Selective Production of Acetic Acid via Catalytic Fast Pyrolysis of Hexoses over Potassium Salts

Abstract

Glucose and fructose are widely available and renewable resources. They were used to prepare acetic acid (AA) under the catalysis of potassium acetate (KAc) by thermogravimetric analysis (TGA) and pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). The TGA result showed that the KAc addition lowered the glucose’s thermal decomposition temperatures (about 30 °C for initial decomposition temperature and 40 °C for maximum mass loss rate temperature), implying its promotion of glucose’s decomposition. The Py-GC/MS tests illustrated that the KAc addition significantly altered the composition and distribution of hexose pyrolysis products. The maximum yield of AA was 52.1% for the in situ catalytic pyrolysis of glucose/KAc (1:0.25 wt/wt) mixtures at 350 °C for 30 s. Under the same conditions, the AA yield obtained from fructose was 48% and it increased with the increasing amount of KAc. When the ratio reached to 1:1, the yield was 53.6%. In comparison, a study of in situ and on-line catalytic methods showed that KAc can not only catalyze the primary cracking of glucose, but also catalyze the cracking of a secondary pyrolysis stream. KAc plays roles in both physical heat transfer and chemical catalysis.