Daicel Corporation

Daicel Chemical Industries, Ltd.

Toppan Printing Co., Ltd.

Fuji Jukogyo Kabushiki Kaisha

Adeka Corporation

Hiroyuki Miura

Masahiko Shimizu

Ryuji Saito

Yoshihisa Mizutani

Takashi Ueno

Hidehiko Nakajima

Tomohide Ina

Hitoshi Watanabe

Takashi Sato

Hidetaka Kojima

Naruhisa Hirai

Ikuo Takahashi

Noboru Kamei

Masahiro Kagotani

Akihiro Kuwana

Kiyokazu Murata

Yoshiaki Morimoto

Kazushige Kitazawa

Masahide Tsuzuki

Ryota Chiba

Jun Chida

Hideyuki Yamada

Rikiya Morita

Teruo Matsuzaki

Takashi Yano

Kenichiro Kawazumi

Kazuo Yamaguchi

Mami Shimamura

Susumu Goda

Kensuke Goto

Daisuke Koiso

Masanobu Kayajima

A process for producing acetic acid by: a reaction step for continuously allowing methanol to react with carbon monoxide in the presence of a catalyst system comprising a metal catalyst, an ionic iodide, and methyl iodide in a carbonylation reactor, a flash distillation step for continuously feeding a flasher with a reaction mixture from the reactor and evaporating a volatile component at least containing product acetic acid, methyl acetate, and methyl iodide by flash distillation to separate the volatile component and a liquid catalyst mixture at least containing the metal catalyst and the ionic iodide, and an acetic acid collection step for separating a stream containing acetic acid from the volatile component to collect acetic acid; wherein, in the flash distillation step, the flash distillation is conducted under the condition that the concentration of methyl acetate in the liquid catalyst mixture is not less than 0.6% by weight.

Process for producing acetic acid

A production process of acetic acid according to the present invention inhibits concentration of hydrogen iodide and improves a liquid-liquid separation of an overhead from a distillation column. Acetic acid is produced by distilling a mixture containing hydrogen iodide, water, acetic acid and methyl acetate in a first distillation column () to form an overhead and a side cut stream or bottom stream containing acetic acid, cooling and condensing the overhead in a condenser (C) to form separated upper and lower phases in a decanter (). According to this process, a zone having a high water concentration is formed in the distillation column above the feed position of the mixture by feeding a mixture having a water concentration of not less than an effective amount to not more than 5% by weight (e.g., 0.5 to 4.5% by weight) and a methyl acetate concentration of 0.5 to 9% by weight (e.g., 0.5 to 8% by weight) as the mixture to the distillation column and distilling the mixture. In the zone having a high water concentration, hydrogen iodide is allowed to react with methyl acetate to produce methyl iodide and acetic acid.

A method for producing acetic acid includes subjecting an acetic acid solution to an acetic anhydride decreasing treatment. The acetic acid solution is present typically in, or downstream from, a distillation column () of acetic acid production equipment (X), includes acetic acid in a concentration of 90 mass percent or more, acetic anhydride, and water, and is in such a state that an equilibrium concentration of acetic anhydride is higher than an acetic anhydride concentration. The acetic anhydride decreasing treatment includes at least one of water concentration increasing and temperature lowering so as to bring the acetic acid solution into such a state that the equilibrium concentration of acetic anhydride is lower than the acetic anhydride concentration. The acetic acid production method is suitable for yielding a high-purity acetic acid product.

Method for producing acetic acid

A process for stably and safely producing acetic acid without increasing an internal pressure of a distillation column is provided. The process comprises () a carbonylation reaction step for allowing methanol to react with carbon monoxide; () a flash step for separating the reaction mixture into a volatile phase and a less-volatile phase; () a first distillation step for separating the volatile phase into a first overhead and a crude acetic acid stream rich in acetic acid; and () a separation step for separating at least acetaldehyde from the first overhead. The separation step () comprises () a second distillation step for distilling the first overhead while controlling an internal pressure of a distillation column provided with a pressure control unitto form a second overhead rich in acetaldehyde and methyl iodide and a bottom or lower stream, and () an extraction step for extracting acetaldehyde from the second overhead to form an extract rich in acetaldehyde and a raffinate rich in methyl iodide.

Method and apparatus for producing acetic acid

A process for separating or removing permanganate reducing compounds (PRC's) from a first mixture containing at least one PRC, methyl iodide, and water comprises the steps of: feeding the first mixture to a feed port of a distillation column, and distilling and separating the first mixture into an upper stream and a lower stream, wherein the distillation of the first mixture forms a second mixture at an upper position than the feed port, and the process further comprises the steps of: withdrawing the second mixture as the upper stream, and withdrawing the lower stream from a lower position than the feed port.

A process for producing acetic acid comprises a process comprising: (1) carbonylating methanol; (2) separating the reaction mixture into a volatile phase and a less-volatile phase; (3) distilling the volatile phase to forma first overhead rich in a lower boiling component, and an acetic acid stream rich in acetic acid; and at least one step group selected from the group consisting of the following sections (4), (9), and (15): (4) a section for separating impurities from the acetic acid stream to give purified acetic acid, (9) a section for separating the first overhead into a stream rich in acetaldehyde and a stream rich in methyl iodide, and (15) a section for absorption-treating an off-gas from the process with an absorption solvent and forming a carbon monoxide-rich stream and an acetic acid-rich stream. In this process, the concentration of oxygen in a gaseous phase of the process is controlled to less than 7% by volume and/or the concentration of oxygen in a liquid phase of the process is controlled to less than 7&#xd7;10g/g, and the formation of iodine is reduced. The process effectively reduces or prevents local corrosion of an inner wall of a process unit and/or line.

A process for producing acetic acid while efficiently separating permanganate reducing compounds (PRC's) and methyl iodide is provided. PRC's are separated or removed from a mixed composition (A) containing PRC's and methyl iodide by distilling the mixed composition in a distillation step () to form an overhead stream (A), a side-cut stream (B), and a lower stream (C). In a distillation column of the distillation step (), an extractant (e.g., water) extracting PRC's preferentially to methyl iodide is added to a concentration zone in which PRC's and methyl iodide are concentrated, and an extraction mixture falling from the concentration zone is withdrawn as the side-cut stream (B).

It is intended to provide an acetic acid production method capable of industrially advantageously separating and removing a by-product acetaldehyde in the separation step of separating a process stream into aqueous and organic phases. In the present invention, the separation step satisfies, for example, the following conditions (vi) to (viii), and at least a portion of the aqueous phase is treated in the acetaldehyde separation and removal step: (vi) acetaldehyde concentrations in the aqueous and/or organic phases are not more than 28.1 mass % and not more than 24.8 mass %, respectively; (vii) a separation temperature is not more than 70&#xb0; C.; and (viii) methyl acetate concentrations in the aqueous and/or organic phases are not more than 12.0 mass % and not more than 47.6 mass %, respectively, and/or the sum of the methyl acetate concentrations in the aqueous and organic phases is not more than 59.6 mass %.

Acetic acid is produced while inhibiting increased concentrations of hydrogen iodide and acetic acid in an acetaldehyde distillation column. A production process of acetic acid comprises a step for allowing methanol to react with carbon monoxide; a step for feeding a flasher with the reaction mixture to separate a volatile component (2A) and a low-volatile component (2B); a step for feeding a distillation column with the volatile component (2A), and separating an overhead (3A) containing methyl iodide, acetic acid, methyl acetate, water, acetaldehyde, and hydrogen iodide, and a stream (3B) containing acetic acid to collect acetic acid; and a separation step for feeding an acetaldehyde distillation column with at least part of the overhead (3A) and separating a liquid object to be treated containing the overhead (3A) into a lower boiling point component (4A) containing acetaldehyde and a higher boiling point component (4B); wherein, in the separation step, the liquid object contains methanol and/or dimethyl ether in a concentration of 0.1 to 50% by weight is subjected to distillation.

A process for producing acetic acid comprises a process comprising: (1) carbonylating methanol; (2) separating the reaction mixture into a volatile phase and a less-volatile phase; (3) distilling the volatile phase to form a first overhead rich in a lower boiling component, and an acetic acid stream rich in acetic acid; and at least one step group selected from the group consisting of the following sections (4), (9), and (15): (4) a section for separating impurities from the acetic acid stream to give purified acetic acid, (9) a section for separating the first overhead into a stream rich in acetaldehyde and a stream rich in methyl iodide, and (15) a section for absorption-treating an off-gas from the process with an absorption solvent and forming a carbon monoxide-rich stream and an acetic acid-rich stream. In this process, the concentration of oxygen in a gaseous phase of the process is controlled to less than 7% by volume and/or the concentration of oxygen in a liquid phase of the process is controlled to less than 7&#xd7;10g/g, and the formation of iodine is reduced. The process effectively reduces or prevents local corrosion of an inner wall of a process unit and/or line.

A process for removing acetaldehyde efficiently and producing high-purity acetic acid stably is provided. Methanol is allowed to continuously react with carbon monoxide in a carbonylation reactorin the presence of a catalyst system; the reaction mixture is continuously fed to a flasherto form a volatile phase (A) containing acetic acid and methyl iodide; the volatile phase (A) is continuously fed to a splitter columnto form an overhead (A) containing methyl iodide and acetaldehyde and a stream (B) containing acetic acid; the volatile phase (A) and/or the overhead (A) is cooled by a first condenser C, Cat a predetermined cooling temperature; and the noncondensed gaseous component is further cooled by a second condenser C, Cto form a concentrate having a lower temperature and a higher acetaldehyde concentration. Acetaldehyde is efficiently removed by distilling the concentrate having a high acetaldehyde concentration.

A process for producing acetic acid including an acetic acid collection step for feeding a first distillation column with a volatile component at least containing acetic acid, methyl acetate, methyl iodide, water, and hydrogen iodide. Separating a first lower boiling point component as an overhead, and collecting a first liquid stream containing acetic acid. An acetic acid purification step for feeding a second distillation column with the first liquid stream, and separating a second lower boiling point component as an overhead. Collecting a second liquid stream containing acetic acid. An alkali component is added or mixed for distilling a mixture to be treated containing the first liquid stream and the alkali component in the second distillation column. In the mixture, at least one component (A) having a boiling point lower than acetic acid. The at least one component (A) having a concentration of 0.1 to 15% by weight.

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Himeji, Japan

Hiroyuki Miura