Seasonal Harvesting Impact on Biomass Fuel Properties and Pyrolysis-Derived Bio-Oil Organic Phase Composition

Thermochemical conversion of giant reed biomass during periodic variations has been carried out in a semi-batch tubular reactor at 550°C. This study was carried out after the incineration of giant reed along the river banks. Four periodic variations, late spring (HS-4), late summer (HS-1), late autumn (HS-2), and late winter (HS-3) were considered to investigate the effect of harvest time on biomass fuel properties, pyrolysis product distribution, non-condensable gas characterization, and bio-oil organic phase (BOP) fuel properties. The considered biomasses herein had average calorific values of 18.86 ± 0.05, 19.73 ± 0.05, 19.23 ± 0.04, and 18.44 ± 0.04 MJ/kg during HS-1, HS-2, HS-3, and HS-4, respectively. The biomass, bio-oil organic phase, biochar, and pyrolysis gas were characterized using thermogravimetric analysis (TGA), gas chromatography–mass spectroscopy (GCMS), Fourier transform infrared spectroscopy (FTIR), micro-GC, and scanning electron microscopy (SEM/EDS). The organic phase of bio-oil was isolated using a 125 mL separating funnel, allowing natural stratification of the immiscible phases. BOP yield increased from 5 to 11 wt% during HS-4 and HS-3, respectively. Higher heating values (HHV) of the BOP ranged from 19.4 ± 0.03 to 22.6 ± 0.02 MJ/kg in relation to the active growth stage and senescence-dormant phase. Physical and chemical properties (TAN, density, viscosity, water content, and CHNS) and chemical compound groups of organic phase bio-oil were analyzed. The produced BOP was rich in phenolics for all considered periods. The effect of harvest time showed that biomass and bio-oil organic phase fuel properties are improved during the senescence-dormant period. As a result, giant reed biomass should be harvested during autumn to avoid incineration that releases carbon dioxide into the atmosphere and will also reduce the occurrence of artificial flooding.