In the production of formic acid without coproducts, most of the world’s
formic acid is obtained by a two-step procedure: formation of methyl formate
by the carbonylation of methanol, followed by hydrolysis of the ester and
rectification of the products to produce formic acid. Although seemingly straightforward,
the hydrolysis step is complex enough to have initiated many competing technologies.
These processes are associated with companies such as Kemira and BASF. These
processes generate an aqueous formic acid (85%-99%) product. This report assumes
85% formic acid.
Kemira’s hydrolysis uses a low water to methyl formate ratio, thus the
conversion is low. Unconverted methyl formate is then adiabatically flashed
in a proprietary step along with methanol. The flash is said to minimize the
extent of back-esterification. In recent years, effort has been invested on
improving the conversion (and also the energy consumption of water separation
by distillation). In the method, methyl formate is fed into an ion exchange
bed, in which the hydrolysis into formic acid and methanol and the separation
of formic acid from methanol take place simultaneously by means of the catalytic
and adsorbent properties of the solid ion exchange material in a chromatographic
hydrolysis reactor. In this review, we evaluate Kemira’s new hydrolysis
approach. We also provide an update of the economics of the old Kemira process
for comparison.
by: Noni Suk-Chin Lim
