Oil extracted from spent coffee grounds for bio-hydrotreated diesel production
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Author list: Phimsen S., Kiatkittipong W., Yamada H., Tagawa T., Kiatkittipong K., Laosiripojana N., Assabumrungrat S.
Publisher: Elsevier
Publication year: 2016
Journal: Energy Conversion and Management (0196-8904)
Volume number: 126
Start page: 1028
End page: 1036
Number of pages: 9
ISSN: 0196-8904
Languages: English-Great Britain (EN-GB)
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Abstract
Oil extracted from spent coffee grounds is utilized as a renewable source for bio-hydrotreated fuel production. In the present work, oil yield up to 13% can be obtained by Soxhlet extraction with hexane as a solvent. As the extracted oil contained high content of free fatty acids (6.14%), therefore one step alkali-catalyzed for ester based biodiesel production is impractical. Hydrotreating of extracted oil was performed over two catalysts i.e. NiMo/γ-Al2O3 and Pd/C with different operating parameters i.e. reaction time, operating temperature, and H2/oil. It was found that the reaction time of 2 h and the reaction temperature of 400 °C are favorable operating conditions. The liquid products mostly consisted of n-pentadecane and n-heptadecane, which contain one carbon atom shorter than the corresponding fatty acid (Cn−1) i.e. palmitic and stearic acid, respectively. Unfavorable cracking of diesel product is pronounced at high temperature and prolonged reaction time. In addition, although increased H2/oil promoted overall reaction and hydrodeoxygenation activity (Cn−1/Cn decreased) for both catalysts, hydrocracking is enhanced over Pd/C, leading to significant increase in gasoline yield. Moreover, Pd/C gave higher olefin content in liquid product (22.3 wt%) than NiMo/γ-Al2O3 (4.8 wt%). However, NiMo/γ-Al2O3 shows higher isomerization activity. The amount of isoparaffins catalyzed by NiMo/γ-Al2O3 and Pd/C were 10.8 and 1.7 wt%, respectively. Physiochemical analysis of the diesel fraction exhibit satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL, while the cetane index was much higher than conventional diesel. © 2016 Elsevier Ltd
Keywords
Waste oil