# Pyrolytic Characteristics and Kinetics ofPhragmites australis

Authors: Hui Zhao; Huaxiao Yan; Congwang Zhang; Xiaodong Liu; Yanhui Xue; Yingyun Qiao; Yuanyu Tian; Song Qin
Journal: Evidence-Based Complementary and Alternative Medicine
 (2011)

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## Abstract

The pyrolytic kinetics ofPhragmites australis was investigated using thermogravimetric analysis (TGA) method with linear temperature programming process under an inert atmosphere. Kinetic expressions for the degradation rate in devolatilization and combustion steps have been obtained for P. australis with Dollimore method. The values of apparent activation energy, the most probable mechanism functions, and the corresponding preexponential factor were determined. The results show that the model agrees well with the experimental data and provide useful information for the design of pyrolytic processing system using P. australis as feedstock to produce biofuel.


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## Body

## 1. Introduction

The common reed,Phragmites australis (Cav.) Trin. exSteud., described as one of the most widely distributed angiosperms [1, 2] is commonly found in freshwater and marine wetlands and along the upland edge of tidal marshes. P. australis has increased in proportion in both tidal and nontidal wetlands in North America and has become a major concern to wetland ecologists [3, 4]. Expansion of P. australis into salt marshes reportedly caused a fivefold decrease in plant species richness [5], reductions in microtopography [6, 7], and reductions in biodiversity [3]. P. australis is actively colonizing wetlands raising concern about loss of biodiversity [8, 9]. In addition, the alternative source of energy contributes to the reduction of CO2 emissions since the same amount of CO2 is extracted from the air during the growth period of the plants [10]. P. australis seems to be especially a promising energy plant and chemical feedstock due to its high production potential. Various processes have been proposed for the integrated utilization of these powerful plants [11, 12]. The common reed can provide a large quantity of biomass and annual yields of 40–63 tons per hectare have been reported. P. australis is becoming very important as stable biomass source for China with its natural huge reserves and increasing artificial cultivation.Pyrolysis is an effective method to harvest the energy inP. australis. However, pyrolytic characteristics studies of P. australis are little, which has led to the production of biofuel being far from commercialization. Both the development of the pyrolytic process and reactor design require complete elucidation of the pyrolytic mechanism. Therefore, the pyrolytic mechanisms of P. australis should be studied.The specific objective of the present work was to study the pyrolytic characteristics ofP. australis using a TG/DSC instrument. The kinetic parameters of decomposition were then obtained and the pyrolytic mechanism was illustrated, which can provide useful information for the design of pyrolysis system using P. australisbiomass as feedstock to produce bio-fuel.


## 2. Materials and Methods

### 2.1. Materials

P. australissamples were harvested from a wetland beside the campus of Shandong University of Science and Technology, Qingdao, China, September 2010.


### 2.2. Analysis ofP. australis Samples

Samples were ground into fine powders and sieved to less than 0.147 mm. Proximate and ultimate analyses were carried out to characterizeP. australis samples according to national standard GB212-91 (China) and element analyzer (Elementar Analysensysteme GmbH vario EL cube), respectively. In addition, cellulose, hemicelluloses, and lignin contents were analyzed according to methods from the literature [13]. The results were summarized in Table 1. All tests were carried out in triplicate.Table 1
Proximate analysis, ultimate analysis, and component analysis ofP. australis (/%wt).
ParameterP. australisProximate analysisa (wt.%, ad. Basis)Moisture5.89 ± 0.03Ash12.32 ± 1.12Volatile matter70.01 ± 2.40Fix carbonc11.78Ultimate analysisb (wt.%, daf. Basis)Carbon42.78 ± 1.53Hydrogen5.17 ± 0.02Oxygenc50.511Nitrogen1.31 ± 0.02Sulfur0.229 ± 0.01C/H8.31 ± 0.31C/N32.57 ± 1.55Component analysis(wt.%, daf. Basis)Hemicellulose30.68 ± 3.15Lignin20.34 ± 1.56Cellulose43.05 ± 3.98aDry-free basis; bDry ash-free basis;  cCalculated by difference.


### 2.3. Pyrolysis of the Samples

Thermogravimetric analyses were carried out using a thermal analyzer (TGA/DSC1/1600LF, METTLER TOLEDO Co., Switzerland). 10 mg of initial sample was pyrolyzed under a nitrogen flow rate of 50 cm3/min with a heating rate of 25°C/min. The weight loss and calorific changes in response to temperature were then recorded and used to plot the thermogravimetric analysis (TGA), derivative thermogravimetric analysis (DTG), and differential scanning calorimetric (DSC) curves. All experiments were replicated three times.


### 2.4. The Kinetic Parameters of the Samples

(1)dαdt=κf(α),
where α is the conversion rate and is defined as(2)α=m0-mm0-m∞,κ is the velocity constant, and f(α) is the mechanism function with different relative coefficient(3)T=T0+βt,
where β is the heating rate andT0 is the initial temperature.The reaction rate constant,κ, can be described by the following expression:
(4)κ=CTm.
By separation of variables and integration, (5)G(α)=∫0αdαf(α)=Cβ∫T0TTmdT=Cβ(m+1)Tm+1+D=BTm+1+D⇄D=0BTm+1.
The expression of G(α) corresponding to each one of the mechanisms considered is also shown in Table 2(6)lgG(αi)=lgB+(m+1)lgTi.Table 2
Algebraic expressions of functionsG(α) and f(α) and mechanisms [23, 24].
No.G(a)f(α)Rate-determining mechanism11-(1-α)2/33/2(1-α)1/3Chemical reaction21-(1-α)1/44(1-α)3/4Chemical reaction3(1-α)-1/2-12(1-α)3/2Chemical reaction4(1-α)-1-1(1-α)2Chemical reaction5(1-α)2-11/2(1-α)3Chemical reaction6(1-α)3-11/3(1-α)4Chemical reaction71-(1-α)21/2(1-α)Chemical reaction81-(1-α)31/3(1-α)2Chemical reaction91-(1-α)41/4(1-α)3Chemical reaction10α3/22/3α-1/2Nucleation11α1/22α1/2Nucleation12α1/33α2/3Nucleation13α1/44α3/4Nucleation14lnaαNucleation15-ln(1-α)1-αAssumed random nucleation and its subsequent growth16[-ln(1-α)]2/33/2(1-α)[-ln(1-α)]1/3Assumed random nucleation and its subsequent growth17[-ln(1-α)]1/22(1-α)[-ln(1-α)]1/2Assumed random nucleation and its subsequent growth18[-ln(1-α)]1/33(1-α)[-ln(1-α)]2/3Assumed random nucleation and its subsequent growth19[-ln(1-α)]1/44(1-α)[-ln(1-α)]3/4Assumed random nucleation and its subsequent growth20[-ln(1-α)]21/2(1-α)[-ln(1-α)]-1Assumed random nucleation and its subsequent growth21[-ln(1-α)]31/3(1-α)[-ln(1-α)]-2Assumed random nucleation and its subsequent growth22[-ln(1-α)]41/4(1-α)[-ln(1-α)]-3Assumed random nucleation and its subsequent growth23lna/(1-α)a/(1-a)Branching nuclei24α(1-a)0Contracting disk251-(1-α)1/22(1-a)1/2Contracting cylinder (cylindrical symmetry)261-(1-α)1/33(1-a)2/3Contracting sphere (spherical symmetry)27α21/(2a)One-dimensional diffusion28[1-(1-α)1/2]1/24{(1-α)[1-(1-α)]1/2}1/2Two-dimensional diffusion29a+(1-α)ln(1-α)[-ln(1-α)]-1Two-dimensional diffusion30[1-(1-α)1/3]2(3/2)(1-α)2/3[1-(1-α)1/3]-1Three-dimensional diffusion, spherical symmetry311-2/3α-(1-α)2/3(3/2)[(1-αa)-1/3-1]-1Three-dimensional diffusion, cylindrical symmetry32[(1-α)-1/3-1]2(3/2)(1-α)4/3[(1-α)-1/3-1]-1Three-dimensional diffusion33[(1+α)1/3-1]2(3/2)(1+α)2/3[(1+α)1/3-1]-1Three-dimensional diffusion341+2/3α-(1+α)2/3(3/2)[(1+α)-1/3-1]-1Three-dimensional diffusion35[(1+α)-1/3-1]2(3/2)(1+α)4/3[(1+α)-1/3-1]-1Three-dimensional diffusion36[1-(1-α)1/3]1/26(1-α)2/3[1-(1-α)1/3]1/2Three-dimensional diffusionThis equation is used to estimate the most correct reaction mechanism functionG(α). According to the plotting lgG(αi) versus lgTi and a linear regression, if the mechanism studied conforms to certain G(α) function, the slope of the straight line should be equal to −1.00000 and the linear correlation coefficient R2 is high(7)B=Cβ(m+1).
Both of (5) and (6) are called Harcourt-Fission model of integral. m and B were constructed with deducing coefficients of least-square method(8)lgκi=lgC+mlgTi.
With a given value of lgTi, the constants C, m, lgκican be determined(9)ln⁡κi=ln⁡A-ERTi.
Substituting the value of lnκi back into (9) in conjunction with 1/T allows lnA and E to be calculated [14].All plots were generated and the lines were fitted using the Origin 8.0 software.


## 2.1. Materials

P. australissamples were harvested from a wetland beside the campus of Shandong University of Science and Technology, Qingdao, China, September 2010.


## 2.2. Analysis ofP. australis Samples

Samples were ground into fine powders and sieved to less than 0.147 mm. Proximate and ultimate analyses were carried out to characterizeP. australis samples according to national standard GB212-91 (China) and element analyzer (Elementar Analysensysteme GmbH vario EL cube), respectively. In addition, cellulose, hemicelluloses, and lignin contents were analyzed according to methods from the literature [13]. The results were summarized in Table 1. All tests were carried out in triplicate.Table 1
Proximate analysis, ultimate analysis, and component analysis ofP. australis (/%wt).
ParameterP. australisProximate analysisa (wt.%, ad. Basis)Moisture5.89 ± 0.03Ash12.32 ± 1.12Volatile matter70.01 ± 2.40Fix carbonc11.78Ultimate analysisb (wt.%, daf. Basis)Carbon42.78 ± 1.53Hydrogen5.17 ± 0.02Oxygenc50.511Nitrogen1.31 ± 0.02Sulfur0.229 ± 0.01C/H8.31 ± 0.31C/N32.57 ± 1.55Component analysis(wt.%, daf. Basis)Hemicellulose30.68 ± 3.15Lignin20.34 ± 1.56Cellulose43.05 ± 3.98aDry-free basis; bDry ash-free basis;  cCalculated by difference.


## 2.3. Pyrolysis of the Samples

Thermogravimetric analyses were carried out using a thermal analyzer (TGA/DSC1/1600LF, METTLER TOLEDO Co., Switzerland). 10 mg of initial sample was pyrolyzed under a nitrogen flow rate of 50 cm3/min with a heating rate of 25°C/min. The weight loss and calorific changes in response to temperature were then recorded and used to plot the thermogravimetric analysis (TGA), derivative thermogravimetric analysis (DTG), and differential scanning calorimetric (DSC) curves. All experiments were replicated three times.


## 2.4. The Kinetic Parameters of the Samples

(1)dαdt=κf(α),
where α is the conversion rate and is defined as(2)α=m0-mm0-m∞,κ is the velocity constant, and f(α) is the mechanism function with different relative coefficient(3)T=T0+βt,
where β is the heating rate andT0 is the initial temperature.The reaction rate constant,κ, can be described by the following expression:
(4)κ=CTm.
By separation of variables and integration, (5)G(α)=∫0αdαf(α)=Cβ∫T0TTmdT=Cβ(m+1)Tm+1+D=BTm+1+D⇄D=0BTm+1.
The expression of G(α) corresponding to each one of the mechanisms considered is also shown in Table 2(6)lgG(αi)=lgB+(m+1)lgTi.Table 2
Algebraic expressions of functionsG(α) and f(α) and mechanisms [23, 24].
No.G(a)f(α)Rate-determining mechanism11-(1-α)2/33/2(1-α)1/3Chemical reaction21-(1-α)1/44(1-α)3/4Chemical reaction3(1-α)-1/2-12(1-α)3/2Chemical reaction4(1-α)-1-1(1-α)2Chemical reaction5(1-α)2-11/2(1-α)3Chemical reaction6(1-α)3-11/3(1-α)4Chemical reaction71-(1-α)21/2(1-α)Chemical reaction81-(1-α)31/3(1-α)2Chemical reaction91-(1-α)41/4(1-α)3Chemical reaction10α3/22/3α-1/2Nucleation11α1/22α1/2Nucleation12α1/33α2/3Nucleation13α1/44α3/4Nucleation14lnaαNucleation15-ln(1-α)1-αAssumed random nucleation and its subsequent growth16[-ln(1-α)]2/33/2(1-α)[-ln(1-α)]1/3Assumed random nucleation and its subsequent growth17[-ln(1-α)]1/22(1-α)[-ln(1-α)]1/2Assumed random nucleation and its subsequent growth18[-ln(1-α)]1/33(1-α)[-ln(1-α)]2/3Assumed random nucleation and its subsequent growth19[-ln(1-α)]1/44(1-α)[-ln(1-α)]3/4Assumed random nucleation and its subsequent growth20[-ln(1-α)]21/2(1-α)[-ln(1-α)]-1Assumed random nucleation and its subsequent growth21[-ln(1-α)]31/3(1-α)[-ln(1-α)]-2Assumed random nucleation and its subsequent growth22[-ln(1-α)]41/4(1-α)[-ln(1-α)]-3Assumed random nucleation and its subsequent growth23lna/(1-α)a/(1-a)Branching nuclei24α(1-a)0Contracting disk251-(1-α)1/22(1-a)1/2Contracting cylinder (cylindrical symmetry)261-(1-α)1/33(1-a)2/3Contracting sphere (spherical symmetry)27α21/(2a)One-dimensional diffusion28[1-(1-α)1/2]1/24{(1-α)[1-(1-α)]1/2}1/2Two-dimensional diffusion29a+(1-α)ln(1-α)[-ln(1-α)]-1Two-dimensional diffusion30[1-(1-α)1/3]2(3/2)(1-α)2/3[1-(1-α)1/3]-1Three-dimensional diffusion, spherical symmetry311-2/3α-(1-α)2/3(3/2)[(1-αa)-1/3-1]-1Three-dimensional diffusion, cylindrical symmetry32[(1-α)-1/3-1]2(3/2)(1-α)4/3[(1-α)-1/3-1]-1Three-dimensional diffusion33[(1+α)1/3-1]2(3/2)(1+α)2/3[(1+α)1/3-1]-1Three-dimensional diffusion341+2/3α-(1+α)2/3(3/2)[(1+α)-1/3-1]-1Three-dimensional diffusion35[(1+α)-1/3-1]2(3/2)(1+α)4/3[(1+α)-1/3-1]-1Three-dimensional diffusion36[1-(1-α)1/3]1/26(1-α)2/3[1-(1-α)1/3]1/2Three-dimensional diffusionThis equation is used to estimate the most correct reaction mechanism functionG(α). According to the plotting lgG(αi) versus lgTi and a linear regression, if the mechanism studied conforms to certain G(α) function, the slope of the straight line should be equal to −1.00000 and the linear correlation coefficient R2 is high(7)B=Cβ(m+1).
Both of (5) and (6) are called Harcourt-Fission model of integral. m and B were constructed with deducing coefficients of least-square method(8)lgκi=lgC+mlgTi.
With a given value of lgTi, the constants C, m, lgκican be determined(9)ln⁡κi=ln⁡A-ERTi.
Substituting the value of lnκi back into (9) in conjunction with 1/T allows lnA and E to be calculated [14].All plots were generated and the lines were fitted using the Origin 8.0 software.


## 3. Results and Discussion

### 3.1. Characterization of Materials

The results of proximate, ultimate, and component analysis ofP. australis samples are summarized in Table 1, which is in the same order of magnitude as energy crops. The comparison with other terrestrial materials shows a higher amount of ash and cellulose. The volatile matter and lignin contents of P. australis are lower, respectively, while the sulfur content of the samples is approximately equal [15].


### 3.2. Characteristics of the Thermal Degradation Process

Three stages in the pyrolytic process ofP. australis are in accordance with the conclusion of oxidative pyrolysis curves of energy crops followed the usual shape for lignocellulosic materials [16–19]. The first stage (I) occurred as the temperature increased from 50 to 240°C, losing cellular water and the external water bound by surface tension. While the second stage (II), occurring as the temperature increased from 240 to 500°C was the devolatilization stage, during which the main pyrolytic process occurred and most of the organic materials are decomposed accompanied by various volatile components released gradually, resulting in a large weight loss which is more than 50% of total volatiles and formation of the main pyrolytic production. Specifically, stage II was composed of two zones for P. australis due to the different thermal stability of the components with zone I occurring as the temperature increased from 240 to 318°C which is a strong peak in the rate of weight loss curve, at which the rate of weight loss attains maximum with a maximum weight loss point at 288°C and zone II occurred as the temperature increased from 318 to 500°C with a maximum weight loss point at 346°C. The third stage (III) occurred as the temperature increased from 500 to 800°C with the residuals, the carbonaceous matters in the solid, slowly decomposed, resulting in the formation of a loose porous residual. A slight continued loss of weight is shown in the weight loss curve. P. australis is composed of many polysaccharides that have low polymerization. Moreover, the inorganic salts in P. australis presented a catalytic effect [20]. These findings indicate that the beginning of the decomposition occurs at a higher temperature for the samples evaluated in this study than for other terrestrial biomass with a high content of cellulose (straws and grasses) or lignin (woody biomass).The weight losses ofP. australis during stage I are primarily due to the loss of moisture and are similar to the moisture content values reported in Table 1. The instantaneous maximum reaction rate occurred in zone I of stage II. There was an endothermic peak during stage I that corresponded with the moisture evaporation procedure. As the temperature increased, an exothermic effect appeared during stage II and exothermic peaks were observed at 5–15°C after the maximum weight loss point. These findings indicate that the devolatilization stage (stage II) produced heat. Specifically, there was an endothermic effect during stage III. These findings indicate that the carbonaceous residual may have been decomposed at temperatures above 600°C. A maximum exothermic peak corresponding to the maximum weight loss rate peak appeared on the DSC curve of the samples (stage II). These findings indicate that the main pyrolysis process of the samples is an exothermic process. The exothermic effect was due to the charring process, which is the decomposition of the inorganic materials to metal carbonate (Figures 1, 2, and 3) [21, 22].Figure 1
TG-DTG curves ofP. australis.Figure 2
DSC curves ofP. australis.Figure 3
Plot for determination of most probable mechanism functions.


### 3.3. Kinetic Analysis of the Pyrolysis Process

The most probable mechanism function with integral form can be expressed byG(α3)=(1-α)1/2-1,(10)m+1=n∑i=1nlgG(αi)lgTi-∑i=1nlgTi∑i=1nlgG(αi)n∑i=1nTi2-∑i=1nTi∑i=1nTi,lgB=∑i=1nTiG(αi)∑i=1nTi-∑i=1nG(αi)∑i=1nTi2∑i=1nTi∑i=1nTi-n∑i=1nTi2,
and the results calculated according to the above equations are as follows: lgB=-116.34877, m=41.18814, and lgC=-113.32564.The result indicates that the model is in good agreement with the experimental data (Figure4).Figure 4
Plot for determination ofE and A(lnA= 25.14 min−1, E= 162.66 kJ mol−1, R2  = 0.9999).Comparisons of the decomposition temperature and activation energy of several types of biomass are provided in Table3 [17]. The results indicate that the decomposition temperature of P. australis is lower than that of several kinds of plants and single component of biomass.Table 3
Comparison of various kinetic parameters of pyrolysis for different biomass[17, 25].
SamplesDecomposition temperature (°C)Activation energy(kJ mol−1)Cellulose300–430200Hemicellulose250–350100Lignin250–55080Chitosan268–31295.6–185.7Enteromorpha prolifera174–551228.1spirulina platensis190–56076.2–97Chlorella protothecoides150–54042.2–52.5Dunaliella tertiolecta155–299145.713–146.421Oak tree230–400236.2Corn stover250–47057.95–58.94Peat208–33452.77P. australis240–500163


## 3.1. Characterization of Materials

The results of proximate, ultimate, and component analysis ofP. australis samples are summarized in Table 1, which is in the same order of magnitude as energy crops. The comparison with other terrestrial materials shows a higher amount of ash and cellulose. The volatile matter and lignin contents of P. australis are lower, respectively, while the sulfur content of the samples is approximately equal [15].


## 3.2. Characteristics of the Thermal Degradation Process

Three stages in the pyrolytic process ofP. australis are in accordance with the conclusion of oxidative pyrolysis curves of energy crops followed the usual shape for lignocellulosic materials [16–19]. The first stage (I) occurred as the temperature increased from 50 to 240°C, losing cellular water and the external water bound by surface tension. While the second stage (II), occurring as the temperature increased from 240 to 500°C was the devolatilization stage, during which the main pyrolytic process occurred and most of the organic materials are decomposed accompanied by various volatile components released gradually, resulting in a large weight loss which is more than 50% of total volatiles and formation of the main pyrolytic production. Specifically, stage II was composed of two zones for P. australis due to the different thermal stability of the components with zone I occurring as the temperature increased from 240 to 318°C which is a strong peak in the rate of weight loss curve, at which the rate of weight loss attains maximum with a maximum weight loss point at 288°C and zone II occurred as the temperature increased from 318 to 500°C with a maximum weight loss point at 346°C. The third stage (III) occurred as the temperature increased from 500 to 800°C with the residuals, the carbonaceous matters in the solid, slowly decomposed, resulting in the formation of a loose porous residual. A slight continued loss of weight is shown in the weight loss curve. P. australis is composed of many polysaccharides that have low polymerization. Moreover, the inorganic salts in P. australis presented a catalytic effect [20]. These findings indicate that the beginning of the decomposition occurs at a higher temperature for the samples evaluated in this study than for other terrestrial biomass with a high content of cellulose (straws and grasses) or lignin (woody biomass).The weight losses ofP. australis during stage I are primarily due to the loss of moisture and are similar to the moisture content values reported in Table 1. The instantaneous maximum reaction rate occurred in zone I of stage II. There was an endothermic peak during stage I that corresponded with the moisture evaporation procedure. As the temperature increased, an exothermic effect appeared during stage II and exothermic peaks were observed at 5–15°C after the maximum weight loss point. These findings indicate that the devolatilization stage (stage II) produced heat. Specifically, there was an endothermic effect during stage III. These findings indicate that the carbonaceous residual may have been decomposed at temperatures above 600°C. A maximum exothermic peak corresponding to the maximum weight loss rate peak appeared on the DSC curve of the samples (stage II). These findings indicate that the main pyrolysis process of the samples is an exothermic process. The exothermic effect was due to the charring process, which is the decomposition of the inorganic materials to metal carbonate (Figures 1, 2, and 3) [21, 22].Figure 1
TG-DTG curves ofP. australis.Figure 2
DSC curves ofP. australis.Figure 3
Plot for determination of most probable mechanism functions.


## 3.3. Kinetic Analysis of the Pyrolysis Process

The most probable mechanism function with integral form can be expressed byG(α3)=(1-α)1/2-1,(10)m+1=n∑i=1nlgG(αi)lgTi-∑i=1nlgTi∑i=1nlgG(αi)n∑i=1nTi2-∑i=1nTi∑i=1nTi,lgB=∑i=1nTiG(αi)∑i=1nTi-∑i=1nG(αi)∑i=1nTi2∑i=1nTi∑i=1nTi-n∑i=1nTi2,
and the results calculated according to the above equations are as follows: lgB=-116.34877, m=41.18814, and lgC=-113.32564.The result indicates that the model is in good agreement with the experimental data (Figure4).Figure 4
Plot for determination ofE and A(lnA= 25.14 min−1, E= 162.66 kJ mol−1, R2  = 0.9999).Comparisons of the decomposition temperature and activation energy of several types of biomass are provided in Table3 [17]. The results indicate that the decomposition temperature of P. australis is lower than that of several kinds of plants and single component of biomass.Table 3
Comparison of various kinetic parameters of pyrolysis for different biomass[17, 25].
SamplesDecomposition temperature (°C)Activation energy(kJ mol−1)Cellulose300–430200Hemicellulose250–350100Lignin250–55080Chitosan268–31295.6–185.7Enteromorpha prolifera174–551228.1spirulina platensis190–56076.2–97Chlorella protothecoides150–54042.2–52.5Dunaliella tertiolecta155–299145.713–146.421Oak tree230–400236.2Corn stover250–47057.95–58.94Peat208–33452.77P. australis240–500163


## 4. Conclusions

High priority should be given to the development and protection of biomass pyrolysis which is widely recognized as a technically and economically feasible way. This study presents useful information for the design of a pyrolytic processing system usingP. australisbiomass.(i)
There were three stages in the pyrolytic process of the samples. The second stage is the main pyrolysis process and most of the organic materials are decomposed in this stage which is our study focused on.(ii)
Iterative isoconversional procedure has been applied to estimate the values of apparent activation energy. The method of Dollimore combined with 36 mechanism functions is used to define the most probable mechanismG(α3)=(1-α)-1/2-1; the preexponential factor A= 8.28 × 1010 min−1 and E= 1.63 × 105 J mol−1 are obtained on the basis of G(α).(iii)
Comparisons of various kinetic parameters of pyrolysis for different biomass types show thatP. australisbiomass has a great potential and a good prospect for producing biofuel by fast pyrolysis process.To learn more aboutP. australis pyrolysis, characterization of liquid and solid products should be more in-depth understood [26, 27].



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