Oxidation of Monoethylene Glycol to Glycolic Acid with Gold-Based Catalyst and Glycolic Acid Isolation by Electrodialysis

Abstract

In this work, a highly selective and active gold-based catalyst for the oxidation of high concentrated monoethylene glycol (MEG) in aqueous solution (3 M, 20 wt%) is described. High glycolic acid (GA) selectivity was achieved under mild reaction conditions. The optimization of the catalyst composition and of the reaction conditions for the oxidation of MEG in semi-batch mode under alkaline conditions led to a GA yield of >80% with a GA selectivity of about 90% in short reaction time. The bimetallic catalyst 0.1 wt% AuPt (9:1)/CeO2 showed very high activity (>2000 mmolMEG/gmetalmin) in the oxidation of MEG and, contrary to other studies, an extremely high educt to metal mole ratio of >25,000 was used. Additionally, the gold–platinum catalyst showed a high GA selectivity over more than 10 runs. A very efficient and highly selective process for the GA production from MEG under industrial relevant reaction conditions was established. In order to obtain a GA solution with high purity for the subsequent polymerization, the received reaction solution containing sodium glycolate, unreacted MEG and sodium oxalate is purified by a novel down-stream process via electrodialysis. The overall GA yield of the process exceeds 90% as unreacted MEG can be recycled.

Catalytic upgrading of PET to acid by engineering bimetallic AuCu/CNT catalyst

“…17 Currently, various bimetallic and multimetallic catalysts have been widely used, such as Au-Pt, Au-Pd and Pt-Fe catalysts, which exhibit synergistic effects in accelerating oxidation rates and are more active and selective than single metal catalysts, while also being less prone to deactivation. 18 Shi et al 19 investigated the application of highly active and selective Pt-Fe alloy catalysts prepared on CeO 2 supports in the water-phase oxidation of EG to produce glycolic acid. The results showed that Pt-Fe nanoparticles exhibited a highly alloyed state with a face-centered cubic crystal structure and PtO/FeO chemical states.…”

“…On the other hand, the deprotonation of H 2 O cannot easily provide OH* 17 . Currently, various bimetallic and multimetallic catalysts have been widely used, such as Au–Pt, Au–Pd and Pt–Fe catalysts, which exhibit synergistic effects in accelerating oxidation rates and are more active and selective than single metal catalysts, while also being less prone to deactivation 18 …”