Nippon Shokubai Co., Ltd.

Kunihiko Suzuki

Kazuhiko Sakamoto

Koji Ueno

Yukihiro Matsumoto

Takeshi Nishimura

Sei Nakahara

Harunori Hirao

Yoshitake Ishii

Satoshi Nakagawa

Masatsugu Kitaura

Kei Hamamoto

Takashi Sugimoto

Atsushi Sugano

[PROBLEM] There is provided a method for regenerating a filter, by which deterioration of the color tone of purified acrylic acid can be prevented. [SOLUTION] There is provided a method for regenerating a filter which has been used in a filtration step in the process for producing an acrylic acid, comprising a step (A) wherein the filter is washed with an aqueous alkaline solution, a step (B) wherein the filter is washed with water after the step (A) , and a step (C) wherein the filter is brought into contact with the acrylic acid for regeneration for at least one hour after the step (B).

Method for regenerating filter

A process for producing (meth)acrylic acid of the present invention comprises the steps in the following order: a crystallization step of supplying a cooling medium cooled by a heat source device to a crystallizer to obtain a (meth)acrylic acid crystal from a crude (meth)acrylic acid solution; an adjustment step of returning the cooling medium discharged from the crystallizer to the crystallizer without cooling; a sweating step of supplying a heating medium to the crystallizer to partially melt the (meth)acrylic acid crystal, thereby obtaining a melted liquid, and discharging the melted liquid from the crystallizer; and a melting step of supplying the heating medium to the crystallizer to melt the (meth)acrylic acid crystal, thereby obtaining purified (meth)acrylic acid. According to the present invention, purified (meth)acrylic acid with high purity can be obtained.

Process for producing (meth) acrylic acid

In the reaction of catalytic gas phase oxidation induced by the supply of at least a raw material to be oxidized and a molecular oxygen-containing gas to a reactor for catalytic gas phase oxidation, a method for starting up the reactor for catalytic gas phase oxidation is disclosed which is characterized by causing the raw material and the molecular oxygen-containing gas to pass a range in which the concentration of the raw material is less than the lower explosion limit of the raw material and the concentration of oxygen is not less than the limiting oxygen concentration, but excluding the concentration of the raw material of 0 vol. %. The method enables the reactor to be started up economically and safely by avoiding the explosion range induced by the composition of a raw material and a molecular oxygen-containing gas supplied to the reactor and decreasing the amount of a diluting gas to be supplied.

Method for starting up reactor

An apparatus for the preparation and supply of a polymerization inhibitor which constantly effects stable supply of a polymerization inhibitor solution adjusted to a prescribed concentration and enables a compound handled at the next step to be prevented from polymerization is provided. The apparatus for the preparation and supply of a polymerization inhibitor has at least two tanks and a stirring device, a liquid level detector, a polymerization inhibitor input port, a concentration-adjusting liquid input port, and a polymerization inhibitor solution feed opening, each being installed in at least one of said tanks.

Apparatus and method for preparation and supply of polymerization inhibitor

Growing community of inventors

Hyogo, Japan

Kunihiko Suzuki