U.S. patent application number 12/646203 was filed with the patent office on 2011-06-23 for low water biomass-derived pyrolysis oil and processes for preparing the same.
Invention is credited to Timothy A. Brandvold, Stanley J. Frey.
Application Number | 20110146140 12/646203 |
Document ID | / |
Family ID | 44149101 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110146140 |
Kind Code |
A1 |
Brandvold; Timothy A. ; et
al. |
June 23, 2011 |
LOW WATER BIOMASS-DERIVED PYROLYSIS OIL AND PROCESSES FOR PREPARING
THE SAME
Abstract
Low water-containing biomass-derived pyrolysis oils and
processes for preparing them are provided. Water-containing
biomass-derived pyrolysis oil is distilled in the presence of an
azeotrope-forming liquid to form an azeotrope. The azeotrope is
removed at or above the boiling point of the azeotrope and low
water biomass-derived pyrolysis oil is obtained.
Inventors: |
Brandvold; Timothy A.;
(Arlington Heights, IL) ; Frey; Stanley J.;
(Palatine, IL) |
Family ID: |
44149101 |
Appl. No.: |
12/646203 |
Filed: |
December 23, 2009 |
Current U.S.
Class: |
44/309 |
Current CPC
Class: |
B01D 3/36 20130101; C10L
1/02 20130101 |
Class at
Publication: |
44/309 |
International
Class: |
C10L 1/18 20060101
C10L001/18 |
Claims
1. A process for reducing water in a water-containing
biomass-derived pyrolysis oil comprising the steps of: distilling
the water-containing biomass-derived pyrolysis oil in the presence
of an azeotrope-forming liquid to form an azeotrope; and removing
the azeotrope.
2. The process of claim 1, wherein the step of distilling the
water-containing biomass-derived pyrolysis oil comprises selecting
the azeotrope-forming liquid from the group consisting of toluene,
ethanol, acetone, 2-propanol, cyclohexane, 2-butanone, octane,
benzene, and ethyl acetate.
3. The process of claim 2, wherein the step of distilling the
water-containing biomass-derived pyrolysis oil comprises forming
the azeotrope selected from the group consisting of ethanol/water,
toluene/water, acetone/water, 2-propanol/water, cyclohexane/water,
2-butanone/water, octane/water, ethanol/toluene/water,
1-butanol/octane/water, benzene/2-propanol/water,
ethanol/2-butanone/water, and ethanol/ethyl acetate/water.
4. The process of claim 1, wherein the step of distilling the
water-containing biomass-derived pyrolysis oil comprises heating
the water-containing biomass-derived pyrolysis oil to a minimum
distillation temperature of the boiling point of the azeotrope at a
given atmospheric pressure.
5. The process of claim 1, wherein the step of distilling the
water-containing biomass-derived pyrolysis oil comprises adding the
azeotrope-forming liquid to the water-containing biomass-derived
pyrolysis oil, a minimum amount of the azeotrope-forming liquid to
be added (in kilograms) calculated according to the following
calculations: x = weight ratio of azeotrope - forming liquid to
water in azeotrope mass ( in kilograms ) of water to be removed
from biomass - derived pyrolysis oil Minimum amount of azeotrope -
forming liquid to be added ( in kilograms ) to the starting oil
##EQU00002## wherein the mass (in kg) of water to be
removed=M.sub.f*([H.sub.2O].sub.i-[H.sub.2O].sub.f)/(1-[H.sub.2O].sub.f);
and wherein: M.sub.f=mass of water-containing biomass-derived
pyrolysis oil (in kilograms); and [H.sub.2O].sub.i and
[H.sub.2O].sub.f=water concentration in grams of water per gram of
oil of the initial (water-containing biomass-derived pyrolysis oil)
and final pyrolysis oil (low water biomass-derived pyrolysis oil)
respectively.
6. The process of claim 5, wherein the step of distilling the
water-containing biomass-derived pyrolysis oil further comprises
adding more of the azeotrope-forming liquid to the water-containing
biomass-derived pyrolysis oil than the minimum amount.
7. The process of claim 1, wherein the step of distilling the
water-containing biomass-derived pyrolysis oil in the presence of
an azeotrope-forming liquid comprises distilling the
water-containing biomass-derived pyrolysis oil in the presence of a
first azeotrope-forming liquid and a second azeotrope-forming
liquid.
8. A process for preparing low water biomass-derived pyrolysis oil
comprising the steps of: introducing biomass-derived pyrolysis oil
and an azeotrope-forming liquid into a distillation apparatus
maintained at a temperature sufficient to form an azeotrope, the
temperature being at least the minimum boiling point of the
azeotrope; removing the azeotrope from the distillation apparatus
at or above the boiling point of the azeotrope; and removing low
water biomass-derived pyrolysis oil from the distillation
apparatus.
9. The process of claim 8, wherein the step of introducing the
biomass-derived pyrolysis oil and the azeotrope-forming liquid
comprises selecting the azeotrope-forming liquid from the group
consisting of toluene, ethanol, acetone, 2-propanol, cyclohexane,
2-butanone, octane, benzene, and ethyl acetate.
10. The process of claim 9, wherein the step of removing the
azeotrope comprises removing the azeotrope selected from the group
consisting of ethanol/water, toluene/water, acetone/water,
2-propanol/water, cyclohexane/water, 2-butanone/water,
octane/water, ethanol/toluene/water, 1-butanol/octane/water,
benzene/2-propanol/water, ethanol/2-butanone/water, and
ethanol/ethyl acetate/water.
11. The process of claim 8, wherein the step of introducing
biomass-derived pyrolysis oil and the azeotrope-forming liquid
comprises the step of adding the azeotrope-forming liquid to the
biomass-derived pyrolysis oil, the distillation apparatus, or a
combination thereof.
12. The process of claim 11, wherein the step of adding the
azeotrope-forming liquid comprises adding the azeotrope-forming
liquid in at least an amount calculated according to the following
calculations: x = weight ratio of azeotrope - forming liquid to
water in azeotrope mass ( in kilograms ) of water to be removed
from biomass - derived pyrolysis oil Minimum amount of azeotrope -
forming liquid to be added ( in kilograms ) to the starting oil
##EQU00003## wherein the mass (in kg) of water to be
removed=M.sub.f*([H.sub.2O].sub.i-[H.sub.2O].sub.f)/(1-[H.sub.2O].sub.f);
and wherein: M.sub.f=mass of water-containing biomass-derived
pyrolysis oil (in kilograms); and [H.sub.2O].sub.i and
[H.sub.2O].sub.f=water concentration in grams of water per gram of
oil of the initial (water-containing biomass-derived pyrolysis oil)
and final pyrolysis oil (low water biomass-derived pyrolysis oil)
respectively.
13. A low water biomass-derived pyrolysis oil produced by a process
which comprises the steps of: distilling water-containing
biomass-derived pyrolysis oil in the presence of an
azeotrope-forming liquid to form an azeotrope; and removing the
azeotrope and obtaining low water biomass-derived pyrolysis oil,
the low water biomass-derived pyrolysis oil having a water content
less than the water-containing biomass-derived pyrolysis oil and
containing residual azeotrope-forming liquid.
14. The low water biomass-derived pyrolysis oil of claim 13,
wherein the azeotrope-forming liquid is selected from the group
consisting of toluene, ethanol, acetone, 2-propanol, cyclohexane,
2-butanone, octane, benzene, and ethyl acetate.
15. The low water biomass-derived pyrolysis oil of claim 14,
wherein the azeotrope is selected from the group consisting of
ethanol/water, toluene/water, acetone/water, 2-propanol/water,
cyclohexane/water, 2-butanone/water, octane/water,
ethanol/toluene/water, 1-butanol/octane/water,
benzene/2-propanol/water, ethanol/2-butanone/water, and
ethanol/ethyl acetate/water.
16. The low water biomass-derived pyrolysis oil of claim 13,
wherein the azeotrope-forming liquid is present in at least an
amount calculated according to the following calculations: x =
weight ratio of azeotrope - forming liquid to water in azeotrope
mass ( in kilograms ) of water to be removed from biomass - derived
pyrolysis oil Minimum amount of azeotrope - forming liquid present
( in kilograms ) in the starting oil ##EQU00004## wherein the mass
(in kg) of water to be
removed=M.sub.f*([H.sub.2O].sub.i-[H.sub.2O].sub.f)/(1-[H.sub.2O].sub.f);
and wherein: M.sub.f=mass of water-containing biomass-derived
pyrolysis oil (in kilograms); and [H.sub.2O].sub.i and
[H.sub.2O].sub.f=water concentration in grams of water per gram of
oil of the initial (water-containing biomass-derived pyrolysis oil)
and final pyrolysis oil (low water biomass-derived pyrolysis oil)
respectively.
17. The low water biomass-derived pyrolysis oil of claim 13,
wherein the azeotrope is removed at or above the boiling point of
the azeotrope at a given atmospheric pressure.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to co-pending U.S. application
Ser. No. ______ entitled "LOW METAL, LOW WATER BIOMASS-DERIVED
PYROLYSIS OILS AND METHODS FOR PRODUCING THE SAME", and U.S.
application Ser. No. ______ entitled "METHODS FOR REGENERATING
ACIDIC ION-EXCHANGE RESINS AND REUSING REGENERANTS IN SUCH
METHODS", filed concurrently herewith on ______, and which are
incorporated by reference herein in their entirety.
FIELD OF THE INVENTION
[0002] The present invention generally relates to biofuels and
processes for preparing biofuels, and more particularly relates to
low water biomass-derived pyrolysis oil and processes for producing
the same.
DESCRIPTION OF RELATED ART
[0003] Fast pyrolysis is a process during which organic biomass
materials, such as wood waste, agricultural waste, etc., are
rapidly heated to about 450.degree. C. to about 600.degree. C. in
the absence of air using a process reactor. Under these conditions,
organic vapors, pyrolysis gases and ash (char) are produced. The
vapors are condensed to biomass-derived pyrolysis oil.
Biomass-derived pyrolysis oil is a complex, highly oxygenated
organic liquid typically containing about 20-30% by weight water
with high acidity (TAN>150).
[0004] Biomass-derived pyrolysis oil can be burned directly as fuel
for certain boiler and furnace applications. Biomass-derived
pyrolysis oil can also serve as a potential feedstock in catalytic
processes for the production of fuel in petroleum refineries.
Biomass-derived pyrolysis oil has the potential to replace up to
60% of transportation fuels, thereby reducing the dependency on
conventional petroleum and reducing its environmental impact.
[0005] Unfortunately, the high water content of the biomass-derived
pyrolysis oil increases the storage instability of the oil.
Biomass-derived pyrolysis oil may often be stored in tanks or the
like for long periods of time. The high water content is correlated
with increases in viscosity, phase separation and/or solids
formation during such storage. As-produced biomass-derived
pyrolysis oil cannot be simply distilled to completely remove
water, as phase separation and/or solids formation result as
volatiles are removed. If as-produced biomass-pyrolysis oil is
heated to elevated temperatures, some volatiles may vaporize
initially, but the majority of the oil solidifies and/or chars.
[0006] Accordingly, it is desirable to provide low water
biomass-derived pyrolysis oil having substantially increased
storage stability and processes for producing the same.
Furthermore, other desirable features and characteristics of the
present invention will become apparent from the subsequent detailed
description of the invention and the appended claims, taken in
conjunction with the accompanying drawings and this background of
the invention.
SUMMARY OF THE INVENTION
[0007] Processes are provided for reducing water in a
water-containing biomass-derived pyrolysis oil. In accordance with
one exemplary embodiment, a process for reducing water comprises
distilling the water-containing biomass-derived pyrolysis oil in
the presence of an azeotrope-forming liquid to form an azeotrope
and removing the azeotrope.
[0008] Processes are provided for preparing low water
biomass-derived pyrolysis oil in accordance with yet another
exemplary embodiment of the present invention. The process
comprises the steps of introducing biomass-derived pyrolysis oil
and an azeotrope-forming liquid into a distillation apparatus
maintained at a temperature sufficient to form an azeotrope. The
temperature is at least the minimum boiling point of the azeotrope.
The azeotrope is removed from the distillation apparatus and the
low water biomass-derived pyrolysis oil is removed from the
distillation apparatus.
[0009] Low water biomass-derived pyrolysis oils produced by the
processes are also provided in accordance with another exemplary
embodiment of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention will hereinafter be described in
conjunction with the following drawing figures, wherein like
numerals denote like elements, and wherein:
[0011] FIG. 1 is a flow chart of a process for reducing the water
content of biomass-derived pyrolysis oil to produce low water
biomass-derived pyrolysis oils according to exemplary embodiments
of the present invention; and
[0012] FIG. 2 is a schematic diagram of an apparatus for performing
the process of FIG. 1 for reducing the water content of
water-containing biomass-derived pyrolysis oil according to
exemplary embodiments of the present invention.
DETAILED DESCRIPTION
[0013] The following detailed description of the invention is
merely exemplary in nature and is not intended to limit the
invention or the application and uses of the invention.
Furthermore, there is no intention to be bound by any theory
presented in the preceding background of the invention or the
following detailed description of the invention.
[0014] In accordance with exemplary embodiments of the present
invention, the water content in biomass-derived pyrolysis oil is
reduced by azeotropic distillation. One or more azeotrope-forming
liquids are added to the biomass-derived pyrolysis oil such that an
azeotrope with water forms upon distillation. As used herein, an
"azeotrope" is a mixture of two or more substances whose liquid and
gaseous forms have the same composition (at a certain pressure).
The azeotrope is removed from the biomass-derived pyrolysis oil
leaving low-water biomass-derived pyrolysis oil. It should be
appreciated that while treated oil is generally described herein as
a "low water biomass-derived pyrolysis oil", "low water
biomass-derived pyrolysis oil" generally includes any treated oil
having a lower weight percent (wt %) of water than in the starting
biomass-derived pyrolysis oil as a result of the azeotropic
distillation according to exemplary embodiments of the present
invention. The wt % water in the starting and low water
biomass-derived pyrolysis oils may be measured, for example, by
Karl Fischer Reagent Titration Method (ASTM D1364) as known to one
skilled in the art.
[0015] As shown in FIGS. 1 and 2, the present invention is directed
to a process 100 for reducing the water content of biomass-derived
pyrolysis oil to prepare low water biomass-derived pyrolysis oil.
The process 100 includes the step of providing biomass-derived
pyrolysis oil 112 (step 102). The biomass-derived pyrolysis oil 112
is provided from a source such as a feed tank (not shown) or other
source operative to provide such biomass-derived pyrolysis oil. The
biomass-derived pyrolysis oil composition is somewhat dependent on
feedstock and processing variables. The weight percent (wt %) water
in the biomass-derived pyrolysis oil generally ranges from about 20
to about 30%. Such biomass-derived pyrolysis oil is available from,
for example, Ensyn Technologies Inc., Ontario, Canada.
[0016] The biomass-derived pyrolysis oil may be produced, for
example, from fast pyrolysis of wood biomass. However, the
invention is not so limited. Virtually any form of biomass can be
considered for pyrolysis to produce biomass-derived pyrolysis oil.
In addition to wood, biomass-derived pyrolysis oil may be derived
from biomass material such as agricultural wastes/residues, nuts
and seeds, algae, grasses, forestry residues, cellulose and lignin
or the like. The biomass-derived pyrolysis oil may be obtained by
different modes of pyrolysis, such as fast pyrolysis, vacuum
pyrolysis, catalytic pyrolysis, and slow pyrolysis (also known as
carbonization), under different processing parameters.
[0017] Process 100 continues with the step of distilling the
biomass-derived pyrolysis oil 112 by introducing the
biomass-derived pyrolysis oil and one or more azeotrope-forming
liquids ("Azeotrope Liquid A" and/or "Azeotrope Liquid B") 114 and
116 into a distillation apparatus 118 maintained at an effective
temperature to form an azeotrope 120 (step 104). The minimum
effective temperature is the boiling temperature of the azeotrope
to be formed, as shown below in Table 1. The biomass-derived
pyrolysis oil may be introduced into the distillation apparatus as
a single stream as shown or as more than one stream. The added
azeotrope-forming liquid(s) 114 and 116 utilized to form the
azeotrope with water (from the water-containing biomass-derived
pyrolysis oil) during distillation may be added to the distillation
apparatus as a separate stream or streams, in which case the
azeotrope-forming liquid(s) should be added below the lowest feed
point of the starting biomass-derived pyrolysis oil 112.
Alternately, it may be mixed with the biomass-derived pyrolysis oil
stream(s) before it is fed to the distillation apparatus 118, or a
combination of adding the azeotrope-forming liquid(s) to both the
distillation apparatus 118 and the starting biomass-derived
pyrolysis oil may be used. If two azeotrope-forming liquids 114 and
116 are added to the biomass-derived pyrolysis oil 112, a ternary
azeotrope with the water is formed. To form binary azeotropes with
water, one azeotrope-forming liquid may be added to the
biomass-derived pyrolysis oil.
[0018] Effective azeotrope-forming liquids for preparing low water
biomass-derived pyrolysis oil include toluene, ethanol, acetone,
2-propanol, cyclohexane, 2-butanone, octane, benzene, ethyl
acetate, and combinations thereof. Exemplary suitable azeotropes
formed during process 100 include binary azeotropes such as
ethanol/water, toluene/water, acetone/water, 2-propanol/water,
cyclohexane/water, 2-butanone/water, and octane/water and ternary
azeotropes such as ethanol/toluene/water, 1-butanol/octane/water,
benzene/2-propanol/water, ethanol/2-butanone/water, and
ethanol/ethyl acetate/water. The weight ratio and boiling point of
each of these azeotropes at atmospheric pressure is shown below in
Table 1:
TABLE-US-00001 TABLE 1 Weight Ratio Boiling Point, Azeotrope (1
atm) .degree. C. (1 atm) Ethanol/Water 96:4 78 Toluene/Water 80:20
85 Acetone/Water 88:12 56 2-propanol/Water 88:12 80
Cyclohexane/Water 92:8 70 2-butanone/Water 89:11 73 Octane/Water
72:26 90 Ethanol/Toluene/Water 37:51:12 74 1-butanol/octane/Water
15:25:60 86 Benzene/2-propanol/Water 72:20:8 66
Ethanol/2-butanone/Water 14:75:11 73 Ethanol/ethyl acetate/Water
8:83:9 70
Source: Gorden, Arnold J.; Ford Richard A. The Chemist's Companion:
A Handbook of Practical Data Techniques and References. 1972; John
Wiley and Sons (New York); pp. 24-30.
[0019] Azeotrope selection is driven by the amount and cost of the
azeotrope-forming liquids, the desired boiling temperature, and the
compatibility of the azeotrope-forming liquid with the low water
biomass-derived pyrolysis oil. "Compatibility" as used herein means
that the azeotrope-forming liquid is co-soluble with the
biomass-derived pyrolysis oil, i.e., there is no phase separation
upon mixing of the biomass-derived pyrolysis oil and the
azeotrope-forming liquid(s). While certain azeotrope-forming
liquids and azeotropes have been identified, the present invention
is not so limited. Other azeotrope-forming liquids and azeotropes
may be used if they form an azeotrope with water alone or with
water in combination with other azeotrope-forming liquids.
[0020] The amount of azeotrope-forming liquid(s) and the minimum
temperatures required for water removal depend on the desired level
of water reduction and the specific azeotrope to be used. For
example, the minimum amount of the azeotrope-forming liquid(s)
added to the starting biomass-derived pyrolysis oil subjected to
the azeotropic distillation may be determined based on the wt % of
water in the biomass-derived pyrolysis oil (the "starting oil") and
the desired wt % water in the low water biomass-derived pyrolysis
oil (the "target oil"). The difference between these two numbers is
the wt % of water that must be removed. The wt % of water that must
be removed multiplied by the weight of the biomass-derived
pyrolysis oil provides the weight of the water that must be removed
from the starting oil to reach the desired wt % water in the target
oil. The weight ratios of the water and azeotrope-forming liquid in
the azeotrope can be used to calculate the minimum amount of each
of the azeotrope-forming liquids to be added (in kilograms) to the
starting oil according to the following calculations:
x = weight ratio of azeotrope - forming liquid to water in
azeotrope mass ( in kilograms ) of water to be removed from biomass
- derived pyrolysis oil Minimum amount of azeotrope - forming
liquid to be added ( in kilograms ) to the starting oil
##EQU00001##
The mass (in kg) of water to be
removed=M.sub.f*([H.sub.2O].sub.i-[H.sub.2O].sub.f)/(1-[H.sub.2O].sub.f).
wherein: M.sub.f=mass of water-containing biomass-derived pyrolysis
oil (in kilograms); and [H.sub.2O].sub.i and [H.sub.2O].sub.f=water
concentration in grams of water per gram of oil of the initial
(water-containing biomass-derived pyrolysis oil) and final
pyrolysis oil (low water biomass-derived pyrolysis oil)
respectively.
[0021] For example, where 1 kg of water-containing biomass-derived
pyrolysis oil ("starting oil) contains 25 wt % water as determined,
for example, by Karl Fischer titrations, i.e., 0.250 kg, and the
desired water content of the low water biomass-derived pyrolysis
oil ("target oil") contains 15 wt % water, the water to be
removed=1 kg*(0.25-0.15)/(1-0.15)=0.118 kg water. To form an
ethanol/toluene/water azeotrope having a weight ratio of 37:51:12
as identified in Table 1 above, the amount of ethanol and toluene
to be added to 1 kg of water-containing biomass-derived pyrolysis
oil is calculated as follows:
Ethanol to be added=37/12.times.0.118 kg=about 0.364 kg
Toluene to be added=51/12.times.0.118 kg=about 0.501 kg.
[0022] While the above calculations provide the minimum amount of
the one or more azeotrope-forming liquids to be added to the
starting oil, in practice, an excess amount of the one or more of
the azeotrope-forming liquids is added to drive the water reduction
and maintain phase homogeneity. The one or more azeotrope-forming
liquid(s) to be added in excess is selected based on compatibility
with the target oil as well as the relative costs of the
azeotrope-forming liquids. The amount to be added in excess is
determined experimentally.
[0023] The temperature in the distillation apparatus 118 is
maintained at least at the boiling temperature of the selected
azeotrope. The temperature may be increased above the minimum
boiling temperature to increase the distillation rate. However, the
temperature in the distillation apparatus preferably is kept at
least at the boiling temperature of the selected azeotrope but as
low as possible to remove water (normal boiling point=100.degree.
C.) while also avoiding solids formation. Heat (not shown) is
supplied to the distillation apparatus by any conventional means.
The temperatures in the top and bottom of the distillation
apparatus and where the feed stream enters the distillation
apparatus may be different. Depending on the distillation
apparatus, there may also be a temperature gradient in the
distillation apparatus in which the temperature is lower at the top
and higher at the bottom thereof. However, such temperature
differences are not required.
[0024] The pressure of the azeotrope is typically defined at 1
atmosphere. Alternate pressures (0.1 atm (sub atmospheric) to about
10 atmospheres (superatmospheric)) may be used but the azeotrope
composition may need to be adjusted by adding more or less of the
azeotrope-forming liquid(s). Absolute pressures of the vapor above
the boiling liquid near 1 atmosphere, about 0.8 to about 1.2
atmosphere, are preferred. The pressure is maintained by
application of a vacuum (for less than 1 atm) or use of a back
pressure regulating device (for greater than 1 atm). Process 100
continues with the step of removing the azeotrope 120 after its
formation (step 106). The azeotrope is removed as overhead vapors
from a top portion of the distillation apparatus 118.
[0025] Low water biomass-derived pyrolysis oil 124 is removed from
a bottom portion of the distillation apparatus (step 108). The
distilling step 104 may be repeated with the low water
biomass-derived pyrolysis oil to further reduce the water content,
as illustrated by dotted lines in FIGS. 1 and 2. The low water
biomass-derived pyrolysis oil may then be sent for further
processing into biofuel.
[0026] The resultant low water biomass-derived pyrolysis oil 124 is
of a single phase, is substantially storage-stable, and has a
higher energy density than the starting biomass-derived pyrolysis
oil 112. Higher energy density means that the low water
biomass-derived pyrolysis oil has an increased heat of combustion.
Low water biomass-derived pyrolysis oil having as low as about 3 to
about 4 wt % by weight water can be produced with increased thermal
and phase stability from biomass-derived pyrolysis oil having 20 to
30% by weight water.
[0027] The low water biomass-derived pyrolysis oil may include
residual azeotrope-forming liquid(s). Such residual
azeotrope-forming liquid(s) in the low water biomass-derived
pyrolysis oil help to improve the flow properties, energy density,
and may help the storage stability of the low water biomass-derived
pyrolysis oil. It is known, for example, that the addition of
ethanol to biomass-derived pyrolysis oil helps to keep the oil
phase stable during storage.
[0028] In addition, if the one or more azeotrope-forming liquids
are alcohols, reaction with some fraction of carboxylic acids that
may be in the biomass-derived pyrolysis oil may occur to form
esters and reaction of aldehydes and ketones (implicated in
solidification reactions) in the biomass-derived pyrolysis oil may
form acetals and ketals. This may result in reduced acidity in the
low water biomass-derived pyrolysis oil.
[0029] The present invention is further described in detail through
the following examples. However, the scope of the present invention
is by no means restricted or limited by the examples, which only
have an illustrative purpose.
EXAMPLE
[0030] A mixture of biomass-derived pyrolysis oil (123 g, starting
water content about 33 wt %), toluene (160 g) and ethanol (246 g)
was placed in a rotary evaporator and heated to 90.degree. C.
Volatiles were collected and both overhead vapors (348 g) and
distillation apparatus remnants (185 g) (i.e., low water
biomass-derived pyrolysis oil) were characterized. The distillate
composition (excluding water) was >99+% toluene and ethanol (as
determined by gas chromatography) with little or no biomass-derived
pyrolysis oil mass loss to overhead vapors. 96% of the toluene and
63% of ethanol was recovered in the distillate. The resultant
bottoms product (i.e., distillation apparatus remnants) was low
water biomass-derived pyrolysis oil having about 6.7 wt % water.
Thus, 185 g of low water biomass-derived pyrolysis oil with 6.7 wt
% water=12.4 g of water. The starting biomass-derived pyrolysis oil
(132 g, 33% water) had 43.6 g water. Thus, 43.6-12.4/43.6=71.6% of
the water was removed from the starting biomass-derived pyrolysis
oil. The acid number of the bottoms product was reduced slightly
(from about 186 to >145 mg KOH/g), but this may be a dilution
effect as substantial ethanol remained in the distillation
apparatus. The distilling step was then repeated with the low water
biomass-derived pyrolysis oil to further reduce the water content
to about 3 to about 4 wt %.
[0031] From the foregoing, it is to be appreciated that the low
water biomass-derived pyrolysis oil is a single phase liquid which
exhibits greater storage stability and higher energy density. The
low water biomass-derived pyrolysis oil is thus more suitable for
use as a biofuel than the starting biomass-derived pyrolysis
oil.
[0032] While at least one exemplary embodiment has been presented
in the foregoing detailed description of the invention, it should
be appreciated that a vast number of variations exist. It should
also be appreciated that the exemplary embodiment or exemplary
embodiments are only examples, and are not intended to limit the
scope, applicability, or configuration of the invention in any way.
Rather, the foregoing detailed description will provide those
skilled in the art with a convenient road map for implementing an
exemplary embodiment of the invention, it being understood that
various changes may be made in the function and arrangement of
elements described in an exemplary embodiment without departing
from the scope of the invention as set forth in the appended claims
and their legal equivalents.
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