Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
2001-06-22
2002-06-18
Carr, Deborah (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
C554S163000, C554S169000
Reexamination Certificate
active
06407269
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a catalyst for transesterification.
PRIOR ART
As a catalyst for transesterification, heterogeneous catalysts have been examined from the viewpoint of separating a catalyst-component after reaction. For example, there are known a method for utilizing an inorganic solid acid such as silica-alumina and zeolite (JP-A 61-200943), a catalyst containing aluminum oxide and/or iron oxide (JP-A 61-236749), a method for using a silicate or the like of the group IV elements (EP0623581A2), a method for utilizing an organic solid acid such as an ion-exchange resin (WO98/25876) and a method for using hydrous zirconium oxide (JP-B 4-28250).
However, the heterogeneous catalysts described above could not satisfy all of activity, selectivity and durability in transesterification. Specifically, the inorganic solid acid has strong acid-strength, and for example, a zeolite such as mordenite gives rise to significant formation of an undesirable by-product such as an ether upon transesterification. The activity of the silicates of the group IV elements is relatively low, and thus there is a restriction that high temperature conditions must be adopted. Further, elution of silicon occurs during the reaction to permit a reduction in the activity during a long operation. The ion-exchange resin as an organic solid acid is low not only in activity but also in thermostability, and thus there is a limit upon its usable temperature range. Nevertheless, the patent using the ion-exchange resin describes the condition that the reaction is conducted in a gaseous phase, adjusting temperature and pressure. Accordingly, a catalyst using the ion-exchange resin is applicable to only low-boiling and low-molecular reactants and cannot be applied to high-boiling reactants. On one hand, the catalyst using the ion-exchange resin has the problem of swelling upon contact with lower alcohol. The utilization of the hydrous zirconium oxide is disclosed as a means of improving selectivity, but its industrial application is not achieved due to low activity thereof.
DISCLOSURE OF INVENTION
Accordingly, the object of the present invention is to provide a heterogeneous catalyst which is highly active, excellent in selectivity and free from elution of its catalytically active components and which has long lifetime.
The present invention relates to a catalyst for transesterification comprising a phosphate of at least one metal selected from the group consisting of aluminum, gallium and iron. Aluminum is particularly preferable.
Preferably, the molar ratio of the metal:phosphoric acid is from 1:3 to 1:0.01.
The catalyst may comprise a boric acid-group or an alkaline earth metal.
Also, the present invention relates to a method for producing a catalyst for transesterification, which comprises bringing a solution containing a phosphate ion into contact with at least one of an oxide, a hydroxide and a nitrate of at least one metal selected from the group consisting of aluminum, gallium and iron.
The above-mentioned method comprises preferably calcining, further.
In the above-mentioned method, the molar ratio of the metal ion to phosphate ion is preferably from 1:2 to 1:0.01.
The present invention relates to a method for producing an ester compound, which comprises transesterifying an alcohol, a carboxylic acid or an ester compound with a starting ester in the presence of a catalyst comprising a phosphate of at least one metal selected from the group consisting of aluminum, gallium and iron.
The present invention preferably provides a method for producing an ester compound, which comprises transesterifying an alcohol, a carboxylic acid or an ester compound with a starting ester in the presence of the catalyst as defined above.
In the above-mentioned method for producing an ester compound, the catalyst preferably comprises a boric acid-group or an alkaline earth metal.
In the above-mentioned method for producing an ester compound, the catalyst is preferably that obtained by the process as defined above.
The said catalyst can also be prepared from a metal phosphate and an alkaline earth metal, boric acid or a borate.
Further, the present invention relates to use of a phosphate of at least one metal selected from the group consisting of aluminum, gallium and iron as catalyst for transesterification.
MODES FOR CARRYING OUT INVENTION
In general, a phosphate may be in many forms such as orthophosphate, polyphosphate, metaphosphate and pyrophosphate. Then, as the catalyst of the present invention, orthophosphate is preferably used. However, a phosphate in other form may also be included without hindrance. The metal forming the phosphate of the present invention is one or more members selected from the group consisting of aluminum, gallium and iron. Among them, aluminum is particularly preferable. Further, two or more metal phosphates may be used as complex, and such metals are not limited the metals mentioned above.
As to the composition of the catalyst, the molar ratio of the metal ion to the phosphate ion is preferably 1:3 to 1:0.01, more preferably 1:3 to 1:0.1 and especially preferably 1:1.2 to 1:0.2, from the viewpoint of catalytic activity.
The phosphates used in the present invention may be commercially available or may be obtained by preparation. The form of the phosphate may be any of amorphous and crystalline one. For example, one of the amorphous phosphates can be obtained by allowing an alkaline substance to act on a mixture of a metal nitrate-solution and phosphoric acid, thereby obtaining a precipitate and following up with treatments such as filtration, washing with water, drying and calcination. The precipitate can be used as the catalyst in a dried form without subjection to calcination. In this case, formation of ethers is suppressed.
From the viewpoint of activity, it is preferable to calcine the catalyst for 0.1 hour or more at 150° C. or higher.
As to the composition of the catalyst obtained by precipitation, the molar ratio of the metal ion to the phosphate ion is preferably 1:3 to 1:0.1, more preferably 1:1.2 to 1:0.2, from the viewpoint of catalytic activity.
In preparing a metal phosphate or a complexed metal phosphate, a carrier (which may be a supporting member) having its large surface-area may be coexist to prepare an immobilized (or supported) metal phosphate or an immobilized (or supported) complexed metal phosphate on the carrier. The carrier may be used as one which is generally used for carrier such as silica, alumina, silica-alumina, titania, zirconia and an activated carbon. If the carrier is used in excess, the content of the phosphate as its active component is lowered to make the activity low. Accordingly, the ratio of the carrier to the catalyst is preferably not more than 90% by weight.
The method for making a phosphate ion adhere to a metal oxide etc. by bringing a solution of the phosphate ion into contact with the metal oxide etc. includes the method (a) in which the metal oxide etc. are dispersed in the solution of the phosphate ion and a solvent thereof is evaporated from the dispersion to allow the phosphate ion to adhere to the metal oxide etc. as they are (impregnation), the method (b) in which the solution of the phosphate ion is passed through metal oxide etc. followed by drying, and the method (c) in which metal oxide etc. are impregnated with the solution of the phosphate ion in an amount corresponding to the pore capacity of the metal oxide etc. followed by drying (Incipient Wetting Method). Among them, the method (a) is generally used.
The phosphate ion may be added in such an amount that a ratio of phosphorus atom to metal atom is 0.01 to 2.0, in the catalyst obtained by calcination. It is more preferable that the ratio is 0.05 to 1.0.
Calcination of the catalyst is preferably conducted at a temperature in the range of 150 to 1000° C. and it is more preferably done in the range of 200 to 800° C. The effect can be sufficiently obtained by means of calcination in a short time under this temperature condition, but the said temperature is preferab
Fukuoka Noriaki
Hattori Yasuyuki
Kaita Jun
Mimura Taku
Carr Deborah
Kao Corporation
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