MASSIMO BARBIERI*, FLAVIO MANENTI
*Corresponding author
Politecnico di Milano, Milan, Italy

Abstract

This work presents an overview of the patent activity and filing trends on acetic acid industrial processes. Data were obtained with Orbit Intelligence patent database, using both keywords and classification codes (IPC, CPC, and C-sets). The complete search strategy has been reported. Data analysis reveals that methanol carbonylation is the most patented process, while fermentation methods are the most attractive technologies. The filing of new patent applications shows a decreasing trend in the period comprising 2016 and 2020 for all technologies

INTRODUCTION
Acetic acid is considered one of the most important chemical products, with about 16 Mt/y production in 2020 and a positive forecast for the next lustrum (2022-2026). It is mainly used to produce cellulose acetate, vinyl and polyvinyl acetate, acetic anhydride, terephthalic acid and synthetic fibers (1).

The main processes to synthetize acetic acid are the methanol carbonylation, the vapor phase oxidation of ethane and ethylene, the liquid phase oxidation of n-butane and naphtha, the oxidation of acetaldehyde, the isomerization of methyl formate and the anaerobic fermentation (2).

Methanol carbonylation is the most used industrial method, which covers 75% of the market, while fermentation processes, although desirable from an ecological point of view, are economically less convenient, due to the high energy consumption in the phases of separation and purification.

Methanol carbonylation is a moderately exothermic reaction and is thermodynamically favored by low temperatures (150° - 200° C) and pressures of 30 - 60 bar.

The catalysts used in the vario ...