Tar Decomposition over a Porous Iron Ore Catalyst: Experiment and

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Catalysis and Kinetics

Tar Decomposition over porous iron ore catalyst: experiment and kinetic analysis Rochim Bakti Cahyono, Muslikhin Hidayat, Takahiro Nomura, Naoto Yasuda, and Tomohiro Akiyama Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b00814 • Publication Date (Web): 17 May 2018 Downloaded from http://pubs.acs.org on May 17, 2018

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Tar decomposition over porous iron ore catalyst: experiment and kinetic analysis Rochim B. Cahyonoa,*, Muslikhin Hidayata, Naoto Yasudab, Takahiro Nomurab, Tomohiro Akiyamab a

Department of Chemical Engineering, Universitas Gadjah Mada, JI. Grafika 2, Bulaksumur,

Yogyakarta 55281, Indonesia b

Center for Advanced Research of Energy Conversion Materials, Hokkaido University, North 13

West 8, Kita-ku, Sapporo 060-8628, Japan

*CORRESPONDING AUTHOR Tel: +62 274 902171; Fax: +62 274 902170 E-mail: [email protected]

ACS Paragon Plus Environment

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ABSTRACT In the pyrolysis process, tar material may cause operational problems such as pipe plugging, condensation, and tar aerosol formation. Unusual approaching should be introduced to solve carbon deposition over catalyst which was serious problem in tar decomposition process. The kinetic analysis was evaluated in detail by the proposed system, tar decomposition over porous catalyst of iron ore. Decomposition of lignite tar exhibited similar profiles of H2 and CO generation which was rising shortly at beginning of reaction because ore catalyst still owned high activity and no carbon poisoning. However, the excessive carbon deposition was also occurred simultaneously. Both kinetic constant and deactivation factor were evaluated successfully using simple proposed model with range of 0.1275 – 0.5523 s-1 and 1.7206 – 2.5310 s-1, respectively at 500-700oC. The activation energy was also calculated based on the Arrhenius equation which was 44.86 kJ/mol. The deactivation factor exhibited similar tendency with amount of carbon deposition within pores iron ore. It means that the carbon deposition within pores ore affected highly to catalyts activity. However, the high carbon content within inactive ore catalyst offered extra benefit in the steel production as raw material. Therefore, the tar decomposition over porous iron ore was promising catalyst which was cheap and abundant natural resource. In addition, this proposed system offered also solution for problems related with raw material, energy and environment in ironmaking industry. KEYWORDS: tar decomposition; kinetic analysis; carbon deposition; porous iron ore; ironmaking.


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1.

Introduction Pyrolysis is the main process for solid fuels utilization such as biomass and coal which

generate char, tar and gas product. As by-product, tar contains condensable organic material with high energy content but may cause operational problem such as pipe blocking, condensation, and tar aerosol formation.1-2 Therefore, complete decomposition of tar into a major fraction of the gaseous product that integrated with the reactor system is most essentials research subject in order to enhance the efficiency and cut the operation cost of the pyrolysis process. It is well known that complete decomposition of tar over several metal catalysts such as Ni, Pt, Rh, and Pd are promising method.3-8 Nickel catalysts in various types have been obtained to be highly effective for tar decomposition process in coal or biomass pyrolysis. For example, the NiMo catalyst almost removed 100% of tar material which contains mostly of methylnaphthalene hydrocarbon at 500oC.9 However, there is still very serious problem related with catalyst deactivation due to carbon deposition. Aznar et al observes that the catalyst activity of typical nickel A is drop into 54% during 35 h experiment time.10 Beside carbon deposition, high cost for raw material and regeneration method are another problems related with the conventional metal catalyst. In order to solve their problem, different approach was offered using certain material as catalyst that can still be used after the loss of activity. An example is the utilization of charcoal in the biomass pyrolysis for tar decomposition simultaneously and producing higher gas product.1114

The carbon deposition within charcoal which is resulted by tar decomposition enhances total

carbon content as well as heating value of charcoal. It has also been reported that iron-oxidebased catalysts such as Fe2O3-Al2O3 could be used effectively for tar decomposition to produce hydrogen.15-16 Natural goethite ore was useful for biomass tar decomposition to produce clean


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pyrolysis gas.17 The proposed system which consisted of integrated coal pyorlysis with tar decomposition over porous low grade ore (Fe2O3) is a promising method to solve the problems related to tar material and catalyst development.18-19 In this system, the volatile matter included tar material from pyrolysis is introduced to fixed bed of porous ore for decomposition process.20 The tar decomposition produces a high-value syngas (CO and H2), while at the same time the carbon deposits within the porous ore and causes catalyst deactivation. Thus, the clean gas product is generated with high values of H2 and CO which increases the energy efficiency of the pyrolysis process. In addition, the iron ore with high carbon deposition as inactive catalyst can act as reducing agent and cut the consumption of coke in ironmaking process. It’s reported that the inactive catalyst exhibited high reactivity and lower temperature in reduction reaction compared to conventional process.21 Therefore, the inactive iron ore catalyst could be excellent raw material in the ironmaking industry which contributes to address the problems about raw material, energy and environment.22 Among those great benefits, the understanding of the proposed system was highly required such as kinetic analysis and ore reduction behaviors. The effect of carbon deposition on the activity of catalyst in decomposition process was also still questionable. Consequently, this paper focuses on a detailed evaluation of the kinetic analysis in the proposed integrated coal pyrolysis-tar decomposition over porous iron ore. The comparison of kinetic parameters with the related experiments was also examined. In addition, the effect of carbon deposition on the catalyst activity was also discussed to further understand the lifetime of the catalyst.


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2 The proposed of kinetic model The kinetic model was proposed based on the decomposition of tar with the following reaction which was slightly modified from other reference.23 k HT  → f LT LT + f GS GS + f SC SC

(1)

The heavy tar (HT) decomposes into gaseous product (GS), solid carbon (SC), and light tar (LT) over porous ore. In the case of high catalyst activity, the light tar is also possible to decompose into gases and solid carbon. The coefficients fLT, fGS, and fSC correspond to the selectivities of light tar, gases and carbon respectively. By assuming the reaction is first-order kinetic, the reaction rate can be expressed as follow:

r = − k φ (t )CT y HT = f GS k φ (t )CT y HT = f SC k φ (t )CT y HT

(2)

where CT corresponds to total concentration of the reactant, yHT denotes the mass fraction of the heavy tar material, ϕ express the catalyst deactivation due to carbon deposition. Figure 1 shows the schematic fixed bed reactor which used for developing of the kinetic equations. By assumption the plug flow reactor, the mass balance of heavy tar through fixed bed reactor can be expressed with the differential equation:

∂y HT ∂y + u HT = −kφ (t ) y HT ∂t ∂z By defining gas velocity, u =

(3)

z t Q and dimensionless variables, x = ; θ = , where Q is L tR A

volumetric gas flow rate, A indicates bed cross-section area, L represents total reactor length and tR means total reaction time. The equation (3) can be modified as follow:


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1 ∂y HT Q ∂y HT + = −kφ (θ ) y HT t R ∂θ AL ∂x The substitution of reactor volume, VR = AL and gas residence time,

(4)

τ=

AL into equation (4) Q

results the following equation:

τ ∂y HT ∂y HT + = −τ kφ (θ ) y HT t R ∂θ ∂x

(5)

In case of continuous system with appropriate gas flow rate, the gas residence time is a lot of smaller than reaction time; therefore the equation (5) could be expressed in the simple form:

∂y HT = −τ kφ (θ ) y HT ∂x

(6)

The equation (3.6) can be solved using boundary condition (BC) in the reactor entrance,

x = 0 → y HT = 1 , thus the mass balance equation of heavy tar is defined as follow: y HT = exp[− τ kφ (θ )x ]

(7)

Based on the similar method, the mass balance of gaseous product is also developed as the following form:

∂yGS = f GSτ kφ (θ ) y HT ∂x

(8)

By applying equation (7) and BC in the reactor entrance, x = 0 → y HT = 1 → y GS = 0 so the equation (8) can be rearranged:

y GS = f GSτ kφ (θ )

1 x exp [− τ kφ (θ )x ]0 − τ kφ (θ )


(9)

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Inserting of BC in the outlet reactor, x = 1 → y GS = y GS , the equation (9) can be modified in following form:

y GS = f GS [1 − exp [− τ k φ (θ )]] The catalyst deactivation is assumed as first order exponential function,

(10)

φ (θ ) = exp(− λθ )

where λ is deactivation factor due to carbon deposition. The equation (10) can be modified and rearranged in the form:

  y ln − ln1 − GS f GS  

  = ln (τ k ) − λθ 

(11)

The reaction rate constant and deactivation factor could be evaluated using experimental data of tar decomposition process by simple linear correlation.


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3. Materials and experimental methods 3.1 Materials Lignite coal tar was examined as raw material in the tar decomposition process over porous iron ore which originated from Japan ironmaking industry. The tar was derived from pyrolisis of Australian lignite coal which elemental and major components as shown in Table 1. A low-grade iron ore, pisolite, was employed as catalyst for decomposition of tar and storage of deposited carbon. As shown in Table 2, the amount of combined water within the ore allowed for creation of a porous material through simple dehydration process. The ore was crushed and sieved to attain a particle size less than 106 µm. In order to remove the combined water and create porous material, the iron ore was dehydrated at 450°C with a heating rate of 3°C/min and a holding time of 1 hr in the open atmosphere. The dehydration process was evaluated using BET measurement (Autosorb 6AG, Quantachrome) and XRD analysis (Miniflex, Rigaku) for characterization of surface area and iron ore material phase, respectively.

3.2 Experimental methods Figure 2 shows the schematic diagram of the experimental apparatus which consisted of HPLC pump, gas flow controllers, a tubular fixed-bed reactor, cold trap and micro gas chromatography (GC) for evaluating gas composition in the reactor downstream. The reactor was made from a transparent quartz tube with an inner diameter of 8mm which equipped with infrared heater and temperature controller. The fixed bed reactor was 250 mg of porous ore and supported by quartz wool for catalyst of tar decomposition and carbon deposition. In order to avoid the line plugging, the tar liquid (5%vol) was mixed by toluene in the certain amount to decrease the viscosity and allow for pumping system. Experiments were performed at constant atmospheric pressure and several different temperatures with a total N2 flow rate of 50 mL/min


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and reactor heating rate of 10 K/min. After the reactor temperature was constant at desired temperature, the liquid tar was pumped into top of the reactor with the flow of 0.25 ml/min. The decomposition of tar occurred over porous ore to produce gas, carbon and light tar. The reduction reaction and carbon deposition within pores ore also took place simultaneously in the fixed bed reactor. The gas product and remaining tar were allowed to flow through the cold trap was maintained at –73°C for ensuring complete separation on liquid and gas product. The gas product was evaluated using micro GC to determine the amount of H2, CO, CO2, and light hydrocarbon gases. In order to obtain clear data, the experiment result using mixed tar liquidtoluene was evaluated and compared to experiment using toluene only. The characterization of iron ore was performed by XRD analysis and BET measurement. The carbon content within the iron was also examined using CHNO elemental analysis to evaluate the tar carbon deposition.


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4. Results and Discussion 4.1 Effect of reaction time on tar decomposition and carbon deposition In the decomposition process, the tar material decomposed into gases, carbon and light hydrocarbon as stated in equation (12). Figure 3 shows the product comparison of tar decomposition for pure toluene and mixture of toluene and lignite tar.

Tar → H 2 + CO + CO 2 + CH 4 + other light hydrocarbon + C

(12)

The gas composition of both experiment showed similar tendency that H2 was predominant compared to other gasses. The high production of H2 was related to the chemical bonding which was easy to break tar component especially light hydrocarbon and produced H2 gas. Obviously, small addition of lignite tar into toluene resulted large different in gas and carbon products. The 5%vol of lignite tar within toluene mixture enhanced 58.65%vol of gas product and 36.73%mass of carbon deposition compared to pure toluene.

In addition, the mixed liquid tar-toluene

exhibited also different gas profile which rising in beginning of reaction time. It denoted that the adding of lignite tar within pure toluene caused significant improvement of hydrocarbon substance in the raw material of decomposition process. Therefore, the mixture could represent the lignite tar as raw material and utilized to evaluate the tar decomposition process and kinetic parameters. Figure 4 shows the evolution of each gas product during the experiments at different temperature. The H2 and CO were generated with similar profile which was short increasing in the beginning and then smoothly decreasing till end of the reaction time. The increasing of gas product was related with the excessive activity of iron ore in the catalytic process due to large surface area and no poisoning of carbon deposition. When the carbon was deposited, the activity decreased gradually. Unlike of H2 and CO, the profile of CH4 was rise and steady during reaction


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time. According to proposed mechanism of tar decomposition by Huttinger24, the tar material cracked into CH4 in first step and predominant product (reaction 12). The available of CH4 in the system together with CO2 promoted dry reforming of CH4 and produced H2 and CO. Therefore, the amount of CO2 decreased in the system while CH4 still increased due to high production from tar decomposition process. The cracking activity of tar into CH4 was steady but the production of H2 and carbon was decline during the tar decomposition experiment due to unavailability of pore within iron ore. In addition, the conversion of tar material enhanced at higher temperature which indicated by huge amount of gas production. It is well known that thermal cracking and depolymerization in the tar decomposition process are favored by an increasing of temperature. Figure 5 shows the changing on carbon content within porous ore at different reaction time and temperature. Apparently, the elevated temperature of tar decomposition produced large carbon content at anytime during the experiment due to excessive tar conversion. Generally, the process at elevated temperature would supplies more energy for break the chemical bonding through thermal cracking process.25 Hence, the gas production and carbon deposition had similar tendency which large tar decomposition at elevated temperature resulted high product both gas and carbon. Generally, the changing of carbon deposition during reaction time exhibited similar profile which rising rapidly at first 10 min and then slightly increasing till end of the experiments. The rapid rising of carbon content was caused strongly by high accessible of pores within iron ore. Furthermore, the rate of carbon deposition was decline significantly as small number of pores was available. Thus, the carbon deposition in the starting reaction time was absolutely important to control and construct dense deposition in the depth position so that the pore was still available for next deposition process. This phenomenon agreed with the gas product results as shown in the Figure 4. In the end of experiment, the carbon content was near to


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constant due to saturated condition and unavailability of pores for deposition process. Beside carbon deposition, unavailability of pore within iron ore caused catalyst deactivation as represented by gas production profile. Figure 6 shows the changing of ore phase and compound based on the XRD pattern at each experimental step. As stated in previous results that the dehydration process was removed combined water (CW) completely by producing porous Fe2O3 from FeOOH.26 The indirect reduction occurred simultaneously with decomposition process to product Fe3O4 through the reaction (13-14).

3Fe 2 O 3 (s) + CO(g) ↔ 2Fe 3 O 4 (s) + CO 2 (g)

(13)

3Fe 2 O 3 (s) + H 2 (g) ↔ 2Fe 3 O 4 (s) + H 2 O(g)

(14)

However, the compound of iron ore was never changed to FeO/Fe at longer reaction time. As well known that the indirect reduction reaction is highly depend on the ratio of H2/(H2O+H2) and CO/(CO2+CO) at specific temperature. When the ratio was quite low, the reduction never proceeds to FeO/Fe as our experiment. In the previous report, the tar decomposition at higher temperature generates more H2 and CO, thus the reduction degree of iron ore would precede more and produce FeO/Fe.16 Therefore, the thermodynamic limitation caused the ore reduction reaction never proceed to FeO/Fe in the decomposition process.

4.2 The analysis of kinetic parameters In order to calculate the kinetic parameter using equation (11), the gases conversion and selectivity were tabulated in Table 3. The gas selectivity was evaluated as mass ratio of total gas product and total product (gas and carbon). As the gas conversion was calculated based on the mass ratio of total gas product and raw material of tar. Based on the equation (11) and Table 3, the constant of reaction kinetic and catalytic deactivation were determined by linear correlation


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as shown in the Figure 7. The data correlation owned linear tendency which confirmed the valid assumptions in the development the kinetic model. Using the slope (A) and intercept (B) of linearization, the reaction rate constant and deactivation factor were determined using the equations (15).

k=

exp( A)

τ

and λ = − B

(15)

The result of reaction rate constants and deactivation factors at different temperatures were presented in Table 4. The result matched with general theoretical and previous explanation that the tar conversion and carbon deposition were increased at elevated temperature. Based on the Arrhenius equation, the activation energy (Ea) of the tar decomposition over iron ore was calculated using the data of reaction rate constant at different temperature. Table 5 shows the result of the activation energy and compared to other related experiments over various solid catalyst. It seems that the value of this experiment was comparable with other researcher even owned different raw material of tar composition. In general, it well known that tar material consisted with hydrocarbon in various form such as toluene, xylene, benzene, naphthalene, phenanthrene, antrecena, aliphatic compounds and etc. Thus, the porous iron ore was promising catalyst in the tar decomposition process with other benefits compared to conventional catalyst such as cheap, abundant natural resource and unnecessary catalyst support. In addition, the carbon deposition was no problem in this catalyst and would be advantage in the future utilization as raw material in ironmaking industry. Figure 8 shows the relationship between amount of carbon deposition and deactivation factor at various experiment temperature. Clearly, the both parameters showed similar tendency that larger carbon deposition resulted higher deactivation factor. It means that the carbon deposition within pores ore highly affected the decreasing of catalyst activity in the tar


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decomposition process. However, the high carbon content within this inactive ore catalyst would offer extra benefit in the steel production by exhibiting of high reactivity in reduction process.

5. Conclusions The proposed system which consisted of tar decomposition over over porous iron ore was promising candidate for tar reduction and offered also solution for problem related with resources, energy and environment in ironmaking industry. The kinetic analysis and deactivation of ore catalyst was evaluated in detail using proposed model to understand fully related with the system. The main findings of this study can be summarized as follows 1. The generation of both H2 and CO gasses had similar profile which was short rising and then declining smoothly till the end of experiment. In the starting experiment, the catalyst iron ore owned high activity in tar decomposition due to large surface area and no poisoning of carbon deposition. Beside decompsoition process, the indirect reduction occured simultaneaously to produce Fe3O4. However, thermodynamic limitation caused the ore reduction never proceed to FeO/Fe. 2. The reaction rate constant, k and deactivation factor, λ were calculated successfully using the proposed model with the range of 0.13 – 0.55 s-1 and 1.72 – 2.53 s-1, respectively at 500-700oC. Based on the Arrhenious plot, the activation energy, Ea was around 44.86 kJ/mol. It seems that the kinetic parameters of this experiment were comparable with other researchers. 3. Obiously, the deactivation factor exhibited similar tendency with amount of carbon deposition within pores iron ore. It means that the carbon depsoition highly affected to the catalyts deactivation during the tar decompistion process. The carbon deposition


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raised rapidly at the beginning process due to high accessible in pores within iron ore. Furthermore, the rate of carbon depsoition diminished significantly due to small number of pore available. These results represent the important data and knowledge related with the proposed system of tar decomposition over natural and cheap calaytst of porous iron ore.


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FIGURE CAPTIONS Figure 1 Schematic diagram of continuous fixed bed reactor which used for development of kinetic equation model. Figure 2 Experimental apparatus for tar decomposition over porous ore. Figure 3 Comparison of tar decomposition product for both raw materials: toluene and mixed liquid tar-toluene. Figure 4 The evolution of gas formation during the experiments at various temperatures. Figure 5 Effect of temperature on carbon content within porous ore as a result of tar decomposition process. Figure 6 Changing of XRD patterns of porous iron ore at each experiment steps Figure 7 Determination of kinetic parameters using linearization method at different experiment temperatures. Figure 8 The relationship between deposited carbon and deactivation factor at different temperature

TABLES Table 1 Elemental analysis and major components in the lignite coal tar as raw material Elemental analysis Elemental

%mass

Major component Component

%mol

Carbon

88.59

Benzene

20.97

Hydrogen

8.56

Naphthalene

12.95

Oxygen

2.16

Phenanthrene

4.71

Nitrogen

0.53

Toluene

4.44

Sulfur

0.16

Anthracene

1.99

Acenaphthylene

1.98


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 28

Table 2 The main properties of pisolite iron ore. TFe1 [%mass] Pisolite ore 1

FeO [%mass]

49.73

0.12

C [%mass]

CW2 [%mass]

Surfaces area [m2/g]

0.14

5.90

11.83

TFe: total iron, 2CW: combined water

Table 3 The product, gas conversion and selectivity of each experiment condition Product [mg]

Time Gas

[min]

o

o

Selectivity [-] Carbon

o

o

o

Conversion [-]

Gas o

o

o

Gas o

o

600oC

700oC

500 C

600 C

700 C

500 C

600 C

700 C

500 C

600 C

700 C

500 C

10

1.22

3.54

5.42

11.65

12.37

16.67

0.095

0.223

0.245

0.054 0.016 0.238

20

2.36

5.34

9.09

12.92

14.42

18.30

0.154

0.270

0.332

0.052 0.012 0.199

30

2.84

6.19

11.39

14.17

16.82

22.43

0.167

0.269

0.337

0.042 0.091 0.166

40

3.20

6.85

13.48

15.05

16.75

20.40

0.175

0.290

0.398

0.035 0.075 0.148

Table 4 The apparent constant of reaction rate and catalyst deactivation factor on tar decomposition over porous ore Temp. [oC]

Reaction rate constant, k [s-1]

Deactivation factor, λ [s-1]

500

0.13

1.72

600

0.19

1.79

700

0.55

2.53

Table 5 Activation energy of tar decomposition reaction over porous ore and other catalyst Catalyst

Activation energy, Ea [kJ/mol]

Raw material

Ref.

Porous ore

44.80

Coal tar (5%) + toluene

This study

Dolomite

67.41

Coal tar + pyrolysis gas

[27]

Zeolite

37.20

Simulated tar (1-MN)

[9]

CaO

32.90

Gasco coal tar

[23]


Page 21 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

Energy & Fuels

Qi, z

L

∆Z

Qi, z+∆z D

Fig.1. Schematic diagram of a fixed bed reactor which is used for the development of kinetic equation model.


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

Page 22 of 28

Constant pump Mass flow controller

Infrared furnace Quartz reactor

Quartz wool

Tar + toluene

Porous ore Micro GC

N2 gas

Temperature controller

Atmosphere Cold trap (-73oC)

Fig.2. Experimental apparatus for tar decomposition over porous ore.


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Carbon deposition within ore at 40 min [%mass]

0.8

Flowrate [cm3/min (STP)]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

Energy & Fuels

A : Toluene (only)

B : Toluene and Liquid tar (19:1)

0.6

H2 CH4 CO CO2

6.7 %

4.9 % 0.4 Run A

0.2

C

Run B

0 5

10

15 20 25 30 Reaction time [min]

35

40 5

10

15 20 25 30 Reaction time [min]

35

Fig.3. Comparison of tar decomposition product for both raw materials: toluene and mixed liquid tar-toluene.


40

Energy & Fuels

1

0.1

Flow rate [cm3/min (STP)]

LIGN tar 0.8

0.08

0.6

Fig.4. The evolution of gas formation during the experiments at various temperatures.

700oC

H2

700oC

CO

0.06 600oC

0.4

0.04 600oC

0.2

0.02 500oC

500oC 0 0.15

0 0.5

0.12 700oC

CH4

0.09 0.06 600oC

0.03



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0.4 700oC

CO2

0.3 0.2 600oC 0.1

500oC

500oC 0

0 0

10 20 30 Reaction time [min]

40

0

10 20 30 Reaction time [min]


40

Page 25 of 28

Energy & Fuels

10 LIGN Tar 700oC

Carbon content [%mass]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

8

600oC 6 500oC 4

2

Experiment Calculation(polynomial: 3rd order)

0 0

10

20 30 Reaction time [min]

40

Fig.5. Effect of temperature on carbon content within porous ore as a result of tar decomposition process.


Energy & Fuels

LIGN-600oC

FeOOH

Fe2O3

c

Fe3O4 Original ore

c c

Diffraction internsity [a.u]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

Page 26 of 28

c

c

c

c

c

Dehydrated ore Carbonized ore at 5 min 10 min 20 min 30 min

40 min

20

30

40

50

60

70

80

90

2θ [degree, Cu-Kα] Fig.6. Changing of XRD patterns of porous iron ore at each experiment steps.


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2

LIGN Tar

500oC 600oC

1

yGS ln ln 1 fGS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

Energy & Fuels

700oC

0 R2: 0.88 R2: 0.95

-1

R2: 0.94

Linearization

-2 0.25

0.50

0.75 

1.00

t tR

Fig.7. Determination of kinetic parameters using linearization method at different experiment temperatures.


Energy & Fuels

4 LIGN Tar Time : 40 min Catalyst weight : 250 mg

8

3

6

2

4

1 400

500

600 700 Temperature [oC]

Deactivation factor [s-1]

10

Deposited Depositedcarbon carbon[%mass] [%wt]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

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800

Fig.8. The relationship between deposited carbon and deactivation factor at different temperature


Tar Decomposition over a Porous Iron Ore Catalyst: Experiment and

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