Optimization and Fuel Property Characterization of Bio-oil from Catalytic Pyrolysis of Achyranthes aspera Wood Residue Using Zeolite Y Catalyst

Abstract

The growing demand for renewable and sustainable energy resources has directed attention towards
biomass pyrolysis as a viable pathway for producing bio-oil, biochar, and syngas. Bio-oil, in particular,
is regarded as a potential substitute for petroleum-based fuels; however, its utilization is limited by
unfavorable properties such as high oxygen content, acidity, volatility, and variable energy values.
These shortcomings affect storage, stability, combustion performance, and compatibility with existing
fuel systems. Although bio-oils from several biomass types have been investigated, limited knowledge
exists on the physicochemical and fuel properties of bio-oil derived from Achyranthes aspera wood
residue, an abundant but underutilized lignocellulosic biomass. Reliable data on properties such as
calorific value, viscosity, density, flash point, pour point, and pH remain scarce. This knowledge gap
restricts proper evaluation of its renewable fuel potential and hinders possible integration into industrial
energy systems. This study analyzed the physicochemical and fuel properties of bio-oil obtained from
catalytic pyrolysis of A. aspera at 400 °C and 500 °C under biomass-to-zeolite Y catalyst ratios of 100/0,
95/5, 90/10, and 85/15. Properties including viscosity, density, flash point, pour point, cloud point, and
pH were determined according to ASTM standards, while higher heating values (HHVs) were estimated
from ultimate analysis correlations. Results showed flash points of 76–82 °C, higher than diesel (75 °C),
suggesting reduced volatility and improved storage safety. Pour points ranged from −4 °C (non-
catalytic) to −3 °C (catalytic), indicating acceptable low-temperature flow behavior. The pH increased
from 7.5 to 8.5 with catalyst loading, demonstrating reduced acidity and lower corrosion risk. Densities
(0.78–0.85 g/ml), viscosities (4.00–4.30 cSt), and API gravities (40.00–45.58) fell within petroleum
fuel ranges, ensuring compatibility with existing infrastructure. HHVs ranged from 29.04–29.07 MJ/kg
(non-catalytic) to 32.07–32.80 MJ/kg (catalytic), reflecting improved energy density and combustion
potential. In conclusion, catalytic pyrolysis significantly enhances the fuel quality of A. aspera bio-oil
by improving stability, acidity, safety, and energy content. These findings position the residue as a
promising renewable feedstock with strong prospects for industrial and energy application