U.S. patent application number 13/940953 was filed with the patent office on 2014-06-26 for method for producing biodiesel.
The applicant listed for this patent is NATIONAL PINGTUNG UNIVERSITY OF SCIENCE AND TECHNOLOGY. Invention is credited to Ho-Hsien Chen, Tzou-Chi Huang, Chao-Yi Wei.
Application Number | 20140173974 13/940953 |
Document ID | / |
Family ID | 50973062 |
Filed Date | 2014-06-26 |
United States Patent
Application |
20140173974 |
Kind Code |
A1 |
Chen; Ho-Hsien ; et
al. |
June 26, 2014 |
METHOD FOR PRODUCING BIODIESEL
Abstract
A method for producing biodiesel includes feeding methanol into
a tank and heating methanol to a temperature above a critical
temperature of methanol to obtain a supercritical methanol. A
reactive matrix is fed into the tank. The reactive matrix includes
acetic acid and a material oil. A molar ratio of acetic acid to the
material oil is in a range from 1:1 to 5:1. A molar ratio of
methanol to the material oil is in a range from 20:1 to 90:1. A
supercritical carbon dioxide is fed into the tank. A total pressure
of the supercritical methanol and the supercritical carbon dioxide
is higher than 10 MPa. The supercritical methanol, the material
oil, acetic acid, and the supercritical carbon dioxide react with
each other in the tank at 240-500.degree. C. and 8.1-50 MPa for
0.1-1.5 hours to obtain biodiesel.
Inventors: |
Chen; Ho-Hsien; (Pingtung
County, TW) ; Huang; Tzou-Chi; (Pingtung County,
TW) ; Wei; Chao-Yi; (Pingtung County, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NATIONAL PINGTUNG UNIVERSITY OF SCIENCE AND TECHNOLOGY |
Pingtung County |
|
TW |
|
|
Family ID: |
50973062 |
Appl. No.: |
13/940953 |
Filed: |
July 12, 2013 |
Current U.S.
Class: |
44/388 |
Current CPC
Class: |
C10L 1/026 20130101;
C07C 67/03 20130101; Y02P 20/141 20151101; Y02P 20/544 20151101;
C07C 67/08 20130101; Y02E 50/13 20130101; Y02P 20/54 20151101; C11C
3/003 20130101; Y02E 50/10 20130101; Y02P 20/142 20151101; C07C
68/04 20130101; C07C 67/08 20130101; C07C 69/24 20130101; C07C
67/08 20130101; C07C 69/14 20130101; C07C 68/04 20130101; C07C
69/96 20130101; C07C 67/03 20130101; C07C 69/52 20130101 |
Class at
Publication: |
44/388 |
International
Class: |
C10L 1/02 20060101
C10L001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2012 |
TW |
101149388 |
May 30, 2013 |
TW |
102119187 |
Claims
1. A method for producing biodiesel comprising: feeding methanol
into a tank and heating methanol to a temperature above a critical
temperature of methanol to obtain a supercritical methanol; feeding
a reactive matrix into the tank, with the reactive matrix including
acetic acid and a material oil, with a molar ratio of acetic acid
to the material oil being in a range from 1:1 to 5:1, with a molar
ratio of methanol to the material oil being in a range from 20:1 to
90:1; and adding a supercritical carbon dioxide into the tank, with
a total pressure of the supercritical methanol and the
supercritical carbon dioxide being higher than 10 MPa, wherein the
supercritical methanol, the material oil, acetic acid, and the
supercritical carbon dioxide react with each other in the tank at
240-500.degree. C. and 8.1-50 MPa for 0.1-1.5 hours to obtain
biodiesel.
2. The method as claimed in claim 1, wherein the molar ratio of
methanol to the material oil is 60:1.
3. The method as claimed in claim 1, wherein the molar ratio of
acetic acid to the material oil is 3:1.
4. The method as claimed in claim 2, wherein a volumetric ratio of
methanol to the material oil is 2.5:1.
5. The method as claimed in claim 3, wherein a volumetric ratio of
acetic acid to the material oil is 1:6.4.
6. The method as claimed in claim 1, wherein methanol is heated to
a temperature in a range of 240-500.degree. C. to obtain the
supercritical methanol.
7. The method as claimed in claim 1, wherein the material oil is
selected from the group consisting of plant oils, animal oils,
waste cooking oils, and oils or fats containing glycerol ester and
fatty acids and combinations thereof.
8. The method as claimed in claim 7, wherein the material oil is
soybean oil.
9. The method as claimed in claim 1, wherein supercritical
methanol, the material oil, acetic acid, and the supercritical
carbon dioxide react with each other in the tank at 280.degree. C.
and 20 MPa.
10. The method as claimed in claim 1, wherein supercritical
methanol, the material oil, acetic acid, and the supercritical
carbon dioxide react with each other in the tank for 90 minutes.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for producing
biodiesel and, more particularly, to a method for producing
biodiesel by using a supercritical fluid.
[0003] 2. Description of the Related Art
[0004] Biodiesel (fatty acid methyl ester or FAME) is one of
bioenergy resources for replacing fossil fuels to slow down the
global warming effect.
[0005] Conventional methods for producing biodiesel, including a
conventional base catalytic method using a catalyst (an alkaline
substance, such as sodium hydroxide or potassium hydroxide) and a
conventional supercritical alcohol production methodology, proceed
with a transesterification reaction and separate free fatty acids
from animal fats, plant oils, or waste oils for conversion into
useful biodiesel. However, in the conventional base catalytic
method, the alkaline substance is liable to reside in biodiesel in
addition to generation of a large amount of glycerol as a
by-product that is difficult to remove (see the reaction formula
shown in FIG. 1), failing to provide a satisfactory conversion
rate. In the conventional supercritical alcohol production
methodology, biodiesel still has a large amount of glycerol as the
by-product although catalysts are not used.
[0006] In another conventional method for producing biodiesel
disclosed in Taiwan Patent Publication No. 201105789, a large
amount of acetic acid is used to hydrolyze fatty acids in Jatrapha
curcas L. seed oil, and methanol is then used to proceed with
supercritical methanolysis, obtaining biodiesel. The conventional
method includes a two-stage reaction (including a subcritical
hydrolysis reaction and a supercritical methanolysis reaction) to
complete production of biodiesel. The subcritical hydrolysis
reaction requires a lot of acetic acid, and free fatty acid is then
hydrolyzed and separated from acetic acid. The procedures are
complicated while the disadvantage of a large quantity of glycerol
as the by-product also exists. Thus, the conventional method can
not be used to effectively produce biodiesel.
[0007] In another conventional method proposed by Zul Ilham and
Shiro Saka, biodiesel is produced from supercritical dimethyl
carbonate using methyl acetate as a catalyst ("A new process for
catalyst-free production of biodiesel using supercritical methyl
acetate", 2009; "Dimethyl carbonate as potential reactant in
non-catalytic biodiesel production by supercritical method", 2009).
Although the conventional method can effectively reduce the amount
of glycerol as the by-product, formation of dimethyl carbonate by
chemical engineering is costly and requires complicated operation,
causing a bottleneck to production of biodiesel.
[0008] Furthermore, in the conventional methods for producing
biodiesel mentioned above, plant oils preferable in maintaining the
quality of biodiesel necessitate additional extraction process,
increasing the costs and time for producing biodiesel.
[0009] Thus, a need exists for a novel method for producing
biodiesel that mitigates and/or obviates the above
disadvantages.
SUMMARY OF THE INVENTION
[0010] The primary objective of the present invention is to provide
a method for producing biodiesel by using inexpensive and
easy-to-obtain materials.
[0011] Another objective of the present invention is to provide a
method for producing biodiesel while generating a less amount of
glycerol, avoiding an increase in the costs.
[0012] A further objective of the present invention is to provide a
method for producing biodiesel by directly using various cooking
oils or waste cooking oils as material oils to simplify the
process.
[0013] The present invention fulfills the above objectives by
providing a method for producing biodiesel including feeding
methanol into a tank and heating methanol to a temperature above a
critical temperature of methanol to obtain a supercritical
methanol. A reactive matrix is fed into the tank. The reactive
matrix includes acetic acid and a material oil. A molar ratio of
acetic acid to the material oil is in a range from 1:1 to 5:1. A
molar ratio of methanol to the material oil is in a range from 20:1
to 90:1. A supercritical carbon dioxide is fed into the tank. A
total pressure of the supercritical methanol and the supercritical
carbon dioxide is higher than 10 MPa. The supercritical methanol,
the material oil, acetic acid, and the supercritical carbon dioxide
react with each other in the tank at 240-500.degree. C. and 8.1-50
MPa for 0.1-1.5 hours to obtain biodiesel.
[0014] Preferably, the molar ratio of methanol to the material oil
is 60:1.
[0015] Preferably, the molar ratio of acetic acid to the material
oil is 3:1.
[0016] Preferably, a volumetric ratio of methanol to the material
oil is 2.5:1.
[0017] Preferably, a volumetric ratio of acetic acid to the
material oil is 1:6.4.
[0018] Preferably, methanol is heated to a temperature in a range
of 240-500.degree. C. to obtain the supercritical methanol.
[0019] Preferably, the material oil is selected from the group
consisting of plant oils, animal oils, waste cooking oils, and oils
or fats containing glycerol ester and fatty acids and combinations
thereof.
[0020] Preferably, the material oil is soybean oil.
[0021] Preferably, supercritical methanol, the material oil, acetic
acid, and the supercritical carbon dioxide react with each other in
the tank at 280.degree. C. and 20 MPa.
[0022] Preferably, supercritical methanol, the material oil, acetic
acid, and the supercritical carbon dioxide react with each other in
the tank for 90 minutes.
[0023] By using the method for producing biodiesel according to the
present invention, the amount of glycerol as the by-product can be
effectively reduced while saving the costs and operation time as
well as recycling and reusing waste cooking oils.
[0024] The present invention will become clearer in light of the
following detailed description of illustrative embodiments of this
invention described in connection with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The illustrative embodiments may best be described by
reference to the accompanying drawings where:
[0026] FIG. 1 shows a reaction formula of producing glycerol of a
by-product in the conventional method.
[0027] FIG. 2 shows a reaction formula in a method for producing
biodiesel according to the present invention.
[0028] FIG. 3 shows another reaction formula in the method for
producing biodiesel according to the present invention.
[0029] FIG. 4 shows the other reaction formula in the method for
producing biodiesel according to the present invention.
[0030] FIG. 5 shows a schematic diagram of a device for producing
biodiesel according to the present invention.
[0031] All figures are drawn for ease of explanation of the basic
teachings of the present invention only; the extensions of the
figures with respect to number, position, relationship, and
dimensions of the parts to form the preferred embodiments will be
explained or will be within the skill of the art after the
following teachings of the present invention have been read and
understood. Further, the exact dimensions and dimensional
proportions to conform to specific force, weight, strength, and
similar requirements will likewise be within the skill of the art
after the following teachings of the present invention have been
read and understood.
DETAILED DESCRIPTION OF THE INVENTION
[0032] A method for producing biodiesel according to the present
invention includes feeding methanol into a tank; heating methanol
to a temperature above a critical temperature of methanol to obtain
a supercritical methanol; feeding a reactive matrix containing
acetic acid and a material oil with a molar ratio of acetic acid to
the material oil in a range from 1:1 to 5:1 into the tank, wherein
a molar ratio of methanol to the material oil is in a range from
20:1 to 90:1; and adding a supercritical carbon dioxide into the
tank, with a total pressure of the supercritical methanol and the
supercritical carbon dioxide being higher than 10 MPa. The
supercritical methanol, the material oil, acetic acid, and the
supercritical carbon dioxide react with each other in the tank at
240-500.degree. C. and 8.1-50 MPa for 0.1-1.5 hours to obtain
biodiesel.
[0033] Specifically, the method for producing biodiesel according
to the present invention uses a suitable amount of acetic acid as a
reactive matrix for transesterification reaction. Acetic acid can
catalyze hydrolysis of fatty acids and proceed with a reaction
shown in FIGS. 2-4. Therefore acetic acid completely reacts for
subsequent reaction with methanol in the method for producing
biodiesel without the need of separation steps. Preferably, the
molar ratio of acetic acid to the material oil is 3:1, and a
volumetric ratio of acetic acid to the material oil is 1:6.4.
Preferably, the molar ratio of methanol to the material oil is
60:1, and a volumetric ratio of methanol to the material oil is
2.5:1. Thus, acetic acid completely reacts and reduces the yield of
glycerol as a by-product.
[0034] With reference to FIGS. 1-3, acetic acid assists in
separation of fatty acids from the material oil, produces free
fatty acids and the free fatty acids react with methanol to obtain
glycerol as the by-product (see FIG. 1). Nevertheless, the acetic
acid used in the method according to the present invention has a
suitable amount to react with glycerol as the by-product to form
glycerol ester, reducing the amount of glycerol, as shown in FIG.
4. Furthermore, acetic acid reacts with methanol to generate methyl
acetate and dimethyl carbonate to increase the conversion rate of
biodiesel and to reduce the amount of glycerol as the by-product,
as shown in FIG. 2.
[0035] In an example, methanol is fed by a pump into the tank.
Preferably, methanol is 99% methanol, and acetic acid is 99%
glacial acetic acid to completely react with methanol in a manner
mentioned in the above paragraph without the need of additional
processes for separation of unreacted acetic acid. The reaction
time was about 0.1-1.5 hours, depending upon the size of a reaction
system (for example, the tank mentioned above). The larger the
reaction system is, the longer the reaction time is. As an example,
the reaction time is about 15 minutes for a reaction system of 6 ml
or about 1.5 hours for a reaction system of 150 ml.
[0036] Furthermore, methanol is heated to a temperature above its
critical temperature, preferably in range of 240-500.degree. C.,
more preferably 280.degree. C., to obtain supercritical methanol
for assisting in the reaction (the reaction shown in FIG. 1) and to
increase the reaction rate.
[0037] The material oil is selected from the group consisting of
plant oils, animal fats, waste cooking oils, and oils or fats
containing glycerol ester and fatty acids and combinations thereof.
In this example, the material oil is waste cooking oil to recycle
the waste cooking oil and to reduce the amount of waste cooking
oil.
[0038] Finally, supercritical carbon dioxide is added to increase
the solubility of supercritical methanol and the reactive matrix
and to stabilize the pressure in the tank. The total pressure of
the supercritical carbon dioxide and supercritical methanol is
higher than 10 MPa, preferably 20-50 MPa, and more preferably 20
MPa.
[0039] FIG. 5 shows an embodiment of a device for producing
biodiesel according to the present invention, including two
high-pressure pumps 1 and 2, a high-pressure tank 3, and a heater
4. Methanol and the supercritical carbon dioxide are fed by the
high-pressure pumps 1 and 2 into the high-pressure tank 3 and
heated by the heater 4. Each high-pressure pump 1, 2 has an inlet
valve b 11, 12 to control a feeding rate of the supercritical
carbon dioxide or methanol. The high-pressure tank 3 is connected
to a temperature controlling unit "a" and a pressure controlling
unit "b" for controlling temperature and pressure in the
high-pressure tank 3. Furthermore, the high-pressure tank 3 is
connected to an exhaust valve "v" for discharging product.
[0040] In an example, methanol of 75.93 ml is fed by the
high-pressure pump 1 into the high-pressure tank 3 (having a volume
of 150 ml) and heated by the heater 4 to 280.degree. C. Methanol
transforms into its supercritical state and is mixed with the
reactive matrix that is fed by the high-pressure pump 1 into the
high-pressure tank 3 at a highest flow rate of 10 ml/min. The
reactive matrix consists of 30 ml of soybean oil and 4.68 ml of 99%
glacial acetic acid (wherein a molar ratio of methanol to soybean
oil is 60:1, and a molar ratio of acetic acid to soybean oil was
3:1). Then, the supercritical carbon dioxide is fed by the
high-pressure pump 2 into the high-pressure tank 3 at a highest
flow rate of 200 ml/min, such that the total pressure of the
supercritical carbon dioxide and the supercritical methanol is 20
MPa. Reaction is carried out in the high-pressure tank 3 at
280.degree. C. and 20 MPa for 90 minutes, generating biodiesel that
is discharged via the exhaust valve "v". Table 1 shows a result of
the example according to the present invention. Referred to the
reaction formula and a formula shown below, the conversion rate of
biodiesel is 97.83% and an amount of glycerol as the by-product in
the method according to the present invention is reduced by 30.2%
in comparison with the conventional base catalytic method or the
conventional supercritical alcohol production methodology. The
formula used is listed below:
(molecular weight of glycerol.times.1)/(molecular weight of
methanol.times.3+molecular weight of
triglyceride.times.1).times.100%=yield of glycerol
TABLE-US-00001 TABLE 1 glycerol as conversion rate by-product (%)
of FAME (%) Conventional 10.26 96% method Method of the 3.09 97.83%
present invention
[0041] In view of the foregoing, the method for producing biodiesel
according to the present invention effectively reduces the amount
of glycerol as the by-product. The method for producing biodiesel
uses a suitable amount of acetic acid and methanol as the reactive
matrix such that biodiesel can be produced in a single stage
without additional steps of separating unreacted reactive matrix,
saving the costs and operation time.
[0042] Furthermore, the method for producing biodiesel according to
the present invention can be used in various cooking oils, even
waste cooking oils. Thus, waste cooking oils can be recycled and
reused while assuring the quality of biodiesel.
[0043] Thus since the invention disclosed herein may be embodied in
other specific forms without departing from the spirit or general
characteristics thereof, some of which forms have been indicated,
the embodiments described herein are to be considered in all
respects illustrative and not restrictive. The scope of the
invention is to be indicated by the appended claims, rather than by
the foregoing description, and all changes which come within the
meaning and range of equivalency of the claims are intended to be
embraced therein.
* * * * *