Production of Phenol-Rich Bio-Oil from Tea Waste via Catalytic Pyrolysis Using Fe-Modified Activated Carbon

Abstract

This study investigates the catalytic pyrolysis of tea waste—an abundant lignin-rich biomass—using Fe-modified activated carbon (Fe-AC) as a catalyst to enhance the yield of phenol-rich bio-oil. The pyrolysis process, conducted at varying temperatures (400-600°C), demonstrates a marked increase in bio-oil yield and phenolic content when compared to non-catalytic pyrolysis. The catalytic approach results in a 13% improvement in bio-oil yield at 500°C, reaching 48.9%, and a significant shift in the bio-oil composition towards phenolic compounds, which rose by 46.7%, while reducing the levels of undesirable by-products such as acids and aldehydes Thermogravimetric analysis (TGA) and kinetic modeling using the Distributed Activation Energy Model (DAEM) reveal that the Fe-AC catalyst significantly lowers the activation energy of the pyrolysis process, facilitating more efficient decomposition and a greater selectivity for phenolic compounds. GC-MS and TG-FTIR analyses further confirm the enhanced quality and stability of the bio-oil, highlighting its potential for use as a renewable energy source and as a feedstock to produce value-added chemicals. This study underscores the viability of using Fe-modified activated carbon as a cost-effective and scalable catalyst for improving the efficiency and sustainability of bio-oil production from tea waste, contributing to the broader objectives of waste valorization and circular economy initiatives.