Shape-selective alkylation of biphenyl over H-[Al]-SSZ-24 zeolites with AFI topology

Article abstract of DOI:10.1246/bcsj.80.215

H-[Al]-SSZ-24 zeolites with AFI topology were synthesized through the alumination of [B]-SSZ-24 zeolites, and applied for the alkylation of biphenyl (BP). H-[Al]-SSZ-24 zeolites have high activity for the isopropylation. The shape-selective formation of 4,4′-diisopropylbiphenyl (4,40-DIPB) occurred at moderate temperature; however, the selectivity for 4,40-DIPB decreased with an increase in the reaction temperature. Isomerization of 4,4′-DIPB occurred at higher temperatures over internal and external acid sites when there are enough acid sites inside the channels. The channels can discriminate 4,4′-DIPB from the other DIPB isomers in their transition states; however, they can not prevent the isomerization of 4,4′-DIPB at higher temperatures. The selectivity for the least bulky 4,4′-dialkylbiphenyl increased with the bulkiness of alkylating agents in the order: isopropylation < s-butylation < t-butylation. These results strongly support the shape-selective formation of the least bulky products inside the channels of H-[Al]-SSZ-24 zeolites.

Full text of DOI:10.1246/bcsj.80.215

Ó 2007 The Chemical Society of Japan
Bull. Chem. Soc. Jpn. Vol. 80, No. 1, 215–223 (2007)
215
Shape-Selective Alkylation of Biphenyl over H-[Al]-SSZ-24
Zeolites with AFI Topology
Akira Ito, Hiroyoshi Maekawa, Hiroaki Kawagoe, Kenichi Komura,
y
ꢀ
Yoshihiro Kubota, and Yoshihiro Sugi
Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Gifu 501-1193
Received June 23, 2006; E-mail: ysugi@cc.gifu-u.ac.jp
H-[Al]-SSZ-24 zeolites with AFI topology were synthesized through the alumination of [B]-SSZ-24 zeolites, and
applied for the alkylation of biphenyl (BP). H-[Al]-SSZ-24 zeolites have high activity for the isopropylation. The shape-
0
0
selective formation of 4,4 -diisopropylbiphenyl (4,4 -DIPB) occurred at moderate temperature; however, the selectivity
0
0
for 4,4 -DIPB decreased with an increase in the reaction temperature. Isomerization of 4,4 -DIPB occurred at higher tem-
peratures over internal and external acid sites when there are enough acid sites inside the channels. The channels can
discriminate 4,4 -DIPB from the other DIPB isomers in their transition states; however, they can not prevent the isomer-
ization of 4,4 -DIPB at higher temperatures. The selectivity for the least bulky 4,4 -dialkylbiphenyl increased with the
bulkiness of alkylating agents in the order: isopropylation < s-butylation < t-butylation. These results strongly support
the shape-selective formation of the least bulky products inside the channels of H-[Al]-SSZ-24 zeolites.
0
0
0
Zeolites are the most promising microporous crystals for
achieving highly shape-selective catalysis because their pores
are uniformly distributed and have dimensions allowing both
organic reactants and products to enter, to accommodate, and
to leave. Large-pore molecular sieves (LPMS) are expected
to be useful as catalysts in the alkylation of polynuclear aro-
It is important to know how zeolite structure influences
shape-selective character of the alkylation of BP and how
the bulkiness of alkylating agent influences shape-selective
catalysis. These questions have led us to investigate the cata-
lytic properties of H-[Al]-SSZ-24 zeolites. In this paper, we
describe the isopropylation, s-butylation, and t-butylation of
BP over H-[Al]-SSZ-24 zeolites to elucidate the relationships
between their pore structure and shape-selective catalysis.
1
,2
3
–5
0
0
matics. 4,4 -Diisopropylbiphenyl (4,4 -DIPB) has been se-
lectively produced from biphenyl (BP) over dealuminated
H-mordenite (MOR).3 It is very interesting to elucidate the
catalytic features of LPMS pores in the catalysis; however,
there have been very few articles on the subject other than
MOR. Our previous relevant findings on the subjects have
been published on the alkylation of BP over H-[Al]-SSZ-
–9
Experimental
Synthesis of H-[Al]-SSZ-24 Zeolites. N(16)-Methylsparteini-
þ
ꢁ
um hydroxide ([MeSPA ]OH ) was synthesized by the quaterni-
zation of sparteine with methyl iodide, followed by ion-exchange
with ion-exchange resin. The detailed procedure is reported else-
where.20 [B]-SSZ-24 was hydrothermally synthesized from a gel
1
0
11
12
31, H-[Al]-CIT-5, SAPO-5, and MAPO-5 (M: Mg, Ca,
1
Sr, Ba, and Zn).
3–15
þ
ꢁ
having the composition 1.0SiO2–0.04B2O3–0.2[MeSPA ]OH –
0.1NaOH–50H2O.19 A typical procedure is as follows. After
stirring the mixture of a NaOH solution (32 wt %, 375 mg), a
H-[Al]-SSZ-24 zeolite is a high-silica large-pore molecular
sieve, which is isostructural with AlPO4-5 (AFI topology),
16
and is expected to work as a potential catalyst for shape-selec-
tive alkylation of polynuclear aromatics because of its straight
twelve-membered ring (12-MR) channel structure. SSZ-24
zeolite was first synthesized by Zones as its pure-silica form
using 1-trimethylammonioadamantane as a structure-directing
þ ꢁ ꢁ1
[
MeSPA ]OH solution (0.700 mmol g , 14.3 g), and sodium
borate decahydrate (Na2B4O7 10H2O, 381 mg) until the solution
ꢂ
became clear, and then, 3.00 g of fumed silica (Cab-O-Sil M-5,
Cabot) and 33.0 g of de-ionized water were added to the homo-
geneous mixture. A small amount (60 mg) of [B]-BEA seed was
added to the mixture, which was further stirred for 3 h. The mix-
ture was then transferred to a 23-mL Teflon-lined stainless auto-
1
7
agent (SDA). [B]-SSZ-24 zeolite in borosilicate version was
subsequently synthesized using a calcined form of boron-sub-
stituted zeolite beta ([B]-BEA) as the boron and silicon sour-
clave. The autoclave was kept statically in a convection oven at
ꢃ
1
8
ces. Lobo and Davis reported the synthesis of [B]-SSZ-24
þ
1
75 C for 5 days. The crystals were collected by filtration, wash-
zeolite using N(16)-methylsparteinium (MeSPA ) as SDA and
ed several times with de-ionized water, and dried overnight.
To remove the organic SDA occluded inside the [B]-SSZ-24
zeolite, the as-synthesized sample was kept in a muffle furnace,
using sodium borate as the source of boron.19 [B]-SSZ-24 zeo-
lite was easily converted to H-[Al]-SSZ-24 zeolites by post-
synthetic treatment with aluminum nitrate.19 This isomorphous
substitution will be expressed as ‘‘alumination’’ in this paper.
ꢁ1
and heated stepwise in a flow of air (100 mL min ). The temper-
ꢃ
ature was raised from room temperature to 650 C over a period of
3
10 min, and maintained at the same temperature for 4 h. Finally,
y Present address: Department of Materials Science and Engi-
neering, Graduate School of Engineering, Yokohama National
University, Yokohama 240-8501
the calcined sample was cooled to room temperature under ambi-
ent conditions.
[B]-SSZ-24 zeolite was aluminated to H-[Al]-SSZ-24 zeolites
Published on the web January 12, 2007; doi:10.1246/bcsj.80.215

2
16 Bull. Chem. Soc. Jpn. Vol. 80, No. 1 (2007)
Alkylation of Biphenyl over SSZ-24 Zeolites
Table 1. Properties of H-[Al]-SSZ-24 Zeolites
Surface area
ꢁ1
Pore volume
ꢁ1
h-Peak
ꢃ
Acid amount
ꢁ1
2
3
SiO2/B2O3
SiO2/Al2O3
/m g
/cm g
/ C
/mmol g
[
B]-SSZ-24
71
816
—
—
379
357
340
350
0.16
0.14
0.13
0.15
—
—
A1
A3
A5
768
172
135
243
278
269
0.024
0.165
0.175
—
ꢃ
ꢃ
by heating in an aluminum nitrate solution at 80 C for 18 h. The
relative weight of components in this alumination process was
zeolite:Al(NO3)3:H2O = 1:1:50, and this process was repeated
several times.
1 h, and ammonia was adsorbed at 100 C followed by further
evacuation for 1 h. Then, the sample was heated from 100 to
ꢃ
ꢃ
ꢁ1
710 C at a rate of 10 C min in a helium stream. TG analysis
was performed on a Shimadzu DTG-50 analyzer with tempera-
ꢃ
ꢁ1
Catalytic Reaction. The alkylation of BP was carried out in a
00-mL SUS-316 autoclave under a pressure of the alkylating
ture-programmed rate of 10 C min in an air stream. The solid
11B, 29Si, and 27Al NMR spectra were recorded at room tempera-
ture under magic-angle spinning (MAS) by using 7.0 mm diameter
zirconia rotor spinning at 4 kHz on an Inova 400 spectrometer
(Varian Corporation, MA, U.S.A.).
1
agent. Typical conditions of the isopropylation are: BP 50 mmol,
zeolite 0.25 g, propene pressure 0.8 MPa, reaction temperature
ꢃ
1
50–250 C, and reaction time 4 h. An autoclave containing BP
and the zeolite was purged with N2 before heating. After reaching
the reaction temperature, propene was introduced to the autoclave,
and the pressure kept constant throughout the reaction. After cool-
ing the autoclave, the zeolite was filtered off, and bulk products
were diluted with toluene. The products were analyzed by gas
chromatography (GC-14A, Shimadzu Corporation, Kyoto) equip-
ped with an Ultra-1 capillary column (25 m ꢄ 0:2 mm; Agilent
Technologies, MA, U.S.A.), and identified by using a Shimadzu
Gas Chromatograph-Mass Spectrometer GC-MS 5000. The yield
of each product was calculated on the basis of the amounts of
starting BP, and the selectivities for each IPBP and DIPB isomers
are expressed based on the total amounts of IPBP and DIPB iso-
mers, respectively.
Results and Discussion
Properties of H-[Al]-SSZ-24 Zeolites. [B]-SSZ-24 zeo-
20
lites were synthesized by the methods in the literature. Typi-
cal properties of the zeolites are shown in Table 1. [B]-SSZ-24
þ
ꢁ
zeolite was converted from [B]-BEA using (MeSPA )OH
as the SDA under hydrothermal conditions. [B]-SSZ-24 zeo-
lite had a SiO2/B2O3 ratio of 71, specific surface area (379
2
ꢁ1
2
ꢁ1
m g ), and pore volume (0.16 cm g ). H-[Al]-SSZ-24 zeo-
lites were obtained from [B]-SSZ-24 by repeating the alumina-
tion process as described in the Experimental Section.18 Sam-
ples aluminated for n times are abbreviated as An (n: 1–8).
Figure 1 shows the influences of the boron and aluminum con-
tents on the alumination. Boron content of [B]-SSZ-24 zeolite
decreased rapidly due to alumination; however, the aluminum
content gradually increased with each repetition. From these
samples, we chose samples, A1, A3, and A5 of which the
SiO2/Al2O3 ratios were 768, 172, and 135, respectively.
Figure 2 shows the XRD patterns of calcined [B]-SSZ-24
and H-[Al]-SSZ-24 zeolites A1, A3, and A5. Figure 3 shows
Selectivity for a DIPB (IPBP) isomer (%)
Each DIPB (IPBP) isomer (mol)
¼
ꢄ 100:
ð1Þ
DIPB (IPBP) isomers (mol)
The analysis of products encapsulated in the zeolite used for the
reaction was carried out as follows. The zeolite was filtered off,
ꢃ
washed well with 200 mL of acetone, and dried at 110 C for
2 h. The zeolite (100 mg) was carefully dissolved in 47% aque-
1
ous hydrofluoric acid (3 mL) at room temperature. The solution
was basified with solid potassium carbonate, and the organic layer
was extracted three times with 20 mL of dichloromethane with
ice-cooling. After removal of the solvent in vacuo, the residue
was dissolved in 5 mL of toluene, and 10 mg of naphthalene
was added as an internal standard. GC analysis was performed ac-
cording to the same procedure as that for bulk products. The en-
capsulated products were expressed by the selectivity because
quantitative analysis was difficult.
1
0
8
6
4
2
B/Si
Al/Si
A5
A3
A1
The s- and t-butylations of BP were carried out in a similar
manner as the isopropylation.
Characterization of Zeolites. The crystal structure of zeolites
was determined by powder X-ray diffraction using Shimadzu
XRD-6000 with Cu Kꢀ radiation (ꢁ ¼ 0:15418 nm). Elemental
analysis was performed by inductive coupled plasma atomic emis-
sion spectroscopy on a JICP-PS-1000 UV (Teledyne Leeman Labs
Inc., NH, U.S.A.). Crystal size and morphology were observed
by using an S-4300 FE-SEM microscope (Hitachi Corporation,
Tokyo). Nitrogen adsorption measurements were carried out on
a Belsorp 28SA (BEL Japan Inc., Osaka). Temperature-program-
med desorption of ammonia (NH3-TPD) was measured using a
S
A
C
1
2
3
4
5
6
7
8
Sample
Fig. 1. The isomorphous substitution of boron in [B]-SSZ-
24 zeolites with aluminum. Abbreviation: S: starting gel;
A: as-synthesized sample; C: calcined sample; Arabic nu-
merals: numbers 1–8 correspond to the sample A1–A8, re-
spectively as defined in the text. A1, A3, and A5 were used
for the catalysis.
ꢃ
Bel TPD-66 apparatus. The zeolite was evacuated at 400 C for

A. Ito et al.
Bull. Chem. Soc. Jpn. Vol. 80, No. 1 (2007)
217
SEM images of [B]-SSZ-24 and H-[Al]-SSZ-24 zeolites A1,
A3, and A5. These results show that the structures of H-[Al]-
SSZ-24 zeolites were retained during the alumination.
Figure 5 shows solid 11B, 27Al, and 29Si MAS NMR
spectra of H-[Al]-SSZ-24 zeolites during the alumination.
1
1
B MAS NMR spectra of as-synthesized [B]-SSZ-24 (not
shown) gave only a peak at ꢁ3:7 ppm corresponding to tetra-
NH3-TPD spectra of H-[Al]-SSZ-24 zeolites are shown in
Fig. 4. They have two types of desorption peak, so-called l-
hedral boron. Upon calcination, a minor broad peak assignable
21
ꢃ
and h-peaks, at 160–180 and 260–280 C, respectively. The
to trigonal boron appeared at around 6.1 ppm in addition to
h-peak is due to desorbed NH3 from Brønsted acidic sites,
which work in solid acid catalysis. On the other hand, the l-
peak is due to physisorbed NH3, which plays no important role
in solid acid catalysis. The acid amounts are 0.024, 0.165, and
an intense, sharp peak at ꢁ3:7 ppm. The signals of these boron
species almost disappeared after the first treatment with alumi-
num nitrate. The signals due to tetrahedral aluminum in the
Al MAS NMR spectra gradually developed during repeated
alumination over three repetitions. The spectra were taken in
2
7
ꢁ1
0
.175 mmol g
for A1, A3, and A5 zeolites, respectively.
These results show that the introduction of aluminum to nest
silanol groups, formed by the deboronation, was almost satu-
rated by the alumination for three times.
20
1
1
5
0
5
0
5
0
5
A5
A
A
5
A3
A1
1
1
Calcined
3
0
5
As synthesized
A1
0
2
10
20
30
40
50
50 100
200
300
400
500
2
θ/deg.
Temperature /°C
Fig. 2. XRD patterns of H-[Al]-SSZ-24 zeolites.
Fig. 4. NH3-TPD profiles of H-[Al]-SSZ-24 zeolites.
Calcined
A1
A3
A5
Fig. 3. SEM images of [B]-SSZ-24 and H-[Al]-SSZ-24 zeolites.

2
18 Bull. Chem. Soc. Jpn. Vol. 80, No. 1 (2007)
Alkylation of Biphenyl over SSZ-24 Zeolites
11B
27Al
29Si
3
Q4
Q +Si(1Al)
OSi
OSi
SiO Si OSi
OSi
SiO Si OH
OSi
tetrahedral
+
OSi
octahedral
SiO Si OAl
OSi
A5
A3
A5
A5
A3
*
*
A3
A1
A1
A1
*
*
OSi
SiO Si OB
OSi
tetrahedral
Si(1B)
trigonal
Calcined
Calcined
Calcined
1
00 80 60 40 20
0
-20 -40 -60 -80 -100 120 100 80 60 40 20
0
-20 -40 -60
0
-20 -40 -60 -80 -100 -120 -140 -160 -180 -200
ppm
Fig. 5. Solid 11B, 27Al, and 29Si MAS NMR spectra during the alumination of H-[Al]-SSZ-24 zeolites. shows spinning side band
peaks.
ꢀ
such a manner that the intensity reflects the amount. The major
tetrahedral peaks were accompanied by minor octahedral
peaks at an approximately constant ratio during the repeated
H-[Al]-SSZ-24 with relatively high amounts of acid such as
A3 and A5 zeolites can enhance the formation of bulky TriIPB
isomers. On the other hand, the formation of TriIPB isomers
was quite negligible over H-MOR. These differences may be
due to the slightly larger channels of H-[Al]-SSZ-24 zeolites
compared to H-MOR.
2
9
4
aluminations. Si MAS NMR spectra showed that the Q spe-
cies were predominant in all H-[Al]-SSZ-24 zeolites during
3
the aluminations. Almost no Q species was found in calcined
[B]-SSZ-24 zeolite; however, small but significant amounts of
The influence of SiO2/Al2O3 ratio of H-[Al]-SSZ-24 zeo-
3
0
the Q species appeared in A1 and A3 zeolites. These results
are consistent with the presence of residual silanol nests which
are caused by the almost complete deboronation of [B]-SSZ-24
lites on the catalytic activity and selectivity for 4,4 -DIPB
are shown in Fig. 7. The activities appeared at low tempera-
ꢃ
tures, such as 150 C over A3 and A5 zeolites, and the conver-
zeolite and a partial insertion of Al3 into framework.
The Isopropylation of BP over H-[Al]-SSZ-24 Zeolites.
Figure 6 shows the influence of reaction temperature on the
products composition in the isopropylation of BP over A1,
A3, and A5 zeolites. [B]-SSZ-24 zeolite had no activity to-
þ
sion reached 100% at 225–250 C. The selectivity for 4,4 -
ꢃ
ꢃ
0
DIPB was around 70% at 150–225 C, and it decreased with
an increase in reaction temperature. A similar change in activ-
ity and selectivity were observed over A1 zeolite, which has
very small amount of acid sites. The catalytic activity appeared
ꢃ
ꢃ
wards the isopropylation of BP at 250 C; however, the iso-
from 200 C, and increased with the increase in reaction tem-
0
morphous substitution of boron in [B]-SSZ-24 with aluminum
enhanced the catalytic activity for the isopropylation. Particu-
larly, A3 and A5 zeolites had very high activities affording
isopropylbiphenyl (IPBP), diisopropylbiphenyl (DIPB), and
triisopropylbiphenyl (TriIPB) isomers. These zeolites gave
perature. The selectivity for 4,4 -DIPB were around 75% at
ꢃ
temperatures lower than 300 C. The decrease in the selectivity
occurred with the further increase in temperature. These high
0
selectivities for 4,4 -DIPB in the level of 70–80% over A1,
0
A3, and A5 zeolites mean that the formation of 4,4 -DIPB oc-
curred inside the channels of H-[Al]-SSZ-24 zeolites, and that
ꢃ
TriIPB in large amounts even at 200 C. Catalytic activities
0
of A1 zeolite appeared at higher temperatures than those of
A3 and A5 zeolites. However, the profiles of the yield of IPBP,
DIPB, and TriIPB isomers over A1 zeolite versus reaction tem-
perature are quite resembled to A3 and A5 zeolites: the maxi-
mum yield of DIPB isomers over the A3 and A5 zeolites occur-
the channels can discriminate 4,4 -DIPB from other isomers in
the transition state. The difference in temperature for decreas-
ing the selectivity is due to the acid amount in the zeolites, and
not to the change of the pore structure of the zeolite.
The influences of reaction temperature on the selectivity for
DIPB over A3 and A1 zeolites, which have SiO2/Al2O3 ratio
of 172 and 768, respectively, are also shown in Figs. 8 and
ꢃ
red about 300 C higher than that of IPBP isomers of the A1
zeolite. These results show that the isopropylation of BP pro-
ceeds through the consecutive mechanism. i.e., BP to IPBP,
IPBP to DIPB, and DIPB to TriIPB, and that the channels of
0
9. The selectivities for 4,4 -DIPB of bulk products were around
70% for both A1 and A3 zeolites: at the lower temperatures

A. Ito et al.
Bull. Chem. Soc. Jpn. Vol. 80, No. 1 (2007)
219
Conversion & IPBP
DIPB
TriIPB
1
00
80
8
6
4
2
0
0
0
0
60
40
20
0
150 200 250 300 350 150 200 250 300 350 150 200 250 300 350
Reaction temperature /°C
Fig. 6. The influence of alumination on catalytic activity and the selectivity for isopropylates in the isopropylation of BP over
H-[Al]-SSZ-24 zeolites. Reaction conditions: zeolite (A1, A3, and A5), 0.25 g; BP, 50 mmol; propene, 0.8 MPa; temperature,
ꢃ
1
50–275 C; period, 4 h. Legends: conversion: , A1; , A3; , A5. IPBP, DIPB, and TriIPB: , A1; , A3; , A5.
1
00
100
80
60
40
20
0
100
80
60
40
20
0
100
80
60
40
20
0
Conversion
,4'-DIPB
8
6
4
2
0
0
0
0
0
4
3
3
,4'-DIPB
,3'-DIPB
150
200
250
300
350
150
175
200
225
250
275
Reaction temperature /°C
Reaction temperature /°C
Fig. 7. The influence of alumination on the selectivity for
Fig. 8. The influence of reaction temperature on the selec-
tivity for DIPB isomers in the isopropylation of BP over
H-[Al]-SSZ-24 zeolite. Reaction conditions: zeolite: A3,
0
4
2
,4 -DIPB in the isopropylation of BP over H-[Al]-SSZ-
4 zeolites. Reaction conditions: see Fig. 6. Legends: con-
0
version, , A1; , A3; , A5. selectivity for 4,4 -DIPB,
0
1
.25 g; BP, 50 mmol; propene, 0.8 MPa; temperature:
ꢃ
,
A1; , A3; , A5.
50–275 C; period, 4 h.
ꢃ
ꢃ
ꢃ
than 200 C for A3 zeolite, and lower than 300 C for A1 zeo-
peratures higher than 250 C. These results means that isomer-
0
0
lite. However, the selectivities of 4,4 -DIPB decreased with
increasing reaction temperatures over both zeolites, and the
ization of 4,4 -DIPB occurred over acid sites inside the chan-
nels and probably also at the external acid sites. On the other
0
0
selectivities for 3,4 -DIPB increased at higher temperatures.
ꢃ
hand, the selectivity for 4,4 -DIPB for A1 zeolite was as high
ꢃ
The decrease in the selectivity started at 225–250 C for the
ꢃ
as 70–80% even at higher temperatures, such as 300 C, al-
0
A3 zeolite, and at 300–325 C for the A1 zeolite. These results
though the selectivity for 4,4 -DIPB in bulk products decreased
ꢃ
0
suggest that H-[Al]-SSZ-24 zeolites have high shape-selectiv-
ity for the isopropylation of BP at moderate temperatures, al-
though it is lower than that of H-MOR as previously dis-
at 325 C. However, the selectivity for 4,4 -DIPB in encapsu-
ꢃ
lated products were remained almost constant even at 325 C.
0
Therefore, the decrease in the selectivity for 4,4 -DIPB in bulk
products over the A1 zeolite is due to the isomerization at ex-
ternal acid sites. Thus, acid sites inside the channels of A1 zeo-
3
–8
cussed. However, quite different features were observed in
0
the encapsulated products, i.e., the selectivity for 4,4 -DIPB
in encapsulated products for A3 zeolite was as high as those
0
lite did not work as the catalysts of isomerization of 4,4 -DIPB
because they have not enough amounts for the reaction. These
ꢃ
in bulk products below 250 C, and it decreased rapidly at tem-

2
20 Bull. Chem. Soc. Jpn. Vol. 80, No. 1 (2007)
Alkylation of Biphenyl over SSZ-24 Zeolites
1
00
100
80
60
40
20
0
The influence of reaction time on the selectivities for isopro-
ꢃ
Conversion
pylates in the isopropylation of BP over A3 zeolite at 175 C is
4
,4'-DIPB
shown in Fig. 10. The catalytic activity and the yield of isopro-
pylates in the bulk products during the catalysis are shown in
Fig. 10a. The yield of DIPB and TriIPB isomers increased
with a decrease in that of the IPBP isomers. These results sug-
gest the consecutive formation of isopropylates as discussed
above. However, the selectivities for isopropylates in the en-
capsulated products shown in Fig. 10b indicate that the selec-
tivities of isopropylates did not significantly vary during the
catalysis. The selectivities of DIPB isomers were almost con-
stant during the catalysis, and the selectivities for IPBP iso-
mers decreased slightly with an increase in that for TriIPB iso-
mers. These results show that the formation of DIPB and IPBP
isomers occurred inside the pores, and the products formed
inside the pores rapidly diffused out. The product distribution
of the encapsulated products shows that the catalysis steadily
occurs inside pores.
8
6
4
2
0
0
0
0
0
3
3
,4'-DIPB
,3'-DIPB
200
225
250
275
300
325
Reaction temperature /°C
Fig. 9. The influence of reaction temperature on the selec-
tivity for DIPB isomers in the isopropylation of BP over
H-[Al]-SSZ-24 zeolite. Reaction conditions: zeolite: A1,
Figure 11 shows the influences of reaction period on the se-
lectivities for IPBP and DIPB isomers in bulk and encapsulat-
ed products in the isopropylation of BP over A3 zeolite. The
influences of the selectivities for IPBP and DIPB isomers in
bulk products are shown in Fig. 11a. The selectivities for
0
1
.25 g; BP, 50 mmol; propene, 0.8 MPa; temperature:
ꢃ
50–275 C; period, 4 h.
0
0
0
results also show that the channels of SSZ-24 zeolite are large
0
4,4 -, 3,4 -, and 3,3 -DIPB were almost constant during the cat-
alysis; however, the selectivity for 4-IPBP decreased with an
increase in the selectivity for 3-IPBP. These results suggest
that 3-IPBP accumulated because of rapid consumption of
enough for the isomerization of 4,4 -DIPB and that the isomer-
0
ization of 4,4 -DIPB occurred both at the external and internal
acid sites although it depends on acid amounts. In contrast, no
0
0
isomerization of 4,4 -DIPB occurred at the internal acid sites
3
the highly reactive 4-IPBP, and that the formation of 4,4 -
DIPB occurred predominantly through 4-IPBP. These results
–5
over H-MOR.
These selectivities for 4,4 -DIPB of SSZ-24 zeolites are in
the similar level to those of SAPO-5 and MAPO-5 molecular
0
1–5
mean that ‘‘product selectivity’’ is operated in the catalysis.
0
Figure 11b shows the selectivities for 4,4 -DIPB and 4-IPBP
were almost constant in the encapsulated products during the
catalysis. These results suggest that the AFI channels can dis-
criminate the transition state of 4,4 -DIPB from those of the
other isomers resulting in the selective formation of the least
11,13–15
sieves with the AFI topology,
0
whereas the selectivity
4–8
for 4,4 -DIPB is lower than those for H-MOR. The differ-
0
0
ences in the selectivity for 4,4 -DIPB are due to the structural
difference between H-MOR and molecular sieves with AFI
topology.
0
bulky 4,4 -DIPB. It is worthy to note that the selectivity for
Bulk
Encapsulated
100
100
(
a)
(b)
8
6
4
2
0
0
0
0
0
80
60
40
20
0
0
5
10
15
0
5
10
15
20
Reaction time /h
Fig. 10. The influence of reaction time on the selectivity for isopropylates in the isopropylation of BP over H-[Al]-SSZ-24 zeolite.
(a) Conversion and yield of isopropylates in bulk products. (b) Composition of isopropylates in encapsulated products. Reaction
ꢃ
conditions: zeolite: A3, 0.25 g; BP, 50 mmol; propene: 0.8 MPa; temperature: 175 C. Legends: , conversion. , DIPB; , IPBP;
,
TriIPB.

A. Ito et al.
Bull. Chem. Soc. Jpn. Vol. 80, No. 1 (2007)
221
Bulk
Encapsulated
1
00
100
80
60
40
20
0
(
a)
(b)
8
6
4
2
0
0
0
0
0
0
5
10
15
0
5
10
15
20
Reaction time /h
Fig. 11. The influence of reaction time on the selectivity for IPBP and DIPB isomers in the isopropylation of BP over H-[Al]-SSZ-
24 zeolite. (a) Selectivity for IPBP and DIPB isomers in bulk products. (b) Selectivity for IPBP and DIPB isomers in encapsulated
products. Reaction conditions: see Fig. 10. Legends: DIPB isomers: , 4,4 -; , 3,4 -; , 3,3 -. IPBP isomers: , 4-; , 3-; , 2-.
0
0
0
Reaction
Reaction time (h)
Temperature (°C)
1
2
8
4
250
2
2
25
00
1
1
1
75
50
0
.5
1
20 200
300
400
500
600
700
1
20 200
300
400
500
600
700
Temperature /°C
Temperature /°C
Fig. 13. The influence of reaction time on TG profiles of
the zeolite used for the isopropylation of BP. Reaction
conditions: see Fig. 10.
Fig. 12. The influence of reaction temperature on TG pro-
files of the zeolite used for the isopropylation of BP. Re-
action conditions: see Fig. 8.
4
-IPBP among IPBP isomers was as high as 80% in the encap-
at higher temperature, and encapsulated products disappeared.
These results suggest that the channels of H-[Al]-SSZ-24 zeo-
lites were gradually choked by the coke-deposition, and organic
chemicals cannot come out of the channels by heating the zeo-
lites for TG measurements. Figure 13 shows the influences of
sulated products during the catalysis. These results mean that
the products rapidly diffuse inside the channels and that the
shape-selective catalysis steadily occurs. The less bulky 4-
IPBP can be accommodated easier than 3-IPBP inside chan-
nels, and thus, predominantly isopropylated to 4,4 -DIPB in-
side the channels. Similar exclusion of 3-IPBP was observed
during the isopropylation of BP over H-MOR.10
The TG profiles of the zeolites used for the reactions are
shown in Figs. 12 and 13. Figure 12 shows the influences of
reaction temperature over A3 zeolite. Coke appeared on the
0
ꢃ
reaction time on coke formation over A3 zeolite at 175 C.
Coke appeared just after the reaction started; however, the
amount of coke was almost constant during the catalysis. From
these results, coke formation inside the channels was not severe
towards the isopropylation of BP because acid sites are highly
dispersed in the zeolites. Similar results were also observed in
ꢃ
3–8
zeolite used for the reaction even at 150 C: the peaks at 200–
ꢃ
the isopropylation over highly dealuminated H-MOR.
The s- and t-Butylation of BP over H-[Al]-SSZ-24 Zeo-
lites. Figure 14 shows the influences of reaction temperature
3
5
00 C are assigned to encapsulated products and the peaks at
ꢃ
00–600 C to coke. The amounts of coke gradually increased

2
22 Bull. Chem. Soc. Jpn. Vol. 80, No. 1 (2007)
Alkylation of Biphenyl over SSZ-24 Zeolites
s-Butylation
t-Butylation
1
00
100
80
60
40
20
0
4
,4'-DTBB
8
6
4
2
0
0
0
0
0
4,4'-DSBB
Conv.
Conv.
3,4'-DSBB
3
,4'-DTBB
200
225
250
275
300
200
225
250
275
300
Temperature /°C
0
0
Fig. 14. The selectivity for 4,4 -di-s-butylbiphenyl and 4,4 -di-t-butylbiphenyl in the s- and t-butylations of BP. Reaction condi-
ꢃ
tions: zeolite, A3, 0.125 g; BP, 25 mmol; 1-butene or 2-methylpropene, 0.4 MPa; temperature, 200–300 C; period, 4 h.
0
on catalytic activity and the selectivity for 4,4 -di-s-butylbi-
CIT-5 zeolites of fourteen-membered pore with slightly corru-
gated channel. The differences in pore size reflect the lack
of discrimination among the transition states resulting in the
0
0
0
phenyl (4,4 -DSBB) and 4,4 -di-t-butylbiphenyl (4,4 -DTBB)
in the s- and t-butylations of BP over A3 zeolite. Although
the catalytic activities were low, s- and t-butylations of BP
0
lower selectivity for 4,4 -DIPB. These molecular sieves
have straight channel with similar pore entrance: 0:72 ꢄ 0:72
0
yielded selectively the least bulky products, 4,4 -DSBB and
0
16
22
4,4 -DTTB, and the selectivities in the butylations were higher
than those in the isopropylation. The difference in the selectiv-
nm for SAPO-5, 0:56 ꢄ 0:82 nm for H-[Al]-SSZ-31, and
16
0:72 ꢄ 0:75 nm for CIT-5.
0
0
ity for 4,4 -dialkylbiphenyl is due to the difference in steric
constraints of transition states inside the channels.
The selectivity for 4,4 -DIPB in encapsulated DIPB isomers
over H-[Al]-SSZ-24 zeolite was influenced by the SiO2/Al2O3
ratio, i.e. the amounts of acid sites. The selectivity decreased at
higher temperatures during the isopropylation of BP over the
zeolites with high acid amounts. In these zeolites, the isomer-
Shape-Selective Catalysis over H-[Al]-SSZ-24 Zeolites.
Catalytic performances of zeolites for the shape-selective cat-
alysis are generally influenced by many factors.1 Some of
typical factors on zeolites are pore structure, and physical
properties, such as crystal size, morphology, and density and
distribution of active species, which are also influenced by
preparation and post-synthesis methods. Reaction conditions,
such as temperature, pressure, period, and catalyst amount, al-
so influence the catalytic performances. Among these factors,
the pore structure is the most important for controlling the
shape-selectivity of the catalysis. The selectivity for the least
bulky isomer should be controlled by steric allowance of zeo-
lite pores for transition states to form each isomer.
,2
0
ization of 4,4 -DIPB occurs at internal acid sites because the
0
channels are large enough to allow the isomerization of 4,4 -
0
DIPB. However, the isomerization of 4,4 -DIPB did not occur
inside the channels of H-[Al]-SSZ-24 zeolites with high SiO2/
0
Al2O3 ratio, whereas a decrease in the selectivity for 4,4 -
DIPB in the bulk products was observed due to isomerization
at external acid sites. From these considerations, we can con-
clude that the internal and external acid sites of H-[Al]-SSZ-24
0
zeolites are active in the isomerization of 4,4 -DIPB resulting
0
in the decrease in the selectivity for 4,4 -DIPB in the isopropy-
0
The shape-selective formation of 4,4 -DIPB was observed
in the isopropylation of BP over H-[Al]-SSZ-24 zeolites,
which means that AFI channels can accommodate the transi-
lation of BP. These features over H-[Al]-SSZ-24 zeolites are
quite different from those of H-MOR: no isomerization occur-
red inside the pore of H-MOR because of the steric restric-
0
3–8
0
tion states for 4,4 -DIPB and discriminate among the transition
0
tion. A similar decrease in the selectivity for 4,4 -DIPB oc-
13–15
curred for MAPO-5 (M: Mg and Zn) with AFI topology.
states for the least bulky 4,4 -DIPB and the other isomers.
0
0
However, the selectivity for 4,4 -DIPB over H-[Al]-SSZ-24
However, no isomerization of 4,4 -DIPB was found in the en-
9
zeolites was lower than that of H-MOR. The difference in
the selectivity between the zeolites reflects the difference of
twelve-membered pore structures: 0:72 ꢄ 0:72 nm for H-[Al]-
SSZ-24 with straight channel and 0:67 ꢄ 0:72 nm for H-MOR
with straight channels with side pocket.16 The formation of
bulky DIPB isomers should occur inside the H-[Al]-SSZ-24
zeolite because their channels allow the bulky transition states
capsulated products for SAPO-5 although it has AFI topology.
This may be due to its weak acidity.23
There is another mechanism for the decrease in the selectiv-
0
ity for 4,4 -DIPB in the encapsulated products due to the
change of pore structure of H-[Al]-SSZ-24 zeolites. A fluctua-
tion in the channel width at higher temperatures could cause a
decrease in the steric restriction of the transition state to form
0
0
resulting in lower selectivity for 4,4 -DIPB. The selectivity for
0
4,4 -DIPB resulting the decrease in the shape-selective nature
of H-[Al]-SSZ-24 zeolites. However, this mechanism is not
4
3
,4 -DIPB was in the same level as those of SAPO-5 and SSZ-
1 zeolites of twelve-membered pore with straight channel and
0
probable because A1 zeolite had high selectivity for 4,4 -DIPB

A. Ito et al.
Bull. Chem. Soc. Jpn. Vol. 80, No. 1 (2007)
223
ꢃ
0
even at 300 C and because the isomerization of 4,4 -DIPB did
ꢃ
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H-[Al]-SSZ-24 zeolites with AFI topology were synthesized
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0
8
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H-[Al]-SSZ-24 zeolites gave lower selectivity for 4,4 -DIPB
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5
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0
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6
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0
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7
8
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