JP2007176973A - Method for producing fatty acid lower alkyl ester for gas oil substitute fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which a high-purity fatty acid lower alkyl ester suitably usable as a gas oil substitute fuel is stably produced from a raw material containing an animal or vegetable oil and fat in high yield. <P>SOLUTION: The method for producing the fatty acid lower alkyl ester comprises the following steps: (A) an esterification step of esterifying a fatty acid in the raw material with a lower alkyl alcohol using a cation exchange resin and affording a reaction mixture containing an ester mixed oil having ≤2 acid value; (B) a transesterification step having a first step of carrying out transesterification of an oil and fat in the ester mixed oil with the lower alkyl alcohol while regulating the amount of an alkali catalyst according to the acid value; (R) a recycling step of carrying out acid decomposition of a soap formed as a by-product in the step (B) under conditions of pH2-5, affording a fatty acid and returning the fatty acid; and (C) a distillation step having a vacuum distillation step of distilling the fatty acid lower alkyl ester from the oily phase obtained in the transesterification step (B). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a fatty acid lower alkyl ester that is suitably used as a light oil substitute fuel.

In recent years, biomass fuel using organic matter derived from animals and plants as an energy source has attracted attention as an alternative to light oil. Diesel oil is a kind of petroleum product and refers to the portion that is distilled between dredged oil and heavy oil during the distillation of crude oil, and has a boiling range of about 250-400 ° C ("Chemical Dictionary" Kyoritsu Publishing Co., Ltd., (The 26th edition was issued on October 15, 1981).
As one of the biomass fuels, there is a fatty acid lower alkyl ester obtained by transesterifying natural fats and oils with a lower alkyl alcohol such as methanol. For example, Patent Documents 1 and 2 disclose a method for producing a fatty acid lower alkyl ester. It is disclosed.
JP 59-5142 A Japanese Patent No. 3046999

  However, fatty acid lower alkyl esters obtained by such conventional production methods cannot always satisfy the EU standard for light oil alternative fuels in which the content of various components and the like are determined, and often cannot be used as light oil alternative fuels. It was. If a fuel that deviates from the EU standard is used as a light oil alternative fuel, problems such as clogging of the fuel supply line and the fuel injection nozzle occur. Further, the conventional method for producing a fatty acid lower alkyl ester has a problem in that the production yield is low and the yield of the fatty acid lower alkyl ester relative to the raw material is insufficient.

  This invention is made | formed in view of the said situation, and makes it a subject to produce stably the high purity fatty-acid lower alkyl ester which can be used conveniently as a light oil alternative fuel with a high yield.

The method for producing a fatty acid lower alkyl ester of the present invention is a method for producing a fatty acid lower alkyl ester for gas oil alternative fuel from a raw material containing animal and vegetable oils and fats, and using a cation exchange resin, the fatty acid in the raw material is Esterification step (A) for obtaining a reaction mixture containing an ester mixed oil having an acid value of 2 or less by esterification with a lower alkyl alcohol, and the amount of the alkali catalyst is 0.1 to 1 with respect to 100 parts by mass of the ester mixed oil. Transesterification step (B) comprising at least a first step of transesterifying the fats and oils in the ester mixed oil with lower alkyl alcohol while adjusting according to the acid value within the range of parts by mass; The soap produced as a by-product in the transesterification reaction step (B) is decomposed with an acid under the conditions of pH 2 to 5 to produce a fatty acid, and the fatty acid is converted into the esterification step ( ) Or a recycle step (R) to be returned to the step preceding the esterification step (A) and a reduced pressure for distilling the fatty acid lower alkyl ester from the oil phase obtained in the transesterification step (B). A distillation step (C) having at least a distillation step.
When the animal and vegetable fats and oils are unrefined fats and oils, it is preferable to have a degumming step (P) for removing gum from the unrefined fats and oils on the front side of the esterification step (A).
It is preferable that the said degumming process (P) is a process which mixes the modifier | denaturant which consists of phosphoric acid with the said unrefined fats and oils, and the adsorption agent which consists of pearlite, and filters the obtained mixture.
The transesterification step (B) is preferably composed of two steps.
It is preferable that sodium hydroxide is used as the alkali catalyst and sulfuric acid is used as the acid to produce sodium sulfate as a by-product in the recycling step (R).
The distillation step (C) preferably has two or more vacuum distillation steps in which the number of carbon atoms of the fatty acid lower alkyl ester to be distilled is different.
When the main component of the animal and vegetable oils and fats is oils and fats derived from fatty acids having 16 and / or 18 carbon atoms, the glyceride content in the distillate distilled in the last step of the vacuum distillation step is 0. It is preferable to set the distillation conditions in the last step so as to satisfy the following (i) to (iii) so as to be 1% by mass or less.
(I) The top pressure of the distillation column is 0.1 to 1 kPa, and the bottom pressure is 2 to 5 kPa. (Ii) The top temperature of the distillation column is 150 to 200 ° C, and the bottom temperature is 190 to 220 ° C.
(Iii) The reflux ratio is 0 to 1, and the evaporation rate is 95 to 99%.

  ADVANTAGE OF THE INVENTION According to this invention, the high purity fatty-acid lower alkyl ester which can be used conveniently as a light oil alternative fuel can be manufactured stably with a high yield.

Hereinafter, the present invention will be described in detail.
Animal and vegetable fats and oils used as raw materials in the production method of the present invention are derived from animals (including microorganisms) and plants, and are mainly composed of fats and oils (fatty acid triglycerides). Examples of animal-derived materials include beef tallow and pork fat. Examples of plant-derived materials include palm oil, palm kernel oil, palm oil, rapeseed oil, soybean oil, sunflower oil, and corn oil. These animal and vegetable oils and fats are unrefined unrefined fats and oils that contain gums mainly composed of phospholipids, free fatty acids (hereinafter sometimes referred to as free fatty acids), and odor components. Alternatively, it may be a refined fat or oil from which at least a part of these has been removed by a refining treatment. Hereinafter, the main component refers to a component occupying at least 50%.

  Moreover, animal and vegetable fats and oils may be used individually by 1 type, or may mix and use 2 or more types. Furthermore, you may mix and use the fatty acid collect | recovered in manufacturing processes, such as another substance, for animal and vegetable fats and oils, for example. When there are too many such fatty acids, there may be an adverse effect on each step, so 5 parts by mass or less is preferable with respect to 100 parts by mass of animal and vegetable fats and oils.

  As unrefined fats and oils, for example, crude palm can be suitably used. Crude palm oil is obtained by squeezing the fruit pulp of oil palm, and is an unpurified mixture mainly composed of fatty acids of 16 to 18 carbon atoms. In addition, the crude palm oil includes gums such as carotene, phospholipids, proteins, and resinous substances, free fatty acids, and oils and fats of fatty acids having 20 carbon atoms. As the crude palm oil, those having a free fatty acid content of 5% by mass or less and a peroxide value of 5 m equivalent / kg or less are particularly preferable.

FIG. 1 is a schematic process diagram showing an example of the production method of the present invention, and shows a case where crude palm oil, which is an unrefined fat, is used as a raw animal and vegetable fat.
When using unrefined fats and oils such as crude palm oil, first, after degumming step (P), esterification step (A) of fatty acid in the raw material is performed, and then transesterification step ( B) and the distillation step (C) are carried out. When using refined fats and oils, an esterification process (A) can be performed without performing a degumming process (P). In the recycling step (R), the soap produced as a by-product in the transesterification step (B) is decomposed with an acid to form a fatty acid, and this fatty acid is reused. FIG. 2 shows an example of the recycling process (R).

[Degumming step (P)]
The degumming step (P) is a step for previously removing insoluble matters such as gum and colloidal impurities mainly composed of phospholipids contained in unrefined fats and oils when unrefined fats and oils are used as raw materials. And after implementing this process, esterification process (A) is performed.
There is no particular limitation on the specific method of the degumming step (P), and it may be a method of mixing the adsorbent with unrefined oil and fat together with warm water, and then filtering the resulting mixture to remove insoluble matter. As shown in the figure, a method of adding phosphoric acid as a modifier to an unrefined oil and fat and adding an adsorbent and filtering is preferable. When phosphoric acid is used, the degumming rate is increased, and by-products are easily separated in each subsequent step, so that the separation efficiency is improved. As a result, a high-purity fatty acid lower alkyl ester can be obtained in a high yield. As the adsorbent, pearlite, diatomaceous earth, activated clay and the like can be used, but diatomaceous earth and pearlite are preferable, and pearlite is more preferable because it has higher adsorption ability. Note that pearlite is a foam formed by heat treating obsidian at a high temperature.

  Specifically, the unrefined fat / oil is preferably heated to 50 to 70 ° C., more preferably 60 to 70 ° C., and phosphoric acid and pearlite are added thereto, preferably 1 to 60 minutes, more preferably 10 to 10 minutes. Mix and stir for 40 minutes. After mixing and stirring, the mixture is filtered with a filter equipped with a filter such as a cloth filter to remove insoluble matters, and a degummed product is obtained as a filtrate. When the treatment temperature is 50 to 70 ° C., useful components in the unrefined fats and oils are not altered or deteriorated and can be effectively degummed.

  Here, the addition amount of phosphoric acid is preferably 0.01 to 0.1 parts by mass with respect to 100 parts by mass of unrefined fats and oils. When the amount is 0.01 parts by mass or more, degumming effectively proceeds. On the other hand, when the amount is 0.1 parts by mass or less, phosphoric acid that did not contribute to degumming hardly remains and is derived from the residual phosphoric acid. The production of insoluble salts in the transesterification step (B) to be carried out tends to be suppressed. Moreover, it is more preferable to adjust suitably the addition amount of phosphoric acid according to the gum content of unrefined fats and oils. The gum content is A. O. C. It can be measured by S test method Ca 9f-57.

Moreover, it is preferable that phosphoric acid is added with the form of aqueous solution, In that case, the phosphoric acid concentration of phosphoric acid aqueous solution has preferable 70 mass% or more, More preferably, it is 75-90 mass%. Such a concentration is preferable because water as a solvent is less likely to adversely affect the subsequent process than the degumming process (P) and the filterability of the gum is deteriorated.
The amount of pearlite added is preferably 0.03 to 0.15 parts by mass, more preferably 0.03 to 0.1 parts by mass, and still more preferably 0.03 to 0.15 parts by mass with respect to 100 parts by mass of the unrefined fats and oils. 0.05 parts by mass. When it is 0.03 parts by mass or more, degumming effectively proceeds, while when it is 0.15 parts by mass or less, loss of unrefined fats and oils can be suppressed and the amount of pearlite to be discarded can be reduced.

  In the degumming step (P), unrefined fats and oils containing a large amount of adsorbent may be circulated and supplied to the filter to form a precoat phase on the surface of the filter so that the filtration can be performed more smoothly. In this case, the amount of pearlite added is preferably 0.2 to 1.0 parts by mass, more preferably 0.2 to 0.7 parts by mass, and still more preferably 0.2 to 100 parts by mass of the unrefined fat. It is -0.4 mass part. Even in this case, when the added amount of pearlite is within such a range, it is possible to effectively degumming while suppressing the loss of unrefined oil and fat and reducing the amount of pearlite to be discarded.

  In addition, before and after the degumming step (P) and during the degumming step (P), it is preferable to remove impurities from the unrefined fat as necessary. Contaminants may be removed by the same method and the same apparatus as the gum removal, or may be removed by a method such as stationary separation in an unrefined oil storage tank, a filtration device, or centrifugation. Contaminants include soil, gravel, and garbage, and in some cases, metal may be included. Moreover, it is preferable that the moisture content of the degummed product is 2000 ppm or less, and when exceeding this, it is preferable to remove a water | moisture content suitably here. This is because a large amount of moisture may adversely affect the transesterification rate in the subsequent transesterification step (B).

[Esterification step (A)]
The esterification step (A) is a step of obtaining a reaction mixture containing an ester mixed oil by esterifying a fatty acid in a raw material with a lower alkyl alcohol using a cation exchange resin.
Here, the reaction mixture is an untreated mixture obtained in the esterification step (A), and the ester produced in the esterification step (A), the fat and oil as the main component of the raw material, In addition to the ester mixed oil composed of other components originally contained in the raw material, it refers to one containing unreacted lower alkyl alcohol and by-product water. That is, an ester mixed oil is obtained by removing lower alkyl alcohol and moisture from the reaction mixture which is an untreated mixture obtained in the esterification step (A).

  The fatty acids include free fatty acids originally contained in the raw materials and recovered fatty acids that are by-produced in the transesterification step (B) and recovered and returned in the recycling step (R), both of which are esterified here. It becomes a target.

  Moreover, it is preferable from the point of the transesterification rate in the transesterification reaction process (B) that the water content of the raw material provided to an esterification process (A) is 2000 ppm or less. When the raw material contains unrefined fat and oil and has already been subjected to the degumming step (P), the moisture content is reduced to 2000 ppm or less in the degumming step (P) as described above. It is preferable. When using refined fats and oils as raw materials, many of the water content has already been reduced to 2000 ppm or less, but in the case of more than 2000 ppm, other refined fats and oils with less water content are mixed. For example, it is preferable to reduce the water content to such a level.

In the esterification step (A), esterification is performed so that the acid value of the ester mixed oil is 2 or less, preferably 1 or less, more preferably 0.1 to 0.5. The lower the acid value of the ester mixed oil reached in the esterification step (A), the better, but the practical lower limit is about 0.1. In order to set the acid value to 2 or less, conditions such as column type, column temperature, column residence time, and the amount of lower alkyl alcohol used may be adjusted.
Performing such esterification step (A) before the transesterification step (B) is very important when the finally obtained fatty acid lower alkyl ester is used as a light oil alternative fuel.

That is, when the ester mixed oil contains a fatty acid whose acid value exceeds 2, the alkali catalyst used in the transesterification step (B) is consumed by the fatty acid, and the intended transesterification proceeds. Not only will not, but a large amount of soap will be by-produced. Nevertheless, if transesterification is to proceed, a large amount of alkali catalyst is required, saponification of fats and oils proceeds, and the amount of soap produced increases further. By-products such as soap are thought to cause clogging of the fuel supply line and fuel injection nozzle. If the amount is large, the separation work and production yield will be adversely affected and the load on the recycling process (R) Is also undesirable.
Therefore, in the esterification step (A), a high-purity fatty acid lower alkyl ester in which clogging when used as a light oil alternative fuel is suppressed by pre-esterifying the fatty acid so that the acid value is 2 or less. However, it can be obtained smoothly at a high yield.

The acid value is the concentration of the acidic substance expressed by the mass (mg) of potassium hydroxide required for neutralization per 1 g of the sample, and in the case of fats and oils, it means the concentration of fatty acids. An acid value of 1 corresponds to a fatty acid concentration of 0.46% by mass (in terms of palmitic acid). The acid value is sometimes called AV.
In actual measurement, the reaction mixture was sucked with an evaporator to remove unreacted lower alkyl alcohol and water to obtain an ester mixed oil, which was further pretreated by passing it through a filter paper containing anhydrous sodium sulfate. Thereafter, a neutralization titration method is preferred.

  Furthermore, since such an esterification step (A) is not to remove fatty acids out of the system but to convert them into fatty acid lower alkyl esters, the raw material-based production yield can be kept high. Moreover, such esterification step (A) is performed before the transesterification step (B), and when the degumming step (P) is performed, the degumming step (P) and the transesterification reaction are performed. Since it is performed continuously between step (B), it is very efficient. A method of maintaining the production yield by esterifying the fatty acid removed outside the system in another line and then mixing it with the finally obtained fatty acid lower alkyl ester can be considered, but such a method is efficient. Not right.

  In the esterification step (A), water is produced together with the lower alkyl ester of fatty acid. Therefore, if a large amount of fatty acid is contained in the raw material, the amount of water produced by the esterification is increased accordingly. The presence of a large amount of water may adversely affect the transesterification rate in the transesterification step (B) to be carried out. Therefore, the amount of fatty acid in the raw material to be treated in the esterification step (A) is preferably 15 or less, more preferably 12 or less, and further preferably 10 or less as an acid value. If the acid value of the raw material is 15 or less, in the esterification step (B), when the raw material is esterified so that the acid value of the ester mixed oil is 2 or less, the amount of water generated along with the esterification Does not become excessive, and the water content in the reaction mixture tends to be suppressed to 5000 ppm or less. With such a water content, even if this is subjected to the transesterification step (B) without separating the water from the reaction mixture, the water does not greatly affect the transesterification rate. The acid value of the raw material referred to here includes not only the acid value derived from free fatty acids but also the acid value derived from recovered fatty acids.

  Further, in the esterification step (A) in the present invention, esterification is performed using a cation exchange resin. Therefore, in addition to the simple method of bringing the raw material into contact with the cation exchange resin, the esterification can proceed continuously, and other esterification methods such as a method using a solid catalyst and a method of adding an acid such as sulfuric acid. Compared to the above, a high esterification reaction rate can be achieved. In addition, the method of adding an acid has problems such as deterioration of quality of animal and vegetable fats and oils as raw materials and corrosion of the apparatus, but such a problem does not occur in a method using a cation exchange resin.

Furthermore, examples of the cation exchange resin include an acid type solid cation exchange resin and an acid gel type cation exchange resin. Particularly, the use of an acid gel type cation exchange resin is preferable because the esterification reaction rate is further increased. The reason for this is not clear, but can be inferred as follows. In other words, the catalytic activity of acid-type solid cation exchange resins decreases due to adhesion or adsorption of water generated by the esterification reaction, but water can be taken up as hydrated water in acidic gel cation exchange resins. This is considered to be because the catalytic ability is not lowered by water.
The degree of crosslinking of the acidic gel type cation exchange resin is preferably in the range of 3 to 10%. If it is 3% or more, it is preferable at the point of resin strength, and if it is 10% or less, it is preferable from the point of the removal efficiency of a fatty acid. The degree of crosslinking is more preferably 4-8%. Of these, those having a degree of crosslinking of 4% are particularly preferred because the esterification reaction rate of fatty acids is the highest and the mechanical strength of the resin is sufficient.

  Examples of the acid gel type cation exchange resin that can be suitably used include sulfonated styrene-divinylbenzene copolymer, for example, Diaion SK104 (trade name, degree of crosslinking 4%) manufactured by Mitsubishi Chemical Corporation, SK106 (Trade name, crosslinking degree 6%), SK 1B (trade name, crosslinking degree 6%) and SK110 (trade name, crosslinking degree 10%) and Dowex (trade name, crosslinking degree 4%) ), Amberlite (trade name, degree of crosslinking: 4%) manufactured by Rohm and Haas.

As a specific method of the esterification step (A), there is a method in which a column filled with a cation exchange resin is prepared, and a mixture of a lower alkyl alcohol and a raw material is supplied to the column and allowed to pass through.
The conditions for passing through the column are such that the column temperature is preferably 40 to 70 ° C., more preferably 50 to 65 ° C., still more preferably 60 to 65 ° C., and the column residence time is preferably 60 to 480 minutes, more preferably It is 90 to 360 minutes, more preferably 90 to 240 minutes. When the temperature and the column residence time are such, the flowability of the mixture is good, the reaction rate is sufficient, and the column does not need to be excessively large or pressure-resistant, which is efficient.

  Before supplying the mixture of the lower alkyl alcohol and the raw material to the column, it is preferable to wash the cation exchange resin with alcohol as a pretreatment. As the alcohol for washing, it is preferable to use the same lower alkyl alcohol as that used for the esterification reaction. Such washing is preferably performed until the moisture in the alcohol before and after passing through the column does not change. By washing in this way, the water in the cation exchange resin is replaced with alcohol, and the esterification efficiency of the fatty acid can be further increased. Specifically, it is preferable to wash with 2 to 5 times the volume of cation exchange resin alcohol.

As the lower alkyl alcohol, an alcohol having 4 or less carbon atoms can be used, and specific examples include methanol, ethanol, propanol, butanol and the like. These may be used alone or in combination of two or more, but preferably methanol is used as shown.
Moreover, although the addition amount of a lower alkyl alcohol is suitably determined according to the fatty acid distribution in a raw material, Preferably it is 5-50 mass parts with respect to 100 mass parts of raw materials, More preferably, 10-30 mass parts More preferably, it is 15 to 25 parts by mass. Within such a range, a sufficient esterification reaction rate can be obtained, and an excessive increase in the recovery cost and equipment capacity of the lower alkyl alcohol can be suppressed.
Further, the lower the amount of water in the lower alkyl alcohol, the better. However, in practice, it is preferably 1500 ppm or less, more preferably 1000 ppm or less, and even more preferably 600 ppm or less.

[Transesterification step (B)]
After such esterification step (A), an ester exchange reaction step (B) is carried out in which the fat or oil in the ester mixed oil is transesterified with a lower alkyl alcohol using an alkali catalyst. Here, the fats and oils to be transesterified are present as the main components of the raw animal and vegetable fats and oils. This transesterification produces fatty acid lower alkyl ester and glycerin.

  Alkali catalysts are preferable because high-quality fatty acid lower alkyl esters are easily obtained at low temperatures, and specific examples include sodium hydroxide, potassium hydroxide, sodium methylate and the like. One or more of these can be used, but sodium hydroxide and potassium hydroxide are preferable from the viewpoint of cost, and sodium hydroxide is preferable as shown in the figure from the viewpoint of operability.

Further, this transesterification step (B) comprises at least one step, and in the first step, the amount of the alkali catalyst according to the acid value of the ester mixed oil obtained in the esterification step (A). The transesterification reaction is carried out while controlling.
That is, when the amount of the alkali catalyst is large, the reactivity of the transesterification reaction is increased. However, if the amount of alkali catalyst is large, the amount of soap produced as a by-product due to the reaction of the alkali catalyst with fatty acids and fats and oils also increases, which adversely affects the soap separation work, production yield, and the purity of the fatty acid lower alkyl ester obtained. And the load of the recycling process (R) described later increases. Therefore, it is important to allow the transesterification to proceed efficiently while suppressing the amount of soap produced as a by-product. To that end, pay attention to the acid value of the ester mixed oil and control the amount of alkali catalyst accordingly. However, it is preferred to carry out the transesterification reaction.

Specifically, with respect to 100 parts by mass of the ester mixed oil, the acid value is within the range of 0.1 to 1.0 parts by mass of the alkali catalyst, more preferably within the range of 0.2 to 0.6 parts by mass. It is preferable to increase the amount of alkali catalyst when the acid value is large and to decrease the amount of alkali catalyst when the acid value is small. More preferably, sodium hydroxide alone is used as the alkali catalyst, and the catalyst amount C _NaOH [parts by mass] with respect to 100 parts by mass of the ester mixed oil at that time is determined by the following formula (1) using the acid value as a parameter. . The following formula (1) is obtained by experiment.
C _NaOH = 0.2 + 0.07 × AV (1) However, AV indicates an acid value and is 2 or less.

When potassium hydroxide is used alone as the alkali catalyst, the catalyst amount C _KOH [parts by mass] with respect to 100 parts by mass of the ester mixed oil is determined by the following formula (2) using the acid value as a parameter. It is preferable to do. The following formula (2) is obtained by experiment.
C _KOH = 0.37 + 0.1 × AV (2) However, AV indicates an acid value and is 2 or less.

  As a specific method of the transesterification reaction step (B), a lower alkyl alcohol and an alkali catalyst are added to the reaction mixture obtained in the esterification step (A), and the reaction proceeds under the conditions described later. Good. The reaction mixture contains water, but when the water content is 5000 ppm or less, it is particularly effective to use the above-mentioned alkali catalyst amount.

As the lower alkyl alcohol to be used, those exemplified in the above-mentioned esterification step (B) can be used similarly, and methanol is preferably used as shown in the figure.
The amount of the lower alkyl alcohol used (including the amount of the lower alkyl alcohol contained in the reaction mixture) is preferably 10 to 50 parts by weight, more preferably 20 to 40 parts by weight per 100 parts by weight of the ester mixed oil. Part, more preferably 30 to 40 parts by weight. Within such a range, it is not necessary to enlarge the apparatus to be used, and the lower alkyl alcohol can be recovered and purified at low cost, and a sufficient transesterification rate can be obtained.

  Moreover, reaction temperature becomes like this. Preferably it is 40-120 degreeC, More preferably, it is 50-100 degreeC, More preferably, it is 60-80 degreeC. Within such a range, the speed of the transesterification reaction is sufficient, and it is not necessary to increase the pressure resistance of the apparatus to be used, which is efficient. Moreover, processing time becomes like this. Preferably it is 15 to 120 minutes, More preferably, it is 30 to 70 minutes, More preferably, it is 40 to 60 minutes. Within such a range, a high transesterification rate can be achieved without increasing the size of the apparatus used.

By such a first step, an oil phase mainly composed of fatty acid lower alkyl ester and a phase mainly composed of glycerin (hereinafter referred to as glycerin phase) are generated.
The oil phase thus obtained may be subjected to the distillation step (C) as it is, but preferably, after the second step transesterification step is carried out following such a first step, the distillation step ( C) is preferably carried out. Thus, by making transesterification into two steps, the transesterification rate of fatty acid lower alkyl ester can be increased. Preferably, the reaction is carried out in two stages in which the reaction rate is advanced to about 95 to 96% in the first step and the reaction rate is advanced to about 99% in the second step.

After the first stage, an oil phase mainly composed of a fatty acid lower alkyl ester and a glycerin phase are separated, and only the oil phase is supplied to the second stage.
Separation of the oil phase and the glycerin phase may be performed by stationary separation, centrifugation, or the like. In the case of stationary separation, the temperature is preferably 30 to 70 ° C., more preferably 30 to 50 ° C. The time is preferably 30 to 90 minutes, more preferably 30 to 60 minutes. Under such conditions, the fluidity of the oil phase is good and the vapor pressure of the lower alkyl alcohol can be suppressed, so that it is not necessary to increase the pressure resistance of the separation apparatus used, and separation can be performed efficiently.
Further, before separating the oil phase and the glycerin phase, it is preferable to add water for washing the alkali catalyst.

In the second stage, depending on the transesterification rate in the first stage, the conditions such as the amount of lower alkyl alcohol added, the processing temperature and processing time, and the amount of catalyst added in the second stage should be set more gently than in the first stage. Preferably, the amount of the lower alkyl alcohol added is preferably 1 to 20 parts by mass, more preferably 5 to 10 parts by mass with respect to 100 parts by mass of the oil phase supplied in the second stage. Within such a range, the lower alkyl alcohol can be recovered and purified at low cost, and a sufficient transesterification rate can be obtained. The amount of the alkali catalyst is preferably 0.01 to 0.2 parts by mass, more preferably 0.05 to 0.2 parts by mass, and still more preferably 0.05 to 0.00 parts by mass with respect to 100 parts by mass of the oil phase. If it is 1 mass part and it is such a range, transesterification can be performed efficiently, suppressing the byproduct of soap.
Moreover, the processing temperature of the 2nd stage becomes like this. Preferably it is 40-70 degreeC, More preferably, it is 50-60 degreeC. Within such a range, the speed of the transesterification reaction is sufficient, and it is not necessary to increase the pressure resistance of the apparatus to be used, which is efficient. The treatment time for the second stage is preferably 1 to 15 minutes, more preferably 3 to 10 minutes. Within such a range, it is possible to achieve a sufficient transesterification rate without requiring excessive time.

After completion of the second stage, the oil phase mainly composed of fatty acid lower alkyl ester and the glycerin phase are separated, and the oil phase is sent to the distillation step (C), and the glycerin phase is recycled (R) ).
The separation between the oil phase and the glycerin phase here can be performed by stationary separation, centrifugation, etc., as in the separation performed between the first stage and the second stage, and the separability is improved. The temperature is preferably 30 to 70 ° C., more preferably 40 to 70 ° C., and the standing time is preferably 30 to 90 minutes, more preferably 30 to 60 minutes, because it is not necessary to increase the pressure resistance of the separation device. do it. In addition, when separating the oil phase and the glycerin phase, it is preferable to add water for washing glycerin, lower alkyl alcohol and the like. In this case, the amount of water added is the transesterification step (B). 10-30 mass parts is preferable with respect to 100 mass parts of the mixture obtained by this, and 10-20 mass parts is more preferable. Within such a range, effective water washing can be performed without causing emulsification.

[Recycling process (R)]
The recycling step (R) is a step in which the soap in the glycerin phase by-produced in the transesterification reaction step (B) is decomposed with an acid into a fatty acid under the conditions of pH 2 to 5, and this fatty acid is returned. The fatty acid may be returned to the esterification step (A) or may be returned to the step on the preceding stage. Specifically, the case where it returns to a degumming process (P) and the case where it returns to a raw material storage tank can be illustrated.
The by-product soap is poor in quality, so it is difficult to use it as a soap as it is, but by using such a recycling step (R) as a fatty acid and reusing it as a raw material, the production yield can be increased. . In the glycerin phase, in addition to glycerin and soap, usually a lower alkyl alcohol (methanol in the illustrated example), an alkali catalyst, water and the like are present.

As a specific method of the recycling step (R), the following method is preferable.
First, without separating and removing the lower alkyl alcohol from the glycerin phase produced in the transesterification step (B), an acid is added to the glycerin phase as it is to adjust the pH to 2 to 5, preferably 3 to 4. And preferably, it is 10-70 degreeC, More preferably, it is 40-60 degreeC temperature conditions, Preferably it is 30-360 minutes, More preferably, it is 60-120 minutes, this is stirred and mixed and the mixture containing a fatty acid is produced | generated.
Here, if the pH is less than 2, the apparatus may corrode, and if it exceeds 5, the decomposition tends to be difficult. Further, when the temperature is 10 to 70 ° C., it is not necessary to increase the pressure resistance of the apparatus, and the decomposition proceeds at a sufficient rate. Further, when the stirring and mixing time is 30 to 360 minutes, a sufficient decomposition rate can be achieved without increasing the size of the apparatus. Moreover, according to the method of adding an acid without separating and removing the lower alkyl alcohol from the glycerin phase as described above, the acid decomposition can be performed at a low temperature and in a short time.

  Here, sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid and the like can be used as the acid, but sulfuric acid is preferred. When sulfuric acid is used as the acid and sodium hydroxide is used as the alkali catalyst in the transesterification step (B), sodium sulfate is by-produced along with the fatty acid. The sodium sulfate produced as a by-product in this manner is separated and removed from the fatty acid. However, sodium sulfate is preferable because it is excellent in separability and is not mixed into the fatty acid. Here, for example, when hydrochloric acid is used as the acid and sodium hydroxide is used as the alkali catalyst in the transesterification step (B), sodium chloride is produced as a by-product, but sodium chloride has separability. It is bad and easy to mix with fatty acids. Since fatty acids are reused, it is required to contain as little impurities as possible. Therefore, it is preferable to use sulfuric acid as the acid.

  First, sodium sulfate is removed by centrifugation or the like from the mixture containing fatty acid and by-product sodium sulfate, and then some lower alkyl alcohol, glycerin and water are removed. Then, water is added to the mixture from which these are removed, and the mixture is further separated into a phase containing fatty acid as a main component and a phase containing water, lower alkyl alcohol and glycerin. And the phase which has a fatty acid as a main component is returned.

On the other hand, about the phase containing water, lower alkyl alcohol, and glycerin, water and lower alkyl alcohol are normally distilled by flash distillation at 120-200 degreeC, and crude glycerin is obtained as a residue. The water and lower alkyl alcohol distilled by flash distillation are then introduced into a lower alkyl alcohol rectification column and operated at 60 to 120 ° C. to recover the lower alkyl alcohol as a distillate and to leave waste water. Remove as a thing.
In addition, when transesterification process (B) is performed in two or more stages, it is preferable to separate and recover the glycerin phase at the end of each stage and to use all of these for this recycling process (R).

[Distillation step (C)]
The distillation step (C) includes at least a vacuum distillation step for distilling the fatty acid lower alkyl ester from the oil phase obtained in the transesterification step (B), and thus at least the vacuum distillation step is performed. By including, the impurities contained in the oil phase can be left as a residue at the bottom of the tower, and the target fatty acid lower alkyl ester can be obtained in high purity as a distillate. The impurities contained in the residue vary depending on the type of animal and vegetable oils and fats used in the raw material. There are components derived from alkali metals, carotene degradation products, and the like.

  Since each component contained in the residue is thought to cause clogging of the fuel supply line and the fuel injection nozzle, after such a distillation step (C), the possibility of clogging is suppressed to a low level. A high-purity fatty acid lower alkyl ester that is suitable as an alternative fuel and that satisfies the EU standard for a light oil alternative fuel can be obtained. Further, according to such a distillation step (D), for example, when crude palm oil or the like is used as a raw material, a colored product such as carotene originally contained therein is decomposed and left as a decomposed product in a residue at the bottom of the tower. Therefore, it is possible to obtain a fatty acid lower alkyl ester having no brown color derived therefrom, without separately performing the step of removing the colored product.

Furthermore, the distillation step (C) is preferably provided with a vacuum distillation step of two or more stages in which the number of carbon atoms of the fatty acid lower alkyl ester to be distilled is different.
Specifically, first, a normal pressure flash distillation step (usually 120 to 170 ° C.) is performed to remove lower alkyl alcohol (methanol in the illustrated example) and water as a distillate. Next, a vacuum distillation step of two or more stages is performed on the residue.
For two or more vacuum distillation steps, it is preferable to set the distillation conditions for each vacuum distillation step so that the carbon number of the fatty acid alkyl ester to be distilled is different for each vacuum distillation step. Then, the conditions are set so that the fatty acid lower alkyl ester having a larger carbon number is distilled out. In each vacuum distillation step, a plurality of fatty acid lower alkyl esters having different carbon numbers may be mixed and distilled, but in that case, the average value of the carbon number is changed from the front side to the rear side. It only needs to be larger.

  Thus, the fatty acid lower alkyl ester of higher purity can be obtained by performing the vacuum distillation process in two or more stages. That is, there are a plurality of fatty acid lower alkyl esters having different carbon numbers in the oil phase, and these generally have different boiling points. Therefore, for example, if the distillation under reduced pressure is carried out in one stage, and the distillation conditions suitable for distillation of the fatty acid lower alkyl ester on the high carbon number side which is the main component of the oil phase are set, during the distillation, The fatty acid lower alkyl ester on the low carbon number side, which is a minor component, suddenly boils, and as a result, the monoglyceride remaining at the bottom of the distillation column is easily entrained in the distillate, and the resulting fatty acid lower alkyl ester on the high carbon number side is obtained. The purity and properties of the will decrease. In that regard, when the vacuum distillation step is performed in two or more stages, the optimum distillation conditions according to the number of carbon atoms can be set in each step, and thus the fatty acid lower alkyl ester obtained is highly pure. The fatty acid lower alkyl ester obtained in each vacuum distillation step is finally mixed and used as a light oil alternative fuel.

For example, when the raw material mainly contains palm oil mainly composed of oils and fats derived from fatty acids having 16 and 18 carbon atoms, first, in the first vacuum distillation step, as shown in FIG. A distillate containing a fatty acid lower alkyl ester having a lower carbon number than the main component (fatty acid lower alkyl ester derived from a fatty acid having 12 or 14 carbon atoms) is obtained, and then the carbon number is reduced in the second vacuum distillation step. A method (method (1)) for obtaining a distillate containing a fatty acid lower alkyl ester derived from 16, 18 fatty acids is preferred.
Alternatively, in the first vacuum distillation step, together with a fatty acid lower alkyl ester derived from a fatty acid having 12 or 14 carbon atoms, a distillate containing a part of the fatty acid lower alkyl ester derived from a fatty acid having 16 carbon atoms is obtained, Subsequently, in the second vacuum distillation step, a distillate containing a fatty acid lower alkyl ester fatty acid derived from the remaining fatty acid having 16 carbon atoms and a fatty acid lower alkyl ester derived from a fatty acid having 18 carbon atoms (method (2 )) Or a distillate containing a fatty acid lower alkyl ester derived from a fatty acid having 12, 14 or 16 carbon atoms in the first vacuum distillation step, and then in the second vacuum distillation step, A method (method (3)) for obtaining a distillate containing a fatty acid lower alkyl ester derived from a fatty acid is preferred.

  In this case, in the case of the above-mentioned method (1), the first vacuum distillation step may be such that the top pressure of the distillation column is 1 to 3 kPa, the top temperature is 178 to 190 ° C., and the reflux ratio is 10 to 15. Preferably, in the case of the above method (2) or (3), it is preferable that the top pressure of the distillation column is 0.6 to 2.5 kPa, the top temperature is 183 to 206 ° C., and the reflux ratio is 0 to 2. .

The conditions of the second vacuum distillation step, which is the final vacuum distillation step, can be set as appropriate in any of the above methods (1) to (3), but (i) the top pressure of the distillation column is set to 0. 0. 1-1 kPa, preferably 0.2-0.5 kPa, bottom pressure is 2-5 kPa, preferably 3-4 kPa, and (ii) the top temperature of the distillation column is 150-200 ° C., preferably 160-180 ° C., The bottom temperature is 190 to 220 ° C, preferably 200 to 210 ° C, (iii) the reflux ratio is 0 to 1, preferably 0 to 0.5, and the evaporation rate is 95 to 99%, preferably 95 to 98%. By doing so, it becomes possible to control the content of glyceride in the distillate to 0.1% by mass or less, and a higher-purity fatty acid lower alkyl ester can be obtained.
In addition, such conditions are suitable when the main components of the animal and vegetable oils and fats that are raw materials are derived from fatty acids having 16 and / or 18 carbon atoms such as palm oil and rapeseed oil.

Here, the reflux ratio is the ratio of the reflux amount to the distillate amount, and the evaporation rate is the ratio (%) of the distillate amount to the charged (feed) liquid amount.
The top temperature and top pressure, the bottom temperature and the bottom pressure are the temperature and pressure measured at the top and bottom of the distillation column, respectively. The top is the top of the column where the distillate comes out, and the bottom is the residue. Is the bottom of the tower where

  In the above methods (2) and (3), at least a part of the fatty acid lower alkyl ester derived from the fatty acid having 16 carbon atoms is distilled in the first vacuum distillation step. This is because a fatty acid lower alkyl ester derived from a fatty acid having 16 carbon atoms has a high melting point and is likely to be crystallized at a low temperature, so that a liquid containing a large amount of this tends to decrease its fluidity. By previously distilling at least a part thereof in the first vacuum distillation step in advance, the fluidity of the liquid in the second vacuum distillation step is improved, and the distillation can be performed smoothly, The handleability of the distillate obtained in the vacuum distillation step 2 is also excellent. In the first vacuum distillation step, it is preferable to distill 50 to 100% by mass of a fatty acid lower alkyl ester derived from a fatty acid having 16 carbon atoms.

  In addition, in the case of oils and fats having a main component of carbon number 12 such as coconut oil, first, the number of carbon atoms on the lower carbon number side than the main component in the first vacuum distillation step. A distillate containing a fatty acid lower alkyl ester derived from fatty acids of 6, 8, 10 is obtained, and then a distillate containing a fatty acid lower alkyl ester derived from a fatty acid having 12 carbons is obtained in the second vacuum distillation step. It is preferable to obtain. In this case, in the first vacuum distillation step, it is preferable that the top pressure of the distillation column is 8 to 11 kPa, the top temperature is 135 to 175 ° C., and the reflux ratio is 1 to 2. In the second vacuum distillation step, it is preferable that the top pressure of the distillation column is 1 to 3 kPa, the top temperature is 178 to 190 ° C., and the reflux ratio is 10 to 15.

According to the production method as described above, an ester mixed oil having an acid value of 2 or less is obtained in the esterification step (A), and an alkali catalyst according to the acid value of the ester mixed oil in the transesterification step (B). Since the transesterification and the distillation step (C) are carried out while appropriately controlling the amount of water in a specific range, clogging is unlikely to occur when used as a light oil alternative fuel, and it is high enough to satisfy EU standards. Purity fatty acid lower alkyl ester can be stably produced in high yield. In the recycling step (R), the soap produced as a by-product in the transesterification reaction step (B) is acid-decomposed into fatty acid under the conditions of pH 2 to 5, and this is converted into the esterification step (A) or the preceding step. Since the process is returned to the process on the side, the fatty acid is effectively reused as a raw material, and a particularly high production yield can be achieved.
Specifically, a fatty acid lower alkyl ester having a purity of 99% by mass or more and a total glyceride content of 0.1% by mass or less is obtained in a yield of 90% or more.
Here, when at least one of these steps is not performed, the purity of the fatty acid lower alkyl ester is lowered, and the EU standard cannot be cleared, or the purity of the obtained fatty acid lower alkyl ester becomes unstable. Furthermore, industrially stable operations cannot be performed, for example, the production yield is reduced and the yield of the fatty acid lower alkyl ester is lowered.

  The fatty acid lower alkyl ester thus obtained can be suitably used as a light oil substitute fuel for all uses such as automobiles, ships, agricultural machinery, construction machinery, power generation, and heating. Moreover, you may mix and use with another fatty-acid alkylester, light oil, etc. as needed.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to the following Example at all.
In the following examples, “part” means “part by mass” and “%” means “% by mass” unless otherwise specified.
In each example, the moisture content was measured according to the Karl Fischer method.

[Example 1]
According to the following process, alkali deoxidized palm oil (NPO) produced in Malaysia was used as a raw material, and fatty acid methyl ester was produced therefrom. This alkaline deacidified palm oil contains 0.4% of carbon 12 component, 1.0% of carbon 14 component, 44.1% of carbon 16 component, and 18 of carbon component as fat. It contained 53.6% by mass and 1.0% by mass of a component having 20 carbon atoms, and further contained 1.6% of free fatty acid and 0.1% of gum. The acid value was 3.2 and the water content was 1000 ppm. Hereinafter, the number of carbon atoms refers to an ester that does not contain alcohol-derived carbon.

(1) Esterification step (A)
Methanol was passed through a column packed with Diaion SK104 (trade name, degree of crosslinking: 4%) manufactured by Mitsubishi Chemical Corporation, which is an acidic gel cation exchange resin, and washed. Next, a mixture in which 20 parts by mass of methanol was added to 100 parts by mass of the raw material (NPO) was supplied to the column and passed therethrough to obtain a reaction mixture. The acid value of the ester mixed oil in the reaction mixture was 0.14. The water content in the reaction mixture was 1800 ppm. The column temperature was 65 ° C., the column residence time was 120 minutes, and methanol having a water content of 600 ppm was used.

(2) Transesterification step (B)
The transesterification step (B) (first stage) was performed on the ester mixed oil obtained in (1) as follows.
First, methanol and sodium hydroxide as an alkali catalyst were added to a reaction mixture containing 84% of ester mixed oil. Here, the addition amount of methanol was 15 parts with respect to 120 parts of the reaction mixture, and the addition amount of sodium hydroxide was 0.2 parts with respect to 100 parts of the ester mixed oil.
And the oil phase which has fatty acid methyl ester as a main component, and the glycerin phase were produced | generated by making this react for 60 minutes with the processing temperature of 70 degreeC with an autoclave with a paddle stirrer.
Subsequently, this was allowed to stand at 40 ° C. for 60 minutes, then separated into an oil phase and a glycerin phase, and 14 parts of water for washing were added to 100 parts of the oil phase, and after stirring, this was carried out at 40 ° C. for 60 minutes. Left to stand. Then, this was separated into an oil phase and an aqueous phase (also referred to as a phase in which water-soluble substances such as soap, methanol, glycerin, sodium hydroxide are dissolved, also referred to as glycerin phase). The fatty acid methyl ester concentration (transesterification reaction rate) in the oil phase was 95.0%.

(3) Recycling process (R)
The glycerin phase obtained in the above (2) and the aqueous phase were mixed, 90% sulfuric acid was added to the mixture to adjust the pH to 3.0, and the mixture was stirred and mixed at 60 ° C. for 60 minutes. Subsequently, sodium sulfate produced from this mixture was removed by centrifugation, and then separated into a phase containing fatty acid as a main component (hereinafter referred to as fatty acid phase) and an aqueous phase containing water, methanol and glycerin.
About the aqueous phase containing water, methanol, and glycerin, water and methanol were removed by flash distillation at 150 ° C. to obtain crude glycerin. The water and methanol mixture distilled by flash distillation was then introduced into a methanol rectification column, distilled at 70 ° C. to recover methanol as a distillate, and waste water was removed as a residue.
On the other hand, 3 parts of the fatty acid phase was returned to and mixed with 100 parts of NPO as a raw material. The acid value of the obtained mixture was 6.2 and the water content was 1000 ppm.

(4) Esterification step (A) and transesterification step (B)
The reaction including the ester mixed oil having an acid value of 0.24 is performed on the mixture having the acid value of 6.2 obtained in the above (3) under the same conditions as in the above (1). A mixture was obtained. The water content in the reaction mixture was 3400 ppm.
Then, the transesterification step (B) is performed on this ester mixed oil under the same conditions as in the above (2) except that the amount of the alkali catalyst is 0.25 parts instead of 0.2 parts, and the oil phase and the glycerin phase Got. The fatty acid methyl ester concentration in the oil phase after washing with water was 95.5%.

(5) Distillation step (C)
The oil phase obtained in the above (4) was first flash distilled at a normal pressure of 150 ° C. to remove methanol and water as a distillate.
Next, a first vacuum distillation step (top temperature 190 ° C., top pressure 2.0 kPa) is performed on the residue of flash distillation, and fatty acid methyl ester derived from a fatty acid having 12 or 14 carbon atoms is used as a main component. A distillate was obtained.
Next, the second vacuum distillation step (top pressure 0.5 kPa, bottom pressure 3 kPa, top temperature 170 ° C., bottom temperature 210 ° C., reflux ratio 0.5, evaporation rate is applied to the residue of the first vacuum distillation step. 99%) to obtain a distillate containing fatty acid methyl esters derived from fatty acids having 16 and 18 carbon atoms as the main component.
Table 1 summarizes the properties, yields, etc. of the mixture of the distillate obtained in the first vacuum distillation step and the distillate obtained in the second vacuum distillation step.

[Example 2]
According to the following process, crude palm oil (CPO) produced in Malaysia was used as a raw material, and fatty acid methyl ester was produced therefrom.
This crude palm oil is a fat and oil of 0.3% carbon number component, 1.0% carbon number component 1.0%, carbon number 16 component 44.0%, carbon number 18 component 53. It contained 8% by mass and 0.9% by mass of a component having 20 carbon atoms, and further contained 3.74% free fatty acid and 0.5% gum. The acid value was 8.2.

(1) Degumming process (P)
1 part of warm water and 1 part of pearlite as an adsorbent were added to 100 parts by mass of crude palm oil heated to 65 ° C., and mixed and stirred for 20 minutes. Next, this was filtered under pressure using a jacket additional pressure filter (KST-142-JA-S) with NO-5C filter paper (filtration area: 113 cm ² ) manufactured by Advantec under a pressure of 1 kg / cm ² and a temperature of 45 ° C. Then, the insoluble matter containing gum was removed, and a degummed product (gum content 0.2%) was obtained as a filtrate. The moisture content of the degummed product was 600 ppm.

(2) Esterification step (A)
The esterification step (A) is carried out in the same manner as (1) of Example 1 except that 20 parts of methanol is used for 100 parts of the degummed product obtained in (1) above to obtain a reaction mixture. It was. The acid value of the ester mixed oil in the reaction mixture was 0.33. The water content in the reaction mixture was 2700 ppm.

(3) Transesterification step (B)
The transesterification step (B) (first stage) was carried out in the same manner as in (2) of Example 1 except that the addition amount of sodium hydroxide as an alkali catalyst was changed to 0.25 part. An oil phase as a component and a glycerin phase were produced.
Next, this was allowed to stand at 40 ° C. for 30 minutes, then separated into an oil phase and a glycerin phase, and 14 parts of water for washing were added to 100 parts of the oil phase, and after stirring, this was carried out at 40 ° C. for 60 minutes. Left to stand. Then, this was separated into an oil phase and an aqueous phase (a phase in which water-soluble substances such as soap, methanol, glycerin and sodium hydroxide are dissolved). The fatty acid methyl ester concentration in the oil phase was 95.3%.

(4) Recycling process (R)
The glycerin phase obtained in (3) above and the aqueous phase are mixed, and the mixture is subjected to the same treatment as in (1) of Example 1 to obtain the fatty acid phase, water, methanol, and glycerin. Separated into an aqueous phase containing.
About the water phase containing water, methanol, and glycerol, the process similar to Example 1 was implemented, while obtaining crude glycerol, the collection | recovery of methanol and the removal of waste water were performed.
On the other hand, the fatty acid phase was returned to the esterification step (A) and mixed so as to be 3 parts per 100 parts of the degummed product. The acid value of the obtained mixture was 10.6, and the water content was 600 ppm.

(5) Esterification step (A) and transesterification step (B)
The esterification step (A) is carried out on the mixture obtained in (4) with an acid value of 10.6 under the same conditions as in (2) above, and a reaction comprising an ester mixed oil with an acid value of 0.64 A mixture was obtained. The water content in the reaction mixture was 3500 ppm.
Then, the transesterification step (B) is performed on this ester mixed oil under the same conditions as in the above (3) except that the amount of the alkali catalyst is 0.3 parts instead of 0.25 parts, and the oil phase and the glycerin phase Got. The fatty acid methyl ester concentration in the oil phase after washing with water was 96.5%.

(6) Distillation step (C)
The oil phase obtained in (5) above is subjected to a flash distillation step, a first vacuum distillation step, and a second vacuum distillation step in the same manner as in (5) of Example 1 to obtain a first vacuum Table 1 summarizes the properties, yields, etc. of the mixture of the distillate obtained in the distillation step and the distillate obtained in the second vacuum distillation step.

[Example 3]
The fatty acid methyl ester was produced from the same Malaysian crude palm oil (CPO) used in Example 2 by the following steps.
(1) Degumming process (P)
In the same manner as in Example 2 (1), a degummed product was obtained from crude palm oil.
(2) Esterification step (A)
In the same manner as in (2) of Example 2, a reaction mixture containing an ester mixed oil (acid value 0.33) was obtained.

(3) Transesterification step (B)
The transesterification step (B) (two stages) was performed as follows on the ester mixed oil obtained in (2) above.
(I) First stage First, methanol and sodium hydroxide as an alkali catalyst were added to a reaction mixture containing 84% of an ester mixed oil. Here, the addition amount of methanol is 20 parts with respect to 120 parts of the reaction mixture, and the addition amount of sodium hydroxide is determined from the formula (1), and is 0.22 parts with respect to 100 parts of the ester mixed oil. .
And like this (2) of Example 1, this produces | generates the oil phase which has fatty acid methyl ester as a main component, and a glycerol phase, and after leaving still at 40 degreeC for 60 minutes, an oil phase and a glycerol phase Separated. The fatty acid methyl ester concentration in the oil phase was 96.2%.
(Ii) Second stage Next, 5 parts of methanol and 0.1 part of sodium hydroxide as an alkali catalyst are added to 100 parts of the obtained oil phase, and a transesterification reaction is carried out at a treatment temperature of 60 ° C. for 5 minutes. did.
To 100 parts by mass of the obtained mixture, 14 parts of water for washing was added, and after stirring, this was allowed to stand at 40 ° C. for 60 minutes. Then, this was separated into an oil phase and an aqueous phase (a phase in which water-soluble substances such as soap, methanol, glycerin and sodium hydroxide are dissolved). The fatty acid methyl ester concentration in the oil phase was 99.1%.

(4) Recycling process (R)
In the transesterification reaction of (3) above, the glycerin phase obtained in the first stage and the aqueous phase obtained in the second stage are mixed, and 90% sulfuric acid is added to the mixed solution to adjust the pH to 3. The mixture was stirred at 60 ° C. for 60 minutes. Next, sodium sulfate produced from this mixture was removed by centrifugation, and then separated into a fatty acid phase and an aqueous phase containing water, methanol, and glycerin.
About the water phase containing water, methanol, and glycerol, the process similar to Example 1 was implemented, while obtaining crude glycerol, the collection | recovery of methanol and the removal of waste water were performed.
On the other hand, 3 parts of the fatty acid phase was returned to and mixed with 100 parts of the degummed product. The acid value of the obtained mixture was 10.6, and the water content was 800 ppm.

(5) Esterification step (A) and transesterification step (B)
The esterification step (A) is carried out on the mixture obtained in (4) having an acid value of 10.6 under the same conditions as in Example 1 (1), and an ester mixture oil having an acid value of 0.64. A reaction mixture containing was obtained. The water content in the reaction mixture was 3700 ppm.
Then, a transesterification reaction step (B) consisting of two stages is performed on this ester mixed oil under the same conditions as in the above (3) except that the amount of catalyst in the first stage is 0.24 parts from the formula (1). An oil phase and a glycerin phase were obtained. The fatty acid methyl ester concentration in the oil phase after washing with water was 99.2%. At the end of the first stage, the fatty acid methyl ester concentration in the oil phase was 95.3%.

(6) Distillation step (C)
The oil phase obtained in (5) above is subjected to a flash distillation step, a first vacuum distillation step, and a second vacuum distillation step in the same manner as in (5) of Example 1 to obtain a first vacuum Table 1 summarizes the properties, yields, etc. of the mixture of the distillate obtained in the distillation step and the distillate obtained in the second vacuum distillation step.

[Example 4]
A fatty acid methyl ester was produced from the mixture of the degummed product obtained in (1) of Example 2 and domestic refined rapeseed oil (canola) as a raw material by the following steps. Refined rapeseed oil contains 5% of carbon 16 components, 94% of carbon 18 components, 1% of carbon 22 components, 0.1% free fatty acid, 0% gum Contained 1%.
(1) Esterification step (A)
60 parts of the degummed product obtained in (2) of Example 2 mixed with 40 parts of domestic refined rapeseed oil (canola) (acid number 4.9, free fatty acid content 2.28%, water content) A reaction mixture containing an ester mixed oil (acid value 0.20) was obtained in the same manner as in Example 1 except that the amount was 900 ppm). The water content in the reaction mixture was 2100 ppm.

(2) Transesterification step (B)
The transesterification step (B) (two stages) was performed on the ester mixed oil obtained in (1) in the same manner as in (3) of Example 3.
However, in the first-stage transesterification reaction, the amount of methanol added is 15 parts with respect to 120 parts of the reaction mixture, the amount of sodium hydroxide is determined from the formula (1), and the amount of ester mixed oil is 100 parts. 0.21 part.
The fatty acid methyl ester concentration in the oil phase obtained in the first stage was 95.3%.
Further, when the second-stage transesterification reaction was carried out in the same manner as in (3) of Example 3, the fatty acid methyl ester concentration in the oil phase obtained in the second-stage was 99.1%.

(3) Recycling process (R)
In the transesterification reaction of (2) above, 70% sulfuric acid was added to the glycerin phase obtained in the first stage to adjust the pH to 3.0, and the mixture was stirred and mixed at 60 ° C. for 60 minutes. Subsequently, the sodium sulfate produced was removed by centrifugation, and then the aqueous phase obtained in the second stage was mixed therewith. Then, 70% sulfuric acid was again added to the mixed solution to adjust the pH to 3.0, and the mixture was allowed to stand at 60 ° C. for 60 minutes to separate into a fatty acid phase and an aqueous phase mainly composed of methanol, glycerin and the like.
About the water phase which has methanol, glycerol, etc. as a main component, the process similar to Example 1 was implemented, while obtaining crude glycerol, the collection | recovery of methanol and the removal of waste water were performed.
On the other hand, 3 parts of the fatty acid phase were returned and mixed with respect to 100 parts of a mixture of 60 parts of degummed product and 40 parts of domestic refined rapeseed oil (canola). The acid value of the obtained mixture was 7.7, and the water content was 800 ppm.

(5) Esterification step (A) and transesterification step (B)
The esterification step (A) is carried out on the mixture obtained in the above (4) having an acid value of 7.7 under the same conditions as in Example 1 (1), and an ester mixed oil having an acid value of 0.31. A reaction mixture containing was obtained. A reaction mixture containing an ester mixed oil having an acid value of 0.24 was obtained. The water content in the reaction mixture was 2900 ppm.
Then, a two-stage transesterification step (B) is performed on this ester mixed oil under the same conditions as in (2) except that the amount of catalyst in the first stage is 0.22 parts, and the oil phase and the glycerin phase And got. The fatty acid methyl ester concentration in the oil phase after washing with water was 99.0%. Note that at the end of the first stage, the fatty acid methyl ester concentration in the oil phase was 95.1%.

(6) Distillation step (C)
The oil phase obtained in (5) above is subjected to a flash distillation step, a first vacuum distillation step, and a second vacuum distillation step in the same manner as in (5) of Example 1 to obtain a first vacuum Table 1 summarizes the properties, yields, etc. of the mixture of the distillate obtained in the distillation step and the distillate obtained in the second vacuum distillation step.

[Example 5]
As a raw material, a mixture obtained by adding 3 parts of the fatty acid phase obtained in (4) of Example 3 to 100 parts of the same crude palm oil used in Example 2 is used to produce a fatty acid methyl ester from the following steps. did.
(1) Degumming process (P)
To 103 parts of the mixture heated to 65 ° C., 0.05 part of an 80% aqueous phosphoric acid solution and 0.04 part of pearlite as an adsorbent were added and mixed and stirred for 10 minutes. Subsequently, this was pressure filtered in the same manner as in (2) of Example 2 to remove insoluble matter containing gum, and a degummed product (gum content 0.1%) was obtained as a filtrate. . The mixture used as a raw material had an acid value of 10.6, 3.74% free fatty acid, and 0.5% gum. The moisture content of the degummed product was 700 ppm.

(2) Esterification step (A)
Then, the esterification step (A) was performed in the same manner as in Example 1 except that 20 parts of methanol was used for 100 parts of the degummed product obtained in the above (1) to obtain a reaction mixture. The ester mixed oil in the reaction mixture had an acid value of 0.33 and the water content of the reaction mixture was 2800 ppm.

(3) Transesterification step (B)
The transesterification step (B) was performed in two stages in the same manner as in Example 3 on the ester mixed oil obtained in (2) above.
However, in the first-stage transesterification reaction, the amount of methanol added is 15 parts with respect to 120 parts of the reaction mixture, and the amount of sodium hydroxide added is determined from the formula (1). In contrast, it was 0.23 parts.
The fatty acid methyl ester concentration in the oil phase obtained in the first stage was 95.5%.
Further, when the second stage transesterification reaction was carried out in the same manner as in Example 3, the fatty acid methyl ester concentration in the oil phase obtained in the second stage was 99.4%.

(4) Recycling process (R)
The recycling step (R) was performed in the same manner as in Example 3. However, 3 parts of the fatty acid phase were returned and mixed with respect to 103 parts of the mixture of 100 parts of the degummed product and 3 parts of the fatty acid phase. The acid value of the obtained mixture was 10.6, and the water content was 500 ppm.

(5) Esterification step (A) and transesterification step (B)
The esterification step (A) is performed on the mixture obtained in (4) having an acid value of 10.6 under the same conditions as in Example 1 (1), and an ester mixed oil having an acid value of 0.42 is obtained. A reaction mixture containing was obtained. The water content in the reaction mixture was 3500 ppm.
Then, a two-stage transesterification step (B) is performed on this ester mixed oil under the same conditions as in the above (2) except that the amount of the first stage catalyst is 0.23 parts from the formula (1). An oil phase and a glycerin phase were obtained. The concentration of fatty acid methyl ester in the oil phase after washing with water was 99.3%. At the end of the first stage, the fatty acid methyl ester concentration in the oil phase was 95.3%.

(6) Distillation step (C)
The oil phase obtained in (5) above is subjected to a flash distillation step, a first vacuum distillation step, and a second vacuum distillation step in the same manner as in (5) of Example 1 to obtain a first vacuum Table 1 summarizes the properties, yields, etc. of the mixture of the distillate obtained in the distillation step and the distillate obtained in the second vacuum distillation step (pour point 14 ° C.).

[Example 6]
A fatty acid methyl ester was produced in the same manner as in Example 5 except that only the distillation step (C) was performed as described below.
That is, after the flash distillation process was performed on the oil phase in the same manner as in (5) of Example 1, the first vacuum distillation process and the second vacuum distillation process were performed. However, the first vacuum distillation step was performed under the conditions of a top pressure of 0.8 kPa, a bottom pressure of 2.5 kPa, a top temperature of 187 ° C., a bottom temperature of 210 ° C., and a reflux ratio of 0.5. In the second vacuum distillation step, the top pressure was 0.5 kPa, the bottom pressure was 2 kPa, the top temperature was 185, the bottom temperature was 215 ° C., the reflux ratio was 0.5, and the evaporation rate was 98%.
Thus, when the 1st vacuum distillation process and the 2nd vacuum distillation process were performed, in the 1st vacuum distillation process, the fatty acid methyl ester derived from the fatty acid of 12 or 14 carbon atoms and the fatty acid of 16 carbon atoms 50% of the fatty acid methyl esters derived from Moreover, in the 2nd vacuum distillation process, the distillate which has as a main component the fatty acid methyl ester derived from the remaining C16 fatty acid and the fatty acid methyl ester derived from a C18 fatty acid was obtained. Further, this distillate had a pour point (JIS K 2269) of 5 ° C., which was 9 ° C. lower than that of Example 5, and was excellent in fluidity.
Table 1 summarizes the properties, yields, etc. of the mixture of the distillate obtained in the first vacuum distillation step and the distillate obtained in the second vacuum distillation step.

[Comparative Example 1]
Except for not performing the degumming step (P) and the esterification step (A), the same procedure as in Example 2 (the amount of the alkali catalyst (sodium hydroxide) is 0.25 part), the transesterification step (B) is performed. went. However, the transesterification reaction hardly proceeded, and the resulting mixture was allowed to stand at 40 ° C. for 30 minutes, but was not separated into an oil phase and a glycerin phase.

[Comparative Example 2]
A transesterification step (B) was carried out in the same manner as in Comparative Example 1 except that the amount of sodium hydroxide was changed to 0.8 part. The obtained mixture was allowed to stand at 40 ° C. for 30 minutes, separated into an oil phase and a glycerin phase, 10 parts of water was added to 100 parts of the oil phase, and after stirring, this was allowed to stand at 40 ° C. for 60 minutes. It separated into an oil phase and an aqueous phase. The fatty acid methyl ester concentration in the oil phase was 94.0%.
Next, the distillation step (C) was performed on the oil phase under the same conditions as in Example 1.
About what mixed the distillate obtained by the 1st vacuum distillation process, the 2nd vacuum distillation process, the distillate obtained by the 1st vacuum distillation process, and the 2nd vacuum distillation process, The properties and yields are summarized in Table 1.

[Comparative Example 3]
In the same manner as in Example 3, the process from the degumming process to the distillation process was performed.
However, the conditions of the esterification step were changed so that the acid value of the resulting ester mixture was 4. The results are summarized in Table 1.

[Comparative Example 4]
In the same manner as in Example 3, the process from the degumming process to the distillation process was performed.
However, the catalyst amount in the first stage of the transesterification step of (3) and (5) was 1.5 parts. The results are summarized in Table 1.

[Comparative Example 5]
In the same manner as in Example 3, the process from the degumming process to the distillation process was performed.
However, the recycling process (R) was not performed. The results are summarized in Table 1.

The concentration of the fatty acid methyl ester was determined by gas chromatography (GC) using a calibration curve prepared in advance. That is, about 0.2 g of the sample after pretreatment was taken into a blood collection bottle, dissolved by adding about 1 g of n-hexane, and operated under the following GC measurement conditions, and the concentration of each fraction was calculated from the calibration curve.
The calibration curve was prepared by dissolving each fatty acid methyl ester standard product (6 to 22 carbon atoms, manufactured by Wako Pure Chemical Industries, Ltd.) in n-hexane and preparing a standard solution so as to have a predetermined concentration. Was prepared by GC analysis under the following conditions.
<GC measurement conditions>
・ GC: Shimadzu Corporation, product name GC6A
Column: DEGS (diethylene glycol succinate 20%) Column temperature: 180 ° C., inlet temperature: 250 ° C.
Detector temperature: 250 ° C., RANGE (10 ⁿ ): n = 3
Carrier gas: N _2, 50 mL / min, detector: FID, injector: 1 μL

The content of glyceride is about 20 mg of sample collected in a vial, 100 μL of pyridine and 200 μL of BSTFA (bistrimethylsilyltrifluoroacetamide) are added and stirred well, heated at 80 ° C. for 30 minutes, and then cooled to room temperature Was determined by GC measurement.
<GC measurement conditions>
Column: DB-HT (capillary column, J & W), column temperature: initial 50 ° C. to 400 ° C. at 10 ° C./min. Inlet temperature: 380 ° C., detector temperature: 400 ° C., detector: FID , Carrier gas: helium, split ratio: about 50: 1, sample injection amount: 1 μL

  As described above, in each Example, a high-purity fatty acid methyl ester that can clear the EU standard was stably obtained in a high yield.

It is a schematic process drawing which shows an example of the manufacturing method of this invention. It is a schematic process drawing which shows an example about a recycle process (R) among the manufacturing methods of this invention.

Claims (7)

A method for producing fatty acid lower alkyl esters for light oil alternative fuels from raw materials containing animal and vegetable fats and oils,
An esterification step (A) in which a fatty acid in the raw material is esterified with a lower alkyl alcohol using a cation exchange resin to obtain a reaction mixture containing an ester mixed oil having an acid value of 2 or less;
While adjusting the amount of the alkali catalyst within the range of 0.1 to 1 part by mass with respect to 100 parts by mass of the ester mixed oil according to the acid value, the fats and oils in the ester mixed oil are esterified with a lower alkyl alcohol. A transesterification step (B) comprising at least a first step for exchange;
The soap produced as a by-product in the transesterification reaction step (B) is decomposed with an acid under the conditions of pH 2 to 5 to give a fatty acid, and the fatty acid is converted into the fatty acid before the esterification step (A) or the esterification step (A). Recycling process (R) to return to the process on the side,
And a distillation step (C) having at least a vacuum distillation step for distilling the fatty acid lower alkyl ester from the oil phase obtained in the transesterification step (B). Method.   When the said animal and vegetable fats and oils are unrefined fats and oils, it has the degumming process (P) which removes a gum from this unrefined fats and oils in the front | former stage side of the said esterification process (A), It is characterized by the above-mentioned. A method for producing a lower alkyl ester of fatty acid.   The degumming step (P) is a step of mixing the unmodified oil and fat with a modifier made of phosphoric acid and an adsorbent made of pearlite, and filtering the resulting mixture. The manufacturing method of fatty-acid lower alkyl ester of description.   The method for producing a fatty acid lower alkyl ester according to any one of claims 1 to 3, wherein the transesterification step (B) comprises two steps.   5. The method according to claim 1, wherein sodium hydroxide is used as the alkali catalyst and sulfuric acid is used as the acid, and sodium sulfate is by-produced in the recycling step (R). A method for producing a fatty acid lower alkyl ester.   The fatty acid lower alkyl ester according to any one of claims 1 to 5, wherein the distillation step (C) includes a vacuum distillation step of two or more stages in which the number of carbon atoms of the fatty acid lower alkyl ester to be distilled is different. Manufacturing method. When the main component of the animal and vegetable oils and fats is oils and fats derived from fatty acids having 16 and / or 18 carbon atoms, the glyceride content in the distillate distilled in the last step of the vacuum distillation step is 0. The fatty acid lower alkyl ester production according to claim 6, wherein the distillation conditions of the last step are set so as to satisfy the following (i) to (iii) so as to be 1% by mass or less. Method.
(I) The top pressure of the distillation column is 0.1 to 1 kPa, and the bottom pressure is 2 to 5 kPa. (Ii) The top temperature of the distillation column is 150 to 200 ° C, and the bottom temperature is 190 to 220 ° C.
(Iii) The reflux ratio is 0 to 1, and the evaporation rate is 95 to 99%.

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