Patent ID: 7241365
Filing Date: 2007-07-10
Classification: C07C,C22C

Abstract:
1. An apparatus for obtaining anhydrous or substantially anhydrous formic acid, at a temperature of 100° C. to 190° C., comprising i) a synthesis reactor for the preparation of methyl formate, ii) a hydrolysis reactor for the hydrolysis of the prepared methyl formate, iii) a distillation device for the separation of excess methanol and excess methyl formate from the hydrolysis mixture, iv) a distillation device for the distillation of an extract phase comprising formic acid, an extractant and some of the water, said extract phase coming from v) an extraction device for extracting the hydrolysis mixture, and vi) a distillation device for the distillative separation of a mixture comprising predominantly the extractant and formic acid coming from the distillation device iv) into anhydrous or substantially anhydrous formic acid and the extractant, where the extractant employed is a carboxamide of the general formula I where the radicals R 1 and R 2 are alkyl, cycloalkyl. aryl or aralkyl groups, or R 1 and R 2 jointly, together with the N atom, form a heterocyclic 5- or 6-membered ring, and only one of the radicals is an aryl group, and where R 3 is hydrogen or a C 1 –C 4 -alkyl group, wherein at least one device selected from the group consisting of the devices ii), iii), iv), v) and vi) is constructed partly or entirely of a material consisting essentially of low-zirconium material containing less than 1% by weight of zirconium, and wherein the surfaces of the devices i), ii), iii), iv), v), and vi) come into contact with media which contain at least 1% of formic acid and at least 1% of the extractant.