WO2016136692A1

WO2016136692A1 - Catalyst for producing fatty acid alkyl ester, method for producing said catalyst and method for producing fatty acid alkyl ester using said catalyst

Info

Publication number: WO2016136692A1
Application number: PCT/JP2016/055135
Authority: WO
Inventors: 研司野中
Original assignee: 日本ケッチェン株式会社
Priority date: 2015-02-25
Filing date: 2016-02-23
Publication date: 2016-09-01
Also published as: JP5832678B1; JP2016155085A; MY171534A

Abstract

Provided are a catalyst for producing a fatty acid alkyl ester, which has more excellent yield and activity stability than those of conventional ones, a method for producing the catalyst, and a method for producing a fatty acid alkyl ester using the catalyst. The catalyst contains an alumina-containing porous carrier, and at least two elements carried by the carrier and selected from group 6 of the periodic table, wherein the catalyst has an average pore diameter of 9.5-27 nm, a total pore volume of 0.5-1.0 ml/g, and a specific surface area of 120-300 m²/g. A proportion of the volume of pores having a diameter which is the average pore diameter ± 1.5 nm to the total pore volume is 15-70%, and a proportion of the volume of pores having a diameter which is the average pore diameter ± 5 nm to the total pore volume is 60% or more.

Description

Fatty acid alkyl ester production catalyst, production method thereof, and production method of fatty acid alkyl ester using the catalyst

The present invention relates to a fatty acid alkyl ester production catalyst, a production method thereof, and a production method of an aliphatic alkyl ester using the catalyst, and more specifically, esterification or transesterification reaction of a fatty acid and / or glyceride with an alcohol. The present invention relates to a catalyst for producing a fatty acid alkyl ester, a method for producing the same, and a method for producing a fatty acid alkyl ester using the catalyst.

Fatty acid alkyl esters are used as raw materials for various chemicals, resins, detergents, and surfactants. In recent years, they have been used as alternative fuels for petroleum-based fuels, especially biodiesel fuels, from the viewpoint of reducing environmental impact and carbon neutrality. The use as is expanding.
Here, the biodiesel fuel is a general term for fuels that are mainly modified by chemical treatment of vegetable oils and fats to be suitable for diesel engines.
As a typical example, fatty acid methyl ester (FAME) obtained by transesterification of a vegetable oil containing triglyceride and methanol is known.
As a method for producing a fatty acid alkyl ester, in addition to a homogeneous base catalyst method and an acid catalyst method, methods such as an enzyme method and a supercritical methanol method are known.

The base catalyst method is a method in which an oil and fat containing fatty acid glycerides and a lower alcohol such as metalanol are contacted in the presence of a base catalyst (caustic soda or the like) to obtain a fatty acid alkyl ester by a transesterification reaction. In this method, the reaction proceeds under relatively mild conditions, but when free fatty acids are present in the raw oil and fat, soap (consumption of the base catalyst) and water (inactivation of the base catalyst) are neutralized with the base catalyst. ) Is formed and the transesterification reaction is inhibited. Further, when the raw material contains a large amount of water, the saponification of the produced ester is promoted together with the base catalyst, resulting in a decrease in the ester yield.
On the other hand, although a saponification reaction does not occur with an acid catalyst (sulfuric acid or the like), water produced by an esterification reaction between an existing free fatty acid and an alcohol inactivates the acid catalyst, like a base catalyst. Furthermore, in the case of a homogeneous catalyst, it is difficult to separate the product and the catalyst, and a waste disposal facility for the catalyst solution is also required.

In addition, enzymatic method (lipase method: little waste liquid, long reaction time, expensive enzyme, unsuitable for mass production), supercritical methanol method (no catalyst and short reaction time, but high cost for small-scale facilities) ) Also had problems.

In order to cope with the above-described problems of the prior art, an ester production catalyst using a heterogeneous solid acid catalyst has been proposed. The solid acid catalyst functions as a catalyst for each of the ester exchange reaction of glyceride and the esterification reaction of free fatty acid, and has an advantage that the product after the reaction and the catalyst can be easily separated.

Patent Document 1 proposes a solid acid catalyst exhibiting a super strong acid having an argon adsorption heat of 15 to 22 kJ / mol.
However, when a super strong acid is used, the transesterification proceeds, but the catalyst is easily deactivated, and there is also a problem that a side reaction such as isomerization occurs.

Patent Document 2 discloses an esterification reaction catalyst that exhibits solid acidity with Hammett's acidity function (H ₀ ) of −3 to −9 in which molybdenum oxide is supported on a zirconia support.
However, since the main component of the support is zirconia, which is difficult to control the pore structure, most of the reaction occurs only on the outer surface of the catalyst and has a problem in reaction efficiency. Furthermore, the catalyst component is easily dissolved during the reaction process, and there is a problem in the activity stability of the catalyst.

Patent Document 3 is a group consisting of inorganic porous carriers such as silica and alumina, at least one metal element selected from Group 6 of the periodic table, and manganese, iron, cobalt, nickel, copper, zinc, gallium, and tin. A solid acid catalyst for producing a fatty acid alkyl ester is disclosed that carries at least one metal element selected from the group consisting of at least one non-metallic element of boron or silicon.
The catalyst exhibits a certain activity in transesterification and esterification reactions. However, particularly when the proportion of free fatty acids in the raw material is high, the elution of the supported active ingredient is not sufficient, and further improvement in the stability of the catalytic activity has been demanded.

International Publication No. 2004/088554 JP 2011-207820 A International Publication No. 2013/137286

An object of the present invention is to solve the problems in conventional fatty acid alkyl ester production catalysts, improve the yield of fatty acid alkyl esters, and have high stability, a method for producing the same, and fatty acid alkyl esters using the catalyst It is to provide a manufacturing method.

In view of the above-described problems of the prior art, the present inventors have conducted extensive research focusing on optimization of a support component having catalytic activity and a catalyst pore structure, and as a result, a porous support containing alumina. It was found that a catalyst having a specific amount of a specific active metal component and a specific pore structure was extremely effective for transesterification and esterification of fats and oils, and thus completed the present invention.

That is, the present invention contains a porous carrier containing alumina and at least two elements selected from Group 6 of the periodic table carried thereon, an average pore diameter of 9.5 to 27 nm, all fine particles. The pore volume is 0.5 to 1.0 ml / g, the specific surface area is 120 to 300 m ² / g, and the ratio of the pore volume with an average pore diameter of ± 1.5 nm to the total pore volume is 15 to 70% and The fatty acid alkyl ester production catalyst is characterized in that the ratio of the pore volume having an average pore diameter of ± 5 nm to the total pore volume is 60% or more.

The method for producing a fatty acid alkyl ester production catalyst of the present invention comprises a step of impregnating a porous support containing alumina with a compound solution of at least two elements selected from Group 6 of the periodic table, and then the presence of oxygen. This method includes a step of baking at 400 to 750 ° C. below.

Furthermore, the method for producing a fatty acid alkyl ester of the present invention is a method in which fatty acid and / or glyceride and alcohol are reacted at a temperature of 100 to 250 ° C. and a pressure of 0.1 to 6.0 MPa in the presence of the catalyst.

The fatty acid alkyl ester production catalyst according to the present invention is not only capable of producing a fatty acid alkyl ester stably and at a higher yield than conventional solid acid catalysts, but also glycerin produced as a by-product in the process of transesterification. It is also possible to obtain a product with high purity and high added value.

Hereinafter, the present invention will be described in detail.
(1) Carrier The alumina-containing porous carrier used for the catalyst of the present invention is based on alumina. The crystal structure of alumina in the carrier is not particularly limited. For example, alumina hydrates such as α, θ, δ, κ, η, γ, χ type transition alumina, bayerite, dibsite, boehmite, pseudoboehmite, etc. Or a mixture thereof. Alumina-containing porous carrier is an alumina hydrate powder obtained from commercially available boehmite, pseudoboehmite or the like, neutralization reaction of acidic and / or basic aluminum compounds, and alumina obtained from a sol-gel method using aluminum alkoxide as a starting material Hydrate gels and powders thereof can be obtained by kneading, molding, drying, and calcination.

The content of alumina in the carrier is preferably 75% by mass or more, particularly 80 to 100% by mass, based on the carrier and aluminum oxide.
In addition to alumina, 25 masses of silica, titania, zirconia, boria, magnesia, zinc oxide, diphosphorus pentoxide, zeolite, clay mineral, or any mixture thereof can be used for this carrier in order to modify the chemical properties of the carrier surface. % Or less, particularly preferably 1 to 20% by mass. In that case, it is preferable to add silica, titania and boria, particularly silica and boria.
In addition, there is no restriction | limiting in particular about the addition method of components other than an alumina, During the manufacturing process of the said alumina containing support | carrier, for example, it is soluble in the above component and an aqueous | water-based or non-aqueous polar solvent in an aluminum compound or an alumina hydrate. A method in which component precursors are added and finally dispersed both in the carrier skeleton and on the pore surface, and after the alumina carrier is produced, the above components and component precursors (soluble in aqueous or non-aqueous polar solvents) ) May be dispersed and supported mainly on the pore surface of alumina.

When preparing an alumina-containing support from an alumina hydrate or from a hydrate or the like to which a component other than alumina is added, the hydrate is kneaded to satisfy a desirable condition as the pore structure of the finished catalyst described later. Then, the moisture content is adjusted (55 to 70% as loss on ignition) and formed into a desired shape (pellet, sphere, extrudate, etc.).
In addition, hydrochloric acid, sulfuric acid, nitric acid, organic acids (formic acid, oxalic acid, acetic acid, citric acid, malic acid, tartaric acid, gluconic acid, etc.), ammonia, water as necessary to improve the peptization operation and moldability during kneading Sodium oxide and organic molding aids (cellulosic aids, starches, etc.) may be added. The molded product is usually 640 to 900 ° C. (instead of the ambient temperature, not the ambient temperature), preferably 660 to 890 ° C., more preferably 680 to 870 ° C. for 0.1 to 10 hours in air. Preferably, the support is calcined for 0.5 to 8 hours, more preferably 1 to 5 hours.

The carrier obtained in the above step is loaded with at least two elements selected from Group 6 of the periodic table. There are no particular limitations on the loading method, and various industrial methods such as impregnation method, coating method, spraying method and the like can be applied, but the impregnation method is preferable from the viewpoint of workability and addition efficiency.
The impregnation method, adsorption method, equilibrium adsorption method, pore filling method, incipient wetness method, evaporation to dryness method, spray method, etc. are all applicable to the present invention, but from the viewpoint of workability, the pore filling method Is preferred. The order of supporting the Group 6 elements is not particularly limited, and can be sequentially or simultaneously supported. In the case of the impregnation method, a solution in which a solvent-soluble compound of each element is dissolved in various polar organic solvents, water or a water-polar organic solvent mixture can be used, but the most preferable solvent is water.

(2) Supported component In the present invention, the Group 6 element of the periodic table supported as an active component is at least two selected from chromium, molybdenum, and tungsten. As a combination of elements to be used, chromium-molybdenum, chromium-tungsten, and molybdenum-tungsten can be used. From the viewpoint of economy and activity, a combination of molybdenum and tungsten is preferable.
The supported amount is 8 to 25% by mass, preferably 9 to 20% by mass, more preferably 10 to 18% by mass, based on the oxide catalyst, as the sum of all Group 6 group element oxides. If it is less than 8% by mass, the catalyst activity is low, and if it exceeds 25% by mass, there is no increase in activity.
Further, the range of the molar ratio of tungsten to molybdenum is 0.01 to 0.25, preferably 0.02 to 0.23, and more preferably 0.03 to 0.20. If the molar ratio is less than 0.01, the stability of the catalyst activity is lacking, and if it exceeds 0.25, no improvement in the improvement effect on the stability of the transesterification and esterification reaction is observed.

Examples of the raw material for Group 6 elements of the periodic table include chromate, molybdate, tungstate, trioxide, halide, heteropolyacid, heteropolyacid salt, and organometallic compounds including carbonyl compounds. In addition, for other reasons including reaction selectivity, active site control, and foreign matter contamination, the oxide is 0.01 to 8% by mass, preferably 0.01 to 4% by mass, more preferably, based on the oxide catalyst. Can contain 0.01 to 0.99% by mass of iron, cobalt, nickel (including any mixture thereof).

In the impregnating solution of Group 6 elements of the periodic table, ammonia water, hydrogen peroxide solution, nitric acid, sulfuric acid, hydrochloric acid, Inorganic compounds such as phosphoric acid and hydrofluoric acid, organic acids such as formic acid, oxalic acid, acetic acid, citric acid, malic acid, tartaric acid, gluconic acid, ethylenediamine, ethylenediaminetetraacetic acid, diethylenetriamine, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, etc. A chelating agent may be added.
Here, phosphoric acid can also be added as a catalyst component. In this case, the addition amount range is 0.1 to 10% by mass, preferably 0.5 to 8% by mass as phosphorous oxide based on the oxide catalyst. More preferably, it is 1 to 5% by mass. Examples of phosphoric acid that can be added include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, phosphonic acid, diphosphonic acid, phosphinic acid, and polyphosphoric acid.
In addition to adding the phosphoric acid to the group 6 element impregnation solution, it is also possible to add phosphoric acid during the production process of the alumina-containing support as described above. The above additives can be used alone or in appropriate combination.

After containing the Group 6 element of the periodic table in the alumina-containing support, a drying operation (room temperature to 300 ° C., 0.1 to 24 hours) is performed as necessary, and then a firing operation is performed. A Group 6 element is supported on an alumina-containing support in the form of an oxide.
The firing conditions at this time are 350 to 770 ° C. in air, preferably 400 to 730 ° C., more preferably 480 to 680 ° C., and 0.5 to 24 hours, preferably 1 to 12 hours.

(3) Properties of the completed catalyst In order for the completed catalyst to exhibit good catalytic performance, it is desirable to have the following physical properties and pore structure. That is, the average pore diameter is 9.5 to 27 nm, preferably 9.8 to 26 nm, more preferably 10 to 25 nm. When the average pore diameter is less than 9.5 nm, the diffusion of the raw material fats and oils into the pores becomes insufficient, and when it exceeds 27 nm, the specific surface area is reduced, so that the catalyst performance is lowered.
The total pore volume is preferably 0.5 to 1.0 ml / g, more preferably 0.6 to 0.8 ml / g. If it is less than 0.5 ml / g, it is insufficient for diffusing fats and oils into the pores. If it exceeds 1.0 ml / g, the absolute mass of the catalyst becomes light when the reactor is filled with the catalyst (catalyst Therefore, sufficient catalytic performance does not appear.

Here, as an index indicating the uniformity of the main pores contributing to the reaction, the ratio of the pore volume having an average pore diameter in the range of ± 1.5 nm is 15 to 70% with respect to the total pore volume. It is desirable to have a pore structure that is preferably 18 to 65%, more preferably 20 to 60%. If it is less than 15%, the proportion of fine pores that do not contribute to the reaction or large pores with a small surface area increases, and if it exceeds 70%, the diffusion of fats and oils having a relatively large molecular size into the pores is inhibited. It causes a decrease in activity.
Furthermore, the ratio of the pore volume in the range of the average pore diameter ± 5 nm to the total pore volume as an index indicating the shape of the distribution of the total pore diameter in the catalyst is 60% or more, preferably 65% or more, more preferably Is preferably 70% or more. If it is less than 60%, the volume ratio of micropores and giant pores that do not contribute to the reaction increases (including bimodal and multimodal pore distributions), so that the catalytic activity decreases. The pore distribution of the catalyst of the present invention is a unimodal distribution having an average pore diameter and a local maximum point in the vicinity thereof.

In addition, the pore structure (total pore volume, average pore diameter, pore distribution, etc.) of the catalyst of the present invention is the mercury intrusion method (contact angle 140 °, surface tension 480 dyn / cm), and the specific surface area is the BET method. This is the value obtained.
When measuring the pore structure and specific surface area of the finished catalyst and analyzing the composition, the catalyst was treated in air at 450 ° C. for 1 hour to remove volatile components such as moisture, and the analysis obtained here, The measured value is a value based on an oxide catalyst standard. The same heating temperature and time were applied to the measurement of loss on ignition. Further, a fluorescent X-ray analyzer was used for quantification of the supported metal component and the carrier component.

(4) Fatty acid, glyceride As the fatty acid and / or glyceride used as the raw material in the present invention, various animal and vegetable fats and oils including monoglyceride, diglyceride and triglyceride, and a mixture of fatty acids produced by hydrolysis of such animal and vegetable fats and oils can be used. .
Examples of such fat and oil mixtures include soybean oil, rapeseed oil, sunflower oil, cottonseed oil, hemp seed oil, linseed oil, tung oil, evening primrose oil, safflower oil, coconut oil, amazana oil, avocado oil, camelina oil, canola oil, coconut oil, Sesame oil, mustard oil, olive oil, corn oil, safflower oil, peanut oil, macadamia nut oil, brazil nut oil, castor oil, rice oil, jojoba oil, neem oil, palm oil, jatropha oil, carranja oil, orlanchonchi Thorium, Pseudocollistis ellipsoidia, Senedesmus, Botryococcus brownie, Euglena and vegetable oils such as algae oil obtained from these algae, beef tallow, beef bone fat, beef leg oil, pork fat, horse fat Animal oils such as sheep oil, deer oil, chicken oil, butter oil, bone oil, whale oil, shark oil, cod liver oil, sardine oil, mackerel oil, margarine, § Tsu DOO spreads, purified lard, shortening, any fat mixture of edible processed fat and oil, and more like cocoa butter and the like.
Moreover, the synthetic | combination triglyceride containing the synthetic | combination triglyceride, a monoglyceride, and / or a diglyceride, and the modified | denatured fats and oils which modified | denatured some treatments, such as oxidation and a reduction | restoration, may be sufficient. Furthermore, the used waste oil of the above fats and oils, the arbitrary mixtures of waste oil and the said fats and oils can also be used.

(5) Alcohol The alcohol used in the method for producing a fatty acid alkyl ester of the present invention is preferably an alcohol having 1 to 10 carbon atoms.
Such alcohols include primary alcohols such as methanol, ethanol, n-propyl alcohol, isobutyl alcohol, n-butyl alcohol, pentyl alcohol and neopentyl alcohol, and secondary alcohols such as isopropyl alcohol and sec-butyl alcohol. , Tertiary alcohols such as tert-butyl alcohol and tert-amyl alcohol, polyhydric alcohols such as ethylene glycol, propylene glycol and trimethylene glycol, and any mixture of these alcohols, but primary alcohols are preferred. . In particular, when the produced fatty acid alkyl ester is used as an alternative fuel such as biodiesel fuel, methanol or ethanol is preferable.

(6) Production Conditions for Fatty Acid Alkyl Ester In the present invention, the starting fatty acid and / or glyceride and alcohol are heated at a temperature of 100 to 250 ° C, preferably 120 to 230 ° C, more preferably 140 to 210 ° C, and a pressure of 0.1. It is contacted with the catalyst of the present invention at a pressure of ˜6.0 MPa, preferably 0.5-5 MPa, particularly preferably 1.0-4.5 MPa.
There is no restriction | limiting in particular in the reactor to be used, Either a batch type or a flow-through type reactor is applicable. The reaction time is not limited, and is 0.1 to 100 hours in the case of a batch system, and 0 to 0 in the flow system when the time for contacting the raw oil and fat and alcohol with the catalyst of the present invention is expressed as a mass space velocity (WHSV). Conditions of 0.1 to 3 h ⁻¹ , preferably 0.2 to 2 h ⁻¹ can be applied.

In addition, although it is about the usage-ratio of a raw material and alcohol, in the esterification reaction of a fatty acid, 1 mol of alcohol is needed with respect to 1 mol of fatty acid.
In the case of transesterification, if the starting ester is triglyceride, it is necessary to react 3 mol of alcohol with 1 mol of triglyceride. Since both esterification and transesterification reactions are reversible equilibrium reactions, an operation such as excessive use of alcohol as a reactant or removal of a product from the reaction system is effective for advancing the positive reaction.
In the present invention, paying attention to the fatty acid in the raw material (in the case of glyceride, the site derived from the ester bond fatty acid), the molar ratio of alcohol to fatty acid is 1.1 to 50, preferably 1.2 to 40, more preferably. Raw oils and fats and alcohols can be used at 1.5 to 30, particularly preferably 3 to 15.

In the production of the fatty acid alkyl ester according to the present invention, the above reaction may be carried out in one stage, but it is also possible to carry out the reaction in a plurality of stages of two or more stages in order to increase the purity of the produced ester.
When the reaction is carried out in two or more stages, either a batch type or a flow type reactor can be used, but a flow type reactor is preferably used from the viewpoint of reaction efficiency. In that case, after performing the 1st step | paragraph reaction on the said conditions, alcohol, glycerol, and water are removed from a product, and the crude fatty-acid alkylester (A) containing an unreacted fat and free fatty acid is obtained. Here, alcohol and water can be separated by simple distillation, rectification or the like under normal pressure or reduced pressure conditions. For glycerin, various methods such as sedimentation separation, centrifugal separation, electrostatic separation and the like utilizing the specific gravity difference and polarity difference with the fatty acid alkyl ester can be applied.

The crude fatty acid alkyl ester (A) thus obtained is reacted in the second stage with alcohol at the same pressure, raw material / alcohol ratio, and mass space velocity as in the first stage. The reaction temperature at this time is 80 to 230 ° C., preferably 60 to 210 ° C., and is preferably equal to or lower than the first stage.
Thereby, side reactions, such as the hydrolysis reaction of produced | generated ester and the etherification reaction between glycerol and alcohol, can be suppressed.
After the second stage reaction, alcohol, water and glycerin are removed by the same method as in the first stage to obtain a crude fatty acid alkyl ester (B). The crude fatty acid alkyl ester (B) is distilled under normal pressure or reduced pressure, and a fraction having boiling points of 100 ° C. or lower and 360 ° C. or higher is removed to obtain a purified fatty acid alkyl ester.
This purified fatty acid alkyl ester can be used as it is as various chemical raw materials and biodiesel fuel, but a higher quality fatty acid alkyl ester can be obtained by further rectifying under normal pressure or reduced pressure.

The following examples further illustrate the present invention. However, the following examples do not limit the present invention.
(Preparation of catalyst)

A silica-alumina hydrate gel (silica / alumina mass ratio: 1.5 / 98.5) is prepared by adding and mixing aluminum sulfate, sodium aluminate and water glass into a tank containing hot tap water. did. The hydrate gel was separated from the solution, and the impurities were washed and removed using warm water, citric acid was added, and the mixture was heated and kneaded using a kneader to adjust the moisture content to 64.3%.
This kneaded product was extruded and calcined in air at 850 ° C. for 1.5 hours to obtain a silica-alumina carrier.
Prepare an impregnating solution by dissolving ammonia water, ammonium molybdate, and ammonium metatungstate in distilled water so that it becomes 8.7% by mass of molybdenum trioxide and 1.3% by mass of tungsten trioxide based on oxide catalyst. After impregnating the silica-alumina support, the impregnated support was dried at 120 ° C. for 2 hours and then calcined in air at 500 ° C. for 6 hours to obtain Catalyst A.
Table 1 shows the physical properties and chemical composition of Catalyst A.

Example 1 was the same as Example 1 except that water glass was not used at the time of carrier preparation, the moisture content at the time of molding the alumina hydrate was 62.8%, and the carrier calcination temperature was 800 ° C. Catalyst B was prepared by the method.
Table 1 shows the physical properties and chemical composition of Catalyst B.

(Comparative Example 1)
With reference to Example 8 (Catalyst H) of Patent Document 3, the alumina support of Example 2 of the present application was impregnated with an ethyl silicate / ethanol solution and dried at 120 ° C. to prepare an alumina support on which ethyl silicate was supported. (Silica / alumina mass ratio: 1.5 / 98.5).
On the other hand, molybdic acid was 8.7% by mass of molybdenum trioxide (10% with respect to alumina) and 3.9% by mass of tin dioxide (4.5% with respect to alumina) based on the oxide catalyst. Prepare an impregnating solution in which ammonium and tin (IV) chloride are dissolved in distilled water, impregnate the above-mentioned ethyl silicate-supported alumina support, dry the impregnated support at 120 ° C. for 2 hours, and calcinate in air at 500 ° C. for 6 hours. Thus, catalyst C was obtained.
The physical properties and chemical composition of the catalyst C are shown in Table 1.

[Synthesis test of fatty acid alkyl ester]
Fatty acid methyl esters (FAME) were synthesized from raw oils and fats using the catalysts A to C of Example 1, Example 2 and Comparative Example 1 using an autoclave (content volume 120 ml). Table 2 shows the reaction conditions during the synthesis.

After the reaction, the product was taken out from the autoclave, the catalyst was removed by solid-liquid separation, methanol was distilled off by an evaporator, and FAME and glycerin were separated by stationary separation.
The FAME layer was subjected to gas chromatography and acid value measurement to determine the triglyceride conversion rate and FAME acid value. The purity of glycerin produced as a byproduct was also determined by gas chromatography.
The above measurement results are shown in Table 3.

From the results of Table 3, when catalyst A and catalyst B of the present invention were used, the triglyceride conversion rate was high, and the FAME acid value was low. From this, it can be seen that when the catalyst of the present invention is used, the amount of free fatty acid in the produced ester is small and the transesterification and esterification reaction proceed efficiently.
On the other hand, in the catalyst C of Comparative Example 1, the conversion rate of triglyceride is low and the acid value of FAME is high. On the other hand, it is conceivable that the free fatty acid in the raw fat / oil is not sufficiently esterified, or the fatty acid produced by hydrolysis of the produced FAME increases the acid value.

Here, looking at the purity of glycerin as a by-product, the purity of the catalyst C of Comparative Example 1 is low. As impurities in glycerin, dehydration condensation products with metal rule such as 2-methoxy-1,3-propanediol and 3-methoxy-1,2-propanediol were observed. It is considered to have been higher than necessary, and showed a catalytic action for side reactions such as etherification between glycerol and methanol and hydrolysis of FAME.
On the other hand, it can be seen that the purity of glycerin in the catalysts A and B of Examples 1 and 2 is high, and the catalyst of the present invention is excellent in the quality of by-products.

[Elution test of catalyst component with acid]
A test for evaluating the stability of the catalyst was conducted by forcibly eluting the catalyst components by immersing the catalysts A, B, and C in a 5% oxalic acid aqueous solution.
The catalyst sample was weighed after heating in a muffle furnace at 450 ° C. for 1.5 hours, and an elution test was performed under the following conditions. Thereafter, the catalyst sample was washed with distilled water, heated at 450 ° C. for 1.5 hours in a muffle furnace, the catalyst sample was weighed, and the elution ratio (mass reduction rate) of the catalyst component was determined from the mass difference before and after the elution test. .
Test conditions and test results are as shown in Tables 4 and 5 below.

From the results of Table 5, the catalyst of the present invention has less acid elution of the supported metal component than the catalyst C of the prior art, and therefore the degree of activity deactivation is low even when using a raw material having an acid property with many free fatty acids. It is thought that the effect which was excellent in activity stability is shown.

INDUSTRIAL APPLICABILITY The present invention can produce fatty acid alkyl esters that can be used for various chemicals, resins, detergents, surfactant raw materials, biodiesel fuel, and the like from various oil and fat raw materials including poor waste oil with high efficiency and low cost. Useful as technology.
Further, the purity of glycerin produced as a by-product is high, and it is possible to obtain a product with high added value including the product of the main reaction.

Claims

A porous carrier containing alumina and at least two elements selected from Group 6 of the periodic table supported thereon, an average pore diameter of 9.5 to 27 nm, and a total pore volume of 0.5. 5 to 1.0 ml / g, specific surface area of 120 to 300 m 2 / g, ratio of pore volume of average pore diameter ± 1.5 nm to total pore volume is 15 to 70%, and total pores A fatty acid alkyl ester production catalyst in which the ratio of the pore volume having an average pore diameter of ± 5 nm to the volume is 60% or more.
2. The fatty acid alkyl ester production catalyst according to claim 1, wherein the total supported amount of Group 6 elements in the periodic table in the catalyst is 8 to 25% by mass in terms of oxide.
3. The fatty acid alkyl ester production catalyst according to claim 1, wherein the elements selected from Group 6 of the periodic table are molybdenum and tungsten.
The fatty acid alkyl ester production catalyst according to any one of claims 1 to 3, wherein a molar ratio of tungsten to molybdenum is 0.01 to 0.25.
Impregnating a porous support containing alumina with a compound solution of at least two elements selected from Group 6 elements of the periodic table, and thereafter baking at 400 to 750 ° C. in the presence of oxygen. The method for producing a fatty acid alkyl ester production catalyst according to any one of claims 1 to 4, characterized in that:
A fatty acid characterized by reacting a fatty acid and / or a glyceride with an alcohol at a temperature of 100 to 250 ° C and a pressure of 0.1 to 6.0 MPa in the presence of the catalyst according to any one of claims 1 to 4. A method for producing an alkyl ester.