Process for the preparation of formic acid

摘要

In a process for the hydrolysis of methyl formate with water at a molar ratio of 1:1 to 1:3 by heating in the presence of a catalyst of the acid type with a continuous method of operation, the hydrolysis is carried out in a vertical two-phase column reactor at atmospheric pressure with introduction of water into the upper zone of the reactor, which is packed with a strongly basic sulphocation exchanger based on a copolymer of styrene and 2 to 8% by weight of divinylbenzene as the catalyst, and of methyl formate into the lower zone of the reactor in countercurrent. In the upper zone of the reactor, a temperature of 60 to 100 DEG C is maintained and at the same time a mixture of unreacted methyl formate and methanol formed is led off from the upper zone. In the lower zone, the hydrolysis is carried out autocatalytically in the presence of the formic acid from the upper zone at a pH of less than 1.9 and a temperature of 100 to 107 DEG C. In this way, 70 to 99% of the methanol formed is derived from the upper zone of the reactor and 1 to 30% methanol from the lower zone of the reactor.