Technical Field
[0001] The present invention relates to a method of preparing allyl alcohol from glycerol
and allyl alcohol prepared thereby. More particularly, the present invention relates to a
method of preparing allyl alcohol from glycerol using formic acid in a specific
equivalent amount at a specific reaction temperature, and to allyl alcohol prepared
thereby.
Background Art
[0002] Allyl alcohol has been mainly utilized to prepare polymer resins, medical
products and fine chemical products, and is mostly derived from propylene obtained by
petrochemical processes.
[0003] To overcome problems of fossil fuel exhaustion, techniques for synthesizing
biodiesel from biomass, for example, vegetable or animal oil, have been
commercialized, and the demand therefor is increasing.
[0004] Typically, biodiesel is produced via transesterification of vegetable oil and
alcohol. In this procedure, glycerol is produced as a byproduct. This glycerol may be
employed in a large amount, and is a renewable material that may be easily stored or
transported, and is thus regarded as a promising material for preparation of allyl alcohol.
[0005] Preparation of allyl alcohol from glycerol is based on a two-step reaction
mechanism, including a first step for dehydration of glycerol into acrolein and a second
step for hydrogenation of acrolein into allyl alcohol.
[0006] In this regard, the first step is disclosed in U.S. Patent Nos. 7,396,962, 7,655,818,
7,683,220, 7,718,829, and 7,951,978, and the second step is disclosed in U.S. Patent
Nos. 4,072,727, and 5,892,066. However, these reaction processes are complicated and
difficult to carry out, and result in high separation and purification costs, and thus
become unsuitable for use in industrial mass production. Moreover, such processes,
which are carried out in the presence of a catalyst, are problematic because the catalyst
2
has to be periodically replaced and high costs may result.
[0007] Direct preparation of allyl alcohol from glycerol not through acrolein is
described in ChemSusChem 2012, Vol 5, pp 1401-1404, but employs a catalyst,
undesirably generating byproducts such as 1,3-dihydroxyacetone. Also, as disclosed in
Angew. Chem. Int. Ed. 2012, Vol 51, pp 8082-8086, the preparation process requires the
use of an expensive rhenium catalyst, and is thus inappropriate for use in industrial mass
production.
[0008] Although preparation of allyl alcohol from glycerol without the use of a catalyst
was proposed (Kamm et al, Organic Syntheses, Coll. Vol. 1, 1941), the allyl alcohol
yield was very low.
[0009] Therefore, with the goal of preparing allyl alcohol from glycerol, a byproduct of
a biodiesel synthesis process, there is an urgent need for a method of preparing allyl
alcohol at high yield via liquid reaction at relatively low reaction temperature without
the use of a catalyst.
Disclosure
Technical Problem
[0010] The present invention has been made keeping in mind the above problems
encountered in the related art, and an object of the present invention is to provide a
method of preparing allyl alcohol at high yield from glycerol via liquid reaction at
relatively low reaction temperature without the use of a catalyst.
Technical Solution
[0011] In order to accomplish the above object, the present invention provides a method
of preparing allyl alcohol, comprising mixing glycerol with formic acid in an amount of
0.8 ~ 2 equivalents relative to 1 equivalent of glycerol, and reacting them at a reaction
temperature of 220 ~ 260°C.
[0012] In addition, the present invention provides allyl alcohol prepared by the method
as described above.
Advantageous Effects
[0013] According to the present invention, a method of preparing allyl alcohol enables
3
the allyl alcohol to be produced at a high yield of 80% or more via liquid reaction at
relatively low reaction temperature without the use of a catalyst.
Best Mode
[0014] Hereinafter, a detailed description will be given of a method of preparing allyl
alcohol according to the present invention.
[0015] The present invention addresses a method of preparing allyl alcohol, comprising
mixing glycerol with formic acid in an amount of 0.8 ~ 2 equivalents relative to 1
equivalent of glycerol, and increasing a reaction temperature to 220 ~ 260°C from room
temperature at a heating rate of 2.0 ~ 7.0 °C/min so that glycerol and formic acid are
reacted.
[0016] Glycerol is a compound represented by HOCH2(CHOH)CH2OH, and is also
referred to as trihydroxypropane or glycerin. Although the purity of glycerol does not
limit the scope of the present invention, it is 80 wt% or higher, preferably 90 wt% or
higher, and more preferably 95 wt% or higher, in order to reduce production of reaction
byproducts.
[0017] In the present invention, the inventors utilized the glycerol which can be obtained
as a byproduct from a biodiesel synthesis process via transesterification of vegetable oil
and alcohol.
[0018] The method of preparing allyl alcohol from glycerol according to the present
invention is a liquid phase reaction, which is carried out at a relatively low temperature,
namely, 300°C or less, compared to a gas phase reaction. Hence, this reaction is
favorable in terms of energy costs, compared to conventional preparation of allyl alcohol
via gas reaction.
[0019] Direct preparation of allyl alcohol via reaction between glycerol and formic acid
according to the present invention is conducted as in Scheme 1 below.
[Scheme 1]
[0020] In Scheme 1, carboxylic acid reacting with glycerol is exemplified by formic
acid. As such, formic acid is advantageous because carbon dioxide, which is produced
as a reaction byproduct of allyl alcohol preparation, may thus be easily removed. The
4
other carboxylic acids may generate byproducts, and undesirably require additional
separation and purification processes.
[0021] When the method of preparing allyl alcohol according to the present invention is
performed in an oxygen-containing gas atmosphere, oxidative decomposition of glycerol
or carbonization may occur, which may result in lowering the product yield. Hence, this
reaction is preferably carried out in an inert gas atmosphere.
[0022] The inert gas may be any one selected from the group consisting of nitrogen,
argon and helium, and the gas phase reaction products may include at least one selected
from the group consisting of carbon dioxide, water vapor, allyl formate, allyl alcohol,
and unreacted formic acid. The liquid phase reaction products may include at least one
selected from the group consisting of allyl alcohol, allyl formate, unreacted formic acid,
and water.
[0023] As shown in Scheme 1, since glycerol and formic acid react at 1:1, the equivalent
amount herein refers to a molar amount.
[0024] In the method of preparing allyl alcohol according to the present invention, the
reaction temperature is increased to 220 ~ 260°C, preferably 230 ~ 250°C, and more
preferably 230 ~ 240°C, thus enabling the production of allyl alcohol at high yield from
glycerol. If the reaction temperature is lower than 220°C, the reaction intermediate,
glyceryl formate, does not proceed to the next step. In contrast, if the reaction
temperature is higher than 260°C, the reaction byproduct, allyl formate, may be
produced in a significant amount.
[0025] In the method of preparing allyl alcohol according to the present invention, the
heating rate may be set to 2.0 ~ 7.0 °C/min so that the reaction temperature for reacting
glycerol and formic acid reaches 220 ~ 260°C from room temperature. If the heating
rate is less than 2.0 °C/min, the production of allyl formate may increase. In contrast, if
the heating rate is higher than 7.0 °C/min, the rate of vaporization of formic acid may
drastically increase, undesirably resulting in the remarkable decrease of the glycerol
conversion.
[0026] In the method of preparing allyl alcohol according to the present invention,
formic acid is used in an amount of 0.8 ~ 2 equivalents, and preferably 1.2 ~ 1.7
equivalents, relative to 1 equivalent of glycerol. If the amount of formic acid is less than
the lower limit, the allyl alcohol selectivity may increase whereas the glycerol
5
conversion may decrease, undesirably resulting in low allyl alcohol yield. In contrast, if
the amount of formic acid exceeds the upper limit, the glycerol conversion may increase
but the allyl alcohol selectivity may decrease, undesirably lowering the allyl alcohol
yield.
[0027] In the method of preparing allyl alcohol according to the present invention, the
allyl alcohol is prepared at a yield of 60% or more, and preferably 75% or more.
[0028] Since the allyl alcohol yield prepared by the method as above is high, it may be
industrially useful.
[0029] Also, since a catalyst as disclosed in ChemSusChem 2012, Vol 5, pp 1401-1404
is not used in the present invention, byproducts such as 1,3-dihydroxyacetone are not
generated. Furthermore, the reaction of the present invention proceeds without using an
expensive rhenium catalyst as disclosed in Angew. Chem. Int. Ed. 2012, Vol 51, pp
8082-8086, and is thus economically suitable for industrial mass production.
[0030] The method of the present invention may be performed using any one or more
selected from among a batch reactor, a continuous stirred tank reactor (CSTR), and a
plug flow reactor (PFR), which are typically used by those skilled in the art, and the kind
and combination thereof are not limited herein.
Mode for Invention
[0031] The following examples of the present invention are disclosed for illustrative
purposes, but those skilled in the art will appreciate that various modifications, additions
and substitutions are possible, without departing from the scope and spirit of the
invention as disclosed in the accompanying claims.
[0032] Example
[0033] [Example 1]
[0034] In a flask reactor (F1) in a helium atmosphere, 27.6 g (300 mmol) of glycerol and
20.71 g (450 mmol) of formic acid were placed such that formic acid was added in an
amount of 1.5 equivalents relative to 1 equivalent of glycerol, and the temperature of the
reaction mixture was increased to 230°C at a rate of 4.2 °C/min with slow stirring and
then maintained for 2.5 hr, yielding allyl alcohol.
[0035] [Example 2]
[0036] Allyl alcohol was prepared in the same manner as in Example 1, with the
6
exception that the reaction temperature was 240°C.
[0037] [Example 3]
[0038] Allyl alcohol was prepared in the same manner as in Example 1, with the
exception that the reaction temperature was 250°C.
[0039] [Example 4]
[0040] In a flask reactor (F1) in a helium atmosphere, 27.6 g (300 mmol) of glycerol and
13.8 g (300 mmol) of formic acid were placed such that formic acid was added in an
amount of 1.0 equivalent relative to 1 equivalent of glycerol, and the temperature of the
reaction mixture was increased to 230°C with slow stirring and then maintained for 2.5
hr, yielding allyl alcohol.
[0041] [Example 5]
[0042] Allyl alcohol was prepared in the same manner as in Example 4, with the
exception that formic acid was added in an amount of 2.0 equivalents.
[0043] [Example 6]
[0044] Allyl alcohol was prepared in the same manner as in Example 4, with the
exception that formic acid was added in an amount of 0.8 equivalents.
[0045] [Example 7]
[0046] Allyl alcohol was prepared in the same manner as in Example 4, with the
exception that formic acid was added in an amount of 1.2 equivalents.
[0047] [Example 8]
[0048] Allyl alcohol was prepared in the same manner as in Example 4, with the
exception that formic acid was added in an amount of 1.7 equivalents.
[0049] [Comparative Example 1]
[0050] Allyl alcohol was prepared in the same manner as in Example 1, with the
exception that the reaction temperature was 200°C.
[0051] [Comparative Example 2]
[0052] Allyl alcohol was prepared in the same manner as in Example 1, with the
exception that the heating rate was 1.5 °C/min.
[0053] [Comparative Example 3]
[0054] Allyl alcohol was prepared in the same manner as in Example 4, with the
exception that formic acid was added in an amount of 0.60 equivalents.
[0055] [Comparative Example 4]
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[0056] Allyl alcohol was prepared in the same manner as in Example 4, with the
exception that formic acid was added in an amount of 3.0 equivalents.
[0057] In the allyl alcohol preparation processes of Examples 1 to 8 and Comparative
Examples 1 to 4, the formic acid equivalent and the reaction temperature are
summarized in Table 1 below.
[Table 1]
Formic acid equiv.
(relative to 1 equiv. of glycerol)
Reaction temp.
(°C)
Heating rate
(°C/min)
Ex.1 1.5 230 4.2
Ex.2 1.5 240 4.2
Ex.3 1.5 250 4.2
Ex.4 1.0 230 4.2
Ex.5 2.0 230 4.2
Ex.6 0.8 230 4.2
Ex.7 1.2 230 4.2
Ex.8 1.7 230 4.2
C.Ex.1 1.5 200 4.2
C.Ex.2 1.5 230 1.5
C.Ex.3 0.6 230 4.2
C.Ex.4 3.0 230 4.2
[0058] Test Example
[0059] The allyl alcohol and unreacted glycerol concentrations in the above examples
and comparative examples were analyzed using gas chromatography (GC 6890N,
Agilent).
[0060] To this end, as the reactions described in Examples 1 to 8 and Comparative
Examples 1 to 4 progressed, unreacted formic acid, water and allyl alcohol, which are
vaporized from the liquid mixture, were passed through a condenser connected to the
reactor (F1) and then the condensates were collected in a flask (F2) placed at the end of
the condenser. To calculate the yield, after termination of the reaction, 8.29 g (60 mmol)
of calcium carbonate was added in the flask (F2) so as for neutralization and salting out,
and the organic layer was extracted, and the allyl alcohol yield was calculated. Also, to
calculate the glycerol conversion and allyl alcohol selectivity, the sample collected in the
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flask (F2) placed at the end of the condenser was quantitatively analyzed using gas
chromatography (GC 6890N, Agilent). After termination of the reaction for 2.5 hr, the
reactor (F1) was cooled, and unreacted glycerol was quantitatively analyzed using gas
chromatography (GC 6890N, Agilent). As such, allyl alcohol was absent in the reactor
(F1), but formic acid was present in the reactor (F1) and the flask (F2) provided to the
end of the condenser.
[0061] Based on the measurement results as above, the glycerol conversion, allyl
alcohol selectivity, and allyl alcohol yield were calculated using Equations 1 to 3 below.
The results are shown in Table 2 below.
[Equation 1]
reactiomol of glycerol before n
mol of reacted glycerol
Glycerol conversion (%) =100 ´
[Equation 2]
mol of reacted glycerol
mol of produced allyl alcohol
Allyl alcohol selectivity (%) = 100 ´
[Equation 3]
100
(%)
Glycerol conversion Allyl alcohol selectivity
Allyl alcohol yield = ´
[0062] Test Example 1: Effect of temperature on glycerol conversion, allyl alcohol
selectivity, and allyl alcohol yield
[0063] Effect of temperature on the glycerol conversion, allyl alcohol selectivity, and
allyl alcohol yield is shown in Table 2 below.
[Table 2]
Reaction temp.
(°C)
Glycerol
conversion (%)
Allyl alcohol
selectivity (%)
Allyl alcohol
yield (%)
Ex.1 230 95 85 80.7
Ex.2 240 96 74 71.0
Ex.3 250 92 71 65.3
C.Ex.1 200 92 2 1.8
[0064] As shown in Table 2, in Examples 1 to 3 and Comparative Example 1 where
different reaction temperatures were used while the same amount of formic acid was
added, the maximum allyl alcohol yield was obtained at 230°C. As the reaction
9
temperature increased to 250°C, the allyl alcohol selectivity decreased, resulting in
lowering allyl alcohol yield. On the other hand, the allyl alcohol yield of Comparative
Example 1 was very low at a reaction temperature of 200°C.
[0065] Test Example 2: Effect of formic acid equivalent on glycerol conversion,
allyl alcohol selectivity, and allyl alcohol yield
[0066] Effect of formic acid equivalent on the glycerol conversion, allyl alcohol
selectivity, and allyl alcohol yield is shown in Table 3 below.
[Table 3]
Formic acid
equiv.
Glycerol
conversion (%)
Allyl alcohol
selectivity (%)
Allyl alcohol yield
(%)
Ex.1 1.5 95 85 80.7
Ex.4 1.0 84 84 70.6
Ex.5 2.0 99 68 67.3
Ex.6 0.8 72 89 64.1
Ex.7 1.2 90 84 75.6
Ex.8 1.7 97 78 75.7
C.Ex.3 0.6 50 92 46.0
C.Ex.4 3.0 97 38 36.8
[0067] As shown in Table 3, in Examples 1, 4 to 8 and Comparative Examples 3 and 4
where different formic acid equivalents were added while the same reaction temperature
were used, the maximum allyl alcohol yield was obtained at an amount of 1.50
equivalents. In Comparative Example 3 using formic acid in an amount of 0.60
equivalents, the allyl alcohol selectivity was high but the glycerol conversion was low,
and thus the allyl alcohol yield was only 46%. When formic acid was used in an amount
of 3.00 equivalents, the allyl alcohol selectivity was decreased and thus the allyl alcohol
yield was lowered. Also, when formic acid was used in an amount of 0.8 ~ 2
equivalents, the allyl alcohol yield was 60% or more, and when formic acid was used in
an amount of 1.2 ~ 1.7 equivalents, the allyl alcohol yield reached maximum of 75% or
higher.
[0068] Test Example 3: Effect of heating rate on glycerol conversion, allyl alcohol
selectivity, and allyl alcohol yield
[0069] Effect of heating rate on the glycerol conversion, allyl alcohol selectivity, and
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allyl alcohol yield is shown in Table 4 below.
[Table 4]
Heating rate
(°C/min)
Glycerol
conversion (%)
Allyl alcohol
selectivity (%)
Allyl alcohol
yield (%)
Ex.1 4.2 95 85 80.7
C.Ex.2 1.5 89 61 54.2
[0070] As shown in Table 4, in Example 1 and Comparative Example 2 where different
heating rates were applied while the same reaction temperature were used and the same
amount of formic acid was added, both the conversion and the selectivity were decreased
as the heating rate was lower.
[0071] Based on the analytical results of Tables 2 through 4, the allyl alcohol yield can
be remarkably increased within the certain range of the reaction temperature, heating
rate and formic acid equivalent in the method of preparing allyl alcohol according to the
present invention, thereby exhibiting superior effects.
11

CLAIMS
1. A method of preparing allyl alcohol, comprising mixing glycerol with formic
acid in an amount of 0.8 ~ 2 equivalents relative to 1 equivalent of glycerol, and
increasing a reaction temperature to 220 ~ 260°C from room temperature at a heating
rate of 2.0 ~ 7.0 °C/min so that glycerol and formic acid are reacted.
2. The method of claim 1, wherein formic acid is added in an amount of 1.2 ~ 1.7
equivalents.
3. The method of claim 1, wherein the heating rate is 4.0 ~ 7.0 °C/min.
4. The method of claim 1, wherein the reaction temperature is 230 ~ 250°C.
5. The method of claim 1, wherein glycerol and formic acid are reacted without
using a catalyst.
6. The method of claim 1, wherein glycerol and formic acid are reacted in an
inert gas atmosphere.
7. The method of claim 6, wherein the inert gas is helium, nitrogen or argon.
8. The method of claim 1, wherein an allyl alcohol yield is 60% or more.
9. The method of claim 1, wherein an allyl alcohol yield is 75% or more.
10. An allyl alcohol prepared by the method of claim 1.