The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 08, 1999
Filed:
Jul. 28, 1995
Yasuyuki Sakakura, Yokkaichi, JP;
Masahiko Yamagishi, Yokkaichi, JP;
Hirochika Hosaka, Yokkaichi, JP;
Mitsubishi Chemical Corp., Tokyo, JP;
Abstract
In a process for producing acrylic acid, wherein propylene and/or acrolein is catalytically oxidized with molecular oxygen in a vapor phase and the gas resulting from the oxidation is cooled and/or absorbed in water to form a crude aqueous acrylic acid, followed by azeotropic distillation to remove the water with an entrainer of a boiling point of no higher than 130.degree. C. on the crude aqueous acrylic acid which may have, upon necessity, undergone removal of aldehydes contained therein to produce acrylic acid purified in that the crude aqueous acrylic acid is substantially dehydrated, the improvement which comprises conducting the azeotropic distillation under such conditions that concentrations of the entrainer and water in the bottom product of the azeotropic distillation are from 5% to 30% by weight and no higher than 0.5% by weight, respectively, where the theoretical number of plates in the azeotropic distillation column for dehydration used and that in the distillation column for separating acetic acid used are preferably from 5 to 20. Highly-purified acrylic acid can thus be obtained from the crude aqueous acrylic acid without causing unfavorable polymerization of acrylic acid.