Abstract
We evaluated the thermogravimetric and devolatilization rates of hemicellulose and cellulose, and the calorimetric behavior of the torrefied biomass, of five tropical woody species (Cupressus lusitanica, Dipteryx panamensis, Gmelina arborea, Tectona grandis and Vochysia ferruginea), at three temperatures (TT) and three torrefaction times (tT) using a thermogravimetric analyzer. Through a multivariate analysis of principal components (MAPC), the most appropriate torrefaction conditions for the different types of woody biomass were identified. The thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) analysis showed that a higher percentage of the hemicellulose component of the biomass degrades, followed by cellulose, so that the hemicellulose energy of activation (Ea) was less than that of cellulose. With an increase in TT and tT, the Ea for hemicellulose decreased but increased for cellulose. The calorimetric analyses showed that hemicellulose is the least stable component in the torrefied biomass under severe torrefaction conditions, and cellulose is more thermally stable in torrefied biomass. From the MAPC results, the best torrefaction conditions for calorimetric analyses were at 200 and 225 °C after 8, 10, and 12 min, for light and middle torrefaction, respectively, for the five woody species.
Highlights
Biomass is widely available worldwide, and often used in biofuel production to help reduce the use of fossil energy reserves and mitigate problems the environmental problems caused by petroleum derived fuels [1]
The present study aimed to evaluate the thermogravimetric behaviour, devolatilization of hemicellulose and cellulose, and the calorimetric behaviour of the torrefied biomass of five tropical woody species (Cupressus lusitanica, Dipteryx panamensis, Gmelina arborea, Tectona grandis and Vochysia ferruginea), at three temperature conditions and three torrefaction times using simultaneous thermogravimetric and differential scanning calorimetry analyses
The thermogravimetric decomposition behavior of the torrefied biomass for the five species showed the same pattern with different TT and torrefaction times (tT) (Figure 3a–h)
Summary
Biomass is widely available worldwide, and often used in biofuel production to help reduce the use of fossil energy reserves and mitigate problems the environmental problems caused by petroleum derived fuels [1]. Despite the importance of biomass, it has not been developed into other types of energy, such as hydroelectricity, eolic, or solar energies, which are being highly exploited [3]. Despite the increase in the use of biomass as an energy source, some disadvantages still limit its optimum performance, such as difficulties in collection due to disperse distribution, irregular shape, high volume, low energy density, and storage and transportation problems [2]. These problems affect the variability of the biomass’s physical properties [4]. Other challenges posed by biomass include its Energies 2018, 11, 696; doi:10.3390/en11040696 www.mdpi.com/journal/energies
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