Investigation of the electrochemical characteristics of gaseous products derived from low-temperature molten nitrate salt pyrolysis of biomass

To tackle the issues of poor thermal conductivity and low-value products in biomass pyrolysis, our previous research investigated molten nitrates as a heat transfer medium, which enhanced efficiency and yielded high-value gases at 350 °C. This study investigates the integration of biomass nitrate pyrolysis with solid oxide fuel cell (SOFC) technology. Experimental results demonstrate stable electrochemical conversion of pyrolysis gas in SOFC, achieving a peak power density of about 100 mW/cm 2 . Following 10,000 s of discharge cycling, no carbon deposition was observed and voltage decreased by only 0.57 %. Nitrogen oxide emissions were analyzed, revealing the role of nitric oxide in the electrochemical conversion process. The primary source of nitrogen oxides stemmed from the oxidation of anions with biomass, particularly NO 2 – . Elevated temperatures promoted nitrogen oxide formation, with cellulose contributing significantly due to reducing sugars from its decomposition. Hemicellulose produced fewer reducing sugars, and lignin, with its predominant aromatic structure, was less reactive. At typical SOFC temperatures, NO decomposed to produce O 2 , facilitating redox reactions with reforming gas, enhancing the anode reaction rate and reducing SOFC polarization resistance by about 1.3 Ω upon NO introduction. This coupling exhibited a denitrification potential, achieving a NO removal rate of arround 75 % after two cycles. These findings facilitate the high-value utilization of biomass nitrate pyrolysis gas and the removal of nitrogen-containing component.