Material for a facility for the production of anhydrous formic acid

A process for obtaining anhydrous or substantially anhydrous formic acid, in which, in a plant,

• α) methyl formate is subjected to hydrolysis,
• β) methanol and excess methyl formate are distilled off from the resultant hydrolysis mixture,
• χ) the bottom product from distillation β), comprising formic acid and water, is extracted in a liquid-liquid extraction with an extractant which principally takes up the formic acid, and the extractant employed here is a carboxamide of the general formula I
• 5
• where the radicals R1 and R2 are alkyl, cycloalkyl, aryl or aralkyl groups, or R1 and R2 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 R3 is hydrogen or a C1-C4-alkyl group,
• δ) the resultant extract phase, comprising formic acid, extractant and some of the water, is subjected to distillation,
• ε) the top product obtained in this distillation, which comprises water and some of the formic acid, is fed back into the lower part of the distillation device in step β),
• 100 ) the bottom product from distillation step ε), which comprises predominantly extractant and formic acid, is separated by distillation into anhydrous or substantially anhydrous formic acid and the extractant, and
• γ) the extractant leaving step φ) is fed back into the process,
• characterized in that one or more plant parts which come into contact with formic acid and with extractant are constructed partly or completely of a low-zirconium material selected from the group consisting of the material classes titanium/palladium alloys, chromium-, molybdenum- and/or tungsten-containing nickel-based materials and molybdenum-containing, highly alloyed, austenitic chromium/nickel special steels,
• where the chromium-, molybdenum- and/or tungsten-containing nickel-based materials contain 14 to 24% by weight of Cr, 8 to 17% by weight of Mo and/or 3 to 5% by weight of W, max. 25% by weight of other elements and Ni as rest,
• the molybdenum-containing, highly alloyed, austenitic chromium/nickel special steels contain 18 to 30% by weight of Cr, 12 to 40% by weight of Ni, 3 to 7% by weight of Mo, max. 3% by weight of Cu, max. 0.05% by weight of C, max. 25% by weight of other elements and Fe as rest, and
• the temperatures during the process are on average 75° C.