JPH0138439B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for transesterification of oils and fats using a catalyst solution containing alkali hydroxide as a main component.

[Conventional technology]

In general, the main component of fats and oils is triesters of fatty acids and glycerin (so-called triglycerides), and the properties of each fat and oil differ depending on the bond position between the fatty acids and glycerin that make up the triglyceride. By changing the state, the unique properties of oils and fats can be changed. A reaction that changes the bonding state between fats and oils and glycerin in a certain direction is usually called a direct transesterification reaction, whereas a reaction that randomly arranges all the fatty acids is a random transesterification reaction. Although these exchange reactions are called reactions, these exchange reactions are possible for a single type of oil and fat, as well as for a complex type of mixed fat and oil. is well known to be used as a catalyst.
Here, reactions using alkali metals (e.g., sodium, potassium, etc.) and alkali metal alcoholates (e.g., sodium methylate, etc.) have the advantage of being carried out at relatively low temperatures; There are considerable problems in terms of yield, coloring of the product, and the degree of influence caused by the water content of the raw material fats and oils, and the use of alkali metal hydroxides (e.g., caustic soda, caustic potash, etc.) The reaction has the advantage that the catalyst is relatively easy to handle, and the product is less colored and post-processing is easy, but since water is used to dissolve the catalyst, it can cause saponification of oils and fats. In order to avoid this, the water removal process is carried out as quickly as possible (usually around 60°C is said to be appropriate) and the transesterification process (usually around 140°C is said to be appropriate).
It has been considered that two steps are essential:

In order for the transesterification reaction to proceed smoothly, it is natural that the catalyst, which is insoluble in fats and oils, needs to be dispersed in the fats and oils in the form of particles as fine as possible. A method in which the catalyst is mixed and dispersed in oils and fats using a dynamic mixer, dehydrated in a vacuum reaction vessel, and then heated to proceed with the reaction (for example,
(JAOCS Vol. 55, p. 803), or a method in which oils and fats are mixed with a catalyst solution, sprayed and dehydrated under vacuum, and then heated to proceed with the reaction; alternatively, a method in which the mixture is homogenized and then dehydrated ( For example, JP-A-58-
Publication No. 79098) etc. have been disclosed.

However, methods using various dynamic mixers
It takes a considerable amount of time to remove water from the added catalyst, during which time some of the oils and fats are saponified, and spray dehydration not only requires quite large equipment to remove water from the catalyst. It is also necessary to heat the liquid temperature, which drops due to spraying, to raise it again, and the other method of dehydrating after homogenization is simply the opposite of the previous method, and the equipment is still Neither method is preferable since it requires a large amount of effort.

[Problems to be Solved by the Invention] This invention solves the most important problem, particularly in the transesterification reaction of fats and oils using an alkali hydroxide catalyst, which is the addition of a catalyst to fats and oils and the removal of water from a mixture of fats and oils and a catalyst. The technical challenge is to develop methods and equipment to carry out these processes extremely effectively.

[Means to solve the problem]

In order to solve the above problems, this invention mixes and homogenizes and disperses a catalyst solution containing alkali hydroxide as a main component and oils and fats in a thin film state under reduced pressure.
Transesterification of oils and fats, which is characterized by efficiently removing moisture in the system and at the same time heating to start the transesterification reaction, and further maintaining the temperature required for the reaction for a certain period of time to complete the reaction. A reaction method (first invention), and efficiently mixing, homogenizing, and dispersing a catalyst solution containing an alkali hydroxide as a main component and oils and fats, removing water and heating to start a transesterification reaction, Furthermore, an apparatus for transesterification of oils and fats (second invention) is provided, which is characterized by a vacuum centrifugal thin film heat exchange apparatus for completing the reaction.The details of these inventions will be described below.

First, the alkali hydroxide of the present invention is, for example, a hydroxide of sodium or potassium, and a catalyst solution is prepared by adding water alone or water and glycerin to the alkali hydroxide. The mixing ratio of alkali hydroxide, glycerin and water in this catalyst solution is usually 1:(2-3):(3-10) by weight, and 0.1-1.0% (by weight) based on the fats and oils. ) is preferable because it allows the transesterification reaction to proceed smoothly.

Here, the fats and oils of this invention include animal fats and oils such as lard, beef tallow, fish oil, and hydrogenated oils thereof;
Soybean oil, rapeseed oil, corn oil, palm oil, safflower oil, cottonseed oil, rice oil, coconut oil, olive oil,
It may be vegetable oils such as sunflower oil or these hydrogenated oils, or fractionated oils or mixtures of two or more of these animal and vegetable oils, and the acid value is conveniently 2 or less, preferably 0.5 or less. . In order to completely dissolve such fats and oils, it is desirable to heat them in advance to about 60°C and transfer them to a vacuum centrifugal thin film heat exchanger using a pump or the like.

A catalyst solution is also fed into the same device for mixing, homogenization, and dispersion.

The mixture of mixed, homogenized and dispersed oils and fats and catalyst solution may cause a saponification reaction of the oils and fats due to the alkali and water inside, so remove the moisture immediately, for example within 30 seconds. , must initiate the required transesterification reaction. For this purpose, if a vacuum centrifugal thin film heat exchanger is used under a reduced pressure of 10 mm-Hg or less, preferably 4 mm-Hg or less, the oils and fats will be uniformly dispersed in fine particles and difficult to remove. Water particles that are present are also easily removed.

The mixture, which has been dehydrated in this way and the transesterification reaction has started, is maintained at a reaction temperature of 130 to 170° C. for a certain period of time (for example, 1 to 45 minutes) in order to complete the transesterification reaction.

Since the catalyst and other impurities remain in the mixture that has completed the transesterification reaction in this way, the mixture is transferred to the normal oil refining process either at the reaction temperature or after being cooled, and after removing the catalyst and impurities, it is deodorized. The treatment yields deodorized refined fats and oils.

〔Example〕

Example: First, an apparatus as shown in FIG. 1 was installed. That is, the catalyst solution in tank 1 and the raw material oil and fat in tank 2 are transferred by pumps, and are mixed, homogenized, and dispersed in a vacuum centrifugal thin film heat exchanger 3 to perform a transesterification reaction, and then transferred to a cooling device. This is a device designed to be sent out from the system from 6. Further, the vacuum centrifugal thin film heat exchanger 3 has a second
As shown in the figure and Fig. 3, a mixture of oils and fats and a catalyst solution enters from the inlet 5, and the mixture is moved to the side wall by the centrifugal force caused by the rotation of the blade 6, and is formed into a thin film by the action of the centrifugal force and the blade. It has a structure in which it gradually moves upwards due to hydraulic pressure, and a jacket is provided around the outer periphery to increase the dehydration efficiency, allowing the mixture inside to be heated to a higher temperature. In addition, after the dehydration is finished and the transesterification reaction starts, the finished mixture is sent from the liquid outlet 7 to the cooling device 4.
The generated gas, which is mainly composed of water vapor, is sucked through the gas outlet 8 and discharged to the outside of the system.

Using the apparatus described above, refined palm oil (acid value 0.05) heated to 60°C in advance is used as a raw material fat, and a catalyst solution with a weight ratio of caustic soda, glycerin, and water of 10:20:70 is vacuum centrifuged. The mixture is fed into the thin film heat exchanger 3 for mixing, homogenization, and dispersion, and the pressure is reduced to 4 mm ^- Hg.
Further dehydration treatment was completed using a vacuum centrifugal thin film heat exchanger 3 adjusted to 150°C, and at the same time, transesterification was started, allowed to proceed, and completed. In this example, the minimum amount of catalyst required to carry out 90% or more of the transesterification reaction was 0.12% based on the fat and oil. Here, the degree of progress of the reaction was determined by comparing the fatty acid composition of 2-monoglyceride using hydrolysis of fats and oils by lipase with the fatty acid composition before the reaction.

Comparative example: The same raw material oil and catalyst solution used in the example were premixed, moisture was immediately removed under reduced pressure to 4 mm-Hg, and the mixture was placed in a normal vacuum reaction vessel (150°C).
The transesterification reaction was completed by In this case, the minimum amount of catalyst required to carry out the transesterification reaction by 90% or more was 0.5% based on the fat and oil.

〔effect〕

Taking all the above into account, it is clear that by using the method and apparatus of the present invention, transesterification of oils and fats using an alkali hydroxide catalyst can be carried out very efficiently. Therefore, it can be said that the significance of this invention is extremely large.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an apparatus to show an example of the method and apparatus for transesterification of oils and fats of the present invention, Fig. 2 is an enlarged longitudinal section of a vacuum centrifugal thin film heat exchange apparatus, and Fig. 3 is a FIG. 1, 2...Tank, 3...Vacuum centrifugal thin film heat exchange device, 4...Cooling device, 5...Inlet, 6...Blade, 7...Liquid outlet, 8...Gas outlet.

Claims (1)

[Claims] 1. A catalyst solution containing an alkali hydroxide as a main component and oils and fats are mixed, homogenized, and dispersed in a thin film state under reduced pressure, and the water in the system is quickly removed, and at the same time heated to form an ester. A method for transesterification of oils and fats, which comprises starting the exchange reaction and then maintaining the temperature necessary for the reaction for a certain period of time to complete the reaction. 2. The method for transesterification of oils and fats according to claim 1, wherein the catalyst solution is an aqueous solution containing water or water and glycerin in addition to the alkali hydroxide. 3. The method for transesterification of fats and oils according to claim 1, wherein the catalyst solution is 0.1 to 1.0% (by weight) based on the fats and oils. 4 Reduced pressure is 10mm-Hg or less, preferably 4mm
-Hg or less, the method for transesterification of oils and fats according to claim 1. 5. A patent claim in which a mixture of oils and fats and a catalyst is mixed, homogenized, and dispersed in a thin film state under reduced pressure, and the water in the system is quickly removed, and at the same time, the temperature at which the transesterification reaction is initiated by heating is 130 to 170°C. A method for transesterification of oils and fats according to item 1. 6. The method for transesterification of oils and fats according to claim 1, wherein the time required from the start to completion of the transesterification is 1 to 45 minutes. 7 Fats and oils include animal fats and oils such as lard, beef tallow, fish oil, or these hydrogenated oils, soybean oil, rapeseed oil, corn oil, palm oil, safflower oil, cottonseed oil, rice oil, coconut oil, olive oil, sunflower oil, or any of these. The method of transesterification of oils and fats according to claim 1, which is vegetable oils and fats such as hydrogenated oils, as well as fractionated oils or mixed oils of two or more of these animal and vegetable oils. 8. The method for transesterification of fats and oils according to claim 1, wherein the fats and oils have an acid value of 2 or less, preferably 0.5 or less. 9 A system for supplying a catalyst solution containing alkali hydroxide as a main component, a system for supplying oils and fats, and a mixture system of the catalyst solution and raw material oils supplied from these systems are removed under reduced pressure. 1. An apparatus for transesterification of oils and fats, comprising a vacuum centrifugal thin film type heat exchange reactor for heating to initiate transesterification and further to complete the reaction. 10. The apparatus for transesterification of oils and fats according to claim 9, wherein the catalyst solution is an aqueous solution containing water or water and glycerin in addition to the alkali hydroxide. 11. The apparatus for transesterification of fats and oils according to claim 9, wherein the catalyst solution is 0.1 to 1.0% (by weight) based on the fats and oils. 12 Reduced pressure is 10 mm-Hg or less, preferably 4
The apparatus for transesterification of oils and fats according to claim 9, which is in a state of not more than mm-Hg. 13 Claim 9: A mixture of oils and fats and a catalyst is mixed and dispersed in a thin film state under reduced pressure to quickly remove water in the system, and at the same time heated to start the transesterification reaction at a temperature of 130 to 170°C. Apparatus for the transesterification reaction of oils and fats as described in 2. 14. The apparatus for transesterification of oils and fats according to claim 9, wherein the time required from the start to completion of the transesterification is 1 to 45 minutes. 15 Fats and oils include animal fats and oils such as lard, beef tallow, fish oil, or these hydrogenated oils, soybean oil, rapeseed oil, corn oil, palm oil, safflower oil, cottonseed oil, rice oil, coconut oil, olive oil, sunflower oil, or any of these. 10. The apparatus for transesterification of oils and fats according to claim 9, which is vegetable oils and fats such as hydrogenated oils, as well as fractionated oils or mixed oils of two or more of these animal and vegetable oils. 16. The apparatus for transesterification of fats and oils according to claim 9, wherein the fats and oils have an acid value of 2 or less, preferably 0.5 or less.