Hydrothermal liquefaction of Moroccan two-phase olive mill waste (alperujo): Parametric study and products characterizations

• Published in: Industrial crops and products 2023-12, Vol.205, p.117519, Article 117519
• Main Authors: Dahdouh, Akram, Le Brech, Yann, Khay, Ismail, El Maakoul, Anas, Bakhouya, Mohamed
• Format: Article
• Language: English
• Subjects: Bio-oil; Chemical Sciences; Hydrochar; Hydrothermal liquefaction; Thermochemical processes; Two-phase olive mill wastes
• ISSN: 0926-6690; 1872-633X
• DOI: 10.1016/j.indcrop.2023.117519

The primary objective of this study is to investigate the hydrothermal liquefaction of two-phase olive mill waste (TPOMW). Consequently, a parametric study of the two-phase olive mill waste hydrothermal liquefaction was conducted using a batch reactor to screen different experimental operating conditions. Experiments were conducted at different temperatures: 260, 280, and 300 °C, dry-matter/water ratios: 0.05, 0.10, and 0.15, and residence times: 0 (no isotherm step), 30, 45, and 60 min. The product (gases, bio-oils, hydrochar) yields, global carbon mass balances, elemental composition (CHNS-O), and energy yield obtained were evaluated for each experimental condition. The operating condition at 280 °C with 0.15 dry-matter/water ratio and no isotherm step resulted in the maximum energy yield of the process (87%). Under these conditions, the bio-oil and hydrochar yields were equal to 37.2 wt% and 22.6 wt% of initial dry matter, respectively. Analysis of the products showed that the produced bio-oil (30.8–32.1 MJ/kg) and hydrochar (27.7–30.6 MJ/kg) presented higher values than lignite and coal, thus, these products can potentially be used for energetic insights. In terms of BO composition, FT-IR analysis exhibited the presence of some compounds such as carboxylic acids phenols, and esters. GC-FID/MS analysis showed that the produced bio-oils are rich in phenolic compounds, oleic acid, hexadecanoic acid, fatty acid methyl ester, and fatty acid ethyl ester, which is in accordance with FT-IR analysis. •Two-phase olive mill waste hydrothermal liquefaction was performed at different temperatures (260-300 °C), residence times (0- 60 min), and dry-matter/water ratios (0.05-0.15).•Bio-oil yield reached a maximum value of 37.2 wt% of initial dry biomass (5 °C/min, 0 min at 280 °C and 15% of dry-matter).•Higher heating values reached 32.1MJ/kg for bio-oils and 30.6 MJ/kg for hydrochars.•Bio-oils were mainly composed of phenolic compounds, oleic acid, hexadecanoic acid, fatty acid methyl ester, and fatty acid ethyl ester.