Sweet sorghum bagasse pyrolysis: Unravelling thermal degradation via slow and flash pyrolysis investigations

Abstract

This study examines the intricate thermal decomposition of sweet sorghum bagasse, an agricultural residue with significant potential as a renewable energy and biofuel feedstock. Both slow and flash pyrolysis has been conducted over a temperature range of 300–450°C and flash pyrolysis experiments were performed through analytical pyrolysis via Py-GC/MS to comprehensively assess the pyrolysis behaviour and elucidate the biomass degradation pathways. In the slow pyrolysis experiments, sweet sorghum bagasse underwent controlled thermal decomposition at different temperatures (300–450°C), allowing for the investigation of the influence of temperature on product yields and compositions. The evolved volatile compounds and biochar products were analyzed to determine the impact of temperature on biomass degradation. The results revealed that 400°C is the optimum pyrolysis temperature for maximizing valuable bio-oil production with approximately 42 wt.% yields with an overall conversion of 73%. Various characterization techniques were employed to analyze the slow pyrolysis products, including GC-MS, TGA, FTIR, SEM, and XRD. Flash pyrolysis was employed to provide a detailed understanding of the rapid biomass breakdown under extreme heating conditions with a heating rate of 20°C/ms to complement the slow pyrolysis findings. This technique elucidated the primary mechanisms responsible for the degradation of sweet sorghum bagasse, shedding light on the fragmentation patterns and the formation of vital intermediate compounds during flash pyrolysis. These insights into the transient phenomena occurring during pyrolysis provide valuable information for developing efficient and sustainable biomass conversion processes.

Graphical abstract

The pyrolysis behaviour of sweet sorghum bagasse (SSB) is comprehensively assessed using TGA, slow pyrolysis via lab scale glass tubular reactor and flash pyrolysis via analytical tool Py-GC/MS from 300–450°C. The study reveals the potential use of SSB as a renewable energy and biofuel feedstock.