U.S. patent application number 13/630223 was filed with the patent office on 2013-05-30 for method for production of succinic acid and sulfuric acid by paired electrosynthesis.
This patent application is currently assigned to Zhejiang University of Technology. The applicant listed for this patent is Zhejiang University of Technology. Invention is credited to Yunfang Gao.
Application Number | 20130134047 13/630223 |
Document ID | / |
Family ID | 42585821 |
Filed Date | 2013-05-30 |
United States Patent
Application |
20130134047 |
Kind Code |
A1 |
Gao; Yunfang |
May 30, 2013 |
METHOD FOR PRODUCTION OF SUCCINIC ACID AND SULFURIC ACID BY PAIRED
ELECTROSYNTHESIS
Abstract
A method for the production of succinic acid and sulfuric acid
by paired electrolytic synthesis is disclosed in the present
invention. The method is described as following: in cathodic
compartment of an electrochemical cell separated with cation
exchange membrane, maleic acid or maleic anhydride is used as raw
material, sulfuric acid as the cathodic reactant and the supporting
electrolyte of the reaction system, succinic acid is thus
synthesized by the electro-reduction reaction at cathode. In anodic
compartment, the aqueous sulfuric acid solution containing iodide
ion is used as electrolyte, iodide ion is anodized to form I.sub.2
and I.sub.3.sup.-. SO.sub.2 gas is fed into the circulated anolyte,
reacting with I.sub.2 and I.sub.3.sup.- to form sulfuric acid and
regenerate iodide ion. Simultaneously the evaporated hydroiodic
acid and distilled water are returned to the anolyte circulation
system. The cell voltage and the cost of production are reduced
significantly.
Inventors: |
Gao; Yunfang; (Hangzhou,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zhejiang University of Technology; |
Hangzhou |
|
CN |
|
|
Assignee: |
Zhejiang University of
Technology
Hangzhou
CN
|
Family ID: |
42585821 |
Appl. No.: |
13/630223 |
Filed: |
September 28, 2012 |
Current U.S.
Class: |
205/349 |
Current CPC
Class: |
C25B 3/04 20130101 |
Class at
Publication: |
205/349 |
International
Class: |
C25B 3/04 20060101
C25B003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2010 |
CN |
201010137720.4 |
Claims
1. A method for the production of succinic acid and sulfuric acid
by paired electrolytic synthesis comprising: inside cathodic
compartment of an electrochemical cell separated with cation
exchange membrane, maleic acid or maleic anhydride is used as raw
material, sulfuric acid as the cathodic reactant and the supporting
electrolyte of the reaction system, succinic acid is thus
synthesized by the electro-reduction reaction at cathode. When the
extent of electrolysis reaction reaches a certain degree, catholyte
is taken out and post-processed to obtain succinic acid. In anodic
compartment, the aqueous sulfuric acid solution containing iodide
ion is used as electrolyte, iodide ion is anodized to form I.sub.2
and I.sub.3.sup.-. SO.sub.2 gas is fed into the circulated anolyte,
reacting with I.sub.2 and I.sub.3.sup.- through redox reaction to
form sulfuric acid and regenerate iodide ion in anolyte. When the
concentration of sulfuric acid in the anolyte reaches a certain
degree, the anolyte is taken out to be concentrated to obtain
sulfuric acid of high concentration. Simultaneously, the hydroiodic
acid and the distilled water evaporated from the anolyte are
returned to the anolyte circulation system.
2. The method of claim 1, wherein inside said electrochemical cell,
graphite or titanium-supported RuO.sub.2--TiO.sub.2 electrode is
used as anode, lead or lead alloys as cathode. The distance between
the cathode and the anode is 5.about.50 mm.
3. The method of claim 1, wherein during the process of
electrolysis reaction, the concentration of reactants in said
catholyte is controlled as following: sulfuric acid 0.5.about.3
mol/L, maleic acid 0.5.about.3 mol/L; the concentration of
reactants in said anolyte as following: sulfuric acid 0.5.about.7
mol/L, iodide ion 0.5.about.4 mol/L. The molar ratio of the total
amount of I.sub.2 and I.sub.3.sup.- generated through the anodic
reaction to SO.sub.2 fed from outside is controlled at
1:(1.about.1.5).
4. The method of claim 3, wherein the current density of cathode
and anode is controlled at 300.about.1200 A/m.sup.2 and
300.about.1500 A/m.sup.2, respectively.
5. The method of claim 1, wherein the post-processing of said
catholyte after electrolysis reaction comprising: said catholyte
thus obtained is cooled, precipitated, filtered, rinsed, dried to
obtain succinic acid; the mother liquor from filtration is returned
to said cathodic compartment after supplementing maleic acid or
maleic anhydride.
6. The method of claim 1, wherein the temperature of said
electrolysis reaction is controlled at the range of 20-70.degree.
C.
7. The method of claim 1, wherein the temperature of said
electrolysis reaction is controlled at the range of 30-50.degree.
C.
8. The method of claim 1, wherein said paired electrolytic
synthesis is operated in two modes: batch-type and continuous-type.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International Patent
Application No. PCT/CN2011/072346, with an international filing
date of Mar. 31, 2011, designating the United States, now pending,
and further claims priority benefits to Chinese Patent Application
No. 201010137720.4, filed Apr. 1, 2010. The contents of all of the
aforementioned applications, including any intervening amendments
thereto, are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a method for production of succinic
acid and sulfuric acid by paired electrosynthesis.
[0004] 2. Description of the Related Art
[0005] Succinic acid is an important chemical raw material which is
colorless or white crystalline, odorless and sour taste. It is
widely used in the fields of pharmaceuticals, pesticides, fine
chemicals and alkyd resin. In recent years, succinic acid has been
widely used in the fields of biodegradable plastics, polybutylene
succinate (PBS), and organic coatings etc.
[0006] There are three main methods to synthesize succinic acid:
chemical synthesis, biological conversion and electrolysis
method.
[0007] At present, most of succinic acid for industrial use is
produced by chemical synthesis method which includes oxidation and
catalytic hydrogenation. Although those technologies have been
developed and applied practically, there are still many problems
existing such as the uncontrollable side reactions, low yield, low
purity of the product, high requirement in operation and usage of
expensive catalyst, etc. Furthermore, there is serious
environmental pollution in its production process.
[0008] In recent years, the method of producing succinic acid with
bacterial or microbial fermentation has become a research focus
worldwide because it uses starch, glucose, milk and other waste as
raw material. However, a large amount of research still needs to be
investigated and completed, such as low extraction efficiency, low
production and conversion rate, high production cost, generation of
a large amount of wastewater, etc. It is estimated that more than
10 tons of wastewater is generated in producing 1 ton of succinic
acid. Therefore, it is hard to meet the requirement of industrial
production. At present, the biological conversion technology is
still limited to the laboratory scale and needs much more time to
be commercialized.
[0009] Succinic acid can be also produced by electrolytic reduction
method in which maleic acid or maleic anhydride is used as the
reactant. The production of succinic acid with electrolytic
technology had been industrialized in 1930s. After nearly 80 years
of development of the technology, the electrolytic synthesis
technology becomes more and more mature, leading to accomplish
higher conversion ratio, yield, purity and current efficiency in
producing succinic acid. In the meantime, zero discharge of
wastewater is reached by recycling mother liquor. Therefore, the
electrolytic technology has been considered as a green chemical
synthesis technology.
[0010] According to the literature, the electrolytic technology of
succinic acid production can be fulfilled in two ways named as
membrane technique and membrane-free technique. At present, the
membrane-free technique has been adopted widely, as indicated in
the patents 200710047530.1 (Chinese patent application),
200610148269. x(Chinese patent application), etc. The
electrooxidation reaction with oxygen evolution has almost always
been adopted as the anodic reaction in most present industrial
production of succinic acid in which PbO.sub.2 anode is chosen as
anode material. However, the disadvantage in this method is that
the cell voltage is high, the life of PbO.sub.2 anode is short and
the initial investment of the anode is high. Other than oxygen
evolution reaction, it was also reported that the electro-oxidation
reaction of glyoxal to glyoxylic acid had been adopted as the
anodic reaction (Fine Chemicals, Chinese journal, 1997, 14(5),
56.about.57), but the yields of glyoxylic acid and succinic acid
are both relatively low.
[0011] In the present invention, a new technology for electrolytic
synthesis of succinic acid and sulfuric acid is disclosed. The
principle of the technology is based on the paired electrolytic
synthesis, in which succinic acid is formed by the
electro-reduction of maleic acid (or maleic anhydride) and the
redox couple of I.sup.-/I.sub.2 is used as anodic mediator to
produce sulfuric acid. Sulfuric acid is obtained in the anolyte
circulation system through the redox reaction of I.sub.2 (or
I.sub.3.sup.-) with sulfur dioxide gas fed into the anolyte from
outside. Iodine (or I.sub.3.sup.-) is generated through the
electrooxidation reaction of iodide. Therefore, the present
invention is a novel technology in producing succinic acid and
sulphuric acid at the same time with paired electrolytic
technology.
SUMMARY OF THE INVENTION
[0012] The present invention discloses a technical solution for
producing succinic acid and sulfuric acid with paired electrolytic
synthesis. By selecting suitable anodic reaction, the cell voltage
and the cost of production are reduced significantly, the current
efficiency is high and the electrolyte is recycled. Meantime, the
problems of short lifetime of anode and environmental pollution are
solved.
[0013] In order to solve the above technique problems, a technical
solution adopted in the present invention is as following.
[0014] A technical solution in producing succinic acid and sulfuric
acid with paired electrolytic synthesis, said solution is: using
maleic acid or maleic anhydride as raw material of the cathodic
reaction, sulfuric acid as the cathodic reactant and the supporting
electrolyte of the reaction system; the anolyte and cathloyte
compartments in the electrochemical cell are separated each other
with cation-exchange membrane; the reaction occurred on the cathode
is described as the following equations:
##STR00001##
[0015] As the electrolytic reaction in the cathodic compartment
proceeds to a certain degree, succinic acid is generated by
post-processing catholyte. The technicians in this field can
monitor the extent of the reaction according to the electricity
consumed theoretically.
[0016] In the anodic compartment, sulfuric acid solution containing
iodide ion is used as anolyte, iodide ion is anodized to form
I.sub.2 and I.sub.3.sup.-, and SO.sub.2 gas is fed into the anolyte
continuously which is circulated within the system. Sulfuric acid
is produced and iodide ion is regenerated through the redox
reaction of I.sub.2 and I.sub.3.sup.-, with sulfur dioxide. When
the concentration of sulfuric acid in the anolyte reaches a certain
degree, the anolyte is post-processed to obtain higher
concentration sulfuric acid. Simultaneously, evaporated hydroiodic
acid and the distilled water are isolated and returned to the
anolyte circulation system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] A detailed description of accompanying drawings will be
provided below.
[0018] FIG. 1 is a schematic diagram of an experimental apparatus
applied in the current invention embodiment, where: 1-anode,
2-cathode, 3-anolyte tank, 4-catholyte tank, 5-cation exchange
membrane, 6-flow controlling valve, 7-electrolyte circulation pump,
8-SO.sub.2 inlet.
[0019] FIG. 2 is the process flow diagram of the present
invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0020] Detailed description will be given below in conjunction with
accompanying drawings.
[0021] In anodic compartment, the aqueous sulfuric acid solution
containing iodide ion is used as the electrolyte and the sulfur
dioxide gas is fed into the anolyte circulation system, the
following electrooxidation reaction takes place.
2I.sup.-.fwdarw.I.sub.2+2e (or
3I.sup.-.fwdarw.I.sub.3.sup.-.fwdarw.2e) (1)
[0022] In the above anodic reaction, the iodide ion is regenerated
through the following chemical redox reaction of I.sub.2 and
I.sub.3.sup.- with SO.sub.2 or H.sub.2SO.sub.3. In the meantime,
sulfuric acid is produced as well. The reactions can be expressed
as the followings.
I.sub.2+SO.sub.2+2H.sub.2O.dbd.H.sub.2SO.sub.4+2HI (2)
H.sub.2SO.sub.3+I.sub.2+H.sub.2O=4H.sup.++2I.sup.-+SO.sub.4.sup.2-
(3)
I.sub.3.sup.-+SO.sub.2+2H.sub.2O=4H.sup.++3I.sup.-+SO.sub.4.sup.2-
(4)
[0023] In the anodic compartment, sulphur dioxide gas is fed into
the anolyte where sulfurous acid is formed through the reaction of
SO.sub.2 and water.
[0024] A cation exchange membrane is used to separate the
electrochemical cell adopted in the present invention. In said
electrochemical cell, the anode materials resistant to the
corrosion in strongly acidic solution containing iodide are used as
the anode, as preferred, graphite and DSA electrode
(RuO.sub.2--TiO.sub.2/Ti anode). The cathode materials with high
overpotential of hydrogen evolution are employed as cathode, as
preferred, lead and lead alloys. The distance between the cathode
and anode is kept as short as possible, as preferred, 5.about.50
mm.
[0025] In the reaction process of the present invention, the
preferred conditions are: the concentration of reactants in the
cathodic compartment is controlled as following: sulfuric acid
0.5.about.3 mol/L, maleic acid 0.5.about.3 mol/L; the concentration
of reactants in the anolyte is controlled as following: sulfuric
acid 0.5.about.7 mol/L, iodide ion 0.5.about.4 mol/L. The molar
ratio of the total of I.sub.2 and I.sub.3.sup.-, generated through
the anodic reaction to SO.sub.2 fed from the outside is controlled
at 1:(1.about.1.5). The preferred current density of the cathode
and anode is 300.about.1200 A/m.sup.2 and 300.about.1500 A/m.sup.2,
respectively.
[0026] The electrolysis process of the present invention is
operated using batch-type and continuous-type modes. Said
continuous-type mode is carried out as following: adding reactants
needed continuously, taking part of electrolyte out of the system
for post-processing after the electrolysis reaction reaches a
certain degree, returning the mother liquor from the
post-processing to the electrolyte system after supplementing raw
material; said batch-type mode is operated as follows: adding
catholyte in one time or several times, feeding SO.sub.2 to the
anolyte continuously, replacing the electrolyte with fresh
electrolyte when the electrolysis reaction reaches a certain
degree, post-processing the electrolyte containing reaction
products, supplementing raw material in the post-processed
electrolyte and using it as fresh electrolyte.
[0027] The post-processing method of the catholyte in the present
invention is as following: cooling the catholyte, filtering the
cooled catholyte to get succinic acid crystal, rinsing the succinic
acid crystal and drying it to obtain succinic acid product. The
mother liquor generated in filtering is returned to the catholyte
circulation system after supplementing maleic acid or maleic
anhydride. As a result, the yield of succinic acid is increased,
the consumption of raw material is reduced, and the cost of
production is decreased. In the meantime, green production is
achieved.
[0028] The post-processing method of the anolyte in the present
invention is as following: post-processing the anolyte to get
concentrated sulfuric acid after the concentration of sulfuric acid
reaches a certain degree, in the meantime, returning the evaporated
hydroiodic acid and steam to the anolyte circulation system.
[0029] In addition, the temperature of the electrolyte has a large
influence on the electrolysis reaction because the solubility of
succinic acid increases with the temperature of the electrolyte.
When the temperature of the electrolyte is too low, large amount of
succinic acid will precipitate to form crystal during the process
of electrolysis, leading to the increase of the cell voltage and
affecting the electrolysis reaction. However, high temperature of
the electrolyte will damage the equipment of electrolysis and
shorten the life of membrane. The reaction temperature is
maintained at 20.about.70.degree. C., as preferred,
30.about.50.degree. C.
[0030] The experimental equipment used in the present invention
includes: a cation membrane-separated electrochemical cell, an
anolyte tank and an catholyte tank. Said electrochemical cell is
separated into anodic compartment installed with anode and cathodic
compartment installed with cathode. Said electrochemical cell could
be assembled and connected in mono-polar or bi-polar way. The inlet
port of said anodic compartment is set at the bottom and connected
to the outlet port of the anolyte tank through pump and flow
controlling valve. The outlet of said anodic compartment is set at
the top and connected to the inlet port of the anolyte tank,
constituting an anolyte circulation system. The inlet port of said
cathodic compartment is set at the bottom and connected to the
outlet port of the catholyte tank at the bottom through pump and
flow controlling valve. The outlet of cathodic compartment is set
at the top and connected to the inlet port of catholyte tank,
constituting a catholyte circulation system. In the present
invention, there are two ways for sulfur dioxide gas to be fed into
the anolyte circulation system: one is to feed sulfur dioxide gas
into the anodic compartment directly where an oxidation-reduction
reaction takes place, the other is to feed sulfur dioxide gas into
the anolyte tank where the oxidation-reduction reaction takes
place.
[0031] Compared with the related art, the beneficial results of the
present invention include: (1) reducing the energy consumption of
succinic acid electrolytic synthesis significantly by adopting
appropriate paired anodic and cathodic reactions, (2) decreasing
the initial investment and production cost by using inexpensive
anode material, overcoming the problem of short lifetime of anode,
(3) providing a new wet technology to produce sulfuric acid at low
temperatures, (4) increasing current efficiency, recycling
electrolyte and achieving green production. The technology of the
present invention is suitable for industrial scale production.
Example 1
[0032] A mono-polar membrane-separated electrochemical cell is
used. Graphite and lead are used as anode and cathode,
respectively. The apparent area of both the anode and the cathode
is 50 cm.sup.2. The distance between the anode and the cathode is
40 mm. A homogeneous cation exchange membrane made of
polyvinylidene fluoride (F101 type) is used in the cell.
[0033] The electrolytic technological parameters are chosen as
follows: the initial concentration of KI and sulfuric acid in the
anodic compartment is 1 mol/L, the initial concentration of
sulfuric acid and maleic anhydride in the cathodic compartment is 1
mol/L, the temperature of the electrolyte is controlled at the
range of 30.about.35.degree. C. The electrolyte in the anolyte and
cathodic compartments is circulated through pump set on their
respective tank. The total amount of anolyte and catholyte is 3
liters, respectively. SO.sub.2 gas is fed into the anodic
compartment. Slight excess of SO.sub.2 gas is kept to ensure that
the solution in the anodic compartment remains green yellow (not
brown). The current density of the electrolysis reaction is 1000
A/m.sup.2, and the average cell voltage is 2.38 V.
[0034] After 10 hours at constant current density, the electrolysis
reaction is stopped, and the catholyte is taken out for
post-processing. After post-treatment which includes cooling,
crystallization, filtration, rinsing with icy deionized water and
drying, 68.4 g succinic acid is obtained finally. The cathodic
current efficiency is calculated to be 95.1%.
Example 2
[0035] A mono-polar membrane-separated electrochemical cell is
used. Graphite and lead are used as anode and cathode,
respectively. The apparent area of both the anode and the cathode
is 50 cm.sup.2. The distance between the anode and the cathode is
40 mm. A homogeneous cation exchange membrane made of
polyvinylidene fluoride (F101 type) is used in the cell.
[0036] The electrolytic technological parameters are chosen as
follows: the anolyte in the anodic compartment is the anolyte after
electrolysis reaction in Example 1, the catholyte in the cathodic
compartment is the mother liquor of the catholyte in Example 1. The
initial concentration of maleic acid in the catholyte is adjusted
to be 1 mol/L by supplementing maleic anhydride. The temperature of
the electrolyte is controlled at the range of 50.about.55.degree.
C. Other technological parameters are the same as those in Example
1. The average cell voltage is 2.26 V.
[0037] After 5 hours at constant current density, the electrolysis
reaction is stopped, and the catholyte is taken out for
post-processing. After post-treatment which includes cooling,
crystallization, filtration, rinsing with icy deionized water and
drying, 51.1 g succinic acid is obtained finally. The cathodic
current efficiency is calculated to be 94.2%.
Example 3
[0038] A mono-polar membrane-separated electrochemical cell is
used. DSA and lead are used as anode and cathode, respectively. The
apparent area of both the anode and the cathode is 50 cm.sup.2. The
distance between the anode and the cathode is 20 mm. A homogeneous
cation exchange membrane made of Nafion 117 is used in the
cell.
[0039] The electrolytic technological parameters are chosen as
follows: the anolyte in the anodic compartment is the anolyte after
electrolysis reaction in Example 2, the catholyte in the cathodic
compartment is the mother liquor of the catholyte in Example 2. The
initial concentration of maleic acid in the catholyte is adjusted
to be 1.2 mol/L by supplementing maleic anhydride. The temperature
of the electrolyte is controlled at the range of
30.about.35.degree. C. SO.sub.2 gas is fed into the anolyte tank.
Other technological parameters are the same as those in Example 1.
The average cell voltage is 1.38 V.
[0040] After 10 hours at constant current density, the electrolysis
reaction is stopped, and the catholyte is taken out for
post-processing. After post-treatment which includes cooling,
crystallization, filtration, rinsing with icy deionized water and
drying, 52.2 g succinic acid is obtained finally. The cathodic
current efficiency is calculated to be 94.9%.
Example 4
[0041] A mono-polar membrane-separated electrochemical cell is
used. Graphite and lead are used as anode and cathode,
respectively. The apparent area of both the anode and the cathode
is 100 cm.sup.2. The distance between the anode and the cathode is
15 mm. A homogeneous cation exchange membrane made of Nafion 117 is
used in the cell.
[0042] The electrolytic technological parameters are chosen as
follows: the anolyte in the anodic compartment is the anolyte after
electrolysis reaction in Example 3, the catholyte in the cathodic
compartment is the mother liquor of the catholyte in Example 3. The
initial concentration of maleic acid in the catholyte is adjusted
to be 0.8 mol/L by supplementing maleic acid. The temperature of
the electrolyte is controlled at the range of 40.about.45.degree.
C. SO.sub.2 gas is fed into the anodic compartment. The current
density of the anode and the cathode is controlled at 750
A/m.sup.2. Other technological parameters are the same as those in
Example 1. The average cell voltage is 1.59V.
[0043] After 2 hours at constant current density, the electrolysis
reaction is stopped, and the catholyte is taken out for
post-processing. After post-treatment which includes cooling,
crystallization, filtration, rinsing with icy deionized water and
drying, 31.2 g succinic acid is obtained finally. The cathodic
current efficiency is calculated to be 94.5%.
Example 5
[0044] A mono-polar membrane-separated electrochemical cell is
used. Graphite and lead are used as anode and cathode,
respectively. The apparent area of both the anode and the cathode
is 100 cm.sup.2. The distance between the anode and the cathode is
15 mm. A homogeneous cation exchange membrane made of Nafion 117 is
used in the cell.
[0045] The electrolytic technological parameters are chosen as
follows: the anolyte in the anodic compartment is the anolyte after
electrolysis reaction in Example 4, the catholyte in the cathodic
compartment is the mother liquor of catholyte in Example 4. The
initial concentration of maleic acid in the catholyte is adjusted
to be 0.8 mol/L by supplementing maleic acid. The temperature of
the electrolyte is controlled at the range of 50.about.55.degree.
C. SO.sub.2 gas is fed into the anodic compartment. The current
density of the anode and the cathode is controlled at 1200
A/m.sup.2. Other technological parameters are the same as those in
Example 1. The average cell voltage is 1.64V.
[0046] After 2 hours at constant current density, the electrolysis
reaction is stopped, and the catholyte is taken out for
post-processing. After post-treatment which includes cooling,
crystallization, filtration, rinsing with icy deionized water and
drying, 49.7 g succinic acid is obtained finally. The cathodic
current efficiency is calculated to be 94.1%.
[0047] After the above five examples (from Example 1 to Example 5)
are finished, the anolyte is taken out for analysis. The results
show the concentration of sulfate in the anolyte is 1.83 mol/L, the
total average anodic current efficiency is calculated to be 96.56%.
The anolyte is taken out to be concentrated. After the volume of
the anolyte is reduced to 1 L by evaporating, the concentration of
sulfuric acid is found to be 5.49 mol/L. The evaporated substances
are collected and returned to the anolyte circulation system after
cooling.
* * * * *