JP2008174544A - Method for production of acrolein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for the production of acrolein by a gas-phase dehydration reaction using an unrefined glycerine obtained from the naturally-occurring, recyclable resources such as fat-and-fatty oil without wasting substantial energy cost nor needing many processes for refining. <P>SOLUTION: The method for producing acrolein from glycerine is characterized by separating a glycerine composition containing at least glycerine into (A) a glycerine-containing gas including at least glycerine and (B) a non-gasified component including that having at least a boiling point higher than that of glycerine, and bringing at least a part of glycerine included in the component (A) into contact with a solid acid catalyst without liquefying. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to acrolein production by gas phase dehydration reaction of glycerin using a glycerin composition.

Biodiesel produced from vegetable oil is attracting attention not only as a substitute for fossil fuels but also because it emits less carbon dioxide, and demand is expected to increase. When this biodiesel is produced, glycerin is produced as a by-product, so it is necessary to make effective use of it. One embodiment of the use of glycerin includes the use of glycerin as a raw material for acrolein.

  In the production of acrolein from glycerin by a dehydration reaction, it has long been known to use a solid acid catalyst.

  A method for producing acrolein by gas phase dehydration reaction of glycerol using a solid strong acid catalyst having an acid strength function H0 in the range of −9 to −18 is disclosed (see Patent Document 1).

  In the above patent document, glycerin, which is a raw material, is a renewable raw material that is produced in a reaction for transesterification of fats and oils, which is a method for producing biodiesel fuel, and is an environmentally friendly naturally-derived compound that is useful using the glycerin. It describes the production of the chemical acrolein.

International Publication WO2006-070884

  Glycerin made from fats and oils, which are natural raw materials, is an organic substance such as fatty acid sodium salts, fatty acid esters, alcohols, and other organic substances such as fatty acids derived from fats and oils, production processes such as transesterification, sodium hydroxide and sodium chloride. It is obtained as a crude glycerin containing an inorganic metal salt or the like. Usually, after removing an alkali metal such as sodium by neutralization, washing with water or ion exchange, it can be generally obtained as purified glycerin through a purification step such as distillation.

  In other words, in order to produce acrolein via glycerin using fats and oils that are natural raw materials, many steps are required for purification of glycerin. Furthermore, in order to produce acrolein by vapor phase dehydration reaction using the purified glycerin, it is necessary to heat and vaporize the obtained purified glycerin. There are problems such as purification by vaporization / condensation, vaporization in a gas phase dehydration reaction, and a large amount of energy required.

  On the other hand, if crude glycerin is used as a raw material for acrolein production as it is, it is not preferable because the contained alkali metal compound or high boiling point component may cause accumulation of carbonaceous substances in the reaction tube or decrease in catalyst performance. .

  That is, in order to produce acrolein by gas-phase dehydration reaction using naturally derived glycerin, it requires many steps for purification and enormous energy costs, so a more efficient and economical method is desired. .

  As a result of intensive studies on a method for producing acrolein using crude glycerin, the present inventors have purified a mixture containing glycerin by distillation, and acrolein by vapor phase dehydration reaction without liquefying the glycerin-containing gas vaporized at that time It was discovered that it can be produced more efficiently by using it as a raw material for production of the present invention, and the following invention was completed.

  (1) A glycerin composition containing at least glycerin is separated into (A) a glycerin-containing gas containing at least glycerin and (B) a non-gasification component containing a component having a boiling point higher than that of glycerin. A method for producing acrolein from glycerin, comprising producing acrolein by contacting at least a part of glycerin contained with a solid acid catalyst without liquefying.

  (2) The method for producing acrolein according to (1), wherein the ratio of glycerin contained in (A) is 80% by mass or more based on the total organic compounds contained in (A). .

  (3) The non-gasification component containing a component having a boiling point higher than that of glycerin contained in the (B) is a linear or branched fatty acid and / or fatty acid alkali metal salt or inorganic alkali metal salt having 12 or more carbon atoms. One or more components chosen from these are contained, The manufacturing method of acrolein as described in (1)-(2) characterized by the above-mentioned.

  (4) The method for producing acrolein according to (1) to (3), wherein the partial pressure of glycerin in the reaction raw material gas at the gas phase dehydration reactor inlet is 30 kPa or less.

  According to the method of the present invention, even if crude glycerin is used, it can be used as a raw material for the gas phase dehydration reaction of acrolein, so that it is economically more efficient using glycerin obtained from natural resources such as fats and oils as a raw material. Can produce acrolein.

  A method for producing acrolein by dehydration reaction of glycerin according to the present invention will be described based on an embodiment.

The present invention separates a glycerin composition containing at least glycerin into (A) a glycerin-containing gas containing at least glycerin and (B) a non-gasification component containing at least a component having a boiling point higher than that of glycerin. Is a method for producing acrolein from glycerin, wherein at least part of the glycerin contained in the product is brought into contact with a solid acid catalyst without being liquefied to produce acrolein, but other than glycerin contained in the crude glycerin used A pretreatment step according to the amount and type of the component, and a step of adjusting the reaction gas composition suitable for the gas phase dehydration reaction by adding a dilution gas or the like to the glycerin-containing gas of (A). .
Hereinafter, the manufacturing process of acrolein by vapor phase dehydration reaction will be described in reverse order.

(Α) Process for producing acrolein by gas phase dehydration reaction The process for producing acrolein by gas phase dehydration reaction in this embodiment is carried out in a reactor arbitrarily selected from a fixed bed reactor, a moving bed reactor, a fluidized bed reactor and the like. Acrolein is produced by vapor phase dehydration reaction in which a raw material gas containing glycerin is brought into contact with a catalyst.

  As the solid acid catalyst, any compound having solid acidity may be used. (A) Crystalline metallosilicate, (b) metal oxide, (c) clay mineral, (d) mineral acid is converted to α-alumina, silica, oxidation Examples include those supported on an inorganic carrier such as zirconium and titanium oxide, (e) metal salts of phosphoric acid and sulfuric acid, and those supported on an inorganic carrier such as α-alumina, silica, zirconium oxide, and titanium oxide. .

  (A) As a crystalline metallosilicate, one or more elements selected from Al, B, Fe, Ga and the like are T atoms, and the crystal structure thereof is LTA, CHA, FER, MFI, MOR, There are BEA, MTW, etc. (b) As the metal oxide, in addition to single metal oxides such as Al2O3, TiO2, ZrO2, SnO2, V2O5, SiO2-Al2O3, SiO2-TiO2, TiO2-WO3, WO3-ZrO2 (C) As clay minerals, there are bentonite, kaolin, montmorillonite, etc. (d) As mineral acid is supported on an inorganic carrier, phosphoric acid and sulfuric acid are alumina, silica, zirconia, etc. (E) Metal salts of phosphoric acid and sulfuric acid include MgSO4, Al2 (SO4) 3, K2SO4 AlPO4, YPO4, BPO4, Zr3 (PO4) 4 and the like.

  Specifically, solid acids (such as zirconium oxide carrying phosphoric acid, sulfuric acid, or tungsten oxide) disclosed in International Publication Nos. WO2006 / 087083 and WO2006 / 087084 can also be used.

  Preferably, solid acids having a medium or higher acid strength known to those skilled in the art (for example, Chemical Review No. 34 P78-89 (1982) Kobe Tabe et al., Tables 1 and 2 described in Tables 1 and 2). The function H0 is a solid acid having an acidity of +1.5 or less.

  Among these, since they are exposed to an oxidizing or reducing atmosphere at a high temperature during dehydration or regeneration, a solid catalyst having good stability is preferable, and crystalline metallosilicates, metal oxides, clay minerals, and the like are preferable. As the crystalline metallosilicate, ZSM5 having an MFI structure with T atom as Al is particularly suitable, and as the metal oxide, crystalline aluminum phosphate is particularly suitable.

  In this reaction, the catalyst with reduced activity can be regenerated by bringing it into contact with a gas containing an oxidizing gas such as oxygen at a high temperature. The form of contact is not particularly limited, and the catalyst may be removed from the reactor, or may be switched by switching the gas to be circulated in the same reactor as the dehydration reaction. When the dehydration reaction is carried out in a fixed bed, the latter method, which does not require the trouble of extracting and refilling the catalyst, is simpler and recommended.

  When oxygen is used as the oxidizing gas used for regeneration, it is inexpensive to use oxygen in the air, but an inert gas such as nitrogen, carbon dioxide, or water vapor may be accompanied. In particular, it is recommended to use an inert gas in order to adjust the oxygen concentration when there is a concern about sudden heat generation because the air contains about 20% by volume of oxygen. Before and after the regeneration treatment, purging with an inert gas such as nitrogen may be performed for the purpose of removing or reducing excess organic matter remaining in the system and residual oxygen after the regeneration treatment.

  The regenerated catalyst can be used again as a catalyst for acrolein synthesis by contacting with the reaction raw material gas.

  The glycerin partial pressure in the reaction raw material gas at the reactor inlet is preferably 30 kPa or less, preferably 25 kPa or less, more preferably 20 kPa or less, and even more preferably 15 kPa or less. The glycerin partial pressure is preferably low, but in order to ensure a certain productivity, methods such as (I) lowering the reaction pressure and (II) entraining a large amount of diluted components are required. From an industrial point of view, (I) requires a highly airtight and high pressure resistant reactor and a large pressure reducing device, and (II) collects the generated acrolein and costs and pressure loss of a large amount of diluted components. From the industrial viewpoint, 0.01 kPa or more is preferable, 0.1 kPa or more is more preferable, and 1 kPa or more is even more preferable.

  The glycerin partial pressure refers to the partial pressure of glycerin gas in the reaction raw material gas at the reactor inlet. For example, if the glycerin gas volume ratio (vol%) in the reaction raw material gas is 100 vol%, the glycerin partial pressure is the pressure of the raw material gas at the inlet of the reactor, and if a gas component other than glycerin is included, the reaction It is a value corresponding to the glycerin gas volume ratio (vol%) in the reaction raw material gas out of the total pressure of the raw material gas at the inlet of the vessel.

  The total pressure of the reaction raw material gas at the reactor inlet may be 0.01 kPa or more, more preferably 0.1 kPa or more, and further preferably 1 kPa or more. The upper limit of the pressure is not limited as long as the reaction raw material gas at the inlet of the reactor can exist as a gas, but is usually 500 kPa or less, more preferably 300 kPa or less, and still more preferably 200 kPa or less. When separating a glycerin composition to be described later into (A) and (B), when using a separation method utilizing a boiling point difference such as distillation, the boiling point of glycerin is as high as 290 ° C. In the case of carrying out the process, the dehydration reaction step is also preferably carried out under reduced pressure conditions.

  Since the preferred partial pressure of glycerin is 30 kPa or less, if the pressure of the reaction raw material gas at the reactor inlet is 30 kPa or higher, a diluting component other than glycerin is always included in the raw material gas. Moreover, even if the pressure of the reaction raw material gas at the reactor inlet is 30 kPa or less, a dilution component may be contained.

  Examples of the diluting component include water vapor, nitrogen gas, and air. Particularly, when water vapor is added, advantageous effects are seen with respect to the life of the catalyst and the yield of acrolein. Further, from the acrolein composition obtained by the vapor phase dehydration reaction of glycerin, a part of the diluted components after the acrolein is taken out by absorbing or condensing the acrolein with a solvent or the like can be recycled. Further, acrolein derivatives such as acrylic acid can be synthesized using the obtained acrolein, and a part of the diluted component after the obtained acrolein derivative is taken out by absorption or condensation can be recycled as a diluted component of the dehydration reaction. I do not care.

  When water vapor is used as a diluting component, the water vapor may be accompanied by glycerin from the purification step, may be newly added, or both may be mixed. A preferable amount of water vapor is such that the partial pressure of water is 5 times or less of the glycerin partial pressure in the raw material gas at the inlet of the dehydration reactor. More preferably 3 times or less, and even more preferably 2 times or less, a suitable effect on catalyst life and yield can be obtained, and a large burden is imposed on the purification process of the dehydration reaction product. It does not take, and is suitable.

  When the dehydration reaction is carried out at normal pressure or under pressure, a non-condensable and non-oxidizing gas that does not liquefy at normal temperature and normal pressure, such as nitrogen, can be used as a diluent component other than water vapor. However, when collecting acrolein produced by the dehydration reaction, it is necessary to consider the collection efficiency in the acrolein collection step, usually 20 times or less of the glycerin partial pressure, more preferably 15 times or less, More preferably, it is 12 times or less.

  The space velocity of the reaction raw material gas at the reactor inlet including the total amount of glycerin and dilution gas (hereinafter sometimes referred to as reaction gas GHSV) is usually 70 to 50000 hr-1, preferably 70 to 25000 hr-1. More preferably, it is 100-12000hr-1, More preferably, it is 125-12000hr-1.

  The gas phase dehydration reaction temperature is preferably 250 to 500 ° C, more preferably 300 to 450 ° C, and still more preferably 330 to 440 ° 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.

  In addition to the diluting component, when a small amount of an organic compound other than glycerin is contained in the reaction raw material gas, the yield of acrolein immediately after the start of the reaction is low. . Preferred organic compounds include acrolein, acetaldehyde, acetic acid, acrylic acid, methanol, ethanol, fatty acid, fatty acid ester and the like.

  The amount of the organic compound is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total organic compound contained in the reaction raw material gas, because the amount of the organic compound may accelerate the decrease in catalytic activity. More preferably, it is 5 mass% or less.

  Further, when the dehydration reaction is carried out at normal pressure or under pressure, an oxidizing gas such as oxygen can be included in the diluted component as a diluted component other than water vapor. If an oxidizing gas is contained, the accumulation of carbonaceous material on the catalyst may be reduced, and an effect of suppressing a decrease in the activity of the 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. A preferable range when oxygen is used as the oxidizing gas is any of oxygen partial pressure ratio of 15% or less and / or oxygen partial pressure of 3.5 times or less of glycerin partial pressure in the reaction raw material gas at the reactor inlet. It is preferable that it is below a low value.

  When the dehydration reaction is carried out using the dilute component under reduced pressure conditions, it is preferable to use water vapor or the like that condenses at room temperature and normal pressure at a lower boiling point than glycerin in order to suppress the load on the reduced pressure apparatus.

  As a diluting component other than the glycerin, a target product such as acrolein or an acrolein derivative is obtained from a reaction product gas containing acrolein generated by the reaction or a reaction product gas of an acrolein derivative (for example, acrylic acid) using the acrolein as a raw material. Some or all of the remaining components removed may be used.

(Β) Separation step of separating the glycerin composition into (A) a glycerin-containing gas and (B) a non-gasification component In this step, (A) a glycerin-containing gas containing at least glycerin from the glycerin composition, and (B) A separation process that separates into at least a non-gasification component containing a component having a higher boiling point than glycerin may be used, and a known method can be used. For example, a method of vaporizing glycerin by heating such as distillation or evaporation is simple and suitable. Yes.

  In the method of vaporizing glycerin by heating such as distillation, since the boiling point of glycerin is as high as 290 ° C., if impurities contained in the glycerin composition have undesirable effects on the operation due to polymerization, alteration, etc., the decompression condition Can be implemented below.

  In (A), as described in the dehydration reaction conditions, the glycerin content in the total organic compound contained may be 80% by mass or more, and the remainder may contain an organic compound other than glycerin. . However, when an alkali metal compound is contained in (A), the solid acid catalyst may be irreversibly deactivated. Therefore, it is preferable that the separation method does not contain at least an alkali metal compound.

  The component (B) contains at least a component having a boiling point higher than that of glycerin, and particularly preferably contains all alkali metals in the glycerin mixture. In addition, it is preferable that (B) does not contain glycerin. However, in order to adjust the composition of (A) (for example, adjustment of the amount of high-boiling compounds contained and alkali metal compounds are not included). Glycerin may be included in order to simplify the operation of discharging (B) due to a decrease in viscosity or the like by adding a small amount of glycerin. When an alkali metal compound is contained in the glycerin composition, a method of removing the metal salt and the like at the same time as vaporizing glycerin using a forced stirring type thin film dropping evaporator can be used.

  In addition, glycerin vaporized by blowing a gas such as nitrogen or air into the glycerin composition heated using an evaporator is extracted from the upper part, and components having higher boiling points than glycerin, such as fats and oils, glycerin are produced from the lower part. It can also be carried out by extracting an alkali metal compound used or generated in the process.

  In order to obtain a glycerin raw material gas suitable for the gas phase dehydration reaction, it is preferable to perform a step of preparing a composition containing glycerin according to the amount and type of components other than glycerin contained in the raw material glycerin composition to be used.

  For example, in order to prevent the glycerin content in the total organic compound contained in the above (A) from being 80% by mass or less, an organic compound having a boiling point lower than that of glycerin contained in the raw glycerin composition is known, such as distillation or evaporation. It is preferable to adjust the amount by removing it until an appropriate amount is obtained by this technique.

  In addition, since a large amount of water is contained in the raw material glycerin composition, in order to prevent the amount of water vapor in the reaction raw material gas from becoming larger than the mass of glycerin in the reaction raw material gas, known methods such as distillation and evaporation It is preferable to adjust the water content, for example, by removing until an appropriate amount is obtained by this technique.

  The raw material glycerin composition used in the present invention is preferably a glycerin composition containing glycerin derived from natural resources produced by transesterification of fats and oils or a soap manufacturing process. There may be a large amount of alkali metal salts such as sodium and alkali metal hydroxides such as sodium hydroxide. If the alkali metal compound is contained in a large amount, the operation in the separation process is hindered or there is an influence such as corrosion of the apparatus. It is preferable to adjust the content and the like by pretreatment.

  The (A) glycerin-containing gas obtained in the separation step can be used for a gas phase dehydration reaction without liquefying the entire amount of glycerin contained, but the purpose and gas for adjusting the partial pressure of glycerin in the reaction raw material gas can be used. A part of glycerin may be liquefied in order to adjust the amount of glycerin supplied to the phase dehydration reaction.

  As an embodiment of the present invention, a part of an existing glycerin production apparatus is improved and a gas containing glycerin obtained from a glycerin distillation process is sent to the acrolein production process as the (A) glycerin-containing gas. Also good. The glycerin production apparatus in the present invention is an apparatus for producing soap using fats and oils, caustic soda, etc., an apparatus for producing methyl esters of fatty acids by transesterification of fats and oils, etc. Also included is a device to perform.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the scope of the present invention is not limited only to these Examples. The glycerin conversion rate, acrolein yield, and SV (space velocity) are values calculated by the following formula.
Glycerin conversion rate = (1− (number of moles of glycerin in the collected effluent) / (number of moles of glycerin introduced into the reactor in 30 minutes)) × 100
Yield of acrolein = ((number of moles of acrolein in the collected effluent) / (number of moles of glycerin introduced into the reactor in 30 minutes)) × 100
SV (space velocity) = (gas supply amount converted under standard conditions, L / hr) / (catalyst amount, L)
(Catalyst Preparation Example 1)
By executing the following supporting process, crystallization process, and ion exchange process, H-type MFI catalysts (methanosilicate molded bodies in which T atoms are Al) of each Example and Comparative Example were produced.

(Supporting process)
1.40 g of NaOH and 0.47 g of NaAlO 2 were sequentially dissolved in 15.00 g of distilled water, and 10.15 g of 40 mass% tetra-n-propinoleammonium hydroxide aqueous solution was added to the distilled water. Then, distilled water was added to this solution to prepare an impregnating solution having a total amount of 30 ml.

  Next, silica beads (“CARTIACT Q50” manufactured by Fuji Silysia Chemical Co., Ltd., 10 to 20 mesh, average pore diameter of 50 nm) are used for the silica compact, and 30 g of silica beads dried at 120 ° C. for 1 day is used as the impregnation liquid. Impregnation for 1 hour. Thereafter, the silica beads were dried on an evaporating dish placed on a 100 ° C. hot water bath, and further dried at 80 ° C. under a nitrogen stream for 7 hours to obtain Na and Al crystallizing agents necessary for crystallization. A crystalline methanosilicate precursor was obtained by supporting it on beads.

(Crystallization process)
The precursor obtained in the supporting step is placed in the hollow part of a tetrafluoroethylene jacketed crucible having a volume of 100 ml, and 1.00 g of distilled water is placed at the bottom of the crucible, and this crucible is placed in an electric furnace at 180 ° C. for 8 hours. Left to stand.

(Ion exchange process)
The solid after the crystallization process was immersed in 300 g of a 1 mol / L ammonium nitrate aqueous solution at 60 ° C. and stirred for 1 hour, and then the supernatant was discarded. This operation was repeated several times. Thereafter, the solid was washed with water.

(Baking process)
The solid after the ion exchange step was baked at 540 ° C. for 3.5 hours in an air stream. By this calcination, catalyst A which is H-type MFI was obtained.
(Catalyst preparation example 2)
To a solution of 160 g of aluminum nitrate nonahydrate and 800 g of ion-exchanged water, 49 g of 85% by mass orthophosphoric acid was mixed. To this mixed solution, 96.7 g of 28% by mass aqueous ammonia was added dropwise over about 50 minutes (a white precipitate was formed from the beginning of the addition), and the mixed solution was stirred for 1 hour. Next, the solid (precipitate) separated from the mixed solution by suction filtration was washed. For washing, a solid and 800 g of ion-exchanged water were mixed, stirred for 1 hour, and then allowed to stand for 1 hour, after which the solid content was separated by suction filtration. The solid obtained by repeating the washing operation three times was dried overnight at 120 ° C. in an air atmosphere, and then fired at 1200 ° C. for 3 hours in an air atmosphere. The obtained solid was crushed and classified to 0.7 to 1.4 mm to obtain Catalyst B.

(Example 1)
A glycerin composition M consisting of 80% by mass glycerin, 10% by mass water, 3% by mass methanol, 2% by mass stearic acid, 5% by mass sodium chloride at a flow rate of 10 g / hr and nitrogen at 100 ml / min The reaction raw material gas consisting of 20.1 vol% glycerin, 15 vol% water, 2.4 vol% methanol, and 62.5 vol% nitrogen was prepared.

15 ml of catalyst A was filled in a stainless steel reaction tube (inner diameter 10 mm, length 500 mm), this reactor was immersed in a molten salt bath at 360 ° C., and the reaction raw material gas was circulated through the reactor. The pressure of the reaction raw material gas at the reactor inlet was 104.3 kPa.
After flowing the reactor inlet gas through the reactor, the effluent gas was cooled and collected for 0.5 to 1 hour and 6.5 to 7.0 hours for 30 minutes, and the effluent was discharged by gas chromatography (GC). Qualitative and quantitative analysis of the product was performed. As a result of qualitative analysis by GC, by-products such as 1-hydroxyacetone were detected together with glycerin and acrolein. Further, the conversion rate, acrolein yield, and acrolein yield were calculated from the quantitative analysis results.

  The obtained reaction results are shown in Table 1.

(Example 2)
The same operation was performed except that the catalyst A was changed to the catalyst B in Example 1. The reaction results are shown in Table 1.

(Example 3)
In Example 1, the same operation was carried out except that nitrogen was not supplied, a pressure reduction device was connected to the reactor outlet side, and the reaction was performed while controlling the pressure of the reaction raw material gas at the reactor inlet to 37 kPa. It was. The reaction results are shown in Table 1.

(Comparative Example 1)
In Example 1, the same operation was performed except that the glycerin composition M and nitrogen were directly introduced into the reactor without passing through the evaporator, but the reaction continued with the pressure at the reactor inlet rising. The reaction was stopped after 5 hours because it became difficult to do. When the extracted reaction tube was opened and the reaction gas inlet portion of the catalyst layer was inspected, a white solid was accumulated together with the black carbonaceous material and was blocked.

(Comparative Example 2)
Instead of the glycerin mixture M in Comparative Example 1, a glycerin composition N comprising 80% by mass of glycerin, 14% by mass of water, 3% by mass of methanol, 2% by mass of stearic acid, and 1% by mass of sodium chloride is used. The same operation was performed except that. No pressure increase was observed during the reaction, and the reaction could be continued for 7 hours. The reaction results are shown in Table 1.

(Reference Example 1)
In Example 1, instead of the glycerin composition M, a glycerin mixture L composed of 80% by mass of glycerin, 17% by mass of water and 3% by mass of methanol was passed through an evaporator at 10 g / hr and nitrogen at 100 ml / min. The same operation was performed except that it was introduced directly into the reactor. The reaction results are shown in Table 1.

(Reference Example 2)
In Example 1, the same operation was carried out except that commercially available purified glycerin was introduced at 8 g / hr, ion-exchanged water at 2 g / hr, and nitrogen was introduced directly into the reactor without passing through the evaporator at a flow rate of 100 ml / min. Went. The reaction results are shown in Table 1.

  When a glycerin mixture M containing a high-boiling component such as sodium chloride or stearic acid is supplied directly to the reactor, the reaction is stopped due to blockage in the reaction tube as shown in Comparative Example 1 in Table 1, or the catalyst as shown in Comparative Example 2 Although adverse effects such as a decrease in activity are caused, in Examples 1 to 3 using the method of the present invention, the reaction can be continued without any problem. Moreover, the catalyst performance when using the present invention is equivalent to the performance obtained when the glycerin composition L from which the high-boiling components are removed as shown in Reference Example 1 or when the purified glycerin shown in Reference Example 2 is used. It can be seen that

  Even if acrolein is produced by dehydration reaction of glycerin using a glycerin mixture containing components having a higher boiling point than glycerin that affects catalyst performance such as sodium chloride, the same performance as when purified glycerin is used is obtained. Therefore, unpurified glycerin can be used as the raw material glycerin, and acrolein can be obtained economically and efficiently.

Claims (4)

The glycerin composition containing at least glycerin is separated into (A) a glycerin-containing gas containing at least glycerin and (B) a non-gasification component containing at least a component having a higher boiling point than glycerin, and the glycerin contained in (A) A process for producing acrolein from glycerin, wherein acrolein is produced by contacting at least a part of the product with a solid acid catalyst without liquefaction. The ratio of glycerol contained in said (A) is 80 mass% or more with respect to all the organic compounds contained in said (A), The manufacturing method of the acrolein of Claim 1 characterized by the above-mentioned. The non-gasification component containing a component having a boiling point higher than that of glycerin contained in (B) is selected from linear and branched fatty acids having 12 or more carbon atoms and / or fatty acid alkali metal salts and inorganic alkali metal salts. The method for producing acrolein according to claim 1, comprising one or more components. The method for producing acrolein according to claim 1, wherein the partial pressure of glycerin in the reaction raw material gas at the gas phase dehydration reactor inlet is 30 kPa or less.