Hydrothermal liquefaction of olive oil residues

© 2021 Elsevier B.V.Hydrothermal liquefaction (HTL) of olive oil residues was conducted at various temperatures (250, 270, 300 and 330 °C) and residence times (5, 15, 30, and 60 min). The effect of metal chlorides (AlCl3 and SnCl2) on product yields and compositions was investigated under optimum conditions (300 °C for 15 min). Bio-oil and solid residue yields from the non-catalytic run were 30.8 and 31.8 wt%, respectively. Use of metal chlorides led to decreased bio-oil yields and increased solid residue yields. Experiments were also carried out using methanol, with and without catalysts, and under identical conditions. The bio-oil yield from the non-catalytic supercritical methanol liquefaction (SCMEL) was 33.5 wt%, increasing to 40.3 wt% with AlCl3, however, SnCl2 had almost no effect on bio-oil yield. The heating values of bio-oils from HTL runs were higher than those of corresponding SCMEL runs, and the highest heating value of bio-oil (34 MJ/kg) was obtained with AlCl3. Phenols and ketones were major bio-oil constituents in the HTL runs, whereas esters were the most abundant compounds in bio-oils from SCMEL runs

Hydrothermal carbonization of lignocellulosic biomass and effects of combined Lewis and Bronsted acid catalysts

This study is the first to investigate the effect of combined Lewis and Bronsted acid catalysts on the hydrothermal carbonization of fir wood samples; here, hydrothermal carbonization of fir wood-with and without catalyst-was performed. In non-catalytic runs, the effects of temperature and residence time on hydrochar yields were investigated; temperature significantly affected hydrochar yields, whereas residence time had very little effect. A gradual increase in temperature resulted in a decrease in hydrochar yields while increasing the carbon content of hydrochars. At all tested temperatures, the use of a catalyst led to a decrease in hydrochar yields. The highest heating value of 29.12 MJ kg(-1) was obtained at the highest temperature (275 degrees C) and the longest residence time (24 h). The use of catalysts slightly decreased the heating values. The hydrochars were mainly in the class of lignite coal; hydrochar obtained at 275 degrees C and a residence time of 12 h-either with or without catalysts-was classified as bituminous coal. Irregular carbon sphere formation was observed at all temperatures tested in the catalytic runs; however, no carbon spheres were observed in the non-catalytic runs. XRD patterns of hydrochars from the non-catalytic runs were similar for temperatures of 225, 250 and 275 degrees C; the peak observed at 2 theta of 22 degrees broadened after HTC processing. In the catalytic runs, two new peaks at 2 theta of 38 degrees and 49 degrees were observed, in addition to broadened peaks (2 theta = 22 degrees). The use of catalysts led to the formation of the secondary char