Metathesis of butene to propene on WO3 supported on MTS-9 titanium-silica: Effect of loading on selectivity of product and yield of propene

Article abstract of DOI:10.1007/s11243-010-9458-7

An advanced heterogeneous catalyst for olefin disproportion was prepared by supporting WO₃ on titaniumsilica sieve (MTS-9). The nature of the surface tungsten oxide species present in these catalysts was determined as a function of tungsten oxide loading by X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectra (UV-DRS) and ultraviolet-visible Raman (UV-Raman). The catalyst showed high activity for the metathesis of butene to propene. The active centers are not crystallites of WO₃ but rather surface tungsten oxide species. The conversion of butene varies with the degree of catalyst loading. Springer Science+Business Media B.V. 2011.

Full text of DOI:10.1007/s11243-010-9458-7

Transition Met Chem (2011) 36:245–248
DOI 10.1007/s11243-010-9458-7
Metathesis of butene to propene on WO3 supported on MTS-9
titanium-silica: effect of loading on selectivity of product and yield
of propene
•
Derun Hua Sheng-Li Chen Guimei Yuan
•
•
•
Yulong Wang Li Zhang
Received: 26 November 2010 / Accepted: 29 December 2010 / Published online: 17 February 2011
Ó Springer Science+Business Media B.V. 2011
Abstract An advanced heterogeneous catalyst for olefin
disproportion was prepared by supporting WO3 on titanium-
silica sieve (MTS-9). The nature of the surface tungsten
oxide species present in these catalysts was determined as a
function of tungsten oxide loading by X-ray diffraction
(XRD), ultraviolet–visible diffuse reflectance spectra
(UV–DRS) and ultraviolet–visible Raman (UV-Raman).
The catalyst showed high activity for the metathesis of
butene to propene. The active centers are not crystallites of
WO3 but rather surface tungsten oxide species. The con-
version of butene varies with the degree of catalyst loading.
oxygen. The metathesis of butene to propene has attracted
considerable attention in recent years, due to the increased
demand for propene. Huang et al. [5] used ethene and
butene as starting materials to synthesize propene on
W/Al2O3–HY, achieving up to 63% 2-butene conversion at
180 °C. Liu et al. [6] reported the use of catalyst prepared
under moist atmosphere on the metathesis of butene and
ethene to propene. To save ethene, the self-metathesis
of butene to propene was investigated. Wang et al.
[2] reported the self-metathesis of butene to propene over
WO3/SiO2 and the dependency of butene metathesis on the
tungsten oxide species on the surface of the catalyst.
Mattheus et al. [7] have described a process for the pro-
duction of propylene by butene metathesis.
Introduction
Recently, it was found that tungsten oxide supported on
mesoporous silica exhibits excellent activity and selectivity
in metathesis for the butene without any co-catalyst [8].
Compared to conventional catalysts, catalysts based on
mesoporous silica, such as MCM-41 [9], HMS [10], and
MCM-48 [4], possess excellent activity since mesoporous
materials possess high surface area, and tunable uniform
channels ranging from 5 to 30 nm, which can accommo-
date more active species and transfer mass.
The metathesis of alkenes is a process with many technical
applications, such as, synthesis of propene and ethene [1, 2]
and of intermediates for surfactant synthesis [3]. To
achieve more of the desired products, catalysts for the
metathesis of alkenes have been extensively studied in
the past two decades [2–4]. In heterogeneous catalysis, the
most used catalysts for olefin metathesis are WO3 sup-
ported on alumina or silica carriers due to their long life-
time and high tolerance to impurities such as water and
The objective of this contribution is to utilize the
advantages of mesoporous molecular sieves (MTS-9) in
the preparation of supported tungsten oxide catalysts for
butene metathesis. The paper highlights the significant
effects of loading on the properties of the WO3/MTS-9
catalysts.
Electronic supplementary material The online version of this
article (doi:10.1007/s11243-010-9458-7) contains supplementary
material, which is available to authorized users.
D. Hua Á S.-L. Chen (&) Á G. Yuan Á Y. Wang Á L. Zhang
State Key Laboratory of Heavy Oil Processing,
College of Chemical Engineering, China University
of Petroleum, Beijing 102249, People’s Republic of China
e-mail: slchen@cup.edu.cn
Experimental
MTS-9 was hydrothermally synthesized in a two-step
procedure as given in the literature [11, 12]. First,
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Transition Met Chem (2011) 36:245–248
precursors containing titanosilicate (TS-1) nanoclusters
were prepared. Second, the preformed precursors were
assembled with triblock copolymers in a strong acid
medium (pH \ 1).
Preparation of the catalysts
Scheme 1 Possible reaction pathways of 2-butene
WO3/MTS-9 catalysts with different tungsten loadings
were prepared by a wet impregnation method with water
solutions of ammonium metatungstate. The WO3 to MTS-9
ratio (in weight) of the catalyst WO3/MTS-9 were 4.0, 8.0,
12.0, and 16.0 wt. %, respectively. The impregnated
products were dried at 353 K for 12 h; then, the catalysts
were thermally treated at 823 K for 4 h in a temperature-
programmed furnace (1 K/min).
products were analyzed using a gas chromatograph
equipped with a flame ionization detector and a 50-m
PONA capillary column.
Results and discussion
Physical and spectroscopic characterization
Catalyst characterization
Figure 1 shows the XRD spectra of WO3, SiO2 and WO3/
MTS-9 catalysts with different WO3 loadings. MTS-9
possesses almost the same diffraction pattern as SiO2
because the titanium is dispersed into the silica framework.
When the loading of WO3 is less than 8% (wt), the XRD
spectra are the same as that of the support, indicating the
absence of very small crystalline WO3 and well-dispersed
tungsten oxide species on the surface of the support. Above
8% WO3 loading, crystalline WO3 is observed in the XRD
spectra. The intensity of crystalline WO3 increases with
increasing WO3 loading, suggesting that the crystallite size
increases with increasing WO3 loadings.
X-ray powder diffraction patterns of the WO3/MTS-9
catalyst were recorded on a Bruker D8 ADVANCE dif-
˚
fractometer, using CuKa (1.5,406 A) radiation in the 2h
range of 108–608 with a scanning rate of 18/min. The UV–
Vis DRS (diffuse reflectance spectroscopy) of the catalyst
was recorded in the range of 200–800 nm against the
support as reference, on a Hitachi U-4100 spectropho-
tometer (Japan) equipped with an integration sphere diffuse
reflectance attachment. UV-Raman spectra were obtained
on a HR800UV-Raman spectrograph (Horiba Jobin–Yvon
Company, France). The 244.0 nm line from a He–Cd laser
was used as the excitation source. The spectrum resolution
Ultraviolet–visible diffuse reflectance spectroscopy is a
useful method to distinguish the structure of tungsten
species in catalysts [13]. The UV–Vis spectra for the
samples are shown in Fig. 2. The bands at 228, 287, and
400 nm have been assigned to distorted isolated surface
is estimated to be 4.0 cm-1
.
Catalytic tests
The catalytic activity of all the catalysts was tested in the
metathesis of butene. The metathesis reactions were carried
out in a downflow fixed-bed stainless steel microreactor
(10 mm i.d.), using 0.375 g of the catalyst. The C4 stream
was treated through BASF adsorbents Selexsorb CD and
COS for the removal of oxygenated organic compounds
and other trace contaminants that can cause catalyst
deactivation. Before the C4 stream was introduced into the
reactor, the catalyst was pretreated in situ with a N2 and H2
mixture flow for 30 min at 693 K. The weight hour space
WO3
16%WO /MTS-9
3
12%WO /MTS-9
3
velocity (WHSV) of the metathesis reaction was 6.4 h-1
.
8%WO3/MTS-9
4%WO3/MTS-9
MTS-9
Reactions of 2-butene over WO3/MTS-9 catalysts include
metathesis and isomerization of 2-butene; the main prod-
ucts of which are propene, pentene, ethene, hexene, and
1-butene. Propene and pentene are products of the cross-
metathesis of 1-butene and 2-butene. First, 2-butene iso-
merizes to 1-butene. Second, 2-butene and 1-butene dis-
proportionate to propene, which is the primary reaction.
Scheme 1 displays the reaction pathways in detail. All the
SiO
2
10
20
30
40
50
60
2θ
Fig. 1 XRD spectra of WO3/MTS-9 with different WO3 loadings
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Transition Met Chem (2011) 36:245–248
247
287
228
400
16%WO3/MTS-9
12%WO3/MTS-9
WO3
16%WO3/MTS-9
8%W0
4%W0
3 /MTS-9
12%WO3/MTS-9
8%WO3 /MTS-9
3 /MTS-9
4%WO3 /MTS-9
MTS-9
MTS-9
SiO2
200 250 300 350 400 450 500 550 600 650 700 750 800
Wavelength(nm)
Fig. 2 UV–vis diffuse reflectance spectra of various samples
200 400
600 800 1000 1200 1400 1600 1800 2000
Raman Shift(cm-1)
species, polytungstate monoxo surface species, and crystal
WO3, respectively. The diffraction peak at 228 nm is
assigned to the isolated titanium framework for MTS-9
[14–16]; the bands at 228 and 287 nm suggest that the
surface tungstate consists of distorted isolated WO4 dioxo
surface species (Raman band at *1,000 cm-1) and poly-
tungstate monoxo surface WO5/WO6 (Raman band at
*1,100 cm-1) that may have a distorted tetrahedral or an
octahedral coordination environment [17, 18]. The two
bands in the UV–vis spectra indicate that two distinct
surface tungstate species are present on the catalysts. For
loading above 8%, an additional peak is observed at
400 nm, and the intensity increases slightly with the
increase in WO3 loading, in accordance with the results
obtained by XRD. The intensity of the peaks at 228 and
287 nm increases slightly with the increase in WO3 load-
ing, and they may be active centers for the metathesis
reaction.
Fig. 3 The Raman spectra of SiO2 and catalysts with different
loadings
MTS-9 and SiO2 have common bands at *488, *790,
*976, and *1,090 cm-1, but the intensity of the band at
*1,090 cm-1 for MTS-9 is stronger than that for SiO2,
suggesting that these bands (*976 and *1,090 cm-1) can
be attributed to the resonance Raman effect [22]; the others
bands were characteristic of SiO2. For catalysts with dif-
ferent WO3 loadings, very strong bands at *1,000 and
*1,110 cm-1 are observed. In comparison with SiO2
and MTS-9, the bands at *976 and *1,090 cm-1 for SiO2
and MTS-9 shift to *1,000 and *1,110 cm-1 for catalysts
with different WO3 loadings. The intensities of the bands at
*1,000 and *1,110 cm-1 are stronger for the catalysts
than for MTS-9. The two bands of the catalysts at *1,000
and *1,110 cm-1 increase in intensity gradually from 4 to
12% loading, and the two bands for 16% loading is almost
the same for 12% loading. According to the literature [16,
23], the Raman band at *1,000 cm-1 is assigned to the
O=W=O group of the isolated surface tetrahedral tungsten
oxide species. The Raman band at *1,100 cm-1 corre-
sponds to a surface octahedral structure of polytungstate
with monoxo W=O coordinated species. For 4% WO3/
MTS-9, only the Raman bands at *1,000 and *1,100
cm-1 are observed, whereas additional Raman bands are
observed for the other catalysts. For 8% WO3/MTS-9, an
additional Raman band is observed at *800 cm-1; For 12
and 16% WO3/MTS-9, additional Raman bands are
observed at *270–320 cm-1 and *730–800 cm-1 due to
more crystalline WO3 particles. These four bands are
assigned to the W–O deformation, W–O stretching mode
The major structural information concerning the surface
tungsten oxide species on solid supports can be derived
from Raman spectroscopy because of its ability to distin-
guish different tungsten oxide species that may simulta-
neously be present in the catalysts. The Raman spectra of
SiO2, MTS-9, and WO3/MTS-9 with different WO3 load-
ings are shown in Fig. 3 Pure SiO2 exhibits Raman bands
at *1,090, *976, *792, *600, and *489 cm-1 [19].
Two silica network bands at 1,090 and 792 cm-1 are
assigned to the transverse-optical (TO) asymmetric stretch
and Si–O–Si symmetrical stretching [20]. The *976 cm-1
Raman band is assigned to the Si–OH stretching mode of
the surface hydroxyls [20, 21]. The vibrational bands at
*600 and *489 cm-1 are attributed to tri- and tetra-
cyclosiloxane rings, respectively [21]. MTS-9 also exhibits
Raman bands at *488, *797, *978, and 1,100 cm-1
.
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Transition Met Chem (2011) 36:245–248
40
30
20
10
0
loading amount of WO3 on MTS-9 is responsible for the
catalytic activity with 12% WO3 loading giving the best
results, and selectivity of products is independent of WO3
loading. On the basis of the characterization data and
results of the metathesis experiments, we conclude that
surface tungsten species, in the form of tetrahedral and/or
octahedral tungsten sites, are active centers rather than
crystalline WO3.
4W/MTS-9
8W/MTS-9
12W/MTS-9
16W/MTS-9
MTS-9
WO3
Acknowledgments This research work was supported by the SIN-
OPEC Jiujiang Petrochemical Company and the National Nature
Science Foundation of China (Grant No: 20976192).
References
0
10
20
30
40
50
1. Sheu F-C, Hong C-T, Hwang W-L, Shih C-J, Wu J-C, Yeh C-T
(1992) Catal Lett 14:297–304
Time on stream(h)
2. Wang Y, Chen Q, Yang W, Xie Z, Xu W, Huang D (2003) Appl
Catal A Gen 250:25–37
3. Spamer A, Dube TI, Moodley DJ, Schalkwyk C, Botha JM
(2003) Appl Catal A Gen 255:133–142
Fig. 4 Correlation of loadings and yield of propene. Reaction
condition: T = 320 °C, P = 0.8 MPa, WHSV = 6.4 h-1
[24, 25], indicating that high loadings of tungsten species
may result in the agglomeration of bulk microcrystalline
WO3 on the surface.
´
´
4. Topka P, Balcar H, Rathousky J, Zilkova N, Verpoort F, Cejka J
(2006) Microporous Mesoporous Mater 96:44–54
5. Huang S, Liu S, Xin W, Bai J, Xie S, Wang Q, Xu L, Mol J
(2005) Catal A Chem 226:61–68
6. Liu H, Huang S, Zhang L, Liu S, Xin W, Xu L (2009) Catal
Commun 10:544–548
Metathesis experiments
7. Mattheus BJ, Justice MMM, Simon NB, WO 00/14038
8. Hu J-C, Wang Y-D, Chen L-F, Richards R, Yang W-M, Liu Z-C,
Xu W (2006) Microporous Mesoporous Mater 93:158–163
Loading is an important factor that influences the perfor-
mance of catalysts. The properties of catalysts with dif-
ferent loadings were tested as a function of time on stream.
Figure 4 shows the effect of WO3 loading on yield of
propene, and the correlation between selectivity and load-
ing is shown in Suppl. Figs. 5–7. Figure 4 shows that plain
MTS-9 and tungsten trioxide catalysts are without
metathesis activity, the 4% WO3/MTS-9 which has no
WO3 crystallites on the basis of its of XRD, UV–DRS and
UV-Raman, and possesses metathesis activity. We specu-
lated that the metathesis centers are isolated surface tetra-
hedral and octahedral tungsten oxide species. In addition, it
can be seen from Fig. 4 that catalytic performance is
optimal for 12 wt% WO3/MTS-9. The activity decreases
with further increase in WO3 loading, perhaps because the
active centers are covered by an excess of crystalline WO3.
Suppl. Figs. 5–7 show that selectivity for propene, ethene,
and pentene is independent of loading.
´
´ ´
9. Balcar H, Zilkova N, Sedlacek J, Zednık J, Mol J (2005) Catal A
Chem 232:53–58
10. Ookoshi T, Onaka M (1998) Chem Commun (21):2399–2400
11. Mitra B, Gao X, Wachs IE, Hirtc AM, Deo G (2001) Phys Chem
Chem Phys 3:1144–1152
12. Xiao F-S, Han Y, Yu Y, Meng X, Yang M, Wu S (2002) J Am
Chem Soc 124:888–889
13. Lucas A, Valverde JL, Can˜izares P, Rodriguez L (1999) Appl
Catal A Gen 184:143–152
14. Barton DG, Shtein M, Wilson RD, Soled SL, Iglesia E (1999) J
Phys Chem B 103:630–640
15. Gazzoli D, Valigi M, Dragone R, Marucci A, Mattei G (1997) J
Phys Chem B 101:11129–11135
16. Ross-Medgaarden EI, Wachs IE (2007)
111:15089–15099
J Phys Chem C
17. Notari B (1996) Advanced materials in catalysis. Academic
Press, New York, pp 253–334
18. Grieneisen JL, Kessler H, Fache E, Legovic AM (2000) Micro-
porous Mesoporous Mater 37:379–386
19. Lee EL, Wachs IE (2007) J Phys Chem C 111:14410–14425
20. Galeener FL, Mikelsen JC (1981) Phys Rev B 23:5527–5530
21. Morrow BA, McFarlan AJ (1990) J Non-Cryst Solids 120:61–71
22. Li C, Xiong G, Xin Q, Liu JK, Ying PL, Feng ZC, Li J, Yang
WB, Wang YZ, Wang GR, Liu XY, Lin M, Wang XQ, Min EZ
(1999) Angew Chem Int Ed 38:2220–2222
Conclusion
23. Li C, Xiong G, Liu J, Ying P, Xin Q, Feng Z, Phys J (2001) Chem
B 105:2993–2997
24. Lee EL, Wachs IE (2008) J Phys Chem C 112:6487–6498
25. Anderson A (1976) Spectrosc Lett 9:809–819
We have developed an advanced heterogeneous olefin
metathesis catalyst, which is composed of tungsten oxide
supported silica-titanium (MTS-9). It was found that the
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