KR101762414B1 - Preparation method of propylene glycol - Google Patents

Abstract

The present invention relates to a process for producing propylene glycol. More specifically, it comprises reacting a reactant comprising glycerin in the presence of a catalyst comprising Cu, Cr and Ba as active components or a catalyst comprising Cu and Ca as active components in the presence of hydrogen gas.
Such a production method not only has a high conversion rate but also has a high selectivity for propylene glycol, and thus can be usefully used in industrial fields relating to the production of propylene glycol.

Description

PREPARATION METHOD OF PROPYLENE GLYCOL [0002]

The present invention relates to a process for producing propylene glycol.

Among propylene glycol, especially 1,2-propanediol, are widely used as raw materials for pharmaceuticals such as unsaturated polyester resin, cosmetics, ointment, antifreeze, surfactant, and high-polar solvent. Such propylene glycol is mainly produced from propylene oxide.

In recent years, development of renewable energy sources has been actively underway, and as a result, interest in biodiesel has been amplified. Biodiesel is an alternative to petroleum-based diesel oil and is based on renewable resources such as vegetable oils and animal fats. A large amount of glycerin is produced as a by-product in the process of manufacturing such biodiesel, and thus the production of glycerin, a by-product, will gradually increase with the growth of the biodiesel industry.

Meanwhile, the inventors of the present invention completed the present invention while repeating researches on a process for producing propylene glycol using an alternative raw material as a starting material in place of the conventional process for producing propylene glycol from propylene oxide.

Accordingly, the present invention provides a process for producing propylene glycol having high conversion and high selectivity by using glycerin as a reactant.

The present invention provides a process for producing propylene glycol having high conversion and high selectivity.

Specifically, the process for producing propylene glycol according to the embodiment of the present invention comprises the steps of: preparing a catalyst containing Cu, Cr, and Ba as an active ingredient, a catalyst containing Cu and Ca as an active ingredient, and glycerin in the presence of hydrogen gas And reacting the reactants.

On the other hand, unless expressly stated otherwise, some terms used throughout this specification are defined as follows.

Throughout this specification, "reactor effective volume" is defined as "total reactor volume" or "volume of catalyst loaded in reactor ". The term "LHSV" as used throughout the present specification means "Liquid Hourly Space Velocity". In particular, in the present invention relating to the production of propylene glycol, "LHSV" is defined as "space velocity of glycerin" Volume of glycerin per volume ". Also, the catalyst containing the chemical element X, the chemical element Y and the chemical element Z as the active component means that each of the compounds of the active ingredient of the catalyst contains the chemical element X, the chemical element Y, Z, or each of the compounds of the active component of the catalyst is the above chemical elements.

Reacting a reactant comprising glycerin in the presence of a catalyst comprising Cu, Cr and Ba as active components and hydrogen gas, or in the presence of hydrogen and a catalyst comprising Cu and Ca as active components The present inventors have found that the conversion of glycerin is not only high but also the selectivity of propylene glycol is high, thus completing the present invention.

In the reaction step, specifically, dehydration of glycerin to obtain acetol; And hydrogenating the acetol to obtain propylene glycol. On the other hand, preferably the reaction steps can take place continuously in one reactor. The specific reaction scheme is as follows.

Reaction Scheme

Examples of the impurities that can be generated in the reaction scheme include acetone, ethanol, dipropylene glycol, 1-propanol, propylene glycol ethyl ether, A compound having a boiling point of not higher than 150 占 폚, and a compound having a boiling point of 190 占 폚 or higher such as ethylene glycol or 1,3-propanediol. As the intermediate, acetol (acetal) as shown in the above reaction scheme can be mentioned.

On the other hand, when propylene glycol was prepared by the above-described method of the present invention, it was confirmed that the content of impurities as described above was small and propylene glycol selectivity was high. For reference, throughout this specification, propylene glycol as the final target compound is defined as "1,2-propanediol" unless otherwise defined.

The catalyst containing Cu, Cr and Ba as the active component or the catalyst containing Cu and Ca as the active component used in the production method of the above embodiment may include a carrier, But is not limited to, the most widely used carrier such as alumina or silica. On the other hand, when the reaction proceeds in a continuous reactor, such a reaction can be preferably used since conversion and selectivity are higher. An example of a continuous reactor that can be used for the production of propylene glycol is shown in FIG. 1, but the present invention is not limited to the continuous reactor shown in FIG.

At this time, the catalyst comprising Cu, Cr, and Ba as the active ingredient or the catalyst containing Cu and Ca as the active ingredient is not limited as long as it is a catalyst containing such a metal substance, but more specifically, copper _{(copper Chromite, Cu 2 Cr 2} O 5), copper oxide (copper oxide, CuO) and barium chromate (barium chromate, BaCrO ₄₎ a catalyst comprising as an active ingredient; A catalyst comprising copper oxide (CuO) and calcium oxide (CaO) as active ingredients; And at least one selected from the group of catalysts containing Cu, Cr, and Ba as active components. As shown in the following Examples and the like, the inventors of the present invention have found that the conversion of glycerin is 95% or more and the selectivity of propylene glycol is at least 60% or more, by using such a catalyst or the like.

More preferably, the catalyst comprises 35 to 50 parts by weight of copper chromate (Cu ₂ Cr ₂ O ₅ ), 10 to 20 parts by weight of copper oxide (CuO) with respect to 100 parts by weight of the total catalyst, ) And 5 to 15 parts by weight of barium chromate (BaCrO ₄ ) as an active ingredient; A catalyst comprising 40 to 50 parts by weight of copper oxide (CuO) and 5 to 15 parts by weight of calcium oxide (CaO) as an active ingredient per 100 parts by weight of the total catalyst content; And at least one selected from the group consisting of 30 to 45 parts by weight of Cu, 25 to 35 parts by weight of Cr, and 1 to 10 parts by weight of Ba as the active ingredient, based on 100 parts by weight of the total catalyst.

In addition, the catalyst may further contain a carrier within a conventional content range in order to secure structural stability. The kind of the carrier is not particularly limited because it can use a carrier which is customary in the technical field to which the present invention belongs. Preferably, the support may be at least one selected from alumina and silica. More preferably copper chromite _{(Copper Chromite, Cu 2 Cr 2} O 5), the case of a catalyst containing a copper oxide (Copper Oxide, CuO) and chromic acid barium (Barium Chromate, BaCrO ₄₎ as an active ingredient, the alumina body carrying , And a catalyst containing copper oxide (CuO) and calcium oxide (CaO) as an active component can be used as a support. On the other hand, as the catalyst containing Cu, Cr and Ba as an active component, silica or alumina can be used as a support.

The catalyst is most preferably used in an amount of 35 to 50 parts by weight of copper chromate (Cu ₂ Cr ₂ O ₅ ), 10 to 20 parts by weight of copper oxide (CuO ) And 5 to 15 parts by weight of barium chromate (BaCrO ₄ ) as an active ingredient, and the balance comprising an alumina carrier; (CuO) and 5 to 15 parts by weight of calcium oxide (CaO) as an active ingredient in an amount of 40 to 50 parts by weight based on 100 parts by weight of the total catalyst, catalyst; And 30 to 45 parts by weight of Cu, 25 to 35 parts by weight of Cr, and 1 to 10 parts by weight of Ba as active components relative to 100 parts by weight of the total catalyst, and the balance being a catalyst group containing silica or alumina carrier It can be one or more selected.

The method for producing the catalyst according to the present invention is not particularly limited, and can be manufactured by a person having ordinary skill in the art.

The above-described catalyst may be supplied to the reactor through the activation step before the reaction. In the case of using the catalyst after the activation step, it is possible not only to prevent the temperature rise of the catalyst during the reaction, And the like can be prevented.

Specifically, the above-mentioned catalyst and the like are reduced in the presence of hydrogen and nitrogen gas at a temperature of less than 210 캜; And in the presence of hydrogen gas at a temperature of 180-220 < 0 > C. At this time, the above-mentioned activation step may be carried out by injecting hydrogen gas corresponding to 1 to 3 times the catalyst volume at a temperature of 190 to 210 DEG C, more preferably. It has been found that the catalyst can be activated under such conditions to increase the selectivity of propylene glycol and also to delay the deactivation of the catalyst.

The reaction can be carried out by supplying 1 to 50 moles of hydrogen gas per mole of glycerin. When the amount of hydrogen gas supplied per mole of glycerin is less than 1 mole, the hydrogenation reaction does not occur completely after dehydration of glycerin, If the amount of the hydrogen gas supplied per 1 mole of glycerin is more than 50 mol, the excess hydrogen gas does not cause a uniform temperature distribution in the reactor, so that the conversion rate may be lowered, and the cost of recycling excess hydrogen may be lowered The economy may be lowered. More preferably 1 to 40 moles of hydrogen gas per mole of glycerin can be supplied, and most preferably, 1 to 32 moles of hydrogen gas per mole of glycerin can be supplied to the reaction.

At this time, it is preferable that the reaction is carried out at a temperature of 200 to 260 DEG C and a pressure of 1 to 50 kg / cm < ² >

That is, the reaction temperature is preferably 200 ° C. or higher to supply the minimum reaction activation energy, and when the temperature is high, decomposition of glycerin and sintering of the catalyst may occur. More preferably, the reaction may occur at 210 to 250 ° C, most preferably at 230 to 250 ° C.

The reaction pressure is preferably 1 kg / cm < ² > Or more, and it is preferably 50 kg / cm ² or less in consideration of economical efficiency such as cost for maintaining high pressure and synergistic effect of conversion ratio. More preferably, the reaction pressure is 1 kg / cm < ² > To 40 kg / cm < ² > And most preferably 2 kg / cm < ² > To 30 kg / cm ² Lt; / RTI >

Depending on the type of catalyst selected, the reaction temperature and pressure conditions can be adjusted within the ranges described above.

Further, the reaction is preferably conducted so as to provide a space velocity (LHSV) of glycerol from 0.1 to 2.0 hr ^-1 in a continuous reactor. When the space velocity of glycerin held in the continuous reactor is less than 0.1 hr ^-1, a note of the amount of the reactants that are introduced into the reactor is difficult to achieve economical production, under the conditions that the space velocity of the glycerol exceeds 2.0 hr ^-1 If a continuous reaction is carried out, the reactant flow rate in the reactor may be too fast to reduce the conversion of the reactants. More preferably, the space velocity of glycerin may be from 0.1 to 1.5 hr < ^-1 >, and most preferably from 0.1 to 1.0 hr <" ¹ >.

On the other hand, reaction results according to the specific catalyst types within the range of the above-described reaction conditions are as follows.

When the reaction is carried out in the presence of a catalyst containing copper chromate (Cu ₂ Cr ₂ O ₅ ), copper oxide (CuO) and barium chromate (BaCrO ₄ ) as an active ingredient, It was confirmed that the conversion of glycerin was 95% or more and the selectivity of propylene glycol was 75% or more.

When the reaction is carried out in the presence of a catalyst containing copper oxide (CuO) and calcium oxide (CaO) as an active ingredient, the conversion of glycerin is 95% or more, the selectivity of propylene glycol is 80% The conversion and the selectivity are high at the same time, and it is expected to be usefully applied to industrial fields related to the production of propylene glycol.

It was confirmed that the conversion of glycerin was 95% or more and the selectivity of propylene glycol was 60% or more when proceeding in the presence of a catalyst containing Cu, Cr, and Ba as active components.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the conversion of glycerin and the selectivity of propylene glycol are high, and it is expected that they can be usefully used in industry related to the production of propylene glycol.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a simplified illustration of a continuous reactor in which propylene glycol can be prepared according to one embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to specific examples in order to facilitate understanding. However, the following examples are only for the purpose of clarifying the present invention, and the present invention is not limited thereto.

First, according to Examples to be described later, a step of reacting a reaction product containing glycerin in the presence of a catalyst comprising Cu, Cr and Ba as an active ingredient or a catalyst containing Cu and Ca as an active ingredient in the presence of hydrogen gas To prepare propylene glycol.

On the other hand, the composition after the reaction was analyzed by gas chromatography under the following conditions.

A) Analytical instrument: Gas chromatograph (HP-6890N)

B) Column: FFAP (polarity) 25 m * 0.2 mm * 030 탆

C) Analysis instrument conditions:

i) Initial Temperature: 80 ° C

ii) Initial Time: 6 min

iii) Rate of temperature rise (Rate): 7 DEG C / min

iv) Final Temperature: 240 ° C

v) Inlet temperature: 250 DEG C

vi) Detector Temperature: 250 ° C

Example  One: Cu ₂ Cr ₂ O ₅ , CuO  And BaCrO ₄ In the presence of a catalyst comprising as an active ingredient, the production of propylene glycol from glycerin

A 3/4 inch diameter, 10 inch long continuous reactor was prepared. Cu-1230 from BASF was prepared as a catalyst containing Cu ₂ Cr ₂ O ₅ , CuO and BaCrO ₄ as an active ingredient. The prepared Cu-1230 was reduced under the condition of not exceeding 210 캜 for 3 to 4 hours using nitrogen and hydrogen to prevent the temperature rise of the catalyst, and then activated by flowing hydrogen gas at 200 캜 twice as much as the catalyst volume Then, the above-mentioned reactor was filled with 50 cc.

The continuous reaction was carried out under the same conditions as those shown in Table 1 below to obtain the products having the compositions shown in Table 2. The conversions and the selectivities were shown in Table 3 after completion of the reaction.

Reaction conditions Temperature (℃) Pressure (kg / cm ² ) The reaction mole ratio (glycerin: H ₂ ) LHSV ^(share) (hr ^-1 ) Example 1-1 250 3 1: 3 1.0 Examples 1-2 250 3 1: 8 0.3 Example 1-3 250 3 1: 32 0.1 Examples 1-4 250 30 1: 8 0.5 LHSV: Liquid Hourly Space Velocity (LHSV)

After completion of the reaction, composition analysis (% by weight) L'T ^{Co., Ltd.} Acetol 1,2-PDO Hvy ^{Co., Ltd.} Gly ^Co. Example 1-1 4.51 11.18 77.52 6.79 0.00 Examples 1-2 4.44 7.88 82.96 4.72 0.00 Example 1-3 4.29 4.57 86.87 4.27 0.00 Examples 1-4 14.26 0.45 78.59 6.70 0.00 (Note) L'T: A liquid such as acetone, ethanol, dipropylene glycol, 1-propanol, propylene glycol ethyl ether, Indicates an impurity having a boiling point.
Hvy: Represents an impurity having a boiling point of 190 ° C or higher, such as ethylene glycol and 1,3-propanediol.

After termination of the reaction, conversion and selectivity Conversion Rate (%) Selectivity of 1,2-PDO (%) Selectivity of acetol
(%) Selectivity of 1,2-PDO and acetol (%) Example 1-1 100.00 77.52 11.18 88.70 Examples 1-2 100.00 82.96 7.88 90.84 Example 1-3 100.00 86.87 4.57 91.44 Examples 1-4 100.00 78.59 0.45 79.04

As shown in Tables 2 and 3, a reaction product containing glycerin was reacted with a catalyst containing Cu ₂ Cr ₂ O ₅ , CuO and BaCrO ₄ as an active ingredient in the presence of hydrogen gas to prepare 1,2-propylene glycol Was found to have a high conversion rate of 100% and a selectivity of 1,2-propylene glycol of at least 77.52%.

Example  2: CuO  And CaO In the presence of a catalyst comprising as an active ingredient propylene glycol production from glycerin

A 3/4 inch diameter, 10 inch long continuous reactor was prepared. Cu-0860 from BASF was prepared as a catalyst containing CuO and CaO as active components. The prepared Cu-0860 was subjected to reduction under the condition of not exceeding 210 캜 for 3 to 4 hours by using nitrogen and hydrogen to prevent the temperature rise of the catalyst, and then activated by flowing hydrogen gas at 200 캜 twice the catalyst volume Thereafter, 48 cc of the above-mentioned reactor was charged.

Continuous reaction was carried out under the same conditions as those shown in Table 4 below to obtain products having the compositions shown in Table 5. The conversions and the selectivities were shown in Table 6 after completion of the reaction.

Reaction conditions Temperature (℃) Pressure (kg / cm ² ) The reaction mole ratio (glycerin: H ₂ ) LHSV ^(share) (hr ^-1 ) Example 2 250 3 1: 8 0.3 LHSV: Liquid Hourly Space Velocity (LHSV)

After completion of the reaction, composition analysis (% by weight) L'T ^{Co., Ltd.} Acetol 1,2-PDO Hvy ^{Co., Ltd.} Gly ^Co. Example 2 6.59 2.94 84.32 6.15 0.00 (Note) L'T: A liquid such as acetone, ethanol, dipropylene glycol, 1-propanol, propylene glycol ethyl ether, Indicates an impurity having a boiling point.
Hvy: Represents an impurity having a boiling point of 190 ° C or higher, such as ethylene glycol and 1,3-propanediol.

After termination of the reaction, conversion and selectivity Conversion Rate (%) Selectivity of 1,2-PDO (%) Selectivity of acetol
(%) Selectivity of 1,2-PDO and acetol (%) Example 2 100.00 84.32 2.94 87.26

As shown in Tables 5 and 6, the reaction of reacting glycerin-containing reactants in the presence of hydrogen gas and a catalyst containing CuO and CaO as active components to obtain 1,2-propylene glycol has a conversion rate of 100 %, And the selectivity of 1,2-propylene glycol was also very high at 84.32%.

Example  3: Cu , Cr , Ba In the presence of a catalyst comprising as an active ingredient propylene glycol production from glycerin

A 3/4 inch diameter, 10 inch long continuous reactor was prepared. KL-1970 from Shell was prepared as a catalyst containing Cu, Cr and Ba as active ingredients. The prepared KL-1970 was subjected to reduction at 210 ° C for 3 to 4 hours using nitrogen and hydrogen to prevent the temperature rise of the catalyst, and then activated by flowing hydrogen gas at 200 ° C twice the catalyst volume Then, the reactor described above was filled with 45 cc.

The continuous reaction was carried out under the same conditions as those shown in Table 7 below to obtain the products of the compositions shown in Table 8. The conversions and the selectivities were shown in Table 9 after completion of the reaction.

Reaction conditions Temperature (℃) Pressure (kg / cm ² ) The reaction mole ratio (glycerin: H ₂ ) LHSV ^(share) (hr ^-1 ) Example 3 250 3 1: 2 1.0 LHSV: Liquid Hourly Space Velocity (LHSV)

After completion of the reaction, composition analysis (% by weight) L'T ^{Co., Ltd.} Acetol 1,2-PDO Hvy ^{Co., Ltd.} Gly ^Co. Example 3 5.95 22.97 64.86 6.22 0.00 (Note) L'T: A liquid such as acetone, ethanol, dipropylene glycol, 1-propanol, propylene glycol ethyl ether, Indicates an impurity having a boiling point.
Hvy: Represents an impurity having a boiling point of 190 ° C or higher, such as ethylene glycol and 1,3-propanediol.

After termination of the reaction, conversion and selectivity Conversion Rate (%) Selectivity of 1,2-PDO (%) Selectivity of acetol
(%) Selectivity of 1,2-PDO and acetol (%) Example 3 100 64.86 22.97 87.83

As shown in Tables 8 and 9, by reacting a reactant containing glycerin in the presence of a catalyst containing Cu, Cr, and Ba as an active ingredient and hydrogen gas, a reaction for obtaining 1,2- , The conversion rate was 100%, and the selectivity of 1,2-propylene glycol was at least 64.86%.

Example  4: Catalyst Life  Test

On the other hand, the Cu-1230 catalyst used in Example 1 was subjected to a life test. The reaction conditions are as follows. Conversion ratio, 1,2-PDO selectivity, and product composition are shown in Table 10 below.

Temperature; 250 ℃

pressure; 3 kg / cm ² (H ₂ pressure)

Liquid Hourly Space Velocity (LHSV); 0.3 hr ^-1

Feed mole ratio; Glycerin: H ₂ = 1: 8

Reactor (diameter * height); 3/4 inch * 10 inch

Activation; In order to prevent the temperature rise of the catalyst, the catalyst was reduced under the condition of not exceeding 210 캜 for 3 to 4 hours by using nitrogen and hydrogen. Thereafter, while feeding H ₂ corresponding to twice the catalyst volume at 200 캜, Respectively.

On the other hand, the operation was carried out for sixteen hours a day for sixteen hours, with an average conversion rate of 100% per day for six hours. The reaction time in Table 10 represents the cumulative operation time. When the number of reaction days was exceeded, the catalyst was used the previous day, not newly charged, and the amount of the initially charged catalyst was 50 cc.

reaction
Days
(day) reaction
time
(hr) Conversion Rate 1,2-PDO
Selectivity of
(%) Selectivity of acetol
(%) Selectivity of 1,2-PDO and acetol
(%) After completion of the reaction, composition analysis (% by weight) L'T Acetol 1,2-PDO Hvy ^{Co., Ltd.} Gly ^Co. One 6 100.00 73.79 2.93 76.72 12.98 2.93 73.79 10.30 0.00 2 12 100.00 77.62 3.30 80.92 10.28 3.30 77.62 8.80 0.00 3 18 100.00 79.78 3.63 83.41 8.65 3.63 79.78 7.94 0.00 4 24 100.00 81.27 3.76 85.03 7.79 3.76 81.27 7.18 0.00 5 30 100.00 81.23 3.32 84.55 8.55 3.32 81.23 6.90 0.00 6 36 100.00 81.84 3.32 85.16 8.02 3.32 81.84 6.82 0.00 7 42 100.00 78.65 4.81 83.46 8.99 4.81 78.65 7.55 0.00 8 48 100.00 80.27 4.84 85.11 8.06 4.84 80.27 6.83 0.00 9 54 100.00 79.95 4.48 84.43 8.38 4.48 79.95 7.19 0.00 10 60 100.00 79.98 5.05 85.03 7.62 5.05 79.98 7.35 0.00 11 66 100.00 80.23 4.24 84.47 8.55 4.24 80.23 6.98 0.00 12 72 100.00 81.03 4.28 85.31 7.75 4.28 81.03 6.94 0.00 13 78 100.00 81.42 4.80 86.22 7.17 4.80 81.42 6.61 0.00 14 84 100.00 81.90 4.94 86.84 6.83 4.94 81.90 6.33 0.00 15 90 100.00 81.57 4.92 86.49 6.66 4.92 81.57 6.85 0.00 16 96 100.00 81.47 5.43 86.90 6.29 5.43 81.47 6.81 0.00 17 102 100.00 81.38 4.42 85.80 7.37 4.42 81.38 6.83 0.00 18 108 100.00 81.35 5.42 86.77 6.71 5.42 81.35 6.52 0.00 Average 100.00 80.26 4.33 84.59 8.15 4.33 80.26 7.26 0.00 (Note) L'T: A liquid such as acetone, ethanol, dipropylene glycol, 1-propanol, propylene glycol ethyl ether, Indicates an impurity having a boiling point.
Hvy: Represents an impurity having a boiling point of 190 ° C or higher, such as ethylene glycol and 1,3-propanediol.

As shown in Table 10, when the conversion was 100%, it was confirmed that the activity of the catalyst did not deteriorate and maintained. Further, when the continuous operation is continued under such a catalyst condition of Cu-1230, when the conversion is close to 100% and the content of glycerin remaining in the reactor is almost zero, deactivation of the catalyst is not observed .

Therefore, in accordance with the above-described embodiments of the present invention, a catalyst comprising Cu, Cr, and Ba as an active ingredient or a catalyst containing Cu and Ca as an active ingredient, and a catalyst containing, as a starting material, glycerin in the presence of hydrogen gas, It is expected that the process for producing propylene glycol can be usefully used in industrial fields related to the production of propylene glycol.

Claims (7)

(Copper Chromite, Cu ₂ Cr ₂ O ₅ ), 10 to 20 parts by weight of copper oxide (CuO), and 5 to 15 parts by weight of chromic acid based on 100 parts by weight of the total amount of the catalyst A catalyst comprising barium chromate (BaCrO ₄ ) as an active ingredient; A catalyst comprising 40 to 50 parts by weight of copper oxide (CuO) and 5 to 15 parts by weight of calcium oxide (CaO) as an active ingredient per 100 parts by weight of the total catalyst content; And at least one catalyst selected from the group consisting of 30 to 45 parts by weight of Cu, 25 to 35 parts by weight of Cr and 1 to 10 parts by weight of Ba as an active ingredient with respect to 100 parts by weight of the total catalyst, Reacting a reactant comprising glycerin in the presence of a catalyst. The method according to claim 1,
The reaction step may include dehydration of glycerin to obtain acetol; And
And hydrogenating the acetol to obtain propylene glycol. delete The method according to claim 1,
Wherein the catalyst comprises at least one carrier selected from the group consisting of alumina and silica. The method according to claim 1,
Wherein the reaction is carried out by supplying 1 to 50 moles of hydrogen gas per 1 mole of glycerin. The method according to claim 1,
Wherein the reaction is carried out at a temperature of 200 to 260 DEG C and a pressure of 1 to 50 kg / cm < ² >. The method according to claim 1,
Wherein the reaction proceeds such that the space velocity of glycerin in the continuous reactor is from 0.1 to 2.0 hr <" ¹ >.

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