[HARAMAKI HIDEFUMI, SAKAMOTO KAZUHIKO, UEOKA MASATOSHI, BABA MASAO, AKAZAWA YOHJI] JP

[Ogata, Yousuke, Takashima, Takehiro, Dodo, Osamu, Haramaki, Hidefumi] 1-1, Koraibashi, 4-chome, Chuo-ku, Osaka-shi, Osaka 541, JP

[HARAMAKI HIDEFUMI]

[HARAMAKI HIDEFUMI, SAKAMOTO KAZUHIKO, VEOKA MASATOSHI, AKAZAWA YOHJI, BABA MASAO]

[MITSUMOTO TETSUJI, NISHIMURA TAKESHI, NAKAHARA HITOSHI, HARAMAKI HIDEFUMI] PROBLEM TO BE SOLVED: To provide a method for controlling the polymerization of an easily polymerizable substance when the substance is purified by using a distillation column. SOLUTION: In a method for preventing the polymerization of the substance, in the purification of the substance, (a) a column having at least one tray fixed directly to a support ring with the use of bolts and nuts and/or (b) at least one tray fixed to the support ring with the use of a vertical clamp or the distillation column having a liquid spray collision plate in the lower part are used.

[HARAMAKI HIDEFUMI, MATSUI MANABU] JP

[Tetsuji Mitsumoto, Takeshi Nishimura, Sei Nakahara, Hidefumi Haramaki] JP Osaka This invention resides in providing a method for the prevention of possible polymerization of the easily polymerizable substance during the purification thereof by a column provided with (a) at least one tray directly fixed to a support ring with a bolt and a nut and/or (b) at least one tray fixed to a support ring with a vertical clamp or a distillation column provided in the lower part thereof with a splash collision plate.

[MATSUMOTO YUKIHIRO, NISHIMURA TAKESHI, SAKAMOTO KAZUHIKO, HARAMAKI HIDEFUMI] In a method for producing acrylic acid by the steps of a reaction of catalytic gas phase oxidation, absorbing the acrylic acid with an absorbent, and dehydrating the acrylic acid-containing aqueous solution, the method is characterized that the step of dehydration comprises adding and an azeotropic solvent, distilling the resultant mixture, and adjusting the acrylic acid concentration at the top of the column in the range of 0.06-0.80 wt. %, thereby preventing the bottoms of the azeotropic dehydration column from substantially containing the azeotropic solvent and water. As results, the acrylic acid is kept from forming a polymer in any of the distillation columns involved in the production, and effective utilization of acrylic acid.

[HARAMAKI HIDEFUMI, SAKAMOTO KAZUHIKO, UEOKA MASATOSHI, AKAZAWA YOHJI, BABA MASAO]

[HARAMAKI HIDEFUMI, DODO OSAMU, TAKAMURA MAMORU] JP