Torrefaction of sorghum biomass to improve fuel properties

Abstract

Torrefaction of energy sorghum and sweet sorghum bagasse was investigated at three different temperatures (250, 275 & 300°C) for 30min to determine product yields and its compositions. The torrefied solid yield ranged from 43% to 65% for sweet sorghum bagasse and 51-70% for energy sorghum. The energy density of both torrefied sorghums increased between 1.6 and 1.4 folds. Besides water, the acetic acid, with a maximum yield of 101.90gL was the dominant compound in the aqueous fraction of liquid products. The aqueous fraction from sweet sorghum bagasse contained furfural and furan carboxyl aldehydes, while ketones and alcohols were dominant from energy sorghum as other key compounds. Phenolic type chemicals and furan derivatives were the major compounds in the oil fraction of the liquid product, accounted up to 58wt%. The condensable liquid products can be further upgraded into high-value platform chemicals.

A Bibliometric Study of Scientific Publications regarding Hemicellulose Valorization during the 2000–2016 Period: Identification of Alternatives and Hot Topics

“…Therefore, after biomass pyrolysis, catalytic conversion of the bio-oil is required so that it can be further processed in an analogous way to conventional oil refineries. One alternative strategy that has been proposed to produce simpler intermediate streams is staged thermal fractionation (also called staged degasification), which can be preceded by biomass torrefaction and the corresponding partial conversion of hemicellulose to compounds such as furfural and furan carboxyl aldehydes or ketones and alcohols [100]. The staged thermal fractionation is guided by the order of thermochemical stability of the biomass constituents, which increases from hemicellulose as the least stable fraction to the most stable cellulose.…”

“…Acid treatments favor hydrolysis of the hemicellulose fraction, whereas alkaline hydrolysis targets the lignin fraction ( Figure 5). Acid hydrolysis processes can be divided in two groups: concentrated acid at low temperature or diluted acid at high temperature [100]. Since the processes based on concentrated acid are quite expensive and may cause operation problems (equipment corrosion), diluted acid processes are more common, with sulfuric acid in the range between 0.5% and 2.5% being the most representative case [118].…”

Energy valorization of woody biomass by torrefaction treatment: A Brazilian experimental study

“…Partial degradation of the biomass fibrous structure enhances the grindability of this material and reduces the availability of hydrophilic groups for the adsorption of water, making it less hygroscopic (Van der Stelt et al 2011, Esteves and Pereira, 2009, Medic et al 2012. Figure 1: Changes on the physical and chemical properties of lignocellulosic biomass subjected to dry torrefaction for energy purposes (Du et al 2014, Acharya et al 2015, Pérez et al 2015, Bach and Skreiberg 2016, Yue et al 2017.…”

Review of Biofuel Technologies in WtL and WtE

“…Among researchers, torrefaction has been viewed as an excellent pretreatment for improving the energy recovery features of several wastes creating products with low oxygen to carbon ratios and high calorific values for co-gasification and cocombustion applications [50]. As an example, the torrefaction of several pomaces [51] and prunings [52] led to very promising results with calorific values increased to near lignite levels. Other interesting results have been reported by researchers [50] dealing with the very heterogeneous nature of MSW which along with high moisture contents make them challenging for application in WTE and WTL processes.…”