Acetic acid production method incorporating at least one metal salt as a catalyst stabilizer

Abstract

Processes for the production of acetic acid by carbonylation of methanol, and reactive derivatives thereof, in a reaction mixture using a rhodium-based catalyst system with at least one metal salt catalyst stabilizer selected from the group of ruthenium salts, tin salts, and mixtures thereof are provided. The metal salt stabilizers minimize precipitation of the rhodium metal during recovery of the acetic acid product, particularly in flasher units in an acetic acid recovery scheme. Stability of the rhodium metal is achieved even when the acetic acid is produced in low water content reaction mixtures in the presence of an iodide salt co-promoter at a concentration that generated an iodide ion concentration of greater than about 3 wt.% of the reaction mixture. The stabilizing metal salts may be present in the reaction mixtures for the production of acetic acid at molar concentrations of metal to rhodium of about 0.1: 1 to about 20: 1. The stabilizing metal salt may be combined with other catalyst stabilizers as well as catalyst promoters.