PEP Review 2004-12
Formic Acid by Kemira Process
Published: April 2004
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.