Torrefaction interpretation through morphological and chemical transformations of agro-waste to porous carbon-based biofuel

Abstract

In the current study, two agro-waste lignocellulosic corncob (CC) and rice husk (RH) were thermally torrefied at 200–300 °C into a porous carbon-enriched biofuel. The scanning electron microscopy (SEM) of produced biofuel confirmed the rounded, homogenous, and spherical structure of the produced biofuels with higher porosity at a temperature between 250 and 300 °C with 60 min retention time. Brunauer-Emmett-Teller (BET) analysis indicated the high surface area (CC: 1.19–2.87 m2 g−1 and RH: 1.22–2.67 m2 g−1) and pore volume (CC: 1.23–2.81 ×10−3 m3 g−1 and RH: 1.46–2.58 ×10−3 m3 g−1). Crystallinity index decline percent (CC= 62.87% and RH=57.10%) estimated thermal stability and rise in amorphous cellulose reformation during (250–300 °C)/60 min that would efficiently hydrolyze during oxidative pyrolysis carbon reactive sites the rise in surface area and total pore’s volume, having higher conversion rate as compared to raw materials. Carbon content was upgraded to 94% by eliminating hydrogen and oxygen from lignocellulosic agro-waste to produce energy-dense CC and RH. The lignin macromolecule transformation extent was estimated by O/C trend, which was equal to 63% and 47% for CC and RH, respectively, at 300 °C for 60 min. Due to low bulk density and pre-grinding energy requirements, torrefied biofuel with decomposed fibrous structure have lower transportation costs.

Keywords

• Torrefaction
• Agro-waste
• Aromaticity
• Lignin demethoxylation
• O/C ratio