Comprehensive Characterization of Bio-Crude Oil from Hydrothermal Liquefaction of Kitchen Waste

H. Bayat, M. Dehghanizadeh, J.M. Jarvis, C.E. Brewer, U. Jena
New Mexico State University,
United States

Keywords: food waste, hydrothermal liquefaction, high resolution FT-ICR MS, FAME analysis, bio-crude oil

Summary:

Food waste (both pre-consumer and post-consumer kitchen fractions) is a significant fraction of municipal solid waste. Increasing food waste generation (1.6 billion tons per year) due to urban and industrial development has prompted researchers to pursue alternative waste management methods. Energy valorization of food waste is one such alternative method that can reduce the environmental impacts resulting from landfills and reduce global reliance on crude oil for liquid fuels. Hydrothermal liquefaction (HTL) is a technique for converting wet biomass like food waste into an energy-dense bio-crude oil product that can be hydroprocessed to liquid transportation fuels. In order to find the appropriate approach for bio-crude oil upgrading to improve its properties as a feedstock for liquid transportation fuel blends and specialty chemicals, comprehensive chemical characterization of the bio-crude oil is essential. In this study, HTL of kitchen waste from a New Mexico State University (NMSU) dining hall was performed at 240-295 °C for 0-60 min. Several complementary analytical methods were used to characterize the produced bio-crude oils in different operating condition, including fatty acid methyl ester (FAME) analysis by gas chromatography with flame ionization detection (GC-FID), elemental analysis (CHNS), Fourier transform infrared spectroscopy (FT-IR), and for an ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectroscopy (FT-ICR MS). The FT-ICR MS indicated that O3-6 containing compounds were the most abundant heteroatoms class in bio-crude oil derived at low temperature (240 °C), while the nitrogen heteroatom classes were dominant at the higher temperature (295 °C). The total FAME content of kitchen waste bio-crude was 15-37wt.%, which the most abundant FAMEs were palmitic acid (C16:0), palmitoleic acid (C16:1), stearic acid (C18:0) and polyunsaturated fatty acids (C18:3n:3, C18:3n:6 and etc.). This presentation will briefly discuss different hydroprocessing options for upgrading the above bio-crude oil.