Pyrolysis of low-value waste sawdust over low-cost catalysts: physicochemical characterization of pyrolytic oil and value-added biochar

Abstract

The present work deals with an experimental investigation into the generation and characterization of pyrolytic oil and biochar from Sal wood sawdust (SW). The pyrolysis experiment was performed in a semi-batch reactor at 500 oC and 80 oC/min heating rate with CaO, CuO, and Al2O3 catalysts. Further, the pyrolytic oil and biochar were investigated using different analyses, including proximate analysis, elemental analysis, thermal stability, GC-MS, FTIR, field emission scanning electron microscopy, electrical conductivity analysis, higher heating value (HHV), zeta potential analysis, and ash content analysis. Pyrolysis results revealed that compared to thermal pyrolysis (46.02 wt%), the pyrolytic oil yield was improved by catalytic pyrolysis with CaO and CuO (50.02 and 48.23 wt%, respectively). Further, the characterization of pyrolytic oil revealed that the loading of catalysts considerably improved the oil's properties by lowering its viscosity (69.50 to 22 cSt), ash content (0.26 to 0.11 wt%), and oxygen content (28.32 to16.60 %) while raising its acidity (4.2 to 9.6), heating value (25.66 to 36.09 MJ/kg), and carbon content (61.79 to 74.28%). According to the FTIR analysis, the pyrolytic oil contained hydrocarbons, phenols, aromatics, alcohols, and oxygenated compounds. Additionally, the GC-MS analysis showed that catalysts significantly reduced oxygenated fractions, phenols (20.23 to 15.26%), acids (12.23 to 6.56%), and increased hydrocarbons (12 to 16 wt%). Additionally, the results of the biochar analysis demonstrated that SW biochar was appropriate for a range of industrial applications, including in catalysts, supercapacitors, fuel cells, and bio-composite materials.