Thermogravimetric analyses and kinetic modeling of pellets built with three Cameroonian biomass

Vitoussia, Théophile; Brillard, Alain; Kehrli, Damaris; Kémajou, Alexis; Njeugna, Ebénézer; Brilhac, Jean-François

doi:10.1007/s13399-019-00558-3

Cited by 7 publications

(6 citation statements)

References 18 publications

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“…Activation energy values, obtained for the conversion of the biochar samples in an inert medium, were varied in range 10-35 kJ/mol, which were much smaller than usually reported values for the decomposition of main components of the nut shells-100-350 kJ/mol [9,[37][38][39][40]. Close values were reported in [3,8] for lignin fiber decomposition in ranges 38-42 and 19-45 kJ/mol, respectively. Thus the mass loss observed during TG experiments in inert medium could be caused by slow lignin fiber decomposition.…”

Section: Kinetic Analysis Of the Biochar Thermal Conversionmentioning

confidence: 77%

“…Biochar obtained could be used as a feedstock for production of supercapacitors, batteries, and as fuel, catalyst, or adsorbent [1]. Nut shells are a widespread biomass in many regions worldwide [3], which makes them a suitable feedstock for this process. The biochar, obtained via pyrolysis of nut shells, is known to be a suitable carbon-neutral fuel [3] and a feedstock for many other applications.…”

Section: Introductionmentioning

confidence: 99%

“…Nut shells are a widespread biomass in many regions worldwide [3], which makes them a suitable feedstock for this process. The biochar, obtained via pyrolysis of nut shells, is known to be a suitable carbon-neutral fuel [3] and a feedstock for many other applications. A common issue, in this area, is varying properties of different biomass feedstocks, making obtaining products with stable characteristics problematic.…”

Section: Introductionmentioning

confidence: 99%

“…Kinetic data on the pyrolysis of shells of different nuts is widely presented in literature [3,[8][9][10]. However, these data significantly vary depending on type of the feedstock and the experimental method used.…”

Section: Introductionmentioning

confidence: 99%

“…The sensitivity analysis [11] revealed that the variation in activation energy has the most significant effect on the pyrolysis rate making such uncertainty critical for practical calculations. In [3], it was reported that the kinetics of thermal degradation and oxidation of biochar pellets, consisting of coffee husk, palm nut shells, and fibers could be determined according to the superposition principal using kinetic parameters of individual components. Thus, the experiment appears to be the most reliable method to study the pyrolysis of nut shells.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the Physicochemical Characteristics of Biochar Obtained by Slow Pyrolysis of Nut Shells in a Nitrogen Atmosphere

et al. 2021

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The process of slow pyrolysis of seven nut shell samples, in a nitrogen-purged atmosphere, has been studied, as well as characteristics of biochar obtained. The heat carrier with a temperature of 400–600 °C (with a step of 100 °C) was supplied indirectly using a double-walled reactor. The heating rate was 60 °C/min. At increased temperature of the heating medium, a decrease in the amount of the resulting carbon residue averaged 6.2 wt%. The release of non-condensable combustible gas-phase compounds CO, CH4, and H2, with maximum concentrations of 12.7, 14.0, and 0.7 vol%, respectively, was registered. The features of the obtained biochar sample conversions were studied using thermal analysis in inert (nitrogen) and oxidative (air) mediums at 10 °C/min heating rate. Kinetic analysis was performed using Coats–Redfern method. Thermal analysis showed that the main weight loss (Δm = 32.8–43.0 wt%) occurs at temperatures ranging between 290 °C and 400 °C, which is due to cellulose decomposition. The maximum carbon content and, hence, heat value were obtained for biochars made from macadamia nut and walnut shells. An increased degree of coalification of the biochar samples affected their reactivity and, in particular, caused an increase in the initial temperature of intense oxidation (on average, by 73 °C). While technical and elemental composition of nut shell samples studied were quite similar, the morphology of obtained biochar was different. The morphology of particles was also observed to change as the heating medium temperature increased, which was expressed in the increased inhomogeneity of particle surface. The activation energy values, for biochar conversion in an inert medium, were found to vary in the range of 10–35 kJ/mol and, in an oxidative medium—50–80 kJ/mol. According to literature data, these values were characteristic for lignin fibers decomposition and oxidation, respectively.

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