Abstract. is one of the main species causing green tide. In this study, hydrothermal liquefaction of E. was carried out, and the operating conditions were optimized using response surface methodology. The results indicated that hydrothermal liquefaction at 295°C with 14% solids content produced the highest bio-oil yield of 18.4%. The higher heating value was 31.9 to 34.2 MJ kg-1 and almost monotonically increased with increasing reaction temperature. The energy recovery, carbon recovery, and nitrogen recovery of bio-crude were mainly dependent on yield rather than elemental composition as the investigated variables changed. The chemical composition of bio-crude was characterized by Fourier transform ion cyclotron resonance mass spectrometry. The acidic O-containing compounds were mainly O2 class compounds, namely hexadecanoic acid and octadecanoic acid. The basic N-containing compounds were mainly nitrogenous heterocyclic compounds with carbon numbers of 20 to 40 and high degrees of unsaturation. Keywords: Bio-crude, FT-ICR MS, Hydrothermal liquefaction, Response surface methodology.
Abstract. In this study, catalytic hydrothermal liquefaction (HTL) of with aqueous phase recirculation (APR) was tested in order to improve bio-crude yield and reduce catalyst dosage. Bio-crude yields of 17.0% and 18.5% were obtained at 300°C in 30 min of non-catalytic HTL and catalytic HTL with 5.0% NaOH, respectively. Determination of alkali metals showed that 76.7% of the Na was recovered in the aqueous phase, indicating that APR provided the possibility for catalyst recycling. Bio-crude yields were increased to 20.0% and 22.7% when performing APR for non-catalytic and catalytic HTL, respectively. To investigate the effects of recycled catalyst and volatile aqueous products (VAPs), a different APR experiment with VAPs removal for catalytic HTL was conducted, and a bio-crude yield of 17.8% was achieved. It was concluded that bio-crude yield increased with APR, mainly due to the effects of VAPs. Keywords: Alkali metal, Aqueous phase recirculation, Hydrothermal liquefaction.
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