Pyrolysis Oils from Biomass. Producing, Analyzing, and Upgrading

358 Pages·1988·5.93 MB·English

by  Ed J. Soltes and Thomas A. Milne (Eds.)

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376
ACS SYMPOSIUM SERIES
Pyrolysis Oils from Biomass
Producing, Analyzing, and Upgrading
Ed J. Soltes, EDITOR
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8 | Developed from a symposium sponsored by
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9 the Cellulose, Paper, and Textile Division
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30, and the Division of Fuel Chemistry
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American Chemical Society, Washington, DC 1988
Library of Congress Cataloging-in-Publication Data
Pyrolysis oils from biomass producing, analyzing, and upgrading.
(ACS Symposium Series; 376).
01 Developed from a symposium sponsored by the
0 Cellulose, Paper, and Textile Division and the Division of
6.fw FCuheelm Cichael mSiosctriyet ayt, Dtheen v1e9r3,r Cd oMloereatdino,g Aopf rtihl e5 -A1m0,e 1ri9c8a7n.
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3
8-0 Includes index.
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9 Bibliography: p.
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b 1. Biomass energy—Congresses. 2. Pyrolysis—
21/ Congresses. 3. Hydrocarbons—Congresses.
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1
0. I. Milne, Thomas Α. II. American Chemical Society.
1 Cellulose, Paper, and Textile Division. III. American
oi: Chemical Society. Division of Fuel Chemistry. IV. Title.
d V. Series.
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8 TP360.P95 1988 662'.8 88-24172
19 ISBN 0-8412-1536-7
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ept Copyright © 1988
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ACS Symposium Series
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1988 ACS Books Advisory Board
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0 Paul S. Anderson Vincent D. McGinniss
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6.f Merck Sharp & Dohme Research Battelle Columbus Laboratories
37 Laboratories
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8- Daniel M. Quinn
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9 Harvey W. Blanch
1 University of Iowa
k- University of California—Berkeley
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10 Malcolm H. Chisholm James C. Randall
10. Indiana University Exxon Chemical Company
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8 | Alan Elzerman E. Reichmanis
98 Clemson University AT&T Bell Laboratories
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er 3 John W. Finley C. M. Roland
mb Nabisco Brands, Inc. U.S. Naval Research Laboratory
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Se Natalie Foster
e: Lehigh University W. D. Shults
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D Oak Ridge National Laboratory
on Marye Anne Fox
cati The University of Texas—Austin Geoffrey K. Smith
ubli Rohm & Haas Co.
P Roland F. Hirsch
U.S. Department of Energy
Douglas B. Walters
National Institute of
G. Wayne Ivie
Environmental Health
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Purdue University Imperial Chemical Industries
Foreword
The ACS SYMPOSIUM SERIES was founded in 1974 to provide a
medium for publishing symposia quickly in book form. The
format of the Series parallels that of the continuing ADVANCES
IN CHEMISTRY SERIES except that, in order to save time, the
papers are not typeset but are reproduced as they are submitted
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0 by the authors in camera-ready form. Papers are reviewed under
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6.f the supervision of the Editors with the assistance of the Series
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03 Advisory Board and are selected to maintain the integrity of the
88- symposia; however, verbatim reproductions of previously pub
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k-1 lished papers are not accepted. Both reviews and reports of
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1/ research are acceptable, because symposia may embrace both
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10 types of presentation.
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Preface
PROLYSIS OF BIOMASS HAS undergone a technological renaissance in
the past decade, thanks to new concepts and processes for high oil yields,
new analytical techniques to decipher the mechanisms of formation and
constitution of the oil, and catalytic approaches to upgrading the oil fuel
used for transportation. Governments have given priority to pyrolysis
and direct liquefaction, following bench and pilot success in gasification
and indirect liquefaction, to offer industry concepts for renewable liquid
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0 fuels, particularly premium fuels. Following the Workshop1 on Fast
pr
6. Pyrolysis in 1980, and a series of liquefaction workshops in Canada2 in
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0 1980, 1982, and 1983, it seemed timely to convene scientists and
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8 engineers from North America and elsewhere to report on the present
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k- progress in integrated pyrolysis oil production, characterization, and
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1/ upgrading studies.
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0.1 As the book name implies, we attempted to bring together specialists
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oi: to present the state of the science in the complete fuel cycle, from
d feedstock to upgraded liquid fuels suitable as replacements for
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8 petroleum-derived fuels. The introductory chapter contains a discussion
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0, of biomass pyrolysis and its place in a renewable fuel economy. Contri
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er butions to this book were received from five countries, a fact indicating
mb the widespread interest in this conversion option for biomass, and per
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pt mitting the enhancement and establishment of collaborative efforts.
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e: At the time this preface was written, the U.S. newspapers reported a
Dat two-year low in crude oil prices ($15/Bbl), fleet auto efficiency standards
on were being relaxed, and oil imports were rising steadily. At the same
cati time, through perhaps a short-term statistical fluctuation in rainfall, the
ubli public was finally becoming aware of the implication of the real, long-
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term rise in C0 levels from deforestation and the burning of fossil
2
fuels. Perhaps the promise of a renewable source of liquid transporta
tion fuels, coupled with extensive reforestation, as mitigators of the rise
in C0 levels, will spur progress in the conversion of C0, through pho
2 2
tosynthesis, to plant materials. Such plant materials could provide facile
and economic routes to substitutes for fossil-based fuels, chemicals, and
biobased materials.
1. Diebold, J. P., Editor. Proceeding? of the Specialists Workshop on the Fast Pyrolysis of
Biomass. Copper Mountain, Colorado, Oct. 20-22 SERI/CP-622-10%.
2. ENFOR Program and National Research Council of Canada. Biomass Liquefaction
Specialists' Review Meetings in Toronto, Aug. 13, 1980; Saskatoon, Feb. 16-17, 1982;
and Sherbrooke, Sept. 29-30, 1983.
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We thank the sponsoring divisions and all contributors to this
volume and hope that their results will foster both interest in, and sup
port of, continuing work on the fascinating chemistry and engineering of
biomass pyrolysis, oil characterization, and upgrading for many uses.
ED J. SOLTES
Texas A&M University
College Station, TX 77843
THOMAS A. MILNE
Solar Energy Research Institute
Golden, CO 80401
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xii
Chapter 1
Of Biomass, Pyrolysis, and Liquids Therefrom
Ed J. Soltes
Department of Forest Science, Texas Agricultural Experiment Station,
Texas A&M University System, College Station, TX 77843-2135
Renewable biomass (harvest and process residues in forestry and agri
cultural operations, specific terrestrial or aquatic crops grown for fuel,
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00 often animal wastes, refuse derived fiber, etc.) represents an important
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c energy resource in the United States, with future potentials especially
6.
7 important as fossil fuels are depleted (1). Biomass is however generally
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8-0 poorly suited for direct energy use, with pretreatments necessary for
8 altering physical and chemical form. Moisture content can be in excess of
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k-1 50%, so costs of collection, transportation, and energy conversion become
b relatively inefficient. Further, biomass availability (e.g., from row crops) is
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2 sometimes seasonal, so storage is necessary. As biomass can spoil, it has to
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0.1 be covered and processed soon after receipt. Fortunately, thermal
oi: 1 aconnd vcearns iocno npvreortc ebsisoems aasrse isnotmo eswtahbalte ,i nssteonrasibtliev ea ntod ttyrpane,s pfoorrmta balned esnhearpgey,
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8 | forms, and in physical or chemical forms that can be used in higher
98 efficiency energy conversion processes developed for liquid petroleum, coal
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0, and natural gas. Under pyrolysis process conditions, a liquid tar (pyrolysis
ber 3 oil) cWanh yb e lipqruoiddu? cedI t wchainch bcea na breg uuepdg rtahdate d thtoe lipqruiindc iepnagl inaed vfauneltsa ge(2 ).o f
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e petroleum is that it is a liquid (3): liquid fuels, besides being energy
ept dense, are especially easy to store, transport and meter, thus being really
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e: the only choice for transportation fuels. Biomass conversion processes
at (specifically pyrolysis) which have potential for producing liquid fuels,
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n especially liquid fuels that can be direct replacements for gasoline or diesel
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ati engine fuels, are then of much interest.
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P The Nature of Biomass Pyrolysis
Biomass thermochemical processes have been studied for at least two
reasons: (1) a better understanding of the combustion process to control
biomass flammability; and, (2) research into improved processes for
converting biomass into useful energy forms. The late Fred Shafizadeh
(see, e.g., 4,5) laid the groundwork for all recent studies in both arenas.
The work on combustion mechanisms continues at the Wood Chemistry
Laboratory of the University of Montana in Missoula (see, e.g., 6). Antal
has recently (7,8) reviewed all aspects of biomass pyrolysis, and the reader
is directed to his reviews for detail study of the processes involved.
Chatterjee has produced an excellent summary (9) of biomass pyrolysis
0097-6156/88/0376-0001$06.00/0
° 1988 American Chemical Society
2 PYROLYSIS OILS FROM BIOMASS
rocesses relative to application in lesser developed countries. This author
as also written several reviews on biomass thermochemical processes, and
specifically pyrolysis (2,3,13). Several volumes have been published
recently on thermal conversion (10,11), with another on the way for the
1988 Phoenix conference (12).
The opening paragraph to this overview chapter relates the need for
pyrolysis relative to liquid transportation fuels production. This is a rather
specific energy need, and in fact, biomass can serve other energy needs as
well. Charcoal from wood is the principal fuel of rural regions of most
lesser developed countries. The gas from biomass gasification has found use
in the retrofit of natural gas furnaces and engines, and highly efficient
cogeneration plants. The energy content of residues from forestry and
agricultural operations can often serve on-site process energy needs, but
the biomass materials are generally poorly suited for direct use. Modern
agricultural and process machinery seldom use solid fuels, therefore
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0 pretreatments are often required to change their chemical or physical
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ch nature to liquids or gases. Similar considerations apply to the conversion
76. of biomass crops and to the use of biomass fuels off-farm. Thermochemical
03 processes for biomass are basically pretreatment processes, processes that
88- alter the chemical and physical nature of biomass to permit higher
19 efficiency use.
bk- Thermochemical processes are often characterized as combustion,
21/ gasification, pyrolysis, carbonization or tarification processes. Except for
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1 pyrolysis, these names reflect types of products produced. Thermochemical
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1 processing is variable and flexible. Depending on conditions used,
oi: (primarily the temperature, the oxygen-to-fuel ratio, and residence time at
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8 | temperature), biomass can be altered very slightly, or be completely
8 changed. These three variables define conditions for pyrolysis, gasification
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1 and combustion but there is often little distinction between these processes.
30, In fact, there is a continuum of process conditions. Selection of treatment
er conditions permits a variety of outcomes of importance to the production of
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m bioenergy products. The mechanisms for the formation of these products
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pt are indeed complex, and are still unfolding (see e.g., 7,8,14). Knowledge of
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S these mechanisms has permitted the identification of conditions under
ate: which it is possible to produce tars in good yield from large, moist wood
D particles (15), or novel reactor design for the production and capture of
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o desired tar products (16). Still, gases, liquids and solids are always
ati produced, with relative yields and chemical or elemental compositions
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Definition of Pyrolysis. The word pyrolysis has had some problems in
definition, especially when applied to biomass. The older literature
generally equates pyrolysis to carbonization, in which the principal pro
duct is a solid char. Today, the term pyrolysis is generally used to
describe processes in which liquid oils are preferred products. This
symposium was concerned with the latter pyrolysis - processes which offer
enhanced yields of liquid oils, especially those with desirable chemical
compositions and physical attributes for liquid fuels, fuel supplements and
chemical feedstocks.
Definition of Pyrolysis Oil vs. Tar. Throughout this volume,
"pyrolysis oil", "tar" and "pyrolytic tar" are used almost interchangeably.
Tar or pyrolytic tar is a more generic term, now becoming used in
reference to its formation in a secondary sense, e.g., as undesired in
gasification, or the "creosote tar" of incomplete combustion or the usually