Waste Coal Utilization in India: A Review

Pyrolysis Kinetics of Byrsonima crassifolia Stone as Agro-Industrial Waste through Isoconversional Models

“…The experimental TGA and calculated DTG curves obtained for the Nanche endocarp under a heating rate of 5 • C/min and variable particle size are presented in Figure 1. Here it can be observed that the devolatilization zone occurs from 250 • C to 450 • C. Furthermore, a decrease in particle size Dp < 600 µm causes a higher devolatilization of the biomass ~79.050%, i.e., a higher amount of volatile material is generated and thus a lower amount of biochar (Figure 1) [28]. From the DTG curves (Figure 1), it can be observed changes in hemicellulose degradation (shoulder at ~275 • C).…”

“…Yang et al [31] report the temperature ranges for the degradation of hemicellulose, cellulose, and lignin as 220-315, 315-400, and 160-900 • C, respectively, and more specifically, it has been found that cellulose degrades between 277 and 427 • C, hemicellulose around 197 and 327 • C and lignin between 277 and 527 • C [32]. Furthermore, it is observed that when the heating rate is high, the degradation rate becomes slower due to the restriction of heat transfer between the particles, as opposed to a slow heating rate where the heat remains in the biomass for a longer time, thus resulting in an intense heat transfer between the particles favoring a higher degradation rate, allowing a greater amount of dehydration, depolymerization, carbonylation, carboxylation, and transglycosylation reactions [28], thus causing a decrease in the DTG max value (%/ • C) presented in Table 2. Concerning the fact that a reverse behavior is observed in the temperature range of 315-400 • C with respect to the hemicellulose decomposition, this can be explained by the behavior of the cellulose decomposition reported by Várhegyi et al [33], where mass transfer problems caused by high heating rates can delay the decomposition process, and in the case of cellulose the presence of reaction products during its decomposition can initiate autocatalytic reactions and cellulose can be consumed below the maximum cellulose decomposition temperatures, thus causing a shift and decrease in the maximum peak cellulose degradation of DTG's as in the present study.…”