Influence of Zeolite Y Loading on Product Distribution and GC-MS Characterization of Bio-oil from Achyranthes aspera Wood Residue Pyrolysis

Abstract

Biomass-derived bio-oil represents a promising renewable alternative to fossil fuels; however, its high
oxygen content, chemical instability, and acidity severely limit direct utilization. Conventional
pyrolysis of lignocellulosic residues yields bio-oils containing numerous oxygenated compounds
including phenols, carboxylic acids, ketones, and furans that contribute to corrosivity and low heating
value. Catalytic upgrading strategies are therefore essential to enhance bio-oil stability and commercial
viability. Achyranthes aspera wood residue, an abundant yet underutilized lignocellulosic biomass in
Nigeria and similar regions, remains unexplored as a pyrolysis feedstock despite its favorable
phytochemical composition. This study presents the first systematic investigation of the catalytic
pyrolysis of A. aspera wood residue using zeolite Y catalyst to improve bio-oil quality at the molecular
level. Pyrolysis experiments were conducted at 500°C under a nitrogen atmosphere using biomass-to-
catalyst ratios of 100/0, 95/5, 90/10, and 85/15 (wt.%). Product yield analysis showed that bio-oil
production decreased from 52.95 wt.% (95/5 ratio) to 29.45 wt.% (85/15 ratio) with increasing catalyst
loading, while syngas yield increased proportionally from 22.40 wt.% to 53.50 wt.%. Gas
Chromatography–Mass Spectrometry (GC-MS) revealed significant compositional improvements:
phenolic compounds increased from 19.95% (non-catalytic) to 33.08% (85/15 ratio), representing a
65.8% enhancement, while carboxylic acids decreased from 5.28% to 4.19%, a 20.64% reduction.
Statistical analysis (ANOVA, p < 0.05) confirmed that catalyst loading significantly influenced both
product distribution and molecular composition. The catalytic upgrading promoted deoxygenation,
demethoxylation, and aromatic enrichment pathways, yielding phenol-rich bio-oil with enhanced
stability and reduced acidity. Optimal catalyst loading of 5–10 wt.% provided a balance between bio-
oil yield and quality improvement. These findings establish A. aspera residue as a viable feedstock for
producing value-added bio-oils applicable in renewable fuels, resins, pharmaceuticals, and specialty
chemicals, while demonstrating zeolite Y's effectiveness in tailoring bio-oil composition for industrial
applications.