(508b) De-Oxygenation of Bio-Oil Via Electrocatalysis

Bio-oil, a pyrolysis oil, has been recognized as a possible renewable energy source to supplement declining fossil fuel sources. Bio-oil offers sustainability, reduction of greenhouse gas emissions, and regional development. However, higher oxygen content (> 35%) in raw bio-oil is problematic because of reduced efficiency of energy recovery from the oil. Therefore, this research studies an upgrading approach involving the passage of electric fields through bio-oil to catalyze reduction reactions to reduce oxygenated hydrocarbons into higher energy hydrocarbons. This electro-catalytic process has the potential to overcome limitations of the solid catalytic method such as catalyst coking as well as high temperature and pressure operating conditions. Experiments were conducted in a custom designed electrolytic cell (E-cell) within which the complementary oxidation and reduction reactions occur at the electrode surface in the presence of the electric field. Chemical conversion via three types of electrocatalytic metals (Steel, Aluminum, and Nickel) and two different electric field strengths (5/3 and 200/2 [VDC/cm]) were studied. Two membrane separating the electrode chambers were compared: (1) an ion-selective semi-permeable nafion membrane and (2) dialysis membrane 10,000 MWCO. Experiment times of 30 min, 2 hr, and 5 hr were investigated. In addition, modifications of bio-oil solution were attempted to increase operating current within E-cell by addition of a metal catalyst, pH adjustment via NaOH, and electrolyte addition via NaCl. Temperature, pH, and current were monitored in real time via a LabVIEW/ National Instruments Data Acquisition system. Elemental, FTIR and GC/MS analysis were conducted to determine changes in Bio-oil composition. Electrocatalytic reactions with steel at 200 VDC for 5 hours showed the most significant oxygen reduction with 10% O (anode) and 27% O (cathode) of the original oxygen content. Furthermore, NaOH and NaCl bio-oil solutions achieved increased current (and thus reactions) between cathode and anode. FTIR and GC/MS results demonstrate that aliphatic ketones were converted to oxygen-reduced forms secondary aliphatic alcohols and that highly oxygenated hydrocarbons were converted to less oxygenated hydrocarbons. This process provides an alternative approach to in situ bio-oil upgrading.