Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2000-06-28
2003-12-23
Rotman, Alan L. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S485000, C562S532000, C562S538000, C562S545000
Reexamination Certificate
active
06667419
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for absorbing (meth)acrylic acid and/or (meth)acrolein and an apparatus therefor More specifically, it relates to a method for absorbing (meth)acrylic acid and/or (meth)acrolein in the operation of an absorption column so adapted as to collect a (meth)acrylic acid and/or (meth)acrolein -containing gas, for example, arising from catalytic gas phase oxidation by causing the gas to contact a solvent for the purpose of effecting efficient absorption of the gas while preventing the (meth)acrylic acid or the like from polymerization and an apparatus therefor.
2. Description of the Related Art
From the gas containing (meth)acrylic acid which is obtained by subjecting propylene, for example, to catalytic gas phase oxidation with a molecular oxygen-containing gas in the presence of an oxidizing catalyst, the solution of (meth)acrylic acid, for example, is obtained by leading the gas to an absorption column for (meth)acrylic acid and allowing the gas to cool therein by contact with a solvent.
Generally by technological reasons, the absorption column is of the packing type. U.S. Pat. No. 5,785,821 proposes use of a random packing (cascade mini rings) and U.S. Pat. No. 5,780,679 proposes use of a sheet structured packing (MELLAPAK) in the absorption column of this type. The column, however, requires an unduly large height for the purpose of effecting the absorption of (meth)acrylic acid, for example, with as high efficiency as expected. Since the absorption column entails gradual adhesion of a polymer to the interior thereof and encounters gradual decline of the efficiency of absorption with the elapse of the time spent for its operation, it rather frequently calls for a work of interrupting the operation of the column and removing the adhering polymer.
SUMMARY OF THE INVENTION
It is an object of this invention, therefore, to solve such problems of the prior art as mentioned above and provide a method for absorbing (meth)acrylic acid and/or (meth)acrolein in the absorption column for (meth)acrylic acid and/or (meth)acrolein for the purpose of effecting the required absorption of the compound with high efficiency while preventing the compound from succumbing to polymerization and an apparatus therefor.
The object of this invention is accomplished by providing, in an absorption column adapted to establish countercurrent contact between the gas containing (meth)acrylic acid and/or (meth)acrolein arising from catalytic gas phase oxidation and a solvent, a method for absorbing (meth)acrylic acid and/or (meth)acrolein, which is characterized by having a packing of relatively high efficiency of absorption installed on the upstream side of the flow of a liquid containing the solvent and a packing and/or a plate tower of relatively low performance of polymerization installed on the downstream side thereof, inside the column.
The object of this invention is further accomplished by providing, in an absorption column adapted to establish countercurrent contact between the gas containing (meth)acrylic acid and/or (meth)acrolein arising from catalytic gas phase oxidation and a solvent, an apparatus for the absorption of (meth)acrylic acid and/or (meth) acrolein, which is characterized by having a packing of relatively high efficiency of absorption installed on the upstream side of the flow of a liquid containing the solvent and a packing and/or a plate tower of relatively low performance of polymerization installed on the downstream side thereof, inside the column.
The method of this invention is capable of absorbing (meth)acrylic acid and/or (meth)acrolein with high efficiency and satisfactorily preventing (meth)acrylic acid and/or (meth)acrolein from polymerization as well owing to the use of a packing and/or tray of different kinds.
The apparatus of this invention is enabled by a simple configuration to effect absorption of (meth)acrylic acid and/or (meth)acrolein with high efficiency and, at the same time, preclude (meth)acrylic acid and/or (meth)acrolein from polymerization.
REFERENCES:
patent: 3868417 (1975-02-01), Duembgen et al.
patent: 3957880 (1976-05-01), Sate et al.
patent: 4092132 (1978-05-01), Leacock
patent: 4333894 (1982-06-01), Hoppe et al.
patent: 4543219 (1985-09-01), Yamato et al.
patent: 5426221 (1995-06-01), Willersinn
patent: 5780679 (1998-07-01), Egly et al.
patent: 5785821 (1998-07-01), Sakamoto et al.
patent: 0856343 (1998-08-01), None
Inada Misao
Matsumoto Yukihiro
Nishimura Takeshi
Sakamoto Kazuhiko
Mathews, Collins Shepherd & McKay, P.A.
Nippon Shokubai Co. , Ltd.
Oh Taylor V.
Rotman Alan L.
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