Pyrolysis of Napier grass in a fixed bed reactor:effect of operating conditions on product yields and characteristic

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Mohammed, Isah Yakub ; Abakr, Yousif Abdalla ; Kazi, Feroz Kabir ; Yusuf, Suzana ; Alshareef, Ibraheem ; Chin, Soh Aik (2015)
  • Publisher: Dept. of Wood and Paper Science, College of Natural Resources, North Carolina State University
  • Journal: BioResources (issn: 1930-2126, eissn: 1930-2126)
  • Related identifiers: doi: 10.15376/biores.10.4.6457-6478
  • Subject: Biotechnology | Pyrolysis | Napier grass | Non-condensable | Bio-oil | Characterization | Bio-char | TP248.13-248.65

This study presents a report on pyrolysis of Napier grass stem in a fixed bed reactor. The effects of nitrogen flow (20 to 60 mL/min), and reaction temperature (450 to 650 degrees C) were investigated. Increasing the nitrogen flow from 20 to 30 mL/min increased the bio-oil yield and decreased both bio-char and non-condensable gas. 30 mL/min nitrogen flow resulted in optimum bio-oil yield and was used in the subsequent experiments. Reaction temperatures between 450 and 600 degrees C increased the bio-oil yield, with maximum yield of 32.26 wt% at 600 degrees C and a decrease in the corresponding bio-char and non-condensable gas. At 650 degrees C, reductions in the bio-oil and bio-char yields were recorded while the non-condensable gas increased. Water content of the bio-oil decreased with increasing reaction temperature, while density and viscosity increased. The observed pH and higher heating values were between 2.43 to 2.97, and 25.25 to 28.88 MJ/kg, respectively. GC-MS analysis revealed that the oil was made up of highly oxygenated compounds and requires upgrading. The bio-char and non-condensable gas were characterized, and the effect of reaction temperature on the properties was evaluated. Napier grass represents a good source of renewable energy when all pyrolysis products are efficiently utilized.
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