Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-12-15
2001-11-27
Aulakh, Charanjit S. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S266000, C549S263000, C549S328000, C502S104000, C502S106000
Reexamination Certificate
active
06323347
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a catalyst for preparing a lactone, which is prepared by supporting a cupric compound, a zinc compound and at least one alkaline earth metal compound on the supporter. The present invention also relates to a method for preparing a lactone, which comprises a dehydrocyclization reaction of a diol under a gas phase in the presence of the aforementioned catalyst after activating said catalyst.
BACKGROUND OF THE INVENTION
Lactone, such as &ggr;-butyrolactone, may be used as a herbicide, used in the pharmaceutical composition, or used for preparing an intermediate; this intermediate is used to prepare pyrrolidone (such as N-methylpyrrolidone, 2-pyrrolidone and N-vinylpyrrolidone), piperidine, phenylbutyric acid and thiobutyric acid. Thus, developing an economic method for preparing &ggr;-butyrolactone is a common industrial requirement.
Previously, &ggr;-butyrolactone was commonly produced by a hydrogenation reaction with maleic anhydride or maleic acid ester under liquid phase or gas phase. However, this is an undesirable industrial process because the process needs a lot of hydrogen gas and its catalyst has a short lifetime.
Recently, &ggr;-butyrolactone was produced by a dehydrocyclization reaction with 1,4-butanediol, where a hydrogen by-product was generated as a raw material and as fuel. This method for preparing &ggr;-butyrolactone through the dehydrocyclization reaction of 1,4-butanediol is disclosed in Japanese Patent Unexamined Publication No. Sho-58-13575, wherein the dehydrocyclization reaction is carried out under liquid phase using a platinum/lead catalyst; however, the activity of said catalyst is low and the selectivity of &ggr;-butyrolactone is also low. The method disclosed in Japanese Patent Unexamined Publication No. Sho-61-246173 describes that &ggr;-butyrolactone is obtained by passing 1,4-butanediol vapor through a copper/chromium/zinc catalyst; however, this method may generate many tetrahydrofuran and butanol by-products, and the selectivity and yield of &ggr;-butyrolactone is usually low. The method disclosed in Japanese Patent Unexamined Publication No. Hei-3-232874 describes that &ggr;-butyrolactone is produced by passing 1,4-butanediol vapor through a copper/chromium/manganese or barium catalyst; the method disclosed in U.S. Pat. No. 5,110,954 describes that &ggr;-butyrolactone is obtained by adding 1,4-butanediol into the solution of copper/chromium catalyst; and the method disclosed in Japanese Patent Unexamined Publication No. Hei-2-255668 describes that &ggr;-butyrolactone is produced by passing 1,4-butanediol vapor through a copper/zinc/alkali metal catalyst. However, the activity of these catalysts may decay quickly, and the conversion of 1,4-butylene glycol may become lower after reacting over a long period. Therefore, it is undesirable as an industrial process.
The present inventors have deeply studied the above defects of the traditional technique and found more effective catalyst for preparing a lactone in the catalyst supporting a cupric compound, a zinc compound and at least one alkaline earth metal compound. The process for preparing lactone through the dehydrocyclization reaction of diol using the above catalyst under gas phase may increase the activity and lifetime of catalyst, while the selectivity may be up to 99 mol % or more; therefore the beneficial economic effect of industrial processes may be substantially increased. We have hereby accomplished the present invention.
SUMMARY OF THE INVENTION
The present invention relates to a catalyst for preparing a lactone, which is prepared by supporting a cupric compound, a zinc compound and at least one alkaline earth metal compound on the supporter. The present invention also relates to a method for preparing a lactone, which comprises a dehydrocyclization reaction of a diol under a gas phase in the presence of the aforementioned catalyst after activating said catalyst. The catalyst for preparing lactone of the present invention is quite economic because of its high activity, long lifetime and high selectivity of products.
DETAILED DESCRIPTION OF THE INVENTION
The catalyst of the present invention used for preparing a lactone is prepared by supporting a cupric compound, a zinc compound and at least one alkaline earth metal compound on the supporter. The suitable materials for the supporter used in the catalyst of the present invention are silica, alumina, or their mixture, more preferably the mixture of silica and alumina.
In the catalyst of the present invention used for preparing lactone, the cupric compound may be various cupric salts, of which the examples are copper (II) nitrate (Cu(NO
3
)
2
.3H
2
O), copper (II) carbonate (Cu
2
(OH)
2
CO
3
), copper (II) acetate (Cu(CH
3
COO)
2
), copper (II) chloride (CuCl
2
.2H
2
O), copper (II) hydroxide (Cu(OH)
2
), copper (II) phosphate (Cu
3
(PO
4
)
2
.3H
2
O), copper (II) sulfate (CuSO
4
.5H
2
O), etc. The zinc compound used in the catalyst of the present invention may be various zinc salts, of which the example are zinc nitrate (Zn(NO
3
)
2
.6H
2
O), zinc carbonate (ZnCO
3
), zinc acetate (Zn(CH
3
COO)
2
.2H
2
O), zinc chloride (ZnCl
2
), zinc hydroxide (Zn(OH)
2
), zinc sulfate (ZnSO
4
.7H
2
O), etc. The alkaline earth metal compound used in the catalyst of the present invention is at least one selected from a metal compound consisting of beryllium, magnesium, calcium, strontium and barium, and more preferably at least one selected from a metal compound consisting of magnesium, calcium and barium, which comprises their carbonate, hydroxide, silicate, phosphate, etc.
The catalyst of the present invention used for preparing a lactone is prepared according to the following method. The supporter is immersed in the above aqueous cupric salt and zinc salt solutions, and the value of pH is adjusted between 8 and 11 using ammonia water, while the hydroxides of copper and zinc are precipitated on the supporter. The precipitate is washed with water and dried. The precipitate is immersed in the above aqueous salts solution selected from one or two alkaline earth metal compound(s) consisting of magnesium, calcium and barium, and then calcined for 3 to 5 hours at 400 to 500° C. If it is necessary, a mold-aid agent such as graphite may be added, and a predeterminate shape is molded by a molding machine. In such resultant catalyst, each metal component exists in the form of oxide. Therefore, before the dehydrogenation reaction of diol, the catalyst must be reduced and be activated at a temperature ranging from 180 to 250° C. for 6 to 20 hours with hydrogen gas wherein the ratio of hydrogen gas to nitrogen gas starts between 1:20 and 1:10 by volume, then gradually adjusts to all hydrogen gas.
In the catalyst of the present invention used for preparing lactone, the ratio of copper (II) oxide to zinc oxide is usually 6:1 to 1:2 by weight, preferably 5:1 to 1:1. When any one of the alkaline earth metal compounds selected from a group consisting of magnesium, calcium and barium is used, its amount is preferably 0.01 to 10 wt %, more preferably 0.05 to 5 wt %, based on the total weight of copper (II) oxide and zinc oxide in terms of oxides. When any two of the alkaline earth metal compounds selected from a group consisting of magnesium, calcium and barium is used, their amounts are preferably 0.5 to 20 wt %, more preferably 1 to 10 wt %, based on the total weight of copper (II) oxide and zinc oxide in terms of oxides. The amount of support is preferably 0.5 to 20 wt %, more preferably 1 to 10 wt %, based on the total weight of copper (II) oxide and zinc oxide in terms of silica.
The present invention also relates to a method for preparing a lactone, which comprises a dehydrocyclization reaction of a diol under a gas phase in the presence of the aforementioned catalyst after activating said catalyst.
The example of the lactone used in the method for preparing lactone of the present invention includes, for instance, &bgr;-propiolactone, &bgr;-butyrolactone, &ggr;-butyrolactone, &ggr;-valerolactone, &dgr;-butyro
Chen Shien-Chang
Hsu Liang-An
Lin Fu-Shen
Tsai Cheng-Lin
Aulakh Charanjit S.
Dairen Chemical Corporation
Michael & Best & Friedrich LLP
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