1) The Pt supported on mesoporous silicate FSM-16 showed high and stable catalytic activity for the hydrodesulfurization of thiophene at 350°C and this activity was higher than that of commercial CoMo/A120 3 catalysts. 2) Among noble metal/FSM-16 catalysts, Pt/FSM-16 showed the highest activity for the hydrodesulfurization of thiophene. The optimal loading of Pt on FSM-16 was determined to be 5 wt%. 3) The activity of Pt/FSM-16 decreased temporarily when hydrogen sulfide was introduced but was restored after cutting off the introduction, indicating that hydrogen sulfide is reversibly adsorbed on the Pt/FSM

1. i TDLS
CTYS
OAYI
AA
ELSEVIER Catalysis Today 39 (1997) 61-67
Noble metals supported on mesoporous silicate FSM-16
as new hydrodesulfurization catalyst
M. Sugioka*, L. Andalaluna, S. Morishita, T. Kurosaka
Department of Applied Chemistry, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050, Japan
Abstract
The Pt supported on mesoporous silicate FSM-16 showed high and stable catalytic activity for the hydrodesulfurization of
thiophene at 350°C and this activity was higher than that of commercial CoMo/A120 3 catalysts. The acid sites of FSM-16 and
the spillover hydrogen formed on Pt particle in Pt/FSM-16 catalyst play an important role for the hydrodesulfurization of
thiophene. © 1997 Elsevier Science B.V.
Keywords: Hydrodesulfurization; Mesoporous silicate; Pt/FSM-16 catalyst
1. Introduction contained in vacuum gas oil and heavy oil. Therefore,
the development of new catalysts based on large pore
CoMo/AI203 catalysts have been widely used in the zeolites to treat large molecular organic sulfur com-
hydrodesulfurization process of petroleum. However, pounds has been desired.
recently, the development of highly active hydrode- Recently, mesoporous silicate materials such as
sulfurization catalysts, which are better than commer- MCM-41 [11] and FSM-16 (folded-sheet mesoporous
cial CoMo/A1203 hydrodesulfurization catalysts, has material) [12,13] with large pore diameter have been
been claimed in the petroleum industry to produce developed. These new mesoporous silicate materials
lower sulfur content fuels. Such metal-zeolite cata- are attracting wide attention as catalysts and catalyst
lysts have high possibilities as a new hydrodesulfur- supports.
ization catalyst for petroleum [1-3]. We have In the present work, we examined the catalytic
investigated the hydrodesulfurization of thiophene activities of various noble metals supported on meso-
over transition metal Y zeolites (MeY) [4-7] and porous silicate FSM-16 for the hydrodesulfurization
noble metals supported on USY and HZSM-5 zeolites of thiophene in order to develop highly active meso-
[8-10]. These catalysts showed high catalytic activ- porous zeolite-based hydrodesulfurization catalysts.
ities for the hydrodesulfurization of thiophene. How-
ever, the pore diameter of these zeolites is too small for
treating large molecular organic sulfur compounds 2. Experimental
*Corresponding author. Tel.: 81-143-47-3338; fax: 81-143-47- Hydrodesulfurization of thiophene over noble
3129. metal/FSM-16 catalysts was carried out at 350°C
0920-5861/97/$32.00 © 1997 Elsevier Science B.V. All rights reserved.
PII S0920-5861 (97)00088-6

2. 62 M. Sugioka et al./ Catalysis Today 39 (1997) 61-67
under 1 atm by using a conventional fixed bed flow
reactor. Thiophene was introduced into the reactor by = . - - ~ PVFSM-16 •
passing hydrogen through a thiophene trap cooled at
0°C. The reaction products were analyzed by a gas- '2 ..................................._..~...~q._..~?./~
chromatograph.
l SO • Pd/FSM~I6 •
FSM-16-supported noble metal catalysts were pre- 40
pared by an impregnation method using noble metal 30 " - P~SH-16
chloride aqueous solutions; the amount of metal load-
10 Ir/FSM-~ 6
ing was 5 wt%. All catalysts were calcined at 500°C 0
for 4 h in air and were reduced at 450°C for 1 h prior to 0 1 2 3 4 5
Time on stream[hr]
the reaction. Presulfiding treatment of the catalysts
W/F-37,90. hr/mol Hz/TIliophene=30
was performed by 5% H2S-H2 mixture at 400°C for
1 h. XRD analysis of the catalysts was carried out by Fig. 1. Hydrodesulfurization thiopheneover noble metal/FSM-
of
using Rigaku diffractometer with Cu K~t radiation. 16 catalystsat 350°C.
We used mesoporous silicate FSM-16 (surface area
970 m2/g, channel diameter 27 ,~) which was provided
by Toyota Central R&D Labs., Japan.
time and Pd/FSM-16 and Rh/FSM-16 catalysts
showed lower steady state activity than CoMo/
3. Results and discussion A1203 catalyst. Among noble metal/FSM-16 catalysts,
Pt/FSM-16 showed the highest activity for the hydro-
3.1. Catalytic activities o f noble metals supported desulfurization of thiophene and the activity of Pt/
on FSM-16 FSM-16 catalyst was higher than that of CoMo/A1203
catalyst. Pt/FSM-16 catalyst also showed higher activ-
The catalytic activities of transition metals sup- ity than that of Pt supported on silica gel (SiO2) in the
ported on FSM-16 were examined at 350°C for the hydrodesulfurization of thiophene. The high and
hydrodesulfurization of thiophene. It was found that stable activity of Pt/FSM-16 catalyst in the hydrode-
the catalytic activities of transition metals/FSM-16 sulfurization of thiophene was kept even after it had
such as Ni/FSM-16, Co/FSM-16, Fe/FSM-16, W/ reacted for 20 h.
FSM-16, Mo/FSM-16 (5wt% loading), 15wt% Table 1 summarizes the activities of various cata-
MoO3/FSM-16, 5 wt% NiO-15 wt% MoO3/FSM-16 lysts used in this work.
and 5 wt% COO-15 wt% MoO3/FSM-16 showed low As PffFSM-16 showed the highest catalytic activity
activity and their activity values were lower than that in the hydrodesulfurization of thiophene at 350°C, we
of commercial CoMo/A1203 catalyst. Then we exam- studied in detail the catalyst performance and the
ined the catalytic activities of noble metals supported reaction mechanism in the hydrodesulfurization of
on FSM-16. Fig. 1 shows the hydrodesulfurization of thiophene over Pt/FSM-16 catalyst. It was found that
thiophene over various noble metal/FSM-16 catalysts the catalytic activity of Pt/FSM-16 was decreased
at 350°C. It was found that the catalytic activities of slightly by the presulfiding with H2S-H2 mixture as
noble metal/FSM-16 varied remarkably with the kind shown in Table 1. Thus, we used the Pt/FSM-16
of noble metals. The order of the activities of these catalyst without presulfiding.
catalysts for the hydrodesulfurization of thiophene In the hydrodesulfurization of thiophene over Pt/
after 2 h reaction was as follows: Pt/FSM-16>Pd/ FSM-16 catalyst, main reaction products were C4
FSM-16>Rh/FSM-16>>Ru/FSM-16, Ir/FSM-16, Au/ hydrocarbons (butane 88%, butenes 12%); trace
FSM-16. amount of C1-C3 hydrocarbons was also formed.
The initial activities of Pt/FSM-16, Pd/FSM-16 and These results indicate that Pt/FSM-16 catalyst has
Rh/FSM-16 were higher than that of commercial high hydrogenating ability for unsaturated Ca hydro-
CoMo/A1203 catalyst (dotted line). However, the carbons and low hydrocracking activity for hydrocar-
activities of these catalysts decreased with the reaction bons in the presence of hydrogen sulfide.

3. M. Sugioka et al./Catalysis Today 39 (1997) 61~7 63
Table 1 that of C o M o / A 1 2 0 3 catalyst for the reaction tempera-
Catalytic activities of various metals supported on FSM-16 in the ture above 320°C. The low activity of Pt/FSM-16
hydrodesulfurization of thiophene at 350°C (W/F-37.9 g h/mol,
H2/Thiophene=30)
catalyst below 320°C might be attributed to the sig-
nificant resistance of reactant diffusion into the chan-
Catalyst Conversion ( % ) a nel of FSM-16. That is to say, the comparable size of
Reduced Sulfided Pt particles to the p o r e d i a m e t e r o f F S M - 1 6 w o u l d b e
Catalystb Catalystc f o r m e d in the c h a n n e l o f F S M - 16 after the r e d u c t i o n o f
5 wt% Ni/FSM-16 2 Trace P t / F S M - 1 6 b y h y d r o g e n [14] a n d Pt p a r t i c l e s f o r m e d
5 wt% Co/FSM-16 2 9 i n h i b i t the d i f f u s i o n o f t h i o p h e n e into the c h a n n e l o f
5 wt% Fe/FSM-16 Trace Trace F S M - 1 6 at the r e a c t i o n t e m p e r a t u r e b e l o w 320°C.
5 wt% W/FSM-16 Trace 1
5 wt% Mo/FSM-16 15 19
15 wt% MoO3/FSM-16 39 22 3.2. Improvement of catalytic activity of Pt/FSM-16
5 wt% NiO-15 wt% MoO3/FSM-16 22 35
5 wt% COO-15 wt% MoOa/FSM-16 30 32 Results showed that 5 wt% Pt/FSM-16 calcined at
5 wt% Ru/FSM- 16 1 Trace 500°C had the highest catalytic activity for the hydro-
5 wt% Au/FSM-16 1 Trace desulfurization of thiophene. However, it is uncertain
5 wt% Ir/FSM-16 9 9 whether these preparation conditions are optimal or
5 wt% Rh/FSM-16 32 31 not. Therefore, we examined the effect of preparation
5 wt% Pd/FSM-16 56 62
5 wt% Pt/FSM-16 90 82 conditions on the catalytic activity of Pt/FSM-16 in
order to obtain the optimal activity of Pt/FSM-16
5 wt% Pt/SiO2 (JRC-SIO-1) 51 --
catalyst for the hydrodesulfurization of thiophene.
Commercial CoMo/A1203 -- 60
Fig. 3 shows the effect of Pt loading on the activity
aReaction after 2 h. of Pt/FSM-16 catalyst. The catalytic activity increased
bCatalysts were reduced at 450°C for 1 h °
with the increase of Pt loadings up to about 3.5 wt%
CCatalysts were sulfided at 400°C for 1 h after reduced at 450°C.
and the activity became constant for loading above
3.5 wt%. Thus, it can be concluded that 5 wt% loading
of Pt on Pt/FSM-16 is enough for obtaining the
100
maximum activity.
,o
Pt/FSM-16
~'~
"~ 50
Go
80
70
/ / ' l ~ l / f i '•~ " """"~"
coMo~
"
" "~
100
90
~ 40
80
30
70
60
10
8
5o
0 , , i i i i
200 220 240 260 280 300 320 340 360 380 400
Reaction temperature['C]
3O
Fig. 2. Comparison of catalytic activity of Pt/FSM-16 with that of 20
commercial CoMo/A1203 catalyst in the hydrodesulfurization of
10
thiophene.
1 2 3 4 5 6
Fig. 2 shows the comparison of the activity of FSM- Pt loading[w1%]
16 catalyst with CoMo/Al203 catalyst. It was found Fig. 3. Relationship between Pt loading and the catalytic activity
that the catalytic activity of Pt/FSM-16 is higher than of Pt/FSM-16 in the hydrodesulfurization of thiophene at 350°C.

4. 64 M. Sugioka et al./ Catalysis Today 39 (1997) 61-67
lOO lOO
90
80
80
70
70
Z 6o
9[ 6o
i'
ii
•~ 50
3O
20
I~-Ir Pt-Pd P~-Rh PI-Ru 25'~1%PI,FSM-165wI%Pt/FSM-16
10
0 i , t i Fig. 5. Catalytic activity of Pt (2.5 wt%) combined with other
200 300 400 500 600 700 800 noble metals (2.5 wt%) supported on FSM-16 in the hydrodesul-
Calcination temperature ['C] furization at 350°C.
Fig. 4. Effect of calcination temperature of Pt/FSM-16 on the
catalytic activity in the hydrodesulfurization of thiophene at 350°C.
to learn more about the origin of high and stable
activity of Pt/FSM-16 catalyst. The introduction of
hydrogen sulfide (3 ml/min) was performed using a
Fig. 4 shows the effect of calcination temperature microfeeder with a glass syringe; the concentration of
on the catalytic activity of Pt/FSM-16. The catalytic hydrogen sulfide in the hydrogen stream was ca.
activity of Pt/FSM-16 increased slightly up to the 5 vol%. The catalytic activity of Pt/FSM-16 was
calcination temperature at 500°C and it decreased remarkably decreased by the introduction of hydrogen
above 500°C. It was found that the calcination of sulfide in the course of hydrodesulfurization reaction.
the catalyst at 500°C is the optimal condition. However, the decreased activity was almost restored
In the previous paper [10], we showed that the after cutting off the introduction of hydrogen sulfide as
steady state activity of Pt/USY catalyst in the hydro- shown in Fig. 6. This shows that hydrogen sulfide is
desulfurization of thiophene was remarkably reversibly adsorbed on Pt/FSM-16.
improved by the combination with other noble metals. Furthermore, the activity of Pt/FSM-16 catalysts
Combination of Pt with Pd was the most effective. was slightly decreased after the presulfiding with 5%
Thus, we tried to enhance the steady state activity of H2S-H2 mixture at 400°C as shown in Fig. 6. These
Pt/FSM-16 by combining Pt (2.5 wt%) with other results indicate that the Pt/FSM-16 catalyst has high
noble metals (2.5 wt%). It was found that the steady
state activity of Pt/FSM-16 was not improved by the
combination of Pt with other noble metals and the
activity of 2.5 wt% Pt/FSM-16 was decreased by the 1oo
90
addition of 2.5 wt% other noble metals except Pd as
80
shown in Fig. 5.
70
3.3. Properties of Pt/FSM-16 catalyst 5O
agt,i ~ )
4O
Pt/FSM-16 catalyst showed high and stable activity 3O
for the hydrodesulfurization of thiophene among the 2O
10
noble metals supported on FSM-16. We also studied in
0
more detail concerning the catalytic properties of Pt/ 2 3 6
Time on stream [hr]
FSM-16 in the hydrodesulfurization of thiophene.
The effect of introduction of hydrogen sulfide on the Fig. 6. Reversible inhibition of hydrogen sulfide in the hydro-
catalytic activity of Pt/FSM-16 was examined in order desulfurization of thiophene at 350°C.

5. M. Sugioka et al./Catalysis Today39 (1997) 61-67 65
sulfur tolerant properties for the hydrodesulfurization
of thiophene as well as Pt/HZSM-5 catalyst described
in the previous paper [9].
On the other hand, as mentioned in the previous
papers [7-9], the acid site, especially Br~nsted acid
site, of H-zeolites (HY, USY, HZSM-5) as support in
5wt~/FSM-16
noble metal/H-zeolite catalysts plays an important
role for the hydrodesulfurization of thiophene. In this
5wt~Pt/FSM-~6
study, we examined the effect of introduction of
ammonia on the catalytic activity of Pt/FSM-16 in FS~I 6
the hydrodesulfurization of thiophene in order to ,0 20 30 ,'0 5'o ,; ,; 8; --
clarify the role of acidic properties of Pt/FSM-16 in Ze/degree
the hydrodesulfurization of thiophene. The introduc- Fig. 8. XRD patterns for various noble metal/FSM-16 catalysts
tion of ammonia (3 ml/min) was carried out using before reduction.
microfeeder with glass syringe as well as the intro-
duction of hydrogen sulfide. It was revealed that the
catalytic activity of Pt/FSM-16 was decreased by the 3.4. XRD analysis of Pt/FSM-16 catalyst
introduction of ammonia (ca. 5 vol%) in the course of
hydrodesulfurization reaction and decreased activity Fig. 8 shows the XRD patterns of FSM-16 and
was completely regenerated after cutting off the intro- noble metal/FSM-16 before reduction. Almost the
duction of ammonia as shown in Fig. 7. The catalytic same XRD patterns as that of FSM-16 were obtained
activity of PffFSM-16 was remarkably decreased by before and after loading of noble metals. This indi-
the addition of small amount (1 wt%) of sodium using cates that the structure of FSM-16 was maintained
sodium hydroxide aqueous solution to Pt/FSM-16 after loading of noble metals on FSM-16. No peaks
catalyst. Furthermore, FSM-16 also showed the cata- of Rh were observed on Rh/FSM-16 catalyst. On
lytic activities for the isomerization of 1-butene the other hand, broad and sharp peaks of Pd and Pt
(25 °C) and cyclopropane (150°C) and the dehydration were observed in the XRD analysis of Pd/FSM-16
of 2-propanol (250°C), which are typical acid-cata- and Pt/FSM-16 catalysts. The same XRD pattern
lyzed reactions. These results indicate that the acid of Pt/FSM-16 was observed for PtJFSM-16 after
sites exist on Pt/FSM-16 catalysts and the acid sites reduction at 450°C. These results infer that Rh is
play an important role for the hydrodesulfurization of loaded on FSM-16 with high dispersion but Pd
thiophene over Pt/FSM-16 catalyst. and Pt are loaded on FSM-16 with relatively large
particle size. The order of the dispersion of noble
metals on FSM-16 is assumed to be Rh/FSM-16>Pd/
FSM-16>Pt/FSM-16. This order is reverse to that
IO0 of the steady state activity of noble metal/FSM-16
90
catalysts in the hydrodesulfurization of thiophene. It is
80
interesting that the lower dispersion of noble metals
7O
.~ 60
on FSM-16, especially Pt/FSM-16, showed higher
Nm
~ 5O
int~ i catalytic activity for the hydrodesulfurization of
40 thiophene.
30
20
3.5. Mechanism of hydrodesulfurization of
10
thiophene on Pt/FSM-16 catalyst
0
3
qqmeoll stream [hr]
Pt/FSM-16 showed higher catalytic activity than
Fig. 7. Effect of introduction of ammoniaon the catalytic activity commercial CoMo/A1203 catalyst in the hydro-
of Pt/FSM-16 in the hydrodesulfurizatrionof thiophene at 350°C. desulfurization of thiophene. We also studied the

6. 66 M. Sugioka et al.ICatalysis Today 39 (1997) 61-67
mechanism of hydrodesulfurization of thiophene H2
over Pt/FSM-16 catalyst. As mentioned above, the HzS + C4 H y d r o c a r b o n ~ ' ~ /
acid site of FSM-16 in Pt/FSM-16 catalyst plays
an important role for the hydrodesulfurization of
thiophene. That is, it is assumed that the acid site
of FSM-16 in the Pt/FSM-16 catalyst acts as active
sites for the activation of thiophene, whereas Pt
IT Spillover
particles on FSM-16 act as active sites for the activa-
tion of hydrogen in the hydrodesulfurization of
thiophene. Furthermore, we supposed the existence
of spillover hydrogen in the hydrodesulfurization of Scheme 1. The possible mechanism of thiophenehydrodesulfur-
ization over Pt/FSM-16catalyst.
thiophene over Pt/FSM-16 catalyst. Hence, we tried to
confirm the existence of spillover hydrogen in the
hydrodesulfurization of thiophene. The catalytic mesoporous zeolite-based hydrodesulfurization cata-
activity of Pt/SiO2 (quartz) mixed mechanically lyst for petroleum feedstocks.
with FSM-16 was examined. It was found that the
activity of mixed catalyst obtained experimentally was
higher than that of the calculated one (A+B) as shown 4. Conclusion
in Fig. 9.
This suggests that there exists spillover hydrogen on It was found that the Pt/FSM-16 catalyst showed
Pt/FSM-16 in the hydrodesulfurization of thiophene. high and stable activity for the hydrodesulfurization of
Therefore, we propose a possible mechanism for the thiophene, Therefore, it is concluded that Pt/FSM-16
hydrodesulfurization of thiophene over Pt/FSM-16 might be a promising new hydrodesulfurization cata-
catalyst as shown in Scheme 1. In the proposed lyst for the petroleum feedstocks.
mechanism, thiophene is activated on the acid site
of FSM-16 and hydrogen is activated on Pt to form
spillover hydrogen. The spillover hydrogen formed on Acknowledgements
Pt particle attacks the activated thiophene formed on
the acid site on FSM-16. This work was partly supported by a grant-in-aid
On the basis of the proposed mechanism, it would from Ministry of Education, Science and Culture,
be possible to develop much more highly active Japan (082322060, 09650854) and the Petroleum
Energy Center of Japan. The authors thank Toyota
Central R&D Labs., Japan, for kind provision of FSM-
16 and also thank Dr. Yoshiaki Fukushima and Mr.
Shinji Inagaki of Toyota Central R&D Labs., Japan,
35
(A) {0.1g) + S ~ (B) (0.1g) for their valuable comments.
30
Z5
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