JP3995429B2 - Method for producing lower alkyl ester - Google Patents

Description

【００５５】
実施例１〜７と比較例１〜５との比較より、ペロブスカイト型構造を有する複合金属酸化物からなる触媒を使用してメチルエステルを製造することで、当該触媒を使用しない場合と比較して、格段にメチルエステルの生成率が向上することが分かる。
【００５６】
【発明の効果】
本発明によれば、油脂類、特に廃食油に含まれる主としてトリグリセリドから、ディーゼル燃料油等として有効利用できる低級アルキルエステルを高効率に、しかも工業規模で製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a lower alkyl ester.
[0002]
[Prior art]
Currently, a large amount of various edible oils are used in Japan, and some of the used oil (waste edible oil) is reused as raw materials for soap, etc., but most of it is not recovered and is disposed of as a waste treatment plant. The actual situation is that it is transported to the city and incinerated with combustible waste or landfilled with noncombustible waste.
[0003]
On the other hand, it has long been known that fatty acid alkyl esters can be obtained by transesterifying monoglycerides, diglycerides, and triglycerides, which are the main components of vegetable oils, with alkyl alcohols (for example, “Organic Chemistry Handbook”, Gihodo Publishing, 1988). , P1407-p1409). In addition, various techniques for producing alkyl esters that can be used as diesel fuel oil from vegetable fats and oils, waste cooking oils, and the like by using this reaction have been studied so far (for example, JP-A-7-197047 and 7). No. 310090, etc.), these techniques do not provide an alkyl ester that can satisfy the current quality assurance method for light oil.
[0004]
By the way, since the transesterification reaction is an equilibrium reaction, the yield is increased by shifting the equilibrium to the production system by using a large amount of one of the raw material alkyl alcohols or by removing glycerin produced as a side reaction product. Like. In addition, it is said that the gas phase reaction is more advantageous in equilibrium than the liquid phase reaction. Furthermore, in order to increase the reaction rate, a catalyst is generally used.
[0005]
In general, acid catalysts are often used in production methods for acetic acid, higher fatty acids, unsaturated carboxylic acids, and the like, which are typical industrial processes for transesterification. For example, protic acids such as sulfuric acid and phosphoric acid are used as esterification catalysts for non-aromatic carboxylic acids, and boric acid and sulfuric acid are used for esterification of phenolic acids. However, since these reactions are basically a homogeneous reaction system in which the catalyst is dissolved in the reaction solution, there is a problem that it is difficult to separate and recover the catalyst from the product solution.
[0006]
Solid acidic catalysts are also often used. For transesterification of terephthalic acid and methacrylic acid, SO_Four ^2--TiO₂TiO₂-SiO₂, Al₂(SO_Four)_Three/ SiO₂・ Al₂O_ThreeIn addition, sulfonic acid ion exchange resins and the like are used. Heteropoly acids are also said to be good esterification catalysts, and SiO₂And supported on activated carbon, SiO as a gas phase catalyst₂-Al₂O_ThreeIt is known to exhibit higher activity than solid phosphoric acid. Furthermore, clay minerals are also used as catalysts. Since these solid acidic catalyst and mineral catalyst do not need to be separated from the product solution, they are excellent in terms of simplification of the reaction apparatus. However, these industrial catalysts have a decisive disadvantage that the activity of fats and oils for transesterification is low, and the above process has not been put to practical use on an industrial scale.
[0007]
As a technique in which a solid acidic catalyst is applied to a transesterification reaction of fats and oils, for example, a technique as disclosed in JP-A-6-313188 has been proposed. Catalysts used in this technology include single or mixed metal oxides, metal sulfates, metal phosphates, immobilized acids supported or immobilized on a support, natural minerals and layered compounds, solid heteropolyacids, Strong acids, synthetic zeolites, ion exchange resins and the like are mentioned. However, in this technique as well as the conventional method described above, the catalytic activity for the transesterification reaction of fats and oils is low, and in order to achieve a high yield, the ratio of the solid acidic catalyst in the reaction system is increased. Or it was necessary to lengthen the reaction time.
[0008]
A basic catalyst is also used in the transesterification reaction, and it is known that a metal alcoholate is effective as the basic catalyst. As such metal alcoholates, sodium alcoholates and potassium alcoholates are generally used. Moreover, sodium hydroxide, potassium hydroxide, sodium carbonate, etc. are also used as a basic catalyst, These have shown high activity to transesterification of fats and oils. However, since the conventional basic catalyst acts in the state of being dissolved in the reaction solution in the same manner as the acidic catalyst described above, it is dissolved in the product solution, and its separation and recovery are difficult. Has not been resolved.
[0009]
In addition, attempts have been made to use a solid basic catalyst for transesterification, and an ion exchange resin having an amine base as such a solid basic catalyst has been proposed (for example, JP-A-62-218495). ). With such technology, the problem of separation and recovery of the catalyst basically does not occur. However, this technique is carried out in a reaction system in which the alcohol is used in excess and the triglyceride concentration is about 0.1 to 3% by weight, the activity is extremely low, and the reaction temperature is the durability of the ion exchange resin. From the point, it is not practical because it is limited to 60 ° C. or less.
[0010]
Recently, the use of a basic solid catalyst comprising a carboxylic acid compound and iron oxide, or a potassium compound and zirconium oxide has been disclosed (Japanese Patent Laid-Open No. 2000-44984), but the catalytic activity is sufficient. Not practical.
[0011]
[Problems to be solved by the invention]
The present invention can produce a lower alkyl ester that can be effectively used as a diesel fuel oil, etc., mainly from triglycerides contained in fats and oils, particularly waste edible oil, with high reaction efficiency, and simplifies or omits the catalyst separation and recovery process. An object of the present invention is to provide a process for producing a lower alkyl ester that can be used on an industrial scale.
[0012]
[Means for Solving the Problems]
That is, the present invention
[1] When a lower alkyl ester is produced by performing a transesterification reaction between an oil and fat and a lower alcohol in the presence of a catalyst, a catalyst comprising a composite metal oxide having a perovskite structure is used. A method for producing a lower alkyl ester,
[2] The method according to [1] above, wherein the composite metal oxide comprises at least one selected from the group consisting of Ca, Sr and Ba,
[3] The method according to [1] or [2], wherein the catalyst further contains 1 to 10% by mass of a cesium compound in terms of cesium, and
[4] The method according to any one of [1] to [3] above, wherein a solid catalyst formed by forming a catalyst is charged, and a transesterification reaction is performed using a fixed fixed bed flow reactor.
About.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The method for producing a lower alkyl ester of the present invention is characterized by using a catalyst comprising a composite metal oxide having a perovskite structure as a catalyst. Since such a catalyst is used, it is possible to carry out a transesterification reaction between an ester (mainly triglyceride) contained in oils and fats and a lower alcohol with high efficiency even under mild conditions. It becomes possible to produce a lower alkyl ester that can be effectively used as an oil or the like and satisfies the quality assurance method for light oil on an industrial scale. In addition, the catalyst is a solid and does transesterification. For example, it does not dissolve in the reaction solution, and can be easily separated and removed from the reaction system by a simple operation such as filtration after the reaction is completed. -The recovery process can be simplified or omitted. Therefore, the lower alkyl ester can be easily purified, and the obtained glycerin can be reused immediately without any problem of remaining catalyst in the phase-separated glycerin.
[0014]
The “lower alkyl ester satisfying the quality assurance method for light oil” specifically refers to a lower alkyl ester having a sulfur content of 0.2% or less, a cetane index of 45 or more, and a 90% distillation temperature of 360 ° C. or less. .
[0015]
The fats and oils used as raw materials in the present invention are not particularly limited. For example, rapeseed oil, sesame oil, soybean oil, corn oil, sunflower oil, palm oil, palm kernel oil, coconut oil, safflower oil, linseed oil, cottonseed oil, tung oil, castor oil, beef tallow, general oils and fats, restaurants, food factories And waste cooking oil discarded from ordinary households. Moreover, these fats and oils can also be used individually or in mixture of 2 or more types, The fats and oils processed product which has the said fats and oils as a main component can also be used as a raw material. In the present invention, it is preferable to use waste cooking oil from the viewpoint of reusing resources.
[0016]
Although the quality of the fats and oils to be used is not particularly limited, it is preferable to use fats and oils having a low moisture and solid content from the viewpoint of achieving a highly efficient transesterification reaction. Therefore, when using waste cooking oil as a raw material, it is preferable to perform a pretreatment for removing the contained moisture and solid content. In addition, the waste edible oil to be used may contain a large amount of an acidic substance. From the viewpoint of preventing the catalytic activity from being inhibited by the acidic substance, it is preferable to perform deoxidation as a pretreatment. In addition, all the said pre-processing can be performed in accordance with a well-known method.
[0017]
The lower alcohol used in the present invention is an alcohol having a saturated linear or branched hydrocarbon skeleton having 1 to 8, preferably 1 to 5 carbon atoms, such as methyl alcohol, ethyl alcohol, propyl alcohol. , Isopropyl alcohol, butyl alcohol, t-butyl alcohol and the like. Especially, it is preferable to use at least 1 sort (s) chosen from the group which consists of methyl alcohol, ethyl alcohol, propyl alcohol, and isopropyl alcohol from a viewpoint of manufacturing a good quality lower alkyl ester as diesel fuel oil.
[0018]
The catalyst used in the present invention is a catalyst containing a composite metal oxide having a perovskite structure, and the composite metal oxide has the general formula ABO._n(Wherein A is an alkaline earth metal atom, B is a transition metal atom, and n is an integer of 3 or more). From the viewpoint of expression of the desired effect of the present invention, A is preferably at least one selected from the group consisting of Ca, Sr and Ba, and B is Ti, Mn, V, Fe, Cu, Y and a lanthanoid metal atom. And at least one selected from the group consisting of La. Furthermore, the catalyst is a composite metal oxide in which A is at least one selected from the group consisting of Ca, Sr and Ba, and B is at least one selected from the group consisting of Ti, Mn, Y and La More preferably, it contains The perovskite structure is generally ABO._ThreeThis is the structure that occurs when the A ion is quite large with the composition₊₁B₊₅O_Three, A₊₂B₊₄O_Three, A₊₃B₊₃O_ThreeThe structure of a compound perovskite compound containing a plurality of A or B ions is determined by X-ray diffraction.
[0019]
Further, the catalyst preferably further contains a cesium (Cs) compound. Examples of the Cs compound include Cs.₂O, CsCl, CsF, Cs₂CO_Three, CsNO_Three, Cs₂SO_FourEtc. Although content of the said compound is not specifically limited as long as the desired effect of this invention is acquired, Preferably it is 1-10 mass% in conversion of the mass of Cs, More preferably, it is 3-8 mass%. As a catalyst containing a Cs compound, among them, together with the Cs compound, A is at least one selected from the group consisting of Ca, Sr and Ba, and B is selected from the group consisting of Ti, Mn, Y and La. It is preferable to contain at least one mixed metal oxide.
[0020]
The catalyst containing a composite metal oxide having a perovskite structure used in the present invention is composed of an oxide of a basic metal atom having a relatively large ionic radius, such as an alkaline earth metal atom or a lanthanoid metal atom. Is a solid strong basic catalyst that is presumed to form a stable structure, and since the composite metal oxide has a perovskite structure, the basic metal oxidation with a large ionic radius It is considered that the product is structurally stabilized and hardly changes in structure when used as a catalyst in the reaction. Further, the compound itself having a perovskite structure has a strong basicity, but even if a compound containing Cs having a large ionic radius is added, the perovskite structure is stably maintained, and both basic additivity is high. Therefore, it is presumed that the basicity becomes stronger by further adding a Cs compound to the catalyst. Therefore, a material system having a remarkably high basic strength as a basicity that can be expected as a composite metal oxide. Thus, a catalyst having more excellent activity can be obtained. Therefore, according to the catalyst of the present invention, high catalytic activity is exhibited in the transesterification reaction, and a desired lower alkyl ester that can be effectively used as a diesel fuel oil or the like, which has been difficult in the past, can be obtained with high efficiency. In addition, since it is solid, separation and recovery of the catalyst after the completion of the reaction is facilitated, and unlike the known solid basic catalyst comprising an ion-exchange resin having an amine base, a normal transesterification reaction is performed. There are no restrictions on the reaction temperature under the conditions.
[0021]
The production of the catalyst according to the present invention is carried out by mixing and supporting each metal as a raw material by a coprecipitation method, an impregnation method, a kneading method, and the like, followed by firing. Specifically, for example, an aqueous solution containing each metal as a raw material is mixed and stirred, and after aging, a precipitate is obtained, and the precipitate is washed, filtered, dried, and fired. Further, it is possible to form a catalyst obtained as a powder to obtain a so-called solid catalyst. The solid catalyst is preferable because the possibility of the catalyst being mixed into the reaction solution can be greatly reduced, and the catalyst separation / recovery step after the completion of the reaction does not need to be substantially performed.
[0022]
For the preparation of an aqueous solution containing each metal as a raw material, carbonates, nitrates, sulfates, formates, acetates and the like containing A shown in the above general formula, and carbonates, nitrates containing B shown in the above general formula, Sulfates, formates, acetates and the like can be used. The concentration of the metal in the aqueous solution is not particularly limited as long as an aqueous solution of the metal is obtained. Subsequently, the aqueous solution containing each metal is preferably mixed and stirred at 30 to 60 ° C. The mixing is performed in the presence of an alkali metal from the viewpoint of producing a precipitate of a hydroxide of a uniform composition from each metal salt (the alkali metal serves as a precipitating agent to increase the pH of the aqueous solution, It is not contained in the catalyst). For example, an aqueous solution of Na salt may be prepared and mixed with an aqueous solution containing each metal as the raw material. Mixing may be performed by putting each obtained aqueous solution into, for example, one container all at once. However, from the viewpoint of efficiently promoting the formation of the catalyst, it becomes a raw material for the aqueous solution containing an alkali metal. It is preferable to carry out by dripping the aqueous solution containing each metal. In mixing, it is desirable that the A component metal and the B component metal are in a molar ratio, preferably 1: 1. Further, the alkali metal is preferably a molar ratio of the alkali metal to the total amount of the A component and B component metals, preferably 1: 1 to 1.5: 1. The stirring method is not particularly limited.
[0023]
Aging is a step of growing nuclei formed during precipitation, and is preferably carried out for 1 to 4 hours in the same temperature range as during mixing and stirring of the aqueous solution. By this step, the formed solid particles of the catalyst are obtained as a precipitate, and the precipitate is washed with water and filtered. After washing, it is suitably dried by air drying or the like preferably at 30 to 80 ° C., and further preferably calcined in a muffle furnace at 500 ° C. or higher, more preferably 800 to 1000 ° C. for 1 to 4 hours.
[0024]
When the Cs compound is contained in the catalyst, for example, the catalyst powder obtained after drying and the Cs compound, for example, Cs₂O_Three, Cs₂CO_Three, CsNO_Three, Cs₂SO_Four, CsCl, CsCOOCH_Three, Cs₂It can be carried out by appropriately mixing a powder such as O and then firing in the same manner as described above.
[0025]
The catalyst can be formed by a known method. In the present specification, “molding” includes a mode in which the catalyst powder is supported on a specific carrier as well as a mode in which the catalyst powder is adjusted to a certain shape using a press or the like.
[0026]
The shape of the solid catalyst obtained by molding the catalyst according to the present invention is not particularly limited, and may be appropriately selected depending on the application. For example, it may be tablet-shaped, ring-shaped, pellet-shaped, honeycomb-shaped, corrugated-shaped, or may be a carrier such as a ceramic or metal honeycomb coated with a slurry containing catalyst powder. .
[0027]
As a method for producing the lower alkyl ester of the present invention, even if it is a continuous type in which the raw material is continuously supplied to carry out the transesterification reaction, the raw material is supplied in an amount required for one batch, and the transesterification reaction is performed once A batch type may be used. In the case of a continuous type, for example, a fixed bed flow type reactor for performing a transesterification reaction, which is filled and fixed with a solid catalyst formed by molding the catalyst (powder) according to the present invention, is used. The raw oils and fats and the lower alcohol are continuously supplied to the product, and the lower alkyl ester and glycerin as reaction products, and the remaining fats and alcohols and unreacted substances are discharged. On the other hand, in the case of a batch type, for example, a reactor for performing a transesterification reaction is used, and after the required amounts of raw oils, alcohols, and catalysts per batch are charged into the reactor, the reaction is performed. The reaction product can be extracted by extracting a reaction mixture containing a lower alkyl ester, glycerin, which is a reaction product, and residual oils, alcohols, and catalysts, which are unreacted. Among these, the embodiment in which the solid catalyst formed by molding the catalyst (powder) according to the present invention is filled, the transesterification reaction is carried out using a fixed fixed bed flow reactor, and the production of the lower alkyl ester is carried out is the reaction. It is preferable because the process can proceed with high efficiency and the step of separating and recovering the catalyst after completion of the reaction can be omitted. In the case of the batch type, the catalyst can be easily removed by filtration or the like, and the catalyst separation / recovery process can be simplified.
[0028]
Below, the case where the said fixed bed flow-type reactor which is a preferable aspect as a manufacturing method of the lower alkyl ester of this invention is used is demonstrated in detail. “Parts” represents “parts by weight” unless otherwise specified.
[0029]
The amount of lower alcohol to be added to the fats and oils is preferably 10 to 100 parts, more preferably 10 to 40 parts with respect to 100 parts of the fats and oils. However, since the amount of lower alcohol charged relative to 100 parts of the raw oil and fat varies depending on the average molecular weight of the oil and fat, in that case, the amount is generally expressed as a multiple of the chemical equivalent calculated by the following equation (1). be able to. That is, when the average molecular weight of fats and oils is Mo and the average molecular weight of the lower alcohol is Ma, the equivalent charge amount Wa (parts) of the lower alcohol is represented by the following formula:
Wa = 100 / Mo × 3 × Ma (1)
Is calculated by The lower alcohol is preferably charged in a ratio of 1.2 times to 10 times, more preferably 1.5 times to 5 times the equivalent charge amount Wa calculated by the formula (1). If the charging ratio of alcohol is within such a range, the transesterification reaction proceeds sufficiently, which is preferable from an economical viewpoint. The average molecular weight is calculated based on the component composition of fats and oils and lower alcohols as raw materials.
[0030]
For example, when the average molecular weight of fats and oils is 880 and the lower alcohol is methyl alcohol (average molecular weight 32), methyl alcohol is preferably 12 to 100 parts, more preferably 15 parts, per 100 parts of fats and oils. Prepare 50 parts.
[0031]
The amount of the solid catalyst charged in the reactor is not particularly limited as long as the desired transesterification efficiency can be obtained, but is generally preferably 0.5 to 100 parts with respect to 100 parts of fats and oils. ~ 30 parts are more preferred. If the amount of the solid catalyst charged is within such a range, the transesterification reaction proceeds sufficiently, which is preferable from an economical viewpoint.
[0032]
Examples of the reactor, that is, a container that provides a reaction field for the transesterification reaction, include a flask, a steel container, a steel pipe, a static mixer, and a stirring tank. The material of the reactor is not particularly limited, and glass, steel, stainless steel, Ni alloy, Ti alloy, glass lining steel, polymer lining steel, ceramic lining steel and the like can be used.
[0033]
The fats and oils and lower alcohol may be supplied to the reactor, for example, from each raw material tank separately via a raw material supply line connecting the raw material tank and the reactor (Aspect 1), Or fats and oils and a lower alcohol may be mixed beforehand in one raw material tank, and both components may be simultaneously supplied through one raw material supply line (mode 2). In addition, the preparation order of each raw material is not specifically limited. Moreover, the aspect 2 intends all the aspects in which both components are mixed and supplied to the reactor at the same time. For example, although the raw material tank is provided for each raw material, the raw material extending from each raw material tank It also includes an embodiment in which the supply lines are combined in the middle to form one, and so-called line mixing is performed and both components are supplied to the reactor simultaneously.
[0034]
In the case of the aspect 1, the supply amount of fats and oils with respect to the solid catalyst in the reactor is liquid space velocity (LHSV), preferably 0.1 to 10 / hr. Further, the supply amount of the lower alcohol is preferably such an amount that the amount of the lower alcohol charged to the fats and oils falls within the above preferable range, and preferably 0.01 to 6 / hr in terms of liquid space velocity (LHSV). .
[0035]
In the case of the embodiment 2, the fats and oils and the lower alcohol are preferably mixed in advance so that the charge amount of the lower alcohols to the fats and oils is within the above preferred range, and the resulting mixture is obtained with respect to the solid catalyst in the reactor. At a liquid hourly space velocity (LHSV), preferably 0.7-8 / hr.
[0036]
The transesterification reaction is performed by heating the supplied raw materials to a predetermined reaction temperature in the reactor. The heating method may be performed by charging each raw material while heating in a heat exchanger at the time of charging, or may be performed by heating the reaction reactor from the outside at the start of charging. As reaction temperature, Preferably it is 25 to 300 degreeC, More preferably, it is 40 to 200 degreeC, More preferably, it is 55 to 60 degreeC. The reaction pressure corresponds to the vapor pressure at the reaction temperature indicated by the volatile substance charged in the reactor, preferably 0.1 MPa to 10 MPa, more preferably 0.1 MPa to 6 MPa, and still more preferably 0.1 MPa to 1 MPa. If it is in the range of this reaction temperature and reaction pressure, the reaction rate of transesterification is sufficient, and reaction can be advanced favorable and rapidly, and is preferable. The reaction time varies depending on the reaction temperature, the type of raw material used, etc., and cannot be determined unconditionally, but is generally selected in the range of 1 minute to 24 hours.
[0037]
The reaction product obtained by the transesterification reaction in the reactor is a mixture composed mainly of lower alkyl ester of fatty acid and glycerin produced by transesterification of triglyceride and lower alcohol contained as main components in the raw oils and fats. It is. In order to separate the lower alkyl ester and glycerin from this mixture, after completion of the reaction, the obtained reaction mixture is cooled to a desired temperature and allowed to stand at that temperature or room temperature, or as it is at room temperature. Although a stationary layer separation method in which the lower alkyl ester and glycerin are phase-separated by utilizing the difference in specific gravity between them can be applied, the centrifugal separation method described later is preferable from the viewpoint of productivity.
[0038]
Centrifugation is performed by applying the reaction mixture cooled to a desired temperature to the desired temperature after completion of the reaction, and applying a centrifugal force sufficient to separate the lower alkyl ester and glycerin. The upper layer obtained after centrifugation contains contaminants such as unreacted alcohol, odor components, and colored components in addition to the lower alkyl ester as the main component. If the contaminant is removed by the purification step, a highly pure lower alkyl ester can be obtained. Examples of the adsorbent that can be used in the purification step include activated carbon, activated carbon fiber, activated clay, acidic clay, bentonite, diatomaceous earth, and activated alumina.
[0039]
The lower alkyl ester obtained as described above has a sufficiently high purity and can be used directly as a light oil alternative fuel. Further, since glycerin does not contain a catalyst, it can be reused immediately.
[0040]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, and is suitable as long as it can meet the purpose described above and below. Any changes made to the above are included in the technical scope of the present invention.
[0041]
Example 1
Na₂CO_Three  An aqueous solution prepared by dissolving 46 g in 540 ml of water was kept at 60 ° C. while stirring, and Ca (NO_Three)₂・ 4H₂22.4g of O and TiOSO_Four・ NH₂An aqueous solution in which 28.3 g of O was dissolved in 586 ml of water was added dropwise, and then aged for 1 hour to obtain a precipitate. This was filtered, washed with water, filtered, dried, and calcined at 800 ° C. for 2 hours. The X-ray diffraction image of the obtained powder had a perovskite structure. X-ray diffraction was performed by RAD-IIB manufactured by Rigaku Corporation. The fired product thus obtained was molded into a tablet (tablet) with a hydraulic press molding machine, and then cut into 2 to 3 mm as a catalyst and charged into a reactor. Subsequently, the raw material was supplied to start the reaction. The transesterification reaction was performed under the following reaction conditions.
[0042]
(Reaction conditions)
Raw oil: Edible rapeseed oil + edible soybean oil (Nisshin Oil Co., Ltd.)
Raw material lower alcohol: methyl alcohol
Amount of catalyst: 10 ml (approximately 20 parts per 100 parts by weight of fats and oils)
Oil supply (LHSV): 2 / h
Alcohol supply rate (LHSV): 0.26 / h
Alcohol charge: 13 parts by weight per 100 parts by weight of fat
Reaction temperature: 60 ° C
Reaction pressure: normal pressure (0.1 MPa)
[0043]
One hour after the start of the reaction, the product solution is sampled every hour, and after removing methyl alcohol from the methyl ester phase of the sample by an evaporator, the viscosity of the methyl ester solution is measured to determine the methyl ester production rate. Asked. The methyl ester production rate means the mass ratio (%) of the methyl ester in the methyl ester phase (including triglyceride) from which the methyl alcohol in the product liquid has been removed. The viscosity was measured with a viscosity analyzer [BL viscometer (manufactured by Tokimec)]. The amount of methyl ester in the methyl ester phase was determined in advance by preparing a calibration curve by obtaining the viscosity of a methyl ester solution having a known concentration.
[0044]
Table 1 shows the methyl ester production rate (%) obtained by analysis at 3 hours after the start of the reaction.
[0045]
Example 2
Na₂CO_Three  28.6 g is dissolved in 337 ml of water and Ca (NO_Three)₂・ 4H₂17.7 g of O and Mn (NO_Three)₂・ 6H₂A catalyst was prepared in the same manner as in Example 1 except that 21.5 g of O was dissolved in 273 ml of water. A perovskite structure was observed by X-ray diffraction. A transesterification reaction was carried out in the same manner as in Example 1, and the methyl ester production rate at this time was measured. Table 1 shows the results.
[0046]
Comparative Examples 1 and 2
CaO and TiO₂A transesterification reaction was carried out in the same manner as in Example 1 except that each was calcined at 800 ° C. as a catalyst, and the methyl ester production rate at this time was measured. As a result of X-ray diffraction, it was confirmed that the catalyst was not a perovskite structure. Table 1 shows the results.
[0047]
Example 3
Na₂CO_Three  33.3 g is dissolved in 405 ml of water and Sr (NO_Three)₂  19.0g and TiOSO_Four・ NH₂16.8 g of O was dissolved in 415 ml of water, a precipitate was obtained in the same manner as in Example 1, and dried to obtain 18.2 g and Cs.₂O_Three  After mixing 1.82 g and calcining at 800 ° C. for 2 hours, a catalyst was prepared in the same manner as in Example 1. A perovskite structure was observed by X-ray diffraction. A transesterification reaction was carried out in the same manner as in Example 1, and the methyl ester production rate at this time was measured. Table 1 shows the results.
[0048]
Example 4
Na₂CO_Three  49.8 g is dissolved in 588 ml of water and La (NO_Three)_Three・ 6H₂O 28.15 g, Ca (NO_Three)₂・ 4H₂15.4 g of O and Cu (NO_Three)₂・ 3H₂A catalyst was prepared in the same manner as in Example 3 except that 31.4 g of O was dissolved in 474 ml of water. A perovskite structure was observed by X-ray diffraction. A transesterification reaction was carried out in the same manner as in Example 1, and the methyl ester production rate at this time was measured. Table 1 shows the results.
[0049]
Example 5
Na₂CO_Three  25.4 g is dissolved in 300 ml of water and Y (NO_Three)₂・ 6H₂9.6 g of O, Ba (NO_Three)₂  13.1 g and Co (NO_Three)₂・ 3H₂A catalyst was prepared in the same manner as in Example 3 except that 24.2 g of O was dissolved in 318 ml of water. A perovskite structure was observed by X-ray diffraction. A transesterification reaction was carried out in the same manner as in Example 1, and the methyl ester production rate at this time was measured. Table 1 shows the results.
[0050]
Example 6
Na₂CO_Three  38.2 g is dissolved in 450 ml of water and La (NO_Three)_Three・ 6H₂43.3 g of O, Sr (NO_Three)₂  21.2 g and Co (NO_Three)₂・ 6H₂A catalyst was prepared in the same manner as in Example 3 except that 29.1 g of O was dissolved in 545 ml of water. A perovskite structure was observed by X-ray diffraction. A transesterification reaction was carried out in the same manner as in Example 1, and the methyl ester production rate at this time was measured. Table 1 shows the results.
[0051]
Example 7
Na₂CO_Three  38.2 g is dissolved in 450 ml of water and La (NO_Three)_Three・ 6H₂43.3 g of O, Sr (NO_Three)₂  21.2 g and Fe (NO_Three)_Three・ 9H₂A catalyst was prepared in the same manner as in Example 3 except that 40.4 g of O was dissolved in 545 ml of water. A perovskite structure was observed by X-ray diffraction. A transesterification reaction was carried out in the same manner as in Example 1, and the methyl ester production rate at this time was measured. Table 1 shows the results.
[0052]
Comparative Examples 3 and 4
A transesterification reaction was carried out in the same manner as in Example 1 except that BaO and SrO each calcined at 800 ° C. were used as catalysts, and the methyl ester production rate at this time was measured. As a result of X-ray diffraction, it was confirmed that the catalyst was not a perovskite structure. Table 1 shows the results.
[0053]
Comparative Example 5
TiO₂  20g and Cs₂CO_Three  A transesterification reaction was carried out in the same manner as in Example 1 except that 2 g was mixed and baked at 800 ° C. to measure the methyl ester production rate. As a result of X-ray diffraction, it was confirmed that the catalyst was not a perovskite structure. Table 1 shows the results.
[0054]
[Table 1]

[0055]
Compared with the case where the said catalyst is not used by producing a methyl ester using the catalyst which consists of a composite metal oxide which has a perovskite type structure from the comparison with Examples 1-7 and Comparative Examples 1-5. It can be seen that the production rate of methyl ester is significantly improved.
[0056]
【The invention's effect】
According to the present invention, a lower alkyl ester that can be effectively used as a diesel fuel oil or the like can be produced with high efficiency and on an industrial scale from mainly fats and oils, particularly triglycerides contained in waste cooking oil.

Claims (4)

  When a lower alkyl ester is produced by performing a transesterification reaction between an oil and fat and a lower alcohol in the presence of a catalyst, a catalyst containing a composite metal oxide having a perovskite structure is used. A method for producing a lower alkyl ester.   The method according to claim 1, wherein the composite metal oxide comprises at least one selected from the group consisting of Ca, Sr and Ba.   The method according to claim 1 or 2, wherein the catalyst further comprises 1 to 10% by mass of a cesium compound in terms of mass of cesium.   The method according to any one of claims 1 to 3, wherein a transesterification reaction is carried out using a fixed bed flow type reactor filled with a solid catalyst formed by shaping the catalyst.