Binary Transition Metal Oxide (BTMO) Nanoparticles for Hydrothermal Liquefaction of Pinewood

A. Shende, V. Amar, R. Shende
South Dakota School of Mines and Technology,
United States

Keywords: BTMO, pinewood, hydrothermal liquefaction, biofuel, value added co-products

Summary:

Iron based binary transition metal oxide (BTMO) nanoparticles were synthesized using controlled precipitation and sol-gel methods. For the latter, a non-ionic surfactant was used in the concentration range of 5-30 wt% along with the metal oxide precursors. The powdered BTMO material obtained after calcination was analyzed using x-ray diffraction, scanning electron microscopy and BET surface area analyzer. BTMO nanoparticles were utilized for hydrothermal liquefaction of pinewood in the temperature range of 250-325oC without any pretreatment. The aqueous phase recovered after hydrothermal liquefaction was characterized by HPLC and GC-MS, which indicated the presence of alcohols, esters, ethers, ketones, phenols, and carboxylic acids. Among the carboxylic acids, lactic acid was considered as value added co-product that has application in making bio-degradable polymer such as polylactide (PLA). The aqueous waste stream was then wet oxidized using a catalytic material, which showed enrichment by 2-3 fold of the lactic acid. Recovered biochar solid was further extracted with acetone/ethanol to obtain bio-oil, which was subsequently analyzed for elemental composition, acid number, and energy density. The higher heating value (HHV) of the oil was found to be approx. 35 MJ/kg. The biochar was sonicated to convert into submicron particles and graphitized in an inert atmosphere, and analyzed by BET surface area analyzer. The carbon obtained has utility as a soil amendment material, filtration media, and in supercapacitors. Detailed synthesis methods for BTMO, hydrothermal liquefaction process using BTMO, yields of different products and coproducts during wet oxidation, and HHV of oils recovered will be presented.