Biochar from oil palm empty fruit bunches and oil palm shells via slow pyrolysis
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Date
2014-08
Authors
Mohamad Aziz, Nur Syairah
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Abstract
The objectives of this study are to produce biochar from oil palm empty fruit bunches (EFB) and oil palm shell (OPS) via laboratory-scale slow pyrolysis system, investigate the characteristics of biochar produced from various feedstock and pyrolysis conditions, and compare the biochar produced from EFB and OPS. The preliminary analysis was performed on both feedstocks to investigate their properties. The water washing pre-treatment was carried out on the EFB feedstock to vary the ash content of the feedstock. For the EFB feedstock, the impacts of holding time and feedstock ash content on the biochar yield and characteristics were investigated. The holding time was varied from 0.5 h to 4.0 h, while the terminal temperature and heating rate were fixed at 550 °C and 5 °C/min respectively. The EFB feedstock in the range of 1.60 to 5.29 mf wt % of ash content were pyrolyzed at 550 °C and 5 °C/min heating rate for 1 h holding time. For the OPS feedstock, the impacts of terminal temperature and holding time on the biochar yield and characteristics were studied. The OPS were pyrolyzed at 6 different terminal temperature; 400 °C, 450 °C, 500 °C, 550 °C, 600 °C and 650 °C at 5 °C/min heating rate for 1 h holding time. The holding time was then varied from 0.5 h to 4.0 h, while the terminal temperature and heating rate were fixed at 550 °C and 5 °C/min respectively. The biochar, liquid and gas yields were determined. The biochar was analyzed via proximate and elemental analysis, surface morphology study and BET surface area analysis. It was observed that the holding time had little influence on the product yields for both EFB and OPS feedstock. It was found that 1.0 h and 4.0 h are the optimum holding time for EFB and OPS biochar production respectively. As the terminal temperature elevated, the OPS biochar yield reduced while the fixed carbon content and BET surface area increased. The reduction of ash content in the EFB feedstock via water washing pre-treatment led to a decrease of biochar yield and corresponding increase of biochar‟s
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fixed carbon content and BET surface area. The slow pyrolysis of OPS feedstock produced higher biochar yield as compared to EFB feedstock for varied holding times between 0.5 h to 4.0 h. The analysis of biochar characteristics found that the OPS biochar contain higher fixed carbon content and has larger BET surface area as compared to the EFB biochar. This study shows that OPS biochar produced from the laboratory-scale slow pyrolysis process has better quality as compared to the EFB biochar.
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Keywords
Oil Palm , Pyrolysis