Catalytic and electrocatalytic oxidation of ethanol over a La0.6Sr0.4Co0.8Fe0.2O3 perovskite-type catalyst

Abstract

The catalytic and electrocatalytic behavior of the perovskite-type La0.6Sr0.4Co0.8Fe0.2O3 catalyst was investigated during ethanol oxidation. Experiments were carried out at atmospheric pressure in a fully yttria-stabilized zirconia (YSZ) continuously stirred tank reactor (CSTR) in the temperature range between 300 and 750 degreesC and fuel-rich reactant mixtures (P-O2 = 2 kPa, P-ethanol = 13.5 kPa). It was round that oxygen-nitrogen streams saturated with ethanol (at room temperature and atmospheric pressure) lead mainly to the formation of formaldehyde and acetaldehyde. For the aforementioned reaction conditions, gas-phase oxidation becomes predominant at temperatures higher than 650 degreesC and in combination with heterogeneous phenomena leads to 100% ethanol conversion and high acetaldehyde yields (75%) at about 750 degreesC. The electrochemical supply of oxygen anions mainly affects the formation rates of CO and CO,. Due to the high operating temperatures, direct electrocatalysis and homogeneous reactions, more than NEMCA (Lambda (max) = 3), affect the overall kinetic behavior. (C) 2000 Elsevier Science B.V. All rights reserved.