U.S. patent application number 13/280982 was filed with the patent office on 2012-05-03 for process for producing high quality pyrolysis oil from biomass.
This patent application is currently assigned to CONOCOPHILLIPS COMPANY. Invention is credited to Daren Einar DAUGAARD, Kening GONG, Samuel T. JONES, Alexandru PLATON.
Application Number | 20120108860 13/280982 |
Document ID | / |
Family ID | 44910306 |
Filed Date | 2012-05-03 |
United States Patent
Application |
20120108860 |
Kind Code |
A1 |
DAUGAARD; Daren Einar ; et
al. |
May 3, 2012 |
PROCESS FOR PRODUCING HIGH QUALITY PYROLYSIS OIL FROM BIOMASS
Abstract
This invention relates to a process to utilize a torrefaction
pretreatment step for biomass pyrolysis process. This pretreatment
improves the quality of the pyrolysis oil by reducing acidity. The
inventive process shows that as a pretreatment to pyrolysis,
resulting pyrolysis oil obtained from torrefied biomass has
approximately 25% lower acetic acid than that from untorrefied
biomass pyrolysis oil.
Inventors: |
DAUGAARD; Daren Einar;
(Skiatook, OK) ; GONG; Kening; (Bartlesville,
OK) ; PLATON; Alexandru; (Bartlesville, OK) ;
JONES; Samuel T.; (Dewey, OK) |
Assignee: |
CONOCOPHILLIPS COMPANY
Houston
TX
|
Family ID: |
44910306 |
Appl. No.: |
13/280982 |
Filed: |
October 25, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61407994 |
Oct 29, 2010 |
|
|
|
Current U.S.
Class: |
585/14 ; 585/240;
585/242 |
Current CPC
Class: |
C10B 53/02 20130101;
Y02P 20/145 20151101; C10B 57/02 20130101; C10C 5/00 20130101; C10L
1/02 20130101; C07C 29/04 20130101; C10G 2300/1014 20130101; Y02P
30/20 20151101; C10B 57/08 20130101; C10G 2300/1018 20130101; C10G
2300/203 20130101; C10L 9/083 20130101; Y02E 50/10 20130101 |
Class at
Publication: |
585/14 ; 585/240;
585/242 |
International
Class: |
C10L 1/04 20060101
C10L001/04 |
Claims
1. A process for producing pyrolysis oil product from biomass
comprising at least the following steps: a) a step of subjecting a
biomass feedstock to a thermal treatment in a reactor A under a
torrefaction reaction condition to produce an torrefied biomass
feedstock; b) a step of pyrolyzing said torrefied biomass feedstock
in a reactor B under a pyrolysis reaction condition to form a
pyrolysis oil product, wherein said torrefaction reaction
conditions includes a temperature ranging from 180.degree. C. to
350.degree. C., a pressure ranging from 11 psia to 500 psia, and a
residence time ranging from 1 minute to 24 hours, wherein said
pyrolysis reaction conditions includes a temperature ranging from
375.degree. C. to 700.degree. C., a pressure ranging from 0.1 psia
to 1000 psia, and a residence time ranging from 0.1 to 200 second,
and wherein said pyrolysis oil product has a TAN number between 80
and 200.
2. The process of claim 1, wherein said torrefaction reaction
conditions includes a temperature ranging from 220.degree. C. to
280.degree. C., a pressure ranging from 11 psia to 30 psia, and a
residence time ranging from 5 to 20 minutes, wherein said pyrolysis
reaction conditions includes a temperature ranging from 425.degree.
C. to 525.degree. C., a pressure ranging from atmospheric pressure
to 300 psia., and a residence time ranging from 0.5 to 2 seconds,
and wherein said pyrolysis oil product has a TAN number between 20
and 50.
3. The process either claim 1 or 2, wherein said torrefaction
reaction is carried out in said reactor A selected from a group
consisting of an augers reactor, an ablative reactor, a rotating
cones reactor, a fluidized-bed reactor, an entrained-flow reactor,
a vacuum moving-bed reactor, a transported-bed reactor, and a
fixed-bed reactor.
4. The process either claim 1 or 2, wherein said pyrolysis reaction
is carried out in said reactor B selected from a group consisting
of an auger reactor, an ablative reactor, a bubbling fluidized bed
reactor, a circulating fluidized bed/transport reactor, a rotating
cone pyrolyzer, and a vacuum pyrolyzer.
5. The process either claim 1 or 2, wherein said torrefaction
reaction is carried out in the presence of a catalytic material
selected from a group consisting acid catalysts, solid base
catalysts, silica catalysts, silica-alumina catalysts, Group B
metal oxide catalysts, pyrolytic char and any combination
thereof.
6. The process either claim 1 or 2, wherein said torrefaction
reaction is carried out in the presence of a catalytic material
selected from a group consisting ZSM5, Hydrotalcite, Diatomite,
Kaolin, Ammonium Molybdate, pyrolytic char and any combination
thereof.
7. The process either claim 1 or 2, wherein said pyrolysis reaction
is carried out in the presence of a catalytic material selected
from a group consisting acid catalyst, solid base catalyst, silica
catalyst, silica-alumina catalyst, Group B metal oxide catalyst,
pyrolytic char and any combination thereof.
8. The process either claim 1 or 2, wherein said pyrolysis reaction
is carried out in the presence of a catalytic material selected
from a group consisting ZSM5, Hydrotalcite, Diatomite, Kaolin,
Ammonium Molybdate, pyrolytic char and any combination thereof.
9. The process of either claim 1 or 2, wherein said torrefaction
reaction is carried out in the absence of diatomic oxygen in an
inert gas atmosphere comprising nitrogen, argon, steam or carbon
oxide.
10. The process of either claim 1 or 2, wherein said torrefaction
reaction is carried out in a reducing gas atmosphere.
11. The process of claim 10, wherein said reducing gas atmosphere
comprises carbon monoxide.
12. The process of either claim 1 or 2, wherein said torrefaction
reaction is carried out with a reactant comprising hydrogen or
ammonia.
13. The process of either claim 1 or 2, wherein said biomass
feedstock is selected from the group consisting of, wood, paper,
crops, animal and plant fats, biological waste, algae and mixture
thereof.
14. The process of claim 1, wherein said torrefaction reaction
conditions includes a temperature ranging from 180.degree. C. to
350.degree. C., a pressure ranging from 0.1 psia to 500 psia, and a
residence time ranging from 1 min to 24 hours.
15. A pyrolysis oil produced by a method according to claim 1.
16. A pyrolysis oil produced by a method according to claim 2.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] None.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] None.
FIELD OF THE INVENTION
[0003] The present invention relates generally to the conversion of
biomass to fuel range hydrocarbons.
BACKGROUND OF THE INVENTION
[0004] Due to governmental legislation as mandated in the Renewable
Fuels Standards (RFS), the use of renewable energy sources is
becoming increasingly necessary to reduce emissions of carbon based
fuels and provide alternatives to petroleum based energy and
feedstock. One of the alternatives being explored is the use of
biomass. Biomass is any carbon containing material derived from
living or formerly living organisms, such as wood, wood waste,
crops, crop waste, waste, and animal waste.
[0005] Pyrolysis is the chemical decomposition of organic materials
by heating in the absence of oxygen or other reagents. Pyrolysis
can be used to convert biomass (such as lignocellulosic biomass)
into pyrolysis oil or so-called bio-oil. The bio-oils obtained by
pyrolysis of biomass or waste have received attention recently as
an alternative source of fuel.
[0006] Generally the pyrolysis of biomass produces four primary
products, namely water, "bio-oil," also known as "pyrolysis oil,"
char, and various gases (H.sub.2, CO, CO.sub.2, CH.sub.4, and other
light hydrocarbons) that do not condense, except under extreme
conditions. For exemplary purposes, the pyrolysis decomposition
products of wood from white spruce and poplar trees are shown in
Table 1.
TABLE-US-00001 TABLE 1 Source: Piskorz, J., et al. In Pyrolysis
Oils from Biomass, Soltes, E. J. Milne, T. A., White Eds., ACS
Symposium Series 376, 1988. Spruce Poplar Moisture content, wt %
7.0 3.3 Particle size, .mu.m (max) 1000 590 Temperature 500 497
Apparent residence time 0.65 0.48 Product Yields, wt %, m.f. Water
11.6 12.2 Gas 7.8 10.8 Bio-char 12.2 7.7 Bio-oil 66.5 65.7 Bio-oil
composition, wt %, m.f. Saccharides 3.3 2.4 Anhydrosugars 6.5 6.8
Aldehydes 10.1 14.0 Furans 0.35 -- Ketones 1.24 1.4 Alcohols 2.0
1.2 Carboxylic acids 11.0 8.5 Water-Soluble - Total Above 34.5 34.3
Pyrolytic Lignin 20.6 16.2 Unaccounted fraction 11.4 15.2
[0007] Fast pyrolysis is one method for the conversion of biomass
to bio-oil. Fast pyrolysis is the rapid thermal decomposition of
organic compounds in the absence of atmospheric or added oxygen to
produce liquids, char, and gas. Fast pyrolysis affords operation at
atmospheric pressure, moderate temperatures, and with low or no
water usage. Pyrolysis oil yields typically range from 50-75% mass
of input biomass and are heavily feedstock dependent.
[0008] The major advantage of these fuels is that these are
CO.sub.2 neutral and contain a very low fraction of bonded sulfur
and nitrogen. Thus, they contribute very little to the emission of
greenhouse gases or other regulated air pollutants.
[0009] There has been a considerable effort in the past to develop
pyrolysis processes for the conversion of biomass and waste to
liquids for the express purpose of producing renewable liquid fuels
suitable for use in boilers, gas turbines and diesel engines.
[0010] However, pyrolysis oil obtained from biomass fast pyrolysis
process is chemical complex compounds comprising generally a
mixture of water, light volatiles, and non-volatiles. They are in
general of relatively low quality. As fuels they have a number of
negative properties such as high acidity (lead to corrosion
problem), substantial water content (usually in the range of 15% to
30%), variable viscosity, low heating values (about half that of
the diesel fuel), low cetane number, etc. These negative properties
are related to the oxygenated compounds contained in bio-oils that
result in a 45% oxygen content. In general, the pyrolysis oil has
total acidity number (TAN) value of approximately 100. The desired
TAN value for transportation fuel is less than 10.
[0011] There has been a considerable effort in the past to address
the high TAN problem by post treatment or upgrading the pyrolysis
oils before they are used as a regular fuel. Most method
essentially involves the removal of oxygen. Particular attention
has been focused on hydrotreating using conventional petroleum
catalysts, for example, cobalt-molybdenum or nickel-molybdenum on
alumina to produce essentially oxygen-free naphthas. Since
pyrolysis liquids typically contain between 30 to 50 wt % of
oxygen, complete removal of oxygen requires a substantial
consumption of hydrogen which represents a major and prohibitive
cost.
[0012] Therefore, developing a new method or process for improving
quality of pyrolysis oil would be a significant contribution to the
art.
BRIEF SUMMARY OF THE DISCLOSURE
[0013] Generally speaking, this invention discloses a process for
producing high quality pyrolysis oil from biomass by utilizing a
torrefaction pretreatment step for biomass pyrolysis process
wherein the pretreatment step improves the quality of the pyrolysis
oil by reducing acidity.
[0014] The disclosed process comprises at least the following
steps: a) a step of subjecting a biomass feedstock to a thermal
treatment in a reactor A under a torrefaction reaction condition to
produce an torrefied biomass feedstock; and b) a step of pyrolyzing
the torrefied biomass feedstock in a reactor B under a pyrolysis
reaction condition to form a pyrolysis oil product.
[0015] The torrefaction reaction condition includes a temperature
ranging from 180.degree. C. to 350.degree. C., a pressure ranging
from atmospheric pressure to 500 psia, and a residence time ranging
from 1 minute to 24 hours. The pyrolysis reaction condition
includes a temperature ranging from 375.degree. C. to 700.degree.
C., a pressure ranging from vacuum conditions (0.1 psia) to 1000
psia., and a residence time ranging from 0.1 to 200 seconds. The
pyrolysis oil product according to the current invention has a TAN
number between 80 and 200.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] None.
DETAILED DESCRIPTION
[0017] Embodiments of the invention relate to a process to utilize
a torrefaction pretreatment step for biomass pyrolysis process.
This pretreatment improves the quality of the pyrolysis oil by
reducing acidity. The inventive process shows that as a
pretreatment to pyrolysis, resulting pyrolysis oil obtained from
torrefied biomass has approximately 25% lower acetic acid than that
from untorrefied biomass pyrolysis oil.
[0018] As used herein, the term "biomass" includes any renewable
source (living or formerly living), but does not include oil,
natural gas, and/or petroleum. Biomass thus includes but is not
limited to wood, paper, crops, animal and plant fats, biological
waste, algae, and the like.
[0019] According to one embodiment of the invention, there is
disclosed a step of subjecting a biomass feedstock to a thermal
treatment in a reactor under a torrefaction reaction condition to
produce a torrefied biomass feedstock.
[0020] Torrefaction consists of a slow heating of biomass feedstock
in an inert atmosphere to produce a solid with lower hemicellulose
content, higher energy density, nearly moisture free (<3 wt %),
and low resistance to fracture (brittle).
[0021] Any standard torrefaction reactor can be used to torrefy the
biomass feedstock. Exemplary reactor configurations include without
limitations augers reactor, ablative reactor, rotating cones
reactor, fluidized-bed reactor, entrained-flow reactor, vacuum
moving-bed reactor, transported-bed reactor, and fixed-bed
reactor.
[0022] Any standard torrefaction reaction condition can be used to
torrefy the biomass feedstock in the torrefaction reactor. A person
skilled in the art can readily select a combination of temperature,
pressure, and residence time that produces a torrefied product. In
one embodiment, the torrefaction reaction condition includes a
temperature ranging from 180.degree. C. to 350.degree. C., a
pressure ranging from atmospheric pressure to 500 psia, and a
residence time ranging from 1 minute to 24 hours. In another
embodiment, the torrefaction reaction condition includes a
temperature ranging from 220.degree. C. to 280.degree. C., a
pressure ranging from 11 psia to 30 psia, and a residence time
ranging from 5 to 20 minutes. In yet another alternative
embodiment, the torrefaction reaction conditions include a
temperature ranging from 180.degree. C. to 350.degree. C., a
pressure ranging from 0.1 psia to 500 psia, and a residence time
ranging from 1 minute to 24 hours.
[0023] A variety of catalysts may be used for torrefaction
reaction. In some embodiments, torrefaction is carried out in the
presence of a catalyst material selected from a group consisting
solid acid catalyst such as ZSM5, solid base catalyst such as
Hydrotalcite, silica catalyst such as Diatomite, silica-alumina
catalyst such as Kaolin, Group B metal oxide catalyst such as
Ammonium Molybdate, pyrolytic char and any combination thereof.
[0024] In some embodiments, the torrefaction reaction is carried
out in the absence of diatomic oxygen in an inert gas atmosphere
such as nitrogen, argon, steam, carbon oxides, etc. In some
embodiments, the torrefaction reaction is carried out in a reducing
gas atmosphere that comprises carbon monoxide. Also, torrefaction
may be carried out with other reactants such as hydrogen, ammonia,
etc.
[0025] The torrefied biomass according to various embodiments of
the invention may be added to a pyrolysis reactor for further
processing. In some embodiments, the torrefied biomass is pyrolyzed
in a pyrolysis reactor under pyrolysis reaction conditions to form
a pyrolysis oil product.
[0026] Pyrolysis, which is the thermal decomposition of a substance
into its elemental components and/or smaller molecules, is used in
various methods developed for producing hydrocarbons, including but
not limited to hydrocarbon fuels, from biomass. Pyrolysis requires
moderate temperatures, generally greater than about 325.degree. C.,
such that the feed material is sufficiently decomposed to produce
products which may be used as hydrocarbon building blocks.
[0027] Embodiments of the inventive process use any standard
pyrolysis reactor providing sufficient heat to pyrolyze torrefied
biomass feedstock, including without limitation, auger reactor,
ablative reactor, a bubbling fluidized bed reactor, circulating
fluidized beds/transport reactor, rotating cone pyrolyzer, vacuum
pyrolyzer, and the like.
[0028] Any standard pyrolysis reaction condition can be used to
pyrolyze the torrefied biomass feedstock in a pyrolysis reactor. A
person skilled in the art can readily select a combination of
temperature, pressure, and residence time that produces a pyrolyzed
product. In one embodiment, the pyrolysis reaction condition
includes a temperature ranging from 375.degree. C. to 700.degree.
C., a pressure ranging from vacuum condition to 1000 psig., and a
residence time ranging from 0.1 to 200 seconds. In another
embodiment, the pyrolysis reaction condition includes a temperature
ranging from 425.degree. C. to 525.degree. C., a pressure ranging
from atmospheric pressure to 300 psia., and a residence time
ranging from 0.5 to 2 seconds.
[0029] A variety of catalysts may be used for the pyrolysis
reaction. In one embodiment, the pyrolysis reaction is carried out
in the presence of a catalyst material selected from a group
consisting of solid acid catalyst such as ZSM5, solid base catalyst
such as Hydrotalcite, silica catalyst such as Diatomite,
silica-alumina catalyst such as Kaolin, Group B metal oxide
catalyst such as Ammonium Molybdate, pyrolytic char and any
combination thereof.
[0030] The pyrolysis oil product obtained according to some
embodiments of the present invention has a TAN number between 80
and 200. The pyrolysis oil product obtained according to some other
embodiments of the present invention has a TAN number between less
than 20 and 50.
[0031] The following examples of certain embodiments of the
invention are given. Each example is provided by way of explanation
of the invention, one of many embodiments of the invention, and the
following examples should not be read to limit, or define, the
scope of the invention.
Example 1
[0032] The comparison study of the process of torrefaction prior to
pyrolysis has been performed in a micropyrolysis unit. The
reactions were carried out at torrefaction temperatures ranging
from 179.degree. C. to 321.degree. C. and pyrolysis temperatures
ranging from 379.degree. C. to 521.degree. C. with no catalyst
loading. In addition, a wide variety of biomass was tested
including red oak, switchgrass, miscanthus, and corn stover
pellets. Comparative pyrolysis tests were run without the
torrefaction pretreatment at the same pyrolysis temperatures.
Results:
[0033] The experimental results indicating the reduction of acetic
acid in the pyrolysis product due to torrefaction are shown as
follows:
TABLE-US-00002 TABLE I Average Acetic Acid Yield. Torrefaction-
Pyrolysis Pyrolysis Reduction.sup.3 Yield.sup.1, Yield.sup.1,
Conc..sup.2, Yield.sup.1, Conc..sup.2, Biomass wt-% Conc..sup.2, %
wt-% % wt-% % Oak 8.76 5.38 6.29 4.40 28.2 18.1 Switchgrass 4.64
4.79 3.07 3.96 34.0 17.3 Miscanthus 3.75 6.25 2.35 4.41 37.2 29.4
Corn Stover 1.89 5.41 0.74 3.29 60.7 39.3 .sup.1Mass of acetic acid
over mass of biomass .sup.2Acetic acid peak area over total peak
area by GC/MS .sup.3Torrefaction-pyrolysis acetic acid level
relative to pyrolysis acetic acid level
[0034] The result above shows that the acetic acid concentration in
pyrolysis oil products was reduced by 18 to 39% with this
pretreatment than that from un-torrefied biomass. The resulting
pyrolysis oil would have a similar reduction in TAN (total acid
number) value as .about.80% of the TAN is due to acetic acid in
pyrolysis oils.
Discussion:
[0035] As discussed above, the pyrolysis oil obtained from biomass
fast pyrolysis process is of relatively low quality. In general,
pyrolysis oil has TAN value of approximately 100. The desired TAN
value for transportation fuel is less than 10.
[0036] The results above shows that using torrefied biomass as a
pretreated feed for pyrolysis helps reduce TAN (total acid number)
of the pyrolysis oil product. The pretreatment by torrefaction
according to the current invention helps to significantly reduce
the TAN value of the pyrolysis oil product by 25%. This is mainly
attributed to the release of acetic acid in the torrefaction
step.
[0037] The step of pretreatment of torrefaction can be easily
integrated with the pyrolysis step. The pretreatment step improves
the quality of the feed quality of pyrolysis step and therefore
results in higher quality of pyrolysis oil product including low
TAN value. In addition, such integrated process reduces the
operating cost and capital investment of post treatment
process.
[0038] It should be noted that, as used in this specification and
the appended claims, the singular forms "a," "an," and "the"
include plural references unless the content clearly dictates
otherwise. Thus, for example, reference to a composition containing
"a compound" includes a mixture of two or more compounds. It should
also be noted that the term "or" is generally employed in its sense
including "and/or" unless the content clearly dictates otherwise.
It should also be noted that, as used in this specification and the
appended claims, the phrase "configured" describes a system,
apparatus, or other structure that is constructed or configured to
perform a particular task or adopt a particular configuration. The
phrase "configured" can be used interchangeably with other similar
phrases such as arranged and configured, constructed and arranged,
constructed, manufactured and arranged, and the like.
[0039] Although the systems and processes described herein have
been described in detail, it should be understood that various
changes, substitutions, and alterations can be made without
departing from the spirit and scope of the invention as defined by
the following claims. Those skilled in the art may be able to study
the preferred embodiments and identify other ways to practice the
invention that are not exactly as described herein. It is the
intent of the inventors that variations and equivalents of the
invention are within the scope of the claims, while the
description, abstract and drawings are not to be used to limit the
scope of the invention. The invention is specifically intended to
be as broad as the claims below and their equivalents. In closing,
it should be noted that each and every claim below is hereby
incorporated into this detailed description or specification as an
additional embodiments of the present invention.
* * * * *