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:
Mar. 28, 1978
Filed:
May. 05, 1976
Mitsui Toatsu Chemicals, Inc., Tokyo, JA;
Abstract
A process for continuously producing anhydrous sodium dithionite in the form of large granules which comprises reacting formic acid, sodium formate, sodium hydroxide and sulfurous acid anhydride in hydrous methanol using a multi-stage reaction apparatus, wherein all the required amounts of the formic acid or sodium formate, sodium hydroxide, methanol and water, and at least 60%, based on the required amount, of sulfurous acid anhydride are introduced into a first reactor, and the residence time in the first reactor is adjusted so that the conversion of the sulfurous acid anhydride to anhydrous sodium dithionite is within the range of 25 to 50%; the remainder of the sulfurous acid anhydride is introduced into a second reactor; and the reaction temperature in any given reactor is maintained at a point not lower than the reaction temperature in the immediately preceding reactor.