is subjected to very rapid pyrolysis in a vortex reactor to maximize the formation of oil vapors. After the char is removed from the process stream, the oil vapors are immediately sent to a catalytic cracking reactor with ZSM-5 zeolite catalyst to form a mixture of aromatic gasoline and gaseous olefins. Subsequent processing recovers byproduct gaseous olefms and converts them to aromatic gasoline. The small amount of toxic benzene formed as an intermediate compound is alkylated to extinction to form relatively benign compounds with a higher octane, such as cumene. The narrow boiling range desired for tomorrow’s reformulated gasolines is maintained by recycling both the volatile light ends and the difficult-to-bum heavy ends to extinction. A gasoline with a very high blending octane is the primary product. It is expected that this product will command a premium price. The process features state-of-the-art energy-saving and waste-management techniques. Using a consistent and well documented approach, the technoeconomics of this process were determined for both a “present” case and a “potential” case. The difference between the product costs for these two cases serves as an incentive for further research and development (R&D).

James P. Diebold

Papers

Additives To Lower and Stabilize the Viscosity of Pyrolysis Oils during Storage

A unified, global model for the pyrolysis of cellulose

Assessment of liquefaction and pyrolysis systems

Proposed Specifications for Various Grades of Pyrolysis Oils

IEA Technoeconomic Analysis of the Thermochemical Conversion of Biomass to Gasoline by the NREL Process