U.S. patent application number 12/742213 was filed with the patent office on 2010-12-16 for use of methanol in the production of hydrogen and fuel, processes and plants for the production of hydrogen and fuel.
This patent application is currently assigned to UPM-KYMMENE OYJ. Invention is credited to Pekka Jokela, Pekka Knuuttila, Petri Kukkonen.
Application Number | 20100317905 12/742213 |
Document ID | / |
Family ID | 39386023 |
Filed Date | 2010-12-16 |
United States Patent
Application |
20100317905 |
Kind Code |
A1 |
Kukkonen; Petri ; et
al. |
December 16, 2010 |
Use of Methanol in the Production of Hydrogen and Fuel, Processes
and Plants for the Production of Hydrogen and Fuel
Abstract
The invention relates to the use of biomethanol from the pulp
industry in the production of biohydrogen. The preferred
biomethanol comprises purified biomethanol derived from black
liquor. The invention also relates to a process for the production
of biohydrogen from crude biomethanol recovered from black liquor
and to a process for producing hydrocarbon biofuel using such
biohydrogen as a hydrogen source. The invention further relates to
a biofuel production facility for producing fuel from biohydrogen
and biohydrocarbon, and to biofuel so produced. The invention makes
it possible to produce a biofuel, wherein 100% of the raw material
stems from non-fossil sources.
Inventors: |
Kukkonen; Petri; (Helsinki,
FI) ; Knuuttila; Pekka; (Porvoo, FI) ; Jokela;
Pekka; (Espoo, FI) |
Correspondence
Address: |
STEPTOE & JOHNSON LLP
1330 CONNECTICUT AVENUE, N.W.
WASHINGTON
DC
20036
US
|
Assignee: |
UPM-KYMMENE OYJ
Helsinki
FI
|
Family ID: |
39386023 |
Appl. No.: |
12/742213 |
Filed: |
October 29, 2008 |
PCT Filed: |
October 29, 2008 |
PCT NO: |
PCT/EP2008/064675 |
371 Date: |
August 23, 2010 |
Current U.S.
Class: |
585/254 ;
422/608; 422/609; 422/610; 422/611; 422/612; 423/648.1 |
Current CPC
Class: |
C10J 2300/1678 20130101;
Y02E 20/16 20130101; C10G 3/00 20130101; C10G 45/58 20130101; C10J
2300/169 20130101; C01B 2203/0233 20130101; C10J 2300/0916
20130101; C10L 2290/54 20130101; C10G 2/32 20130101; C01B 3/52
20130101; C10K 1/101 20130101; C10J 2300/0959 20130101; C02F
2103/28 20130101; C10L 1/04 20130101; Y02E 50/30 20130101; Y02E
50/32 20130101; C01B 3/48 20130101; C01B 2203/0283 20130101; C01B
2203/0415 20130101; C02F 3/00 20130101; C10K 3/04 20130101; C10G
3/50 20130101; C01B 3/382 20130101; C10G 2300/1003 20130101; C10G
2300/1011 20130101; D21C 11/0007 20130101; Y02P 20/145 20151101;
C01B 3/323 20130101; C02F 1/00 20130101; C01B 13/0248 20130101;
C10J 2300/1659 20130101; C10L 2200/0469 20130101; C01B 2203/043
20130101; Y02E 20/18 20130101; C01B 2203/049 20130101; Y02P 30/20
20151101; C02F 2103/16 20130101; C10L 2290/42 20130101; C10G 2/30
20130101; C01B 2210/0046 20130101; C01B 2203/0465 20130101; C01B
2203/1223 20130101; C02F 2101/34 20130101; C01B 2203/048 20130101;
C10J 2300/16 20130101; C02F 2103/023 20130101; C02F 2103/365
20130101; D21C 11/06 20130101; C10J 3/00 20130101; C01B 2203/0244
20130101 |
Class at
Publication: |
585/254 ;
423/648.1; 422/608; 422/609; 422/610; 422/611; 422/612 |
International
Class: |
C07C 1/20 20060101
C07C001/20; C01B 3/02 20060101 C01B003/02; B01J 8/00 20060101
B01J008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 9, 2007 |
FI |
20075794 |
Apr 30, 2008 |
FI |
20085400 |
Jul 4, 2008 |
FI |
20085697 |
Claims
1. Use of biomethanol derived from the pulp industry for the
production of biohydrogen.
2. The use according to claim 1, wherein said biomethanol comprises
purified biomethanol derived from black liquor.
3. The use according to claim 1, wherein said biomethanol is
recovered from black liquor by distillation and/or stripping.
4. The use according to claim 1, 2 or 3, wherein said biohydrogen
is used for producing hydrocarbon biofuel.
5. The use according to claim 4, wherein said biohydrogen is used
in a biofuel production process step selected from the steps of
adjusting the hydrogen to carbon monoxide ratio of syngas,
cracking/isomerization of Fischer-Tropsch paraffins,
hydrodeoxygenation of natural oils, hydroisomerization of
n-paraffins, reduction of catalysts and combinations thereof.
6. The use according to claim 5, wherein all of said steps are
performed in a biofuel production facility integrated with a pulp
and/or paper mill.
7. A process for the production of biohydrogen, characterized in
that crude biomethanol recovered from black liquor is purified and
reformed, where after biohydrogen is recovered.
8. The process according to claim 7, wherein said purification
includes steps selected from washing, scrubbing, stripping,
liquid-liquid separation, distillation, catalytic conversion, ion
exchange, absorption and adsorption.
9. The process according to claim 7 or 8, wherein said reforming
comprises autothermal reforming or steam reforming.
10. The process according to any one of the preceding claims 7 to
9, wherein said biohydrogen is recovered by separating it from
carbon dioxide in a pressure swing adsorption unit.
11. A process for producing hydrocarbon biofuel, characterized in
that a) crude biomethanol recovered from black liquor is purified
and reformed to provide biohydrogen and purified biohydrogen is
recovered; b) a biohydrocarbon stream is produced by a process
selected from a Fischer-Tropsch reaction of syngas produced from
biomass, a hydrodeoxygenation of biological triglycerides or fatty
acids and combinations thereof, wherein c) said biohydrocarbon
stream production of step b) includes at least one process step
selected from adjusting the hydrogen to carbon monoxide ratio of
syngas, cracking/isomerization of Fischer-Tropsch paraffins,
hydrodeoxygenation of said biological triglycerides or fatty acids,
hydroisomerization of n-paraffins, and reduction of catalysts; and
d) said purified biohydrogen recovered in step a) is used as a
hydrogen source in at least one of the process steps defined in
step c) and the biohydrocarbon stream produced is separated into
fractions and biofuel is recovered from at least one of said
fractions.
12. A process according to claim 11, wherein said biomass comprises
biological waste or by-products of wood processing industry.
13. A process according to claim 11 or 12, wherein said
triglycerides or fatty acids comprise tall oil or tall oil fatty
acids.
14. A process according to claim 11, wherein said biomethanol is
reformed together with gaseous stream(s), which emanate(s) from one
or more process steps of said biofuel production process and which
contain(s) gaseous components capable of forming hydrogen by
reforming.
15. A biofuel production facility, characterized in that it
comprises a Kraft pulp mill (19), which provides black liquor; a
recovery unit (12) for recovering of crude biomethanol from said
black liquor; a methanol purification unit (13) for purification of
said crude biomethanol to produce purified biomethanol; a reforming
unit (7) for reforming of said purified biomethanol to produce a
gas mixture containing biohydrogen; a hydrogen purification unit
(8) for purification of said gas mixture to provide purified
biohydrogen; and a biofuel production plant (20), which produces
biohydrocarbon based biofuel from said biohydrogen and from
biomass.
16. The biofuel production facility of claim 15, wherein said
biomass includes biological waste and/or by-products of said Kraft
pulp mill.
17. The biofuel production facility of claim 15, wherein said
recovery unit (12) for said biomethanol comprises means selected
from a stripping unit and a distillation unit and combinations
thereof.
18. The biofuel production facility according to claim 15, wherein
said methanol purification unit (13) for purification of
biomethanol comprises means selected from a scrubbing unit, a
washing unit, a stripping unit, an adsorbing unit, an absorbing
unit, a catalytic reactor unit and combinations thereof.
19. The biofuel production facility according to any one of the
preceding claims 15 to 18, wherein said reforming unit (7)
comprises an autothermal reforming unit or a steam reforming
unit.
20. The biofuel production plant according to any one of claims 15
to 19, wherein said hydrogen purification unit (8) comprises at
least one adsorbing unit.
21. Biofuel made of waste and/or by-products of wood processing
industry, characterized in that said biofuel is made of
biohydrocarbons produced from biological waste and/or by-products
of a Kraft pulp mill and biohydrogen produced from black liquor.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the use of biomethanol
derived from the pulp industry in the production of biohydrogen.
The preferred biomethanol comprises purified biomethanol derived
from black liquor. The invention also relates to a process for the
production of biohydrogen from biomethanol derived from black
liquor and to a process for producing hydrocarbon biofuel using
such biohydrogen as a hydrogen source. Finally, the present
invention relates to a biofuel production facility for producing
fuel from biohydrogen and biohydrocarbon, and to biofuel so
produced.
[0002] The present invention provides improvements to known ways of
utilizing biomaterials to produce biofuel by processes which
produce hydrocarbons, such as Fischer-Tropsch and
hydrodeoxygenation. The biohydrogen of the present invention can be
used for upgrading the intermediate hydrocarbons to end products
having desired chemical and physical properties. All the processes
mentioned above require hydrogen as a reagent and many of the
reactions preferably occur under hydrogen pressure.
[0003] The present invention provides an advantage for the wood
processing industry by facilitating utilization of one of its low
value by-products, namely biomethanol. The use of the biomethanol
for the production of biohydrogen means that hydrocarbon biofuel
products can be produced with 100% bio-character. In the prior art,
the biofuel production was typically dependent on outside hydrogen
usually produced by steam reforming of natural gas.
BACKGROUND OF THE INVENTION
[0004] The diminishing reserves of fossil fuels and the emission of
harmful gases connected with their use have increased the interest
in utilizing biological materials, especially from non-edible
renewable resources for making liquid fuels capable of replacing
fossil ones. Several prior art processes are known for producing
liquid fuels from biological starting materials. One that has
reached commercial success comprises the production of biodiesel
(FAME) by transesterification of biomass-derived oils with
alcohols.
[0005] Biofuel has also been successfully made from hydrocarbons
produced from biomass gasification products via Fischer-Tropsch
synthesis and from hydrocarbons produced by hydrodeoxygenation of
triglycerides and fatty acids of biological origin. Furthermore,
alcohols such as ethanol and methanol made from biological
materials have been proposed for use as replacements for fossil
fuels in combustion engines.
[0006] Methanol is the simplest one of the alcohols and it has the
chemical formula of CH.sub.3OH. It is used as a solvent and as an
industrial chemical in the manufacture of a wide range of raw
materials including formaldehyde, methyl tert-butyl ether (MTBE),
acetic acid dimethyl terephtalate (DMT), methyl methacrylate (MMA)
methyl amines, antifreeze agents, etc. Methanol has also been
suggested for use in the production of non-fossil fuels such as
fatty acid methyl esters (FAME), dimethylether (DME),
methanol-to-gasoline (MTG) and methanol-to-olefins (MTO).
Furthermore, methanol has been proposed as a source of hydrogen for
fuel cells.
[0007] Methanol is also called "wood alcohol" because it was
previously produced as a byproduct of the destructive distillation
of wood. It is now mostly produced synthetically by a multi-step
process in which natural gas and steam are reformed in a furnace to
produce hydrogen and carbon monoxide. The hydrogen and carbon
monoxide gases are then reacted under pressure in the presence of a
catalyst to form methanol.
[0008] Biomethanol, i.e. methanol of biological origin can be
produced from various sources. It is typically produced by
anaerobic digestion of biomass such as residues from various
agricultural or forestry crops, waste products of animal and human
effluents, municipal wastes and landfills, sugar beet pulp,
glycerol etc.
[0009] Black liquor formed in the Kraft pulping process has been
proposed as a source for production of biomethanol for use as
non-fossil fuel. In this case, the black liquor is gasified to
produce a mixture of hydrogen and carbon monoxide (synthesis gas)
which is then converted into methanol.
[0010] Biomethanol is also produced as a direct by-product in the
pulping of wood. In the Kraft pulping process, undesired side
reactions of sodium sulphide with various wood constituents result
in the formation of a large number of different organic sulphur
compounds. In the evaporation of the black liquor, a condensate
containing biomethanol is obtained. However, this biomethanol is
contaminated with said sulphur compounds and has a very unpleasant
odour. The contaminated methanol is traditionally incinerated in
the mill to recover its energy content and to destroy the foul
odour components.
[0011] Purification of black liquor derived methanol has been
described in the prior art. Thus, U.S. Pat. No. 5,450,892 discloses
a process for the scrubbing of black liquor condensate stripper
off-gases. The alkaline scrubbing removes gases such as hydrogen
sulphide, methyl mercaptan, dimethyl sulphide and dimethyl
disulphide and allows most of the methanol to remain in the
scrubbed gases. The gases are then incinerated.
[0012] U.S. Pat. No. 5,718,810 discloses a process for the recovery
of methanol from sulphur based wood-pulping processes using
extractive distillation. According to the process, methanol is
recovered from pulping process vapours which contain at least
methanol and dimethyl sulphide. The vapours are distilled in two or
three steps to provide methanol with a purity which may approach
100%.
[0013] In the production of hydrocarbon-based biofuels, the
starting material is typically biomass which is gasified to provide
synthesis gas or syngas. The synthesis gas is then led to a
Fischer-Tropsch (FT) reactor to produce biohydrocarbons. Examples
of suitable biomass sources include forest slash, urban wood waste,
by-products and waste of the papermaking industry, lumber waste,
wood chips, sawdust, straw, firewood, agricultural residue, dung
and the like.
[0014] Gasifiers have been investigated for more than a century,
and many different types have been developed. One drawback of
biomass gasifiers still remains, however, namely their incapacity
to produce a steady synthesis gas flow, having the optimum
H.sub.2/CO ratio of about 2, to be utilized in the most effective
cobalt based Fischer-Tropsch three-phase slurry synthesis. To
correct the hydrogen to carbon monoxide ratio of the synthesis gas
produced from biomass, make-up hydrogen is required.
[0015] Another possibility to produce hydrocarbon-based biofuels is
to use biological triglycerides (bio-oils) or biological fatty
acids (bio-acids) as starting materials. In order to make biofuel,
the starting material is treated by a hydrodeoxygenation process
(HDO). In the catalytic HDO process, hydrogen is combined with
oxygen into water thus releasing the desired paraffinic
biohydrocarbon backbone for chemical manipulation.
[0016] The subsequent phase in the biofuel production after the FT
or HDO process comprises biohydrocarbon product upgrading. The
upgrading processes typically comprise cracking and/or
isomerization processes requiring hydrogen. Advantageously,
one-dimensional molecular sieve catalysts such as Pt/Mordenite,
Pt-SAPO's or Pt-ZSM-23,22 or equivalent are used to get a suitable,
diesel range molecular length of the biohydrocarbon and to provide
a side chain structure determining a desired cloud point and cetane
value. Typically these upgrading processes employ relatively high
hydrogen pressures without any significant hydrogen
consumption.
[0017] Steam reforming of natural gas is the most common method of
producing commercial bulk hydrogen. It is also the least expensive
method. It is based on the idea that at high temperatures
(700-1100.degree. C.) and in the presence of a nickel-based
catalyst, steam reacts with methane to yield hydrogen according to
the equation
CH.sub.4+H.sub.2O .fwdarw.CO+3H.sub.2
[0018] Additional hydrogen can be recovered by a lower-temperature
gas-shift reaction with the carbon monoxide produced.
[0019] Make-up hydrogen can also be produced from the synthesis gas
obtained from the biomass and from tail gases of the biofuel
fractionation. A standard procedure for providing more hydrogen is
the well known water gas shift (WGS) reaction
(CO+H.sub.2O->CO.sub.2+H.sub.2). However, the WGS reaction has
its drawbacks. The WGS reaction is a catalytic process, hard to
control and sensitive to synthesis gas impurities. Moreover,
because the WGS reaction utilizes carbon monoxide, which is part of
the synthesis gas, it lowers the total carbon conversion of the
whole process scheme.
[0020] Thus, there exists a need for providing alternative sources
of hydrogen for the production of biofuels. In order to provide a
100% biological and non-fossil fuel, a biohydrogen product is
needed at reasonable costs. The biohydrogen should preferably be
provided without utilizing carbon monoxide in a WGS reaction, since
carbon monoxide is a component, which makes up the building blocks
of the biohydrocarbon fuel. The present invention strives to
satisfy that need. The present invention provides biohydrogen from
a waste product of the pulp industry, namely from biomethanol.
SUMMARY OF THE INVENTION
[0021] The present invention relates to the use of biomethanol
derived from the pulp industry for the production of biohydrogen.
The biomethanol typically comprises purified biomethanol derived
from spent pulping liquor or black liquor. Biomethanol can be
recovered from the black liquor e.g. by distillation and/or
stripping. The biomethanol is purified before it is used in the
production of biohydrogen. Further purification steps may be
performed on the biohydrogen gas prior to use in the production of
biohydrocarbon fuel.
[0022] In one embodiment, the biohydrogen is used in a biofuel
production facility integrated with a pulp and/or paper mill.
[0023] The present invention also relates to a process for the
production of biohydrogen, wherein crude biomethanol recovered from
black liquor is purified and reformed, where after biohydrogen is
recovered. The purification removes malodorous sulphur impurities
which contaminate crude biomethanol produced in the Kraft pulping
of wood.
[0024] The invention further relates to a process for producing
hydrocarbon biofuel which comprises steps, wherein [0025] a) crude
biomethanol recovered form black liquor is purified and reformed to
provide biohydrogen and purified biohydrogen is recovered; [0026]
b) a biohydrocarbon stream is produced by a process selected from a
Fischer-Tropsch reaction of syngas produced from biomass, a
hydrodeoxygenation of biological triglycerides or fatty acids and
combinations thereof, wherein [0027] c) said biohydrocarbon stream
production of step b) includes at least one process step selected
from adjusting the hydrogen to carbon monoxide ratio of syngas,
cracking/isomerization of Fischer-Tropsch paraffins,
hydrodeoxygenation of said biological triglycerides or fatty acids,
hydroisomerization of n-paraffins, and reduction of catalysts; and
[0028] d) said purified biohydrogen recovered in step a) is used as
a hydrogen source in at least one of the process steps defined in
step c) and the biohydrocarbon stream produced is separated into
fractions and biofuel is recovered from at least one of said
fractions.
[0029] The biomethanol may be reformed together with gaseous
stream(s), which emanate from one or more process steps of the
biofuel production process and which contain gaseous components
capable of forming hydrogen by reforming. The resulting biohydrogen
is typically used directly in the biofuel production.
[0030] The present invention also relates to an integrated
pulp/biofuel production facility, which comprises a Kraft pulp
mill, which provides black liquor; a recovery unit for recovering
of crude biomethanol from said black liquor; a methanol
purification unit for purification of said crude biomethanol to
produce purified biomethanol; a reforming unit for reforming of
said purified biomethanol to produce a gas mixture containing
biohydrogen; a hydrogen purification unit for purification of said
gas mixture to provide purified biohydrogen; and a biofuel
production plant, which produces biohydrocarbon based biofuel from
said biohydrogen and from biomass.
[0031] In one embodiment of the invention, the biomass comprises
biological waste and/or by-products of the Kraft pulp mill such as
forest residue, slash, bark, wood chips, black liquor, tall oil and
tall oil fatty acids, etc. The pulp mill and the biofuel production
plant are preferably integrated by one or more further units.
[0032] An end product of the present invention is biofuel made of
waste and/or by-products of wood processing industry, which biofuel
is made of biohydrocarbon produced from biological waste and/or
by-products of a Kraft pulp mill and biohydrogen produced from
black liquor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 is a schematic diagram of the production of biofuel
using biohydrogen from pulp biomethanol.
[0034] FIG. 2 is a schematic diagram of a production of biohydrogen
from crude biomethanol from a pulping process.
[0035] FIG. 3 is a schematic diagram of the use of biohydrogen
produced in a pulp mill integrated with a biofuel production
plant.
DETAILED DESCRIPTION OF THE INVENTION
[0036] The present invention relates to the production of
biohydrogen for use in the production of biofuel. In one
embodiment, the invention relates an integrated industrial concept,
wherein a biofuel production plant utilizes the biological waste
and/or by-products of an adjacent pulp mill for the production of
valuable biofuel which can replace fossil fuels.
[0037] In the present specification and claims, the following terms
have the meanings defined below.
[0038] The term "biomethanol" refers to methanol CH.sub.3OH
produced from biological sources, that is from renewable biological
(non-fossil) sources. Typically the biomethanol of the present
invention is produced from spent pulping liquor (black liquor).
[0039] The terms "biohydrogen" and "biohydrocarbon" refer to
hydrogen and to hydrocarbon, respectively, produced from biological
sources, i.e. from renewable biological (non-fossil) sources.
[0040] The terms "biological", "biomaterial" and "biological
origin" refer to a wide variety of materials derived from plants,
animals and/or fish, i.e. from biorenewable sources as opposed to
fossil sources.
[0041] The term "biomass" includes any kind of material of
biological origin which is suitable for being gasified for
producing synthesis gas and/or which contains triglycerides and/or
fatty acids suitable for the production of hydrocarbons. The
biomass is typically selected from virgin and waste materials of
plant, animal and/or fish origin, such as municipal waste,
industrial waste or by-products, agricultural waste or by-products
(including also dung), waste or by-products of the wood-processing
industry, waste or by-products of the food industry, marine plants
(such as algae) and combinations thereof. The biomass material is
preferably selected from non-edible resources such as non-edible
wastes and non-edible plant materials, including oils, fats and
waxes.
[0042] A specific biomass material according to the present
specification and claims comprises "biological waste and/or by
products of wood-processing industry". This wood-derived biomass
includes forest residues, wood slash, bark, urban wood waste,
lumber waste, wood chips, sawdust, straw, firewood, wood materials,
paper, pulp, by-products of the papermaking or timber processes,
black liquor, tall oil and tall oil fatty acids, etc.
[0043] The term "wood-processing industry" refers to any kind of
industry that uses wood as its raw material. Typical
wood-processing industries comprise pulp and paper mills, saw
mills, panel board companies, fire-wood producers, wood
pelletizers, etc.
[0044] The term "biological waste and/or by-products of a Kraft
pulp mill" refers to any biological waste and/or by-products which
are created in connection with a Kraft pulping process and which
can be used in the production of hydrocarbons. The term refers
typically to forest residue, slash, bark, wood chips and black
liquor as well as to tall oil and tall oil fatty acids.
[0045] The term "biofuel" refers to fuel produced mainly or wholly
from biological sources. The biofuels of the present invention are
practically free of oxygen.
[0046] The term "biodiesel" refers in this specification only to
those traditional biological fuel products which are produced from
trans-esterification of biomass-derived oils with alcohol and which
contain oxygen.
[0047] The "spent pulping liquor" or "black liquor" is an aqueous
solution of lignin residues, hemicellulose, and the inorganic
chemicals used in a Kraft pulping process.
[0048] The term "middle distillate" refers to a hydrocarbon
fraction, wherein the hydrocarbons consist essentially of
hydrocarbons typically having a carbon chain length of 11 to
20.
[0049] The term "heavy fraction" refers to a hydrocarbon fraction,
wherein the hydrocarbons consist essentially of hydrocarbons having
a carbon chain length above 20.
[0050] The term "naphtha fraction" refers to a distilled
hydrocarbon fraction, wherein the hydrocarbons consist essentially
of hydrocarbons having a carbon chain length of 5 to 10.
[0051] The term "light fraction" refers to a hydrocarbon fraction,
wherein the hydrocarbon chain length is 1 to 4. The light fraction
also includes other gaseous components such as hydrogen and carbon
monoxide, depending on the process from which the light fraction
derives.
[0052] The term "synthesis gas" or "syngas" refers to a gas mixture
that contains varying amounts of carbon monoxide and hydrogen
generated by the gasification of a carbon containing substance.
Gasification of biological materials provides a ratio of hydrogen
to carbon monoxide, which is close to 2. The gas is suitable for
providing hydrocarbons by the Fischer-Tropsch synthesis after some
additional hydrogen has been added.
[0053] The term "biomass-to-liquid" BTL refers to a multi step
process to produce liquid biofuels from biomass. The process uses
the whole plant to improve the CO.sub.2 balance and increase yield.
The main process used for BTL is the Fischer-Tropsch process.
[0054] The "Fischer-Tropsch" (FT) synthesis is a catalyzed chemical
reaction in which hydrogen and carbon monoxide (synthesis gas) are
converted to a substantially Gaussian distribution of hydrocarbon
chains of various lengths. Typical catalysts used are based on iron
and cobalt.
[0055] The "catalytic hydrodeoxygenation" (HDO) used in the present
specification and claims refers to a catalytic treatment of the
biological triglyceride (oil, fat, wax) and/or fatty acid feed with
hydrogen under catalytic conditions, wherein the following
reactions take place: breaking down of the triglyceride structure,
deoxygenation or removal of oxygen as water, and hydrogenation to
saturate double bonds. The preferred HDO of the invention also
removes non-desired impurities such as sulphur as hydrogen sulfide
and nitrogen as ammonia. Useful HDO catalysts are, for instance,
those mentioned in U.S. Pat. No. 7,232,935 as suitable for the HDO
step described therein.
[0056] The terms "isomerization" and "hydroisomerization" refer to
the catalytic and hydrogen assisted introduction of short chain
(typically methyl) branches into n-paraffinic hydrocarbons.
[0057] The term "non-cracking hydroisomerization", which is used
for the HDO hydrocarbon stream of the present invention, refers to
an isomerization performed with a catalyst known to have little or
no effect on cracking of the hydrocarbons in question. Typical
non-cracking catalysts comprise intermediate pore size
silicoaluminophosphate molecular sieve (SAPO) catalysts. Useful
non-cracking isomerization catalysts are, for instance, those
mentioned in U.S. Pat. No. 7,232,935 for the isomerization step
described therein.
[0058] The term "catalytic cracking/isomerization", which is used
for the FT produced paraffins according to the present invention
refers to a simultaneous cracking and hydroisomerization step
occurring according to the so called carbocation mechanism (G. A.
Olah et al., Superacids, Wiley-Interscience, 1985, Chapter 5).
Typical isomerization catalysts have both
hydrogenation-dehydrogenation (Pt, Pd) and acidic functions
(molecular sieves). The process is performed in the presence of
hydrogen with a catalyst known to have both cracking and
isomerizing properties. Typical cracking/isomerizing catalysts
include ZSM zeolite catalyst such as the ZSM-5 and ZSM-23 catalysts
described U.S. Pat. Nos. 4,222,855, 4,229,282 and 4,247,388 for use
in selective cracking and isomerization of a paraffinic feedstock
such as a Fischer-Tropsch wax.
[0059] The term "autothermal reforming" (ATR) refers to the
catalytic production of hydrogen from feed stocks such as
hydrocarbons and methanol by the combination of partial oxidation
and steam reforming.
[0060] The term "water gas shift" (WGS) refers to the inorganic
chemical reaction in which water and carbon monoxide react to form
carbon dioxide and hydrogen (water splitting).
[0061] The term "recovery" as used in connection with biomethanol
and biohydrogen in the present specification and claims does not
necessarily imply that the methanol or hydrogen in question is
separated out into a product of its own. The term also applies to
the direct use of the obtained methanol or hydrogen, respectively,
in a subsequent process.
[0062] An "integrated process" means a process wherein two or more
related functions, which can be separately performed, are combined
so that at least one significant process step is common for the two
processes.
[0063] The term "cetane number" or "cetane value" relates to the
ignition quality of diesel fuel. It is a value obtained by a
standardized comparison of the fuel under analysis with fuels or
blends with a known cetane number. The reference fuel n-cetane
(C.sub.16) has the cetane number 100.
[0064] The embodiment, which is of particular interest for the
present invention, relates to the recovery of methanol from black
liquor. The crude biomethanol may be recovered by stripping and/or
distilling of the black liquor, or it may be recovered as a
by-product in the distillation of tall oil, which is produced via
acidulation of the black liquor.
[0065] The biomethanol is a low value side product of pulp
production and it has typically been burned for energy. According
to the present invention, however, biomethanol derived from black
liquor is used as a source for bio-hydrogen for the FT and/or HDO
processes via a reforming process.
[0066] Biomethanol derived from black liquor contains a number of
nitrogen and sulphur compounds originating from pulping process
chemicals. Some nitrogen compounds also originate from the
de-amination of wood proteins during the pulping process.
[0067] The various compounds, especially the nitrogen and sulphur
compounds, included in crude biomethanol may harm the conversion
catalysts used in the production of the biofuel and extra
purification steps are needed to make the biomethanol sulphur free
for the catalytic steps.
[0068] The crude biomethanol may be purified by process steps such
as washing, scrubbing, stripping, liquid-liquid separation,
distillation, catalytic conversion, ion exchange, absorption and
adsorption. Special adsorbents, ion-exchangers, catalysts and
cleaning devices are available on the market.
[0069] It has been found that ammonia is the most abundant among
the nitrogen compounds and that sulfides such as hydrogen sulphide,
dimethyl sulphide, dimethyl disulphide and methanethiol are the
most abundant among the sulphur compounds. All of these compounds
are gases or low boiling liquids, and they are removable by
stripping and/or distilling. The biomethanol also contains thiol
compounds, which have a mercapto group (--SH) in their molecules.
These are considered as being responsible for the undesirable smell
of the pulp biomethanol. The stripped and/or distilled biomethanol
still contains some higher molecular weight impurities, which are
removed e.g. by adsorption. Suitable adsorbents are available on
market. At need, combinations of adsorbents, washers, catalysts,
etc. may be used.
[0070] For instance, ZnO based adsorbent materials are able to
adsorb organic sulphur compounds and can be used to purify
biomethanol to an acceptable level. Some sulphur compounds and
especially carbon dioxide may be removed by a purification process,
which includes subjecting the crude biomethanol stream to
refrigerated methanol at a high pressure. The refrigerated methanol
acts as a physical solvent and absorbs impurities from the
biomethanol. The absorbed impurities are subsequently removed from
the physical solvent by lowering the pressure and/or steam
stripping. Solvents which rely on chemical reactions to remove
impurities and catalysts which degrade impurities can also be used
to purify the biomethanol used in the present invention. The
processes outlined in U.S. Pat. Nos. 5,450,892 and 5,718,810
mentioned above, may also be used in the purification of the
biomethanol of the present invention. Combinations of different
purification processes provide the best results.
[0071] The purified biomethanol may still contain some high
molecular weight sulphur and nitrogen compounds. These compounds
will pass into the reformer with the methanol and will degrade
there to smaller compounds, finally to ammonia and hydrogen
sulphide, which pressure swing adsorption (PSA) molecular sieve
adsorbents are capable of adsorbing.
[0072] The purified biomethanol is subjected to reforming,
typically in an autothermal reforming (ATR) process. Also steam
reforming with a separate heat source may be used. The ATR
converting unit is a technology which is known as such to those
skilled in the art and available in the markets. The principles of
steam reforming are also known to those skilled in the art.
[0073] It is well known in the art that methanol can be reformed to
hydrogen by various methods other than autothermal reforming.
However, since reforming is an endothermic reaction, it will need
an outside energy source to be able to maintain the reaction.
Unless cheap outside fuel is available, it is reasonable to utilize
part of the feed methanol as a fuel to maintain the optimal
reaction temperature for reforming, providing autonomous
reforming.
[0074] Autothermal reforming of methanol is a combination of
exothermic partial oxidation of methanol and endothermic water gas
shift of carbon monoxide producing carbon dioxide and hydrogen.
4CH.sub.3OH+3H.sub.2O.fwdarw.4CO.sub.2+11H.sub.2
[0075] The idea was developed in the late 1980s by Johnson-Matthey
and it has a net reaction enthalpy change of zero. As a
consequence, a reactor for this process does not require external
heating once having reached reaction temperature. The maximum
obtainable hydrogen content in the product gas is 65% using the
stoichiometry at 300.degree. C.
[0076] After reforming, the resulting biohydrogen is suitably
further purified and separated from the produced CO.sub.2. A
pressure swing adsorption (PSA) unit or the like means is suitably
used for the purification and separation. The resulting purified
biohydrogen is ready for further use.
[0077] The biohydrogen produced from the black liquor is
advantageously utilized in a process for producing hydrocarbon
biofuel.
[0078] The biohydrocarbon for the biofuel may be produced either by
a Fischer-Tropsch (FT) reaction of synthesis gas produced by
gasification of biomass or by hydrodeoxygenation (HDO) of
biological triglycerides or fatty acids. The biohydrocarbon may of
course also be blended from hydrocarbons produced by both process
types.
[0079] The biomass material for the gasification may be any biomass
material suitable for the production of synthesis gas. In a
preferred embodiment of the present invention the biomass comprises
biological waste and/or by-products of wood-processing industry. In
an embodiment of the invention, the wood-processing industry
comprises a Kraft pulp mill and the biomass comprises biological
waste and/or by-products of the mill.
[0080] After gasification of the biomass feedstock an FT reaction
is used to produce hydrocarbons from the hydrogen and carbon
monoxide of the synthesis gas. The biohydrogen produced from the
biomethanol according to the invention is used to adjust the
H.sub.2 to CO ratio of the produced synthesis gas to about 2, which
is suitable for the FT reaction. The reaction provides
biohydrocarbons having varying chain lengths.
[0081] After removal of off-gases, the remaining biohydrocarbons
are subjected to cracking/isomerization to shorten the chain
lengths. In this reaction the biohydrogen of the invention may
again be used to provide a sufficient hydrogen pressure. The
cracking increases the proportion of C.sub.11--C.sub.20 paraffins
in the biohydrocarbon stream. At the same time, the isomerization
provides branched hydrocarbons which improve the cloud point of the
end product fuel.
[0082] The biomass for the hydrodeoxygenation (HDO) process may be
any triglyceride or fatty acid material, which is suitable for the
production of hydrocarbons by the HDO process. Such material
typically comprises non-edible oils such as jatropha oil, castor
oil, tall oil or tall oil fatty acids (TOFA), etc. In a preferred
embodiment of the present invention, the biomass comprises a
biological by-product of wood processing industry, such as tall oil
or tall oil fatty acids. The biohydrogen produced from the
biomethanol may be used in the HDO process, which provides a stream
of saturated n-paraffins rich in biohydrocarbons with 16 and 18
carbon chains.
[0083] The HDO treatment also saturates any unsaturated chains. The
n-paraffins are typically hydroisomerized to increase the
proportion of i-paraffins in the biohydrocarbon stream. The
biohydrogen of the present invention provides a suitable hydrogen
feed to provide the required hydrogen pressure for the non-cracking
hydroisomerization catalyst. The hydroisomerization may be
performed in a separate isomerization reactor or it may be
performed in the same reactor with the hydrodeoxygenation.
[0084] From time to time the catalysts used in the biofuel
production process steps need to be regenerated by reduction with
hydrogen. This may also be performed using the biohydrogen of the
present invention. The role of the hydrogen catalyst regeneration
is twofold: firstly, to reduce the active metal back to the zero
valent metallic state, and secondly, to flush out the heavy wax
components eventually blocking the catalyst system.
[0085] The hydrogenated and/or isomerized biohydrocarbon stream(s)
from the FT and/or HDO processes is/are subsequently separated into
fractions suitable for biofuel use. Typical fractions include a
light fraction, a naphtha fraction, a middle distillate fraction
and a heavy fraction. The middle distillate comprises a desirable
hydrocarbon biofuel since it has an ideal boiling point range, a
good cetane value and cloud point, and it can replace fossil diesel
fuel.
[0086] In an advantageous embodiment of the invention, the biofuel
production facility is integrated with a pulp and/or paper mill. In
such a case, biological waste and/or by-products of the mill are
suitably used as biomass for gasification to syngas. When the mill
comprises a Kraft pulp mill, black liquor typically serves as a
source for the biomethanol and tall oil or tall oil fatty acids may
serve as feedstock for a HDO process.
[0087] A typical integrated pulp/biofuel production facility
comprises a Kraft pulp mill, which provides black liquor containing
biomethanol. The integrated facility includes units for recovery,
purification and reforming of said biomethanol and units for
purification and recovery of the produced biohydrogen. A biofuel
production plant is provided, which produces biohydrocarbon based
fuel from the biohydrogen and from biomass comprising biological
waste and/or by-products of the Kraft pulp mill.
[0088] The biomethanol recovery unit includes one or more stripping
units and/or distillation units for the recovery of crude
biomethanol. Since the pulp biomethanol has a foul smell and
contains impurities which may harm the catalysts, various units may
be provided for purification of the crude biomethanol. These
include means selected from a scrubbing unit, a washing unit, a
stripping unit, an adsorbing unit, an absorbing unit, a catalytic
reactor unit, and combinations thereof.
[0089] After purification, the biomethanol is reformed to produce
hydrogen. The most advantageous reforming unit is an autothermal
reforming unit, although a steam reforming unit may also be
used.
[0090] The gas produced in the reformer includes impurities, that
is, other gases besides biohydrogen, and the plant accordingly
includes means for purification of the biohydrogen. The hydrogen
purification unit typically includes a pressure swing adsorbing
unit (PSA), which is capable of providing pressurized and purified
biohydrogen.
[0091] The biofuel or BTL plant of the inventive biofuel facility
is of a well known design, comprising either an FT or a HDO reactor
or both. The separation and recovery of the biofuel is performed in
a well known manner.
[0092] According to an embodiment of the invention a biofuel
product is made of waste and/or by-products of wood processing
industry. The biofuel is advantageously made of biohydrocarbons
produced from biological waste and/or by-products of a Kraft pulp
mill and biohydrogen produced from biomethanol from black
liquor.
[0093] The following examples are given to further illustrate the
invention and are not intended to limit the scope thereof.
Example 1
[0094] FIG. 1 shows a schematic flow diagram of a biomass-to-liquid
(BTL) process located in close connection to and integrated with a
Kraft pulp and paper mill (not shown). The BTL process produces
biofuel using biohydrogen derived from pulp biomethanol.
[0095] The biomass-to-liquid process comprises feeding of biomass 1
to a feed stock pretreatment unit 2, where after the feed stock is
led to a gasification and gas conditioning unit 3 for synthesis gas
production. The gasification and gas conditioning unit 3 includes
i.a. scrubbing of the gas and a water gas shift (WGS) unit. The
unit 3 is connected to an air separation unit (ASU) 4 for
production of oxygen. Before the Fischer-Tropsch (FT) synthesis
unit 6, the gas is treated in a gas processing and clean-up unit
5.
[0096] Biohydrogen is produced in an autothermal reforming (ATR)
unit 7 from purified biomethanol 16 recovered from the Kraft pulp
mill. Also tail gases 14 and off-gases 15 from the BTL process are
fed to the ATR unit 7 for reforming. The resulting biohydrogen is
purified and separated out in a pressure swing adsorption (PSA)
unit 8. The purified biohydrogen is fed to the FT synthesis unit 6
to adjust the H.sub.2 to CO ratio of the reacting gas to about
2.
[0097] The product gas of the FT synthesis unit 6 is led to a
product upgrade unit 11. FT tail gases 14 and off-gases 15 are
removed from the FT synthesis unit 6 and product upgrade unit 11,
respectively, and directed to the ATR unit 7. Naphtha 9 and middle
distillate 10 fractions are obtained as fractions of the FT product
gas from upgrade unit 11.
Example 2
[0098] Biohydrogen is produced from crude biomethanol recovered
from a Kraft pulping process in accordance with the diagram shown
in FIG. 2.
[0099] Crude biomethanol produced in the Kraft pulping process is
distilled and/or stripped in recovery unit 12 and is introduced
into a methanol purification unit 13 that is capable of removing
sulphur compounds. In the shown embodiment, the purification unit
13 comprises two adsorbers, each containing an adsorbent bed. The
adsorbers are used alternately, one being in use, while the other
is regenerated. Further purification means such as scrubbers,
washers, absorbers, and catalytic reactors may be added at
need.
[0100] The purified biomethanol is directed to an autothermal
reforming unit (ATR) 7, to which also air is introduced. The ATR
unit 7 produces a gas mixture containing biohydrogen, carbon
dioxide, nitrogen, ammonia and hydrogen sulphide. The gas also
contains minor amounts of higher molecular weight sulphur compounds
of a malodorous nature. The gas mixture is mixed with recirculated
biohydrogen H.sub.2 and then directed to a hydrogen purification
unit 8 comprising a pressure swing adsorber (PSA) bank. The gas is
purified in the adsorbents, and pressurized biohydrogen 17 having a
purity above 99% is recovered.
Example 3
[0101] FIG. 3 is a schematic flow diagram of the use of biohydrogen
produced in a Kraft pulp mill 19 integrated with a biofuel
production plant 20.
[0102] Wood for the pulp mill 19 is procured and handled in wood
logistics facility 18 for use as raw material in the production of
pulp. Bark recovered in the wood handling of the facility 18 is
incinerated in the boiler (not shown) of the pulp mill 19 for
energy production. Energy wood (mainly forest residue) 1 from the
common wood logistics facility 18 is fed to the biomass-to-liquid
(BTL) plant 20.
[0103] In this example about 2.1 TWh/a (terawatt hours/annum) or
about 1 Mio m.sup.3/a (millions of cubic meter/annum) of forest
residue is fed to the BTL plant 20. The BTL process produces
65,000-88,000 t/a (metric ton/annum) of middle distillate and
20,000-27,000 t/a of naphtha. The Kraft pulp process produces about
600,000-700,000 t/a pulp.
[0104] The Kraft pulp mill 19 produces black liquor from which
about 20,000 t/a crude biomethanol is recovered in recovery unit 12
by stripping and distilling. The crude pulp biomethanol is
pre-purified in absorbers 13 and all or a part thereof is directed
to an ATR unit of the BTL plant 20 to provide make-up biohydrogen,
when the hydrogen created within the BTL process is
insufficient.
[0105] The integrated pulp/paper mill 19 and BTL plant 20 will
advantageously also have other integrated processes in addition to
the above mentioned wood raw material and biomethanol feeds. Thus,
steam, power, gas and water may be transported between the
processes and/or may be handled in an integrated devices. FIG. 3
shows as an example of further integration an integrated water
purification facility 21. In this case, the BTL process uses a
cobalt catalyst in its Fischer-Tropsch synthesis and, consequently,
alcohol-contaminated water is produced in the BTL process. The
contaminated water is diluted with water from the pulp and paper
mill 19 and then treated in a common biological purification
process unit 21. Contaminated water from the pulp and paper mill 19
is purified in the same waste water purification unit 21.
[0106] The present invention has been described herein with
reference to specific embodiments. It is however clear to those
skilled in the art that the process(es) may be varied within the
bounds of the claims.
* * * * *