(403f) Electrochemical Bio-Oil Stabilization As an Alternative for Distributed Processing of Biomass

Authors: 
Diaz, L. A., Idaho National Laboratory
Lister, T., Idaho National Laboratory
Padmaperuma, A. B., Pacific Northwest National Laboratory
Lilga, M. A., Pacific Northwest National Laboratory
The conversion of biomass to value-added chemicals and liquid fuels is a developing alternative to fossil sources [1]. Bio-oil, which can be obtained from thermal breakdown of forest and agricultural biomass, can be produced near the material source. The distributed production of bio-oil allows the densification of the biomass energy and could reduce the transportation and production costs. However, compared with fossil hydrocarbon sources bio-oil is a chemically unstable micro emulsion that cannot be fractionated [1, 2]. The high concentration of oxygenated compounds (hydroxyaldehydes, hydroxyketones, sugars, carboxylic acids, and phenols) reduces the storage and temperature stability of the bio-oil and results in 50% lower calorific value when compared to hydrocarbon fuels [1, 3, 4]. The typical route to removing oxygen involves a process called hydrodeoxygenation (HDO). Typical HDO conditions (425â?¦C and 2000 psi H2 pressure) promote condensation reactions leading to the formation of coke. A multi-step hydrotreatment process, which include low temperature (140â?¦C) hydroprocessing stabilization under high H2 pressure (1200 psi H2 pressure), reduce the reactivity for HDO [5, 6]. In distributed production mild conditions are desired to reduce capital requirements at remote sites near biomass sources.
In this work an electrochemical process has been investigated as a low temperature alternative for the electrochemical reduction (ECR) and stabilization of bio-oil. The process attempts to reduce site requirements for hydrogen and achieve even milder conditions than used for existing catalytic stabilization. A polymer electrolyte membrane (PEM) configuration allows the processing of the complete bio-oil product without the addition of supporting electrolyte. While work to this point has focused on use of PEM cells employing cation exchange membranes, future work will attempt to use anion exchange membranes where current would be carried by anions of small acid compounds (acetate and formate). This configuration could simultaneously reduce reactivity of oil and also remove small acid molecules that contribute acidic content and consume hydrogen in downstream processes in production of low value gases. Description of the electro-catalytic systems and results obtained with different transition metal catalysts will be presented.
References
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