Effects of Natural Dolomite Catalysts on Cracking Anthracene Oil

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Effects of Natural Dolomite Catalysts on Cracking Anthracene Oil Peng Liang, Juan Yu, Yaqing Zhang, Tiantian Jiao, and Xizhuang Qin Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b02017 • Publication Date (Web): 13 Oct 2017 Downloaded from http://pubs.acs.org on October 14, 2017

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Effects of Natural Dolomite Catalysts on Cracking Anthracene Oil Peng Liang*, Juan Yu, Yaqing Zhang, Tiantian Jiao, and Xizhuang Qin College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao, Shandong 266590, P. R. China Abstract Natural dolomite catalysts, representing a cheap and environmentally friendly alternative to nickel-based compounds, can be utilized for the cracking of anthracene oil to form more valuable products. The impact of operating conditions (temperature, water/oil mass ratio, and space velocity) on the distribution and yield of pyrolysis products was investigated in a fixed-bed reactor, providing insights into the mechanism of cracking. The gaseous products were analyzed by gas chromatography, the catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy, and the pyrolysis oil was analyzed by gas chromatography–mass spectrometry. The obtained results revealed that the gaseous products comprised H2, CO, CO2, CH4, and C2+. Compared to anthracene oil, the pyrolysis oil contained significantly decreased amounts of alkyl aromatic hydrocarbons and indene compounds, as well as an increased content of polycyclic aromatic hydrocarbons such as naphthalene and phenanthrene. XRD and SEM analyses revealed granular coke deposition on the catalyst surface at high temperature accompanied by partial conversion of the catalyst to CaCO3, which could be mitigated by utilizing high water/oil ratios. Thus, this study demonstrated the influence of reaction conditions on natural-dolomite-catalyzed cracking of anthracene oil, which is important for optimizing industrial production processes. Keywords: anthracene oil; natural dolomite catalysts; catalytic cracking; coke deposition

1. Introduction The rapidly developing coal chemical industry of China has achieved comprehensive coal utilization, relying on coal pyrolysis as a common coal processing technology. Although this process converts coal into more valuable gaseous, liquid, and solid products, improving its utilization efficiency, the heavy tar components of the pyrolysis 1

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gas inevitably mix with dust and other substances to afford tar residue that can block pipes, corrode equipment, and pose system security risks.1–3 Therefore, the key goal of coal pyrolysis optimization is the realization of effective tar cleaning, with catalytic cracking considered one of the most cost-effective and promising tar processing methods. Moreover, stream catalytic cracking can be promoted by improving the water/material ratio,4 and the calorific value of pyrolysis gas can be increased by converting hydrogen and oxygen contained in the stream into H2, CH4, and CO.5 Tar decomposition is commonly facilitated by the addition of catalysts, such as recently popularized synthetic nickel-based6–8 and natural dolomite catalysts,9–11 the activity of which can be improved by certain additives (e.g., Ce,12 Mo,13 and La14). Unfortunately, the above catalysts are easily deactivated by carbon deposition, active metal component sintering, and sulfur poisoning. Sato et al.15 reported that although the resistance of nickel-based catalysts to sulfur poisoning can be enhanced by modification with WO3, they are nonetheless inactivated by carbon deposition and sintering. This behavior is detrimental to industrial production processes because the regeneration of deactivated catalysts not only increases operating costs but also complicates system operation, with discarded catalysts also being potential pollutants owing to the release of heavy metal ions.16 A number of reports indicate that the fused aromatics present in tar have relatively electronegative π-electron clouds, whereas metal oxides exhibit a certain polar-activated performance. Thus, π-electron clouds should be destabilized in the presence of metal oxides, resulting in facile bond cleavage.17–18 Natural dolomite catalysts represent one example of such oxides (CaO and MgO) that facilitate tar cracking, and modification of these catalysts using highly active additives allows cracking to be performed without catalyst regeneration. Some previous studies on biomass gasification have reported the benefits of dolomite catalysts for tar decomposition. Narváez et al.19 reported that the tar content decreased from 10 to 4 g/Nm3 with calcined dolomite (3 wt.% mixed 2


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with biomass). Delgado et al.20 also observed that the tar content decreased to 50% when dolomite catalysts were used as the bed material. Further, dolomite catalysts do not suffer from the abovementioned problems of nickel-based catalysts and are additionally capable of adsorbing H2S and HCl from coal gas.21 Finally, inactivated dolomite catalysts do not require costly recycling and regeneration procedures. Sun et al.22 found that Fe-modified dolomite featured good mechanical strength and achieved high tar conversion, and Liang et al.23 compared Ni-modified dolomite with natural dolomite, showing that the former exhibited superior water vapor adsorption, dissociation capacity, and stability. Recent research on modified dolomite catalysts has mainly focused on model compounds such as benzene, naphthalene, and toluene. However, tar has an extremely complex composition, comprising over 1000 individual aromatic compounds together with oxygenated hydrocarbons and complex aromatics,24–25 which raises the question of whether the existing model compounds can well represent the interactions between tar components. Tar can be divided into six fractions according to their distillation points, namely light oil (280 °C), and asphalt. Anthracene oil represents the heavy tar components, which mainly have 2–4 aromatic rings, such as phenanthrene, anthracene, fluoranthene, and pyrene.26 Some studies have examined anthracene as a model compound for producing high-quality liquid fuels. Fan et al.27 found that hydrocracking of anthracene catalyzed by NiFe/HZSM-5 produced ethyl biphenyl, which indicates the occurrence of high-efficiency hydrocracking of the central ring of anthracene. Other studies have reported that the addition of water can reduce coke formation28 and even increase liquid-phase yields by extracting light oils29 during the hydroprocessing of heavy oils. Herein, as a systematic extension of previous studies, we investigated the effect of natural dolomite catalysts on anthracene oil cracking, focusing on the influence of temperature, space velocity, and water/oil ratio, and characterized the 3


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gaseous, liquid, and solid phases to provide important insights into the tar cracking mechanism. 2. Experimental 2.1 Materials. Natural dolomites (Shijiazhuang, Hebei province, China) were sequentially calcined in a muffle furnace at 450 °C (2 h) and 900 °C (5 h), and subsequently sieved to a diameter of 0.42–0.84 mm. Anthracene oil was sourced from the Shanxi coking plant. 2.2 Equipment and procedures. Catalytic tar reforming was carried out in a fixed-bed reactor (Figure 1), comprising two peristaltic pumps, a preheater, an inner reactor (internal diameter = 20 mm, overall length = 1000 mm), an ice-cooled condenser, and other parts. Water and raw oil were injected into the preheater using the peristaltic pumps at feeding rates of 0.062 and 0.064 g/min, respectively. The preheater temperature was set at 260 °C to facilitate the evaporation of liquid reactants. Dolomite catalyst samples (10 g) were loaded into the middle of the fixed-bed reactor and heated to a predetermined temperature under nitrogen. During the cracking process, the feeding rates of H2 and N2 were 20 and 40 mL/min, respectively, and space velocity was adjusted by modifying the N2 feeding rate in each run. After each reaction, the pyrolysis gases were separated by ice-water condensation, and the noncondensable gases and condensable oil were collected for gas chromatography (GC) analysis and gas chromatography–mass spectrometry (GC-MS) analysis, respectively. The gas, solid, and oil yields were calculated as follows: gas yi el d (%): Y G

=

∑m ×t ,

(1 )

solid yield (%): Y S =

ms × 100% , moil0

(2)

oil yi eld (%): Y O =

moil f moil0

i

moil0

× 100% ,

(3 )

4


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gas hourly space velocity (h –1 ): V =

(Voil + V water + V N2 + V H 2 ) × 60 , Vcatalysts

(4)

where mi , ms , moil f , moil0 , and t denote the mass flow rate of pyrolysis gas component i (g/min), the mass increase of the dolomite catalyst after cracking (g), the quantity of cracked oil (g), the quantity of raw oil (g), and the reaction time (min), respectively. Voil , V water , V N2 , and V H 2 correspond to the volume feed rate (mL/min) of raw oil, water, N2, and H2, respectively, and Vcatalysts denotes the volume (mL) of the 10 g dolomite catalyst sample. All experiments were performed in triplicate, with the results reported as average values, and the mass balance before and after pyrolysis exceeded 95%. 2.3 Product analysis and characterization. Gaseous products were analyzed by GC. Small-molecule gases such as H2, N2, CO, CH4, and CO2 were analyzed using a thermal conductivity detector (GC-TCD; Ruihong, SP-6800A, China), whereas a flame ionization detector (GC-FID; Fuli, SP-6890, China) was used to analyze gaseous hydrocarbons such as CH4, C2H6, C2H4, C3H8, C3H6, and C4+. The molar amounts of gaseous products produced by per gram of anthracene oil were calculated based on the content of CH4. The moisture content of the liquid products was determined using the GB/T 2288-2008 method to calculate the yield of cracked oil, which was analyzed by GC-MS (Agilent, 7890A/5975C, USA). The chromatograph was equipped with an HP-5MS capillary column (30 m × 250 µm × 0.25 µm), and helium was used as a carrier gas at an injection rate of 1 mL/min. The sample (0.2 µL) was injected in splitless mode. The column oven temperature was set at 300 °C, with heating performed from 60 to 300 °C at a rate of 5 °C/min. Mass spectra were recorded in electron ionization mode at 70 eV for m/z = 35–300. The compositions of the dolomite catalysts were determined by X-ray diffraction (XRD; Rigaku, D/max-2550, Japan) using Cu Kα radiation. The XRD patterns were recorded at 200 mA and 40 kV for 2θ =

5


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20–90° at a scan rate of 5°/min. The surface morphologies of the catalysts were observed by scanning electron microscopy (SEM; Zeiss, EVO MA 10/LS 10, Germany) operated at an accelerating voltage of 10 kV and transmission electron microscopy (TEM; FEI, Tecnai G2 F20, USA) operated at 200 kV. 3. Results and discussion 3.1 Catalyst characterization. The XRD patterns of catalysts before and after cracking shown in Figure 2 reveal that the calcined catalysts exhibited CaO diffraction peaks at 2θ = 32.2, 37.6, 53.8, and 62.3°, as well as MgO diffraction peaks at 2θ = 42.92 and 67.4°. After 5 h at 700 °C, the intensity of the CaO and MgO peaks decreased, indicating that the catalyst was not inactivated, and a further decrease was observed at 800 °C. However, the observation of a CaCO3 peak at 2θ = 29.8° indicated that these catalysts were partially deactivated at high temperatures. Figure 3 shows SEM images (3000× magnification) of catalysts subjected to different experimental conditions. The surface of the fresh dolomite catalyst was relatively coarse and porous, featuring evenly distributed pores (Figure 3a). In contrast, the catalyst surface became smoother and the size of the honeycomb-like features decreased after operation for 5 h (Figure 3b), indicating that the catalyst surface was covered by coke produced during pyrolysis. A comparison of Figures 3b and 3c shows that the honeycomb shape was more pronounced in the latter case, corresponding to a smaller amount of carbon deposited on the catalyst surface, which suggests that the reaction of carbon with water vapor ultimately hinders coke deposition. A comparison of Figures 3b and 3d reveals the presence of granular material on the catalyst surface in the latter case, which probably reflects the accumulation of coke generated by high-temperature catalytic tar cracking.30 Furthermore, the TEM images of the spent catalyst in Figure 4 clearly show the deposition of coke in the partial honeycomb structure, observed as black materials in the images, resulting in a smoother catalyst surface. To verify the above 6


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results, three types of dolomite catalysts were sequentially calcined at 900 °C (2 h) in nitrogen and at 900 °C (2 h) in air in a fixed-bed furnace. Calcination of catalysts b, c, and d in air resulted in mass decreases of 19.83, 19.26, and 31.28%, indicating that high temperatures can facilitate carbon deposition. 3.2 Effects of operation conditions on dolomite-catalyzed cracking of anthracene oil. Figure 5 shows the effect of temperature on the pyrolysis of anthracene oil at a constant space velocity (300 h–1) and water/oil mass ratio (2.0:1). Figure 5a reveals that increasing the reaction temperature increased the yield of gas and decreased that of oil, indicating that higher temperatures not only enhance the extent of the cracking reaction but also facilitate the polymerization of anthracene oil.31 Moreover, reaction temperatures above 750 °C resulted in significantly larger gas yields (29–60%), whereas those of solid products remained unchanged. The increased generation of H2, CO, and CO2 (Figure 5b) indicated that both coke on the catalyst surface and some of the cracking products reacted with water at high temperatures,32–33 facilitating the generation of gaseous products. Figure 6 shows GC-MS chromatograms of the cracked oil obtained at different temperatures and a constant space velocity (300 h–1) and water/oil ratio (2.0:1). The main constituents of anthracene oil corresponded to alkyl aromatics, such as benzene, 1-methyl-4(phenylethyl)-, as well as tricyclic and polycyclic aromatic hydrocarbons (PAHs). Figures 6b–6f show that the GC-MS peak positions did not significantly change after cracking. Changes of reaction conditions altered the relative contents of individual components, as manifested by changes in peak width and abundance. Table 1 shows that the oil components can be divided into nine classes, i.e., alkyl aromatics, indene compounds, double-ring alkyl aromatics, biphenyl, oxygenated compounds, sulfur-containing compounds, naphthalene and its homologues, fluorene and its homologues, and tricyclic and larger PAHs. The contents of alkyl aromatics and indene compounds significantly decreased after cracking owing to high-temperature dealkylation.34–35 Moreover, the formation of gaseous hydrocarbons such as CH4 confirmed that alkyl aromatic 7


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side chains and benzene rings underwent C–C bond cleavage during cracking,36 as reported previously,37–38 which reveals that compounds containing aliphatic hydrogens (by dealkylation), acenaphthylene (on account of the double bond in the molecule), and naphthalene (less active than anthracene) broke down most vigorously in anthracene oil. The content of indene compounds was also reduced after cracking, which was ascribed to ring-opening reactions.39 The phenyl fragments produced by cracking condensed into biphenyl, terphenyl, and PAHs, resulting in an increased content of fused aromatic hydrocarbons. The increased contents of biphenyl and terphenyl indicated their role as intermediate compounds in the polymerization pathway.40 High temperatures are known to promote the polymerization of PAHs when sand is used as a bed material.41 Notably, dolomite as a bed material under the same temperature conditions lowered the tar content in the flue gas. Anthracene oil, which belongs to the heavy tar component, is difficult to undergo open-loop reaction with natural dolomite, resulting in anthracene oil after cracking became a little heavier at relatively high temperatures in this study. Oxygenated compounds found in raw oil mainly corresponded to furan and dibenzofuran derivatives, which are relatively stable and only undergo hydrodeoxygenation in the presence of highly active catalysts.42 Similarly, the main sulfur-containing component corresponded to dibenzothiophene, which has a complex structure and highly aromatic nature that complicates hydrodesulfurization under normal pressure.43–44 Therefore, the content of oxygenated and sulfur-containing compounds increased after cracking. Figure 7 shows the effect of the water/oil ratio on the pyrolysis of anthracene oil at a constant space velocity (300 h–1) and temperature (700 °C). The yield of gaseous products increased with increasing water/oil ratio, in contrast to the yield of cracked oil and the extent of carbon deposition (Figure 7a). This phenomenon is different from that reported previously,27 where water increased the liquid yield and reduce the gaseous yield during hydrocracking of Daqing residue oil. In this study, increasing the water/oil ratio had a limited effect on the 8


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catalytic cracking of tar, although this ratio significantly affected the deposition of coke on the calcined catalysts. As illustrated in Figure 7b, the generation of H2 and CO2 was directly responsible for the increase in overall gas production, reflecting the occurrence of the water gas reaction (H2O + C ↔ CO + H2) and the water gas shift reaction (CO + H2O ↔ CO2 + H2).45 Figure 8 shows GC-MS chromatograms of oil cracked at different water/oil ratios, a space velocity of 300 h–1, and a temperature of 700 °C. The content of single-ring alkyl aromatic hydrocarbons was significantly reduced at increasing water/oil ratios, illustrating that water is more likely to dissociate and adsorb on the catalyst surface when present at high stream levels. Therefore, water induces the hydroxylation of catalysts to promote hydrocarbon pyrolysis.46 Table 2 shows that no single-ring alkyl aromatic hydrocarbons were detected at a water/oil ratio of 2.5:1, probably owing to the mass loss of alkylbenzenes during oil–water separation. The contents of the other compounds in the pyrolysis oil were barely affected by the increasing water/oil ratio, indicating that this parameter had little influence on anthracene oil cracking. Figure 9 shows the effect of space velocity on the pyrolysis of anthracene oil under constant experimental conditions (water/oil ratio = 2.0:1, temperature = 700 °C). The gas and oil yields decreased and increased, respectively, with increasing space velocity, with H2 generation decreasing from 8.2 to 3.0 mmol/g. These results indicated that increasing the space velocity indirectly increased the feed flow rate, which reduced the encounter probability of reactants and active catalyst centers, and thus decreased the reaction time/extent and the possibility of carbon deposition. Figure 10 shows GC-MS chromatograms of oil cracked at different space velocities, a temperature of 700 °C, and a water/oil ratio of 2.0:1. The obtained compositions (Table 3) were similar to those shown in Tables 1 and 2, exhibiting only moderate changes at space velocities above 600 h–1, with the amount of fused aromatic 9


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hydrocarbons slightly increasing. On the other hand, the content of sulfur-containing and oxygenated compounds slightly decreased, demonstrating that these species with simple structures were not readily converted to polyaromatic compounds under these conditions. Thus, although the conversion of anthracene oil can be increased by decreasing the space velocity, this approach requires larger amounts of catalysts and increases the operating cost per given amount of raw oil. 4. Conclusion Herein, we investigated the catalytic cracking of anthracene oil over natural dolomite catalysts in a fixed-bed reactor, showing that increased temperatures and water/oil ratios improved the yields of gaseous pyrolysis products, particularly those of H2, CO, and CO2. In addition, the deposition of coke on the catalyst surface was reduced by increasing the water/oil ratio. During cracking, alkyl aromatics and indene compounds probably underwent dealkylation and ring-opening reactions, respectively, with the thus-produced fragments condensing with free radicals to form larger fused aromatic hydrocarbons. Overall, the amounts of alkyl aromatic hydrocarbons and indene compounds in the pyrolysis oil were significantly decreased in the presence of dolomite catalysts, whereas the amounts of PAHs (naphthalene, phenanthrene, etc.) were increased.

Author information Corresponding author *Tel.: +86 13678890728; fax: +86 532 86057718; e-mail: [email protected]. ORCID: Peng Liang, 0000-0003-2808-865X. Notes The authors declare no competing financial interest.

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Acknowledgment The authors are grateful to the National Science Foundation of China (Grant No. 21376142) for financial support.

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Table 1.

Before reaction

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GC-MS analysis of oil under different temperature conditions. After reaction of different temperature conditions(300h-1 space velocity, 2.0:1water/oil ratio)

Component（ %） Raw oil

650°C

700°C

750°C

800°C

850°C

Alkyl-substituted aromatics

6.47

0.91

0.69

0.65

1.57

2.55

Indene compounds

2.57

0.21

0.17

0.20

/

0.42

Double-ring alkyl aromatics

33.43

4.94

3.17

1.95

6.09

6.69

Biphenyl

/

2.12

2.12

1.57

2.44

2.58

Oxygenated compounds

2.89

5.78

4.67

5.43

6.04

5.95

Sulfur-containing compounds

1.40

3.67

5.11

5.13

4.50

4.58

Naphthalene and it homologue

3.97

5.88

6.42

5.18

6.72

7.07

Fluorene and it homologue

4.00

4.67

4.67

4.89

4.49

3.93

Tricyclic and larger PAHs

46.26

62.58

63.10

60.79

60.22

59.31

14


Page 15 of 26

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

Energy & Fuels

Table 2.

GC-MS analysis of oil from different water/oil ratio conditions.

Before reaction

After reaction of different water/oil ratio conditions(300 h-1space velocity, 700 °C temperature)

Component（ %） Raw oil

1.5:1

2.0:1

2.5:1


6.47

3.33

0.69

/

Indene compounds

2.57

0.43

0.17

/


33.43

7.00

3.17

0.16

Biphenyl

/

2.23

2.12

1.57

Oxygenated chemical

2.89

5.11

4.67

5.73

Sulfur-containing compound

1.40

4.55

5.11

1.12


3.97

6.20

6.42

5.92


4.00

5.75

4.67

5.38


46.26

55.71

63.10

67.75

15


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

Table 3.

Page 16 of 26

GC-MS analysis of the oil produced under different space velocity conditions.

Before reaction

After reaction under different space velocity conditions (2.0:1 water/oil ratio, 700°C temperature)

Component（%） Raw oil

300h-1

600 h-1

900 h-1

1200 h-1


6.47

0.69

2.20

2.24

2.02

Indene

2.57

0.17

0.38

0.35

0.36


33.43

3.17

4.25

4.50

3.47

Biphenyl

/

2.12

1.94

1.82

1.57

Oxygenated chemical

2.89

4.67

4.06

3.94

3.31

Sulfur-containing compound

1.40

5.11

4.69

4.72

4.51


3.97

6.42

5.17

4.88

4.59


4.00

4.67

5.66

5.43

4.91


46.26

63.10

62.76

62.44

64.75

16


Page 17 of 26

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

Energy & Fuels

1: water; 2: raw oil; 3,4: metering pump; 5: hydrogen; 6: nitrogen; 7: preheater furnace; 8: preheater; 9: reactor; 10: dolomite catalysts;

11: reactor furnace; 12: condenser; 13: ice-water mixtures

Figure 1.

Schematic diagram of the fixed-bed reaction equipment.

17


Energy & Fuels

2000

★

★CaO ◆MgO ▽CaCO 3

◆ 1600

★

★

▽

◆

★

c

★

b

★

a

★ Intensity

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 18 of 26

1200

◆

★ 800

★ ◆

★

400

★

◆

★

◆

0 20

30

40

50

60

70

80

90

2θ(deg) a: fresh catalyst; b: 700 °C,mH2O/moil = 2.0:1,space velocity = 300 h-1; c: 800 °C,mH2O/moil= 2.0:1,space velocity = 300 h-1 Figure 2.

XRD patterns of catalysts before and after reaction.

18


Page 19 of 26

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

Energy & Fuels

a: fresh catalyst; b: 700 °C,mH2O/moil = 2.0:1; c: 700 °C,mH2O/moil = 2.5:1; d: 800 °C,mH2O/moil = 2.0:1 Figure 3.

SEM images of catalysts under different conditions.

19


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

Figure 4.

Page 20 of 26

TEM images of catalyst under condition with 800 °C, mH2O/moil = 2.0:1, space velocity = 300 h-1.

20


Page 21 of 26

100

a cracked oil

H2

solid

Gas generation (mmol/g)

gas 80

Yield (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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

60

30 20

CH4

CO2

C2

+

b

30

20

8 6 4

10

2 0

0 650

700

750

800

850

650

Temperature (°C) Figure 5.

CO

700

750

800

850

Temperature (°C)

Effect of temperature on the distribution of anthracene oil cracking products (300h-1 space velocity, 2.0:1water/oil ratio)

21


Energy & Fuels

30

a

Abundance

3

b

6

T=650°C 7

15

8

4

10

6

10

7

5

8

2

5

5

2

10 3 4

9

1

11

12

13

0

0

c

20

Abundance

20

Raw oil

20

1

6

7

T=700°C

20

d

6

T=750°C 7

15

15

8

8

10

10

5

10 3 4

2

5 11

9

1

5

13

12

2

10 34

9

1

0

5

11

13

12

0

e Abundance

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 22 of 26

6

20

T=800°C

15 8

10 5

2 10

9

1

5 34

11

8

10

12

2

5

13

10

9

1

3 5 4

11

12

13

0

0 5

T=850°C 7

7

15

f

6

20

10

15

20

25

30

35

40

5

10

Time (min)

15

20

25

Time (min)

30

35

40

1: homologues of benzene; 2: naphthalene; 3,4 : benzene, 1-methyl-4(phenylethyl)-; 5: fluorine; 6 :phenanthrene; 7: fluoranthene;

8: pyrene; 9: 1-methyl naphthalene; 10: biphenyl; 11: dibenzothiophene; 12: 2-phenyl naphthalene; 13: triphenylene

Figure 6.

GC-MS chromatograms of the cracked tar at different temperatures (300h-1 space velocity, 2.0:1water/oil ratio).

22


Page 23 of 26

10

100

gas

cracked oil

solid

a

H2


90

Yield (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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

80 70 20 15

CO

CH4

CO2

+ C2

b

5

3 2

10 1 5 0

0

1.0:1

Figure 7.

1.5:1 2.0:1 mH2O / mtar

2.5:1

1.0:1

1.5:1 2.0:1 mH2O / mtar

2.5:1

Effect of water/oil ratio on distribution of anthracene oil cracking products (300 h-1space velocity, 700 °C temperature).

23


Energy & Fuels

30

b

a Raw oil

Abundance

20

mH2O/mtar=1.5:1

15

7

6

3 20

4 10

6

10

8

7 5

8 1

3 5 10 4

2

5

2

1

11

12

9

13

0

0

c 20

mH2O/mtar=2.0:1

6

Abundance

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 24 of 26

6

d mH2O/mtar=2.5:1

20

7

7

15

15

8

8 10

10

5

34

2

5

5

10

11

9

1

5

13

12

14

2

9

10

3

11

13

12

0

0

5

10

15

20

25

30

35

40

5

10

Time (min)

15

20

25

30

35

40

Time (min)

1: homologues of benzene; 2: naphthalene; 3,4: benzene, 1-methyl-4(phenylethyl)-; 5: fluorine; 6: phenanthrene; 7: fluoranthene;

8: pyrene; 9: 1-methyl naphthalene; 10: biphenyl; 11: dibenzothiophene; 12: 2-phenyl naphthalene; 13: triphenylene; 14: 2-ethyl hexanol

Figure 8.

GC-MS chromatograms of the oil acquired under different water/oil ratio conditions (300 h-1space velocity, 700 °C temperature).

24


Page 25 of 26

100

cracked oil

solid

10

a

H2


gas Yield (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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

80

25 20

CO2

C2

+

b

6 4

0.8 0.6

10

0.4

5

0.2 0.0 300

600

900

-1

1200

300

Space velocity (h ) Figure 9.

CH4

8

15

0

CO

600

900

-1

1200

Space velocity (h )

Effect of space velocity on the distribution of anthracene oil cracking products (2.0:1 water/oil ratio, 700°C temperature).

25


Energy & Fuels

30

a

b

20

Raw oil

-1

Abundance

V=300h

6

3

20

7

15

4

8

10

6

10

7

5

8 1

5

2

5

2

10

34

11

9

1

0

0

13

12

c

20

d

20

-1

V=600h

-1

15

15

7

10 5 10 3 4

2

5

8

5

5 11

13

12

2

9

1

0

7

10

8

5

1

0 10

15

20

25

V=900h

6

6

Abundance

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 26 of 26

30

35

40

5

10

Time (min)

10

9

15

34

20

11

25

Time (min)

12

13

30

35

40

1: homologues of benzene; 2: naphthalene; 3,4: benzene, 1-methyl-4(phenylethyl)-; 5: fluorine; 6: phenanthrene; 7: fluoranthene; 8: pyrene;

9: 1-methyl naphthalene; 10: biphenyl; 11: dibenzothiophene; 12: 2-phenyl naphthalene; 13: triphenylene

Figure 10.

GC-MS chromatograms of the oil produced under different space velocity conditions (2.0:1 water/oil ratio, 700°C temperature).

26


Effects of Natural Dolomite Catalysts on Cracking Anthracene Oil

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