Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
2000-08-14
2001-09-11
Carr, Deborah D. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
active
06288251
ABSTRACT:
This application is a 371 of PCT/JP99/0543 filed Oct. 1, 1999.
TECHNICAL FIELD
The present invention relates to a process for preparing or producing a fatty acid alkylester which can be effectively used as a fuel oil for diesel engines, for instance, through a transesterification of triglyceride contained in a variety of fats and oils including plant oils such as rape oil, sesame oil, soybean oil, corn oil, sunflower oil, palm oil, palm kernel oil, coconut oil, corn oil and safflower oil, animal oils such as beef fat, lard and fish oil, and, in addition, waste edible oils, i.e., spent oils of these plant and animal oils, with an alcohol.
BACKGROUND ART
Currently, large quantities of edible fats and oils as mentioned above are used in our country. Although a certain part of spent oils (aforementioned waste edible oils) is recycled as a raw material for producing soap, for example, they are mostly conveyed to a refuse dump without being recovered to be burned together with other combustible wastes or disposed in landfills together with incombustible wastes in actuality.
It has been known that a fatty acid alkylester could be obtained by subjecting major ingredients of fats and oils such as monoglyceride, diglyceride and triglyceride, to a transesterification with an alkyl alcohol (Handbook of Organic Chemistry, published by Gihodo Shuppan, 1988, pp. 1407-1409). Various attempts using the transesterification have thus far been made to produce an alkylester usable as a diesel engine fuel oil from the aforementioned oils and fats, as disclosed in Japanese Unexamined Patent Publication Nos. 7-197047 and 7-310090, for example. It has not been possible, however, to obtain any alkylester complying with current requirements of the Japanese Industrial Standards (JIS) imposed on light oil products by such prior art technology.
In a typical industrial process for a production of a fatty acid ester from triglyceride, in particular triglyceride contained in natural fats and oils, a fatty acid glyceride is caused to react with a lower alcohol in the presence of a metal alkali catalyst at normal pressure and at a temperature near the boiling point of the lower alcohol. The reaction process, however, uses the metal alkali catalyst dissolved in the reaction solution. Therefore, the metal alkali catalyst remains dissolved in the liquid reaction product obtained by this reaction process, resulting in a problem that it is difficult to separate and recover the metal alkali catalyst from the liquid reaction product.
There are another problems as follows. Natural fats and oils generally contain a large amount of free, i.e., unesterified, fatty acids. The amount of free fatty acids depends on origins of the raw material fats and oils and processes of them. On the average, it is more than 3 weight % of the fats and oils. When a metal alkali catalyst is used in the reaction solution having a large amount of free fatty acids, a fatty acid soap may be generated as a by-product of the transesterification, resulting in the need of an excessively large amount of the metal alkali catalyst. Alternatively,the fatty acid soap makes it difficult to separate a fatty acid ester layer from a glycerin layer in the liquid reaction product. To solve these problems, a pre-treatment process for removing the free fatty acids from the reaction solution is necessary for a transesterification of a fatty acid glyceride with an alcohol in the presence of the metal alkali catalyst.
To solve the above-mentioned problems, Japanese Unexamined Patent Publication No. 61-14044 discloses a process of transforming the free fatty acids into a fatty acid ester in the presence of an acid catalyst as the pre-treatment process for removing the free fatty acids. That is, in this process, the free fatty acids are pre-treated to be transformed into an ester, followed by a transesterification of a fatty acid glyceride in the presence of a metal alkali catalyst. However, when the transesterification is performed with the acid catalyst, which has been used in the pre-treatment process, remaining in the reaction solution, a part of the metal alkali catalyst to be used for the transesterification is neutralized by such a remained acid catalyst. Thus, there exists a problem that such a transesterification requires an increased amount of the metal alkali catalyst to compensate for the neutralized part of the metal alkali catalyst.
In addition, Japanese Unexamined Patent Publication No. 6-313188, for example, suggests a process for producing a fatty acid ester in which a solid acid catalyst is used to eliminate the need of the above-mentioned pre-treatment process. However, acid catalysts including the solid acid catalyst have a serious drawback, that is, their catalytic activity is lower than that of metal alkali catalysts in the transesterification of fats and oils. Thus, there exists a problem that the transesterification using acid catalysts needs a larger catalyst amount.
The present invention is aimed at overcoming the aforementioned problems residing in the prior art technology. It is therefore an object of the invention to provide a process for preparing or producing a fatty acid alkylester from fats and oils, in which it is possible to eliminate the pre-treatment process for esterifying the free fatty acids contained in the fats and oils and, by suppressing the by-production of a fatty acid soap, to eliminate or simplify recovering and refining processes of the reaction product.
DISCLOSURE OF THE INVENTION
According to a main feature of the present invention, in a process for producing a fatty acid alkylester through a transesterification of triglyceride contained in a fat and oil by causing the fat and oil and an alcohol to react with each other, the reaction between the fat and oil and the alcohol is performed in an atmosphere in which the alcohol is in super-critical state in the absence of metal alkali and acid catalysts.
In a preferred form of the invention, the transesterification is performed in a tube reactor through which the fat and oil and the alcohol are passed continuously to react with each other. In such a case that the tube reactor is used, the liquid hourly space velocity of triglyceride in the tube reactor is preferably set to 2 to 240/hr. In addition, the preferable alcohol may be a lower alcohol having 1 to 5 carbon atoms per molecule, from the viewpoint that the process for the present invention is particularly useful for the production of high quality fatty acid lower alkylester to be used as a diesel engine fuel oil.
BEST MODE FOR CARRYING OUT THE INVENTION
The inventors have performed an intensive study from a various point of view to find out a solution of the foregoing problems of the prior art. As a result, it has been found that an alkylester can be effectively produced from triglyceride contained in a fat and oil in the absence of a metal alkali catalyst and an acid catalyst by reacting the fat and oil with an alcohol in an atmosphere in which the alcohol is in a super-critical state. According to the process for the present invention, since none of a metal alkali catalyst and an acid catalyst is used for the reaction, eliminated can be the need of a pre-treatment process for esterifying free fatty acids contained in the fat and oil. In addition, using no metal alkali catalyst can eliminate or simplify the recovering and refining processes of the reaction product by suppressing the by-production of a fatty acid soap.
According to the present invention, the fats and oils include natural plant oils and animal oils. As plant oils, coconut oil, palm oil, palm kernel oil, soybean oil, rape oil or the like can be used. As animal oils, beef fat, lard, fish oil or the like can be used. In addition, the fats and oils may include waste edible oils, i.e., spent oils of these natural oils for a particular purpose. Although these fats and oils can be used singly or in combination, it is desirable to use waste edible oils to promote the recycling of resources.
On the other hand, as the alcohol to react with the fats and oils, i
Liu Guo-Tang
Tsuto Keiichi
Carr Deborah D.
Lonford Development Limited
Rosenthal & Osha L.L.P.
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