Upgrading of Heavy Oil with Chemical Looping Partial Oxidation over

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Upgrading of Heavy Oil with Chemical Looping Partial Oxidation over M2+ Doped Fe2O3 Dechao Wang, Lijun Jin, Yang Li, and Haoquan Hu Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b03560 • Publication Date (Web): 11 Dec 2018 Downloaded from http://pubs.acs.org on December 15, 2018

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Upgrading of Heavy Oil with Chemical Looping Partial Oxidation over M2+ Doped Fe2O3 Dechao Wang, Lijun Jin, Yang Li, Haoquan Hu* State Key Laboratory of Fine Chemistry, Institute of Coal Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China ABSTRACT Producing light fuels from heavy oil by means of partial oxidation (POX) is a potential method. Chemical looping POX (CLPOX) process using active oxygen species from metal oxides can avoid the direct contact between hydrocarbon molecules and air. The key of CLPOX is the selection of oxygen carrier. In this study, bivalence metal oxides M2+ including Cu, Ni, Zn, Mg and Ca doped Fe2O3 were prepared, and their POX performances were evaluated at 550 oC for 1 h under atmospheric pressure by using vacuum residue (VR) as heavy oil to screen the oxygen carrier for CLPOX. The results showed that Ca doped Fe2O3 (denoted as Fe-Ca) exhibits the best POX performance with respect to the highest diesel oil yield being 39.2 wt%, and the gasoline and VGO yields are 8.5 wt% and 27.4 wt%, separately. The characterization of the oxygen carrier revealed that the improvement of POX performance is mainly associated with the largest specific surface area and high concentration of O-. The utilization of Fe-Ca as oxygen carrier showed good regenerability after 20th cycle in CLPOX. Keywords: Chemical looping, Partial oxidation, Heavy oil, Fe2O3, M2+ doping,

1. INTRODUCTION With the increase demand of light fuels and decrease reserve of conventional light crude, the conversion of heavy oil into valuable light fuels or chemicals has been received much attention1-3.

*

Corresponding author. Tel. & Fax: +86-411-84986157 E-mail: [email protected] (Haoquan Hu) 1

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Compared with conventional crude oil, heavy oil has properties of low hydrogen to carbon ratio and high content of heteroatoms such as sulfur and nitrogen1, 4. Due to the different properties of heavy oil, it is still a challenge to produce light fuels from heavy oil. Generally, heavy oil upgrading technologies can be classified into two types: decarbonization and hydrogenation5-8. Compared to traditional thermal cracking, heavy oil conversion can be achieved by means of partial oxidation (POX) 9. Generally, oxidants used in POX include O210, 11, O312, H2O13, 14, H2O215 and transition metal oxide9, 16, 17. Due to their property of changing valence state under reducing/oxidizing atmosphere, the transition metal oxide can release and store oxygen, which can be seen as oxygen carrier. It also suggests that they can be recycled in the heavy oil upgrading. The application of Fe2O3 based materials for POX of heavy oil has been reported9, 18, 19. Fumoto et al19 synthesized zirconia-supporting iron oxide and applied to the petroleum residue upgrading in a steam atmosphere. However, when the cycle of reaction and regeneration was performed, the prepared zirconia-supporting iron oxide lost its activity due to the peeling of zirconia. In our previous work, the Al and Zr co-doped Fe2O3 showed a better POX performance than pure Fe2O3 due to their large specific surface and high concentration of O- 9. The Al and Zr doped Fe2O3 also showed a stable POX performance after 6 cycles, which is mainly attributed to the replenishment of oxygen species from air. After POX reaction, crystal transition from oxidation to reduction state was detected by XRD analysis19, 20. The loss of active oxygen can be regenerated when the spent sample was calcined in air condition. This process can be referred as chemical looping (CL), which involves the reduction and oxidation of metal oxides (MOx)21, 22. The role of MOx in this process can be deemed as oxygen carrier to release and restore oxygen species between two reactions, namely reducer and oxidizer22. 2


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The CL process can also be applied to the POX process, and it could be considered as chemical looping partial oxidation (CLPOX). According to dopants valence state, Al and Zr is tri-valence and tetra-valence metal ions, respectively. Metal oxides with divalent are also potential dopants that can be used to modify the physiochemical property of Fe2O3. This in turn can alter the POX performance of Fe2O3. In this study, bivalence metal oxides MO including CuO, NiO, ZnO, MgO and CaO (abbreviated as Cu, Ni, Zn, Mg and Ca) were used as dopant to modify Fe2O3. The doped Fe2O3 were prepared via coprecipitation method and used for POX of VR. The physicochemical properties were characterized by various techniques and relationship between the performance of POX and the structure properties was revealed. Finally, a CLPOX was developed to realize effective recycle of spent solid oxidant.

2. EXPERIMENTAL 2.1. Materials preparation Co-precipitation was applied to synthesize MO (M2+=Cu, Ni, Zn, Mg and Ca) doped Fe2O3. Analytical grade reagents of Fe(NO3)3·9H2O, Cu(NO3)2·3H2O, Ni(NO3)2·6H2O, Zn(NO3)2·6H2O, Mg(NO3)2·6H2O, Ca(NO3)2·4H2O, and ammonia solution were used. In a typical synthesis process, Fe(NO3)3·9H2O and a certain amount of precursor of M2+ were dissolved with Fe/M atomic ratio of 16:1 in deionized water and then ammonia solution was added continuously under stirring at 30 oC to reach final pH value of 9.0. After ageing at 60 oC for 3 h, it was filtered and washed by using deionized water. Finally, it was dried at 110 oC for 12 h and calcined at 600 oC for 3 h. The samples were labelled as Fe2O3, Fe-Cu, Fe-Ni, Fe-Zn, Fe-Mg and Fe-Ca, respectively. 2.2. Partial Oxidation of VR Vacuum residue (VR), a typical heavy oil, from Chinese Daqing crude oil was used. The basic 3


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properties of VR has been reported9, as listed in Table S1. POX of VR was conducted on a fixed bed reactor at 550 oC under atmospheric pressure for 1 h as shown in Figure S1. The detailed procedure has been described in our previous study9. Briefly, a solution with 20 wt.% VR diluted with toluene was used as feedstock, and pumped into the reaction system by a micro-syringe (TJ3A, Longer Precision Pump Co., Ltd.). The total mass flow rate including VR and toluene is 5.0 g/h. Preliminary experiment showed that toluene was almost inert in the POX reaction with Fe2O3 based materials, which is consistent with the reported literatures23, 24. The weigh hourly space velocity (WHSV) defined as the mass ratio between weight flow rate of VR in feedstock and metal oxide loading is 0.8 h-1. Gas and liquid products were separated by ice trap. Analysis of gas composition was conducted on a gas chromatography (GC 7890 II, Shanghai Techcomp Instrument Ltd.) configured with thermal conductor detector (TCD) and flame ionization detector (FID), respectively. The weight difference between liquid condensate in ice trap and solvent in feedstock is the liquid product. The yield of liquid product was measured according to Equation (1): Liquid yield (wt%)=

Weight of liquid product VR weight

 100%

(1)

Fraction distribution was determined by a simulated distillation gas chromatograph (GC, SCION 456) equipped with FID. The gasoline, diesel, vacuum gas oil (VGO), heavy oil can be determined based on the following temperature range: IBP-180 oC, 180-350 oC, 350-500 oC, > 500 oC 25, 26. The heavy oil conversion was calculated as: Conversion (wt%)=(1  Heavy oil in liquid product/Heavy oil in VR )  100%

(2)

Coke-like material remained on the reactor wall is named as residue. It was calculated by the weight change of the reactor prior to and after reaction. Thermogravimetry (TG) analysis was conducted on a Mettler Toledo TGA/SDTA851e to determine coke deposition on spent samples. 4


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2.3. Materials characterization X-ray diffractometer (XRD) patterns were collected using a D/Max 2400 diffractometer. Specific surface area was calculated by Brunauer-Emmett-Teller (BET) analyses of N2 adsorption isotherms obtained on a JK-BK 122W. Raman spectroscopy was performed in a Thermo Fisher DXR Microscope. X-ray photoelectron spectroscopy (XPS) was obtained on a Thermo ScientificTM ESCALAB 250Xi. The morphologies were obtained on QUANTA 450.

3. RESULTS AND DISCUSSION 3.1. Partial Oxidation of VR Table 1 shows the POX performance of different doped samples. Blank test without the addition of Fe2O3 or using SiO2 as reference were conducted for comparison. Generally, cracking of VR with or without Fe2O3 samples can all result in the heavy oil conversion and production of gas, liquid and carbonaceous residue (residue and coke), but the heavy oil conversion and product distribution are different. For example, when SiO2 was used, heavy oil conversion, yields of gasoline, diesel and VGO are 66.1 wt%, 5.4 wt%, 16.4 wt%, 21.1 wt%, respectively. They increase significantly to 92.0 wt%, 8.0 wt%, 27.5 wt%, 29.9 wt%, respectively, when Fe2O3 was used. The heavy oil has a high conversion in all the doped Fe2O3 samples, but they exhibit significant differences in the product distribution. In the case of Fe-Cu, although the heavy oil conversion is 89.6 wt%, most of heavy oil is converted into residue being 39.8 wt%. The heavy oil conversion on Fe-Ni reaches 99.1 wt%, and the highest gas yield with 41.7 wt% can be obtained. This suggests that doping Ni can improve the gasification ability. When Fe-Mg, Fe-Ca and Fe-Zn were used, the gasoline, diesel and VGO yields increase as compared to the blank or with SiO2. Among these, FeCa shows the best POX performance with respect to the highest diesel oil of 39.2 wt%. In the case 5


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of gasoline and VGO yields on Fe-Ca, they are 8.5 wt% and 27.4 wt%, separately. The composition of gas from POX of VR is shown in Table 2. CH4 and C2H4 are the main gas product under the blank or SiO2 test. It has been reported that the CH3 radical is generated from the cleavage of alkyl chain, cycloalkane, and alkyl side chain attached to aromatic ring and naphthenic ring could combine with H radical to form CH427, 28. The β-scission of straight chain, side chain, and bridge on cycloalkane and aromatic leads to the formation of C2H427. The formation of CO2 without Fe2O3 is attributed to the carboxyl group decomposition. When Fe2O3 was added, the formation of CO2 increased significantly. This suggests that the Fe2O3 is served as oxidant by releasing active oxygen species to react with VR, thus, some carbon in VR can be consumed through the formation of CO2. The H2 content from POX of VR over the all Fe2O3 samples (except for Fe-Cu) is above 50 vol%. High H2 content has also been reported when ceria based materials were used in the upgrading of oil sand bitumen23. 3.2. Structure-activity Relationship As shown in Table 1 and 2, the MO doping can change the product distribution significantly, and different dopants show different POX performance. Several characterizations including XRD, N2 adsorption/desorption, Raman, and XPS were carried out to reveal the structure-activity relationship. Figure 1 shows XRD patterns of Fe2O3 samples. Diffraction peaks at 24.0, 33.0, 35.5, 40.7, 49.3, 54.0, 57.5, 62.3 and 63.9o are attributed to hematite phase (JCPDS 33-0664). Peaks corresponding to hematite were identified for all the doped Fe2O3 samples, suggesting that a small amount of dopant will not critically change the bulk crystalline structure of Fe2O3. No peaks attributed to CuO, NiO, MgO, CaO and ZnO were found, and peaks corresponding to ZnFe2O429, NiFe2O430 and 6


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MgFe2O431 were detected for Fe-Zn, Fe-Ni and Fe-Mg, respectively. It can be found that the diffraction peaks of Fe-Ca are broader and have lower intensities than those of Fe2O3, suggesting a smaller crystal size and lower degree crystallinity. Table 3 shows that the crystal size of doped Fe2O3 is smaller than that of Fe2O3. For example, the crystal size of the Fe-Ca and Fe2O3 are 24.3 and 38.7 nm, respectively. Figure 1b shows detail view in the 2θ range of 32.5-36.0o. The diffraction peaks assigned to face (111) and (110) shift to higher 2θ angle for Fe-Ni, Fe-Mg and Fe-Ca samples. The shift of 2θ angle for Fe-Ni and Fe-Mg is mainly attributed to the formation of NiFe2O4 and MgFe2O4. However, no CaFe2O4 on Fe-Ca sample was detected, which suggests that it could be highly dispersed on Fe2O3. Besides, it may be poorly crystalline, amorphous or undetectable amount by XRD32, 33. The formation of NiFe2O4, MgFe2O4, ZnFe2O4, and CaFe2O4 is contributed to the high conversion of heavy oil, but their roles are different. Based on the results shown in Table 1, the NiFe2O4 is benefit for high gas production, while the MgFe2O4, ZnFe2O4 and CaFe2O4 is benefit for high yield of diesel oil. As shown in Table 2, CO2 content increases when the Fe2O3 samples were used. This indicates that active oxygen species from Fe2O3 can react with VR, and the used Fe2O3 may undergo a crystal transition. Figure 2c shows the XRD patterns of spent samples. The crystal transition from oxidized state to the reduced state can be found in all the Fe2O3 samples, but the degree of change is different. For Fe2O3, Fe-Zn, Fe-Ca, Fe-Mg and Fe-Cu samples, the transition from hematite to magnetite structure occurs, and the diffraction peaks corresponding to FeO could be identified for Fe-Zn, FeCa and Fe-Mg samples. Fumoto et al19 found that the iron oxide shows a hematite structure before reaction and it changed to the magnetite structure after reaction. This suggests that Fe2O3 samples are served as solid oxidant to offer active oxygen species. In view of oxygen migration, the 7


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continuous removal of oxygen can cause the formation of oxygen vacancies on the surface34, accompanied with the generation of CO or CO2. The bulk lattice oxygen will relocate to the surface to fill the surface oxygen vacancies 35, 36 and oxygen vacancies move in the opposite direction37. As a result, the crystal transition occurs. It also has to be noted that the mobility of lattice oxygen is associated with the dopant used. Lim et al36 reported that transition metal including Fe, Mn, and Co doped perovskites shows different lattice oxygen transfer ability. The oxygen mobility from the bulk to the surface is in the order of Fe 20th Fe-Ca. TG analysis showed that the loss of active oxygen species can be regenerated when air is used as oxidation. Figure 8(a) shows the XRD patterns of Fe-Ca samples after they are regenerated. Compared with the fresh Fe-Ca, the other Fe-Ca samples from different cycles also exhibit hematite structure, indicating that active oxygen species can be replenished after treated at air condition. Two diffraction peaks at 30.1 and 62.8o emerge on the cycled samples, which are assigned to the formation of Ca2Fe2O5. According to the Raman spectra shown in Figure 8(b), the Fe-Ca samples from different cycles show the hematite structure, which is consistent with the XRD analysis. The morphologies changes with the number of cycles are recorded and shown in Figure 9. The 14


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particle size distribution on fresh Fe-Ca is uniform, but it has irregular morphology. As the number of cycle increases, the particle size and morphology change as compared to the fresh Fe-Ca. In the case of 20th Fe-Ca, the sintering and agglomeration of particle sizes can be observed. The textural properties shown in Table 5 reveal that the specific surface area and pore volume are lower than that of fresh Fe-Ca sample. The decrease of specific surface area and pore volume is mainly associated with sintering of particle sizes and pore collapse.

4. CONCLUSIONS Doped Fe2O3 samples have been synthesized and applied to POX of VR. The results showed that the Mg, Ca and Zn doping of Fe2O3 could increase diesel yield, and Ni doping increase the gas yield. The crystal transformation during the reaction is attributed to the loss of active oxygen species. It was found that the yield of liquid fuels is affected by the specific surface area and concentration of O- species. The Fe-Ca with largest specific surface area and high concentration of O- shows the best POX performance. The gasoline, diesel and VGO yields on Fe-Ca are 8.5 wt%, 39.2 wt% and 27.4 wt%, respectively. CLPOX using Fe-Ca as oxygen carrier revealed that the Fe-Ca exhibits good regenerability after 20th cycles. The gasoline, diesel and VGO yields at 20th cycle are 8.2 wt%, 30.3 wt% and 28.6 wt%, respectively. The replenishment of active oxygen species from air is contributed to maintain the hematite structure of Fe-Ca during 20 cycles.

ACKNOWLEDGEMENTS The authors acknowledge support from the Joint Found of Coal-based Low Hydrocarbons by NSFC and Shanxi Provincial Government of China (No. U1710105) and the Research Fund of the State Key Laboratory of Fine Chemistry (No. ZYTS201804). 15


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Oxygen Carriers for Chemical Looping Reforming: A DFT Study. Fuel 2018, 229, 88-94. 35. Chen, D.; He, D.; Lu, J.; Zhong, L.; Liu, F.; Liu, J.; Yu, J.; Wan, G.; He, S.; Luo, Y. Investigation of the Role of Surface Lattice Oxygen and Bulk Lattice Oxygen Migration of Cerium-Based Oxygen Carriers: XPS and Designed H2-TPR Characterization. Appl. Catal. B 2017, 218, 249-259. 36. Lim, H. S.; Lee, M.; Kang, D.; Lee, J. W. Role of Transition Metal in Perovskites for Enhancing Selectivity of Methane to Syngas. Int. J. Hydrogen Energ. 2018, 43 (45), 20580-20590. 37. Yao, X.; Tang, C.; Ji, Z.; Dai, Y.; Cao, Y.; Gao, F.; Chen, L. D. A. A. Investigation of the Physicochemical Properties and Catalytic Activities of Ce0.67M0.33O2 (M = Zr4+, Ti4+, Sn4+) Solid Solutions for NO Removal by CO. Catal. Sci. Technol. 2013, 3 (3), 688-698. 38. Zhu, X.; Li, K.; Wei, Y.; Wang, H.; Sun, L. Chemical-Looping Steam Methane Reforming over a CeO2–Fe2O3 Oxygen Carrier: Evolution of Its Structure and Reducibility. Energy Fuels 2014, 28 (2), 754-760. 39. Gu, Z.; Li, K.; Qing, S.; Zhu, X.; Wei, Y.; Li, Y.; Wang, H. Enhanced Reducibility and Redox Stability of Fe2O3 in the Presence of CeO2 Nanoparticles. RSC Adv. 2014, 4 (88), 47191-47199. 40. Yamashita, T.; Hayes, P. Analysis of XPS Spectra of Fe2+ and Fe3+ Ions in Oxide Materials. Appl. Surf. Sci. 2008, 254 (8), 2441-2449. 41. Radu, T.; Iacovita, C.; Benea, D.; Turcu, R. X-Ray Photoelectron Spectroscopic Characterization of Iron Oxide Nanoparticles. Appl. Surf. Sci. 2017, 405, 337-343. 42. Muhler, M.; Schlögl, R.; Ertl, G. The Nature of the Iron Oxide-Based Catalyst for Dehydrogenation of Ethylbenzene to Styrene 2. Surface Chemistry of the Active Phase. J. Catal. 1992, 138 (2), 413-444. 43. Mills, P.; Sullivan, J. L. A Study of the Core Level Electrons in Iron and Its Three Oxides by Means of X-Ray Photoelectron Spectroscopy. J. Phys. D: Appl. Phys. 1983, 16 (5), 723-732. 44. Sukonket, T.; Khan, A.; Saha, B.; Ibrahim, H.; Tantayanon, S.; Kumar, P.; Idem, R., Influence of the Catalyst Preparation Method, Surfactant Amount, and Steam on CO. Energy Fuels 2011, 25 (3), 864-877. 45. Cao, W.; Tan, O. K.; Pan, J. S.; Zhu, W.; Reddy, C. V. G. XPS Characterization of xα-Fe2O3(1-x) ZrO2 for Oxygen Gas Sensing Application. Mater. Chem. Phys. 2002, 75 (1-3), 67-70. 46. Liu, F.; He, H.; Ding, Y.; Zhang, C. Effect of Manganese Substitution on the Structure and 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

Activity of Iron Titanate Catalyst for the Selective Catalytic. Appl. Catal. B 2009, 93 (1), 37603769. 47. Aronniemi, M.; Sainio, J.; Lahtinen, J. XPS Study on the Correlation between Chemical State and Oxygen-Sensing Properties of an Iron Oxide Thin Film. Appl. Surf. Sci. 2007, 253 (24), 9476-9482. 48. Kawabe, T.; Shimomura, S.; Karasuda, T.; Tabata, K.; A, E. S.; Yamaguchi, Y. Photoemission Study of Dissociatively Adsorbed Methane on a Pre-oxidized SnO2 Thin Film. Surf. Sci. 2000, 2-3 (448), 101-107. 49. Ming, H.; Mingli, F.; Junliang, W.; Bichun, H.; Hong, L.; Daiqi, Y. Characteristic of Surface Oxygen Species and Catalytic Property on MnOx-CeO2 for Soot Combustion. J. Chin. Soc. Rare Earths 2011, 29 (3), 303-309. 50. N guyen, M.; Seriani, N.; Gebauer, R. Water Adsorption and Dissociation on α-Fe2O3 (0001): PBE+U Calculations. J. Chem. Phys. 2013, 138 (19), 194709. 51. Yatom, N.; Neufeld, O.; Caspary Toroker, M. Toward Settling the Debate on the Role of Fe2O3 Surface States for Water Splitting. J. Phys. Chem. C 2015, 119 (44), 24789-24795. 52. Devaiah, D.; Tsuzuki, T.; Aniz, C. U.; Reddy, B. M. Enhanced CO and Soot Oxidation Activity over Y-Doped Ceria–Zirconia and Ceria–Lanthana Solid Solutions. Catal. Lett. 2015, 145 (5), 1206-1216. 53. Uddin, M. A.; Tsuda, H.; Wu, S.; Sasaoka, E. Catalytic Decomposition of Biomass Tars with Iron Oxide Catalysts. Fuel 2008, 87 (4-5), 451-459. 54. Hosseinpour, M.; Fatemi, S.; Ahmadi, S. J. Deuterium Tracing Study of Unsaturated Aliphatics Hydrogenation by Supercritical Water in Upgrading Heavy Oil. Part II: Hydrogen Donating Capacity of Water in the Presence of Iron (III) Oxide Nanocatalyst. J. Supercrit. Fluid. 2016, 110, 75-82.

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Page 21 of 35 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

Table 1. Heavy oil conversion and product yields from POX of VR over different Fe2O3 samples Sample Blank *

Conversion and yields (wt%) Gas

Gasoline

Diesel

VGO

Heavy oil conversion

Residue

Coke

3.0

6.6

14.6

20.1

67.5

27.5

-

*

2.0

5.4

16.4

21.1

66.1

25.8

-

Fe2O3

7.0

8.0

27.5

29.9

92.0

18.9

1.8

Fe-Cu

4.9

5.0

18.5

22.8

89.6

39.8

#

Fe-Ni

41.7

2.4

9.3

5.9

99.1

14.1

25.8

Fe-Mg

7.2

8.0

34.5

30.4

94.1

10.1

4.7

Fe-Ca

9.7

8.5

39.2

27.4

97.6

5.4

7.7

Fe-Zn

7.8

7.4

31.6

30.9

94.8

14.9

SiO2

* Blank test means that no solid material was added in the reactor. Data from reported work, reference # Undetected by TG.

21


2.9 [9].

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 22 of 35

Table 2. Composition of gas from POX of VR over Fe2O3 samples Sample

Gas yield (mL/(g.VR)

Gas composition (vol%) CO2

CH4

C2H4

C2H6

C3H8

H2

CO

Blank

28

1.2

33.1

27.6

15.7

9.7

12.7

*

SiO2

23

0.5

36.1

22.6

17.4

10.1

13.3

*

Fe2O3

94

15.6

13.5

8.8

6.3

4.1

51.7

*

Fe-Cu

38

24.7

27.8

17.0

10.2

6.2

14.1

*

Fe-Ni

1060

6.9

3.4

0.3

0.5

0.3

72.8

15.8

Fe-Mg

105

13.4

14.0

5.0

3.8

2.7

61.1

*

Fe-Ca

156

10.7

11.7

5.7

3.9

2.9

65.1

*

Fe-Zn

122

13.3

15.3

6.5

4.5

3.2

57.2

*

* Undetected by GC.

22


Page 23 of 35 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

Table 3. Textural properties of Fe2O3 samples

*

Crystal size

SBET (m2/g)

Vp (cm3/g)

Dp (nm)

Fe2O3

13.0

0.128

39.6

38.7

Fe–Cu

5.0

0.035

11.3

34.9

Fe–Ni

12.7

0.106

24.2

30.5

Fe–Mg

14.4

0.118

21.3

31.8

Fe–Ca

29.2

0.145

13.1

24.3

Fe–Zn

9.9

0.091

22.9

Sample

Scherrer formula was used to calculate crystal size based on face (104) at

23


(nm)*

34.7 33o

from XRD

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 24 of 35

Table 4. Relative concentration of surface oxygen species on Fe2O3 samples Oxygen species (%) Sample

OI

OII

OI/OII

O2-

O-

OH-

O22-

Fe2O3

75.8

7.3

5.8

11.1

3.1

Fe-Cu

66.9

15.5

11.7

5.9

2.0

Fe-Ni

67.3

18.4

9.5

4.8

2.1

Fe-Mg

72.9

15.4

7.1

4.6

2.7

Fe-Ca

73.4

15.1

6.6

4.9

2.8

Fe-Zn

73.3

14.8

8.2

3.7

2.7

24


Page 25 of 35 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

Table 5. Textural properties of Fe-Ca samples Sample

SBET (m2/g)

Vp (cm3/g)

Fe-Ca

29.2

0.145

1 cycle Fe-Ca

14.6

0.109

10th

Fe-Ca

3.7

0.034

20th

Fe-Ca

5.0

0.044

25


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 captions Figure 1. XRD patterns of (a) Fe2O3 samples, (b) detail view between 32.5o and 36.0o, and (c) used Fe2O3 samples Figure 2. Raman spectra of Fe2O3 samples (a) and detail view between 220 and 325 cm-1 (b) Figure 3. XPS spectra of Fe 2p (a) and O 1s of Fe2O3 samples Figure 4. Correlation between the specific surface area and liquid yield Figure 5. TG (a) and DTG (b) curves of spent Fe2O3 samples Figure 6. Yields of gas, gasoline, diesel and VGO (a), gas formation (b) from CLPO of VR at different cycles Figure 7. TG curves of spent Fe-Ca samples from different cycles Figure 8. XRD patterns (a), and Raman spectra (b) of Fe-Ca samples from different cycles Figure 9. SEM morphologies of Fe-Ca (a), 1 cycle Fe-Ca (b), 10th Fe-Ca (c), and 20th Fe-Ca (d)

26


Page 26 of 35

Page 27 of 35

(a)Fe2O3 ○ZnFe2O4  NiFe2O4 □ MgFe2O4

(b)

Fe-Cu

Fe-Cu

□

□

Fe-Ni



□

Fe-Ca Fe-Zn Fe2O3

10



Intensity (a.u.)

Intensity (a.u.)

Fe-Mg



20

○ 

○ 

30

Fe-Zn (111)







60

▲

★



FeO





34 2θ (degree)

FeC







35

36

C

           

●

Fe-Ni

33

70

(c)  Fe2O3 □ Fe3O4 Fe-Cu

(110) Fe2O3





40 50 2θ (degree)

Fe-Mg Fe-Ca Fe-Zn

▲

▲

Intensity (a.u.)

Fe-Ca

○ ○

○



Fe-Mg

▲

Fe-Ni

●

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

□

Fe2O3 □

10

20

□

□

□ □

30 40 50 2θ (degree)

□

□

□

60

70

Figure 1. XRD patterns of (a) Fe2O3 samples, (b) detail view between 32.5o and 36.0o, and (c) used Fe2O3 samples

27


Energy & Fuels

(a)

(b) Fe-Cu

Fe-Cu

Fe-Mg Fe-Ca Fe-Zn

A1g E Eg g 150

300

Eg 450

A1g

Eg 600

Intensity (a.u.)

Fe-Ni

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

Page 28 of 35

Fe-Ni Fe-Mg Fe-Ca Fe-Zn Fe2O3

Fe2O3 -1

Raman shift (cm )

750

900 200

225

250

275

-1

Raman shift (cm )

300

Figure 2. Raman spectra of Fe2O3 samples (a) and detail view between 220 and 325 cm-1 (b)

28


325

Page 29 of 35

(a)

Intensity (a.u.)

Fe-Ni

Fe-Mg Fe-Ca Fe2O3 708

O O-

Fe-Cu Fe-Ni

Fe-Zn Fe 2p3/2

702

2-

(b)

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

Energy & Fuels

Satellite

Fe 2p1/2

-

OH O22-

Fe-Mg Fe-Ca Fe-Zn Fe2O3

714 720 726 Binding energy (eV)

732 526

528

530 532 534 Binding energy (eV)

Figure 3. XPS spectra of Fe 2p (a) and O 1s of Fe2O3 samples

29


536

Energy & Fuels

45 Gasoline Diesel VGO 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

Page 30 of 35

30

15

0

0

7 14 21 28 2 Specific surface area (m /g)

35

Figure 4. Correlation between the specific surface area and liquid yield

30


Page 31 of 35

0.001

(a)

(b)

o

Rate of Weight Loss (%/ C)

105

100

Weight (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

Fe2O3 Fe-Cu Fe-Ni Fe-Mg Fe-Ca Fe-Zn

95

90

0.000 Fe2O3

-0.001

Fe-Cu Fe-Ni Fe-Mg Fe-Ca Fe-Zn

-0.002 -0.003

85

200

400 600 o Temperature ( C)

800

200

400 600 o Temperature ( C)

Figure 5. TG (a) and DTG (b) curves of spent Fe2O3 samples

31


800

Energy & Fuels

(a)

Gas VGO

100

Gasoline Diesel

Gas volume (mL/gꞏVR)

40 30 Yiled (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

20 10 0

0

5

10 Cycle

15

20

Page 32 of 35

(b)

75

CO2

CH4

C2H4

C2H6

C3H8

H2

50

25

0

0

5

10 Cycle

15

20

Figure 6. Yields of gas, gasoline, diesel and VGO (a), gas formation (b) from CLPO of VR at different cycles

32


Page 33 of 35

102

100 Weight (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

98 1 cycle Fe-Ca th 10 Fe-Ca th 20 Fe-Ca

96 150

300 450 600 o Temperature ( C)

750

Figure 7. TG curves of spent Fe-Ca samples from different cycles

33


Energy & Fuels

(a)

 Fe O 2 3

th



20 Fe-Ca

 Ca2Fe2O5

Fe

(b)

O4

3





th

20 Fe-Ca

th

th

10 Fe-Ca

10 Fe-Ca Intensity (a.u.)

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

Page 34 of 35

1 cycle Fe-Ca 

Fe-Ca 10

20

 



30



40 50 2θ (degree)

 

A1g E g Eg

Eg



60

1 cycle Fe-Ca

70 150

300

A1g

Eg

Fe-Ca

450 600 750 -1 Raman shift (cm )

Figure 8. XRD patterns (a), and Raman spectra (b) of Fe-Ca samples from different cycles

34


900

Page 35 of 35 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

Figure 9. SEM morphologies of Fe-Ca (a), 1 cycle Fe-Ca (b), 10th Fe-Ca (c), and 20th Fe-Ca (d)

35


Upgrading of Heavy Oil with Chemical Looping Partial Oxidation over

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