Cleaning and liquid contact with solids – Processes – Using sequentially applied treating agents
Reexamination Certificate
2000-03-01
2004-02-24
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
Using sequentially applied treating agents
C134S002000, C134S022100, C134S022120, C134S022170, C134S029000, C134S035000, C134S036000, C134S040000, C134S042000, C203S008000, C203S037000, C203SDIG002
Reexamination Certificate
active
06695928
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for the production of (meth)acrylic acid and/or (meth)acrylic esters. More specifically, it relates to a method for the production of (meth)acrylic acid and/or (meth)acrylic esters, characterized by removing solid substances such as polymer and precipitate which adhere to devices and pipes to be used for the production of (meth)acrylic acid and/or (meth)acrylic esters.
2. Description of the Related Art
It is well known that (meth)acrylic acid and/or (meth)acrylic esters are susceptible to polymerization and, during the process of production thereof, often generate polymers and oblige relevant devices to stop. It has been universally known to cope with this trouble by adding a polymerization inhibitor such as hydroquinone and phenothiazine to the relevant raw material prior to the production of (meth)acrylic acid and the like or performing a surface treatment on the relevant devices for the purpose of preventing solid substances such as polymer and precipitate from adhering to the devices. None of these measures, however, has attained perfect prevention of occurrence and adhesion of solid substances such as polymer and precipitate.
U.S. Pat. No. 5,728,272 discloses a method which, with a view to facilitating the removal of generated polymer, comprises stopping and washing the relevant devices while the cumulative amount of a generated polymer is small. The effect of this method in preventing the occurrence of solid substances such as polymer and precipitate, however, does not deserve to be rated fully satisfactory.
SUMMARY OF THE INVENTION
The object of the present invention is the provision of a method for inhibiting the occurrence of solid substances such as polymer and precipitate during the process for production of (meth)acrylic acid and/or (meth)acrylic esters, particularly for inhibiting the occurrence and adhesion of solid substances such as polymer or polymerized material and precipitate on the heated surfaces of a boiler and a jacket.
Further by this invention, the formation of (meth)acrylic acid due to the decomposition of an ester during the process for purification of (meth)acrylic ester can be effectively prevented.
The present inventors have found by their study that the occurrence and adhesion of such solid substances as polymer and precipitate which are formed during the process for production of (meth)acrylic acid and/or (meth)acrylic esters and the formation of (meth)acrylic acid due to the decomposition of an ester during the process of purification of (meth)acrylic esters are caused by the basic substance which emanates in a small amount from a basic solution used in washing devices and reaches the respective sites of production and purification. This invention has been perfected as a result.
Specifically, according to the invention it can provide a method for the production of (meth)acrylic acid and/or (meth)acrylic esters characterized by, when the production thereof is stopped, washing the device constructed for producing (meth)acrylic acid and/or (meth)acrylic esters with a basic solution for the purpose of removing solid substances such as polymer and precipitate formed on the surfaces of a flow way of(meth)acrylic acid and/or (meth)acrylic esters in the device during the course of the production and subsequently rinsing the device with a solvent.
According to the method of this invention, namely by washing devices, pipes, and the like with a basic solution during the process of production of (meth)acrylic acid and/or (meth)acrylic esters and thereafter rinsing them with a solvent, it is made possible to remove such solid substances as polymer and precipitate which adhere to the parts of devices and pipes in a short time and realize protracted operation of the process for the production of (meth)acrylic acid and/or (meth)acrylic esters.
Particularly in the case of the process for the production of (meth)acrylic esters, the formation of (meth)acrylic acid due to the decomposition of such esters can be effectively prevented.
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 EMBODIMENTS
The expression “process for the production of (meth)acrylic acid and/or (meth)acrylic esters” as used herein refers to a step of cooling a (meth)acrylic acid-containing gas obtained by the catalytic vapor phase oxidation of a propylene and/or acrolein containing gas with a solvent and collecting (absorbing) the cooled gas by counter flow washing, a step of recovering (meth)acrylic acid from the collected (absorbed) mixture of the solvent and the (meth)acrylic acid (JP-B-06-15,496), and a step of esterifying the (meth)acrylic acid and recovering the resultant (meth)acrylic ester (JP-A-10-231,275). Examples of the (meth)acrylic ester may include alkyl acrylates such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, butyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.
The process which continues till recovery of the formed (meth)acrylic acid comprises devices such as an absorption column for absorbing (meth)acrylic acid from the reaction gas of (meth)acrylic acid, a stripping column, an extraction column, a solvent separation column, an azeotropic separation column in which dehydration is performed with an azeotropic solvent, an acetic acid separation column, a high boiling component separation column for removing high boiling substances such as a stabilizer, a rectification column, and a storage tank, a condenser, a re-boiler, a strainer, and a pump which are accessories of the devices annexed to the upper, middle or lower part thereof, and pipes for example between the columns, and between any of the columns and any of the accessories thereof mentioned above.
Then, the process which continues till recovery of a (meth)acrylic ester comprises devices such as a reaction column or tower for the esterification of (meth)acrylic acid with an alcohol, an ester extraction column, a more volatile component separation column, a rectification column, and a storage tank, a condenser, a re-boiler, a strainer, and a pump which are accessories of the devices annexed to the upper, middle or lower part thereof, and pipes for example between the columns, and between any of the columns and any of the accessories thereof mentioned above.
The distillation column to be used in this invention is not particularly discriminated but has only to be capable of effecting distillation. Examples of the distillation column may include a packed column, a tray column, a wetted-wall column, and a spray column. The term “distillation column” as used herein means to include accessories for a distillation column such as a heat exchanger, a condenser, a re-boiler, and a jacket. Among other items mentioned above, the device is preferred to include a distillation column and accessories of a distillation column such as a heat exchanger, a re-boiler, and a jacket.
In general, polymer and precipitate adhere to the surface of a flow way of (meth)acrylic acid and/or an (meth)acrylic ester in the state of liquid and/or vapor in the devices, accessories, and pipes between them. In the present invention, the adhered polymer and precipitate can be removed by means of a special washing in particular without overhauling the system of devices, accessories, and pipes between them constructed for the production of (meth)acrylic acid and/or an (meth)acrylic ester.
The basic solution to be used in this invention is not particularly discriminated but is only required to be a solution of a basic substance. It is preferred to be an aqueous solution of at least one member selected from the group consisting of an oxide, hydroxide, carbonate, and hydrogen carbonate of an alkali metal such as lithium, sodium, potassium, and rubidium, an oxide and hydroxide of an alkaline earth metal such as magnesium, calcium, strontium, and barium,
Nakahara Sei
Nishimura Takeshi
Ueoka Masatoshi
Gulakowski Randy
Kornakov M.
Mathews, Collins Shepherd & McKay, P.A.
Nippon Shokubai Co. , Ltd.
LandOfFree
Method for production of (meth) acrylic acid and/or... 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 and/or..., 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 and/or... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3287142