Critical evaluation of global mechanisms of wood devolatilization

Branca, Carmen; Albano, Alessandro; Blasi, Colomba Di

doi:10.1016/j.tca.2005.02.030

Cited by 190 publications

(119 citation statements)

References 22 publications

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“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Its variance is small ( E,1 =1.8 kJ/mol), which is in accord with the earlier observations on the first order kinetics of cellulose decomposition. The mean of the activation energy distribution, 167 kJ/mol is lower than the usual activation energy values.…”

Section: 3supporting

confidence: 91%

“…4 Therefore the TGA experiments of biomass materials are evaluated nowadays by the non-linear method of least squares (LSQ), assuming more then one reaction. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Biomass samples usually contain many different pyrolyzing species. Even the same chemical species may have differing reactivity if their pyrolysis is influenced by other species in their vicinity.…”

Section: Introductionmentioning

confidence: 99%

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Thermal Decomposition of Wheat, Oat, Barley, and Brassica carinata Straws. A Kinetic Study

2009

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ABSTRACT. The slow pyrolysis of four biomass samples was studied by thermogravimetry (TGA) at different heating rates. The samples belonged to different botanical classes/genera and their mineral matter content showed a high variation. A distributed activation energy model (DAEM) was used due to the complexity of the biomass samples of agricultural origin. The common features of their decomposition kinetics were sought by evaluating 12 experiments of four biomasses simultaneously by the method of least squares. Two parallel DAEM reactions with a Gaussian distribution of the activation energies were sufficient for an acceptable fit between the experimental and simulated data.Common means and deviations of the activation energies were required for all the four samples. The reactivity differences between the samples were expressed by the differences between the preexponential factors while the weights of the parallel reactions described further differences between the samples. Altogether 20 unknown model parameters were estimated from 12 experiments. When the method of 2 least squares was used on the mass loss rate (DTG) curves, one of the obtained partial curves showed a sharp peak with a small variation of E. This was associated with the cellulose decomposition. The other partial curve had a much wider E distribution and was assumed to include the decomposition of hemicellulose, lignin and extractives. The evaluation of the sample mass (TGA) data resulted in wider partial peaks than the ones obtained from the DTG data. To exclude the possibility of any mathematical artifact, the evaluation was also carried out on the analytical integrals of the DTG curves.

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Section: 3supporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Thermal Decomposition of Wheat, Oat, Barley, and Brassica carinata Straws. A Kinetic Study

2009

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“…The E0,2 values were found to be 185 -186 kJ/mol, which is safely in the range of the activation energies reported for the cellulose components of biomass materials. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] On the other hand, the E0,1 and E0,3 values of Table 3 are considerably higher than the reported activation energies for the decomposition of hemicelluloses and lignin in studies based on first order or nth order kinetics. 8 One can consider here that the activation is nearly inversely proportional to the width of the DTG curves in the first order and nth order models at linear T(t).…”

Section: Notes On the Pseudocomponents And On The Magnitudes Of The Omentioning

confidence: 57%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The biomass fuels and raw materials contain a wide variety of pyrolyzing species. Even the same chemical species may have different reactivity if their pyrolysis is influenced by other species in their vicinity.…”

Section: Introductionmentioning

confidence: 99%

Thermogravimetric Study of Biomass Pyrolysis Kinetics. A Distributed Activation Energy Model with Prediction Tests

et al. 2010

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ABSTRACT. The pyrolysis of four biomasses (corn stalk, rice husk, sorghum straw and wheat straw) was studied at different temperature -time functions in inert gas flow by thermogravimetric analysis (TGA). Linear and stepwise heating programs were employed. A distributed activation energy model (DAEM) with three pools of reactant (three pseudocomponents) was used due to the complexity of the biomass samples of agricultural origin. Compensation effects were observed between the kinetic parameters similarly to the works of other investigators. The compensation effects result in ambiguous parameter values hence they were eliminated by decreasing the number of the unknown parameters. For this purpose part of the kinetic parameters was assumed to be the same for the four biomasses. This approach also helps to express the similarities of the samples in the model. The sixteen experiments were evaluated simultaneously by the method of least squares to obtain dependable kinetic parameters. 2The resulting models described well the experimental data and were suitable for predicting experiments at higher heating rates. The checks on the prediction capabilities were considered to be an essential part of the model verification.

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“…The proportions of these constituents and the presence the ions inorganic can vary the decomposition characteristics from one species to another, even within the same species [2,24,25]. Another influencing factor is the heating rate at which the experiments are carried out [26]. Despite the numerous weight loss measurements available in the literature, a systematic classification of biomass fuels, based on thermogravimetric analysis, and general mechanisms to interpret such measurements are not available.…”

Section: Introductionmentioning

confidence: 99%

Corn stover thermal decomposition in pyrolytic and oxidant atmosphere

Conesa¹,

Urueña²,

Dı́ez³

2014

Journal of Analytical and Applied Pyrolysis

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The pyrolysis and combustion of corn stover were studied by dynamic thermogravimetry and derivate thermogravimetry (TG-DTG) at heating rates of 5, 10, 20 and 50 K min -1 at atmospheric pressure. For the simulation of pyrolysis and combustion processes a kinetic model based on the distribution of activation energies was used, with three pools of reactants (three pseudocomponents) because of the complexity of the biomass samples of agricultural origin. The experimental thermogravimetric data of pyrolysis and combustion processes were simultaneously fitted to determine a single set of kinetic parameters able to describe both processes at the different heating rates. The model proposed achieves a good correlation between the experimental and calculated curves, with an error of less than 4 % for fitting four heating rates simultaneously. The experimental results and kinetic parameters may provide useful data for the design of thermo decomposition processing system using corn stover as feedstock. On the other hand, analysis of the main compounds in the evolved gas is given by means of a microcromatograph.

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Critical evaluation of global mechanisms of wood devolatilization

Cited by 190 publications

References 22 publications

Thermal Decomposition of Wheat, Oat, Barley, and Brassica carinata Straws. A Kinetic Study

Thermal Decomposition of Wheat, Oat, Barley, and Brassica carinata Straws. A Kinetic Study

Thermogravimetric Study of Biomass Pyrolysis Kinetics. A Distributed Activation Energy Model with Prediction Tests

Corn stover thermal decomposition in pyrolytic and oxidant atmosphere

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