WO2015012392A1

WO2015012392A1 - Catalyst for manufacturing acrylic acid and/or acrylate from lactic acid and/or derivative thereof, and method for manufacturing acrylic acid and/or acrylate

Info

Publication number: WO2015012392A1
Application number: PCT/JP2014/069712
Authority: WO
Inventors: 真則野々口; 晃士新宮原; 夕希子斎藤
Original assignee: 株式会社日本触媒
Priority date: 2013-07-25
Filing date: 2014-07-25
Publication date: 2015-01-29
Also published as: JP2016169162A

Abstract

　This catalyst is for manufacturing acrylic acid and/or an acrylate from lactic acid and/or a derivative thereof by dehydration, wherein the catalyst contains a phosphate compound including both an alkali metal and an alkaline-earth metal. This method for manufacturing acrylic acid and/or an acrylate has a step for obtaining the acrylic acid and/or acrylate from lactic acid and/or a derivative thereof by dehydration using this catalyst.

Description

Catalyst for producing acrylic acid and / or acrylic ester from lactic acid and / or its derivative, and method for producing acrylic acid and / or acrylic ester

The present invention relates to a catalyst for producing acrylic acid and / or an acrylic ester, and a method for producing acrylic acid and / or an acrylic ester. Specifically, a catalyst for producing acrylic acid and / or an acrylate ester by using lactic acid and / or a derivative thereof as a raw material and subjecting it to a dehydration reaction, and acrylic acid and / or an acrylate ester using the catalyst It relates to the manufacturing method.

A polyacrylic acid (salt) water-absorbing resin using acrylic acid and / or a salt thereof as a monomer has high water absorption performance, so that it can absorb absorbent articles such as paper diapers and sanitary napkins, and a water retention agent for agriculture and horticulture. Industrial water-stopping materials are often used industrially.

The current method for producing acrylic acid is generally a method in which propylene is oxidized in air, but this method is produced by converting propylene to acrolein by catalytic gas phase oxidation and converting it to acrylic acid in catalytic gas phase oxidation. Has been. However, the production method uses propylene obtained by refining crude oil, which is a fossil resource, as a raw material, and a production method that can reduce raw material costs and environmental burden in view of problems such as recent rise in crude oil prices and global warming. An alternative to is desired.

As a production method that can replace such a current production method, a synthesis method from a carbon-neutral biomass raw material has been actively researched. Research on methods for obtaining acid esters is ongoing. This method is generally a method of obtaining acrylic acid or acrylic acid ester by intramolecular dehydration reaction such as lactic acid or lactic acid ester on a solid catalyst such as zeolite under a high temperature condition of 300 ° C. or more (Non-patent Documents 1, 2, Patent Document 1).

International Publication No. 2011/052178

In the dehydration reaction of lactic acid or lactic acid ester described in the prior art document, it cannot be said that the conversion rate of raw lactic acid or lactic acid ester and the selectivity of acrylic acid or acrylate ester are still sufficient. Although prior art documents have been improved by adding an alkali metal to the catalyst by means such as loading or ion exchange for the purpose of improving selectivity, it is scattered in the reaction gas due to its weak bond with the catalyst component. As a result, the composition and structure of the catalyst itself may change, and the activity and selectivity of the catalyst may rapidly decrease. In addition, when an inorganic binder such as silica sol or alumina sol, which is commonly used as a catalyst molding aid, is present in the catalyst, the added alkali metal escapes from the catalyst active point and moves onto the binder component, causing coking. May cause undesirable side reactions such as In addition, as a result of a supplementary examination of the prior art documents, the catalytic active sites were covered or the catalyst pores were clogged by carbon components produced during the reaction, and some of the constituent elements of the catalyst were contained in the reaction gas together with the reaction substrate. It has been found that the activity and selectivity of the catalyst rapidly decrease in a few hours due to changes in the composition and structure of the catalyst itself by scattering.

The present invention has been made in view of the above circumstances, and an object thereof is a catalyst capable of producing acrylic acid and / or an acrylate ester with high selectivity using lactic acid and / or a derivative thereof as a raw material, and the catalyst. Another object of the present invention is to provide a method for producing acrylic acid and / or acrylic ester using

In view of the above-mentioned problems, the present inventors conducted extensive research and found that by using a catalyst containing a phosphate compound containing both alkali metal and alkaline earth metal elements as one of the catalyst components, lactic acid It has been found that acrylic acid and / or acrylic ester can be produced with high selectivity from and / or derivatives thereof. That is, the catalyst of the present invention is a catalyst for producing acrylic acid and / or an acrylate ester from lactic acid and / or a derivative thereof by dehydration reaction, and contains both elements of alkali metal and alkaline earth metal. It is characterized by containing a phosphate compound. The present invention also provides a method for producing acrylic acid and / or acrylate ester, which comprises a step of obtaining acrylic acid and / or acrylate ester from lactic acid and / or a derivative thereof by dehydration reaction using the catalyst of the present invention. .

According to the present invention, acrylic acid and / or acrylate ester is highly selected from lactic acid and / or its derivatives by using a catalyst containing a phosphate compound containing both alkali metal and alkaline earth metal elements. It can be manufactured with sex. That is, when the catalyst of the present invention is used, the alkali metal, the alkaline earth metal, and phosphoric acid in the phosphate compound contained in the catalyst are present in an ion pair and are strongly bonded to each other. It is possible to exist stably in the inside. Thereby, it is possible to prevent the alkali metal element from being scattered in the reaction gas and to prevent the structural change of the catalyst. Therefore, acrylic acid and / or acrylic ester can be produced with high selectivity.

2 is an XRD chart of the catalyst obtained in Catalyst Preparation Example 1. FIG. It is an enlarged view of FIG. FIG. 4 is an XRD chart of the catalyst obtained in Catalyst Preparation Example 2. It is a figure of the XRD chart of the catalyst obtained in the catalyst preparation example 3. FIG. FIG. 5 is an enlarged view of FIG. 4. It is a figure showing the change of the conversion rate of a lactic acid with respect to the reaction time (TOS) of Example 2, and the selectivity of a production | generation component.

〔catalyst〕
The catalyst of the present invention is a catalyst for producing acrylic acid and / or an acrylate ester by dehydration reaction from lactic acid and / or a derivative thereof, and a phosphate containing both alkali metal and alkaline earth metal elements It contains a compound. The catalyst of the present invention contains a phosphate compound containing both alkali metal and alkaline earth metal elements as one of the catalyst components.

Examples of the alkali metal include Li, Na, K, Rb, and Cs. Among them, Na is preferable because it improves the selectivity of acrylic acid. These alkali metals may be used alone or in combination of two or more.

Examples of the alkaline earth metal include Be, Mg, Ca, Sr, and Ba, and Mg, Ca, and Sr are preferably used. Of these, Ca is preferable in terms of improving the selectivity and stability of the catalyst. These alkaline earth metals may be used alone or in combination of two or more.

Examples of the phosphate include orthophosphate, pyrophosphate, and metaphosphate. Among them, orthophosphate and pyrophosphate are preferable in that both alkali metal and alkaline earth metal are stabilized at the same time, and orthophosphate is particularly preferable. These phosphates may be used alone or in combination of two or more.

Among the phosphate compounds containing both alkali metal and alkaline earth metal elements, compounds represented by the general formulas: AXPO ₄ and ABXP ₂ O ₇ are preferable. In the formula, A and B represent alkali metal elements, and X represents an alkaline earth metal. A and B may be the same element or a combination of different elements. The phosphate compound containing both alkali metal and alkaline earth metal elements may contain one or more of these compounds. Among the compounds represented by the general formula, NaCaPO ₄ and Na ₂ CaP ₂ O ₇ are preferable, and NaCaPO ₄ is particularly preferable. The compound represented by the general formula can be identified by an X-ray diffraction method (XRD method) or a nuclear magnetic resonance method (NMR method). In the case of the XRD method, the compound can be identified by comparing the X-ray diffraction peaks of the measurement species and the standard substance. In the case of the NMR method, the type of phosphate is identified by measuring the NMR of the 31P nuclide. Is possible.

The method for synthesizing the phosphate compound containing both the alkali metal and alkaline earth metal elements is not particularly limited, and a general method for synthesizing the phosphate compound may be used. For example, a precipitation method in which a phosphorus source, an alkali metal source and / or an alkaline earth metal source are mixed in the form of an aqueous solution to precipitate a precipitate, or a carbonate or oxidation of an alkali metal source and / or an alkaline earth metal source It can synthesize | combine with the solid-phase method etc. which mix and bake a thing etc. in a solid state.

As a method for synthesizing a phosphate compound, an alkaline earth phosphate is synthesized first, an alkaline metal salt aqueous solution is added to an alkaline earth phosphate solid, impregnated, and then fired. A method in which a part or all of alkaline earth phosphate is changed to a phosphate compound containing both the alkali metal and alkaline earth metal elements, and one alkaline earth metal of alkaline earth phosphate. A method of obtaining a phosphate compound containing both elements of the alkali metal and the alkaline earth metal by subjecting part or all to an ion exchange reaction with the alkali metal is also a preferable synthesis method. In this case, the ratio of changing to an alkali metal can be appropriately adjusted by changing the amount and concentration of the aqueous solution of the alkali metal salt to be added. As the alkaline earth phosphate, a compound having an apatite structure can also be suitably used.

As the alkali metal source, alkali metal nitrates, phosphates, sulfates, carbonates, chlorides, oxides, and the like can be used.

As the alkaline earth metal source, alkaline earth metal nitrates, phosphates, sulfates, carbonates, chlorides, oxides, and the like can be used.

As the phosphorus source, phosphoric acid, pyrophosphoric acid, or a sodium salt or ammonium salt thereof, or an oxide such as diphosphorus pentoxide can be used.

In the present invention, the phosphate compound containing both the alkali metal and alkaline earth metal elements may be used alone as a catalyst for dehydration of lactic acid and / or its derivatives. Or you may use together with the other catalyst component which has the dehydrating ability of the derivative (s), for example, a sulfate, nitrate, a zeolite compound, a phosphate, an apatite compound, etc.

Examples of the sulfate include Na ₂ SO ₄ , K ₂ SO ₄ , CaSO ₄ , and Al ₂ (SO ₄ ) ₃ .

Examples of the nitrate include NaNO ₃ , KNO ₃ , and Ca (NO ₃ ) ₂ .

The zeolite compound refers to a crystalline hydrous aluminosilicate having a network structure in which SiO ₄ and AlO ₄ tetrahedra share apex oxygen in the structure and are connected infinitely in three dimensions. The crystal structure of zeolite is given by the International Zeolite Society as a structure code consisting of three alphabetic capital letters. Zeolite compounds preferably used in the present invention include those represented by LTA, FER, MWW, MFI, MOR, LTL, FAU, BEA, MEL, TON, MTW and the like as structure codes. The names of the zeolite compounds include A type zeolite, ferrierite, MCM-22, ZSM-5, mordenite, L type zeolite, Y type zeolite, X type zeolite, beta zeolite, ZSM-11, theta 1, what is called ZSM-12. A so-called metallosilicate in which other metal atoms are introduced into the crystal lattice instead of Al atoms of the AlO ₄ tetrahedron is also one of the preferable zeolite compounds. In the case of a zeolite compound, an ion-type proton present on the zeolite and ion-exchanged with a cationic metal ion such as an alkali metal or alkaline earth metal is also preferably used.

Examples of the phosphate include Na ₃ PO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ , K ₃ PO ₄ , K ₂ HPO ₄ , KH ₂ PO ₄ , CaHPO ₄ , Ca ₃ (PO ₄ ) ₂ , AlPO ₄ , Examples thereof include CaH ₂ P ₂ O ₇ and Ca ₂ P ₂ O ₇ .

The apatite compound is a compound represented by the general formula X _a (MO _b ) _c Z ₂ , where X is Ca, Sr, Pb, Mg, Cd, Fe, Co, Ni, Cu, Zn, La, H, etc. 1 type or 2 types or more of these may be sufficient. As X, Ca and Sr are preferable, and Ca is particularly preferable. M represents P, V, As, C, S or the like, and among them, P is preferable. Z represents OH (hydroxyl group), F, or Cl, and OH is particularly preferable. O represents an oxygen atom. In the case of a basic apatite compound, a = 10, b = 4, c = 6, and the ratio of X atom to M atom (a / c) is 1.67, but in the case of a solid solution or the like, a / c The value of may not be 1.67.

Examples of basic apatite compounds include Mg ₁₀ (PO ₄ ) ₆ (OH) ₂ , Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , Sr ₁₀ (PO ₄ ) ₆ (OH) _2, etc. Of these, Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ is preferred.

The phosphate compound containing both alkali metal and alkaline earth metal elements is used in combination with other catalyst components capable of dehydrating lactic acid and / or its derivatives to carry out the reaction of lactic acid and / or its derivatives. In this case, the catalyst containing the phosphate compound and the catalyst containing the other catalyst component are mixed and filled in the reactor, or the respective catalysts are stacked and used, so that the effect of the combined use of the catalyst can be obtained. Obtainable.

Alternatively, the catalyst of the present invention contains other catalyst components capable of dehydrating lactic acid and / or its derivatives in addition to the phosphate compound containing both the alkali metal and alkaline earth metal elements. May be. In this case, for example, the catalyst of the present invention can be obtained by mixing and calcining the phosphate compound containing both the alkali metal and alkaline earth metal elements and the other catalyst component to be used in combination. it can. Here, the two components to be mixed may be a solid mixture, a solid mixture and a liquid mixture, or a liquid mixture.

The catalyst of the present invention may be one in which a phosphate compound containing both the alkali metal and alkaline earth metal elements is supported on a carrier. Examples of the carrier include silica, diatomaceous earth, alumina, silica alumina, silica magnesia, zirconia, titania, magnesia, niobia, ceria, zeolite, apatite compound, silicon carbide, activated carbon, etc. You may carry | support to a support | carrier and you may carry | support to the support | carrier which consists of 2 or more types of composite_body | complexes or a mixture. It is also one of preferred forms to use as a carrier the compounds mentioned as other catalyst components capable of dehydrating lactic acid and / or derivatives thereof.

The shape of the catalyst is not particularly limited, such as a spherical shape, a ring shape, a cylindrical shape, a tablet shape, a honeycomb shape, or a pulverized product thereof. You can choose.

In the catalyst of the present invention, the proportion of the phosphate compound containing both alkali metal and alkaline earth metal elements in the entire catalyst is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, 1 mass% or more is more preferable, 99.9 mass% or less is preferable, 95 mass% or less is more preferable, and 90 mass% or less is further more preferable. Here, the entire catalyst means a component constituting the catalyst, that is, a phosphate compound containing both elements of the alkali metal and alkaline earth metal constituting the catalyst, and lactic acid and / or a derivative thereof other than that. When other catalyst components having dehydrating ability, a carrier, an inorganic binder, and the like are included, it means a sum of these components.

The size of the catalyst is appropriately determined in consideration of the size and shape of the reactor, pressure loss, etc., but is usually 1 mm or more. The upper limit of the size of the catalyst is not particularly limited, and is appropriately determined in consideration of the size and shape of the reactor, the catalyst effectiveness factor, and the like. The size of the catalyst is usually 50 mm or less, preferably 30 mm or less, more preferably 10 mm or less.

According to the present invention, since the phosphate compound containing both alkali metal and alkaline earth metal elements is used as the catalyst, the alkali metal, alkaline earth metal and phosphorus in the phosphate compound contained in the catalyst are used. The acid is present as an ion pair and is firmly bonded, and the alkali metal can be stably present in the catalyst. In particular, the presence of the alkaline earth metal allows the alkali metal to be firmly fixed in the phosphate as compared with the case where the alkali metal phosphate is used. Therefore, it is possible to suppress the alkali metal element that particularly contributes to the dehydration reaction of lactic acid and / or lactic acid ester from being scattered in the reaction gas, and to prevent the structural change of the catalyst. Therefore, the catalyst activity and selectivity can be prevented from being lowered, and acrylic acid and / or an acrylate ester can be produced with high selectivity from lactic acid and / or a derivative thereof.

In addition, according to the catalyst of the present invention, it is possible to prevent an undesirable side reaction such as coking as a result of preventing the structural change of the catalyst. For example, in a catalytic reaction, when the catalyst active sites are covered or the catalyst pores are clogged by carbon generated as a by-product during the reaction, a catalyst regeneration process called aeration is performed to burn and remove the carbon after the reaction. In some cases, the catalyst performance can be recovered. However, for example, in the catalyst described in the prior art document, the activity is reduced in a short time of several hours. Therefore, it is necessary to frequently perform the catalyst regeneration treatment, which leads to a decrease in productivity. When a fluidized bed reactor is used, it is possible to perform part of the catalyst regeneration process while dehydrating the lactic acid and / or its derivatives, but the equipment becomes complicated and expensive, resulting in an increase in equipment costs. Connected. In addition, if a part of the catalyst constituent element is scattered in the reaction gas together with the reaction substrate and the composition or structure of the catalyst itself is changed, the structure of the catalyst is essentially changed due to the lack of the element. It is also assumed that the performance of the catalyst cannot be recovered due to this. However, according to the catalyst of the present invention, catalyst constituent elements can be prevented from being scattered in the reaction gas, and undesirable side reactions such as coking can be suppressed, so that the activity and selectivity of the catalyst can be maintained for a long time. Thus, acrylic acid and / or an acrylate ester can be produced from lactic acid and / or its derivatives stably for a long time with high productivity.

Furthermore, when a phosphate compound is used as a molding catalyst, there is an advantage that collapse and pulverization hardly occur. When an inorganic binder such as silica sol or alumina sol is used as a catalyst molding aid, for example, when an alkali metal is added from the outside, the added alkali metal escapes from the catalytic activity point and reacts with the inorganic binder, so that the molded catalyst becomes It tends to collapse. However, in the catalyst of the present invention, since the alkali metal is firmly bonded in the phosphate compound, it is difficult for the alkali metal to transfer from the phosphate compound to the inorganic binder, and the molded catalyst is not collapsed or pulverized. It can be suppressed. As a result, it is possible to prevent an increase in pressure loss of the reaction tube filled with the catalyst and blockage of the reaction tube.

As described above, according to the catalyst of the present invention, since the activity and selectivity of the catalyst can be maintained in a high state for a long time, acrylic acid and / or acrylate ester is used as a raw material by using lactic acid and / or its derivative as a raw material. In addition, it is possible to produce a stable and high yield over a long period of time.

[Method for producing acrylic acid and / or acrylic ester]
Next, the manufacturing method of acrylic acid and / or acrylic acid ester of this invention is demonstrated. The method for producing acrylic acid and / or acrylic ester of the present invention comprises a step of obtaining acrylic acid and / or acrylic ester from lactic acid and / or a derivative thereof by dehydration reaction in the presence of the catalyst of the present invention. is there. That is, the method for producing acrylic acid and / or acrylic ester of the present invention uses a catalyst containing a phosphate compound containing both alkali metal and alkaline earth metal elements to dehydrate lactic acid and / or its derivatives. It has the process of obtaining acrylic acid and / or acrylic ester by reaction. The catalyst of the present invention can be used for producing acrylic acid and / or an acrylate ester by dehydration reaction from lactic acid and / or a derivative thereof. Details of the catalyst are as described above. According to the production method of the present invention, acrylic acid and / or an acrylic ester can be produced with high selectivity from lactic acid and / or a derivative thereof.

(Reaction raw materials)
The lactic acid and / or derivative thereof used as a reaction raw material can be either produced using a fermentation method which is a general production method or produced by a chemical method. Lactic acid and / or derivatives thereof may be derived from biomass, which leads to a reduction in environmental burden.

Lactic acid is usually distributed in the form of an aqueous solution, and may be used as it is, may be further diluted with water, or may be used by appropriately concentrating after removing moisture using an operation such as evaporation. Good. As the water used for the dilution, ion exchange water, pure water, normal tap water, or the like may be used, or waste water generated in the manufacturing process may be recycled. In addition to the lactic acid monomer, the lactic acid used in the reaction may contain a lactic acid derivative. Examples of the lactic acid derivative include lactic acid oligomers and condensates of lactic acid such as lactide, lactic acid salts, and lactic acid. Examples include esters. Examples of the lactate include ammonium lactate, lithium lactate, sodium lactate, potassium lactate, magnesium lactate, and calcium lactate. Examples of the lactate include methyl lactate, ethyl lactate, butyl lactate, and 2-ethylhexyl lactate. Can be mentioned. In addition, the derivative | guide_body of lactic acid is not limited to this illustration. Lactic acid derivatives may be used with addition of water or other solvents, or may be used as they are, and are appropriately selected and used.

When lactic acid or the like is handled as a solution such as an aqueous solution, the concentration of lactic acid in the solution is preferably 10% by mass or more, more preferably 30% by mass or more from the viewpoint of process efficiency. In order to obtain a high reaction yield, the concentration of lactic acid is preferably 90% by mass or less, more preferably 80% by mass or less. The concentration of lactic acid is a concentration containing a lactic acid monomer and an oligomer of lactic acid, lactide, a salt thereof, and a lactic acid ester, and is a concentration determined by the method described in JIS K 8726.

(Reactor)
The dehydration reaction of lactic acid and / or its derivative is preferably carried out by introducing lactic acid and / or its derivative into a reactor provided with the catalyst of the present invention. The type of the reactor is not particularly limited, and examples thereof include a stirring reactor, a fixed bed reactor, a fluidized bed reactor, a spouted bed reactor, and the like, and a fixed bed reactor is preferably used.

The fixed bed reactor includes a reaction tube filled with a solid catalyst, and gaseous lactic acid and / or a derivative thereof is introduced into the reaction tube, and the lactic acid and / or the derivative thereof is obtained by a gas phase catalytic reaction. It is dehydrated to obtain acrylic acid and / or an acrylic ester. Gaseous lactic acid and / or its derivative can be produced, for example, by heating an aqueous solution containing lactic acid and / or its derivative at the inlet side of the reaction tube or upstream of the reaction tube.

The fixed bed reactor includes, for example, a raw material gas inlet provided at the reactor inlet, a product outlet provided at the reactor outlet, and a heat medium for heating or removing the reaction tube from the outside of the reactor. And a heat medium outlet for discharging the heat medium and a heat medium outlet for discharging the heat medium. Further, the reaction tube may be heated with an electric heater or the like instead of the heat medium.

The reaction tube provided in the fixed bed reactor may be a single reaction tube or a plurality of reaction tubes. When a plurality of reaction tubes are arranged, the reaction tubes are usually metal tubes having substantially the same shape. The reaction tube may be coiled or the like, but a straight straight tube is usually used. The straight pipe may be either a horizontal arrangement or a vertical arrangement, but is usually a vertical type that is arranged in the vertical direction and allows the source gas to pass in the vertical direction.

(Reaction conditions)
The reaction temperature may be appropriately determined according to the catalyst used and the conversion and selectivity of the reaction, but in order to obtain a sufficient reaction rate, it is usually 250 ° C. or higher, more preferably 300 ° C. or higher, more preferably 350 ° C. or higher. Moreover, in order to suppress the side reaction and to obtain sufficient selectivity of the target compound, the reaction temperature is preferably 500 ° C. or lower, more preferably 450 ° C. or lower, and further preferably 400 ° C. or lower. The reaction temperature means the temperature of a heat medium or heater for controlling the temperature of the reactor.

Although the pressure in the reactor is not particularly limited, it is preferably 30 kPa or more, more preferably 60 kPa or more from the viewpoint of equipment required for decompression and cooling of the reaction gas. In addition, from the viewpoint of materials required for high pressure equipment and reactors, 200 kPa or less is preferable, and 150 kPa or less is more preferable.

In the case of using a carrier gas, an inert gas can be used, preferably nitrogen, argon or helium, and more preferably nitrogen from an economical viewpoint. Also, water vapor can be used as the carrier gas. In this case, water vapor obtained by evaporating water in an aqueous solution such as lactic acid as a raw material can be used as it is, or water vapor can be additionally used.

The flow rate of the reaction gas may be appropriately adjusted in consideration of the raw material concentration, the amount of carrier gas, the performance of the catalyst, the productivity, etc., but when expressed in terms of gas space velocity per unit volume of catalyst (GHSV), it is usually 50 to 20000 h. ⁻¹ , preferably 100 to 10000 h ⁻¹ , more preferably 150 to 6000 h ⁻¹ . In addition, GHSV is calculated by the following formula (in the following formula, 24800 represents the volume (mL / mol) of ideal gas per mole in the standard state (SATP)):
GHSV (h ⁻¹ ) = {(Amount of lactic acid to be supplied (mol / h) + Amount of water to be supplied (mol / h)) × 24800 + flow rate of carrier gas (mL / h)} / catalyst filling volume (mL).

According to the production method of the present invention, acrylic acid can be obtained by dehydrating lactic acid. When a lactic acid ester is used as a raw material, an acrylic acid ester can be obtained through a dehydration reaction, and the resulting acrylic acid ester can be further hydrolyzed to obtain acrylic acid. Examples of the acrylate ester include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like, but are not limited to such examples.

Further, according to the production method of the present invention, it is possible to obtain the effect of suppressing the accumulation on the catalyst such as coke. However, when coke occurs, the catalyst may be regenerated by a known method such as aeration. Good.

(Purification)
The reaction gas obtained by the dehydration reaction contains by-products such as water, acetaldehyde, propionic acid, 2,3-pentanedione, hydroxyacetone, and acetic acid in addition to the main products such as acrylic acid and acrylic ester. Although included, these by-products can be appropriately separated and removed by a general purification method to obtain high-purity acrylic acid or acrylic acid ester. For example, a compound having a low boiling point such as acetaldehyde can be separated as a light boiling gas by gas-liquid separation by appropriately adjusting the condensation temperature of the reaction gas. The condensed high-boiling liquid can be separated and removed by-products by appropriately using a separation operation such as distillation or crystallization to obtain high-purity acrylic acid or acrylic acid ester.

This application claims the benefit of priority based on Japanese Patent Application No. 2013-155055 filed on July 25, 2013. The entire contents of the specification of Japanese Patent Application No. 2013-155055 filed on July 25, 2013 are incorporated herein by reference.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

(1) Preparation of catalyst (1-1) Catalyst preparation example 1: Preparation of catalyst containing NaCaPO ₄ 1890 g of an aqueous solution in which 250 g of trisodium phosphate dodecahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved was stirred at 60 ° C. Then, 813 g of an aqueous solution in which 155 g of calcium chloride dihydrate (manufactured by Kanto Chemical Co., Ltd.) was dissolved was dropped over 15 minutes. The mixture was stirred as it was for 1 hour, air-cooled to 40 ° C. or lower, and then filtered under reduced pressure to obtain a white precipitate. The operation of adding 1000 g of water to the precipitate, stirring and washing for 30 minutes, and filtering under reduced pressure was repeated twice. This precipitate was dried in an air atmosphere at 120 ° C. for 24 hours to obtain Intermediate 1.

Next, 17.9 g of an aqueous solution in which 0.249 g of sodium nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved was added to intermediate 1 (25.0 g), kneaded, and evaporated to dryness at 90 ° C. Furthermore, after drying for 24 hours at 120 ° C. in an air atmosphere, a fired product was obtained by firing at 500 ° C. for 6 hours. The fired product was analyzed using an X-ray diffractometer (XRD, X'Pert PRO MPD manufactured by PANalytical), and was found to be a mixture containing NaCaPO ₄ and calcium hydroxyapatite. The XRD analysis result is shown in FIG. 1, and its enlarged view is shown in FIG. In FIG. 2, main peaks corresponding to NaCaPO ₄ are indicated by arrows. The fired product obtained is compressed and molded by a hydraulic press and crushed, and then sieved using a sieve having an opening of 0.85 mm and 2.0 mm, and the fired product is classified to a range of 0.85 to 2.0 mm. Was used as a catalyst.

(1-2) Catalyst Preparation Example 2: Preparation of a catalyst containing Na ₂ CaP ₂ O ₇ Calcium chloride 2 water while stirring 871 g of an aqueous solution in which 100 g of tetrasodium diphosphate (Wako Pure Chemical Industries, Ltd.) was dissolved was stirred at 50 ° C. 430 g of an aqueous solution in which 122 g of a Japanese product (manufactured by Kanto Chemical Co., Ltd.) was dissolved was dropped over 15 minutes. The mixture was stirred as it was for 1 hour, air-cooled to 40 ° C. or lower, and then filtered under reduced pressure to obtain a white precipitate. The operation of adding 700 g of water to the precipitate, stirring and washing for 30 minutes, and filtering under reduced pressure was repeated twice. This precipitate was dried at 120 ° C. for 24 hours in an air atmosphere to obtain Intermediate 2.

Next, Intermediate 1 (60.7 g) and Intermediate 2 (60.7 g) were suspended and mixed in 700 mL of water for 1 hour, and filtered under reduced pressure. The obtained mixture was dried at 120 ° C. for 24 hours in an air atmosphere, and then fired at 500 ° C. for 6 hours to obtain a fired product. The fired product was analyzed using an X-ray diffractometer (XRD, X'Pert PRO MPD manufactured by PANalytical), and was found to be a mixture containing Na ₂ CaP ₂ O ₇ and calcium hydroxyapatite. The XRD analysis results are shown in FIG. In FIG. 3, the main peaks corresponding to Na ₂ CaP ₂ O ₇ are indicated by arrows. The fired product obtained is compressed and molded by a hydraulic press and crushed, and then sieved using a sieve having an opening of 0.85 mm and 2.0 mm, and the fired product is classified to a range of 0.85 to 2.0 mm. Was used as a catalyst.

(1-3) Catalyst Preparation Example 3: Preparation of Calcium Hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ) Catalyst While heating 500 g of water to 70 ° C. and stirring, 226 g of calcium nitrate tetrahydrate was added. 531 g of a dissolved aqueous solution, 527 g of an aqueous solution containing 83.5 g of diammonium hydrogen phosphate, and 192 g of 28% by mass ammonia water were simultaneously added dropwise over 5 hours, and then aged for 15 hours, followed by pressure filtration to obtain a white precipitate. It was. The operation of adding 700 g of water to the precipitate, stirring and washing for 30 minutes, and filtration under pressure was repeated twice. This precipitate was dried at 120 ° C. for 24 hours in an air atmosphere to obtain Intermediate 3. A fired product was obtained by firing at 500 ° C. for 6 hours. The fired product was confirmed to be calcium hydroxyapatite by analysis using an X-ray diffractometer (XRD, X'Pert PRO MPD manufactured by PANalytical). The XRD analysis result is shown in FIG. 4, and its enlarged view is shown in FIG. The obtained fired product is compression-molded with a hydraulic press and crushed, and then sieved using a sieve having an opening of 0.85 mm and 2.0 mm, and the fired product is classified into a range of 0.85 to 2.0 mm. Was used as a catalyst.

(2) Production Example of Acrylic Acid from Lactic Acid (2-1) Method Using the catalyst produced in the above Catalyst Preparation Examples 1 to 3, lactic acid was dehydrated by the following atmospheric pressure fixed bed flow reaction mode. Acrylic acid was produced. A fixed bed reactor was prepared by filling 10 mL of a catalyst in a stainless steel reaction tube (inner diameter 10 mm, length 310 mm), and this reactor was immersed in a night bath controlled at a predetermined reaction temperature. Thereafter, nitrogen gas was allowed to flow through the reactor at a flow rate of 157 mL / min for 30 minutes, and then a reaction gas (reaction gas composition: 7.6 mol% lactic acid, water consisting of a vaporized gas of 36 mass% lactic acid aqueous solution and nitrogen gas) 68.0 mol%, nitrogen 24.4 mol%) was allowed to flow at a flow rate (GHSV) of 3900 h ⁻¹ . The reaction time is defined as the time from when the reaction gas is circulated through the reactor to the start of the reaction until the reaction gas is collected for sampling. During sampling, the effluent gas from the reactor is collected for 30 minutes. And collected by cooling and absorbing in water. Hereinafter, the cooling absorption material of the collected outflow gas is referred to as “outflow”.

The sampled effluent was collected by a gas chromatography (GC) apparatus (GC-2010 manufactured by Shimadzu Corporation) equipped with a FID in the detector and a liquid chromatography (LC) apparatus (UPLC manufactured by Waters) equipped with a PDA in the detector. Quantitative analysis was performed. An internal standard method was adopted for quantitative analysis. From the quantitative analysis by LC, the lactic acid conversion rate, and from the quantitative analysis result by GC, acrylic acid selectivity, acetaldehyde selectivity, propionic acid selectivity, 2,3-pentanedione selectivity, and hydroxyacetone selectivity were calculated. These calculation formulas are as follows.

Lactic acid conversion (%) = (1− (moles of lactic acid in the effluent / moles of lactic acid introduced into the reactor in 30 minutes)) × 100;
Acrylic acid selectivity (%) = (moles of acrylic acid in the effluent / (moles of lactic acid introduced into the reactor in 30 minutes × lactic acid conversion (%) / 100)) × 100;
Acetaldehyde selectivity (%) = (moles of acetaldehyde in the effluent / (moles of lactic acid introduced into the reactor in 30 minutes × lactic acid conversion (%) / 100)) × 100;
Propionic acid selectivity (%) = (moles of propionic acid in the effluent / (moles of lactic acid introduced into the reactor in 30 minutes × lactic acid conversion (%) / 100)) × 100;
2,3-pentanedione selectivity (%) = (number of moles of 2,3-pentanedione in the effluent / (number of moles of lactic acid introduced into the reactor in 30 minutes × lactic acid conversion (%) / 100 )) × 100;
Hydroxyacetone selectivity (%) = (number of moles of hydroxyacetone in the effluent / (number of moles of lactic acid introduced into the reactor in 30 minutes × lactic acid conversion (%) / 100)) × 100.

(2-2) Results An example in which acrylic acid was produced from lactic acid using the catalyst obtained in Catalyst Preparation Example 1, acrylic acid was produced from lactic acid using the catalyst obtained in Example 1 and Catalyst Preparation Example 2. The results of Examples 1 and 2 and Comparative Example are shown in Table 1 as an example in which acrylic acid was produced from lactic acid using the catalyst obtained in Example 2 and Catalyst Preparation Example 3. FIG. 6 shows the results of changes in the conversion rate of lactic acid and the reaction selectivity of each of the above components with respect to the reaction time (TOS) in Example 2.

As can be seen from Table 1, Example 1 using a catalyst containing NaCaPO ₄ has a reaction time of 3. compared with a comparative example using a Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ catalyst containing no alkali metal. At 0 hour, the conversion of lactic acid and the selectivity of acrylic acid were high, and the selectivity of by-products was kept low. Further, in the comparative example, the acrylic acid selectivity was lower than 40% at the reaction time of 3.0 hours, whereas in Example 2 using the catalyst containing Na ₂ CaP ₂ O ₇ , Table 1 and FIG. As is clear from FIG. 6, the acrylic acid selectivity of 55% or more was maintained even at a reaction time of 98.5 hours.

Claims

A catalyst for producing acrylic acid and / or an acrylic ester from lactic acid and / or a derivative thereof by a dehydration reaction,
A catalyst comprising a phosphate compound containing both alkali metal and alkaline earth metal elements.
The catalyst according to claim 1, wherein the phosphate compound is an orthophosphate compound and / or a pyrophosphate compound.
The catalyst according to claim 1 or 2, wherein the alkali metal is sodium.
The catalyst according to any one of claims 1 to 3, wherein the alkaline earth metal is calcium.
Using a catalyst containing a phosphate compound containing both alkali metal and alkaline earth metal elements, a step of obtaining acrylic acid and / or an acrylic ester from lactic acid and / or its derivative by dehydration reaction A method for producing acrylic acid and / or acrylic ester characterized by the above.
The production method according to claim 5, wherein the phosphate compound is an orthophosphate compound and / or a pyrophosphate compound.
The method according to claim 5 or 6, wherein the alkali metal is sodium.
The production method according to any one of claims 5 to 7, wherein the alkaline earth metal is calcium.