Acetic acid removal from bio-oil on alumina-supported CaO and/or Ag catalysts

Abstract

Acetic acid removal from bio-oil by catalytic processes was investigated over alumina-supported calcium oxide and silver catalysts. A 20 wt.% CaO supported on γ-Al2O3 system (CaO-Al) was prepared by precipitation of CaCO3 followed by calcination to obtain the supported oxide. A 10 wt.% Ag catalyst was prepared by impregnation on CaO-Al as support (Ag/CaO-Al). The conversion of acetic acid was tested in batch micro-reactors, with the purpose of screening the reaction conditions. Both CaO-Al and Ag/CaO-Al were active for the reaction, with the contribution of the metal phase increasing the conversion with respect to CaO-Al (75.7% vs. 58% at 200 °C). The Ag/CaO-Al catalyst was also tested in a batch reactor at two pressures, achieving a conversion of acetic acid of 97.5% at the lowest pressure (280 kPa). Based on the results, it is postulated that multiple pathways (catalytic decarboxylation, neutralization and ketonization) are responsible for acetic acid conversion.