Thermogravimetric study on the pyrolysis kinetics of apple pomace as ...

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Thermogravimetric study on the pyrolysis kinetics of apple pomace as waste biomass M. R. Baray Guerrero a, M. Marques da Silva Paula b, n Velderrain a, M. Melendez Zaragoza a, J. Salinas Gutierrez a, V. Guzma pez Ortiz a, V. Collins-Martıńez a,* A. Lo Departamento de Materiales Nanoestructurados, Centro de Investigacion en Materiales Avanzados, S.C., Miguel de Cervantes 120, Chihuahua, Chih. 31109, Mexico b Laboratory of Synthesis of Multifunctional Complexes, PPGCS, Universidade do Extremo Sul Catarinense, 88806-000 Criciu´ma, SC, Brazil a

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Biomass waste-to-energy is an attractive alternative to fossil feedstocks because of

Available online 23 July 2014

essentially zero net CO2 impact. A viable option consists in an integrated process, in which biomass is partly used to produce valuable chemicals with residual fractions employed for

Keywords:

hydrogen production. One example of a biomass waste is the apple pomace, which is the

Apple pomace

residue generated in the process of extraction of apple juice. In this research, a kinetic

Waste pyrolysis

study of the pyrolysis of apple pomace biomass (APB) was performed by TGA aiming its

TGA

liquid and gaseous products be utilized for the production of valuable chemicals and

Kinetics

hydrogen. Characterization of APB consisted in calorific value, compositional, proximal and elemental analyzes. Kinetics were evaluated using three iso-conversional TGA models at 5, 10, 15 and 20 C/min. Activation energy values of 213.0 and 201.7 kJ/mol were within the range for hemicellulose and cellulose, respectively, which are the main components of biomass. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Introduction The current global economic development is based on the trade and processing of oil, however, depletion is expected during the first quarter of this century, which poses both economic and energy supply problems because energy demand is met mainly from fossil fuels [1]. Biomass as a renewable source not only allows to partially replace fossil fuels, but also to reduce concentrations of gaseous pollutants

(carbon oxides) emitted into the atmosphere [2]. Agroindustrial residues represent a renewable source of energy, as obtained in large quantities as a result of industrial processing of fruits and vegetables and are a cheap raw material for conversion to biofuels [3]. Moreover the use of renewable energy technologies such as wind, geothermal, hydro, solar, hydrogen and those obtained from biomass are alternatives in the medium and long-term for the replacement of fossil fuels [4]. Today hydrogen is generated mostly from fossil fuels with a consequent, release of CO2

* Corresponding author. Tel.: þ52 6144391129. E-mail address: [email protected] (V. Collins-Martıńez). http://dx.doi.org/10.1016/j.ijhydene.2014.06.012 0360-3199/Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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during its production stage. While, biomass waste-to-energy is an attractive alternative to fossil feedstocks because of essentially zero net CO2 impact. A viable economical option consists in an integrated process, in which biomass is partly used to produce valuable materials or chemicals with residual fractions employed for hydrogen production. Therefore, the transformation of waste biomass into energy valued compounds (i. e. H2) is a research field that is considered of great importance in the present due to the current energy crisis and environmental pollution issues [2]. Furthermore, biofuels produced from various lignocellulosic materials such as wood, agricultural or forest residues, have the potential to be a valuable substitute (or supplement to gasoline biofuels) to liquid or gaseous fuels for the transport sector [4]. One specific example of a biomass waste is the apple pomace, which is the residue generated in the process of extraction of apple juice. This apple pomace, is formed by a complex mixture of shell, seed kernel, calyx, stem and soft tissue, which is representative of the pomace, and this contains mainly cellulose, hemicellulose, lignin and pectin. The processing of biomass is grouped into three major groups: biochemical, thermochemical and physicochemical. Basically three types of thermochemical processes are distinguished: pyrolysis, gasification and combustion. The term pyrolysis refers to the incomplete thermal degradation which leads to the production of coal tars and condensable liquids and gases. In its strictest sense, pyrolysis must be performed in complete absence of oxygen, however, this term is now used in a broader connotation, to describe the chemical changes caused by the action of heat [5]. Moreover, pyrolysis is typically studied based on hypothetical models [6], where it is considered that the overall performance of pyrolysis is the combination of the behavior of each individual component [6,7]. Therefore, the determination of the kinetic parameters provides key information of the processes that take place, as well as the structure and composition of its constituents [6]. Furthermore, the analysis of the thermal degradation volatile products, identifies the gaseous species emitted by the biomass, and thus provides insights to the processes through which such decomposition occurs. The determination of the decomposition kinetics of lignocellulosic biomass involves the knowledge of the reaction mechanisms. However, the number of reactions occurring simultaneously in the simplest pyrolysis process is so great that prevents to develop a kinetic model that takes into account all these reactions. A kinetic study aims to reveal how the thermal decomposition takes place (whether one or more processes and what range of conversions occur) through the characteristic kinetic constants provided by the kinetic models. This last is critical to the design, construction and operation on a large-scale reactor for the pyrolysis of apple pomace subject to study, for the use of valued chemicals that may be generated or for the production of hydrogen from gaseous products or simply to get rid of certain wastes in a clean way [6]. The kinetic analysis of the thermal decomposition of biomass is generally based on the rate equation of decomposition of solids [8]. The present research is aimed to perform a basic characterization of apple pomace (from the region of Cuauhtemoc, Chihuahua, Mexico), the determination of the kinetic parameters (activation energy and pre-exponential factor) of the

pyrolysis reaction under a nitrogen atmosphere using differential and integral non-isothermal iso-conversional models. Furthermore, the models employed in the present research were: the differential Friedman and two integral FlynneWalleOzawa (FWO) and KissingereAkahiraeSunose (KAS) models on TGA data for the apple pomace biomass (APB).

Experimental Sample characterization Apple pomace samples were collected from the northern state moc, Chihuahua) and subjected to a of Chihuahua (Cuauhte drying process, crushed, grounded and sieved to achieve a particle size of 150 mm. The elemental and proximal analyzes for the apple pomace sample were performed using a Carlo Erba EA-1110 elemental analyzer and an atomic emission spectrometer coupled with ICP (ICP Thermo Jarrell Ash IRIS/AP DUO), calorific power was determined through an adiabatic bomb calorimeter (Parr-1341 Oxygen Bomb Calorimeter) following the standard test method ASTM D-2015-96. Lignin, cellulose, hemicellulose and pectin content from the pomace were determined using gravimetric techniques, described in ASTM (E 1756-95, D1106-95) and ASTM (D1103-60). Moisture, volatiles and ash content was determined according to the procedure described in ASTM E (871-82), ASTM (872-82) and ASTM (1755e1795), respectively. In order to determine the particle size (dp), samples were analyzed with dimensions: dp < 150 mm (150 mm), 150 < dp < 180 mm (180 mm), 180 < dp < 250 mm (250 mm), and 250 < dp < 450 mm (450 mm) under 100 cm3/min N2 flow and heating from room temperature to 800 C at a rate of 10 C/min. To verify the effect of the heating rate on the generation of volatiles and to obtain the kinetic parameters, the pomace sample was used with the same particle size, which was subjected to different heating rates of 5, 10, 15 and 20 C/min.

Thermogravimetric analysis TGA tests were carried out under an inert atmosphere (N2) using a TGA-Q-500, TA Instruments equipment. Heating rates (b) were controlled at 5, 10, 15 and 20 C/min. Experiments were performed under a nitrogen atmosphere with a flowrate of 100 cm3/min and by duplicate. In all TGA tests between 20 and 30 mg of apple pomace biomass (APB) sample with a specific particle size were deposited on the crucible of the thermo balance. Then this sample was the subjected to a specific heating rate from room temperature to 800 C.

Kinetic models During the pyrolysis primary reactions occur, so that the kinetic study of these are of paramount importance with TGA being a very powerful tool. The determination of decomposition kinetics of lignocellulosic materials involves the knowledge of the reaction mechanisms. However, the number of reactions occurring simultaneously during a simple pyrolysis process is so great that prevents the development of a kinetic


model that takes into account all these reactions. Thus, pyrolysis is typically studied through hypothetical [5] models, in which the overall pyrolysis behavior is considered as the combination of each individual component [6,7]. Moreover, the kinetic study attempts to unravel how the thermal decomposition takes place (whether one or more processes and what range of conversions occur) through the characteristic kinetic constants provided by the kinetic models. This is critical to the design, build and operation of a large-scale reactor for pyrolysis of the apple pomace biomass, subject of the present study. Kinetic analysis of the thermal decomposition of biomass is generally based on the rate equation of decomposition of solids [8]: da Ea ¼ A exp f ðaÞ dt RT

(1)

where t denotes time, a indicates the fraction of sample that has reacted and the degree of conversion, da/dt is the rate of the process, A and Ea are the pre-exponential factor and the activation energy, respectively, from the Arrhenius equation f(a) is a conversion function that represents the reaction model used and depends on the controlling mechanism. In this study, the degree of conversion, a, is defined as: a¼

W0 W W0 Wf

(2)

where w0, wf and w are the sample masses at the beginning, end, and at a specific time t, respectively. The unknown terms in equation (1) are the formal kinetic parameters (A, Ea and f(a)) which are used to characterize biomass pyrolysis reactions [9]. For non-isothermal reactions, where the heating rate, b ¼ dT/dt is constant, the above equation may be expressed as: da da Ea ¼b ¼ A exp f ðaÞ (3) dt dT RT The techniques developed for the evaluation of the kinetic parameters for non-isothermal thermogravimetric analysis can be divided into fitting models and free models. With the free model is not necessary to assume a kinetic reaction, while kinetic parameters are obtained as a function of conversion or temperature. Within such models there are the iso-conversional methods, which assume a constant degree of conversion, and therefore the reaction rate depends only on the temperature. Thus, these methods allow the estimation of the activation energy, Ea as a function of conversion, a, and independently of the reaction model, f(a). The TGA data processing of iso-conversional methods can be either differential or integral. This paper presents results from a differential (Friedman) and two integral; FlynneWalleOzawa (FWO) and KissingereAkahiraeSunose (KAS) methods. The Friedman iso-conversional method is a differential technique, which involves taking natural logarithms of both sides of equation (3) [10],: da da Ea ¼ b ¼ ln½Af ðaÞ ¼ ln dt dT RT

(4)

It is assumed that the conversion function f(a) remains constant, which means that the biomass degradation is

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temperature independent and depends exclusively on the rate of mass loss. A plot of ln(da/dt) versus 1/T for the same degree of conversion of data taken at various heating rates, will result in a series of lines with slopes equal to Ea/R for each value of conversion, a, at different heating rates. The FlynneWalleOzawa method (FWO) is an integral isoconversional technique where regrouping the terms of equation (4), and integrating these with respect to a and T variables and using the approximation of Doyle the following expression is obtained: Ea Ea 2:315 0:4567 ln bylog A Rg ðaÞ RT

(5)

Thus, in the FWO method the plot of log(AEa/Rg(a)) vs 1/T or ln(b) vs 1/T for different heating rates allows to obtain parallel lines for a fixed degree of conversion. The slope (0.4567Ea/R) of these lines is proportional to the apparent activation energy. If equal Ea values are obtained for different values of a, it can be assumed with certainty that there is a single reaction step. By contrast, a change in Ea with an increase in the conversion degree is indicative of a complex reaction mechanism [11]. Another widely used integral iso-conversional technique is the KissingereAkahiraeSunose (KAS) method, obtained from the CoatseRedfern approximation and based on the following equation [12,13]: b AR Ea (6) ln 2 ¼ ln T Ea gðaÞ RT Assuming that a has a fixed value, the activation energy (Ea) can be determined from the slope of the straight line obtained by plotting ln(b/T2) vs 1/T.

Results and Discussion Chemical analyses Table 1 presents results from the proximal, elemental and compositional analyses for apple pomace. From the results of Table 1 it can be seen that the apple pomace has a small amount of N (0.78%), while for the case of S, this could not be detected, which is advantageous because it minimizes the corrosion problems associated with the formation of acids in the process equipment [4]. It is also evident that the greatest elemental amount corresponds to carbon with a 47.98% followed by oxygen with 37.44%. Moreover, there is a low ash (3.4%) and a high volatile (81.32%) contents, characteristic of lignocellulosic materials, which makes this biomass very attractive for thermal degradation processes [9]. The lignocellulosic composition is typically of biomass, although it is important to notice its high cellulose content (47.49%). With respect to the mineral composition of the ashes the major contributions come from barium (37.75%) and titanium (17.51%).

Thermogravimetric analysis Experimental TGA curves obtained for the apple pomace under different heating rates are presented in Fig. 1. The

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Table 1 e Results from calorific power, proximal, elemental and compositional analyses for the APB. Parameter

Unit

Elemental Analysis C H N O S Compositional Analysis Cellulose Hemicellulose Lignin Proximate Analysis Moisture Fixed Carbon Volatile matter Ash Composition of ash Al B Ba Ca Cr Cu Fe K Mg Mn Na Ti V Zn Removable Ethanol Physical Properties Density Calorific Power

Magnitude

% % % % %

47.98 6.65 0.78 37.44 N.D

% % %

47.49 27.77 24.72

% % % %

8.87 6.41 81.32 3.40

% % % % % % % % % % % % % %

0.51 11.43 37.75 2.01 0.80 8.50 0.35 7.73 1.54 10.24 0.23 17.51 0.56 0.84

%

2.89

kg/m3 kJ/kg

1103 22,420

thermal decomposition of the apple pomace reveals two main regions attributed to the decomposition of cellulose and hemicellulose. The first decomposition mass loss that occurs at low temperatures can be associated to the process of pyrolysis of hemicellulose and at higher temperatures the 35

5 °C/min 10°C /min 15 °C/min 20 °C/min

30 25

Weight, %

weight loss is associated with decomposition of cellulose. Moreover, mass losses for the decomposition of lignin are not observed in this temperature range. Understanding of the volatilization of apple pomace is important because pyrolysis is the first step in a process of gasification or combustion [8]. Furthermore, in this TGA plot it is observed that the greatest amount of volatile material is produced at a heating rate of 5 C/min, which is the curve that ends its decomposition at a lower temperature (~540 C). When heating rate increases, the required time to reach a certain temperature value increases, enabling dehydration, depolymerization, carbonylation, carboxylation and transglycosylation reactions. As a consequence, the amount of devolatilized matter is increased. The obtained curves at different heating rates, after a certain decomposition stage at high heating rate, reach a common value typical of the mass solid residue [14]. The largest sample weight loss is located from a temperature range of 200e450 C, as can be observed in Fig. 1, and this can be attributed to the devolatilization process. Analyzing this behavior, according to the literature the weight loss that occurs at 200 C is related to the beginning of the lignin and hemicellulose pyrolysis contained in the apple pomace [15]. From 250 and up to approximately 350 C the high decomposition rate arises and in this region the maximum devolatilization of hemicellulose, cellulose and lignin is achieved. Remaining molecules of these compounds generate the next weight loss that corresponds to the temperature (up to 550 C) in which the reaction ends. Fig. 2 presents a TGA plot of the apple pomace biomass (APB) subjected to different particle size fractions at a heating rate of 10 C/min. In this Figure it can be observed that particle sizes smaller or equal than 150 mm are the ones that allow the generation of the greater amount of volatile matter. The difference in volatiles production with respect to the size of the particles is attributed to a main reason: particles greater than 425 mm, during the devolatilization process, some problems arise related to the heat and mass transfer [16], as reported by Lou and Stanmore [17].

20 15 10 5 0 0

100

200

300

400

500

600

700

800

900

Temperature, °C

Fig. 1 e TGA curves for the pyrolysis of apple pomace under N2 at different heating rates.

Fig. 2 e TGA curves for the pyrolysis of the apple pomace under N2 at a heating rate of 10 C/min and different particle sizes.

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Fig. 3 e DTGA curves for the pyrolysis of apple pomace under N2 at different heating rates.

The derivative of weight vs temperature plots for the different heating rates (b) of 5, 10, 15, 20 C/min for the apple pomace are shown in Fig. 3. In TGA and derivative thermogravimetric analysis (DTGA) from the pyrolysis of lignocellulosic materials typically, at least three peaks are observed, which can be associated to the cellulose,

1.0

5 °C/min

0.8

0.8

0.6

0.6

Conversion,

Conversion,

1.0

hemicellulose and lignin. Thus, indicating that although there appear interactions between fractions they usually overlap in their decomposition, while their identity is maintained [5]. Specifically, at temperatures below 200 C there is a small change in conversion of the sample and is this usually attributed to moisture removal, which is bonded to the surface of the sample. The apple pomace decomposition started around 250 C as shown in Figs. 1 and 2. While, in Fig. 3 a displacement of the curves to the right with the increase in heating rate is observed. This shift happened due to a greater reaction times that occurred at higher temperatures, In addition, the maximum decomposition rate tends to increase at higher heating rates, because a greater thermal energy is provided that facilitates the heat transfer around and within the samples [18]. Furthermore, TGA curves show that the major decomposition occurs between 220 and 600 C. Given the fact that the biomass contains mainly cellulose, hemicellulose, lignin and pectin, it has been found that cellulose decomposes between 277 and 427 C, hemicellulose around 197 and 327 C and lignin between 277 and 527 C [19]. Also, it can be observed that the decomposition of the pomace after 400 C proceeds at a slower rate because of the characteristic lignin decomposition rate [20].

0.4

0.2

0.0 200

10 °C/min

0.4

0.2

300

400

500

600

700

800

900

1000

0.0 200

1100

300

400

500

600

700

800

900

1.0

20 °C/min

0.8

0.8

0.6

0.6

Conversion,

Conversion,

1100

1.0

15 °C/min

0.4

0.2

0.0 200

1000

Temperature, K

Temperature, K

0.4

0.2

300

400

500

600

700

Temperature, K

800

900

1000

1100

0.0 200

300

400

500

600

700

Temperature, K

800

Fig. 4 e Isothermal residence time effect for the apple pomace (from 300 to 1070 K).

900

1000

1100

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Fig. 5 e Friedman differential model for the calculation of the activation energies of APB.

Kinetic analysis The thermal behavior of the apple pomace was studied through TGA in the temperature range of 300e1070 K. In Fig. 4 the change in conversion with temperature for all four heating

rates; 5, 10, 15 and 20 C/min in a nitrogen environment can be seen. These plots were used for the kinetic analysis based on the three kinetic models above described. According to the Friedman differential model, activation energy, Ea, based on equation (4) can be determined from a

Fig. 6 e FWO integral model for the calculation of the activation energies of APB.


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Fig. 7 e KAS integral model for the calculation of the activation energies of APB.

plot of ln[da/dt] versus 1/T and results are presented in Fig. 5. Here, the slopes of the iso-conversional lines give (Ea/R) at progressing conversion degrees a. Activation energy has also been calculated using the integral FWO method using equation (5) and Fig. 6 presents the iso-conversional linear plots of ln(b) versus 1/T where slopes give 0.453 Ea/R at progressing conversion degrees for this method. Finally, Fig. 7 shows results for the integral KAS method using the equation (6) where linear plots of ln(ß/T2) versus 1/T provide slopes to determine (Ea/R) at progressing conversion degrees a. The calculated activation energies for the Friedman, OFW and KAS methods are presented in Table 2. Because of low correlation values at conversion degrees below 0.2 and above 0.8 these values are not included [21]. The mean activation energies calculated from Friedman, OFW and KAS methods were 197.7, 213.0 and 201.7 kJ/mol, respectively. Also, excellent linear correlation coefficients were obtained with a R2 very close to 1 with 0.973, 0.996 and 0.978, for the Friedman,

OFW and KAS methods respectively. Results obtained from all models were in a good agreement with a deviation below 8%. The small deviations from the highest activation energy (OFW) with respect to the Friedman and KAS methods were 7.1 and 5.6%, respectively, which validate the reliability of calculations and confirmed the predictive power of KAS and OFW methods [22]. Kinetic analysis results showed that activation energy is highly depended on conversion which means that the apple pomace pyrolysis is a complex process consisting of several reactions. Fig. 8 shows the change in activation energy with respect to progressing conversions. For the calculated values from Friedman, FWO and KAS models Ea increases from 0.2 to 0.5 conversions. While, all the models follow almost the same increasing Ea trend with respect to conversion, and they peak at a conversion around a ¼ 0.49. Different reaction mechanisms are responsible for the change in Ea values as conversion increases. Due to the fact that activation energy is the

Table 2 e Activation energy results as a function of (a) for the Friedman, FWO and KAS kinetic models. Conversion (a) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

E, model KAS, kJ/mol

R2

E, model FWO, kJ/mol

R2

E, model Friedmann, kJ/mol

R2

137 189 228 237 280 170 134 174 105

0.9984 0.9967 0.9954 0.9963 0.9732 0.9589 0.9661 0.9596 0.9501

145 198 238 247 290 182 189 147 119

0.9969 0.9957 0.9959 0.9958 0.9916 0.9987 0.9975 0.9994 0.9825

148 213 235 249 267 175 145 100 78

0.9966 0.9963 0.9863 0.9994 0.9764 0.9575 0.9467 0.9469 0.904

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Fig. 8 e Activation energy as a function of progressing conversions (a) for the Friedman, FWO and KAS kinetic models.

minimum energy required for a reaction to begin, the higher the Ea values the slower reactions will proceed. Furthermore Ea is also employed in the calculation of the reactivity of a fuel [23]. Gai et al. reported the kinetic mechanism of rice husk and corn cob and calculated Ea values of 79 and 129 kJ/mol, respectively. Damartzis et al. [21] studied the pyrolysis kinetics of cardoon and found an Ea ¼ 224.1 kJ/mol for cardoon stems and 350.07 kJ/mol for cardoon leaves. LopezeVelazquez et al. [22], reported Ea values for pyrolysis of orange waste between 120 and 250 kJ/mol. Amutio et al. [24] studied pinewood waste pyrolysis kinetics and found that Ea changed between 62 and 206 kJ/mol. In general, calculated Ea values for apple pomace was similar to those reported in previous waste biomass studies. Moreover, the values of activation energy obtained in the present research for the models applied are within the range of values of activation energy of hemicellulose (67e105 kJ/ mol), cellulose (210e240 kJ/mol) and lignin (65e67 kJ/mol) [25]. Huang et al. [25] have studied the evolution of the activation energy values as a function of the degree of conversion, finding lower Ea values for small conversions, a growth of

these at intermediate conversions to return to low values towards the end. These authors have related this behavior to the decomposition of the hemicellulose, cellulose and lignin fractions. Since, Ea values obtained in these conversion ranges are close to the tabulated values of the pure compounds. However, it should be noted that the activation energy values that are determined for any conversion value should not be considered as the actual values of a particular reaction step, but as an apparent value that represents the contributions of numerous parallel and competing reactions, which contribute to the overall reaction rate. For such a complex biomass devolatilization process, the contributions will vary with the temperature and the conversion and very often overlap one another [26,27]. In order to validate the kinetic parameters, the preexponential factors as a function of conversion were determined using CoatseRedfern method [28,29]. Since the KAS method is more reliable, activation energies obtained from this model was used in the CoatseRedfern equations for calculation of the pre-exponential factor. Calculated pre-exponential factor values are shown in Table 3. It is important to notice

Table 3 e Pre-exponential calculation results as a function of (a) and (b) for the KAS kinetic model. Conversion (a) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

b ¼ 5 C/min

b ¼ 10 C/min

b ¼ 15 C/min

b ¼ 20 C/min

0.000292856 0.000574277 0.000858529 0.001174112 0.001518704 0.001783433 0.002189155 0.002781244 0.003803871

0.000585713 0.001148554 0.001717057 0.002348223 0.003037408 0.003566865 0.004378311 0.005562487 0.007607743

0.000878569 0.001722831 0.002575586 0.003522335 0.004556113 0.005350298 0.006567466 0.008343731 0.011411614

0.00087857 0.00172283 0.00257559 0.00352234 0.00455611 0.0053503 0.00656747 0.00834373 0.01141161


that in the CoatseRedfern model the pseudo-order n, has no physical meaning and therefore this parameter was not calculated in the present research. Finally, it is important to notice that the present study is the first report on apple pomace biomass (APB) pyrolysis kinetics and the obtained midactivation energy values for APB makes it an attractive energetic waste biomass for a waste-to-energy potential fuel.

Conclusion In this study the pyrolysis of waste apple pomace biomass (APB) has been investigated for the first time by means of thermogravimetric analysis. The low moisture and ash content and high volatile matter makes apple pomace a high potential candidate for production of bio-chemicals and with further processing for hydrogen production. Apple pomace pyrolysis kinetics using data obtained from TGA analysis showed good agreement with experimental data. This kinetic data will be an important tool to model, design and develop a thermochemical system for apple pomace in the near future. The results of this study are crucial as they provide many options for future application of APB as a waste-to-energy resource for energy and chemicals.

Acknowledgments This research was supported by Consejo Nacional de Ciencia y xico) Tecnologıá (CONACYT-Me

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