U.S. patent application number 13/347514 was filed with the patent office on 2012-11-29 for systems and methods for soda ash production.
Invention is credited to Betty Kong Ling Pun, RIYAZ SHIPCHANDLER, Michael Joseph Weiss.
Application Number | 20120298522 13/347514 |
Document ID | / |
Family ID | 46507411 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120298522 |
Kind Code |
A1 |
SHIPCHANDLER; RIYAZ ; et
al. |
November 29, 2012 |
SYSTEMS AND METHODS FOR SODA ASH PRODUCTION
Abstract
Provided herein are methods and systems to produce sodium
carbonate (soda ash). The methods and systems provided herein
modify a Solvay process by integrating it with an electrochemical
process to produce a less carbon dioxide intensive Solvay process
and an environmentally friendly sodium carbonate product.
Inventors: |
SHIPCHANDLER; RIYAZ;
(Campbell, CA) ; Pun; Betty Kong Ling; (San Jose,
CA) ; Weiss; Michael Joseph; (Los Gatos, CA) |
Family ID: |
46507411 |
Appl. No.: |
13/347514 |
Filed: |
January 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61431767 |
Jan 11, 2011 |
|
|
|
61446482 |
Feb 24, 2011 |
|
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Current U.S.
Class: |
205/482 ;
204/275.1 |
Current CPC
Class: |
C25B 1/00 20130101; C25B
15/08 20130101 |
Class at
Publication: |
205/482 ;
204/275.1 |
International
Class: |
C25B 1/14 20060101
C25B001/14; C25B 15/00 20060101 C25B015/00; C25B 9/00 20060101
C25B009/00 |
Claims
1. A method to produce sodium carbonate, comprising: a) absorbing
carbon dioxide in an ammonia solution to form sodium bicarbonate;
and b) subjecting the sodium bicarbonate to a first electrochemical
process to produce sodium carbonate.
2. A method to modify a Solvay process to produce a less carbon
dioxide intensive Solvay process, comprising: a) absorbing carbon
dioxide in an ammonia solution to form sodium bicarbonate; and b)
subjecting the sodium bicarbonate to a first electrochemical
process to produce sodium carbonate, thereby resulting in a less
carbon dioxide intensive Solvay process.
3. The method of claim 1 or 2, further comprising regenerating the
ammonia solution using calcium oxide obtained by lime
calcination.
4. The method of claim 1 or 2, further comprising regenerating the
ammonia solution using sodium hydroxide obtained from the first or
a second electrochemical process.
5. The method of claim 1 or 2, wherein the method does not comprise
bicarbonate calcination, lime calcination, or a combination
thereof.
6. The method of claim 1 or 2, wherein the method produces less
than 80% carbon dioxide as compared to a conventional Solvay
process.
7. The method of claim 1 or 2, further comprising treating the
sodium carbonate with calcium or magnesium ions to form calcium
carbonate, magnesium carbonate, or combination thereof.
8. The method of claim 7, wherein the calcium carbonate, magnesium
carbonate, or combination thereof is a cementitious material.
9. The method of claim 8, wherein the cementitious material
comprises vaterite.
10. The method of claim 8, wherein the cementitious material has a
compressive strength of greater than 10 MPa.
11. A system comprising a Solvay system integrated with an
electrochemical system, comprising: a) a Solvay system comprising
an absorber configured to absorb carbon dioxide in an ammonia
solution to form sodium bicarbonate; and b) a first electrochemical
system operably connected to the Solvay system configured to
convert the sodium bicarbonate to sodium carbonate.
12. The system of claim 11, further comprising a regenerator
operably connected to the Solvay system configured to regenerate
the ammonia solution after absorption of the carbon dioxide in the
ammonia solution.
13. The system of claim 12, further comprising a lime calciner
operably connected to the regenerator and configured to produce
calcium oxide for regenerating the ammonia solution.
14. The system of claim 12, further comprising a second
electrochemical system operably connected to the regenerator and
configured to produce sodium hydroxide for regenerating the ammonia
solution.
15. The system of claim 11, further comprising a precipitator
operably connected to the first electrochemical system configured
to produce calcium and/or magnesium carbonate by treating sodium
carbonate with calcium and/or magnesium ions.
Description
CROSS-REFERENCE
[0001] This application claims priority to U.S. Provisional
Application No. 61/431,767, filed Jan. 11, 2011 and U.S.
Provisional Application No. 61/446,482, filed Feb. 24, 2011, both
of which are incorporated herein by reference in their entireties.
This application is related to the following patent applications:
U.S. Provisional Patent Application No. 61/081,299, filed 16 Jul.
2008, titled "Low Energy pH Modulation for Carbon Sequestration
Using Hydrogen Absorptive Metal Catalysts"; U.S. Provisional Patent
Application No. 61/091,729, filed 25 Aug. 2008, titled "Low Energy
Absorption of Hydrogen Ion from an Electrolyte Solution into a
Solid Material"; U.S. Provisional Patent Application No.
61/222,456, filed 1 Jul. 2009, titled "CO.sub.2 Utilization In
Electrochemical Systems"; and PCT Patent Application No.
PCT/US09/48511, filed on 25 Jun. 2009, titled "Low Energy 4-Cell
Electrochemical System with Carbon Dioxide Gas," each of which is
incorporated herein by references in its entirety.
BACKGROUND
[0002] The Solvay process, also referred to as the ammonia-soda
process, is an industrial process for production of soda ash
(sodium carbonate). The ingredients for this process may be readily
available: salt brine (from inland sources or from the sea) and
limestone (from mines). Carbon dioxide is emitted from the use of
soda ash, and is emitted during production of soda ash, depending
on the industrial process used to manufacture soda ash. There is a
need for systems and methods for production of soda ash in a less
carbon dioxide-intensive manner.
SUMMARY
[0003] Provided herein is a novel and non-obvious process, machine,
manufacture, and composition thereof.
[0004] In one aspect, there is provided a method to produce sodium
carbonate, comprising: a) absorbing carbon dioxide in an ammonia
solution to form sodium bicarbonate; and b) subjecting the sodium
bicarbonate to a first electrochemical process to produce sodium
carbonate. In one aspect, there is provided a method to modify a
Solvay process to produce a less carbon dioxide intensive Solvay
process, comprising: a) absorbing carbon dioxide in an ammonia
solution to form sodium bicarbonate; and b) subjecting the sodium
bicarbonate to a first electrochemical process to produce sodium
carbonate, thereby resulting in a less carbon dioxide intensive
Solvay process. In some embodiments of these aspects, the method
further comprises regenerating the ammonia solution using calcium
oxide obtained by lime calcination. In some embodiments of these
aspects, the method further comprises regenerating the ammonia
solution using sodium hydroxide obtained from the first or a second
electrochemical process. In some embodiments of these aspects, the
method does not comprise bicarbonate calcination, lime calcination,
or a combination thereof. In some embodiments of these aspects, the
method produces less than 80% carbon dioxide as compared to a
conventional Solvay process. In some embodiments of these aspects,
the method further comprises treating the sodium carbonate with
calcium or magnesium ions to form calcium carbonate, magnesium
carbonate, or combination thereof. In some embodiments, the calcium
carbonate, magnesium carbonate, or combination thereof is a
cementitious material. In some embodiments, the cementitious
material comprises vaterite. In some embodiments, the cementitious
material has a compressive strength of greater than 10 MPa.
[0005] In one aspect, there is provided a system comprising a
Solvay system integrated with an electrochemical system,
comprising: a) a Solvay system comprising an absorber configured to
absorb carbon dioxide in an ammonia solution to form sodium
bicarbonate; and b) a first electrochemical system operably
connected to the Solvay system configured to convert the sodium
bicarbonate to sodium carbonate. In some embodiments of the
systems, the system further comprises a regenerator operably
connected to the Solvay system configured to regenerate the ammonia
solution after absorption of the carbon dioxide in the ammonia
solution. In some embodiments of the systems, the system further
comprises a lime calciner operably connected to the regenerator and
configured to produce calcium oxide for regenerating the ammonia
solution. In some embodiments of the systems, the system further
comprises a second electrochemical system operably connected to the
regenerator and configured to produce sodium hydroxide for
regenerating the ammonia solution. In some embodiments of the
systems, the system further comprises a precipitator operably
connected to the first electrochemical system configured to produce
calcium and/or magnesium carbonate by treating sodium carbonate
with calcium and/or magnesium ions.
DRAWINGS
[0006] The novel features of the invention are set forth with
particularity in the appended claims. A better understanding of the
features and advantages of the invention will be obtained by
reference to the following detailed description that sets forth
illustrative embodiments, in which the principles of the invention
are utilized, and the accompanying drawings of which:
[0007] FIG. 1 provides the Solvay process for preparing soda
ash.
[0008] FIG. 2 is an illustrative embodiment of a modification of
the Solvay process incorporating electrochemical process.
[0009] FIG. 3 is an illustrative embodiment of another modification
of the Solvay process incorporating electrochemical process.
[0010] FIG. 4 is an illustrative embodiment of yet another
modification of the Solvay process incorporating two
electrochemical processes.
[0011] FIG. 5 is an illustrative embodiment of a process for
producing soda ash from direct capture of carbon dioxide.
[0012] FIG. 6 is an illustrative embodiment of a comparison of
carbon dioxide emissions from the processes illustrated in FIGS.
1-5.
[0013] FIG. 7 is an illustrative embodiment of a process for
producing soda ash from alkaline brines in accordance with the
existing process by Searles Valley Minerals (Overland Park,
Kans.).
[0014] FIG. 8 is an illustrative embodiment of a modification of
the Searles Valley Minerals process incorporating electrochemical
process.
[0015] FIG. 9 is an illustrative embodiment of a process for
producing soda ash from alkaline brines incorporating
electrochemical process.
[0016] FIG. 10 is an illustrative embodiment of a comparison of
carbon dioxide emissions from the processes provided in FIGS. 7-9
and a direct capture of carbon dioxide.
[0017] FIG. 11 is an illustrative embodiment of a typical process
for converting trona to soda ash.
[0018] FIG. 12 is an illustrative embodiment of a process for
producing soda ash from trona utilizing electrochemical
process.
[0019] FIG. 13 provides an illustrative embodiment of an
electrochemical system.
[0020] FIG. 14 provides an illustrative embodiment of an
electrochemical system.
[0021] FIG. 15 provides an illustrative embodiment of an
electrochemical system.
[0022] FIG. 16 provides an illustrative embodiment of an
electrochemical system.
[0023] FIG. 17 provides an illustrative embodiment of a Solvay
system integrated with the electrochemical system.
[0024] FIG. 18 provides an illustrative embodiment of a processing
system.
[0025] FIG. 19 illustrates a plot comparing the performance between
10 wt % NaOH and 1 mol/L sodium bicarbonate solution in an
electrochemical cell.
DESCRIPTION
[0026] Described herein are methods and systems to produce sodium
carbonate by integrating Solvay process with electrochemical
processes. The methods and systems provided herein are devoid of
calcination of bicarbonate and lime as found in a conventional
Solvay process, thereby providing a less carbon dioxide intensive
Solvay process and an environmentally friendly sodium carbonate
product.
[0027] It is to be understood that the invention is not limited to
particular embodiments described herein as such embodiments may
vary. It is also to be understood that the terminology used herein
is for the purpose of describing particular embodiments only, and
is not intended to be limiting, since the scope of the invention
will be limited only by the appended claims. Unless defined
otherwise, all technical and scientific terms used herein have the
same meaning as commonly understood by one of ordinary skill in the
art to which this invention belongs.
[0028] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limit of that range and any other stated or intervening
value in that stated range, is encompassed. The upper and lower
limits of these smaller ranges may independently be included in the
smaller ranges and are also encompassed, subject to any
specifically excluded limit in the stated range. Where the stated
range includes one or both of the limits, ranges excluding either
or both of those included limits are also included.
[0029] Certain ranges are presented herein with numerical values
being preceded by the term "about." The term "about" is used herein
to provide literal support for the exact number that it precedes,
as well as a number that is near to or approximately the number
that the term precedes. In determining whether a number is near to
or approximately a specifically recited number, the near or
approximating unrecited number may be a number, which, in the
context in which it is presented, provides the substantial
equivalent of the specifically recited number.
[0030] All publications, patents, and patent applications cited in
this specification are incorporated herein by reference to the same
extent as if each individual publication, patent, or patent
application were specifically and individually indicated to be
incorporated by reference. Furthermore, each cited publication,
patent, or patent application is incorporated herein by reference
to disclose and describe the subject matter in connection with
which the publications are cited. The citation of any publication
is for its disclosure prior to the filing date and should not be
construed as an admission that the claimed invention is not
entitled to antedate such publication by virtue of prior invention.
Further, the dates of publication provided may be different from
the actual publication dates, which may need to be independently
confirmed.
[0031] It is noted that, as used herein and in the appended claims,
the singular forms "a," "an," and "the" include plural references
unless the context clearly dictates otherwise. It is further noted
that the claims may be drafted to exclude any optional element. As
such, this statement is intended to serve as antecedent basis for
use of such exclusive terminology as "solely," "only" and the like
in connection with the recitation of claim elements, or use of a
"negative" limitation.
[0032] As will be apparent to those of skill in the art upon
reading this disclosure, each of the individual embodiments
described and illustrated herein has discrete components and
features which may be readily separated from or combined with the
features of any of the other several embodiments. Any recited
method can be carried out in the order of events recited or in any
other order, which is logically possible. Although any methods and
materials similar or equivalent to those described herein may also
be used in the practice or testing of the invention, representative
illustrative methods and materials are now described.
Methods and Systems
[0033] A "Solvay process," as used herein, includes any process
that can be used to produce sodium carbonate using ammonia and
carbon dioxide. About 25 percent of the world production of soda
ash may be from natural sodium carbonate bearing deposits referred
to as natural processes. For example, during the natural production
process, trona (a principal ore from which natural soda ash may be
made) may be calcined in a rotary kiln and chemically transformed
into a crude soda ash. However, carbon dioxide is generated in the
process. In the Solvay process, as illustrated in FIG. 1, sodium
chloride brine, limestone, coke and ammonia are the raw materials
in a series of reactions leading to the production of soda ash.
Ammonia may be regenerated while a small amount may be lost. From
the series of reactions illustrated in FIG. 1, CO.sub.2 is
generated in two calcination processes. The CO.sub.2 generated may
be captured, compressed and directed to Solvay precipitating towers
for consumption in a mixture of brine (aqueous NaCl) and ammonia.
However, there is net CO.sub.2 emitted to the atmosphere during the
production of soda ash because more CO.sub.2 is produced by
calcining limestone than is stoichiometrically required for
absorption. The methods and systems described herein are related to
the reduction of the CO.sub.2 emission from the Solvay process by
eliminating one or both of the calcining steps. The calcining steps
of the Solvay process may be replaced by the electrochemical
processes described herein.
[0034] The Solvay process (as illustrated in FIG. 1) benefits from
modifications comprising one or more elements of the processing
and/or electrochemical systems and methods described herein. In
some embodiments, for example, some of the carbon dioxide emitted
from the Solvay process may be processed in accordance with any of
the CO.sub.2-processing methods described herein. In such
embodiments, the carbon dioxide may originate from Reaction IV
("Bicarb Calcination"), Reaction II ("Lime Calcination"), or a
combination thereof. In addition, calcium chloride, which is
produced in Reaction III ("Regeneration") in FIG. 1, may be used in
some embodiments to produce calcium and/or magnesium carbonates
(e.g., calcite, aragonite, vaterite, amorphous calcium carbonate)
in the processes described herein. Such calcium and/or magnesium
carbonates are useful in building materials such as cement,
aggregate, supplementary cementitious materials, and the like.
Alkaline waste and/or by-products of the Solvay process may also be
used in the CO.sub.2-process described herein.
[0035] In one aspect, there is provided a method to produce sodium
carbonate, comprising a) absorbing carbon dioxide in an ammonia
solution to form sodium bicarbonate; and b) subjecting the sodium
bicarbonate to a first electrochemical process to produce sodium
carbonate. In one aspect, there is provided a method to produce
sodium carbonate, comprising a) absorbing carbon dioxide in an
ammonia solution to form sodium bicarbonate; b) subjecting the
sodium bicarbonate to a first electrochemical process to produce
sodium carbonate; and c) regenerating the ammonia solution using
calcium oxide obtained by lime calcinations. In one aspect, there
is provided a method to produce sodium carbonate, comprising a)
absorbing carbon dioxide in an ammonia solution to form sodium
bicarbonate; b) subjecting the sodium bicarbonate to a first
electrochemical process to produce sodium carbonate; and c)
regenerating the ammonia solution using sodium hydroxide obtained
from the first or a second electrochemical process. The first
and/or the second electrochemical processes may be any
electrochemical process described herein.
[0036] In another aspect, there is provided a method to modify a
Solvay process to produce a less carbon dioxide intensive Solvay
process, comprising a) absorbing carbon dioxide in an ammonia
solution to form sodium bicarbonate; and b) subjecting the sodium
bicarbonate to a first electrochemical process to produce sodium
carbonate, thereby resulting in a less carbon dioxide intensive
Solvay process. In one aspect, there is provided a method to modify
a Solvay process to produce a less carbon dioxide intensive Solvay
process, comprising a) absorbing carbon dioxide in an ammonia
solution to form sodium bicarbonate; b) subjecting the sodium
bicarbonate to a first electrochemical process to produce sodium
carbonate; and c) regenerating the ammonia solution using calcium
oxide obtained by lime calcinations, thereby resulting in a less
carbon dioxide intensive Solvay process. In one aspect, there is
provided a method to modify a Solvay process to produce a less
carbon dioxide intensive Solvay process, comprising a) absorbing
carbon dioxide in an ammonia solution to form sodium bicarbonate;
b) subjecting the sodium bicarbonate to a first electrochemical
process to produce sodium carbonate; and c) regenerating the
ammonia solution using sodium hydroxide obtained from the first or
a second electrochemical process, thereby resulting in a less
carbon dioxide intensive Solvay process. The first and/or the
second electrochemical processes may be any electrochemical process
described herein. In some embodiments, the method described above
and herein produces less than 80% carbon dioxide as compared to a
conventional Solvay process. In some embodiments, the method
described above and herein produces less than 90%; or less than
80%; or less than 70%; or less than 60%; or less than 50%; or less
than 40%; or less than 30%; or less than 20%; or less than 10%; or
less than 5%; or less than 5-90%; or less than 5-80%; or less than
5-70%; or less than 5-60%; or less than 5-50%; or less than 5-40%;
or less than 5-30%; or less than 5-20%; or less than 5-10%; or less
than 10-80%; or less than 25-80%; or less than 50-80%; as compared
to a conventional Solvay process.
[0037] For the methods described herein and as above, the methods
do not include bicarbonate calcination, lime calcination, or a
combination thereof.
[0038] FIGS. 2-5 provide some modifications to the Solvay process
of FIG. 1. FIG. 2, for example, illustrates an electrochemical
process in place of Reaction IV ("Bicarb Calcination"). The
electrochemical process is as described herein. Details of such a
modification, as provided in FIG. 2, show that Reaction IV of the
modified process does not produce carbon dioxide, a distinct
advantage over the existing Solvay process. FIG. 3, for example,
illustrates an electrochemical process in place of Reaction II
("Lime Calcination"). The electrochemical process is as described
herein. Details of such a modification, as provided in FIG. 3, show
that Reaction II of the modified process does not produce carbon
dioxide, a distinct advantage over the existing Solvay process.
FIG. 4, for example, illustrates two electrochemical processes, one
for Reaction IV ("Bicarb Calcination") and the other for Reaction
II ("Lime Calcination"). Details of such a modification as provided
in FIG. 4, illustrate that Reactions II and IV of the modified
process do not produce carbon dioxide, a distinct advantage over
the existing Solvay process. FIG. 5, for example, illustrates a
direct capture feature of FIG. 4 as well as a modified Reaction III
("Regeneration"). Some of the advantages of the modified Solvay
process are lower demand for raw materials in Reactions I and III;
less carbon dioxide emissions; and less energy intensive reactions
(reduced or no calcinations). FIG. 5 shares the same soda ash
product as the Solvay process but excises Reactions II and III and
completely modifies Reactions I and II. Additional advantages of
the processes provided in FIGS. 2-5 are provided in the Table I
immediately below.
TABLE-US-00001 TABLE I Replace Bicarb Replace Lime Calcination
Calcination Replace Both CO.sub.2 50% of total CO.sub.2 100% of
total CO.sub.2 100% of total CO.sub.2 Capture Use of 50% reduction
100% reduction 100% reduction CaCO.sub.3 Capex 1) Bicarb 1) Lime 1)
Lime and bicarb calcination calcination calcination eliminated
eliminated eliminated 2) NH.sub.3 absorption 2) NH.sub.3 absorption
and lime calcination reduced by 50% reduced by 50%
[0039] In addition to the advantages provided in the Table I, the
processes of FIGS. 2-5 are less energy intensive and have smaller
carbon footprint than the conventional Solvay process of FIG. 1.
For example, FIG. 6 illustrates carbon dioxide emissions in tonnes
CO.sub.2/tonne of soda ash produced for the processes depicted in
FIGS. 1-5, which correspond to "Solvay w/ Electrochemical process",
"Solvay w/ NaOH Regeneration", "Solvay w/ two Electrochemical
processes", and "Direct Capture". Advantageously, "Solvay w/
Electrochemical process", "Solvay w/ NaOH Regeneration", "Solvay w/
two Electrochemical processes", and "Direct Capture," (respectively
FIGS. 2-5) each emit less carbon dioxide (a measure of energy
efficiency) than the Solvay process provided in FIG. 1. In one
aspect, there is provided a method to produce sodium carbonate,
comprising a) absorbing carbon dioxide in sodium carbonate solution
to form sodium bicarbonate; and b) subjecting the sodium
bicarbonate to an electrochemical process to produce sodium
carbonate. In another aspect, there is provided a less carbon
dioxide intensive method to produce sodium carbonate, comprising a)
absorbing carbon dioxide in sodium carbonate solution to form
sodium bicarbonate; and b) subjecting the sodium bicarbonate to an
electrochemical process to produce sodium carbonate, thereby
resulting in a less carbon dioxide intensive method to produce
sodium carbonate. FIG. 7 illustrates a process using Searles Valley
Minerals (SVM) for producing soda ash. A modification to the
process is illustrated in FIG. 8. In accordance with previously
described process modifications, the process of FIG. 8 replaces the
bicarbonate calcination step with an electrochemical step, which
electrochemical step does not release carbon dioxide. FIG. 9
provides a process for producing soda ash in which there is an
electrochemical step replacing the bicarbonate calcination step
along with recycling of acid. Additional details for the processes
of FIGS. 8-9 are provided in each figure. Some of the advantages of
the processes provided in FIGS. 8-9 are provided in the Table II
below.
TABLE-US-00002 TABLE II SVM Brines w/ ABLE C SVM Brines w/ Acid
Recycle Captured CO.sub.2 100% of total CO.sub.2 N/A Brine usage
Reduces brine usage by N/A 50% Sodium sulfate Available on site
Available on site (can be recycled and/or sold) Sulfuric acid Used
on site (for borate Used on site processing) (for brine titration)
Capex 1) Bicarb calcination 1) Bicarb calcination eliminated
eliminated 2) MEA absorber and regeneration systems eliminated
[0040] In addition to the advantages provided in Table II, the
processes of FIGS. 8-9 are less energy intensive and have smaller
carbon footprints than the Searles Valley Minerals process of FIG.
7. For example, FIG. 10 illustrates carbon dioxide emissions in
tonnes CO.sub.2/tonne of soda ash produced for the processes
depicted in FIGS. 8-9, which correspond to "Alkaline Brines w/
Electrochemical process," "Alkaline Brines w/ Acid Recycle," and
"Direct Capture," respectively, in FIG. 10. Advantageously,
"Alkaline Brines w/ Electrochemical process," "Alkaline Brines w/
Acid Recycle," and "Direct Capture," each emit less carbon dioxide
(a measure of energy efficiency) than the Searles Valley Minerals
process provided in FIG. 7. The direct capture is same as the
direct capture provided in FIG. 5.
[0041] FIG. 11 illustrates a conventional trona ore process where
trona is calcined to form soda ash. FIG. 12 illustrates
modification to the trona-based method for producing soda ash,
modifications including, but not limited to, use of
electrochemistry and/or CO.sub.2 processing (e.g., processing waste
CO.sub.2 produced by calcination of trona). FIG. 12 illustrates one
such method for producing soda ash in a less carbon dioxide
intensive manner. As illustrated, soda ash may be prepared from
trona (1/2Na.sub.2CO.sub.3.NaHCO.sub.3.2H.sub.2O (s)) utilizing
electrochemistry in place of, or in combination with, calcination.
As such, in some embodiments, trona may be mined and/or ground, for
example, to a powder that may be used directly in electrolyte (e.g.
catholyte) for the electrochemical cell or system thereof (e.g.
stack of electrochemical cells), or purified before electrolyte use
to remove impurities. While any of a number of additional salts may
be used in electrolyte for the electrochemical cell(s) or system(s)
thereof as described herein, FIG. 12 illustrates use of either
Na.sub.2SO.sub.4 or NaCl, which provide anolytes comprising
H.sub.2SO.sub.4 or HCl, respectively. Carbonates, as shown in FIG.
12 and described herein, may be electrochemically produced at a low
voltage across the anode and the cathode (e.g., 1.2 V), which
lowers the carbon dioxide footprint of the process provided in FIG.
12 when compared to the basic process provided in FIG. 11.
Following production, such carbonates (e.g., Na.sub.2CO.sub.3) may
be further processed including, but not limited to, liquid-solid
separation, crystallization, recrystallization, and drying. As
such, the system component corresponding to the mining/grinding
step may comprise a mineral processor configured to comminute trona
and other rocks/minerals; the system component corresponding to the
electrochemical step may comprise an electrochemical cell or stack
of electrochemical cells; and the system components corresponding
to crystallization and drying may comprise a liquid-solid
separator, a tank or analogous vessel for
crystallization/recrystallization, and/or a dryer (e.g., spray
dryer).
[0042] Advantageously, "Trona Ore w/ Electrochemical process" emits
less carbon dioxide (a measure of energy efficiency) than the Trona
Ore process provided in FIG. 11. In addition to the process of FIG.
12 being less energy intensive and having smaller carbon footprints
than the Trona Ore process of FIG. 11, the process of FIG. 12 has
additional advantages including, but not limited to, eliminating
CO.sub.2 emissions from calcination.
[0043] In one aspect, there is provide a system comprising a Solvay
system integrated with an electrochemical system, comprising a) a
Solvay system including an absorber configured to absorb carbon
dioxide in an ammonia solution to form sodium bicarbonate; and b) a
first electrochemical system operably connected to the Solvay
system configured to convert the sodium bicarbonate to sodium
carbonate. In another aspect, there is provide a system comprising
a Solvay system integrated with an electrochemical system,
comprising a) a Solvay system including an absorber configured to
absorb carbon dioxide in an ammonia solution to form sodium
bicarbonate; b) a first electrochemical system operably connected
to the Solvay system configured to convert the sodium bicarbonate
to sodium carbonate; and c) a regenerator operably connected to the
Solvay system configured to regenerate the ammonia solution after
absorption of the carbon dioxide in the ammonia solution. In yet
another aspect, there is provide a system comprising a Solvay
system integrated with an electrochemical system, comprising a) a
Solvay system including an absorber configured to absorb carbon
dioxide in an ammonia solution to form sodium bicarbonate; b) a
first electrochemical system operably connected to the Solvay
system configured to convert the sodium bicarbonate to sodium
carbonate; c) a regenerator operably connected to the Solvay system
configured to regenerate the ammonia solution after absorption of
the carbon dioxide in the ammonia solution; and d) a lime calciner
operably connected to the regenerator and configured to produce
calcium oxide for regenerating the ammonia solution. In yet another
aspect, there is provide a system comprising a Solvay system
integrated with an electrochemical system, comprising a) a Solvay
system including an absorber configured to absorb carbon dioxide in
an ammonia solution to form sodium bicarbonate; b) a first
electrochemical system operably connected to the Solvay system
configured to convert the sodium bicarbonate to sodium carbonate;
c) a regenerator operably connected to the Solvay system configured
to regenerate the ammonia solution after absorption of the carbon
dioxide in the ammonia solution; and d) a second electrochemical
system operably connected to the regenerator and configured to
produce sodium hydroxide for regenerating the ammonia solution.
[0044] The Solvay system is any system known in the art to carry
out the Solvay process. The absorber in the Solvay system may be
any absorber configured to absorb carbon dioxide in an ammonia
solution, such as, but not limited to, absorber configured for
bubbling the carbon dioxide gas, stirrers for mixing the gas in the
solution, packed bed for efficient contact between the gas and the
solution, etc. In some embodiments, the solution charged with
CO.sub.2 is made by parging or diffusing the CO.sub.2 gaseous
stream through an ammonia solution to make a CO.sub.2 charged
solution containing sodium bicarbonate. In some embodiments, the
CO.sub.2 gas is bubbled or parged through a solution containing
ammonia in the absorber. In some embodiments, the absorber may
include a bubble chamber where the CO.sub.2 gas is bubbled through
the ammonia solution. In some embodiments, the absorber may include
a spray tower where the ammonia solution is sprayed or circulated
through the CO.sub.2 gas. In some embodiments, the absorber may
include a pack bed to increase the surface area of contact between
the CO.sub.2 gas and the ammonia solution. In some embodiments, a
typical absorber fluid temperature is 32-37.degree. C. For some
embodiments, the absorber for absorbing CO.sub.2 in the solution
may be as described in U.S. application Ser. No. 12/721,549, filed
on Mar. 10, 2010, which is incorporated herein by reference in its
entirety.
[0045] The regenerator in the system described herein may be any
system that can be used for regenerating ammonia (from ammonium
chloride) where the system contains the base (such as calcium oxide
from lime calcinations or sodium hydroxide from electrochemical
process). For example, regenerator can be a tank, or a series of
tanks, or container which may contain conduits or pipes to transfer
and mix the ammonium salt solution and the base to regenerate
ammonia. The ammonia formed may be transferred out of the tank or
container using conduits or pipes.
[0046] The lime calciner in the system described herein may be any
system that can be used for lime calcinations. Such calciners are
well known in the art and are well within the scope of the
invention.
[0047] In some embodiments, the sodium bicarbonate solution from
the Solvay plant is transferred to the electrochemical system for
the generation of soda ash. In some embodiments, the sodium
hydroxide from the electrochemical systems is transferred to the
Solvay plant for the regeneration of the ammonia solution. In some
embodiments, there are provided methods and systems where the
electrochemical systems of the invention are set up on-site of the
Solvay process where sodium bicarbonate from the Solvay process is
administered to the electrochemical system to generate soda ash and
the sodium hydroxide from the electrochemical process is used to
regenerate ammonia solution. In some embodiments, the
electrochemical plant may be fitted close to the Solvay plant
eliminating transportation cost for waste products and allowing
transportation of valuable products only.
[0048] The electrochemical systems are as described herein
below.
Electrochemical Processes and Systems
[0049] The "electrochemical process" or "electrochemical system"
used in the methods and systems described above and herein are
described in this section. Accordingly, the methods and systems
include one or more features of the electrochemical process and
electrochemical cell described herein below. For example, the
electrochemical process described in FIGS. 3 and/or 4 is any
electrochemical process described herein that produces sodium
hydroxide in the catholyte. Similarly, the electrochemical process
described in FIGS. 2, 4, 5, 8, 9, and/or 12 is any electrochemical
process described herein that contacts sodium bicarbonate solution
with the catholyte.
[0050] Described herein are electrochemical systems and methods
where the electrochemical cell electrolyzes a salt solution, such
as, but not limited to, sodium chloride solution to produce sodium
hydroxide in the catholyte and/or sodium carbonate ions and/or
sodium bicarbonate in the catholyte, and an acid in the anolyte.
The systems and methods are not limited to the use of sodium
chloride solution as disclosed in the embodiments described herein
as other salt solutions (e.g., aqueous potassium sulfate,
Na.sub.2SO.sub.4 (aq), etc.) can be used to produce an equivalent
result. In preparing the electrolytes for the system, water from
various sources can be used including seawater, brackish water,
brines or naturally occurring fresh water. In some embodiments,
water may be purified to an acceptable level for use in the
electrochemical system.
[0051] The electrochemical cell comprises an anode in contact with
an anolyte; a cathode in contact with a catholyte; and an ion
exchange membrane disposed between the catholyte and the anolyte.
Accordingly, in one aspect, there is provided a system comprising a
Solvay system integrated with an electrochemical system, comprising
a) a Solvay system comprising an absorber configured to absorb
carbon dioxide in an ammonia solution to form sodium bicarbonate;
and b) a first electrochemical system operably connected to the
Solvay system configured to convert the sodium bicarbonate to
sodium carbonate wherein the electrochemical system comprises an
anode in contact with an anolyte, a cathode in contact with a
catholyte and one or more of ion exchange membrane.
[0052] In some embodiments of the electrochemical systems, with
reference to FIG. 13 herein, in some embodiments the alkaline
solution is produced in the catholyte of an electrochemical system
100 by electrolyzing a salt solution e.g., sodium chloride solution
to produce the alkaline solution, e.g., sodium hydroxide in the
catholyte, and an acid, e.g., hydrochloric acid in the anolyte. The
anode and the cathode may be separated by an ion exchange membrane
(IEM). As used herein, the catholyte is the electrolyte in contact
with the cathode and configured to receive anions e.g., hydroxide
ions from the cathode upon application of a voltage across the
cathode and anode. The catholyte is in a cathode compartment. As
used herein, the anolyte is an electrolyte in contact with the
anode and configured to receive cations e.g., protons from the
anode upon application of the voltage across the cathode and anode.
The anolyte is in an anode compartment.
[0053] In some embodiments of the electrochemical system of FIG.
14, the salt solution e.g., a sodium chloride solution is placed in
a salt solution compartment that is separated from the cathode
compartment by a cation exchange membrane 206. In some embodiments,
as illustrated in FIG. 15, the salt solution is separated from the
anolyte compartment by an anion exchange membrane 210. The cathode
201 and the catholyte 202 form the cathode compartment and the
anode 204 and the anolyte 203 form the anode compartment. Alkali
205 is formed in the catholyte 202 and an acid is formed in the
anolyte 203.
[0054] In one aspect, there is provided a method to produce sodium
carbonate, by a) absorbing carbon dioxide in an ammonia solution to
form sodium bicarbonate; and b) subjecting the sodium bicarbonate
to an electrochemical process to produce sodium carbonate wherein
the electrochemical process comprises contacting anode with an
anolyte, contacting cathode with a catholyte, and producing a base
in the catholyte and an acid in the anolyte. In one aspect, there
is provided a method to produce sodium carbonate, by a) absorbing
carbon dioxide in an ammonia solution to form sodium bicarbonate;
and b) subjecting the sodium bicarbonate to an electrochemical
process to produce sodium carbonate wherein the electrochemical
process comprises contacting anode with an anolyte, contacting
cathode with a catholyte, producing hydrogen gas at the cathode,
transferring hydrogen gas from the cathode to the anode, and
producing a base in the catholyte and an acid in the anolyte. In
some embodiments, the electrochemical process does not comprise
producing a gas such as chlorine gas at the anode. In some
embodiments, the electrochemical process comprises producing
hydroxide at the cathode and hydrochloric acid (using sodium
chloride as anolyte) or sulfuric acid (using sodium sulfate as
anolyte) at the anode.
[0055] In one aspect, there is provided a method to modify a Solvay
process to produce a less carbon dioxide intensive Solvay process,
by a) absorbing carbon dioxide in an ammonia solution to form
sodium bicarbonate; and b) subjecting the sodium bicarbonate to an
electrochemical process to produce sodium carbonate, thereby
resulting in a less carbon dioxide intensive Solvay process wherein
the electrochemical process comprises contacting anode with an
anolyte, contacting cathode with a catholyte, and producing a base
in the catholyte and an acid in the anolyte. In one aspect, there
is provided a method to modify a Solvay process to produce a less
carbon dioxide intensive Solvay process, by a) absorbing carbon
dioxide in an ammonia solution to form sodium bicarbonate; and b)
subjecting the sodium bicarbonate to an electrochemical process to
produce sodium carbonate, thereby resulting in a less carbon
dioxide intensive Solvay process wherein the electrochemical
process comprises contacting anode with an anolyte, contacting
cathode with a catholyte, producing hydrogen gas at the cathode,
transferring hydrogen gas from the cathode to the anode, and
producing a base in the catholyte and an acid in the anolyte. In
some embodiments, the electrochemical process does not comprise
producing a gas such as chlorine gas at the anode. In some
embodiments, the electrochemical process comprises producing
hydroxide at the cathode and hydrochloric acid (using sodium
chloride as anolyte) or sulfuric acid (using sodium sulfate as
anolyte) at the anode.
[0056] In some embodiments, the alkaline solution is produced in
the catholyte by reducing water at the cathode to hydroxide ions
and hydrogen gas in accordance with Eq. 1, by applying a voltage
across the anode and cathode. In some embodiments, concurrent with
the production of hydroxide ions and hydrogen gas at the cathode,
at the anode hydrogen is oxidized to protons in accordance with Eq.
2:
At the cathode: 2H.sub.2O+2e.sup.-.fwdarw.H.sub.2+2OH.sup.- Eq.
1
At the anode: H.sub.2.fwdarw.2H.sup.++2e.sup.- Eq. 2
[0057] In some embodiments, on applying the voltage across the
anode and cathode, hydroxide ions produced at the cathode migrate
into the catholyte to produce the alkaline solution e.g., sodium
hydroxide solution by combining with cations e.g., sodium ions in
the catholyte. Concurrently, in some embodiments, under the applied
voltage across the anode and cathode, the protons formed at the
anode in accordance with Eq. 2 migrate into the anolyte and combine
with anions in the anolyte e.g., chloride ions to produce an acid,
e.g., hydrochloric acid in the anolyte. In some embodiments, the
anions, e.g., chloride ions are migrated into the anolyte through
the anion exchange membrane from the salt solution.
[0058] In some embodiments, hydrogen produced at the cathode is
collected and directed to the anode for oxidation to protons as in
Eq. 2. In some embodiments, since the hydrogen from the cathode is
circulated to the anode therefore the need for externally produced
hydrogen is reduced thereby reducing the overall energy expended in
producing the alkaline solution. This type of the electrochemical
cell and system, where the hydrogen gas is transferred from the
cathode to the anode, has been described as ABLE in the provisional
application to which priority has been claimed.
[0059] In some embodiments, the alkaline solution formed in the
catholyte may be used to regenerate ammonia from the spent ammonia
solution (used for sequestering carbon dioxide gas). In some
embodiments, the alkaline solution may be also used to sequester
carbon dioxide by absorbing the carbon dioxide in the catholyte in
the cathode compartment or by absorbing the carbon dioxide in a gas
absorber operatively connected to the cathode compartment
configured to receive the catholyte and produce a carbonate or
bicarbonate solution.
[0060] In one aspect, there is provided a method to produce sodium
carbonate, by a) absorbing carbon dioxide in an ammonia solution to
form sodium bicarbonate; b) subjecting the sodium bicarbonate to an
electrochemical process to produce sodium carbonate wherein the
electrochemical process comprises contacting anode with an anolyte,
contacting cathode with a catholyte, and producing a base in the
catholyte and an acid in the anolyte; and c) regenerating the
ammonia solution using calcium oxide obtained by lime calcinations
or regenerating the ammonia solution using sodium hydroxide
obtained from the electrochemical process. In one aspect, there is
provided a method to produce sodium carbonate, by a) absorbing
carbon dioxide in an ammonia solution to form sodium bicarbonate;
b) subjecting the sodium bicarbonate to an electrochemical process
to produce sodium carbonate wherein the electrochemical process
comprises contacting anode with an anolyte, contacting cathode with
a catholyte, producing hydrogen gas at the cathode, transferring
hydrogen gas from the cathode to the anode, and producing a base in
the catholyte and an acid in the anolyte; and c) regenerating the
ammonia solution using calcium oxide obtained by lime calcinations
or regenerating the ammonia solution using sodium hydroxide
obtained from the electrochemical process. In some embodiments, the
electrochemical process does not comprise producing a gas such as
chlorine gas at the anode. In some embodiments, the electrochemical
process comprises producing hydroxide at the cathode and
hydrochloric acid (using sodium chloride as anolyte) or sulfuric
acid (using sodium sulfate as anolyte) at the anode.
[0061] In one aspect, there is provided a method to modify a Solvay
process to produce a less carbon dioxide intensive Solvay process,
by a) absorbing carbon dioxide in an ammonia solution to form
sodium bicarbonate; b) subjecting the sodium bicarbonate to an
electrochemical process to produce sodium carbonate, thereby
resulting in a less carbon dioxide intensive Solvay process wherein
the electrochemical process comprises contacting anode with an
anolyte, contacting cathode with a catholyte, and producing a base
in the catholyte and an acid in the anolyte; and c) regenerating
the ammonia solution using calcium oxide obtained by lime
calcinations or regenerating the ammonia solution using sodium
hydroxide obtained from the electrochemical process. In one aspect,
there is provided a method to modify a Solvay process to produce a
less carbon dioxide intensive Solvay process, by a) absorbing
carbon dioxide in an ammonia solution to form sodium bicarbonate;
b) subjecting the sodium bicarbonate to an electrochemical process
to produce sodium carbonate, thereby resulting in a less carbon
dioxide intensive Solvay process wherein the electrochemical
process comprises contacting anode with an anolyte, contacting
cathode with a catholyte, producing hydrogen gas at the cathode,
transferring hydrogen gas from the cathode to the anode, and
producing a base in the catholyte and an acid in the anolyte; and
c) regenerating the ammonia solution using calcium oxide obtained
by lime calcinations or regenerating the ammonia solution using
sodium hydroxide obtained from the electrochemical process. In some
embodiments, the electrochemical process does not comprise
producing a gas such as chlorine gas at the anode. In some
embodiments, the electrochemical process comprises producing
hydroxide at the cathode and hydrochloric acid (using sodium
chloride as anolyte) or sulfuric acid (using sodium sulfate as
anolyte) at the anode.
[0062] In some embodiments of the system of FIG. 16, the alkaline
solution 205 is produced wherein the catholyte 202 is separated
from the anolyte 203 by a cation exchange membranes 206 and an
anion exchange membrane 210 for cations to migrate from salt
solution into the catholyte 202 through the cation exchange
membrane 206 to produce the alkaline solution 205 in the catholyte
202, and for anions to migrate across an anion exchange membrane
210 to produce an acid in the anolyte 203. The ion exchange
membranes comprising a cation exchange membrane separates the
catholyte in the cathode compartment from a third electrolyte. In
various embodiments, the ion exchange membrane comprises an anion
exchange membrane separating the anolyte from the third
electrolyte. In various embodiments, the third electrolyte
comprises sodium ions and chloride ions; the system is configured
to migrate sodium ions from the third electrolyte to catholyte
through the cation exchange membrane, and migrate chloride ions
from the third electrolyte to the anolyte through the anion
exchange membrane.
[0063] In some embodiments, the systems described herein may
include a second cation exchange membrane (not shown in figures)
that is in contact with the anode. In some embodiments, there may
be an additional chamber between the anion exchange membrane and
the anode, such as, a gas diffusion anode (not shown in Figs). The
liquid chamber is in close contact with the anode and the anion
exchange membrane which anion exchange membrane is further in
contact with the center salt compartment.
[0064] As disclosed in U.S. Provisional Patent Application No.
61/081,299, filed 16 Jul. 2008, titled, "Low Energy pH Modulation
for Carbon Sequestration Using Hydrogen Absorptive Metal
Catalysts," herein incorporated by reference in its entirety, in
various embodiments, the anode and the cathode of the present
system may comprise a noble metal, a transition metal, a platinum
group metal, a metal of Groups IVB, VB, VIB, or VIII of the
periodic table of elements, alloys of these metals, or oxides of
these metals. Exemplary materials include palladium, platinum,
iridium, rhodium, ruthenium, titanium, zirconium, chromium, iron,
cobalt, nickel, palladium-silver alloys, and palladium-copper
alloys. In various embodiments, the cathode and/or the anode may be
coated with a reactive coating comprising a metal, a metal alloy,
or an oxide, formed by sputtering, electroplating, vapor
deposition, or any convenient method of producing a layer of
reactive coating on the surface of the cathode and/or anode. In
other embodiments, the cathode and/or the anode may comprise a
coating designed to provide selective penetration and/or release of
certain chemicals or hydroxide ions and/or anti-fouling protection.
Exemplary coatings include non-metallic polymers; in specific
embodiments herein, an anode fabricated from a 20-mesh Ni gauze
material, and a cathode fabricated from a 100-mesh Pt gauze
material was used.
[0065] Reduction of water at the cathode produces hydroxide ions
that migrate into the catholyte. The production of hydroxide ions
in the catholyte surrounding the cathode may increase the pH of the
catholyte. In various embodiments, the solution with the elevated
pH is used in situ, or is drawn off and utilized in a separate
reaction, e.g., to react with sodium bicarbonate as described
herein. Depending on the balance of the rate of hydroxide ion
production versus the rate of carbonate formation in the catholyte,
it is possible for the pH to remain the same or even decrease, as
hydroxide ions are consumed in the reaction.
[0066] Oxidation of hydrogen gas at the anode results in production
of hydrogen ions at the anode that desorb from the structure of the
anode and migrate into the electrolyte surrounding the anode,
resulting in a lowering of the pH of the anolyte. Thus, the pH of
the electrolytes in the system can be adjusted by controlling the
voltage across the cathode and anode and using electrodes comprised
of a material capable of absorbing or desorbing hydrogen ions. In
various embodiments, the process generates hydroxide ions in
solution with less than a 1:1 ratio of CO.sub.2 molecules released
into the environment per hydroxide ion generated. In various
embodiments, the anolyte enriched with hydrogen ions (i.e. an
acid), can be utilized for a variety of applications including
dissolving minerals to produce a solution of divalent cations (e.g.
calcium and/or magnesium ions) for use in generating
carbonate/bicarbonate products.
[0067] In one aspect, there is provided a system comprising a
Solvay system integrated with an electrochemical system, comprising
a) a Solvay system comprising an absorber configured to absorb
carbon dioxide in an ammonia solution to form sodium bicarbonate;
and b) a first electrochemical system operably connected to the
Solvay system configured to convert the sodium bicarbonate to
sodium carbonate wherein the electrochemical system comprises an
anode in contact with an anolyte, a cathode in contact with a
catholyte; one or more of ion exchange membrane; and a hydrogen gas
delivery system operably connected to the cathode compartment and
configured to transfer hydrogen gas from the cathode to the
anode.
[0068] In one aspect, there is provided a system comprising a
Solvay system integrated with an electrochemical system, comprising
a) a Solvay system comprising an absorber configured to absorb
carbon dioxide in an ammonia solution to form sodium bicarbonate;
b) a first electrochemical system operably connected to the Solvay
system configured to convert the sodium bicarbonate to sodium
carbonate wherein the electrochemical system comprises an anode in
contact with an anolyte, a cathode in contact with a catholyte; one
or more of ion exchange membrane; and a hydrogen gas delivery
system operably connected to the cathode compartment and configured
to transfer hydrogen gas from the cathode to the anode; and c) a
regenerator operably connected to the Solvay system configured to
regenerate the ammonia solution after absorption of the carbon
dioxide in the ammonia solution.
[0069] In one aspect, there is provided a system comprising a
Solvay system integrated with an electrochemical system, comprising
a) a Solvay system comprising an absorber configured to absorb
carbon dioxide in an ammonia solution to form sodium bicarbonate;
b) a first electrochemical system operably connected to the Solvay
system configured to convert the sodium bicarbonate to sodium
carbonate wherein the electrochemical system comprises an anode in
contact with an anolyte, a cathode in contact with a catholyte; one
or more of ion exchange membrane; and a hydrogen gas delivery
system operably connected to the cathode compartment and configured
to transfer hydrogen gas from the cathode to the anode; c) a
regenerator operably connected to the Solvay system configured to
regenerate the ammonia solution after absorption of the carbon
dioxide in the ammonia solution; and d) a lime calciner operably
connected to the regenerator and configured to produce calcium
oxide for regenerating the ammonia solution.
[0070] In one aspect, there is provided a system comprising a
Solvay system integrated with an electrochemical system, comprising
a) a Solvay system comprising an absorber configured to absorb
carbon dioxide in an ammonia solution to form sodium bicarbonate;
b) a first electrochemical system operably connected to the Solvay
system configured to convert the sodium bicarbonate to sodium
carbonate wherein the electrochemical system comprises an anode in
contact with an anolyte, a cathode in contact with a catholyte; one
or more of ion exchange membrane; and a hydrogen gas delivery
system operably connected to the cathode compartment and configured
to transfer hydrogen gas from the cathode to the anode; c) a
regenerator operably connected to the Solvay system configured to
regenerate the ammonia solution after absorption of the carbon
dioxide in the ammonia solution; and d) a second electrochemical
system operably connected to the regenerator and configured to
produce sodium hydroxide for regenerating the ammonia solution.
[0071] The first and second electrochemical processes and/or first
and second electrochemical systems, as described herein, may be the
same electrochemical systems and process or may be different
electrochemical processes and systems. For example, in some
embodiments, the first electrochemical process and system may be
the one described in FIG. 13 and the second electrochemical process
and system may be the one described in FIG. 14, or vice versa. For
example, in some embodiments, the first electrochemical process and
system may be the one described in FIG. 14 and the second
electrochemical process and system may be the one described in FIG.
15, or vice versa. For example, in some embodiments, the first
electrochemical process and system may be the one described in FIG.
15 and the second electrochemical process and system may be the one
described in FIG. 16, or vice versa. For example, in some
embodiments, the first electrochemical process and system may be
the same such as the one described in FIG. 13, 14, 15, or 16.
[0072] In some embodiments, the system includes an inlet system
configured to deliver sodium bicarbonate solution (e.g. solution
containing bicarbonate/carbonate ions obtained by absorbing carbon
dioxide gas with ammonia solution) into the catholyte compartment.
In some embodiments, the cathode compartment of the electrochemical
system is operably connected to an absorber that contains ammonia
and is connected to carbon dioxide obtained from Solvay process or
from any other plant, such as steel, cement, or power plant. The
ammonia solution in the absorber after absorbing the carbon dioxide
forms a carbon dioxide charged solution containing bicarbonate
and/or carbonate ions and a spent ammonia (such as ammonium
chloride). This bicarbonate and/or carbonate ion containing
solution may then be transferred to the cathode compartment of the
electrochemical system where the sodium hydroxide generated by the
cathode may convert the remaining bicarbonate to sodium carbonate
resulting in soda ash formation. This type of the electrochemical
cell and system has been described as ABLE-C in the provisional
application to which priority has been claimed. In some
embodiments, the sodium bicarbonate solution from the absorber may
be contacted with the sodium hydroxide from the electrochemical
cell, outside the electrochemical cell, such that the sodium
bicarbonate solution is not administered to the cathode
compartment. As such, similar reaction takes place between the
sodium bicarbonate from the absorber and sodium hydroxide from the
catholyte to form sodium carbonate.
[0073] As illustrated in FIG. 17, a first electrochemical process
400 of FIG. 16 is operably connected to the absorber 500 of the
Solvay system. The ammonia solution in the absorber 500 absorbs
carbon dioxide gas and dissolves it to form sodium bicarbonate
solution (this solution may contain sodium carbonate too). The
sodium bicarbonate solution may be then added to the cathode
compartment of the first electrochemical process where the
hydroxide ions generated at the cathode convert sodium bicarbonate
to sodium carbonate (soda ash). As noted above, in some
embodiments, the sodium bicarbonate solution may be contacted with
the sodium hydroxide from the catholyte outside the electrochemical
cell (not shown in the figure). The spent ammonia in the absorber
(e.g., NH.sub.4Cl) may be then treated with sodium hydroxide
generated at the cathode in the second electrochemical process, to
regenerate ammonia solution. The regenerated ammonia may be
transferred back to the absorber 500. The first and the second
electrochemical systems may be same (as illustrated in FIG. 17) or
may be different, as described herein.
[0074] In various embodiments, the absorber includes a gas
mixer/gas absorber that enhances the absorption of CO.sub.2 in
ammonia. In one embodiment, the gas mixer/gas absorber includes a
series of spray nozzles that produce a flat sheet or curtain of
liquid through which the gas is directed for absorption; in another
embodiment the gas mixer/gas absorber includes spray absorber that
creates a mist into which the gas is directed for absorption; other
commercially available gas/liquid absorber e.g., an absorber
available from Neumann Systems, Colorado, USA may be used. In
operation, the cathode and anode compartments are filled with
electrolytes and a voltage is applied across the cathode and anode.
In various embodiments, the voltage is adjusted to a level to cause
production of hydrogen gas at the cathode without producing a gas,
e.g., chlorine or oxygen, at the anode. In various embodiments, the
system includes a cathode and an anode that facilitate reactions
whereby the catholyte is enriched with hydroxide ions and the
anolyte is enriched with hydrogen ions.
[0075] In various embodiments, a conductive electrolyte solution
can be employed as the electrolyte solution within the reservoir
and in some embodiments the electrolyte solution comprises
seawater, brine, or brackish water.
[0076] As disclosed herein, in various embodiments, hydroxide ions
are produced in the catholyte by applying a relatively low voltage,
e.g., less than 3.0 V, such as less than 2.0 V, or less than 1.0 V
or less than 0.8 V or less than 0.6 V or less than 0.4 V across the
cathode and anode. In various embodiments, hydroxide ions are
produced from water in the catholyte in contact with the cathode,
and carbonate ions are produced in the catholyte by dissolving
sodium bicarbonate solution in the catholyte in the catholyte
compartment. In some embodiments, the electrochemical system
comprises a hydrogen gas delivery system configured to direct
hydrogen gas produced at the cathode to the anode.
[0077] In some embodiments, the catholyte is operatively connected
to the absorber configured to dissolve carbon dioxide in ammonia;
the system is configured to produce a pH differential (.DELTA.pH)
between 0 and 14 or greater between the anolyte and catholyte. For
example, .DELTA.pH may be zero when the catholyte and anolyte are
of equal pH, or .DELTA.pH may be 14 when the catholyte is pH 14 and
the anolyte is pH 0. As such, .DELTA.pH between the anolyte and
catholyte may be greater than 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, or 13; .DELTA.pH between the anolyte and catholyte may be less
than 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1. By the
method, acid produced in the anolyte is utilized to dissolve a
mafic mineral and/or a cellulose material.
[0078] In various embodiments, a gas, e.g., oxygen or chlorine is
not produced at the anode; in various embodiments, hydrogen gas
from an external source is provided to the anode where it is
oxidized to hydrogen ions that migrate into the anolyte to produce
an acid in the anolyte.
[0079] In various embodiments, hydroxide ions produced at the
cathode in the second catholyte compartment migrate into the
catholyte and may cause the pH of the catholyte to adjust, e.g.,
the pH of the catholyte may increase, decrease or remain the same,
depending on the rate of removal of catholyte from the system. In
various embodiments, the pH of the catholyte is adjusted by
producing hydroxide ions from water at the cathode, and allowing
the hydroxide ions to migrate into the catholyte. The pH is also
adjusted by dissolving sodium bicarbonate solution in the catholyte
to produce carbonate ions.
[0080] In some embodiments, the overall cell potential of the
system can be determined through the Gibbs energy change of the
reaction by the formula:
E.sub.cell=-.DELTA.G/nF
[0081] Or, at standard temperature and pressure conditions:
E.degree..sub.cell=-.DELTA.G.degree./nF
where, Ecell is the cell voltage, .DELTA.G is the Gibbs energy of
reaction, n is the number of electrons transferred, and F is the
Faraday constant (96485 J/Vmol). The Ecell of each of these
reactions is pH dependent based on the Nernst equation.
[0082] The overall cell potential can be determined through the
combination of Nernst equations for each half cell reaction:
E=E.degree.-RT ln(Q)/nF
where, E.degree. is the standard reduction potential, R is the
universal gas constant, (8.314 J/mol K) T is the absolute
temperature, n is the number of electrons involved in the half cell
reaction, F is Faraday's constant (96485 J/V mol), and Q is the
reaction quotient such that:
E.sub.total=E.sub.cathode+E.sub.anode
[0083] When hydrogen is oxidized to protons at the anode as
follows:
H.sub.2=2H.sup.++2e.sup.-,
[0084] E.degree. is 0.00 V, n is 2, and Q is the square of the
activity of H+ so that:
E.sub.anode=+0.059pH.sub.a,
[0085] where pH.sub.a is the pH of the anolyte.
[0086] When water is reduced to hydroxide ions and hydrogen gas at
the cathode as follows:
2H.sub.2O+2e.sup.-=H.sub.2+2OH.sup.-,
[0087] E.degree. is -0.83 V, n is 2, and Q is the square of the
activity of OH-- so that:
E.sub.cathode=-0.059pH.sub.c,
where pH.sub.c is the pH of the catholyte.
[0088] Therefore, the E for the cathode and anode reactions varies
with the pH of the anode and catholytes. Thus, if the anode
reaction, which is occurring in an acidic environment, is at a pH
of 0, then the E of the reaction is 0 V for the half cell reaction.
For the cathode reaction, if the generation of bicarbonate ions
occur at a pH of 7, then the theoretical E is 7.times.(-0.059
V)=-0.413 V for the half cell reaction where a negative E means
energy is needed to be input into the half cell or full cell for
the reaction to proceed. Thus, if the anode pH is 0 and the cathode
pH is 7 then the overall cell potential would be 0.413 V,
where:
E.sub.total=-0.059(pH.sub.a-pH.sub.c)=-0.059.DELTA.pH.
[0089] Embodiments in which carbonate ions are produced, if the
anode pH is 0 and the cathode pH is 10, this would represent an E
of 0.59 V.
[0090] Thus, in various embodiments, directing bicarbonate solution
into the catholyte may lower the pH of the catholyte by producing
carbonate ions in the catholyte, and also lower the voltage across
the anode and cathode to produce hydroxide, carbonate and/or
bicarbonate in the catholyte. Thus, operation of the
electrochemical cell with the cathode pH at 7 or greater may
provide a significant energy savings.
[0091] In various embodiments, for different pH values in the
catholyte and the anolyte, hydroxide ions, carbonate ions and/or
bicarbonate ions are produced in the catholyte when the voltage
applied across the anode and cathode was less than 3.0 V, 2.9 V,
2.8 V, 2.7 V, 2.6 V, 2.5 V, 2.4 V, 2.3 V, 2.2 V, 2.1 V, 2.0 V, 1.9
V, 1.8 V, 1.7 V, 1.6 V, 1.5 V, 1.4 V, 1.3 V, 1.2 V, 1.1 V, 1.0 V,
0.9 V, 0.8 V, 0.7 V, 0.6 V, 0.5 V, 0.4 V, 0.3 V, 0.2 V, or 0.1 V.
For selected voltages in the above range, the pH differential
(.DELTA.pH) between the anolyte and the catholyte may be between 0
and 14 or greater. For example, .DELTA.pH may be zero when the
catholyte and anolyte are of equal pH, or .DELTA.pH may be 14 when
the catholyte is pH 14 and the anolyte is pH 0. As such, .DELTA.pH
between the anolyte and catholyte may be greater than 0, 1, 2, 3,
4, 5, 6, 7, 8, 9, 10, 11, 12, or 13; .DELTA.pH between the anolyte
and catholyte may be less than 14, 13, 12, 11, 10, 9, 8, 7, 6, 5,
4, 3, 2, or 1.
[0092] In various embodiments, the system and method are
configurable for batch, semi-batch or continuous flow operation
with or without the option to withdraw portions of the sodium
hydroxide produced in the catholyte, or withdraw all or a portions
of the acid produced in the anolyte, or direct the hydrogen gas
produced at the cathode to the anode where it may be oxidized.
[0093] In various embodiments, hydroxide ions, bicarbonate ions
and/or carbonate ion solutions are produced in the catholyte when
the voltage applied across the anode and cathode is less than 3.0
V, 2.9 V or less, 2.8 V or less, 2.7 V or less, 2.6 V or less, 2.5
V or less, 2.4 V or less, 2.3 V or less, 2.2 V or less, 2.1 V or
less, 2.0 V or less, 1.9 V or less, 1.8 V or less, 1.7 V or less,
1.6 V, or less 1.5 V or less, 1.4 V or less, 1.3 V or less, 1.2 V
or less, 1.1 V or less, 1.0 V or less, 0.9 V or less or less, 0.8 V
or less, 0.7 V or less, 0.6 V or less, 0.5 V or less, 0.4 V or
less, 0.3 V or less, 0.2 V or less, or 0.1 V or less.
[0094] In another embodiment, the voltage across the anode and
cathode can be adjusted such that gas will form at the anode, e.g.,
oxygen or chlorine, while hydroxide ions, carbonate ions and
bicarbonate ions are produced in the catholyte and hydrogen gas is
generated at the cathode. However, in this embodiment, hydrogen gas
is not supplied to the anode. As can be appreciated by one
ordinarily skilled in the art, in this embodiment, the voltage
across the anode and cathode will be higher compared to the
embodiment when a gas does not form at the anode.
[0095] The anion exchange membrane and the cation exchange
membrane, as described herein, can be conventional ion exchange
membranes. In some embodiments, the membranes are capable of
functioning in an acidic and/or basic electrolytic solution and
exhibit high ion selectivity, low ionic resistance, high burst
strength, and high stability in an acidic electrolytic solution in
a temperature range of 0.degree. C. to 100.degree. C. or higher. In
some embodiments a membrane stable in the range of 0.degree. C. to
80.degree. C., or 0.degree. C. to 90.degree. C., but not stable
above these ranges may be used. Suitable membranes include a
Teflon.TM.-based cation exchange membrane available from Asahi
Kasei of Tokyo, Japan. However, low cost hydrocarbon-based cation
exchange membranes can also be utilized, e.g., the
hydrocarbon-based membranes available from, e.g., Membrane
International of Glen Rock, N.J., and USA.
[0096] In some embodiments, the electrolyte including the catholyte
or the cathode electrolyte and/or the anolyte or the anode
electrolyte, or the third electrolyte disposed between AEM and CEM,
in the systems and methods provided herein include, but not limited
to, saltwater or fresh water. The saltwater includes, but is not
limited to, seawater, brine, and/or brackish water. "Saltwater" is
employed in its conventional sense to refer to a number of
different types of aqueous fluids, where the term "saltwater"
includes, but is not limited to, brackish water, sea water and
brine (including, naturally occurring subterranean brines or
anthropogenic subterranean brines and man-made brines, e.g.,
geothermal plant wastewaters, desalination waste waters, etc), as
well as other salines having a salinity that is greater than that
of freshwater. Brine is water saturated or nearly saturated with
salt and has a salinity that is 50 ppt (parts per thousand) or
greater. Brackish water is water that is saltier than fresh water,
but not as salty as seawater, having a salinity ranging from 0.5 to
35 ppt. Seawater is water from a sea or ocean and has a salinity
ranging from 35 to 50 ppt. The saltwater source may be a naturally
occurring source, such as a sea, ocean, lake, swamp, estuary,
lagoon, etc., or a man-made source. In some embodiments, the
systems provided herein include the saltwater from terrestrial
brine. In some embodiments, the depleted saltwater withdrawn from
the electrochemical cells is replenished with salt and
re-circulated back in the electrochemical cell.
[0097] In some embodiments, the electrolyte including the cathode
electrolyte and/or the anode electrolyte and/or the third
electrolyte, such as, saltwater includes water containing more than
1% chloride content, such as, NaCl; or more than 10% NaCl; or more
than 20% NaCl; or more than 30% NaCl; or more than 40% NaCl; or
more than 50% NaCl; or more than 60% NaCl; or more than 70% NaCl;
or more than 80% NaCl; or more than 90% NaCl; or between 1-99%
NaCl; or between 1-95% NaCl; or between 1-90% NaCl; or between
1-80% NaCl; or between 1-70% NaCl; or between 1-60% NaCl; or
between 1-50% NaCl; or between 1-40% NaCl; or between 1-30% NaCl;
or between 1-20% NaCl; or between 1-10% NaCl; or between 10-99%
NaCl; or between 10-95% NaCl; or between 10-90% NaCl; or between
10-80% NaCl; or between 10-70% NaCl; or between 10-60% NaCl; or
between 10-50% NaCl; or between 10-40% NaCl; or between 10-30%
NaCl; or between 10-20% NaCl; or between 20-99% NaCl; or between
20-95% NaCl; or between 20-90% NaCl; or between 20-80% NaCl; or
between 20-70% NaCl; or between 20-60% NaCl; or between 20-50%
NaCl; or between 20-40% NaCl; or between 20-30% NaCl; or between
30-99% NaCl; or between 30-95% NaCl; or between 30-90% NaCl; or
between 30-80% NaCl; or between 30-70% NaCl; or between 30-60%
NaCl; or between 30-50% NaCl; or between 30-40% NaCl; or between
40-99% NaCl; or between 40-95% NaCl; or between 40-90% NaCl; or
between 40-80% NaCl; or between 40-70% NaCl; or between 40-60%
NaCl; or between 40-50% NaCl; or between 50-99% NaCl; or between
50-95% NaCl; or between 50-90% NaCl; or between 50-80% NaCl; or
between 50-70% NaCl; or between 50-60% NaCl; or between 60-99%
NaCl; or between 60-95% NaCl; or between 60-90% NaCl; or between
60-80% NaCl; or between 60-70% NaCl; or between 70-99% NaCl; or
between 70-95% NaCl; or between 70-90% NaCl; or between 70-80%
NaCl; or between 80-99% NaCl; or between 80-95% NaCl; or between
80-90% NaCl; or between 90-99% NaCl; or between 90-95% NaCl. In
some embodiments, the above recited percentages apply to sodium
sulfate as an electrolyte.
[0098] In some embodiments, the cathode compartment may also be
operatively connected to a waste gas treatment system (not
illustrated) where the base solution produced in the catholyte is
utilized, e.g., to sequester carbon dioxide contained in the waste
gas by contacting the waste gas and the catholyte with a solution
of divalent cations to precipitate hydroxides, carbonates and/or
bicarbonates as described in U.S. patent application Ser. No.
12/344,019, filed 24 Dec. 2008, which is incorporated herein by
reference in its entirety.
[0099] In some embodiments, the sodium carbonate (soda ash) may be
treated with divalent cations, such as calcium or magnesium ions,
to precipitate calcium and magnesium carbonates which may be
utilized as building materials, e.g., as cements and aggregates, as
described in U.S. patent application Ser. No. 12/126,776, filed 23
May 2008, which is incorporated herein by reference in its
entirety. In some embodiments, some or all of the carbonates and/or
bicarbonates are allowed to remain in an aqueous medium, e.g., a
slurry or a suspension, and are disposed of in an aqueous medium,
e.g., in the ocean depths.
[0100] In some embodiments, the cathode and anode are also
operatively connected to an off-peak electrical power-supply system
that supplies off-peak voltage to the electrodes. Since the cost of
off-peak power is lower than the cost of power supplied during peak
power-supply times, the system can utilize off-peak power to
produce a base solution in the catholyte at a relatively lower
cost.
[0101] In some embodiments, partially desalinated water is produced
in the third electrolyte as a result of migration of cations and
anions from the third electrolyte to the adjacent anolyte and
catholyte. In various embodiments, the partially desalinated water
is operatively connected to a desalination system (not illustrated)
where it is further desalinated as described in U.S. patent
application Ser. No. 12/163,205, filed 27 Jun. 2008, which is
incorporated herein by reference in its entirety.
[0102] In some embodiments, the system produces an acid, e.g.,
hydrochloric acid in the anolyte. In some embodiments, the anode
compartment is operably connected to a system for dissolving
minerals and waste materials comprising divalent cations to produce
a solution of divalent cations, e.g., Ca.sup.2+ and Mg.sup.2+. In
some embodiments, the divalent cation solution may be utilized to
precipitate divalent carbonates and/or bicarbonates by contacting
the divalent cation solution with sodium carbonate solution. In
various embodiments, the precipitates are used as building
materials e.g., cement and aggregates as described in U.S. patent
application Ser. No. 12/126,776, which is incorporated herein by
reference in its entirety.
[0103] In some embodiments, the system includes a catholyte
withdrawal and replenishing system (not illustrated) capable of
withdrawing all of, or a portion of, the catholyte from the cathode
compartment. In some embodiments, the system also includes a salt
solution supply system (not shown) for providing a salt solution,
e.g., concentrated sodium chloride, as the third electrolyte. In
some embodiments, the system also includes inlet ports (not shown)
for introducing fluids into the cells and outlet ports (not shown)
for removing fluids from the cells.
[0104] In the present system since a gas does not form at the
anode, the system may produce hydroxide ions in the catholyte and
hydrogen gas at the cathode and hydrogen ions at the anode when
less than 2.0 V is applied across the anode and cathode, in
contrast to the higher voltage that is required when a gas is
generated at the anode, e.g., chlorine or oxygen. As will be
appreciated by one ordinarily skilled in the art, by not forming a
gas at the anode and by providing hydrogen gas to the anode for
oxidation at the anode, and by otherwise controlling the resistance
in the system for example by decreasing the electrolyte path
lengths and by selecting ionic membranes with low resistance and
any other method know in the art, hydroxide ions can be produced in
the catholyte with the present lower voltages.
[0105] In various embodiments, depending on the ionic species
desired in the system, alternative reactants can be utilized. Thus,
for example, if a potassium salt such as potassium hydroxide or
potassium carbonate is desired in the cathode electrolyte, then a
potassium salt such as potassium chloride can be utilized as an
electrolyte. Similarly, if sulfuric acid is desired in the anolyte,
then a sulfate such as sodium sulfate can be utilized in
electrolyte.
[0106] In some embodiments, the system and method described herein
are integrated with a carbonate and/or bicarbonate precipitation
system wherein a solution of divalent cations, when added to the
catholyte containing sodium carbonate, causes formation of
precipitates of divalent carbonate and/or bicarbonate compounds,
e.g., calcium carbonate or magnesium carbonate and/or their
bicarbonates. In various embodiments, the precipitated divalent
carbonate and/or bicarbonate compounds may be utilized as building
materials, e.g., cements and aggregates as described for example in
U.S. patent application Ser. No. 12/126,776, filed 23 May 2008,
which is incorporated herein by reference in its entirety.
[0107] In some embodiments, the system and method described herein
are integrated with a mineral and/or material dissolution and
recovery system (not illustrated) wherein the acidic anolyte
solution is utilized to dissolve calcium and/or magnesium-rich
minerals e.g., serpentine or olivine, or waste materials, e.g., fly
ash, red mud and the like, to form divalent cation solutions that
may be utilized, e.g., to precipitate carbonates and/or
bicarbonates as described herein.
[0108] In some embodiments, the system and method described herein
are integrated with an aqueous desalination system (not
illustrated) wherein the partially desalinated water of the third
electrolyte of the system is used as feed-water for the
desalination system, as described in U.S. patent application Ser.
No. 12/163,205, filed 27 Jun. 2008, which is incorporated herein by
reference in its entirety.
[0109] In some embodiments, the system and method described herein
are integrated with a carbonate and/or bicarbonate solution
disposal system (not illustrated) wherein, rather than producing
precipitates by contacting a solution of divalent cations with
sodium carbonate to form precipitates, the system produces a slurry
or suspension comprising carbonates and/or bicarbonates. In various
embodiments, the slurry or suspension is disposed of in a location
where it is held stable for an extended periods of time, e.g., the
slurry/suspension is disposed in an ocean at a depth where the
temperature and pressure are sufficient to keep the slurry stable
indefinitely, as described in U.S. patent application Ser. No.
12/344,019, filed 24 Dec. 2008, which is herein incorporated by
reference in its entirety.
[0110] In some embodiments, the systems provided herein may include
a processor to process the compositions containing bicarbonate
and/or carbonate products. An illustrative example of the processor
is described in FIG. 18. For example, in some embodiments, the
processor includes a reactor configured to react soda ash obtained
from the electrochemical system (such as FIGS. 13-17 described
herein) with divalent cations from a source of divalent cations to
produce compositions containing carbonate/bicarbonate products. In
some embodiments, the processor may further comprise a settling
tank configured for settling compositions. The processor may
further comprise a treatment system configured to concentrate
compositions comprising carbonates, bicarbonates, or carbonates and
bicarbonates and produce a supernatant; however, in some
embodiments the compositions may be used without further treatment.
For example, systems may be configured to directly use compositions
from the reactor (optionally with minimal post-processing) in the
manufacture of building materials. In another non-limiting example,
systems may be configured to directly inject compositions from the
processor (optionally with minimal post-processing) into a
subterranean site as described in U.S. Provisional Patent
Application No. 61/232,401, filed 7 Aug. 2009, which is
incorporated herein by reference in its entirety. The source of
divalent cations may be from any of a variety of sources of
divalent cations, including, but not limited to, seawater, brines,
and freshwater with added minerals. In some embodiments, the source
of divalent cations comprises divalent cations of alkaline earth
metals (e.g., Ca.sup.2+, Mg.sup.2+).
[0111] The treatment system may comprise a liquid-solid separator
or some other dewatering system configured to treat
processor-produced compositions to produce supernatant and
concentrated compositions (e.g., concentrated with respect to
carbonates and/or bicarbonates). The treatment system may further
comprise a filtration system, wherein the filtration system
comprises at least one filtration unit configured for filtration of
supernatant from the dewatering system, filtration of the
composition from the processor, or a combination thereof. For
example, in some embodiments, the filtration system comprises one
or more filtration units selected from a microfiltration unit, an
ultrafiltration unit, a nanofiltration unit, and a reverse osmosis
unit. In some embodiments, the processing system comprises a
nanofiltration unit configured to increase the concentration of
divalent cations in the retentate and reduce the concentration of
divalent cations in the filtrate. In such embodiments,
nanofiltration unit retentate may be recirculated to a processor of
the system for producing compositions described herein.
[0112] In some embodiments, the calcium carbonate composition
formed by the processes described herein comprises vaterite,
aragonite, amorphous calcium carbonate, calcite, or combination
thereof. In some embodiments, such calcium carbonate (optionally
containing magnesium carbonate) forms a cementitious material. The
cementitous composition has elements or markers that originate from
the carbon from the source of carbon used in the process. The
composition after setting, and hardening has a compressive strength
of at least 14 MPa; or at least 16 MPa; or at least 18 MPa; or at
least 20 MPa; or at least 25 MPa; or at least 30 MPa; or at least
35 MPa; or at least 40 MPa; or at least 45 MPa; or at least 50 MPa;
or at least 55 MPa; or at least 60 MPa; or at least 65 MPa; or at
least 70 MPa; or at least 75 MPa; or at least 80 MPa; or at least
85 MPa; or at least 90 MPa; or at least 95 MPa; or at least 100
MPa; or from 14-100 MPa; or from 14-80 MPa; or from 14-75 MPa; or
from 14-70 MPa; or from 14-65 MPa; or from 14-60 MPa; or from 14-55
MPa; or from 14-50 MPa; or from 14-45 MPa; or from 14-40 MPa; or
from 14-35 MPa; or from 14-30 MPa; or from 14-25 MPa; or from 14-20
MPa; or from 14-18 MPa; or from 14-16 MPa; or from 17-35 MPa; or
from 17-30 MPa; or from 17-25 MPa; or from 17-20 MPa; or from 17-18
MPa; or from 20-100 MPa; or from 20-90 MPa; or from 20-80 MPa; or
from 20-75 MPa; or from 20-70 MPa; or from 20-65 MPa; or from 20-60
MPa; or from 20-55 MPa; or from 20-50 MPa; or from 20-45 MPa; or
from 20-40 MPa; or from 20-35 MPa; or from 20-30 MPa; or from 20-25
MPa; or from 30-100 MPa; or from 30-90 MPa; or from 30-80 MPa; or
from 30-75 MPa; or from 30-70 MPa; or from 30-65 MPa; or from 30-60
MPa; or from 30-55 MPa; or from 30-50 MPa; or from 30-45 MPa; or
from 30-40 MPa; or from 30-35 MPa; or from 40-100 MPa; or from
40-90 MPa; or from 40-80 MPa; or from 40-75 MPa; or from 40-70 MPa;
or from 40-65 MPa; or from 40-60 MPa; or from 40-55 MPa; or from
40-50 MPa; or from 40-45 MPa; or from 50-100 MPa; or from 50-90
MPa; or from 50-80 MPa; or from 50-75 MPa; or from 50-70 MPa; or
from 50-65 MPa; or from 50-60 MPa; or from 50-55 MPa; or from
60-100 MPa; or from 60-90 MPa; or from 60-80 MPa; or from 60-75
MPa; or from 60-70 MPa; or from 60-65 MPa; or from 70-100 MPa; or
from 70-90 MPa; or from 70-80 MPa; or from 70-75 MPa; or from
80-100 MPa; or from 80-90 MPa; or from 80-85 MPa; or from 90-100
MPa; or from 90-95 MPa; or 14 MPa; or 16 MPa; or 18 MPa; or 20 MPa;
or 25 MPa; or 30 MPa; or 35 MPa; or 40 MPa; or 45 MPa. For example,
in some embodiments of the foregoing aspects and the foregoing
embodiments, the composition after setting, and hardening has a
compressive strength of 14 MPa to 40 MPa; or 17 MPa to 40 MPa; or
20 MPa to 40 MPa; or 30 MPa to 40 MPa; or 35 MPa to 40 MPa. In some
embodiments, the compressive strengths described herein are the
compressive strengths after 1 day, or 3 days, or 7 days, or 28
days.
[0113] In some embodiments, electrochemical cells (e.g., a stack of
electrochemical cells) may be operably connected to the above
described processing system configured to precipitate a
precipitation material comprising bicarbonates and/or carbonates
(or a processed form thereof). Such carbonates and/or bicarbonates
comprise calcium and/or magnesium. In some embodiments, the
electrochemical cell or the stack of electrochemical cells may be
operably connected to a system for further processing of the
anolyte, which may comprise hydrochloric acid (if NaCl(aq) is used)
or sulfuric acid (if Na.sub.2SO.sub.4 (aq) is used). For example,
in some embodiments, the electrochemical cell or the stack of
electrochemical cells may be operably connected to a
mineral-processing system comprising a mineral processor configured
to dissolve minerals (e.g., mafic minerals such as olivine,
serpentine, etc.) with the anolyte (e.g., hydrochloric acid and
sodium chloride, sulfuric acid and sodium carbonate, etc.) and
produce a solution comprising calcium and/or magnesium ions. In
some embodiments, the anolyte may be used for other purposes in
addition to, or instead of, mineral dissolution, including use as a
reactant in production of cellulosic biofuels, use in the
production of polyvinyl chloride (PVC), and the like. Systems
appropriate for such uses may be operably connected to the stack of
electrochemical cells, or the anolyte may be transported to an
appropriate site for use.
EXAMPLE
Example 1
[0114] A solvay process is performed by absorbing carbon dioxide
into ammonia solution in sodium chloride. The carbon dioxide is
obtained from flue gas emitted by a power plant. The carbon dioxide
gas is bubbled into the ammonia+sodium chloride solution. The
carbon dioxide gas dissolves in the solution to form sodium
bicarbonate and ammonium chloride is generated. Sodium bicarbonate
is separated from the ammonium solution and is subjected to the
electrochemical process for carbonate formation.
Example 2
[0115] This study demonstrates the savings in the voltage when an
electrochemical cell was run with sodium hydroxide as catholyte vs.
sodium bicarbonate as catholyte. A voltage sweep was performed in
an electrochemical cell that was containing a 3-cell system (e.g.,
electrochemical cell of FIG. 16) with an anode and an anode
electrolyte in an anode compartment, a cathode and a catholyte in a
cathode compartment, and the anode compartment and the cathode
compartment separated by an anion exchange membrane and a cation
exchange membrane.
[0116] In one set of experiment, a voltage sweep was performed in
the electrochemical cell where the anode was in contact with 0.5 wt
% hydrochloric acid solution, the cathode was in contact with 10 wt
% sodium hydroxide solution, and sodium chloride solution was in
the middle chamber between ion exchange membranes. In another set
of experiment, a voltage sweep was performed in the electrochemical
cell that was containing anode in contact with 0.5 wt %
hydrochloric acid solution, cathode in contact with 1 mol/L sodium
bicarbonate solution (at pH 10), and sodium chloride solution was
in the middle chamber between ion exchange membranes. The 1 mol/L
sodium bicarbonate solution was formed by bubbling carbon dioxide
in 1 mol sodium hydroxide solution that resulted in the formation
of 1 mol/L sodium bicarbonate solution.
[0117] FIG. 19 illustrates that significant savings in the voltage
were observed by introducing sodium bicarbonate into the catholyte
(.about.250 mV) as compared to sodium hydroxide. The sodium
hydroxide generated at the cathode converted bicarbonate to
carbonate. The conversion of bicarbonate to carbonate depended on
flow rates, current density and length of time.
[0118] While preferred embodiments have been shown and described
herein, it will be obvious to those skilled in the art that such
embodiments are provided by way of example only. Numerous
variations, changes, and substitutions will now occur to those
skilled in the art. It should be understood that various
alternatives to the embodiments described herein may be employed
without departing from spirit of this specification. It is intended
that the following claims define the scope of the invention and
that methods and structures within the scope of these claims and
their equivalents be covered thereby.
* * * * *