Deep oxidative desulfurization of model fuel via dielectric barrier discharge plasma oxidation using MnO2 catalysts and combination of ionic liquid extraction

Article abstract of DOI:10.1016/j.cattod.2013.02.009

This paper developed a novel oxidative desulfurization (ODS) technique via dielectric barrier discharge plasma oxidation using MnO₂ catalysts and a combination of ionic liquid [BMIM]CH₃COO extraction. MnO ₂ catalysts were synthesized using hydrothermal synthesis and characterized using various analytical techniques. Their ODS performances were investigated. The results indicated that MnO₂ catalysts could effectively improve the performance of the desulfurization system. Under optimized technical conditions, the sulfur removal of thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in n-octane reached 99.9%, 99.9%, 97.9%, and 90.7%, respectively. The oxidation activities of the four sulfur compounds decreased in the order of TS > BT > DBT > 4,6-DMDBT.

Full text of DOI:10.1016/j.cattod.2013.02.009

Catalysis Today 211 (2013) 84–89
Contents lists available at SciVerse ScienceDirect
Catalysis Today
journal homepage: www.elsevier.com/locate/cattod
Deep oxidative desulfurization of model fuel via dielectric barrier
discharge plasma oxidation using MnO2 catalysts and combination of
ionic liquid extraction
Cunhua Maa,b, Bin Daib,∗, Caixia Xua,b, Ping Liub, Liangliang Qib, Lili Banb
a School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China
b School of Chemistry and Chemical Engineering, Shihezi University, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bintuan,
Shihezi, Xinjiang 832003, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
This paper developed a novel oxidative desulfurization (ODS) technique via dielectric barrier discharge
plasma oxidation using MnO2 catalysts and a combination of ionic liquid [BMIM]CH3COO extrac-
tion. MnO2 catalysts were synthesized using hydrothermal synthesis and characterized using various
analytical techniques. Their ODS performances were investigated. The results indicated that MnO2
catalysts could effectively improve the performance of the desulfurization system. Under optimized
technical conditions, the sulfur removal of thiophene (TS), benzothiophene (BT), dibenzothiophene
(DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in n-octane reached 99.9%, 99.9%, 97.9%, and
90.7%, respectively. The oxidation activities of the four sulfur compounds decreased in the order of
TS > BT > DBT > 4,6-DMDBT.
Received 1 December 2012
Received in revised form 17 February 2013
Accepted 20 February 2013
Available online 24 March 2013
Keywords:
Oxidative desulfurization
Model fuel
DBD plasma
MnO2
© 2013 Elsevier B.V. All rights reserved.
[BMIM] CH3COO
1. Introduction
using suitable extractants. Most ODS studies use hydrogen perox-
ide as an oxidizing agent [18–20]. It can decompose into water and
The sulfur (S) compounds in transportation fuels are considered
as a major source of SOx that can cause acid rain and air pollu-
tion [1,2]. To deal with increasingly critical atmospheric pollution,
governments worldwide are imposing more stringent regulations
to restrict sulfur concentration in transportation fuels and reduce
SOx emissions [3–6]. Euro 5 emissions standard, which has been
enforced in Europe since September 2009, regulates the use of
“sulfur-free” diesel and gasoline fuels (≤10 ppm S). This directive
has also been adopted in the USA since 2010. Producing clean
fuels is currently a difficult and challenging subject for researchers
worldwide.
Aside from hydro-desulfurization (HDS) [7–9], other non-
hydrogenation desulfurization technologies, including adsorption
[10,11], extraction [12,13], and oxidation [14,15], have been
developed in recent years. Among these technologies, oxidative
desulfurization (ODS) is considered as one of the most promising
methods for deep desulfurization. In this method, the S compounds
in the fuels are oxidized into their corresponding sulfones and/or
sulfoxides [16,17], and the resulting compounds are then removed
form an oil–aqueous solution biphasic system [21], which elicits a
negative effect on the ODS system.
By contrast, if a gas is selected as an oxidant in the ODS process
of fuel, oil–aqueous biphasic problems do not occur. At present,
some studies use ozone [22] and molecular oxygen [23,24] as oxi-
dizing agents. Dielectric barrier discharge (DBD) is a gas discharge
process that has been widely used for treatment of exhaust gases
and wastewater, surface modification and the generation of ozone
from air or oxygen [25]. Compared to other plasma techniques,
DBD has some advantages such as working well at atmospheric
pressure, without vacuum restrictions, simple and flexible config-
urations with respect to the geometrical shape of electrodes and
the gap [26]. Air is a low-cost and environmentally benign oxy-
gen source [27]. When air is ionized by DBD plasma under strong
voltage, it can generate ozone and abundant •O, •O−, •O2 etc.
−
free radicals [28] as strong oxidizing agents that can oxidize sulfur
compounds into corresponding sulfoxides and/or sulfones. Desul-
furization performance can be promoted when combined with the
appropriate catalysts. With the small particle size, strong sorp-
tion capability, and high catalytic oxidation activity, MnO2 catalysts
have attracted increasing attention in recent years [29,30]. MnO2,
which is an absorbent and a catalyst, is applied to remove organic
pollutants. Furthermore, ionic liquid (IL) [31,32] is also widely used
∗
Corresponding author. Tel.: +86 0993 2058176; fax: +86 0993 2057270.
E-mail address: db tea@shzu.edu.cn (B. Dai).
0920-5861/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.cattod.2013.02.009

C. Ma et al. / Catalysis Today 211 (2013) 84–89
85
Fig. 1. Schematic diagram for catalytic oxidation desulfurization process.
as an extractant for fuel desulfurization because of its high affin-
ity to sulfur compounds or oxidative products (sulfoxides and/or
sulfones).
for 6 h at approximately 150 ◦C before measurements, and specific
areas were measured by BET equation.
This study synthesized different crystalline forms of
MnO2 catalysts. Their structures were characterized by
Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD),
and scanning electron microscopy (SEM). At the same time, their
catalytic ODS performances by DBD plasma oxidation using air as
feed gas combined with [BMIM]CH3COO ([BMIM]Ac) extraction
under ambient pressure and moderate temperature were inves-
tigated. In addition, important factors influencing sulfur removal,
such as oxidation time, air flow rate, input current, extraction
time, catalyst amount, and extraction temperature were also
investigated.
2.3. Experimental apparatus
The schematic diagram of the experimental apparatus for the
catalytic ODS procedure are shown in Fig. 1. The apparatus includes
a DBD wire-cylinder reactor, a plasma generator (CTP-2000K, Nan-
jing Suman electronic Co., Ltd.), a mass flow controller, and a ODS
reactor. The wire-cylinder reactor was made up of quartz (inner
diameter: 19 mm; outer diameter: 23 mm) inside of which a 3 mm
thick steel rod was placed and outside of which a layer of steel net
was covered. The AC high voltage (HV) electrode was applied to
the steel rod, and the low voltage (LV) electrode was applied to
the steel net with the two electrodes 8 mm apart. Air controlled by
mass flow controller passed through the DBD reactor at a certain
flow rate. When the voltage between two electrodes was higher
than the breakdown voltage of air, plasma was generated. It could
rapidly and continually generate fresh ozone and •O, •O−, •O2− etc.
2. Experimental
2.1. Materials and methods
All compounds were purchased from Aldrich/J&K Chemical Ltd.
and used without any further treatment. Model fuel was prepared
by dissolving thiophene (TS), benzothiophene (BT), dibenzothio-
phene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in
n-octane to provide a solution with sulfur contents of 500, 500, 107,
and 94 ppm, respectively.
2.4. Catalytic desulfurization experiments
As shown in Fig. 1, the catalytic oxidation experiment was con-
ducted in 10 mL two-necked flasks equipped with a condenser, and
the fuel-to-catalyst weight ratio was 200. DBD air plasma including
ozone and •O, •O−, •O2− etc. free radicals generated by DBD plasma
in a quartz tube where air passed at a flow rate of 150 mL min
was bubbled up throughout the mixture using a magnetic stirrer
at room temperature. After being oxidized for a certain time, the
catalyst was filtered, and [BMIM]Ac was added into the flask with a
fuel-to-IL weight ratio of 10 using a magnetic stirrer at room tem-
perature for a certain time. After the desired reaction time was
reached, the upper oil phase was periodically withdrawn, and the
sulfur concentration was analyzed by microcoulometry (WK-2D,
Jiangsu Jiangfen Electroanalytical Instrument Co., Ltd., China).
2.2. MnO2 catalysts preparation and characterization
MnO2 catalysts with different crystalline forms, morphologies,
and particle sizes were prepared by redox reaction between KMnO4
and MnSO4, (NH4)2S2O8 and MnSO4, and KMnO4 and Mn(NO3)2
as manganese sources by hydrothermal synthesis as indicated in
literature [33–35].
The structural properties of the prepared catalysts were mea-
sured using various analytical and characterization methods. The
morphology of MnO2 was characterized by SEM (JSM-6490LV, Elec-
tronic Company in Japan) at 10 kV. The crystal structures of the
samples were measured using powder XRD (D8 ADVANCE, Bruker
Company in Germany) in the scan range of 2ꢀ between 10 and
80 with Cu Ka radiation at 40 kV and 40 mA. The isotherms were
determined by an ASAP 2020C surface area and porosity analyzer
(Micromeritics Instrument Corporation, USA) with liquid nitrogen
adsorption at approximately −196 ◦C. The samples were degassed
3. Results and discussion
3.1. Characterization of MnO2 catalysts
The powder XRD patterns of the MnO2 catalysts are shown in
Fig. 2. Different crystallographic phases of MnO2 catalysts were
obtained with different manganese sources. Alpha (␣), beta (␤), and
gamma (␥) MnO2 catalysts could be synthesized by redox reaction

86
C. Ma et al. / Catalysis Today 211 (2013) 84–89
Table 1
DBT removal at different desulfurization systems.
Entry
Desulfurization system
DBT removal (%)
(1)
(2)
(3)
DBD + [BMIM]Ac
␣-MnO2 (S3)
DBD + ␣-MnO2 (S3) + [BMIM]Ac
3.05
8.97
97.9
and S6 showed that hydrothermal reaction temperature elicited
no effect on surface topography of ␣-MnO2, but the particle size of
␣-MnO2 became larger with the increase of temperature.
3.2. Desulfurization comparisons at different desulfurization
systems
DBT was selected as S compound representative in fuels by HDS
treatment. Thus, these catalytic ODS experiments were conducted
using this substrate. To evaluate the catalytic activities of MnO2
catalysts, we selected ␣-MnO2 catalyst (S3) and designed different
desulfurization systems: oxidation by DBD air plasma combined
with IL extraction, simple adsorption by ␣-MnO2 (S3), and catalytic
oxidation by DBD air plasma with ␣-MnO2 (S3) as catalyst com-
bined with IL extraction. The results are listed in Table 1. When
␣-MnO2 was used as an adsorbent for the model oil, DBT removal
was only 8.97%. Sulfur removal was only 3.05% via oxidation by
air DBD and extraction by IL. With the addition of ␣-MnO2 cata-
lyst, DBT removal increased sharply, and the desulfurization rate of
97.9% was achieved through catalytic oxidation with air DBD and
extraction with IL. This result indicated that ␣-MnO2 showed a good
catalytic reactivity through this catalytic oxidation desulfurization
system at mild conditions.
Fig. 2. XRD patterns of MnO2 catalysts.
between KMnO4 and MnSO4, (NH4)2S2O8 and MnSO4, and KMnO4
and Mn(NO3)2 as manganese sources by hydrothermal synthesis
at 160 ◦C for 8 h (Fig. 2 S1, S2, and S5), respectively. The main
diffraction peaks were the same as the standard card of ␣-MnO2
(JCPDS 44-141), ␤-MnO2 (JCPDS 24-735), and ␥-MnO2 (14-644)
with almost the same peak resolution. In the redox reaction sys-
tem between KMnO4 and MnSO4 as manganese sources, changing
the hydrothermal temperature from 100 ◦C to 180 ◦C had almost
no effect on the ␣-MnO2 crystallographic phases for 8 h (Fig. 2 S3,
S4, S5, and S6), but the intensity of the main diffraction peaks of
␣-MnO2 increased with the hydrothermal temperature increasing,
indicating the particle size of ␣-MnO2 became larger with the tem-
perature rising, which could be further proved by the comparison
of SEM images of S3, S4, S5 and S6 (Fig. 3).
3.3. Desulfurization comparisons of different MnO2 catalysts
Fig. 3 shows SEM images of S1 to S6 MnO2 samples. As shown
in the figure, ␣-, ␤-, and ␥-MnO2 samples (S1, S2, and S3) showed
similar needle-like microstructures, but the difference in the crys-
tallographic phases is seen in the diameter of the needle. The
diameter of ␣-MnO2 catalyst was approximately 98 nm, which is
smaller than that of ␤-MnO2 (160 nm) and roughly the same size
as that of ␥-MnO2 (89 nm). In addition, SEM images of S3, S4, S5,
Table 2 presents the results obtained during ODS of DBT using
six different catalysts in MnO2–DBD–[BMIM]Ac systems. We found
that ␣-MnO2 and ␤-MnO2 had higher catalytic activity (≥94.1% sul-
fur removal) than ␥-MnO2 (only 50.0% sulfur removal). And the
catalytic activity of ␣-MnO2 prepared from different hydrothermal
temperatures decreased slightly from 100 to 160 ◦C. Among them,
␣-MnO2 (S3) had the maximum desulfurization ratio (97.9%). Li
Fig. 3. SEM images of MnO2 samples.

C. Ma et al. / Catalysis Today 211 (2013) 84–89
87
Table 2
Sulfur removal of DBT by different catalysts.
Samples
Manganese sources
Crystal structure
Hydrothermal temperature (◦C)
Hydrothermal time (h)
DBT removal (%)
S1
S2
S3
S4
S5
S6
KMnO4 + Mn(NO3)2
(NH4)2S2O8 + MnSO4
KMnO4 + MnSO4
KMnO4 + MnSO4
KMnO4+ MnSO4
KMnO4 + MnSO4
␥-MnO2
␤-MnO2
␣-MnO2
␣-MnO2
␣-MnO2
␣-MnO2
160
160
100
140
160
180
8
8
8
8
8
8
50.0
94.7
97.9
96.8
94.1
94.3
and co-workers [36] had reported that the decomposition of O3 on
MnO2 catalyst is consisted of two steps: the adsorption of O3 on the
surface of catalyst and desorption of O* from the surface of catalyst,
and the specific reaction steps are expressed by Eqs. (1)–(3), where
* denotes active sites on the surface of catalyst. This suggested that
the oxygen species O* and O2* formed plays an important role
in this process of catalytic oxidation desulfurization. Further, the
amount of active sites * on the surface of different kinds of MnO2
will be key factor, so the surface area and average pore size of MnO2
should have a significant impact on catalytic activity.
O3
+
→ O2 + O∗
(1)
(2)
(3)
∗
O3 + O∗ → O2 + O2
∗
∗
O2 → O2 +∗
Fig. 4. Effect of the oxidation time on DBT removal. Experimental conditions: 3 mL
model oil (S-content 107 ppm), m(fuel)/m(catalyst) = 200, input voltage = 30 V, input
current = 0.9–1.15 A, air flow rate = 150 mL min, m(fuel)/m(IL) = 10, extraction tem-
perature = 25 ◦C.
As the Table 3 shown, ␣-MnO2 (S3) has a higher surface area
than ␤-MnO2, simultaneously ␣-MnO2 has a larger average pore
size than ␥-MnO2, which made more high activity O* and O2* to
disperse surface of ␣-MnO2 to oxidizing original sulfur compounds.
This may be important reasons resulting in higher catalytic activity.
between oxidation products and [BMIM]Ac was achieved after a
few minutes regardless of the oxidation time (10, 20, 30, or 40 min).
DBT removal increased slightly in a follow up 90 min extraction
time. Oxidation played a key role in this study. DBTO and/or DBTO2
could be extracted by [BMIM]Ac as long as DBT is oxidized into
DBTO and/or DBTO2 completely under DBD air plasma.
Input current also significantly influenced DBT removal. As
shown in Fig. 5, desulfurization rate increased with increasing
input current and reached 96% when input current was increased
to 0.95 A. When input current was continually kept at 1.15 A, 97.9%
S removal was obtained. The most possible reason was that the
discharge intensity was enhanced between high-voltage electrode
and low-voltage electrode with increasing input current while
keeping a constant distance between two electrodes. Under a
3.4. Optimization of oxidative and extractive processes for DBT
removal
Model fuel including DBT was also selected as a representative
to optimize the desulfurization processes. The effect of oxidation
time by DBD air plasma on DBT removal was examined initially. The
results are shown in Fig. 4. DBD air plasma oxidation was a very cru-
cial step on DBT removal. The DBT removal only reached 2–3% after
90 min of extraction time using a simple extraction by [BMIM]Ac in
the absence of DBD air plasma oxidation. This result implied that
DBT was insoluble in [BMIM]Ac. After DBT was oxidized for 10 min,
sulfur removal markedly increased to 45%. DBT removal increased
slightly to 48% when oxidation time was increased to 20 min. How-
ever, when oxidation time was increased to 30 min, DBT removal
increased sharply to 97.9%. This result indicated that the oxidation
products sulfones (DBTO) and/or sulfoxide (DBTO2) of DBT tended
to dissolve in IL [BMIM]Ac. As shown in Fig. 4, a 30 min of oxidation
time is enough to obtain high sulfur removal. The reason that DBT
was insoluble but its oxidation products DBTO and/or DBTO2 was
soluble in [BMIM]Ac could be attributed to the theory of “similar-
ity and intermiscibility”. The polarity of DBTO and/or DBTO2 was
larger than that of DBT, it was remained easily in the strongly polar
[BMIM]Ac.
Meanwhile, extraction time by [BMIM]Ac was investigated in
different oxidation times. As shown in Fig. 4, extraction equivalent
Table 3
Textural properties of the MnO2 catalysts.
Samples
Surface area
(m2/g)
Pore volume
(cm3/g)
Average pore
size (Å)
Fig. 5. Effect of the input current on DBT removal. Experimental conditions: 3 mL
model oil (S-content 107 ppm), m(fuel)/m(catalyst) = 200, oxidation time = 30 min,
input voltage = 30 V, air flow rate = 150 mL·min, m(fuel)/m(IL) = 10, extraction tem-
perature = 25 ◦C.
␥-MnO2
␤-MnO2
␣-MnO2 (S3)
30.6
7.6
23.9
0.0625
0.0257
0.0576
81.7
135.5
96.4

88
C. Ma et al. / Catalysis Today 211 (2013) 84–89
Fig. 8. Effect of the extraction temperature on the DBT removal. Experimen-
tal conditions: 3 mL model oil (S-content 107 ppm), m(fuel)/m(catalyst) = 200,
oxidation time = 30 min, input voltage = 30 V, input current = 0.9–1.15 A, air flow
rate = 150 mL·min, m(fuel)/m(IL) = 10.
Fig. 6. Effect of the air flow rate on DBT removal. Experimental conditions: 3 mL
model oil (S-content 107 ppm), m(fuel)/m(catalyst) = 200, oxidation time = 30 min,
input voltage = 30 V, input current = 0.9–1.15 A, m(fuel)/m(IL) = 10, extraction tem-
perature = 25 ◦C.
amount of catalyst increased to 0.01 g [m(oil)/m(catalyst) = 200]. As
the amount of catalyst was set to 0.05 g [m(oil)/m(catalyst) = 40],
approximately 97.9% DBT removal was reached.
strong discharge, more ozone and activity species were generated,
which made the oxidation process more thorough. Therefore, the
optimal input current was kept between 0.95 and 1.15 A in the
next experiment.
After DBT in n-octane was oxidized into DBTO and/or DBTO2 by
DBD air plasma using MnO2 as catalyst for 30 min, the extraction of
DBTO and/or DBTO2 by [BMIM]Ac was carried out at different tem-
peratures (25, 40, 60, and 80 ◦C) in a 90 min time range. As shown
in Fig. 8, extraction temperature was one of the important factors
affecting DBT removal. The higher the extraction temperature was,
the lower the DBT removal was. That is, the extraction process was
exothermic, and 97.9% DBD removal could be achieved at room
temperature (25 ◦C). Therefore, room temperature was selected as
the optimal extraction temperature in the present study, which was
beneficial in industrial applications because of its energy saving and
low cost.
The effect of air flow rate on DBT removal was investigated. The
result is indicated in Fig. 6. S removal initially increased sharply
from 74.3% to 96.6% as air flow rate increased from 35 mL min to
90 mL min−1, stabilized around 97% as air flow rate increased from
90 mL min−1 to 190 mL min, and finally tended to decrease as air
flow rate increased to more than 190 mL min. This finding may be
attributed to the fact that the oxidizing agent generated by DBD air
plasma in the oxidation process was inadequate in unit time when
air flow rate was too small. By contrast, if air flow rate was too
large, activity species lost their activity once they combined with
excess air. The two reasons both made the oxidation reaction of DBT
incomplete, thereby decreasing desulfurization rate. The optimum
air flow rate in this work was 150 mL min.
3.5. Effect of different S-compounds in this desulfurization system
The amount of MnO2 catalyst was another important factor
investigated. As shown in Fig. 7, the amount of MnO2 had remark-
able effects on DBT removal. Only 48% DBT removal was reached
when 0.005 g catalyst was added into the oxidation system. How-
ever, the desulfurization rate of DBT increased to 97.1% as the
The effect of different substrates such as TS, BT, DBT, and
4, 6-DMDBT on ODS in the MnO2–DBD–[BMIM]Ac system was
studied under the same experimental conditions. As shown in
Fig. 9, TS, BT, and DBT removal reached 99.9%, 99.9%, and 97.9%
after 20, 30, and 30 min of oxidation, respectively, whereas 4,6-
Fig. 7. Effect of the amount of catalyst on the DBT removal. Experimental conditions:
3 mL model oil (S-content 107 ppm), oxidation time = 30 min, input voltage = 30 V,
input current = 0.9–1.15 A, air flow rate = 150 mL min, m(fuel)/m(IL) = 10, extraction
temperature = 25 ◦C.
Fig. 9. Effect of different S compounds in this desulfurization system. Experimental
conditions: 3 mL model oil, m(fuel)/m(catalyst) = 200, oxidation time = 30 min,
input voltage = 30 V, input current = 0.9–1.15 A, air flow rate = 150 mL min,
m(fuel)/m(IL) = 10, extraction temperature = 25 ◦C.

C. Ma et al. / Catalysis Today 211 (2013) 84–89
89
DMDBT removal only reached 90.7% after 60 min of oxidation. The
oxidation activities of the four sulfur compounds decreased in the
order of TS > BT > DBT > 4,6-DMDBT in the present desulfurization
system. The oxidation activities of TS and BT were higher than
that of DBT in the present study. This sequence was contrary
to most reports of other authors on ODS but was consistent in
the report of Ma. This study and Ma’s study [21] investigated
a gas–solid–oil tri-phasic system using gas as oxidant, whereas
other reports involved a solid–oil–water tri-phasic system using
H2O2 as oxidant. Ma [21] inferred that the use of different systems
might be one of the reasons for the different activity sequences.
[5] C. Sentorun-Shalaby, S.K. Saha, X. Ma, C. Song, Applied Catalysis: B: Environ-
mental 101 (2011) 718.
[6] E. Ito, J.A. Rob van Veen, Catalysis Today 116 (2006) 446.
[7] J.A. Cecilia, A. Infantes-Molina, E. Rodríguez-Castellón, A. Jiménez-López, Jour-
nal of Catalysis 263 (2009) 4.
[8] R. Navaa, B. Pawelec, J. Morales, R.A. Ortega, J.L.G. Fierro, Microporous and
Mesoporous Materials 118 (2009) 189.
[9] E. Soghratia, M. Kazemeini, A.M. Rashidi, K.J. Jozani, Procedia Engineering 42
(2012) 1484.
[10] L. Huang, G. Wang, Z. Qin, M. Dong, M. Du, H. Ge, X. Li, Y. Zhao, J. Zhang, T. Hu,
J. Wang, Applied Catalysis: B: Environmental 106 (2011) 26.
[11] V. Selvavathi, V. Chidambaram, A. Meenakshisundaram, B. Sairam, B.
Sivasankar, Catalysis Today 141 (2009) 99.
[12] C. Asumana, G. Yu, X. Li, J. Zhao, G. Liu, X. Chen, Green Chemistry 12 (2010)
2030.
[13] H. Zhang, J. Gao, H. Meng, C. Li, Industrial and Engineering Chemistry Research
51 (2012) 6658.
4. Conclusions
[14] S. Kumara, V.C. Srivastava, R.P. Badoni, Fuel Processing Technology 93 (2012)
18.
[15] B. Zapata, F. Pedraza, M.A. Valenzuela, Catalysis Today 106 (2005) 219.
[16] O. González-García, L. Ceden˜o-Caero, Catalysis Today 148 (2009) 42.
[17] L.C. Caeroa, E. Hernández, F. Pedraza, F. Murrieta, Catalysis Today 107/108
(2005) 564.
[18] H. Kok-Giap, A.W.A.B. Wan, A. Rusmidah, C. Jiunn-Fat, A.A.K. Abdul, Fuel Pro-
cessing Technology 91 (2010) 1105.
[19] M. Gürüa, B.V. Sariöz, C¸ . C¸ akanyildirim, Energy Sources Part A: Recovery, Uti-
lization, and Environmental Effects 30 (2008) 981.
[20] F. Carrillo-Pedroza, M. Soria-Aguilar, Energy and Fuels 23 (2009) 3703.
[21] X. Ma, A. Zhou, C. Song, Catalysis Today 123 (2007) 276.
[22] J.L. Wang, D.S. Zhao, K.X. Li, Energy and Fuels 24 (2010) 2527.
[23] S. Murata, K. Murata, K. Kidena, M. Nomura, Energy and Fuels 18 (2004) 116.
[24] H. Lü, J. Gao, Z. Jiang, Y. Yang, B. Song, C. Li, Chemical Communications (2007)
150.
[25] S. Liu, M. Neiger, Journal of Physics D: Applied Physics. 34 (2001) 1632.
[26] N. Dumitrascu, I. Topala, G. Popa, IEEE Transactions on Plasma Science 33 (2005)
1710.
[27] W. Guo, C. Wang, P. Lin, X. Lu, Applied Energy 88 (2011) 175.
[28] R. Seeböck, H. Esrom, M. Charbonnier, M. Romand, Plasmas and Polymers 5
(2000) 103.
[29] D.H. Wang, S. Zhang, J.H. Xia, Advances in Materials Research 402 (2011) 452.
[30] J.T. Sampanthar, H. Xiao, J. Dou, T.Y. Nah, X. Rong, W.P. Kwan, Applied Catalysis:
B: Environmental 63 (2006) 85.
ODS of S compounds was studied in the presence of MnO2 cat-
alyst, with DBD air plasma atmosphere oxidation coupled with
[BMIM]Ac extraction. The results indicated that this desulfuriza-
tion system was highly effective and that the sulfur removal of TS,
BT, DBT, and 4,6-DMDBT in n-octane reached 99.9%, 99.9%, 97.9%,
and 90.7% at ambient conditions, respectively. Moreover the oxi-
dation activities of the four sulfur compounds decreased in the
order of TS > BT > DBT > 4,6-DMDBT. This ODS method had remark-
able advantages, such as efficiency, energy saving, environmentally
friendly, and so on. Meanwhile, the fuel was easy to recover, and
the quality of fuel was not affected because no aqueous phase was
present.
Acknowledgements
This work was financially supported by the National Natu-
ral Science Foundation of China (No. 21063012) and Program for
Changjiang Scholars and Innovative Research Team in University
(Grant No. IRT1161).
[31] F. Li, R. Liu, J. Wen, D. Zhao, Z. Sun, Y. Liu, Green Chemistry 11 (2009) 883.
[32] L. Alonso, A. Arce, M. Francisco, O. Rodríguez, A. Soto, AIChE Journal 53 (2007)
3108.
[33] M. Zhu, Y. Hu, Y. Li, H. Jin, Z. Zhu, Physica Status Solidi C 9 (2012) 122.
[34] X. Wang, Y. Li, Journal of the American Chemical Society 124 (2002) 2880.
[35] C. Wu, Y. Xie, D. Wang, J. Yang, T. Li, Journal of Physical Chemistry B 107 (2003)
13583.
References
[1] R.T. Yang, A.J. Hernández-Maldonado, F.H. Yang, Science 301 (2003) 79.
[2] F. Al-Shahrani, T. Xiao, S.A. Llewellyn, S. Barri, Z. Jiang, H. Shi, G. Martinie, M.L.H.
Green, Applied Catalysis: B: Environmental 73 (2007) 311.
[3] P.S. Kulkarni, C.A.M. Afonso, Green Chemistry 12 (2010) 1139.
[4] Y.L. Zhang, Y.X. Yang, H.X. Han, M. Yang, L. Wang, Y.N. Zhang, Z.X. Jiang, C. Li,
Applied Catalysis: B: Environmental 119 (2012) 13.
[36] W. Li, G.V. Gibbs, S. Ted Oyama, Journal of the American Chemical Society 120
(1998) 9045.