U.S. patent application number 15/386069 was filed with the patent office on 2017-06-22 for process for conversion of a cellulosic material.
The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Andries Quirin Maria BOON, Jean Paul Andre Marie Joseph Ghislain LANGE, Joseph Broun POWELL.
Application Number | 20170175018 15/386069 |
Document ID | / |
Family ID | 57758809 |
Filed Date | 2017-06-22 |
United States Patent
Application |
20170175018 |
Kind Code |
A1 |
LANGE; Jean Paul Andre Marie Joseph
Ghislain ; et al. |
June 22, 2017 |
PROCESS FOR CONVERSION OF A CELLULOSIC MATERIAL
Abstract
A process for the high temperature conversion of a cellulosic
material into a bio-oil, wherein, under hydrogen atmosphere and in
the presence of a catalyst, the cellulosic material is contacted in
a reaction vessel with a liquid solvent, wherein water is present
from 5% up to 80 wt %, based on the total amount of cellulosic
material and liquid solvent present in the vessel, at an a
controlled operating pressure of from equal to or more than 2.0 MPa
to equal to or less than 13.0 MPa, wherein the partial hydrogen
pressure contributes from equal to or more than 1.0 MPa to equal to
or less than 6.0 MPa, and the total vapour pressure being lower
than the autogenous pressure at the operating temperature and
contributing in the range of from equal to or more than 1.0 MPa to
equal to or less than 7.0 MPa, to produce a product mixture
comprising bio-oil.
Inventors: |
LANGE; Jean Paul Andre Marie Joseph
Ghislain; (Amsterdam, NL) ; POWELL; Joseph Broun;
(Houston, TX) ; BOON; Andries Quirin Maria;
(Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
Houston |
TX |
US |
|
|
Family ID: |
57758809 |
Appl. No.: |
15/386069 |
Filed: |
December 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62270063 |
Dec 21, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 1/065 20130101;
C10G 2300/44 20130101; C10G 2300/1014 20130101; C10G 1/083
20130101; Y02P 30/20 20151101; C10G 2300/4012 20130101; C10L
2200/0469 20130101; C10L 1/02 20130101 |
International
Class: |
C10L 1/02 20060101
C10L001/02 |
Claims
1. A process for the high temperature conversion of a cellulosic
material into a bio-oil, wherein, under hydrogen atmosphere and in
the presence of a catalyst, the cellulosic material is contacted in
a reaction vessel with a liquid solvent, wherein water is present
from 5% up to 80 wt %, based on the total amount of cellulosic
material and liquid solvent present in the vessel, at an operating
temperature in the range from equal to or more than 180.degree. C.
to equal to or less than 300.degree. C., and at a controlled
operating pressure of from equal to or more than 2.0 MPa to equal
to or less than 13.0 MPa, wherein the partial hydrogen pressure
contributes from equal to or more than 1.0 MPa to equal to or less
than 6.0 MPa, and the total vapour pressure being lower than the
autogenous pressure at the operating temperature and contributing
in the range of from equal to or more than 1.0 MPa to equal to or
less than 7.0 MPa, to produce a product mixture comprising
bio-oil.
2. The process of claim 1 wherein the operating pressure is from
equal to or more than 3.5 MPa, equal to or more than 4.2 MPa, to
equal to or less than 11.0 MPa, preferably equal to or less than
10.0 MPa, wherein the partial hydrogen pressure contributes
respectively from equal to or more than 1.0 MPa, to equal to or
less than 5.0 MPa, and wherein the total vapour pressure
contributes respectively in the range from equal to or more than
2.0 MPa, to equal to or less than 6.0 MPa.
3. The process of claim 1 wherein the reaction vessel is provided
with a pressure control system that opens a pressurization valve
and shuts it once the internal pressure has reached a certain
setpoint in the desired operating pressure range.
4. The process of claim 1 wherein the reaction vessel is equipped
with an open gas restriction outlet that leads to a compartment of
low but controlled pressure.
5. The process of claim 1 wherein the cellulosic material comprises
from 2 to 50 wt % of water based on the total amount of cellulosic
material, when introduced into the reaction vessel.
6. The process of claim 1 wherein the catalyst is a sulfided
catalyst comprising cobalt and molybdenum, optionally comprising a
promoter.
7. The process of claim 1 wherein liquid solvent has a vapour
pressure at the operating temperature that is lower than the
operating pressure.
8. The process of claim 7 wherein liquid solvent is liquid at a
temperature in the range from equal to or more than 180.degree. C.
to equal to or less than 300.degree. C. at a pressure of 0.1
MPa.
9. The process of claim 1 wherein the liquid solvent is an organic
solvent.
10. The process of claim 9 wherein the organic solvent comprises
one or more carboxylic acids.
11. The process of claim 9 wherein the organic solvent comprises
paraffinic compounds, naphthenic compounds, olefinic compounds
and/or aromatic compounds.
12. The process of claim 9 wherein the organic solvent comprises at
least one phenolic group, optionally substituted with side
groups.
13. The process of claim 1 wherein the process further comprises
recycling a part of the product mixture having a vapour pressure at
the operating temperature that is lower than the operating
pressure, to be used as part of the liquid solvent.
14. The process of claim 1 wherein the process further comprises a
subsequent step wherein the product mixture is separated into a
light fraction comprising compounds having a molecular weight of
less than 100 grams per mol; a middle fraction comprising compounds
having a molecular weight in the range from equal to or more than
100 grams per mol to equal to or less than 1,000 grams per mol; and
a heavy fraction comprising compounds having a molecular weight of
more than 1,000 grams per mol.
15. The process of claim 14 wherein at least 30 wt % of the liquid
solvent used in the conversion process consists of recycled product
mixture middle fraction.
16. The process of claim 2 wherein the operating pressure is from
equal to or more than 4.2 MPa, to equal to or less than 10.0 MPa.
Description
[0001] The present application claims the benefit of pending U.S.
Provisional Application Ser. No. 62/270,063, filed 21 Dec. 2015,
the entire disclosure of which is hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] The invention relates to a process for conversion of a
cellulosic material and use of the products produced in such a
process.
BACKGROUND TO THE INVENTION
[0003] With the diminishing supply of crude mineral oil, use of
renewable energy sources is becoming increasingly important for the
production of liquid fuels. These fuels from biological sources are
often referred to as biofuels.
[0004] Biofuels derived from non-edible biological sources, such as
cellulosic materials, are preferred as these do not compete with
food production. These biofuels are also referred to as second
generation, or advanced, biofuels. Most of these non-edible
cellulosic materials, however, are solid materials that are
cumbersome to convert into biofuels. A first step in conversion of
these cellulosic materials is therefore a liquefaction of the
cellulosic material into a liquid.
[0005] WO2013072383 describes a process for the conversion of a
cellulosic material into a bio-oil, comprising the steps of
contacting the cellulosic material with a liquid solvent in an
inert atmosphere at a reaction temperature in the range from equal
to or more than 260.degree. C. to equal to or less than 400.degree.
C. to produce a product mixture; then separating a middle fraction
from the product mixture, to produce a product mixture middle
fraction; and recycling a first volume part of the product mixture
middle fraction to be used as part of the liquid solvent; and using
a second volume part of the product mixture middle fraction to
produce a bio-oil. It was found that the addition of water in the
feed and the removal of light and heavy products allows the
build-up of bio-oil through consecutive refill of wood without
severe increase in the by-production of heavy residual oil and the
concomitant increase in oil viscosity.
[0006] Thus, water appears to favor the liquefaction process, i.e.
water appears to be instrumental in depolymerizing the biomass.
Therefore, at present, liquefaction of biomass is performed by
using wet feedstock. Generally, liquefaction takes place in a
high-pressure reactor, suitable for continuous operation, but
possibly also in an autoclave or a similar pressure system. The
presence of water in the liquefaction process results in high
operating pressures (>80 bar) in the reactor system due to steam
formation at high operation temperature, which generally is above
300.degree. C. The high pressure in the sealed reaction system is
the autogenous pressure, being the pressure that corresponds to the
saturated vapor pressure above the solution at the specified
temperature and composition of the solution (i.e. the natural
pressure obtained upon heating the system).
[0007] Liquefaction processes may also comprise the presence of
hydrogen in the process, for instance for use in catalytic
hydrogenation of the biomass material. In the case of catalytic
hydrogenation, an extra pressure component is added to the system:
it is essential that a sufficiently high partial pressure of
hydrogen is provided. This partial pressure of hydrogen is added to
the autogenous vapor pressure of the reaction system, thus further
increasing the total pressure.
[0008] However, high pressures require the use of high pressure
reaction vessels and a feeding device that is suitable for feeding
solids and/or slurries at high pressures. Alternatively, to avoid
the pressures going up too high, pre-drying of the feedstock may be
considered, however that requires additional equipment and energy
consumption and results in lower yields or longer reaction
times.
SUMMARY OF THE INVENTION
[0009] It would be advancement in the art to provide an
economically attractive process for conversion of a cellulosic
material, which allows the use of water and hydrogen in the
liquefaction process while avoiding the above described
drawbacks.
[0010] Such advancement has been achieved with the process
according to the invention. According to the present invention, it
has been found that wet biomass (in particular lignocellulosic)
feedstock can be liquefied to bio-oil with a high oil yield at
moderate pressure under aqueous conditions while also adding
hydrogen in the presence of a catalyst. The advancement is achieved
by allowing excess pressure to escape the liquefaction vessel. It
was found that such pressure control did not have detrimental
effect on oil yield, even though a reduction of the presently
well-known beneficial effect of steam on the liquefaction process
was expected to result in lower oil yields.
[0011] Accordingly, an embodiment provides a process for the high
temperature conversion of a cellulosic material into a bio-oil,
wherein, under hydrogen atmosphere and in the presence of a
catalyst, the cellulosic material is contacted in a reaction vessel
with a liquid solvent, wherein water is present from 5% up to 80 wt
%, based on the total amount of cellulosic material and liquid
solvent present in the vessel, at a controlled operating pressure
of from equal to or more than 2.0 MPa to equal to or less than 13.0
MPa, wherein the partial hydrogen pressure contributes from equal
to or more than 1.0 MPa to equal to or less than 6.0 MPa, and the
total vapour pressure being lower than the autogenous pressure at
the operating temperature and contributing in the range of from
equal to or more than 1.0 MPa to equal to or less than 7.0 MPa, to
produce a product mixture comprising bio-oil.
[0012] The process according to the invention allows a number of
improvements when compared to prior art processes: to avoid the use
of high pressure reaction vessels, to avoid the need for high
pressure feeding devices, to avoid pre-drying the feedstock, while
still delivering high oil yields.
DETAILED DESCRIPTION OF THE INVENTION
[0013] In the process, the operating pressure (also called the "set
pressure", being the pressure which was preselected as the pressure
at which to carry out the reaction) is kept relatively low, being
from equal to or more than 1.0 MPa (10 bar absolute) to equal to or
less than 7.0 MPa (70 bar absolute). The operating pressure herein
is: the sum of all vapour pressures in the system (i.e. including
water) plus the partial pressure of hydrogen that is added to the
system from external source. The sum of all vapour pressures in the
system herein is defined as the "total vapour pressure". This
relates to the situation wherein the vapor pressure is saturated,
i.e. when there is an equilibrium with the liquid phase. According
to the invention the total vapour pressure is being kept lower than
the autogenous pressure at the operating temperature. The
autogenous pressure herein is defined herein as the highest
pressure at a certain temperature that is measured in a reactor
vessel, when a liquefaction reaction is carried at that temperature
in a fully closed vessel in the absence of externally added
hydrogen. Also here it is to be understood that the vapor pressure
is saturated, i.e. when there is equilibrium with the liquid phase.
Preferably, the operating pressure is from equal to or more than
3.5 MPa (35 bar absolute), preferably equal to or more than 4.2 MPa
(42 bar absolute), more preferably equal to or more than 5.0 MPa
(50 bar absolute), to equal to or less than 11.0 MPa (110 bar
absolute), preferably equal to or less than 10.0 MPa (100 bar
absolute), especially equal to or less than 9.0 MPa (90 bar
absolute).
[0014] In an embodiment of the invention, the operating pressure of
the reactor vessel is set such that the total vapour is less than
90% of the steam saturation pressure that corresponds to the
operating reaction temperature applied, preferably <80%, more
preferably <70%, more preferably <50% of the steam saturation
pressure. For reference, the steam saturation pressure amounts to
about 4 MPa and to about 8 MPa at 250.degree. C. and 300.degree.
C., respectively, as can be found in engineering text books (CRC
Handbook of Chemistry and Physics, 83.sup.rd Ed., D. R. Lide (Ed.),
2003, p 6-10 to 6-11).
[0015] In another embodiment, the operating pressure is set such
that the total vapour pressure is less than 90% of the autogenous
pressure of the reaction medium, at the operating reaction
temperature applied. Preferably, the operating pressure is set such
that the total vapour pressure is at <80%, more preferably
<70%, more preferably <50% of the autogenous pressure of the
reaction medium. For reference, the use of a high-boiling liquid
solvent such as guaiacol or methylnaphthalene at about 300.degree.
C. leads to a liquid solvent vapour pressure of 1-1.5 MPa, to which
a steam saturation pressure of about 8 MPa, may add to constitute
the largest part of the autogenous pressure, depending on water
concentration.
[0016] Preferably, the total vapour pressure contribution to the
operating pressure is in the range from equal to or more than 2.0
MPa (20 bar absolute), preferably equal to or more than 2.5 MPa (25
bar absolute), more preferably equal to or more than 3.0 MPa (30
bar absolute), to equal to or less than 6.0 MPa (60 bar absolute),
preferably equal to or less than 5.5 MPa (55 bar absolute),
especially equal to or less than 5.0 MPa (50 bar absolute).
[0017] Preferably, the partial hydrogen pressure contribution to
the operating pressure is from equal to or more than 1.5 MPa (15
bar absolute), preferably equal to or more than 1.7 MPa (17 bar
absolute), more preferably equal to or more than 2.0 MPa (20 bar
absolute) to equal to or less than 5.0 MPa (50 bar absolute),
preferably equal to or less than 4.0 MPa (40 bar absolute),
especially equal to or less than 3.0 MPa (30 bar absolute).
[0018] The pressure may be controlled using any system known in the
art. In an embodiment, the reaction vessel is provided with a
pressure control system that opens a pressurization valve and shuts
it once the internal pressure has reached a certain setpoint in the
desired pressure range ("set pressure"). Depressurization occurs
when the dump valve is opened. The valves may be used in an on/off
operation rather than modulating, for cost reasons.
[0019] In another embodiment, the reaction vessel is equipped with
an open gas restriction outlet that leads to a compartment of low
but controlled pressure, e.g. atmospheric or near atmospheric
pressure, which is also to be understood as being a pressure
control system. The gas restriction outlet is designed such as to
control the escape of gas via a pressure drop forced onto the
restriction. The higher the pressure drop, i.e. the higher the
pressure inside the reaction vessel, the higher the gas escape
flow. The gas restriction outlet may be of fixed opening or
adjustable opening as applied e.g. in flow-control valves.
[0020] In an embodiment, the process of the invention comprises
condensing at least part of the reaction products and solvents
including water exiting the reactor as vapour, into liquid
components in a post reaction separator. Preferably at least 10%,
more preferably at least 25%, most preferably at least 50% by
weight of the total liquid feed (including solvent components and
water provided as "fresh" feed, formed in the reactor or recycled
to the reactor) exits the reactor in the vapour phase, such that
the mass flow of liquid components out of the reactor is less than
the feed by this amount.
[0021] In the process of the invention, the added hydrogen gas
functions as "stripping" gas, this insures that hydrogen partial
pressure is higher than it otherwise would be, by removing by
vapour-liquid equilibrium the more volatile components of the feed,
or formed from the feed. Thus, one can directly measure the "amount
of stripping" of liquid components, taking for example the amounts
of liquid at ambient temperature and pressure for feed (including
any recycle or added solvent) vs. product from reactor, using room
temperature and pressure as convenient condition for
comparison.
[0022] The hydrogen referred to in the reaction of the current
invention is "externally added" hydrogen, referring to hydrogen
that does not originate from the cellulosic feedstock of the
reaction itself, but rather is added to the system from another
source, which may be any suitable source of gaseous hydrogen.
Hydrogen is consumed in the high temperature conversion of the
cellulosic material. Further, by controlling the pressure according
to the invention, hydrogen also escapes the reaction system.
However, the loss of hydrogen as a result of the escaping gas flow
and the reaction is adjusted by adding extra hydrogen to the system
to maintain the desired partial pressure of H.sub.2.
[0023] The wording "high temperature conversion of a cellulosic
material" as used herein may also be referred to herein as
liquefaction, and the product mixture obtained may also be referred
to herein as liquefaction product. In such a liquefaction process
the cellulosic material is liquefied. By liquefaction (also herein
referred to as liquefying) is herein understood the--at least
partial--conversion of a solid material, such as cellulosic
material, into one or more liquefied products.
[0024] By a liquefied product is herein understood a product that
is liquid at ambient temperature (20.degree. C.) and pressure (0.1
MPa) and/or a product that can be converted into a liquid by
melting (for example by applying heat) or dissolving in a solvent.
Preferably the liquefied product is a liquefied product that is
liquid at a temperature of 80.degree. C. and a pressure of 0.1 MPa.
The liquefied product may vary widely in its viscosity and may be
more or less viscous.
[0025] Liquefaction of a cellulosic material can comprise cleavage
of covalent linkages in that cellulosic material. For example
liquefaction of lignocellulosic material can comprise cleavage of
covalent linkages in cellulose, hemicellulose and/or lignin present
and/or cleavage of covalent linkages between lignin, hemicelluloses
and/or cellulose.
[0026] As used herein, a cellulosic material refers to a material
containing cellulose. Preferably the cellulosic material is a
lignocellulosic material. A lignocellulosic material comprises
lignin, cellulose and optionally hemicellulose.
[0027] Advantageously, according to the process of the invention,
not only the cellulose is liquefied but also the lignin and
hemicelluloses.
[0028] Any suitable cellulose-containing material may be used as
cellulosic material in the process according to the present
invention. The cellulosic material for use according to the
invention may be obtained from a variety of plants and plant
materials including agricultural wastes, forestry wastes, sugar
processing residues and/or mixtures thereof. Examples of suitable
cellulose-containing materials include agricultural wastes such as
corn stover, soybean stover, corn cobs, rice straw, rice hulls, oat
hulls, corn fibre, cereal straws such as wheat, barley, rye and oat
straw; grasses; forestry products such as wood and wood-related
materials such as sawdust; waste paper; sugar processing residues
such as bagasse and beet pulp; or mixtures thereof.
[0029] Although wet feedstock may be used according to the process
of this invention, the process may optionally comprise a
pretreatment step comprising drying, torrefaction, steam explosion,
particle size reduction, densification and/or pelletization of the
cellulosic material before the cellulosic material is contacted
with the liquid solvent. Such drying, torrefaction, steam
explosion, particle size reduction, densification and/or
pelletization of the cellulosic material may allow to adjust the
amount of water present in the feedstock for improved process
operability and economics.
[0030] Before being used in the process of the invention, the
cellulosic material is preferably processed into small particles.
Preferably, the cellulosic material is processed into particles
having a particle size distribution with an average particle size
of equal to or more than 0.05 millimeter, more preferably equal to
or more than 0.1 millimeter, most preferably equal to or more than
0.5 millimeter and preferably equal to or less than 20 centimeters,
more preferably equal to or less than 10 centimeters and most
preferably equal to or less than 3 centimeters. For practical
purposes the particle size in the centimeter and millimeter range
can be determined by sieving.
[0031] If the cellulosic material is a lignocellulosic material it
may also have been subjected to a pre-treatment to remove and/or
degrade lignin and/or hemicelluloses. Examples of such
pre-treatments include fractionation, pulping and torrefaction
processes.
[0032] In another embodiment, before use in the process of the
invention, the cellulosic material may be wet when introduced into
the reaction vessel. Suitably, the cellulosic material may comprise
from 2 wt %, preferably from 10 wt %, even more preferably from 25
wt % to 50 wt % of water based on the total amount of cellulosic
material, when introduced into the reaction vessel. The cellulosic
material may be dried or may be only partly dried to reach a
preferred water content of 2 to 30 wt % based on the total weight
of cellulosic material and liquid present in the reaction vessel.
Optionally, the cellulosic material can be impregnated with water
to reach the moisture content of 2 to 30 w %. In the case that the
cellulosic material is wet when introduced into the reaction
vessel, it may not be necessary to also add water to the
system.
[0033] The amount of water in a cellulosic material may
conveniently be determined by drying, for example according to
ASTM-method D2216-98.
[0034] The catalyst used in the process of the invention is
selected from Cr, Mo, W, Re, Mn, Cu, Cd, Fe, Co, Ni, Pt, Pd, Rh,
Ru, Ir, Os, and alloys or any combination thereof, either alone or
with promoters such as Au, Ag, Cr, Zn, Mn, Ni, Sn, Bi, B, O, and
alloys or any combination thereof. The catalyst can also include a
carbonaceous pyropolymer catalyst containing transition metals
(e.g., chromium, molybdenum, tungsten, rhenium, manganese, copper,
cadmium) or Group VIII metals (e.g., iron, cobalt, nickel,
platinum, palladium, rhodium, ruthenium, iridium, and osmium). In
certain embodiments, the catalyst includes any of the above metals
combined with an alkaline earth metal oxide or adhered to a
catalytically active support. The catalyst preferably includes a
catalyst support material, selected from any suitable inorganic
oxide material that is typically used to carry catalytically active
metal components. Examples of possible useful inorganic oxide
materials include alumina, silica, silica-alumina, magnesia,
zirconia, boria, titania and mixtures of any two or more of such
inorganic oxides. The preferred inorganic oxides for use as support
material are alumina, silica, silica-alumina and mixtures thereof.
Most preferred, however, is alumina. The catalyst used in the
process of the invention is preferably sulfided according to
methods known in the art. A preferred catalyst in the process of
the invention is a sulfided catalyst comprising cobalt and
molybdenum, optionally comprising a promoter, preferably a
nickel-oxide promoter.
[0035] The process of the invention is carried out under hydrogen
atmosphere. Preferably, hydrogen is bubbled through the reaction
mixture, most preferably while being introduced from the bottom of
the reactor vessel.
[0036] By a liquid solvent herein is understood a solvent that has
a sufficiently low volatility to avoid the solvent being released
through the system that is used to control the pressure. Suitably,
the solvent should have a vapour pressure at the operating
temperature that is lower than the set pressure/operating pressure,
preferably at least 0.5, more preferably 1, particularly 1.5 MPa
below the set pressure. Preferably, the solvent is liquid at a
pressure of 0.1 MPa (1 bar absolute) and a temperature of
80.degree. C. or higher, more preferably 100.degree. C. or higher.
Most preferably a liquid solvent is herein understood to be a
solvent that is liquid at the reaction temperature and operating
reaction pressure at which liquefaction is carried out. Hence, the
liquid solvent is preferably a solvent which is liquid at a
temperature in the range from equal to or more than 180.degree. C.
to equal to or less than 300.degree. C. at a pressure of 0.1
MPa.
[0037] Preferably the liquid solvent is an organic solvent, which
is herein understood to be a solvent comprising one or more
hydrocarbon compounds. By a hydrocarbon compound is herein
understood a compound that contains at least one hydrogen atom and
at least one carbon atom, more preferably a hydrocarbon compound is
herein understood to contain at least one hydrogen atom and at
least one carbon atom connected to each other via at least one
covalent bond. In addition to the hydrogen atom(s) and carbon
atom(s) the hydrocarbon may contain heteroatoms such as for example
oxygen, nitrogen and/or sulphur.
[0038] In a preferred embodiment the organic solvent comprises one
or more carboxylic acids. By a carboxylic acid is herein understood
a hydrocarbon compound comprising at least one carboxyl (--CO--OH)
group. More preferably the organic solvent comprises equal to or
more than 1 wt % carboxylic acids, more preferably equal to or more
than 10 wt % carboxylic acids, most preferably equal to or more
than 20 wt % of carboxylic acids, based on the total weight of
organic solvent. There is no upper limit for the carboxylic acid
concentration, but for practical purposes the organic solvent may
comprise equal to or less than 90 wt %, more preferably equal to or
less than 80 wt % of carboxylic acids, based on the total weight of
organic solvent.
[0039] In another preferred embodiment the liquid solvent comprises
at least one phenolic group, optionally with side groups such as
alkyl- or alkoxygroups. Preferably, the liquid solvent comprises at
least 1 wt % methoxyphenols, more preferably at least 10 wt %
methoxyphenols, even more preferably at least 20 wt %
methoxyphenols, based on the total weight of the liquid
solvent.
[0040] In another embodiment the liquid solvent comprises
paraffinic compounds, naphthenic compounds, olefinic compounds
and/or aromatic compounds. Such compounds may be present in
refinery streams such as gasoil and/or fuel oil.
[0041] The liquid solvent used in the conversion of the cellulosic
feedstock comprises water in an amount of less than or equal to 80
wt %, preferably in an amount of less than or equal to 70 wt %,
more preferably less than or equal to 60 wt %, and most preferably
less than or equal to 50 wt %, based on the total weight of liquid
solvent. Water may be present in the liquid solvent in an amount of
more than or equal to 5 wt %, preferably more than or equal to 8 wt
%, and more preferably in an amount of more than or equal to 10 wt
%, based on the total weight of the liquid solvent. The water in
the liquid solvent may for example be generated in-situ during the
conversion.
[0042] In an embodiment of the invention, the process comprises
recycling (a part of) the product mixture to be used as part of the
liquid solvent. Evidently, that part of the product mixture also
should have a vapour pressure at the operating temperature that is
lower than the operating pressure as required for the liquid
solvent. In the process of the invention, preferably at least part
of the liquid solvent consists of a recycled product fraction. The
liquid solvent preferably comprises equal to or more than 10 wt %,
more preferably equal to or more than 20 wt %, even more preferably
equal to or more than 30 wt %, still more preferably equal to or
more than 50 wt %, most preferably equal to or more than 80 wt %
and preferably equal to or less than 100 wt %, possibly equal to or
less 90 wt %, based on the total weight of liquid solvent used in
the conversion, of a recycled product fraction.
[0043] In an embodiment, for use in the liquefaction process, the
recycled product may be mixed with one or more hydrocarbon
compound(s) that are derived from a source other than the
cellulosic material used as a feedstock, for example a hydrocarbon
compound derived from a petroleum source (herein also referred to
as fossil source).
[0044] In a further embodiment, the process of the invention
comprises contacting the cellulosic feed material with a liquid
solvent comprising recycled product and water.
[0045] The cellulosic material and the total liquid solvent (i.e.
also including water) in the conversion process are preferably
contacted in a liquid solvent-to-cellulosic material weight ratio
of 2:1 to 20:1, more preferably in a liquid solvent-to-cellulosic
material weight ratio of 3:1 to 15:1 and most preferably in a
liquid solvent-to-cellulosic material weight ratio of 4:1 to
10:1.
[0046] The operating temperature at which the conversion of the
cellulosic material is carried out according to the invention is in
the range from equal to or more than 180.degree. C. to equal to or
less than 300.degree. C. Preferably, the operating temperature is
in the range from equal to or more than 190.degree. C. to equal to
or less than 275.degree. C., more preferably in the range from
equal to or more than 200.degree. C. to equal to or less than
260.degree. C. The operating temperature may also be a staged
temperature profile, i.e. starting at a lower temperature for a
certain period of time, followed by a higher temperature for
another period of time. Preferably, a staged temperature profile
comprises 1 hour at 200.degree. C. and 4 hours at 250.degree.
C.
[0047] The process according to the invention can be carried out
batch-wise, semi-batch wise, continuously and/or in a combination
thereof. The process may for example be carried out in a
continuously stirred tank reactor or in a plug flow reactor or a
combination thereof. In a preferred embodiment, the process is
carried out in a plug flow reactor.
[0048] Preferably, the residence time in any reactor for the
conversion process lies in the range from equal to or more than 15
minutes, preferably equal or more than 30 minutes, more preferably
equal to or more than 45 minutes, even more preferably equal to or
more than 60 minutes; to equal to or less than 7 hours, more
preferably equal to or less than 6 hours, even more preferably
equal to or less than 5 hours, still more preferably equal to or
less than 4 hours.
[0049] The product mixture may contain solids (such as unconverted
cellulosic material and/or humins and/or char); liquids (such as
water and/or hydrocarbon compounds); and/or gas.
[0050] The process of the invention advantageously allows one to
produce a product mixture with a viscosity preferably in the range
from 1 to 2000 centipoises (cP) at 30.degree. C., more preferably a
viscosity in the range from 1 to 1000 centipoises (cP) at
30.degree. C., and most preferably a viscosity in the range from 2
to 500 centipoises (cP) at 30.degree. C. As explained herein a
middle fraction of the product mixture is recycled and used as part
of the liquid solvent in the liquefaction process. Therefore the
liquid solvent may also have a viscosity preferably in the range
from 1 to 2000 centipoises (cP) at 30.degree. C., more preferably a
viscosity in the range from 1 to 1000 centipoises (cP) at
30.degree. C., and most preferably a viscosity in the range from 2
to 500 centipoises (cP) at 30.degree. C. The viscosity may depend
on the number of recycles completed. For example, a product mixture
respectively liquid solvent may comprise at least 10 wt %, more
preferably at least 30 wt % and most preferably at least 50 wt %
(based on the total weight of product mixture respectively liquid
solvent) of a 3rd generation or higher generation reaction products
and preferably have a viscosity in the range from 2 to 500
centipoises (cP) at 30.degree. C., more preferably a viscosity in
the range from 2 to 100 centipoises (cP); or for example a product
mixture respectively liquid solvent may comprise at least 10 wt %,
more preferably at least 30 wt % and most preferably at least 50 wt
% (based on the total weight of product mixture respectively liquid
solvent) of a 5th generation or higher generation reaction products
and preferably have a viscosity in the range from 10 to 1000
centipoises (cP) at 30.degree. C., more preferably a viscosity in
the range from 20 to 500 centipoises (cP) at 30.degree. C.
[0051] In an embodiment of the invention, after the (partial)
conversion of the cellulosic material, the process comprises a
subsequent step wherein the product mixture is separated into a
light fraction comprising (hydrocarbon) compounds having a
molecular weight of less than 100 grams per mol; a middle fraction
comprising (hydrocarbon) compounds having a molecular weight in the
range from equal to or more than 100 grams per mol to equal to or
less than 1,000 grams per mol; and a heavy fraction comprising
(hydrocarbon) compounds having a molecular weight of more than
1,000 grams per mol. The middle fraction may preferably be selected
from the product mixture, to produce a fraction for use in
recycling. The hydrocarbon compounds may also contain heteroatoms
such as sulphur, oxygen and/or nitrogen.
[0052] The fractions may be separated from the product mixture
using any kind of separation technique known by the person skilled
in the art, including for example filtration, settling,
fractionation (including atmospheric or vacuum distillation and/or
flashing), centrifugation, cyclone separation, membrane separation
and/or membrane filtration, phase separation, (solvent) extraction
and/or a combination thereof. The product mixture middle fraction
preferably comprises one or more oxygenates, more preferably two or
more oxygenates. By an oxygenate is herein understood a hydrocarbon
compound that contains at least one oxygen atom, more preferably by
an oxygenate is herein understood a hydrocarbon compound further
containing at least one oxygen atom bonded to a carbon atom via at
least one covalent bond. Examples of oxygenates include hexanoic
acid (boiling at about 205.degree. C. at 0.1 MPa), pentanoic acid
(boiling at about 186-187.degree. C. at 0.1 MPA), levulinic acid
(boiling at about 245-246.degree. C. at 0.1 MPa), guaiacol (boiling
at about 204-206.degree. C. at 0.1 MPa), syringol (boiling at about
261.degree. C. at 0.1 MPA) and/or gamma-valerolactone (boiling at
about 207-208.degree. C. at 0.1 MPa). Preferably the product
mixture middle fraction is a fraction of which at least 90 wt % has
a boiling temperature of equal to or more than 150.degree. C. at
0.1 MPa and of which 90 wt % melts at a temperature equal to or
less than the reaction temperature.
[0053] In a further embodiment the process comprises an additional
step comprising hydrotreatment of at least part of the produced
bio-oil. The hydrotreatment may for example comprise hydrogenation,
hydrooxygenation and/or hydrodesulphurization using technologies
and methods known in the art.
[0054] In a another embodiment the process according to the
invention may further comprise a catalytic cracking step,
preferably a fluidized catalytic cracking step, for example
comprising contacting a feed comprising at least part of the
bio-oil--which bio-oil may optionally have been hydrotreated--with
a fluidized catalytic cracking catalyst at a temperature of equal
to or more than 400.degree. C., preferably a temperature in the
range of equal to or more than 450.degree. C. to equal to or less
than 800.degree. C., to produce one or more cracked products.
[0055] In the catalytic cracking step one or more cracked products
are produced. In a preferred embodiment this/these one or more
cracked products is/are subsequently fractionated and/or
hydrotreated to produce one or more base fuels.
[0056] Such a base fuel may conveniently be blended with one or
more other components to produce a biofuel or biochemical. Examples
of such one or more other components include anti-oxidants,
corrosion inhibitors, ashless detergents, dehazers, dyes, lubricity
improvers and/or mineral fuel components, but also conventional
petroleum derived gasoline, diesel and/or kerosene fractions.
[0057] By a biofuel is herein understood a fuel that is at least
party derived from a renewable energy source. The biofuel may
advantageously be used in the engine of a transportation
vehicle.
EXAMPLES
[0058] The invention will now be further illustrated by means of
the following non-limiting examples and comparative examples.
Examples 1-4
[0059] 75-ml Parr5000 reactors were charged with a nominal 14 grams
of tetrahydrofurfural alcohol, 6 grams of methoxypropylphenol, and
2 grams of deionized water. 0.12 grams of potassium carbonate was
added as buffer, together with 0.35 grams of nickel-oxide promoted
cobalt molybdate catalyst (DC-2534, containing 1-10% cobalt oxide
and molybdenum trioxide (up to 30 wt %) on alumina, and less than
2% nickel), obtained from Criterion Catalyst & Technologies
L.P., and sulfided by the method described in US2010/0236988
Example 5).
[0060] For each cycle of reaction, 2.0 grams of cellulosic floc
(Leslie's Swimming Pool Supplies; nominal 200 microns) were added,
followed by pressuring with varying amounts of hydrogen under
stirring via stir bar. The reactor was heated to 190.degree. C. for
1 hour, followed by 250.degree. C. for 4 hours to complete the
digestion and reaction of cellulose.
[0061] The process was repeated for 3 cycles of cellulose addition,
with addition of sodium carbonate buffer as needed to maintain pH
between 5-7. At the end of 3 cycles the reactor contents separated
by filtration in a vacuum filter flask (Whatman GF/F paper).
Recovered solids were negligible.
[0062] The aqueous product was analyzed by gas chromatography
("DB5-ox method") using a 60-m.times.0.32 mm ID DB-5 column of 1
.mu.m thickness, with 50:1 split ratio, 2 ml/min helium flow, and
column oven at 40.degree. C. for 8 minutes, followed by ramp to
285.degree. C. at 10.degree. C./min, and a hold time of 53.5
minutes. The injector temperature was set at 250.degree. C., and
the detector temperature was set at 300.degree. C. A range of
alkanes, ketone and aldehyde monooxygenates as well as glycol
solvents and products, and polyols (glycerol) were observed, with
volatility greater than C6 sugar alcohol sorbitol. GC measured
products indicated a selectivity of 48% to products with volatility
greater than sorbitol (C6 monomer), relative to the carbohydrate
content of the digested portion of the wood initially charged.
[0063] For Examples 1-4, the initial hydrogen partial pressure was
varied from 3.4 to 51 bar. The total GC wt % of observable products
was observed to increase as the H.sub.2 partial pressure was
increased above 3.4 bar, with a maximum at 35 bar. The remainder of
products was attributed for formation of heavy tars, which could
not be eluted from the G.C.
TABLE-US-00001 TABLE 1 Yields from cellulose vs. H.sub.2 partial
pressure H.sub.2 bar GC wt % 51.0 17.7 34.0 19.7 17.0 19.2 3.4
4.1
Example 5: Stripping Reactor Numerical Simulation
[0064] A process simulation model (Aspen Process Model V7.3) was
created with a simulated wood feed composition (66% H.sub.2O) and
model reactions to form alcohol and phenolic products modelled by
phenol, C.sub.6-alcohol, glycerol, and ethanol products. The
digester-reactor pressure was set at 41 bar, and temperature was
set at 250.degree. C. Following reaction, the vapour and liquid
components were collected and cooled to 170.degree. C. also at 41
bar, for separation in to vapour and liquid phases. The liquid
phase contained only 8% by weight of water, but 41% phenol, 44%
C6-alcohol and 5% glycerol. Solvent recycle was set at twice the
wood feed flow, and the H.sub.2 feed was varied to assess flowrate
required to strip ethanol plus water vapour, and maintain a target
H.sub.2 partial pressure in the digester-reactor. A flowrate of 6
liters per hour (standard pressure and temperature) of hydrogen per
gram/hour of wood feed, was enough to maintain a H.sub.2 partial
pressure of 35 bar in the digester reactor, relative to water
vapour stripped.
[0065] This example demonstrates the use of H.sub.2 stripping at a
flowrate sufficient to maintain a high partial pressure of H.sub.2
(35 bar) for a digester-reactor operated at 41 bar with liquid
phase feed components which in the absence of stripping would
contribute a vapour pressure in excess of 25 bar.
Examples 6-9: Microflow Stripping Reactor
[0066] A 0.5 inch outside diameter by 10-inch microflow reactor was
packed with a bottom zone 2.5-inch zone of 1/8-inch Denstone
support. 1.68 grams of crushed sulfided cobalt molybdate catalyst
(as described in Example 1) were added on top of the support,
followed by a 6.8 inch bed of comprising 6.9 grams of ground
southern pine wood (52% moisture). The reactor was filled with a
solvent of 90% tetrahydrofurfural alcohol in deionized water. 41
bar of H.sub.2 backpressure was applied, and H.sub.2 was sparged at
the bottom of the reactor at 50 ml/min, as temperature was
increased to 200.degree. C. for 1 hour, followed by 250.degree. C.
for 4 hours, during which time fresh solvent mixture was added at
0.04 ml/min.
[0067] After 5 hours, a total of 23.57 grams of liquid product were
collected via a product vessel separator on the vent gas line,
relative to 16.1 grams of solvent fed. At the end of this run, the
reactor was cooled, opened and an additional 6.04 grams of Southern
pine wood were added, to replace that digested in cycle 1, along
with 8.6 grams of solvent to replace the net amount stripped from
the reactor.
[0068] This process was continued through 5 cycles of wood addition
entailing 6.9, 6.04, 5.45, 5.69, and 5.31 grams of wood addition.
Deinventory of the reactor after 5 cycles yielded 4.35 grams of
undigested wood at 55% moisture content. Overall digestion was 85%
of the total mass of wood injected for the 5 cycles of operation.
GC analysis again revealed a range of GC observable products
including ethylene glycol, propylene glycol, and ethanol. Total
products observed were estimated as corresponded to greater than
50% of the conversion of the carbohydrate fraction of wood fed.
[0069] This example demonstrates the operation of a flow reactor
with continuous stripping of hydrogen gas at a total pressure of 41
bar equal to the vapour pressure of water at the digester
temperature employed (250.degree. C.), under conditions where
substantial liquid solvent (40-60%) was stripped beyond that
provided as makeup liquid feed, and a majority (greater than 85%)
of wood was digested to soluble products.
* * * * *