Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2001-01-30
2003-11-04
Rotman, Alan L. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S598000
Reexamination Certificate
active
06642414
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for the production of (meth)acrylic acid.
2. Description of the Related Art
Heretofore, (meth)acrylic acid has been produced by subjecting propylene and/or acrolein or isobutylene and/or methacrolein to catalytic gas phase oxidation. Since the product of this reaction contains by-products such as (meth)acrolein, acetic acid, and formaldehyde besides the (meth)acrylic acid, it is necessary for the purpose of producing the (meth)acrylic acid in high purity to separate and remove such by-products by the use of distillation or the like.
JP-A-61-218,556, for example, discloses a method which, in a process of removing a light boiling substance by the operation of distillation or stripping from the aqueous acrylic acid solution resulting from the operation of cooling condensing an acrylic acid-containing gas and then separating and refining acrylic acid from the resultant aqueous acrylic acid solution by treating the aqueous acrylic acid solution sequentially through the step of extraction, the step of solvent separation, the step of light boiling substance separation, the step of heavy boiling substance separation, and the step of effecting refinement by repeated distillation, comprises subjecting the aqueous acrylic acid solution supplied to the step of extraction or the extractant derived in a form containing an extraction solvent and acrylic acid from this step to a treatment for the admixture of an aqueous solution of bisulfites and further admixing a hydrazine compound with the acrylic acid containing solution in at least one step selected from among the steps of solvent separation, of light boiling substance separation, of heavy boiling substance separation, and of effecting refinement by repeated distillation.
The method disclosed in this publication, however, necessitates separation into two layers the product of the admixture of the aqueous bisulfite solution with the acrylic acid containing solution, and consequently complicates the relevant operation.
It also entails the problem of readily generating a polymer at the step of heavy substance separation and the step of effecting refinement by repeated distillation.
It further entails the problem of inducing clogging of the pipe being used in transferring the bottoms as for the purpose of waste disposal at the step of effecting refinement by repeated distillation.
SUMMARY OF THE INVENTION
This invention has been produced in the light of the state of affairs mentioned above and has for an object thereof the provision of a method for repressing the generation of a polymer and permitting production of (meth)acrylic acid of high purity in a high yield.
The object of this invention is achieved by a method for the production of (meth)acrylic acid which comprising
(a) a step of obtaining a gaseous reaction product containing (meth)acrylic acid by subjecting at least one member selected from the group consisting of propylene, propane, acrolein, and mixtures thereof (for the case of producing acrylic acid) or at least one member selected from the group consisting of isobutylene, t-butyl alcohol, methyl-t-butyl ether, methacrolein, and mixtures thereof (for the case of producing methacrylic acid) to the reaction of catalytic gas phase oxidation,
(b) a step of absorbing the gaseous reaction product by the use of a solvent,
(c) a step of separating the solvent, a low boiling impurity, and a high boiling impurity from the (meth)acrylic acid solution absorbed with the solvent mentioned above by extraction and/or distillation and obtaining crude (meth)acrylic acid solution containing aldehydes and the like having boiling points approximating closely to the boiling point of (meth)acrylic acid as impurities,
(d) a step of adding an aldehyde treating agent to the crude (meth)acrylic acid mentioned above and subjecting the resultant mixture to vacuum distillation thereby obtaining (meth)acrylic acid of high purity, and
(e) a step of returning the waste liquid generated at the step (d) mentioned above to the step (b) and/or the step (c).
This invention is capable of repressing the generation of a polymer and, at the same time, increasing the yield of (meth)acrylic acid of high purity.
In accordance with this invention, the circulation of the waste liquid permits elimination of the otherwise necessary disposal of the waste liquid generated at the step (d) and represses the trouble of clogging of the pipe for discharging the bottoms.
The above and other objects, features and advantages of the present invention will become clear from the following description of the preferred embodiments.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
This invention will be specifically described below based on the respective steps (a)-(e) by citing a typical example of the method for the production of acrylic acid.
Step (a)
The step of obtaining a gaseous reaction product containing acrylic acid by subjecting at least one member selected from the group consisting of propylene, acrolein, and a mixture thereof to the reaction of catalytic gas phase oxidation
This step is not particularly restricted so long as it is capable of obtaining acrylic acid by the reaction of catalytic gas phase oxidation. For example, the following known method may be adopted.
Propylene and/or acrolein are oxidized by being allowed to contact oxygen or a molecular oxygen-containing gas such as air in the presence of a known catalyst. Generally, the reaction of oxidation is carried out in two stages. The catalyst to be effectively used in the first stage of the reaction is only required to be capable of causing gas phase oxidation of a raw material gas containing propylene and forming mainly acrolein, and the catalyst to be effectively used in the second stage of the reaction to be capable of causing gas phase oxidation of a raw material gas containing acrolein and forming mainly acrylic acid. For example, a complex oxide that contains iron, molybdenum, and bismuth can be cited as the catalyst for the first stage, and a catalyst having vanadium as an essential component as the catalyst for the second stage. The temperature of the oxidation is generally in the range of 250-380° C. (see JP-A-11-130,722).
The gaseous reaction product obtained by this reaction of catalytic gas phase oxidation contains acrylic acid, molecular oxygen-containing gas, and the unreacted raw materials and further contains by-produced water and such impurities as acetic acid, propionic acid, maleic acid, acetone, acrolein, furfural, and formaldehyde.
Step (b)
The step (b) of absorbing the gaseous reaction product mentioned above by the use of a solvent
For the purpose of recovering acrolein and/or acrylic acid from the gaseous reaction product obtained at the step (a), the gaseous reaction product is contacted with a solvent. The solvent is not particularly defined but only required to be capable of absorbing and dissolving acrolein and/or acrylic acid. As examples of the solvent usable herein, organic compounds such as diphenyl ether, diphenyl, and a mixture thereof, water and organic substances such as acrylic acid, and acetic acid may be cited. Further, the wastewater that is generated during the step of production of acrylic acid, the waste liquid occurring in a vacuum generating device, and occasionally the cleaning water may be mixed and used as the solvent. The resultant solution containing the produced acrylic acid will be referred to hereinafter as “acrylic acid solution”.
The contact of the acrylic acid-containing gaseous reaction product with the solvent may be effected by adopting any of the known methods which are available for establishing the contact of the sort in question. As examples of the method usable herein, crossflow contacts using a bubble-cap tray, a uniflux tray, a sieve tray, a jet tray, a valve tray, a ventury tray, and an arbitrary combination thereof; and counterflow contacts using a turbo grid tray, a dual flow tray, a ripple tray, a kittel tray, a random packing, a structure packing, and an arbitrary c
Matsumoto Yukihiro
Mitsumoto Tetsuji
Nakahara Sei
Yoshimura Tatsuaki
Mathews, Collins Shepherd & McKay, P.A.
Nippon Shokubai Co. , Ltd.
Oh Taylor V.
Rotman Alan L.
LandOfFree
Method for production of (meth) acrylic acid does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for production of (meth) acrylic acid, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for production of (meth) acrylic acid will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3171469