JP2010155183A - Method for producing acrolein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for vapor-phase dehydration of glycerin, which is used in a vapor-phase dehydration reaction of glycerin to produce acrolein and has high selectivity of acrolein, and to provide a new method for producing acrolein, in which glycerin is used a raw material in the coexistence of the catalyst for vapor-phase dehydration of glycerin. <P>SOLUTION: The catalyst for vapor-phase dehydration of glycerin contains tantalic acid, which catalyst can allow acrolein to be produced with high selectivity by the vapor-phase dehydration reaction by using glycerin as a raw material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a catalyst for vapor phase dehydration of glycerin and a method for producing acrolein using this catalyst.

  Acrolein is a useful compound used as a raw material for acrolein derivatives such as 1,3-propanediol, 1,2-propanediol, methionine, acrylic acid, 3-methylpropionaldehyde, and a water-absorbing resin.

  Acrolein is widely industrially produced by a catalytic gas phase oxidation reaction using a catalyst containing Mo and Bi from propylene. On the other hand, in recent years, a process for producing acrolein by a dehydration reaction using an acid catalyst using glycerol as a raw material has been disclosed.

For example, as a method for producing acrolein from glycerin, a solid acid catalyst having an acid strength function H ₀ of +2 or less (for example, phosphoric acid supported on an aluminum oxide carrier) and glycerin / containing 10 to 40% by mass of glycerin / A method of contacting a water mixture under conditions of 250 ° C. to 340 ° C. (see Patent Document 1), a method using a solid strong acid catalyst having an acid strength function H ₀ of −9 to −18, and tantalum oxide Ta ₂ O ₅ (See Patent Document 2) and the like.

Japanese Patent Laid-Open No. 06-211724 As described above, a production method for obtaining acrolein from a dehydration reaction of glycerin is known, but since a by-product such as 1-hydroxyacetone, acetaldehyde and propionaldehyde is generated, acrolein is highly selective. Could not be manufactured.

  In view of the above circumstances, an object of the present invention is to provide a catalyst for vapor phase dehydration of glycerin having high acrolein selectivity and a method for producing acrolein from glycerin in the presence of the catalyst.

  An object of the present invention is to provide a catalyst for use in the production of acrolein by vapor phase dehydration reaction of glycerin, which is a catalyst for vapor phase dehydration of glycerin containing tantalum acid.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that acrolein can be produced by gas-phase dehydration reaction of glycerin using a glycerin gas-phase dehydration catalyst containing tantalic acid, and the present invention has been completed. .

That is, the following method was invented as means for solving the above-mentioned problems.
(1) A catalyst used in a method for producing acrolein by vapor phase dehydration reaction of glycerin, and a catalyst for glycerin gas phase dehydration containing tantalic acid (2) Moisture contained in the tantalic acid is 0.1% by mass or more The catalyst for glycerin gas phase dehydration according to (1), wherein the acid amount distribution of the tantalic acid is -8.2 <H ₀ ≦ −3.0 Hammett acid strength H ₀ The glycerin gas phase dehydration catalyst according to (1) or (2), wherein the acid amount in the range represented by the formula (1) is 0.001 mmol / g or more when measured by a titration method (4) The catalyst for glycerin gas phase dehydration according to (1) to (3), wherein the catalyst containing tantalic acid is obtained by calcining a hydroxide of tantalum at 50 to 600 ° C. Dehydrate glycerin in the presence of coexistence A method for producing acrolein, a manufacturing method of acrolein, wherein the catalyst is glycerin vapor phase dehydration catalyst according to any one of (1) to (4).
(6) The method for producing acrolein according to (5), wherein at least a part of glycerin in the dehydration reaction product is recovered and used as a raw material.

  According to the present invention, acrolein can be obtained with high selectivity using glycerin as a raw material in the presence of a glycerin gas phase dehydration catalyst containing tantalum acid.

  The present invention is a catalyst used in a method for producing acrolein by vapor phase dehydration reaction of glycerin, which is a catalyst for vapor phase dehydration of glycerin containing tantalum acid.

The tantalum acid of the present invention is a solid acid, also called hydrous tantalum, and the details of its properties and structure are not clear, but it is amorphous or has a low degree of crystallization, and Ta ₂ O ₅ .nH ₂ O (0 <N). The value of n showing a suitable catalytic action in the present invention is preferably 0.0245 or more, more preferably 0.128 or more, more preferably 0.245 or more. N is preferably 2.45 or less, and more preferably 2.21 or less. The value of n can be adjusted by changing the tantalum acid production method, specifically, the firing temperature and / or time.

  When the value of n is converted into a moisture content, the tantalum acid of the present invention is not particularly limited as long as the moisture content is 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass. % Or more. Even if the amount of tantalum acid is too large, the catalyst performance of increasing the selectivity of acrolein may not be obtained, and it is preferably 10% by mass or less. More preferably, it is 9 mass% or less.

A usual measuring method can be used for the measuring method of acid strength and acid amount. For example, an n-butylamine titration method using a Hammett indicator (Johnson method or Benesi method) can be used. The tantalum acid of the present invention is 0.001 mmol when the acid amount in the range represented by Hammett acid strength H ₀ having an acid amount distribution of −8.2 <H ₀ ≦ −3.0 is measured by a titration method. / G or more. More preferably, it is 0.01 mmol / g or more. Furthermore, when the acid amount in the range represented by Hammett's acid strength H _{0 in} which the acid amount distribution is −3.0 <H ₀ ≦ + 6.8 is measured by a titration method, it should be 0.05 mmol / g or more. It is characterized by. More preferably, it is 0.1 mmol / g. Tantalum acid satisfying the above acid amount is suitable as a glycerol vapor phase dehydration catalyst.

The tantalum acid of the present invention is characterized by a BET specific surface area of 50 to 250 m ² / g. When it has a BET specific surface area in this range, it is suitable as a glycerol vapor phase dehydration catalyst catalyst. Preferably it is 200 m < ² > / g or less, More preferably, it is 150 m < ² > / g or less.

The tantalum acid preparation method can be obtained by heat-treating its precursor tantalum hydroxide. Examples of the method for preparing tantalum hydroxide include a method of hydrolyzing a pentavalent tantalum halide such as TaCl ₅ , TaBr ₅ , TaI ₅ , TaF ₅ or TaOCl ₃ . Specifically, TaCl ₅ is slowly added to aqueous ammonia and then heated to generate a precipitate. Alternatively, TaCl ₅ is dissolved in alcohol or concentrated hydrochloric acid or dispersed in water, and then hot water, ammonia water or a basic solution such as an aqueous solution such as potassium hydroxide or sodium hydroxide is added to A method for producing a precipitate of tantalum oxide is mentioned. Further, a method of hydrolyzing a pentavalent tantalum alkoxide or an alkoxide containing halogen, a method of hydrolyzing a trivalent tantalum halide such as TaBr ₃ to produce tantalum hydroxide, and a tantalum oxide ( This refers to a substance that does not contain hydration water.) Ta ₂ O ₅ is melted with alkali metal hydroxide or carbonate, sulfate, pyrosulfate, etc. to hydrolyze to obtain tantalum hydroxide. There is a way. Among these, tantalum acid prepared by a method in which TaCl ₅ is slowly added to aqueous ammonia and then heated to produce a precipitate is preferable because of its high catalytic activity.

The tantalum hydroxide obtained by the above method does not have sufficient solid acidity as it is, and is fired after washing with acid and / or water. In the present invention, the tantalum hydroxide is baked at 50 to 600 ° C. When calcined at this temperature, when the acid amount in the range represented by Hammett acid strength H ₀ of the above-mentioned acid amount distribution of −8.2 <H ₀ ≦ −3.0 is measured by a titration method, This is because the tantalum acid is 001 mmol / g or more. The firing temperature is preferably 100 ° C. or higher. A preferable upper limit temperature is 600 ° C. or lower, and more preferably 500 ° C. or lower. The higher the firing temperature, the smaller the amount of water contained in the tantalate, and the smaller the BET specific surface area.

  The glycerin gas phase dehydration catalyst only needs to contain tantalum acid, may be singly or supported on a carrier, and may be mixed with a conventionally known catalyst.

  A conventionally known catalyst includes a solid acid catalyst. For example, (a) crystalline metallosilicate, (b) metal oxide, (c) clay mineral, (d) mineral acid supported on an inorganic carrier, (e) metal salt of phosphoric acid or sulfuric acid and the like Examples thereof include those supported on an inorganic carrier such as α-alumina, silica, zirconium oxide, and titanium oxide.

As the crystalline metallosilicate of the above (a), one or more elements selected from Al, B, Fe, Ga and the like are T atoms, and LTA, CHA, FER, MFI, MOR, BEA, Some have a crystal structure such as MTW. Examples of the metal oxide (b) include single metal oxides such as Al ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , and V ₂ O ₅ ; SiO ₂ —Al ₂ O ₃ , SiO ₂ —TiO ₂ , And composite oxides such as TiO ₂ —WO ₃ and WO ₃ —ZrO ₂ . Examples of the clay mineral (c) include bentonite, kaolin, and montmorillonite. Examples of the above-mentioned mineral acid (d) supported on an inorganic carrier include those obtained by supporting a mineral acid such as phosphoric acid and sulfuric acid on an inorganic carrier such as α-alumina, silica, zirconium oxide, and titanium oxide. . Examples of the metal salt of phosphoric acid or sulfuric acid (e) include MgSO ₄ , Al ₂ (SO ₄ ) ₃ , K ₂ SO ₄ , AlPO ₄ , Zr ₃ (PO ₄ ) _{4 and the} like.

  Examples of other solid acid catalysts include catalysts disclosed in WO 2006/087083 and WO 2006/087084 (zirconium oxide carrying phosphoric acid, sulfuric acid, or tungsten oxide).

  The carrier may be any carrier that is usually used as a catalyst carrier such as alumina, silica, zirconia, and titania, and may be supported on the solid acid catalyst or the solid acid catalyst.

  The shape of the catalyst is not limited and is preferably used in a spherical shape, a columnar shape, a ring shape, a bowl shape, or the like. When the above-mentioned substance is in powder form, it may be molded by itself, or may be molded by adding a binder component such as alumina sol or silica sol. It may be used by applying to the surface.

  The present invention is a method for producing acrolein using glycerin as a raw material in the presence of the catalyst. More preferred is a method for producing acrolein by vapor phase dehydration reaction in which glycerin is vaporized to form a gas and the gas is brought into contact with a catalyst.

  The glycerin used as a raw material in the present invention may be any of a purified product, a crude product, and an aqueous solution. It may be glycerin with a purity of 100% or a mixture with water. In the present invention, when a mixture of glycerin and water is used as a raw material, the content of water is preferably 70% by mass or less. If it exceeds 70% by mass, it will take a lot of energy to vaporize, and it will also be economically disadvantageous because of the enormous cost of wastewater treatment, and when the method for producing acrolein of the present invention is carried out industrially It becomes an obstacle. More preferably, the water content is 50% by mass or less, and further preferably 30% by mass or less.

  In the present invention, at least a part of glycerin in the dehydration reaction product can be recovered and used as a raw material. In the dehydration reaction in the present invention, since the conversion rate of glycerin is low, the yield of acrolein can be increased by recovering at least a part of unconverted glycerin and mixing it with only recovered glycerin or new glycerin. Can do. Even when the recovered glycerin is used, it is not necessary to change the reaction conditions in particular, and the reaction can be performed under the same reaction conditions as for new glycerin alone.

  In the present invention, a reactor arbitrarily selected from a fixed bed reactor, a moving bed reactor, a fluidized bed reactor and the like can be used, and it is preferable to use a fixed bed reactor capable of easily producing acrolein.

  When the activity of the catalyst is lowered, the catalyst can be regenerated by bringing the catalyst into contact with the regeneration gas at a high temperature. Here, the “regeneration gas” is a gas containing an oxidizing gas such as oxygen. The method of bringing the catalyst into contact with the regeneration gas containing the oxidizing gas is a method in which the regeneration gas is brought into contact with the catalyst taken out from the reactor; the regeneration is performed in the same reactor as the reactor in which the glycerol dehydration reaction is performed. There is no particular limitation such as a method of circulating gas; In the latter method, the regeneration gas is circulated in such a way that when acrolein is produced using a fixed bed reactor, troubles such as removal of the catalyst from the reactor and recharging of the catalyst into the reactor are required. Recommended because it doesn't cost.

  When oxygen is used as the oxidizing gas in the regeneration of the catalyst, it is inexpensive to use oxygen in the air. In addition, an inert gas such as nitrogen, carbon dioxide, or water vapor may be accompanied with oxygen. In particular, when there is a concern about rapid heat generation due to contact between air and the catalyst, it is recommended to use an inert gas in order to adjust the oxygen concentration. Before and after the catalyst regeneration treatment, purging with an inert gas such as nitrogen may be performed for the purpose of removing excess organic matter remaining in the regeneration treatment system and oxygen mixed during catalyst filling.

  The gas phase dehydration reaction temperature in the production of acrolein according to the present invention usually indicates a set temperature of a heat medium or the like for controlling the temperature of the reactor. The temperature may be changed as appropriate according to changes in the activity of the catalyst and reaction conditions. The reaction temperature may be 200 to 500 ° C, preferably 250 to 450 ° C, and more preferably 300 to 400 ° C. A low reaction temperature is not preferable because the conversion rate of glycerin is low and the production of acrolein is substantially reduced. On the other hand, if the reaction temperature is too high, the yield of acrolein is greatly reduced, which is not preferable.

  The pressure of the raw material gas at the inlet of the reactor is not particularly limited, and is appropriately set based on a balance between an economic viewpoint such as pressure resistance of the reactor and catalyst performance. This pressure is usually 0.1 kPa or more, preferably 0.5 kPa or more, and more preferably 1 kPa or more. The upper limit of the pressure of the raw material gas is not limited as long as the raw material gas at the reactor inlet is a gas, but is usually 1 MPa or less, preferably 500 kPa or less, more preferably 300 kPa or less, and further preferably 200 kPa. It is as follows. At a pressure of 0.1 kPa or less, an effect sufficient to meet the equipment cost of a highly sensitive reactor and the operation cost of the manufacturing apparatus cannot be obtained, and it may be difficult to collect acrolein. In particular, there is a concern that the yield of acrolein may decrease.

The space velocity (hereinafter sometimes referred to as “space velocity” and “GHSV”) at the reactor inlet of the raw material gas including the total amount of glycerin and dilution gas is preferably 100 to 10,000 hr ⁻¹ . Preferably, it is 5000 hr ⁻¹ or less, and 4000 hr ⁻¹ or less is more preferable for producing acrolein economically and with high efficiency.

  The concentration of glycerin in the raw material gas is not particularly limited and can be selected in the range of 0.1 to 100 mol%. In view of industrial productivity, 1 mol% or more is preferable, and 5 mol%. The above is more preferable, and 10 mol% or more is still more preferable.

  As the dilution gas in the raw material gas, one or two or more gases selected from a condensable gas and a non-condensable gas can be arbitrarily used as long as they do not adversely affect the dehydration reaction for generating acrolein from glycerin. The condensable gas that can be used as the diluent gas includes water vapor, which is advantageous as a diluent gas because it has advantageous effects on the life of the solid acid catalyst and the yield of acrolein. One non-condensable gas is a compound or a simple gas having a boiling point of 0 ° C. or lower under normal pressure conditions, and examples thereof include nitrogen-containing gas, carbon dioxide gas, oxygen-containing gas such as air, and rare gas such as helium. It is done. Moreover, you may use both condensable gas and non-condensable gas.

  From the acrolein gas composition obtained by the gas phase dehydration reaction of glycerin, a part or all of the diluted gas component after recovering acrolein by absorption or condensation with a solvent or the like can also be recycled as a diluent gas. Furthermore, an acrolein derivative such as acrylic acid may be produced using acrolein, and a part or all of the diluted gas component after the obtained acrolein derivative is taken out by absorption or condensation may be recycled as a dilution gas.

  When an oxidizing gas such as oxygen is included as a diluent gas, the accumulation of carbonaceous material on the solid acid catalyst may be reduced, and the effect of suppressing the decrease in the activity of the solid acid catalyst may be obtained. However, if the amount of the oxidizing gas is too large, the yield of acrolein is reduced by the combustion reaction, which is not preferable. The amount of oxygen contained in the raw material gas is 20 mol% or less (more preferably 15 mol% or less) in the raw material gas at the reactor inlet, and 3.5 times or less of the glycerin partial pressure, whichever is lower. Preferably there is.

  Regarding the type and amount of the dilution gas, a dehydration reaction product gas containing acrolein is removed after removing part or all of water, which is a component having a higher boiling point than acrolein, if necessary, and then acrolein such as acrylic acid. The production efficiency of the acrolein collecting process, the type and amount of dilution gas components, and combinations of these, such as when used for the manufacture of derivatives and when collecting acrolein produced by dehydration, etc. What is necessary is just to adjust suitably according to conditions.

  In addition, the acrolein yield may be low or unstable immediately after the start of the supply of the raw material gas into the reactor (hereinafter, the period in which the acrolein yield is low and unstable is sometimes referred to as “induction period”). ). In order to shorten the induction period, pretreatment may be performed with a gas containing an organic compound.

  The step of performing the pretreatment may be any of (I) before using an unused catalyst, (II) after performing a regeneration treatment after the dehydration reaction step, and before performing a dehydration reaction by contacting with the reaction raw material gas. Well, both are more preferred.

  The pretreatment method may be carried out outside the dehydration reactor, or may be carried out while being filled in the dehydration reactor. In the case of the unused catalyst (I), a pretreated catalyst may be charged in a dehydration reactor, or after being charged in a dehydration reactor and pretreated in the reactor, glycerin May be supplied to carry out a dehydration reaction. When the regeneration treatment step (II) is performed in a dehydration reactor, it is convenient and recommended that the regeneration step be performed in the reactor without the need for removing and refilling the catalyst. Further, by combining these, a dehydration reaction can be carried out using an unused catalyst that has been pretreated outside the dehydration reactor, and the regeneration treatment can be carried out in the reactor.

  It may be purged with an inert gas such as nitrogen after the pretreatment is finished and before the dehydration reaction is started. For example, when pretreatment is performed in a pretreatment device outside the dehydration reactor, when pretreatment is performed in the dehydration reactor with the pretreatment device and / or the dehydration reactor filled with the catalyst. In the dehydration reactor, purging with nitrogen or the like may be performed for the purpose of removing excess organic matter remaining in the system or oxygen mixed during catalyst filling.

  The organic compound other than glycerin used in the pretreatment may be a compound containing at least carbon and hydrogen as constituent elements, and is economically preferable if it is cheaper than glycerin.

  The organic compound used for the pretreatment may be a gas, a liquid, a mixed gas, or a solution, or a mixture with a non-organic compound. Examples of the non-organic compound include nitrogen, oxygen, carbon dioxide, water vapor, rare gas, and the like for gas, and water for liquid.

  The method of bringing into contact with the organic compound used in the pretreatment or a mixture with the organic compound (hereinafter sometimes collectively referred to as a treating agent) is not particularly limited, such as a continuous flow type, a batch type, a semibatch type, and the like. . If it is an unused catalyst, a pretreatment step can be performed in the final step of catalyst preparation.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

(Catalyst Preparation Example 1)
Powdered tantalum pentachloride (> 99.9%) was slowly added to 3 times the amount of 7M aqueous ammonia solution with stirring. The suspension was heated to 100 ° C. and refluxed at the same temperature for 2 hours. After 3 hours, the solid matter (precipitate) separated by suction filtration was washed. The washing was mixed with ion-exchanged water heated to 80 ° C., which is about 60 times the solid, and then stirred for 1 hour, and then the solid content was separated by suction filtration. The solid material obtained by repeating the washing operation 6 times was dried in an air atmosphere at 110 ° C. overnight, and then calcined in an air atmosphere at 350 ° C. for 5 hours. The obtained solid was crushed and classified into 0.7 to 1.4 mm to obtain catalyst 1 made of tantalate. The obtained tantalum acid was heated to 700 ° C. with a thermogravimetric analyzer (TG), and the water content was calculated from the weight reduction. As a result, it was 1.0% by mass. The BET specific surface area was 89.2 m ² / g.

The acid strength and acid amount were determined by the following procedure. The prepared catalyst was classified to 100 to 180 mesh, dried at 315 ° C. for 4 hours under a nitrogen flow, then quickly transferred to a sealed container, and placed in a desiccator to cool to room temperature. In the dry box, 100 mg of the cooled sample was transferred to a sealed container, to which 2.0 ml petroleum ether was added. An appropriate amount of a 0.1 mol / L n-butylamine solution dissolved in a petroleum ether solvent was quickly added thereto and sealed. The sample was vibrated with an ultrasonic vibrator for 30 minutes. A plurality of samples having different amounts of the added 0.1 mol / L n-butylamine solution were prepared. A few drops of 0.1 wt% Hammett indicator dissolved in a toluene solvent was dropped on this solution and allowed to stand for about a day. When the acid strength and the acid amount were determined from the coloration of the sample, −8.2 <H ₀ ≦ − The acid amount at an acid strength of 3.0 was 0.05 mmol / g, and the acid amount at an acid strength of −3.0 <H ₀ ≦ + 6.8 was 0.25 mmol / g.

(Experimental example 1)
A gas obtained by vaporizing a 36.2% by mass glycerin aqueous solution was prepared. 0.63 ml of the catalyst 1 was filled in a stainless steel reaction tube, and the reactor was placed in an electric furnace at 315 ° C. to circulate the reaction raw material gas through the reactor. The GHSV at this time is 4000 hr ⁻¹ .

  The effluent gas is cooled and collected every hour from 0 to 10 hours after the reactor inlet gas is circulated in the reactor (hereinafter, the “cooled liquefied product of the collected effluent gas” is referred to as “effluent”). The effluent was identified and quantitatively analyzed by gas chromatography (GC). As a result of the qualitative analysis by GC, by-products such as 1-hydroxyacetone, acetaldehyde, propionaldehyde and the like were detected together with glycerin and acrolein. From the quantitative analysis results, glycerol conversion, acrolein selectivity, 1-hydroxyacetone selectivity, acetaldehyde, propionaldehyde, acetic acid and allyl alcohol selectivity were calculated.

  Here, the glycerin conversion rate is a value calculated by (1− (number of moles of glycerin in the collected effluent) / (number of moles of glycerin introduced into the reactor in 60 minutes)) × 100. . Further, the acrolein selectivity is a value calculated by ((molar number of acrolein) / (molar number of glycerin introduced into the reactor in 60 minutes)) × 100 / glycerin conversion × 100. The hydroxyacetone selectivity is a value calculated by ((mole number of 1-hydroxyacetone) / (mole number of glycerin introduced into the reactor in 60 minutes)) × 100 / glycerin conversion rate × 100. Each selectivity of acetaldehyde, propionaldehyde, acetic acid, and allyl alcohol was calculated similarly.

(Comparative Experimental Example 1)
The same reaction as in Example 1 was performed except that commercially available tantalum oxide Ta ₂ O ₅ (99.9%, manufactured by Wako Pure Chemical Industries, Ltd.) was used as the catalyst. After 0.63 ml of Ta ₂ O ₅ was filled in the stainless steel reaction tube shown in Experimental Example 1, this was placed in an electric furnace at 315 ° C., and nitrogen was passed for 60 minutes, followed by reaction. Similarly, Ta ₂ O ₅ heat-treated at 315 ° C. was heated to 700 ° C. with a thermogravimetric analyzer (TG), and the water content was calculated from the weight reduction. As a result, it was 0.01% by mass. The BET specific surface area was 2.9 m ² / g.
Further, the acid strength and acid amount were determined by the same method as shown in Catalyst Preparation Example 1. The acid amount at an acid strength of −8.2 <H ₀ ≦ −3.0 is ₀ mmol / g, and the acid amount at an acid strength of −3.0 <H ₀ ≦ + 6.8 is 0.007 mmol. / G.

  The reaction results of Experimental Example 1 and Comparative Experimental Example 1 are shown in Table 1.

  It can be seen that in Comparative Example 1 using tantalum oxide containing no tantalate, both the conversion rate of glycerin and the selectivity of acrolein are significantly lower than that of Experimental Example 1.

(Catalyst preparation examples 2 to 6)
A catalyst composed of tantalum acid was prepared in the same manner as in Catalyst Preparation Example 1 except that the calcination temperature was changed. The results are shown in Table 2.

(Experimental Examples 2-6)
The same reaction as in Experimental Example 1 was performed using the catalysts 2 to 6. The results are shown in Table 3.

  According to the present invention, acrolein can be produced with high selectivity in the dehydration reaction of glycerin.

Claims (6)

A catalyst for use in a method for producing acrolein by vapor phase dehydration reaction of glycerin, wherein the catalyst is for glycerin vapor phase dehydration containing tantalum acid. The glycerin gas phase dehydration catalyst according to claim 1, wherein water contained in the tantalum acid is 0.1 mass% or more. When the acid amount distribution of the tantalum acid is measured by titration, the acid amount in a range represented by Hammett's acid strength H ₀ of −8.2 <H ₀ ≦ −3.0 is 0.001 mmol / g. It is the above, The catalyst for glycerol vapor phase dehydration of Claim 1 or 2 characterized by the above-mentioned. The catalyst for glycerin gas phase dehydration according to any one of claims 1 to 3, wherein the catalyst containing tantalum acid is obtained by calcining a hydroxide of tantalum at 50 to 600 ° C. A method for producing acrolein by dehydrating glycerin in the presence of a catalyst, wherein the catalyst is the glycerol vapor phase dehydration catalyst according to any one of claims 1 to 4. . 6. The method for producing acrolein according to claim 5, wherein at least a part of glycerin in the dehydration reaction product is recovered and used as a raw material.