- Email: [email protected]
Preparation of superacids by metal oxides and their catalytic action
Materials Chemistry and Physics, 26 (1990) 213-237
213
REVIEW
PREPARATION
K.
OF SUPERACIDS
BY METAL OXIDES AND THEIR CATALYTIC
ACTION
iwATA*
Department
Hokkaido
of Science, Hakodate
Hachiman-cho,
University
of Education,
040 (Japan)
M. HINO Hakodate
Technical
College,
Tokura-cho,
Hakodate
042 (Japan)
ABSTRACT Our recent works on syntheses tungsten
or molybdenum
are reviewed. obtained
oxide
A1203
by adsorbing
is prepared
Superacids Ho(-14.52
sulfate
supporting
on zirconia,
ion onto hydroxides
from the crystallized
synthesized
themselves
are satisfactorily
which are generally discussed
catalyzed
and on their catalytic of up to Ho(-16.04
or amorphous
oxides of Fe, Ti,
with an acid strength
of
of up to
as that of the sulfate
Surface areas of the superacids
active
sulfate,
tungsten
in a heterogeneous
by strong acid.
on the basis of the results
action are
in air above 5OO'C; a superacid
in the same manner
Zr02 with W03 or Mo03.
oxides and
oxide.
with those of the oxides without
The superacids
sulfate-metal
with an acid strength
by calcination
by metal oxides
are
compared
supported
Solid superacids
Zr, Hf, Sn, and Si followed
of solid superacids,
Structure
superacid
by
are much larger
or molybdenum
oxide.
system for reactions
of acid sites is
of XPS, IR, and XRD spectra.
INTRODUCTION Following acidity
Gillespie's
is stronger
superacidity by mixing
has been reached
Lewis acid
such superacids
articles
arises
applications
Brijnsted acid
(BF3, SbF5,
TaF5,
etc.).
Ho&-12
superacid [l, 21.
when its Such a
which are generally
(HF. HS03F. CF3S03H. The interest
made up
etc.) and a
which has grown in
from the new areas which have been opened as well in as in the hydrocarbon
have been recently
025#584190/$3.50
any acid may be termed
by a number of systems
a flu'orine containing
fluorinated
synthetic
definition
than that of 100% H2S04, i.e.,
reviewed
by Olah
chemistry
field.
The research
[3, 43.
0 Etsevier Sequoia/Printed
in The ~etherIands
214 Solid acids have been extensively carriers
in chemical
industry
acids,
catalysts
oxides
of Si02-A1203,
Si02-Al203 organic
with high surface
bears
reactions.
The preparation
gasoline,
acids.
reactor
of homogeneous
in particular
and has been applied
of Si02-Al203
alkylation, advantages
and reutilization solid catalysts
are active areas
acylation,
methanol
of solid catalysts,
continuous
of the catalyst.
for disposal
and zeolites
as solid superacids.
operation,
Furthermore,
the
no corrosion
stronger
have been developed
The search
our recent works on syntheses
sulfate-supported
metal
as well
of the
of used catalyst.
solid acid systems
chemistry,
solid
solid acids as
to bring about an ease of
which allows
can lead to other advantages, problem
to
recent
of stronger
for solid superacids
of solid superacids
oxides and tungsten
than acidic
recently
and are
has become
since the early 197Os, and it is now the age of superacid.
action:
to various
has been determined
and characterization
is expected
mixture,
such as silica-alumina
summarizes
of solid
are the binary
liquid acids by heterogeneous
industry
and no environmental
categorized active
cracking,
of the reported
In the field of catalysis oxides
than Ho=-8.2
and Si02-Zr02;
acid strength
on the preparation
from the reaction
heterogeneous
stronger
and use of strong solid acids and superacids
in the chemical
as regeneration
or catalyst
Among a large number
[51, whose value is in the range of superacidity.
Because
Replacement
separation
acidity
Si02-Ti02,
The highest
has focused
catalysts
Ti02-Zr02,
for isomerization,
etc.
research
and used as catalysts
strong acid sites on the surface
so far to be Ho+-12
of research
studied
for many years.
This review
and their catalytic
or molybdenum
oxide supported
on zirconia.
SUPERACIDS
OF SULFATE-METAL
Benzylation Friedel-Crafts
of toluene alkylation,
and iron sulfates The activities activity
showed an unexpected
7OO'C have the following decompose proceeds
with calcination
at 700°C
calcined
properties:
rapidly,
temperature,
Preparation
of
[6-81. the maximum
[9-111.
at various
temperatures
that iron sulfates (1) The sulfates
and (2) the slight amount of sulfur of the sulfate
example
and sulfates,
for the reaction
to form CI-Fe203 at 675 to 7OO"C, and afterwards
the decomposition
salts exists mainly
were examined
heat-treated
at
completely
the crystallization
(0.15 wt%) remaining
after
as S042- on the surface.
of S04/Fe203
On the basis of the above results treated
is a typical
on calcination
It was concluded surface
which
over several metal oxides
effectiveness
dependent
of FeS04 and Fe2(S04)3
by XPS and XRD [12, 131.
chloride,
was performed
were remarkably
being observed
Surfaces
OXIDES with benzyl
at 700°C, sulfate-treated
for the surface
properties
ion oxides were differently
of iron sulfates
prepared,
and the
215 catalytic
effect
of sulfate
found that remarkable activity
of Fe203 result
treatment
in the surface
from the sulfate
(Fe203-I) Ltd.)
Works,
was prepared
ammonium
sulfate
and calcined
0.25-0.5
M H2S04 showed unexpectedly
2-propanol,
in air at 500-550°C.
Fe(OHj3.
treated
by heat-
After drying,
high activities
with ammonium
ion
2-propanol
activities
The maximum
for the sample
former activity
activity
sulfate acid.
of the sulfate
of the Fe203-I
are shown as a function
Fig. 1 1161.
were
the materials treated
for the reaction
with
of
catalyst
of calcination was observed
treated with sulfuric
was due to the catalytic
action
latter one was based on acid sites created
at 550-75O'C;
for the reaction
temperature
this
of
of the catalyst
in
at 300 and
It is considered
by the mounted
by strong
the
to form SO3.
with cafcination acid.
prepared
also enhanced
TGA data of the
showed a weight decrease
was caused by decomposition
The catalytic
(Kokusan
acid or aqueous
did not occur at all over the catalysts
The treatment
with sulfate
sulfuric
The Fe203 catalysts
to the same extent as that with sulfuric
catalysts
450-5OO'C
followed
Iron hydroxides
to aqueous
(30 ml) on a filter paper.
though the reaction
by calcining
decrease
and in the catalytic
ion treatment
as follows.
(2 g) were exposed
powdered
activity
It was
was examined.
acidity
[14, 151.
The catalyst Chemical
ion on solid acid catalysts
increases
that the
acid, but the
interaction
of the ion with
60
0 200
300
400
500
600
Co~cinotion temperature, "C Fig. 1. Reaction of 2-propanol to propylene over Fe203-I treated with 0.5 M H2S04 (@ 1 or (NH4)2S04 ( 0) and calcined at various temperatures. Pulse reaction conditions: He carrier 30 cm/min, pulse size 0.4 Ul (liquid), catalyst 30 mg, temperature 17O'C.
216 the support. maximum
In the case of the sample treated
activity
temperatures reasonable
below judging
The material adsorption
with ealcination
treated
with sulfate
sulfate
shown in Fig. 2 [15, 171. activity,
sulfate,
the at
seem to be
of ammonium
ion of 0.5 M concentration
sulfate
showed
itself.
IR
1120, and 1220 cm -1 , which are assigned
1030-1060,
coordinated
The results
ineffectiveness
to metal elements,
1.5 and 3 M showed the IR spectra
catalytic
with ammonium
at 500°C, and the calcination
300°C did not give activity. from the catalytic
bands at 980-990,
to the bidentate with
was observed
quite similar
The treatments
while the samples
treated
to those of iron sulfate
with S02, H2S and SO3 also promoted
the IR spectra of those
substances
being similar
as the
to (n) or
(E) in Fig. 2 115, 161. The Fe203-II subjected
than the Fe203-I
I prepared by hydrolyzing
catalyst
to the similar
treatment
showed higher
The quantity
catalyst.
Fe(N03)3 activity
of S was estimated
to be 0.92 and 0.23 wt% for the Fe203-II
catalysts
calcined
at 500 and 600°C, respectively;
specific
catalyst
was 77 m2/g, while
37 m'/g, a large increase
1400
1200
1000
with ammonia
and higher
that of Fe203 without
treated surface
by chemical
analysis
with 0.25 M H2S04 and area of the former
the sulfate
of the area being observed
1
SO3 content
treatment
was
1161.
800
Wave number, cm-l Fig. 2. IR spectra of Fe2(S04)3 (A) and Fe203-I catalysts treated with 3 M H2S04 (B), 1.5 M H2S04 CC), 0.5 M H2S04 (Dl, and 0.5 M (NH~)~S~~ (El. Calcination temperature: 5OO'C.
The
catalytic
superacids
action
at O°C [51. Si02-A1203
isomerization
Si02-A1203
of butane
which
is catalyzed
and it was found that the present
was examined,
for the skeletal
present
for the reaction
of butane
was totally
to isobutane
inactive
are concluded
Consequently,
by hydrolyzing
Fee13 with ammonia
had a tendency
to be converted
obtained
followed
forms, while
H2S04 gave only the oxide
Preparation
of S04/Ti02,
method
enhancement
of metal oxides
were obtained
ammonia,
prepared
isopropoxide
washing
The catalyst
Both catalysts
propane
material
under pulse reaction
[171.
was obtained
by
at 1OO'C.
ammonia
with
H4Ti04-II
followed
ion by pouring
was
by washing
0.5 M H2S04
(2 gf on a filter paper,
dried, and
and -11, respectively). isomerizations
Butane was converted
conditions,
and the catalytic
the maximum
The quantity
activity
of S was estimated
catalyst
calcined
of butane
and
into isobutane activity
and
of Ti02-I was
was observed by chemical
with analysis
at 525 and 650°C,
[161.
The superacid Zr(OH)4
of Zr02 was prepared
was obtained
from those are referred activities
f18-231.
H4Ti04-I
and drying
for the skeletal 1181.
of up to or oxides of
nitric acid, hydrolyzing
Tic14 with aqueous
to be 2.11 and 0.01% for the Ti02-I
201.
SOO'C
as follows.
five times as high as that of Ti02-II;
respectively
above
in aqueous
to as Ti02-I
were active
at 525'C
for MgO, CaO,
ion onto hydroxides
was treated with sulfate
at room temperature
calcination
was not observed
this The activity
with an acid strength
sulfate
the precipitate, aqueous
in air (referred
isobutane
addition
by calcination
(30 ml) on to the dried titanium calcined
and 0.5 M
one 1161.
to other metal oxides.
Solid superacids
by adsorbing
of TiO2 was prepared
by hydrolyzing
and drying.
was applied
by sulfate
Ti, Zr, Sn, and Si followed
aqueous
from Fe(N03)3
to
of
La203, Mn02, ThO2, Bi205, and Cr03, but for Ti02,
ZrO2, SnO2, and Si02 CL71.
titanium(W)
similar
to be a mixture
A1203 of the sulfate-supported iron oxide,
of catalyst
CuO, NiO, ZnO, CdO, A1203,
The superacid
the sulfate
The
ZrO2, Hf02. SnO2, Si02,
preparation
dissolving
the sample prepared
form without
on the basis of the results
Ho&-16.04
by treating
by using 0.25 and 0.5 M H2S04 showed the IR spectra
and Fe2(S04)3
of
the
into iron sulfate.
(C) in Fig. 2 [161; the latter sample gave the XRD pattern e-Fe203
or even
to be solid superacids.
prepared
catalysts
are
Acid strength
for the reaction.
with H2S04 and calcining
The material
catalysts
at room temperature
used was in the range of -12.70
catalysts
by
in the same manner
to as Zi02-I and Zr02-II,
for the reaction
as that of TiO2
from ZrOCl2 and .ZKO(NO~)~, and the catalysts respectively.
of butane were examined
119, prepared
The catalytic
[20], and the maximum
218 Table I. Time
Reaction
of butane
(h)
Product
24b 48b 24' 48'
distribution i-C4
C4
C3
over Zr02-I at 25°C.
78.9 59.7 68.4 34.2
0.1 1.3 1.1 4.8
(%ja C5
i-C5
0 Trace 0 Trace
Trace 1.3 Trace 3.2
20.4 31.7 30.5 57.8
aC3, C4, i-C4, C5, and i-C5 indicate propane, butane, isobutane, pentane, and isopentane, respectively. b The catalyst was heated again in air at 500°C for 1.5 h before reaction. 'The catalyst was evacuated at 25O'C for 3 h at 10-2-10-3 mmHg before the reaction. activity
was observed
Zr02-II. Zr02-I
The quantity
catalyst
respectively
calcined
isopentane butane
The catalyst
to be 2.8, 2.2, and 0.2 wt% for the
converted
and propane
propane
reactor
at 25'C over
are shown in Table
Pentane
and
as products
in addition
prepared
by heating
the Zr02-I
each
greatly
by calcination
as was observed
in
in the same group as Ti and Zr in transition
method
by exposing
of butane
The maximum
1241.
at 700°C, and this activity
activity
was close to that of
at 65O'C. of HO(-16.04
was synthesized
from the above stated cases; tin hydroxide
with pH=lO followed
The catalyst
at 55O'C.
which was obtained
of HfC14, to 1 M H2S04 and then calcining,
with an acid strength
from the solution
calcining
decreased
oxide is not effective
isomerization
calcined
preparation
temperature
at 100 and 400°C, then treating
at 41O"C, and thus, the treatment
The catalyst,
Table.
with calcination
catalyst
The Sn02 catalyst
obtained
of
at 500°C gave almost the same conversions
crystallizes
by the hydrolysis
for the skeletal
was observed
mixture
1171.
of the Periodic
different
Zr(OHj4
ion on the crystallized
prepared
Zr(OHj4
calcining
is the third element
was active
The amount of
to C3 and i-C4.
[201.
while the activities
of butane,
over 45O'C.
the case of Fe203
Hf(OHj4,
I.
after 48 h, 34.2%, is close to that of the equilibrium
for the reaction
metals
[201
out in a recirculation
The catalysts
Hafnium
and ethane
at 65O'C; the results
with 0.5 M H2S04 and finally
with sulfate
into methane
[191.
C4 and i-C4 at 25OC, 27 and 13%, respectively
of Zr(OHj4
at 500, 650, and 800°C,
of butane was carried
were observed
produced
for Zr02-I and 575'C for
with 0.5 M H2S04 and calcined
into butane
The reaction
at 625-650°C
of S was estimated
treated
[171.
and isobutane
Zr02-I
with calcination
was active
by exposing
by the was
to 3 M H2S04 and
for the reaction
of butane at room
[21, 221.
The Si02 catalyst,
which was obtained
followed
by drying
activity
for the dehydration
in a vacuum
by exposing
and calcining
of ethanol,
silica gel to S02C12
in air at 400°C, showed high
much higher
than that of Si02-A1203,
the
219
temperature
difference
between
both catalysts
over 4O'C; the silica gel was prepared few drops of HNO3, stirring maximum
activity
by dissolving
until gel formation,
was observed
Si(OC2H5)4
and drying
being
in water with a
at lOO*C
of HN03 were not effective
The
1231.
at 400°C, The treatment
with calcination
using NH3 instead
H2SOh and the gelation
to get the same conversions
with
to generate
superacidity. In the case of the sulfate-treated superacid
sites were not created
crystallized
oxides
oxide,
but on the amorphous
The superacrd
crystallization. y-A1203;
superacids
highly
active
of Fe, Ti, Zr, Hf, Si and Sn,
by the treatment
of sulfate
forms followed
of A1203 was prepared
catalysts
oxide rather than the amorphous
was obtained
by exposing
y-Al203
by calcination
to
from the crystallized
were obtained
crystallized
ion on the
by the treatment
on the
The most active
one 1251.
to 2.5 M H2S04 followed
by calcining
catalyst
in air at
550-650°C. Miscellaneous
catalysts
The catalytic were remarkably observed
activities dependent
with calcination
latter material the reaction
temperature;
at 625'C for Ti(SO4)2
of pentane
for the reaction of cumene the maximum
and 725OC for Zr(S04)2
of -13.16<
Hol-12.70
XRD analysis
as a superacid.
at 725°C to be a mixture
activity
1261.
and activity
showed Ti(SO,)2
of their crystallized
was The
for
calcined
at
oxide and
forms.
The preparation Zr(OH)4
method
was exposed
of catalyst
by calcination
into acetone
was
and Te04/Zr02
of hexane
dehydrocyclization calcination
in air.
observed
to selenate of selenic
The materials
and tellurate
caused propan-2-01
by the oxidative
on calcination
dehycirogenation
at 650°C; the catalysts
[ZSI.
of hexane
at 600-700°C,
catalysts
were reduced
The catalysts to benzene;
the selectivity
were quite effective
high activities
for the
were observed
being up to 84%.
contain
3.1, 1.7, and 0.4 wt% Se, that of Te of the 2'02 catalysts acid being
at 500, 650, and 8OO'C were shown to
4.0 and 3.8 wt% after calcination
treated with
at 500 and 800°C,
XPS experiments
to be Se combined Zr-Se-Zr
on
The 21-02 catalysts
with selenic
respectively.
acid and calcined
with H2 and then used for
treated
telluric
ions;
(H2Se04) or telluric
CO into CO2.
The Se04/Zr02 the reaction
solution
with 100% selectivity
The maximum activity
also converted
was applied
to a 0.05 M aqueous
(H6Te06) acid followed to convert t271.
and ZrfS04)2
showed an acid strength
625OC and ZrfS04f2 sulfate
of Ti(S04)2
on calcination
with the Se catalyst showed the surface structure with Zr elements as Se 2- In the bridging bidentate state,
[28, 291.
A dehydrogenation to 0.05 M (NH4j2Cr04
catalyst
for alkanes
was also obtained
followed
by calcination
by exposing
in air at 600-8OO'C
Zr(OHf4
and reduction
at
55O'C
(quantity of Cr: 0.5 wt% after reduction);
into benzene catalyst
with a selectivity
treated
with 0.05 M (NH4)2Cr04
of Zr02 without
the chromate
area is similar
to that of the sulfate
active
this catalyst
of up to 84% [303.
treatment
Specific
and calcined
superacid.
hexane
area of the
at 7OO'C was 57 m2/g; that
was only 15 m2/g.
This large increase
XPS of the catalyst
to be Cr 4+ , created
site for dehydrogenation
converted
surface
by reduction
in
showed the
of Cr04/Zr02
[301. The Fe203 catalysts conversion
of ethanol
treated
to 0.05 M H6Te06
Fe(OHj3
with tellurate
into acetone
2.0 wt%); this catalyst
followed
[311.
by calcination
showed a selectivity
The loading of Pt on the S04/Zr02 skeletal
isomerization
isopentane
The catalyst
331. octane
of alkanes;
from pentane
also produced
present
superacids
catalyst
confirm
whether
substances
in the
gave a steady yield of mixture
of isomers
with a higher
The catalyst
is usually
until use to avoid humidity. treatment
The former catalyst
of a glass ampule
showed high performance
[32,
value of
OXIDES
[35, 361.
with the sulfate
treatment.
catalyst
notes to be of help on the occasion
and sealed in an ampoule
(amount of Te:
[341.
OF SULFATE-METAL
There are several
in air at 6OO'C
by exposing
of up to 75% for 94% conversion.
the loaded catalyst
gasoline
for the selective
was obtained
up to 100 h, with the equilibrium
from light naphthas
PROPERTIES
ion are effective
The catalyst
obscuring
vision,
superacidity
differs
greatly
is a finely powdered whereas
of preparation
calcined
in a Pyrex tube
The appearance
from that without
of the the
solid which coats the wall
the latter is not.
has been generated
of the
This is a way to
Pictures
or not.
of the Ti02 and
Zr02 samples are shown in Fig. 3 [161. The catalyst vacuum
evacuated
The superacids
below
acid is usually
100°C.
higher
in activity
materials
obtained
from isopropoxide
are high in activity
when heated
the Fe203 superacid
The catalyst
of Fe203 and Sn02 show oxidizing
The catalysts
starting
to be deactivated
above 25O'C; in particular
at temperatures
with sulfuric
C.
turns to the colored matter
at temperatures
obtained
by the treatment
than that with ammonium action
in a
should be
at temperatures
of Ti and nitrates
sulfate.
above 100'
of Fe and Zr as
and easy to prepare.
Acidity Due to the heterogeneity are difficult estimate
to carry out and to interpret.
the acidity
well-known SiO2-Al203.
of solid superacids,
of a solid catalyst
acid-catalyzed
reactions;
accurate
acidity
measurements
The most simple and useful way to
is to test its catalytic
we usually
compare
activity
the activity
in
with that of
221
(A)
(Cl
(B)
(D)
(El
Fig. 3. Pictures of S04/Ti02-I (A), Ti02-I (B), SO,/ZrO,-I CC), Zr02-I CD), an ZrO2-I (E) in glass amp&less(
Table
II.
Basic indicators
Indicatora
of base-form:
an adsorbed
of suitable strength;
strength,
-11.99 -12.44 -12.70 -13.16 -13.75 -14.52 -16.04
colorless,
The acid strength convert
of superacid
pKa
m-Nitrotoluene p-Nitrofluorobenzene p-Nitrochlorobenzene m-Nitrochlorobenzene 2,4-Dinitrotoluene 2,4-Dinitrofluorobenzene 1,3,5_Trinitrotoluene aColor
used for the measurement
color
of acid-form:
of a solid is defined neutral
indicators
as the ability
base into its conjugate
adsorbed
yellow.
on a surface
acid
of the [371.
can give a measure
the conjugate acid strength.
Ho function
of the surface
acid of the indicator. For indicators
the pKa, the greater
is equal to or lower than the pKa of
color changes
is the acid strength
of the solid.
indicators
usually
used up until now.
then the value
Lower values of Ho correspond
undergoing
Hammett
to
of its acid
if the color is that of the acid form of the indicator,
of the Hammett
Surface
Thus, the color
used for the measurement The indicators
of superacid
to greater
in this way, the lower Table
II shows the
strength,
which we have
with higher pKa values are 2.4,6-
222
trichlorobenzene
(pKa=-16.121,
trinitrotoluene)H+
f2,4-dinitrofluorobensene)H+
C-18.361, and ip-methoxybenzaldehyde)H+
(-17.351, f-19.50)
(2,4,6-
[381, but we
have not used those yet. Acid strength of the Hammett
of the superacids
indicators,
sample in powder superacids toluene,
indicator
in nonpolar
hexane,
carbon tetrachloride, suitable
super-acid catalysts; use 1191.
The results dinitrotoluene
guaranteed
trinitrobenzene
(-16.04)
The acid strength
However,
grade sulfuryl
chloride
benzene,
chloride
was found
of the present
was dried over silica gel
was also found to be suitable
of m-nitrochlorobenzene
are summarized
is added to the
solvents,
sulfuryl
determination
IX,
(pKa -13.16),
221.
2,4-
(-14.52). and 1,3,5-
in Table
to be Ho&-16.04
III [16, 17, 20, 21, 22, 251. for ZrO2-I
(575'C), and Sn02 (55O'C) and -16.04
in organic
2,4-dinitrofluorobenzene
is estimated
in solvent
[371, but the Ti02 and ZrO2
colored
etc.
cyclohexane
with the indicators (-13.751,
dissolved
for the acid strength
Afterward,
by the visual color change method
solvent
(white color) were immediately
to be a solvent
before
where
form placed
was examined
(650°C),
for Ti02-I,
Zr02-II
-11 (525°C) and
(650°C).
Acid strength change method
of the Hf02 catalysts
of Hammett
indicators
to yellow after calcination. at 700°c, and its catalytic of the ZrO2-I considered superacid
Table III.
because
The maximum activity
(65O“C) catalyst.
Thus, the catalyst
Zro 2-1 (500*Cale (650'Cf' i8OO'Cf" -1xi5750C)e (650°Cje Ti02-I (500PCje (525Y)e (600"Cje -II(525"z)e Sn02 (55O'C) f A1203 (65O'C)
with calcination
treated
at 700°C is f241.
The
from the catalytic
of the catalysts.
pKa value of the Hammett -13.75
color
of butane was close to that
close to Ho=-16 on the surface
of the acid strength
-13.16
was observed
(brown); it is considered
of Fe203 is also colored
Catalyst
by the visual
of the color change of the materials
activity
for the reaction
to hold the acid strength
Measurement
could not be measured
indicator
-14.52
+b -I+ + + + + + +
i+ f + + + +
kc +
+
+
+
f f +
+ + rt +
-16.04 d + +
+
aCalcination temperature. Acidic color of the indicator was observed bdistinctly, 'slightly, and dwas not fCyclohexane. Prepared Solvent: eSulfuryl chloride: observed on the surface. from Zr0C12, ZrO(N03)2, Ti(0-i-pr)4, Tic14 for Zr02-I, Zr02-II. TiO2-I. TiO2-II, respectively.
223 surface
Table IV.
areas of the catalysts. Surface
Calcination temp. ("C)
Catalyst
area
without
with SGq2zro2-I
Zr02-II Ti02-I Ti02-II SILO2
.,,*3;; aMetal
oxides without
activity
showed
the highest
Surface
187 124 41 136 84 144 100 90 166 135
100 50 28 64 44 63 55 71 28 21
650
151 161
253 250
the sulfate
treated
acid strength
area and crystal
Specific
surface
the catalysts
areas of the catalysts
Figure
treatment.
Amorphous
and the Zr02 heat-treated monoclinic
The XRD spectra
treated
superacidity
treated
material
calcined
The XRD pattern
calcined
The degree of
at 410"C,
of tetragonal. and
into the latter form by calcination after calcination
are shown in Fig. 5.
at 500°C is almost
of SOq/Zr02-I
was completely
over
over ?OO'C
[l?,
The degree
of
the same as that of ZrO2
heated at 650°C, whose
a tetragonal
at EOO'C was almost
the
with the Zr02 and
oxide crystallizes
of a mixture
of the Zr02-I catalysts
was highest,
a large increase
catalysts.
were also observed
zirconium
form being developed
of S04/Zr02
at 35O'C.
sulfated
phenomena
hydrated
forms; the former converts
crystallization
[221.
the
Sn02 was much lower than that of SnO2 without
at 5OO“C consists
500°C, only the monoclinic 391.
of the SnO2 catalysts
The analogous
1171.
in particular
active and acidic
with
that the areas of
with those of the oxides without
on the highly
of the sulfated
IV, together
It is noteworthy
for the A1203 catalyst;
4 shows XRD spectra
Ti02 catalysts
close to
activity.
are shown in Table
[17, 21, 22, 251.
area was observed
crystallization sulfate
except
acidity
so far, the ZrO2 catalyst
as well as the highest
are much larger compared
treatment
in surface
at 5OO'C bears a surface we have synthesized
form
those of pure metal oxides
sulfate
treatment.
Among the superacids
Bl.
S042- a
500 650 800 575 650 525 600 525 550 600
that the catalyst
Ho=-13
(m2/g1
form; the pattern
coincident
of the
with that of Zr02
at 650°C.
Figure
6 shows the spectra
phase transformation by calcination.
of the TiO2-I
catalysts
[171.
of Ti02 is known to be from an anatase
It is seen that the temperature
The crystallographic form to a rutile one
of crystallization
or phase
224
I
I
I
I
20
30
40
50
I
I
60
70
2 e/de@
Fig. 4.
XRD profiles of Sn02 (A) and SO,/SnO, (B) calcined at 500'~
11 30
40
2 er'des
50
30
40
53
2wN
Fig. 5. XRD profiles of S04/Zr02-I and ZrOa-I. Calcination temperature: (A) 500°C, (B) 650°C, CC!)8OO'C.
225 transformation
of anatase
to r-utile form for S04/Ti02-I
that for pure Ti02; the pattern the TiOZ catalysts, The measurement
was pure anatase by scanning
the pictures
performed;
with the sulfate
well as the retardation
sulfate
microscope
than
of crystallization,
was
It is seen that the samples
into fine particles
the sulfate
Catalysts
of the Zr02
treatment.
in comparison
with
This must be a reason,
why specific
as
surface areas of the
are much larger than those of the oxides which have not undergone
the
treatment.
Specific
surface
the oxides without were prepared obtained one.
were cracked
without
is ~a. 2OO'C higher
at 525'C. most active among
system.
electron
are shown in Fig. 7 [161.
treatment
those of the substaces
catalysts
of S04/Ti02 -I treated
areas of the Al203 catalysts the sulfate
by the treatment
It is considered
after the treatment preparation
treatment
from the crystallized
on the crystallized
and highly active
than those of
These catalysts
as shown in Table IV.
oxides,
catalysts
on the surface
about by the different
method
area before and
of catalyst
[251.
TiO,-I
were
oxide rather than the amorphous
that the large difference
was brought
were much smaller
sO,/TiO,-I
(B)
L
2 e/des
Fig. 6. XRD profiles of S04/Ti02-I and Ti02-I. (A) 300°C, (B) 500°C, (C) 525°C. (D) 6OO'C.
Calcination
temperature:
226
(B)
(A) Fig. I.
AEM pictures
CATALYTIC
REACTIONS
of Zr02-I
BY SULFATE-METAL
About ten years have passed but the applications summarizes
in the consecutive suppress
a low temperature converted neopentane
of isopentane
the reaction
butane,
(2,2-dimethylpropane)
In esterification, used catalyst
on sulfated
+ isopentane + isobutane
should be carried
using a highly
into propane,
as catalysts
in the vapor phase,
steps of pentane
the reaction
selectively,
repeating
was examined;
at 650°C.
since this study began to be taken up seriously,
reactions
of pentane
(B) calcined
OXIDES
of solid superacids
the acid-catalyzed
In the reaction
(Al and S04/Zr02-I
the reaction
no reactivation
+ isobutane. for obtaining
1401.
pentane,
into methane,
Table V
metal oxides.
the reaction
is known to occur Thus, in order to better
out with a short contact
acidic catalyst isobutane,
are still few.
Cyclopentane
and isopentane,
ethane,
of ethanol
and propane
isopentane time and at was while
[171.
with acetic acid with the
of the ZrO2 catalyst
was needed
since
227 Reactions
Table V.
catalyzed
by solid superacids. References
Catalyst SO41"eOx
Reaction
Type of reaction
Zr02 Pentane 3 i-Pentane Isomerization zro2 Alkylation Methane + Ethylene 3 C3-C7 hydrocarbons 2rO2 i-Butane + Butenes +C5-Cl1 alkylates ZrO, o-Xylene + Styrene += Phenylxylylethane Toluene + PhCOCl + o-, m-, pAcylation Methylbenzophenone + HCl Toluene + (PhCO)20 + A1203, Zr02 Methylbenzophenones + PhCOOH zro2 Toluene + PhCOOH + Methylbenzophenones f H20 zro2 Toluene + CH3COOH + Methylacetophenones + H20 ZrO2 Chlorobenzene + o-Chlorobenzoyl chloride Esterification cl-~C4-0H + CH3COOH *Esters ZrO2 TiO2, Zr02 n-Octyl, 2-Ethylhexyl alcohol + Phthalic acid + Terephthalic, Ethanol + Acrylic acid -5 Ti.02, ZrO2 Methanol
+ Salicylic
acid +
Ethyl, Methyl vinyl ether _) Poly(ethy1, methyl vinyl ether) Butane, i-Butane + CO + CO2 Ethylene + A20 + Acetaldehyde + Acetone Cyclohexanol * Cyclohexanone
the catalytic However,
activity
remained
the TiO2 catalyst alcohol
the activity
because
of ZrO2 remaining
elimination
[47, 481.
between
Ti.02 and Zr02 catalysts at a high temperature
The Fe203 superacid hydrocarbons loo"c.
unchanged
for the repeated
The discrepancy
is 150°C, and it is considered
gave a 29% conversion
superacid
of oxidation [21, 221.
thus those superacids
operation
in the preparation
was found to be quite effective
by the sulfate
for the reaction
addition
the of
that the catalyst
of
at temperatures of butane
above
at 300°C to
where none of the reactions
treatment
1531.
was also observed
catalysts
without
as solid catalyst.
Iron and tin oxides are known to be oxidation would be the oxidation
acid
temperature
for oxidation
was performed
the sulfate
[501.
of phthalic
ion on the surface,
is more stable and effective
at 3OO'C over Fe203, without
enhancement
operation
of sulfate
form CO and CO2 in the ratio 4:6 under the conditions occurred
53 22 22
by the esterification
to CO and CO2 when the reaction
The catalyst
Fe203
for the repeated
of the elimination
sulfate
prepared
unchanged
was deactivated
with n-octyl
50 47, 48 51 47, 48 51 47, 48 51 52
TiO2, ZrO2
Polymerization Oxidation
40 41 42 43 25, 44 45, 46 25, 47 48, 49 47, 48 49 47, 48 49 45, 46
The activity with the Sn02 catalysts;
with superacidity.
STRUCTURE
OF ACID CENTERS
Experiments property; spectra
OF SULFATE-METAL
using XPS were carried
the spectra
OXIDES
out in order to elucidate
of the ZrO2 catalyst
are shown in Fig. 8 [54, 551.
of Zr 3d3/2, Zr 345/2, and 0 1s for S04/Zr02
consistent
with those for Zr02, 184.1,
(B. E.), respectively. which was similar
The former
treated
182.0, and 530.3 eV for binding
to that of Zr(S04)2.
is composed
peak
energy
at 532 eV,
The single peak of S 2p3/2 was observed Thus, it is concluded
of Zr02 and S04, not of Zr(S04j2.
On the other hand, the XPS spectra
of the Ti02 catalyst
be composed
of Ti02 and Ti(S04J2
XPS spectra
also showed the possibility
surface
The
at 65O'C were
sample also showed a shoulder
at 169.3 eV, whose value agreed with that of Zr(S04)2. that the surface
the surface
[561.
showed the surface to
In the case of the A1203 of bearing
superacid,
A1203 and A12(S04j3
the
on the
as is shown in Fig. 9 [251.
The IR spectra The samples
of the superacids
showed the spectra
of Zr02, Ti02, and Sn02 are shown in Fig. 10.
different
from those of metal
sulfates
(shown in
Fig. 2); all the materials showed absorption bands at 980-990, 1040, 1130-1150, and 1210-1230 cm -1 , which are assigned to the bidentate sulfate coordinated to metal
elements
[571.
The IR spectra conversion analogous between
of pyridine
examined;
on S04/Zr02-I(650°C)
showed the easy
of Lewis sites to Brb'nsted sites by water molecules results
were also observed
the preheating
reaction
adsorbed
conditions
temperature
before
the results
when heated
with the Ti02 superacid
of S04/Zr02
reaction
that Bransted
sites, were decreased thus the reaction the activities
on heating
by regeneration
sites, created
by heating
of butane
decreased
at the high temperatures
catalyzed
activity
by heating
by adsorption
The relation
under the pulse
for the reaction
The maximum
are shown in Fig. 11.
at 350°C, and the activities
It is considered
in a reactor
and activity
of butane was was observed
at 400 to 6OO'C.
of water on Lewis
in the He flow, and
by Briinsted acid was restrained.
at 500 and 55O'C were raised to those around
of the Brb'nsted sites
(A' and B' in the Figure),
was treated
followed
by heating
again in the He flow at 3OO'C for 1 h and performing
reaction
at 13O'C.
It is indicative
are easily
the reaction
Brhsted
changeable
of butane
acid
In fact, 300-4OO'C
where the
catalyst
catalysts
by moistening
The
[54, 551. [161.
with water at 12O'C after the reaction,
that Lewis and BrGnsted
by adsorption
being also catalyzed
or desorption
of water molecules,
by Brijnsted sites
site Lewis
acid
the
sites on the present
site
[54, 551.
229
Zr 3d3/2, 512
0 Is
(A)
(B)
(C)
1111(111111( 534
530
526
186
182
178
Binding energy, eV Fig. (Cl:
8. XPS spectra of ZrOZ ZrOZ-I (650'12).
catalysts.
(A):
Zr(S04j2,
Al 2~
0 1s
A
(A)
_I 540
535 eV
530
525
80
75 eV
70
Blndina energy
Fig.
9.
XPS
spectra
of Al,(SO,),
(A) and
S0,/A1203
(B).
(B):
S04/Zr02-I
(65O"C),
230
1300
1500
1100
900
Nave number, CB-~ Fig. 10. IR spectra of SO4/ZrO -1 (650°C) (A), SO4/Zr02-I S04/TiO2-I (525°C) CC), and SO4 3SnO2 (55O*C) CD).
From the above results, with Zr elements
in the bridging
the case of titanium the complex
is much stronger
present,
iron oxide
is a chelating
studied
in the absence whereas
in the presence
thus accounting spectroscopic 1651.
of sulfated
sulfate:
thus,
by the inductive
If water molecules
by IR spectroscopy
alumina
and titania
are
117, 55, 601.
suggested
161-631.
1641.
Saur and
and postulated
are bonded
to a bridged
Brijnsted acidity zirconia
in
of acid sites on sulfur- promoted
of H20 this is converted
of sulfated
et al. proposed
to Brijnsted acid sites
three oxygens of the sulfate
for the increased studies
complex
remarkably
by arrows.
that the structure
the structure of water,
to be SO4 combined
with that of a simple metal stronger
fBl,
The double bond nature of
ion 158, 591.
as illustrated
hidentate
appears
state as Okazaki
the Lewis acid sites are converted
Tanabe et al. proposed
others
compared
of Zr4' becomes
of S=O in the complex
structure
bidentate
oxide with sulfate
the Lewis acid strength effect
the surface
(8OO'C)
that,
to Al or Ti,
bidentate
Recent
a monodentate
sulfate,
laser Raman structure
231
Heating temperature of catalyst, "C Fig. 11. Catalytic activities of S04/Zr02-I (65O'C) preheated at various temperatures in a He flow before reaction (butane at 130°C). (0 ): Heat-treated (0): Exposed to water by injection at 12O'C and treated at various temperature. at various temperatures. A', B': After the reaction of butane (A, B), water (lull was injected at 12O'C followed by heating the catalyst at 3OOOC for 1 h and performing the reaction under the same conditions.
SUPERACIDS
BY METAL OXIDES
Although elevated
the sulfate
temperatures
THEMSELVES
superacids
the system of metal oxides. containing
any sulfate
temperatures
ammonium drying,
metatungstate
observed
anhydride
both reactions.
estimated
not
which can be used at
Zr(OHj4 was impregnated followed
method
with aqueous
by evaporating
The concentration
13 wt.% W after calcination
were quite effective
with tungstic
water,
was 15 wt.% W
at 650-950°C.
for the benzoylation
and for the reaction
of pentane;
at the surprisingly
The SiO2-A1203
The catalyst
at 50°C and for pentane on ZrO2
as follows.
[(NH,)6iH2W12040)-"H201
with calcination
conditions.
type of superacid,
at
with
The analogous
acid
(H2W04) which
in water.
The catalysts benzoic
superacids
[66-691.
was also formed by the kneading
is insoluble
another
of metal oxides,
in air at 600-1OOO'C.
based on the hydroxide, superacid
We have prepared
was prepared
and calcining
of heat-treatment
it is hoped to synthesize
ion but consisting
of over 800°C
The catalyst
are stable enough because
for preparation,
catalyst
treated
of toluene
the maximum
high temperatures
was totally
inactive
at 800°C was active
to be Has-14.52
166, 671.
The acid strength
by a color change method
was
of 800-85O'C
for
under the same
for isomerization
at 30"~‘ and XPS showed this catalyst
IW03/~r02(800~C11
with
activity
of butane
to be WO3 supported
of this catalyst
using Hammett
was
indicators.
232
I
I
I
I
I
40
20
60
26 /dea
(B): W03/Zr02 (A): W03 (700'C). Fig. 12. XRD profiles of W03/Zr02 catalysts. (800°C). (Cl: wo3/zro2 (1000"c). (D): W03/Zr02 prepared by calcining Zr(OHj4 at 700°C, impregnating with the tungstate and calcining at 7OO'C.
The catalysts
prepared
with the tungstate activities,
and finally
the spectra
precalcining
Zr(OHj4
to 800-85O'C
to be a monoclinic
W03 (D), while the materials
with that of the latter material
by impregnation calcination combines
calcined
then converts
system
from the inactive
similarly
prepared
coincident
CC), whose catalytic
activity
sites are not created form whose
form; i.e. tungsten
superacid
oxide
sites at the time when a
In fact, the appearance
material
of W03 from 600
of the former was almost
it to the crystalline
at
to the
from Zr(OHj4 dried
the crystallization
that superacid
was
by
and calcining
oxide, but on the amorphous
oxide to create
is formed.
prepared
in addition
at 1OOO'C
it is concluded
on the crystallized
with zirconium
tetragonal greatly
Therefore,
at
of Zr02, as was
by impregnating
prepared
forms without
of Zr(OH)4
of the catalysts
The catalyst
system
(B); the pattern
of calcination
low.
temperature
each
the same
by calcination
XRD measurement
at 7OO'C to Zr02 followed
at 1OO'C gave 100% tetragonal
was quite
greatly
are shown in Fig. 12.
700°C showed the pattern crystallized
superacids.
then impregnating
at 8OO'C gave almost
decreased
of over 4OO"C, the crystallization
with the sulfated
performed;
at 100-300°C,
Zr(OH)4
calcining
while the activities
temperatures observed
by heating
of the catalyst
from the crystallized
differs
oxide as shown
233
CD)
(B)
(A)
Fig. 13. Pictures of WO,/ZrO, catalysts. (B): WO, prepared (A): ZrO, (800°C). at 8OO'C. by calcining ammonium me
in Fig. 13.
(C) is white in color, W03 being highly dispersed
The former
the Zr02 lattice, WO3 itself
whereas
the latter
[16, 661.
This catalyst
preparation
impregnated
with molybdic
evaporating
water,
method
acid
drying,
benzoylation
of toluene
Si02-A1203;
by the visual
considered
Superacid crystallized catalyst.
sites were not created
by
was 5 wt.% MO
for the
at 750-800°C.
the acid strength
of the Hammett
Since the
was not
indicators.
higher
It is
than Ho=-12.70
with those of Moo3 and Zr02
material
different
(c_a. at
[16, 681.
of the molybdate
as was oberved
of the inactive
was
followed
which did not occur over
by impregnation
oxide was also completely
Zr(OH)4
XPS spectra of the sample treated
were consistent
The XRD pattern
The concentration
bears a surface acidity results.
oxide; ammonia
was effective
on calcination
green),
oxide, but on the hydroxide
crystallized hydroxide
anhydride,
(yellowish
in aqueous
in air.
color change method
from the reaction
[Mo03/Zr02(8000C)1
to molybdenum
The catalyst
were observed
that the catalyst
-13) judging 800°C
[681.
with benzoic
high activities
was itself colored
estimated
was applied
(H2M004) dissolved
and calcining
metal based on the hydroxide
catalyst
into
(D) is not, the color being close to that of
on the
in the case of the W03
prepared
from the
from that prepared
from the
as shown in Fig. 14 [681.
Molybdenum the present
oxide
is well known to be one of the oxidation
substance
would be an oxidation
catalyst
catalysts,
with superacidity
and thus whose new
234
I
I
20
I
I 40
I
I
60
2e/deg Fig. 14. XRD profiles of Mo03/Zr02 catalysts. (A): MoO3/ZrO2 prepared by impregnation of the molybdate on the crystallized 2x-02 (calcined at 7OO'C) followed by calcination at EOO'C. (B): Mo03/Zr02 (8OO'C).
Table VI.
Surface
areas of W03/Zr02
Surface W03/Zr02
Calcination temp ("C)
100 800 850 900 1000
is expected.
1.2% CO, 98% selectivity at 500-7OO'C surface
It is noteworthy
with the sulfate
The catalyst
was inactive
converted
2
methanol
catalyst
tungsten
by calcining
especially
shown to contain
acidity,
is strongly
and an excess of the sulfate
prepared
at 800°C.
by calcination
This value is estimated interacted
is decomposed
while calcining
with
oxides as was just observed
in the case of calcination
2.2 wt.% of S.
the amount of sulfur which as sulfate
are shown in Table VI.
are much larger compared
and molybdenum
with the highest
fact, fuming gas is observed
into 68% HCHO and
oxide prepared
areas of the W03 and Moo3 catalysts
superacids,
650°C, was already
34 15 6
[691.
that the areas of both catalysts
The S04/Zr02-I
Zr02
68 60 58 43 7
for HCHO, while molybdenum
those of the oxides without
monolayer,
area (m2/g) Mo03/Zr02
30 12
catalytic-action
Specific
catalysts.
44 39 35
600
H2Mo04
and MoO3/ZrO2
to be
with Zr02 in a
to form sulfur oxides.
the catalyst.
at
2.2 wt.% of S is
In
235
to 13 wt.% of W and 6.6 wt.% of MO, these values being
equivalent
the supported excess
quantities
of molybdenum
of the present
Sublimation
catalysts.
oxide was also observed
with calcination
just equal to
based on an
of the Moo3
catalyst. CONCLUSION
AND PROSPECTS
I have attempted
to present
and their catalytic
action,
Solid acid systems
stronger
the recent works on syntheses
together
as solid superacids.
Sulfate-supported
observed
metal oxides were stable because
Another
being
satisfactory
extensively
liquids
catalyst.
will undoubtedly
superacids
tungsten
by a new preparation
to other metal oxides
There are many reactions as an effective
of heat-treatment
in which
with the oxide
its stability
method
will be
for new solid superacids.
solid superacid
The convenience provide
at high
or molybdenum
method,
It is hoped that the preparation
so far.
applied
and are
of the sulfate was sometimes
type of superacid,
was prepared
on zirconia,
structure.
which were used
recently
thus it was hoped to synthesize
reaction,
system of metal oxides. supported
but elimination
for preparation,
during
and zeolites,
in the past, have been developed
as catalysts
categorized
temperatures
with some view of the surface
than silica-alumina
extensively
of solid superacids
might be expected
to perform
of using solids in place of corrosive
an incentive
to further
studies
in the use of
solid superacids.
REFERENCES 1
R. J. Gillespie,
2
R. J. Gillespie
&
Chem. Res, 1 (1968) 202. --
and T. E. Peel, Adv. Phys. Org. Chem., 2 (1972) 1.
3
G. A. Olah, G. K. S. Prakash,
and J. Sommer, I_ Science
4
G. A. Olah, G. K. S. Prakash,
and J. Sommer,
206 (1979) 13.
Superacids,
Wiley,
New York, 1985. 5
M. Hino and K. Arata,
6
T. Takeshita,
Chem. L&t.,
K. Arata,
(1979) 1259.
T. Sano, and K. Tanabe,
Kogyo Kaqaku
Zasshi,
69 (1966) 916. 7
K. Arata,
T. Takeshita, N. Azumi,
and K. Tanabe,
8
K. Arata,
9
K. Arata and I. Toyoshima,
Chem. -*n Lett _
10
K. Arata and I. Toyoshoma,
Shokubai,
11
K. Arata, K. Sato, and I. Toyoshima,
12. K. Arata,
and H. Sawamura,
u
Shokubai,
Chem. Sot. s., --
13
K. Yabe, K. Arata,
M. Hino and K. Arata,
and I. Toyoshima, Shokubai,
15
M. Hino and K. Arata,
Chem. Lett.
48
(1975) 2944.
(1974) 929. 17 (1975) 98P. J- /* Catal
K. Yabe, M. Hino, and I. Toyoshima,
14
8 (1966) 226.
42
(1976) 221.
Shokubai,
19 (1977) 246.
J. Catal., 57 (1979) 231.
-21 (1979) 217. (1979) 477.
236
16
M. Hino and K. Arata,
17
M. Hino, Ph.D. Thesis,
18
M. Hino and K. Arata, J- Chem. &
Chem. Commun.,
19
M. Hino, S. Kobayashi,
J. Am. --Chem. Sot., 101 (1979) 6439.
20
M. Hino and K. Arata, J- Chem. Sot., Chem. Commun.,
21
H. Matsuhashi,
M. Hino, and K. Arata,
22
H. Matsuhashi,
M. Hino, and K. Arata, Appl.
23
H. Matsuhashi,
M. Hino, and K. Arata, Hokkaido
Society
of Japan,
unpublished Hokkaido
data.
University,
and K. Arata,
Abstr.
Hokkaido,
Chem. e.,
Japan,
1982.
(1979) 1148.
(1980) 851. (1988) 1027.
Catal.,
z
(1990) 205.
Summer Meetinq
No. E15, 1989. _25 (1984) 143.
24
K. Arata and M. Hino, A-React
25
K. Arata and M. Hino, Appl. Catal.,
59 (1990) 197.
26
K. Arata, M. Hino, and N. Yamagata,
Bull. Chem. Sot. Jpn.. 63
27
M. Hino and K. Arata, -J. Chem. Sot., Chem. Commun.,
28
M. Hino and K. Arata, -Chem. Lett.,
Kinet. Catal. E.,
K. Arata and M. Hino, Shokubai,
30
M. Hino and K. Arata, _Ad--.# J. Chem
31
M. Hino and K. Arata, -J. Chem. Sot., Chem. Commun.,
32
s. Baba, Y. Shibata,
33
Abstr. 34
35
T.
and K. Kohsaka,
Japan Pat.
T. Imai, and N. Yokoyama, Nagoya,
16th National
October
1986,
p. 68.
Imai,
Nojima,
S.
T. Shimizu,
Society of Japan,
K. Arata,
in Shokubai
and S. Baba, 9
Sendai,
Kohza,
September
ed.by Catal.
National
Meetinq
Of the
1988, Abstr. NO. 3B307.
Sot. Japan, Kodansha
Scientific,
(19861, Vol. 11, p. 31.
36
K. Arata and M. Hino, Shokubai,
37
K. Tanabe,
in J. R. Anderson
K. Tanabe
-24 (1982) 241
and M. Boudart
Vol. 2, Springer-Verlag
Technoloqy, 38
(1988) 1168.
(1986).
Society of Japan,
Catalysis
Tokyo
(1987) 1355.
Chem. Commun
T. Kimura,
68138
H. Takaoka,
of the Petroleum --
(1984) 1037.
28 (1986) 413. Sot
H. Takaoka,
s. Baba, T. Shimizu, Meetinq
(1990) 244.
(1985) 1483.
29
(Toku Kai Shou) 61-68137,
of the Chemical ---
and R. Noyori,
Berlin,
(eds.), Catalysis-Science
Superacid-Superbase,
and
New York, 1981.
Heidelberg, Kodansha
Scientific,
Tokyo.
1980, p. 5. 39
J. Livage,
40
M. Hino and
K. Doi, and C. Mazieres,
41
M. S. Scurrell,
42
K.
K.
Hatakeyama,
Petroleum
Arata, d React
Kinet A-
Appl. Catal., 2 T. Suzuka,
R. A. Rajadhyaksha
44
K. Arata and M. Hino, National
45
T. Yamaguchi Irkutsk,
_19 (1982) 101.
and H. Ozaki, 28th National
43
October
SOC., 2
Catal. a.,
(1968) 349.
(1987) 109.
Society of Japan, Akita,
Hamamatsu,
J. Am. Ceram.
Meetinq
of the
July 1986, Abstr. NO. 38.
and D. D. Chaudhari, Meetinq
Ind. Eng. Chem. Res.. 26 (1987) 1743. of the Catalysis
Society of Japan,
1984, Abstr. NO. C37.
and K. Tanabe,
p. 20, 1983.
Proceed.
_7th Soviet-Japanese
Seminar _--*t
on Catal
237
T. Yamaguchi,
K. Akiyama,
46
K. Tanabe,
47
K. Arata and M. Hino, Shokubai,
48
K. Arata and M. Hino, Proceed.
Proceed.
Irkutsk,
8th Int. Gong.
Catal.,
A. Mitoh,
K. Iwabuchi,
and K. Isogai,
1984, p. v-601.
Berlin(West), 25 (1983) 124.
-7th Soviet-Japanese
Seminar
on Catal.,
p_ 7, 1983.
49
J. Chem. Sot M. Hino and K. Arata, _--J-d'
50
M. Hino and K. Arata,
51
M. Hino and K. Arata, Appl.
Chem. Commun
Chem. E.,
(1985) 112.
(1981) 1671.
$j
Catal.,
(1985) 401.
(1980) 963.
Chem. s.,
52
M. Hino and K. Arata,
53
M. Hino, S. Kobayashi,
54
M. Hino, K. Arata,
55
K. Arata and M. Hino, Hyomen, 19
(1981) 75.
56
M. Hino and K. Arata,
(1990) 481.
57
K. Nakamoto,
58
A. Kurosaki
59
S. Okazaki,
60
K. Tanabe,
and K. Arata, _A----React. Kinet
18 (1981)
Catal. Lett
491. and K. Yabe, Shokubai,
Hyomen, 28,
J. Fujita,
S. Tanaka,
-22 (1980) 232.
and M. Kobayashi,
J- --Am. Chem. SOC., 79
(1957) 4904. and S. Okazaki, T. Chinone, Proceed.
Texas A & M Univ., 61
T. Jin, M. Machida,
Nippon Kagaku
and A. Kurosaki,
-2nd Symposium College
(1976) 1816.
Nippon Kaqaku
Ind.-Univ.
Station,
T. Yamaguchi,
kaishi,
Kaishi,
Cooperation
(1977) 1282.
Chem. PToq.,
TX, 1984, p. 71.
and K. Tanabe,
Inorg. Chem.,
23
(1984)
4396. 62
T.
Yamaguchi,
63
T.
Jin, T. Yamaguchi,
T. Jin, and K. Tanabe, and K. Tanabe,
J. Phys. -Chem.,
64
0.
Saur, M. Bensitel,
A. B. Mohammed
Saad, J. C. Lavalley,
B. A. Morrow,
J. Catal.,
99
65
K. Hatakeyama
and T. Hisamitsu,
66
K. Arata and M. Hino, Proceed.
J. Phys. Chem., 90 (1986) 3148. 90 (1986) 4794. C. P. Tripp,
and
(1986) 104. unpublished
data.
9th Int. Gong. --
Catal.,
Calgary,
Canada,
P- 1721. 67
M. Hino and K. Arata, -J. Chem. a
68
M. Hino and K. Arata,
69
K. Arata and M. Hino, Shokubai,
Chem. _*I Commun -
Chem. E.,
(1989) 971.
11
(1989) 477.
(1988) 1259.
1988,
213
REVIEW
PREPARATION
K.
OF SUPERACIDS
BY METAL OXIDES AND THEIR CATALYTIC
ACTION
iwATA*
Department
Hokkaido
of Science, Hakodate
Hachiman-cho,
University
of Education,
040 (Japan)
M. HINO Hakodate
Technical
College,
Tokura-cho,
Hakodate
042 (Japan)
ABSTRACT Our recent works on syntheses tungsten
or molybdenum
are reviewed. obtained
oxide
A1203
by adsorbing
is prepared
Superacids Ho(-14.52
sulfate
supporting
on zirconia,
ion onto hydroxides
from the crystallized
synthesized
themselves
are satisfactorily
which are generally discussed
catalyzed
and on their catalytic of up to Ho(-16.04
or amorphous
oxides of Fe, Ti,
with an acid strength
of
of up to
as that of the sulfate
Surface areas of the superacids
active
sulfate,
tungsten
in a heterogeneous
by strong acid.
on the basis of the results
action are
in air above 5OO'C; a superacid
in the same manner
Zr02 with W03 or Mo03.
oxides and
oxide.
with those of the oxides without
The superacids
sulfate-metal
with an acid strength
by calcination
by metal oxides
are
compared
supported
Solid superacids
Zr, Hf, Sn, and Si followed
of solid superacids,
Structure
superacid
by
are much larger
or molybdenum
oxide.
system for reactions
of acid sites is
of XPS, IR, and XRD spectra.
INTRODUCTION Following acidity
Gillespie's
is stronger
superacidity by mixing
has been reached
Lewis acid
such superacids
articles
arises
applications
Brijnsted acid
(BF3, SbF5,
TaF5,
etc.).
Ho&-12
superacid [l, 21.
when its Such a
which are generally
(HF. HS03F. CF3S03H. The interest
made up
etc.) and a
which has grown in
from the new areas which have been opened as well in as in the hydrocarbon
have been recently
025#584190/$3.50
any acid may be termed
by a number of systems
a flu'orine containing
fluorinated
synthetic
definition
than that of 100% H2S04, i.e.,
reviewed
by Olah
chemistry
field.
The research
[3, 43.
0 Etsevier Sequoia/Printed
in The ~etherIands
214 Solid acids have been extensively carriers
in chemical
industry
acids,
catalysts
oxides
of Si02-A1203,
Si02-Al203 organic
with high surface
bears
reactions.
The preparation
gasoline,
acids.
reactor
of homogeneous
in particular
and has been applied
of Si02-Al203
alkylation, advantages
and reutilization solid catalysts
are active areas
acylation,
methanol
of solid catalysts,
continuous
of the catalyst.
for disposal
and zeolites
as solid superacids.
operation,
Furthermore,
the
no corrosion
stronger
have been developed
The search
our recent works on syntheses
sulfate-supported
metal
as well
of the
of used catalyst.
solid acid systems
chemistry,
solid
solid acids as
to bring about an ease of
which allows
can lead to other advantages, problem
to
recent
of stronger
for solid superacids
of solid superacids
oxides and tungsten
than acidic
recently
and are
has become
since the early 197Os, and it is now the age of superacid.
action:
to various
has been determined
and characterization
is expected
mixture,
such as silica-alumina
summarizes
of solid
are the binary
liquid acids by heterogeneous
industry
and no environmental
categorized active
cracking,
of the reported
In the field of catalysis oxides
than Ho=-8.2
and Si02-Zr02;
acid strength
on the preparation
from the reaction
heterogeneous
stronger
and use of strong solid acids and superacids
in the chemical
as regeneration
or catalyst
Among a large number
[51, whose value is in the range of superacidity.
Because
Replacement
separation
acidity
Si02-Ti02,
The highest
has focused
catalysts
Ti02-Zr02,
for isomerization,
etc.
research
and used as catalysts
strong acid sites on the surface
so far to be Ho+-12
of research
studied
for many years.
This review
and their catalytic
or molybdenum
oxide supported
on zirconia.
SUPERACIDS
OF SULFATE-METAL
Benzylation Friedel-Crafts
of toluene alkylation,
and iron sulfates The activities activity
showed an unexpected
7OO'C have the following decompose proceeds
with calcination
at 700°C
calcined
properties:
rapidly,
temperature,
Preparation
of
[6-81. the maximum
[9-111.
at various
temperatures
that iron sulfates (1) The sulfates
and (2) the slight amount of sulfur of the sulfate
example
and sulfates,
for the reaction
to form CI-Fe203 at 675 to 7OO"C, and afterwards
the decomposition
salts exists mainly
were examined
heat-treated
at
completely
the crystallization
(0.15 wt%) remaining
after
as S042- on the surface.
of S04/Fe203
On the basis of the above results treated
is a typical
on calcination
It was concluded surface
which
over several metal oxides
effectiveness
dependent
of FeS04 and Fe2(S04)3
by XPS and XRD [12, 131.
chloride,
was performed
were remarkably
being observed
Surfaces
OXIDES with benzyl
at 700°C, sulfate-treated
for the surface
properties
ion oxides were differently
of iron sulfates
prepared,
and the
215 catalytic
effect
of sulfate
found that remarkable activity
of Fe203 result
treatment
in the surface
from the sulfate
(Fe203-I) Ltd.)
Works,
was prepared
ammonium
sulfate
and calcined
0.25-0.5
M H2S04 showed unexpectedly
2-propanol,
in air at 500-550°C.
Fe(OHj3.
treated
by heat-
After drying,
high activities
with ammonium
ion
2-propanol
activities
The maximum
for the sample
former activity
activity
sulfate acid.
of the sulfate
of the Fe203-I
are shown as a function
Fig. 1 1161.
were
the materials treated
for the reaction
with
of
catalyst
of calcination was observed
treated with sulfuric
was due to the catalytic
action
latter one was based on acid sites created
at 550-75O'C;
for the reaction
temperature
this
of
of the catalyst
in
at 300 and
It is considered
by the mounted
by strong
the
to form SO3.
with cafcination acid.
prepared
also enhanced
TGA data of the
showed a weight decrease
was caused by decomposition
The catalytic
(Kokusan
acid or aqueous
did not occur at all over the catalysts
The treatment
with sulfate
sulfuric
The Fe203 catalysts
to the same extent as that with sulfuric
catalysts
450-5OO'C
followed
Iron hydroxides
to aqueous
(30 ml) on a filter paper.
though the reaction
by calcining
decrease
and in the catalytic
ion treatment
as follows.
(2 g) were exposed
powdered
activity
It was
was examined.
acidity
[14, 151.
The catalyst Chemical
ion on solid acid catalysts
increases
that the
acid, but the
interaction
of the ion with
60
0 200
300
400
500
600
Co~cinotion temperature, "C Fig. 1. Reaction of 2-propanol to propylene over Fe203-I treated with 0.5 M H2S04 (@ 1 or (NH4)2S04 ( 0) and calcined at various temperatures. Pulse reaction conditions: He carrier 30 cm/min, pulse size 0.4 Ul (liquid), catalyst 30 mg, temperature 17O'C.
216 the support. maximum
In the case of the sample treated
activity
temperatures reasonable
below judging
The material adsorption
with ealcination
treated
with sulfate
sulfate
shown in Fig. 2 [15, 171. activity,
sulfate,
the at
seem to be
of ammonium
ion of 0.5 M concentration
sulfate
showed
itself.
IR
1120, and 1220 cm -1 , which are assigned
1030-1060,
coordinated
The results
ineffectiveness
to metal elements,
1.5 and 3 M showed the IR spectra
catalytic
with ammonium
at 500°C, and the calcination
300°C did not give activity. from the catalytic
bands at 980-990,
to the bidentate with
was observed
quite similar
The treatments
while the samples
treated
to those of iron sulfate
with S02, H2S and SO3 also promoted
the IR spectra of those
substances
being similar
as the
to (n) or
(E) in Fig. 2 115, 161. The Fe203-II subjected
than the Fe203-I
I prepared by hydrolyzing
catalyst
to the similar
treatment
showed higher
The quantity
catalyst.
Fe(N03)3 activity
of S was estimated
to be 0.92 and 0.23 wt% for the Fe203-II
catalysts
calcined
at 500 and 600°C, respectively;
specific
catalyst
was 77 m2/g, while
37 m'/g, a large increase
1400
1200
1000
with ammonia
and higher
that of Fe203 without
treated surface
by chemical
analysis
with 0.25 M H2S04 and area of the former
the sulfate
of the area being observed
1
SO3 content
treatment
was
1161.
800
Wave number, cm-l Fig. 2. IR spectra of Fe2(S04)3 (A) and Fe203-I catalysts treated with 3 M H2S04 (B), 1.5 M H2S04 CC), 0.5 M H2S04 (Dl, and 0.5 M (NH~)~S~~ (El. Calcination temperature: 5OO'C.
The
catalytic
superacids
action
at O°C [51. Si02-A1203
isomerization
Si02-A1203
of butane
which
is catalyzed
and it was found that the present
was examined,
for the skeletal
present
for the reaction
of butane
was totally
to isobutane
inactive
are concluded
Consequently,
by hydrolyzing
Fee13 with ammonia
had a tendency
to be converted
obtained
followed
forms, while
H2S04 gave only the oxide
Preparation
of S04/Ti02,
method
enhancement
of metal oxides
were obtained
ammonia,
prepared
isopropoxide
washing
The catalyst
Both catalysts
propane
material
under pulse reaction
[171.
was obtained
by
at 1OO'C.
ammonia
with
H4Ti04-II
followed
ion by pouring
was
by washing
0.5 M H2S04
(2 gf on a filter paper,
dried, and
and -11, respectively). isomerizations
Butane was converted
conditions,
and the catalytic
the maximum
The quantity
activity
of S was estimated
catalyst
calcined
of butane
and
into isobutane activity
and
of Ti02-I was
was observed by chemical
with analysis
at 525 and 650°C,
[161.
The superacid Zr(OH)4
of Zr02 was prepared
was obtained
from those are referred activities
f18-231.
H4Ti04-I
and drying
for the skeletal 1181.
of up to or oxides of
nitric acid, hydrolyzing
Tic14 with aqueous
to be 2.11 and 0.01% for the Ti02-I
201.
SOO'C
as follows.
five times as high as that of Ti02-II;
respectively
above
in aqueous
to as Ti02-I
were active
at 525'C
for MgO, CaO,
ion onto hydroxides
was treated with sulfate
at room temperature
calcination
was not observed
this The activity
with an acid strength
sulfate
the precipitate, aqueous
in air (referred
isobutane
addition
by calcination
(30 ml) on to the dried titanium calcined
and 0.5 M
one 1161.
to other metal oxides.
Solid superacids
by adsorbing
of TiO2 was prepared
by hydrolyzing
and drying.
was applied
by sulfate
Ti, Zr, Sn, and Si followed
aqueous
from Fe(N03)3
to
of
La203, Mn02, ThO2, Bi205, and Cr03, but for Ti02,
ZrO2, SnO2, and Si02 CL71.
titanium(W)
similar
to be a mixture
A1203 of the sulfate-supported iron oxide,
of catalyst
CuO, NiO, ZnO, CdO, A1203,
The superacid
the sulfate
The
ZrO2, Hf02. SnO2, Si02,
preparation
dissolving
the sample prepared
form without
on the basis of the results
Ho&-16.04
by treating
by using 0.25 and 0.5 M H2S04 showed the IR spectra
and Fe2(S04)3
of
the
into iron sulfate.
(C) in Fig. 2 [161; the latter sample gave the XRD pattern e-Fe203
or even
to be solid superacids.
prepared
catalysts
are
Acid strength
for the reaction.
with H2S04 and calcining
The material
catalysts
at room temperature
used was in the range of -12.70
catalysts
by
in the same manner
to as Zi02-I and Zr02-II,
for the reaction
as that of TiO2
from ZrOCl2 and .ZKO(NO~)~, and the catalysts respectively.
of butane were examined
119, prepared
The catalytic
[20], and the maximum
218 Table I. Time
Reaction
of butane
(h)
Product
24b 48b 24' 48'
distribution i-C4
C4
C3
over Zr02-I at 25°C.
78.9 59.7 68.4 34.2
0.1 1.3 1.1 4.8
(%ja C5
i-C5
0 Trace 0 Trace
Trace 1.3 Trace 3.2
20.4 31.7 30.5 57.8
aC3, C4, i-C4, C5, and i-C5 indicate propane, butane, isobutane, pentane, and isopentane, respectively. b The catalyst was heated again in air at 500°C for 1.5 h before reaction. 'The catalyst was evacuated at 25O'C for 3 h at 10-2-10-3 mmHg before the reaction. activity
was observed
Zr02-II. Zr02-I
The quantity
catalyst
respectively
calcined
isopentane butane
The catalyst
to be 2.8, 2.2, and 0.2 wt% for the
converted
and propane
propane
reactor
at 25'C over
are shown in Table
Pentane
and
as products
in addition
prepared
by heating
the Zr02-I
each
greatly
by calcination
as was observed
in
in the same group as Ti and Zr in transition
method
by exposing
of butane
The maximum
1241.
at 700°C, and this activity
activity
was close to that of
at 65O'C. of HO(-16.04
was synthesized
from the above stated cases; tin hydroxide
with pH=lO followed
The catalyst
at 55O'C.
which was obtained
of HfC14, to 1 M H2S04 and then calcining,
with an acid strength
from the solution
calcining
decreased
oxide is not effective
isomerization
calcined
preparation
temperature
at 100 and 400°C, then treating
at 41O"C, and thus, the treatment
The catalyst,
Table.
with calcination
catalyst
The Sn02 catalyst
obtained
of
at 500°C gave almost the same conversions
crystallizes
by the hydrolysis
for the skeletal
was observed
mixture
1171.
of the Periodic
different
Zr(OHj4
ion on the crystallized
prepared
Zr(OHj4
calcining
is the third element
was active
The amount of
to C3 and i-C4.
[201.
while the activities
of butane,
over 45O'C.
the case of Fe203
Hf(OHj4,
I.
after 48 h, 34.2%, is close to that of the equilibrium
for the reaction
metals
[201
out in a recirculation
The catalysts
Hafnium
and ethane
at 65O'C; the results
with 0.5 M H2S04 and finally
with sulfate
into methane
[191.
C4 and i-C4 at 25OC, 27 and 13%, respectively
of Zr(OHj4
at 500, 650, and 800°C,
of butane was carried
were observed
produced
for Zr02-I and 575'C for
with 0.5 M H2S04 and calcined
into butane
The reaction
at 625-650°C
of S was estimated
treated
[171.
and isobutane
Zr02-I
with calcination
was active
by exposing
by the was
to 3 M H2S04 and
for the reaction
of butane at room
[21, 221.
The Si02 catalyst,
which was obtained
followed
by drying
activity
for the dehydration
in a vacuum
by exposing
and calcining
of ethanol,
silica gel to S02C12
in air at 400°C, showed high
much higher
than that of Si02-A1203,
the
219
temperature
difference
between
both catalysts
over 4O'C; the silica gel was prepared few drops of HNO3, stirring maximum
activity
by dissolving
until gel formation,
was observed
Si(OC2H5)4
and drying
being
in water with a
at lOO*C
of HN03 were not effective
The
1231.
at 400°C, The treatment
with calcination
using NH3 instead
H2SOh and the gelation
to get the same conversions
with
to generate
superacidity. In the case of the sulfate-treated superacid
sites were not created
crystallized
oxides
oxide,
but on the amorphous
The superacrd
crystallization. y-A1203;
superacids
highly
active
of Fe, Ti, Zr, Hf, Si and Sn,
by the treatment
of sulfate
forms followed
of A1203 was prepared
catalysts
oxide rather than the amorphous
was obtained
by exposing
y-Al203
by calcination
to
from the crystallized
were obtained
crystallized
ion on the
by the treatment
on the
The most active
one 1251.
to 2.5 M H2S04 followed
by calcining
catalyst
in air at
550-650°C. Miscellaneous
catalysts
The catalytic were remarkably observed
activities dependent
with calcination
latter material the reaction
temperature;
at 625'C for Ti(SO4)2
of pentane
for the reaction of cumene the maximum
and 725OC for Zr(S04)2
of -13.16<
Hol-12.70
XRD analysis
as a superacid.
at 725°C to be a mixture
activity
1261.
and activity
showed Ti(SO,)2
of their crystallized
was The
for
calcined
at
oxide and
forms.
The preparation Zr(OH)4
method
was exposed
of catalyst
by calcination
into acetone
was
and Te04/Zr02
of hexane
dehydrocyclization calcination
in air.
observed
to selenate of selenic
The materials
and tellurate
caused propan-2-01
by the oxidative
on calcination
dehycirogenation
at 650°C; the catalysts
[ZSI.
of hexane
at 600-700°C,
catalysts
were reduced
The catalysts to benzene;
the selectivity
were quite effective
high activities
for the
were observed
being up to 84%.
contain
3.1, 1.7, and 0.4 wt% Se, that of Te of the 2'02 catalysts acid being
at 500, 650, and 8OO'C were shown to
4.0 and 3.8 wt% after calcination
treated with
at 500 and 800°C,
XPS experiments
to be Se combined Zr-Se-Zr
on
The 21-02 catalysts
with selenic
respectively.
acid and calcined
with H2 and then used for
treated
telluric
ions;
(H2Se04) or telluric
CO into CO2.
The Se04/Zr02 the reaction
solution
with 100% selectivity
The maximum activity
also converted
was applied
to a 0.05 M aqueous
(H6Te06) acid followed to convert t271.
and ZrfS04)2
showed an acid strength
625OC and ZrfS04f2 sulfate
of Ti(S04)2
on calcination
with the Se catalyst showed the surface structure with Zr elements as Se 2- In the bridging bidentate state,
[28, 291.
A dehydrogenation to 0.05 M (NH4j2Cr04
catalyst
for alkanes
was also obtained
followed
by calcination
by exposing
in air at 600-8OO'C
Zr(OHf4
and reduction
at
55O'C
(quantity of Cr: 0.5 wt% after reduction);
into benzene catalyst
with a selectivity
treated
with 0.05 M (NH4)2Cr04
of Zr02 without
the chromate
area is similar
to that of the sulfate
active
this catalyst
of up to 84% [303.
treatment
Specific
and calcined
superacid.
hexane
area of the
at 7OO'C was 57 m2/g; that
was only 15 m2/g.
This large increase
XPS of the catalyst
to be Cr 4+ , created
site for dehydrogenation
converted
surface
by reduction
in
showed the
of Cr04/Zr02
[301. The Fe203 catalysts conversion
of ethanol
treated
to 0.05 M H6Te06
Fe(OHj3
with tellurate
into acetone
2.0 wt%); this catalyst
followed
[311.
by calcination
showed a selectivity
The loading of Pt on the S04/Zr02 skeletal
isomerization
isopentane
The catalyst
331. octane
of alkanes;
from pentane
also produced
present
superacids
catalyst
confirm
whether
substances
in the
gave a steady yield of mixture
of isomers
with a higher
The catalyst
is usually
until use to avoid humidity. treatment
The former catalyst
of a glass ampule
showed high performance
[32,
value of
OXIDES
[35, 361.
with the sulfate
treatment.
catalyst
notes to be of help on the occasion
and sealed in an ampoule
(amount of Te:
[341.
OF SULFATE-METAL
There are several
in air at 6OO'C
by exposing
of up to 75% for 94% conversion.
the loaded catalyst
gasoline
for the selective
was obtained
up to 100 h, with the equilibrium
from light naphthas
PROPERTIES
ion are effective
The catalyst
obscuring
vision,
superacidity
differs
greatly
is a finely powdered whereas
of preparation
calcined
in a Pyrex tube
The appearance
from that without
of the the
solid which coats the wall
the latter is not.
has been generated
of the
This is a way to
Pictures
or not.
of the Ti02 and
Zr02 samples are shown in Fig. 3 [161. The catalyst vacuum
evacuated
The superacids
below
acid is usually
100°C.
higher
in activity
materials
obtained
from isopropoxide
are high in activity
when heated
the Fe203 superacid
The catalyst
of Fe203 and Sn02 show oxidizing
The catalysts
starting
to be deactivated
above 25O'C; in particular
at temperatures
with sulfuric
C.
turns to the colored matter
at temperatures
obtained
by the treatment
than that with ammonium action
in a
should be
at temperatures
of Ti and nitrates
sulfate.
above 100'
of Fe and Zr as
and easy to prepare.
Acidity Due to the heterogeneity are difficult estimate
to carry out and to interpret.
the acidity
well-known SiO2-Al203.
of solid superacids,
of a solid catalyst
acid-catalyzed
reactions;
accurate
acidity
measurements
The most simple and useful way to
is to test its catalytic
we usually
compare
activity
the activity
in
with that of
221
(A)
(Cl
(B)
(D)
(El
Fig. 3. Pictures of S04/Ti02-I (A), Ti02-I (B), SO,/ZrO,-I CC), Zr02-I CD), an ZrO2-I (E) in glass amp&less(
Table
II.
Basic indicators
Indicatora
of base-form:
an adsorbed
of suitable strength;
strength,
-11.99 -12.44 -12.70 -13.16 -13.75 -14.52 -16.04
colorless,
The acid strength convert
of superacid
pKa
m-Nitrotoluene p-Nitrofluorobenzene p-Nitrochlorobenzene m-Nitrochlorobenzene 2,4-Dinitrotoluene 2,4-Dinitrofluorobenzene 1,3,5_Trinitrotoluene aColor
used for the measurement
color
of acid-form:
of a solid is defined neutral
indicators
as the ability
base into its conjugate
adsorbed
yellow.
on a surface
acid
of the [371.
can give a measure
the conjugate acid strength.
Ho function
of the surface
acid of the indicator. For indicators
the pKa, the greater
is equal to or lower than the pKa of
color changes
is the acid strength
of the solid.
indicators
usually
used up until now.
then the value
Lower values of Ho correspond
undergoing
Hammett
to
of its acid
if the color is that of the acid form of the indicator,
of the Hammett
Surface
Thus, the color
used for the measurement The indicators
of superacid
to greater
in this way, the lower Table
II shows the
strength,
which we have
with higher pKa values are 2.4,6-
222
trichlorobenzene
(pKa=-16.121,
trinitrotoluene)H+
f2,4-dinitrofluorobensene)H+
C-18.361, and ip-methoxybenzaldehyde)H+
(-17.351, f-19.50)
(2,4,6-
[381, but we
have not used those yet. Acid strength of the Hammett
of the superacids
indicators,
sample in powder superacids toluene,
indicator
in nonpolar
hexane,
carbon tetrachloride, suitable
super-acid catalysts; use 1191.
The results dinitrotoluene
guaranteed
trinitrobenzene
(-16.04)
The acid strength
However,
grade sulfuryl
chloride
benzene,
chloride
was found
of the present
was dried over silica gel
was also found to be suitable
of m-nitrochlorobenzene
are summarized
is added to the
solvents,
sulfuryl
determination
IX,
(pKa -13.16),
221.
2,4-
(-14.52). and 1,3,5-
in Table
to be Ho&-16.04
III [16, 17, 20, 21, 22, 251. for ZrO2-I
(575'C), and Sn02 (55O'C) and -16.04
in organic
2,4-dinitrofluorobenzene
is estimated
in solvent
[371, but the Ti02 and ZrO2
colored
etc.
cyclohexane
with the indicators (-13.751,
dissolved
for the acid strength
Afterward,
by the visual color change method
solvent
(white color) were immediately
to be a solvent
before
where
form placed
was examined
(650°C),
for Ti02-I,
Zr02-II
-11 (525°C) and
(650°C).
Acid strength change method
of the Hf02 catalysts
of Hammett
indicators
to yellow after calcination. at 700°c, and its catalytic of the ZrO2-I considered superacid
Table III.
because
The maximum activity
(65O“C) catalyst.
Thus, the catalyst
Zro 2-1 (500*Cale (650'Cf' i8OO'Cf" -1xi5750C)e (650°Cje Ti02-I (500PCje (525Y)e (600"Cje -II(525"z)e Sn02 (55O'C) f A1203 (65O'C)
with calcination
treated
at 700°C is f241.
The
from the catalytic
of the catalysts.
pKa value of the Hammett -13.75
color
of butane was close to that
close to Ho=-16 on the surface
of the acid strength
-13.16
was observed
(brown); it is considered
of Fe203 is also colored
Catalyst
by the visual
of the color change of the materials
activity
for the reaction
to hold the acid strength
Measurement
could not be measured
indicator
-14.52
+b -I+ + + + + + +
i+ f + + + +
kc +
+
+
+
f f +
+ + rt +
-16.04 d + +
+
aCalcination temperature. Acidic color of the indicator was observed bdistinctly, 'slightly, and dwas not fCyclohexane. Prepared Solvent: eSulfuryl chloride: observed on the surface. from Zr0C12, ZrO(N03)2, Ti(0-i-pr)4, Tic14 for Zr02-I, Zr02-II. TiO2-I. TiO2-II, respectively.
223 surface
Table IV.
areas of the catalysts. Surface
Calcination temp. ("C)
Catalyst
area
without
with SGq2zro2-I
Zr02-II Ti02-I Ti02-II SILO2
.,,*3;; aMetal
oxides without
activity
showed
the highest
Surface
187 124 41 136 84 144 100 90 166 135
100 50 28 64 44 63 55 71 28 21
650
151 161
253 250
the sulfate
treated
acid strength
area and crystal
Specific
surface
the catalysts
areas of the catalysts
Figure
treatment.
Amorphous
and the Zr02 heat-treated monoclinic
The XRD spectra
treated
superacidity
treated
material
calcined
The XRD pattern
calcined
The degree of
at 410"C,
of tetragonal. and
into the latter form by calcination after calcination
are shown in Fig. 5.
at 500°C is almost
of SOq/Zr02-I
was completely
over
over ?OO'C
[l?,
The degree
of
the same as that of ZrO2
heated at 650°C, whose
a tetragonal
at EOO'C was almost
the
with the Zr02 and
oxide crystallizes
of a mixture
of the Zr02-I catalysts
was highest,
a large increase
catalysts.
were also observed
zirconium
form being developed
of S04/Zr02
at 35O'C.
sulfated
phenomena
hydrated
forms; the former converts
crystallization
[221.
the
Sn02 was much lower than that of SnO2 without
at 5OO“C consists
500°C, only the monoclinic 391.
of the SnO2 catalysts
The analogous
1171.
in particular
active and acidic
with
that the areas of
with those of the oxides without
on the highly
of the sulfated
IV, together
It is noteworthy
for the A1203 catalyst;
4 shows XRD spectra
Ti02 catalysts
close to
activity.
are shown in Table
[17, 21, 22, 251.
area was observed
crystallization sulfate
except
acidity
so far, the ZrO2 catalyst
as well as the highest
are much larger compared
treatment
in surface
at 5OO'C bears a surface we have synthesized
form
those of pure metal oxides
sulfate
treatment.
Among the superacids
Bl.
S042- a
500 650 800 575 650 525 600 525 550 600
that the catalyst
Ho=-13
(m2/g1
form; the pattern
coincident
of the
with that of Zr02
at 650°C.
Figure
6 shows the spectra
phase transformation by calcination.
of the TiO2-I
catalysts
[171.
of Ti02 is known to be from an anatase
It is seen that the temperature
The crystallographic form to a rutile one
of crystallization
or phase
224
I
I
I
I
20
30
40
50
I
I
60
70
2 e/de@
Fig. 4.
XRD profiles of Sn02 (A) and SO,/SnO, (B) calcined at 500'~
11 30
40
2 er'des
50
30
40
53
2wN
Fig. 5. XRD profiles of S04/Zr02-I and ZrOa-I. Calcination temperature: (A) 500°C, (B) 650°C, CC!)8OO'C.
225 transformation
of anatase
to r-utile form for S04/Ti02-I
that for pure Ti02; the pattern the TiOZ catalysts, The measurement
was pure anatase by scanning
the pictures
performed;
with the sulfate
well as the retardation
sulfate
microscope
than
of crystallization,
was
It is seen that the samples
into fine particles
the sulfate
Catalysts
of the Zr02
treatment.
in comparison
with
This must be a reason,
why specific
as
surface areas of the
are much larger than those of the oxides which have not undergone
the
treatment.
Specific
surface
the oxides without were prepared obtained one.
were cracked
without
is ~a. 2OO'C higher
at 525'C. most active among
system.
electron
are shown in Fig. 7 [161.
treatment
those of the substaces
catalysts
of S04/Ti02 -I treated
areas of the Al203 catalysts the sulfate
by the treatment
It is considered
after the treatment preparation
treatment
from the crystallized
on the crystallized
and highly active
than those of
These catalysts
as shown in Table IV.
oxides,
catalysts
on the surface
about by the different
method
area before and
of catalyst
[251.
TiO,-I
were
oxide rather than the amorphous
that the large difference
was brought
were much smaller
sO,/TiO,-I
(B)
L
2 e/des
Fig. 6. XRD profiles of S04/Ti02-I and Ti02-I. (A) 300°C, (B) 500°C, (C) 525°C. (D) 6OO'C.
Calcination
temperature:
226
(B)
(A) Fig. I.
AEM pictures
CATALYTIC
REACTIONS
of Zr02-I
BY SULFATE-METAL
About ten years have passed but the applications summarizes
in the consecutive suppress
a low temperature converted neopentane
of isopentane
the reaction
butane,
(2,2-dimethylpropane)
In esterification, used catalyst
on sulfated
+ isopentane + isobutane
should be carried
using a highly
into propane,
as catalysts
in the vapor phase,
steps of pentane
the reaction
selectively,
repeating
was examined;
at 650°C.
since this study began to be taken up seriously,
reactions
of pentane
(B) calcined
OXIDES
of solid superacids
the acid-catalyzed
In the reaction
(Al and S04/Zr02-I
the reaction
no reactivation
+ isobutane. for obtaining
1401.
pentane,
into methane,
Table V
metal oxides.
the reaction
is known to occur Thus, in order to better
out with a short contact
acidic catalyst isobutane,
are still few.
Cyclopentane
and isopentane,
ethane,
of ethanol
and propane
isopentane time and at was while
[171.
with acetic acid with the
of the ZrO2 catalyst
was needed
since
227 Reactions
Table V.
catalyzed
by solid superacids. References
Catalyst SO41"eOx
Reaction
Type of reaction
Zr02 Pentane 3 i-Pentane Isomerization zro2 Alkylation Methane + Ethylene 3 C3-C7 hydrocarbons 2rO2 i-Butane + Butenes +C5-Cl1 alkylates ZrO, o-Xylene + Styrene += Phenylxylylethane Toluene + PhCOCl + o-, m-, pAcylation Methylbenzophenone + HCl Toluene + (PhCO)20 + A1203, Zr02 Methylbenzophenones + PhCOOH zro2 Toluene + PhCOOH + Methylbenzophenones f H20 zro2 Toluene + CH3COOH + Methylacetophenones + H20 ZrO2 Chlorobenzene + o-Chlorobenzoyl chloride Esterification cl-~C4-0H + CH3COOH *Esters ZrO2 TiO2, Zr02 n-Octyl, 2-Ethylhexyl alcohol + Phthalic acid + Terephthalic, Ethanol + Acrylic acid -5 Ti.02, ZrO2 Methanol
+ Salicylic
acid +
Ethyl, Methyl vinyl ether _) Poly(ethy1, methyl vinyl ether) Butane, i-Butane + CO + CO2 Ethylene + A20 + Acetaldehyde + Acetone Cyclohexanol * Cyclohexanone
the catalytic However,
activity
remained
the TiO2 catalyst alcohol
the activity
because
of ZrO2 remaining
elimination
[47, 481.
between
Ti.02 and Zr02 catalysts at a high temperature
The Fe203 superacid hydrocarbons loo"c.
unchanged
for the repeated
The discrepancy
is 150°C, and it is considered
gave a 29% conversion
superacid
of oxidation [21, 221.
thus those superacids
operation
in the preparation
was found to be quite effective
by the sulfate
for the reaction
addition
the of
that the catalyst
of
at temperatures of butane
above
at 300°C to
where none of the reactions
treatment
1531.
was also observed
catalysts
without
as solid catalyst.
Iron and tin oxides are known to be oxidation would be the oxidation
acid
temperature
for oxidation
was performed
the sulfate
[501.
of phthalic
ion on the surface,
is more stable and effective
at 3OO'C over Fe203, without
enhancement
operation
of sulfate
form CO and CO2 in the ratio 4:6 under the conditions occurred
53 22 22
by the esterification
to CO and CO2 when the reaction
The catalyst
Fe203
for the repeated
of the elimination
sulfate
prepared
unchanged
was deactivated
with n-octyl
50 47, 48 51 47, 48 51 47, 48 51 52
TiO2, ZrO2
Polymerization Oxidation
40 41 42 43 25, 44 45, 46 25, 47 48, 49 47, 48 49 47, 48 49 45, 46
The activity with the Sn02 catalysts;
with superacidity.
STRUCTURE
OF ACID CENTERS
Experiments property; spectra
OF SULFATE-METAL
using XPS were carried
the spectra
OXIDES
out in order to elucidate
of the ZrO2 catalyst
are shown in Fig. 8 [54, 551.
of Zr 3d3/2, Zr 345/2, and 0 1s for S04/Zr02
consistent
with those for Zr02, 184.1,
(B. E.), respectively. which was similar
The former
treated
182.0, and 530.3 eV for binding
to that of Zr(S04)2.
is composed
peak
energy
at 532 eV,
The single peak of S 2p3/2 was observed Thus, it is concluded
of Zr02 and S04, not of Zr(S04j2.
On the other hand, the XPS spectra
of the Ti02 catalyst
be composed
of Ti02 and Ti(S04J2
XPS spectra
also showed the possibility
surface
The
at 65O'C were
sample also showed a shoulder
at 169.3 eV, whose value agreed with that of Zr(S04)2. that the surface
the surface
[561.
showed the surface to
In the case of the A1203 of bearing
superacid,
A1203 and A12(S04j3
the
on the
as is shown in Fig. 9 [251.
The IR spectra The samples
of the superacids
showed the spectra
of Zr02, Ti02, and Sn02 are shown in Fig. 10.
different
from those of metal
sulfates
(shown in
Fig. 2); all the materials showed absorption bands at 980-990, 1040, 1130-1150, and 1210-1230 cm -1 , which are assigned to the bidentate sulfate coordinated to metal
elements
[571.
The IR spectra conversion analogous between
of pyridine
examined;
on S04/Zr02-I(650°C)
showed the easy
of Lewis sites to Brb'nsted sites by water molecules results
were also observed
the preheating
reaction
adsorbed
conditions
temperature
before
the results
when heated
with the Ti02 superacid
of S04/Zr02
reaction
that Bransted
sites, were decreased thus the reaction the activities
on heating
by regeneration
sites, created
by heating
of butane
decreased
at the high temperatures
catalyzed
activity
by heating
by adsorption
The relation
under the pulse
for the reaction
The maximum
are shown in Fig. 11.
at 350°C, and the activities
It is considered
in a reactor
and activity
of butane was was observed
at 400 to 6OO'C.
of water on Lewis
in the He flow, and
by Briinsted acid was restrained.
at 500 and 55O'C were raised to those around
of the Brb'nsted sites
(A' and B' in the Figure),
was treated
followed
by heating
again in the He flow at 3OO'C for 1 h and performing
reaction
at 13O'C.
It is indicative
are easily
the reaction
Brhsted
changeable
of butane
acid
In fact, 300-4OO'C
where the
catalyst
catalysts
by moistening
The
[54, 551. [161.
with water at 12O'C after the reaction,
that Lewis and BrGnsted
by adsorption
being also catalyzed
or desorption
of water molecules,
by Brijnsted sites
site Lewis
acid
the
sites on the present
site
[54, 551.
229
Zr 3d3/2, 512
0 Is
(A)
(B)
(C)
1111(111111( 534
530
526
186
182
178
Binding energy, eV Fig. (Cl:
8. XPS spectra of ZrOZ ZrOZ-I (650'12).
catalysts.
(A):
Zr(S04j2,
Al 2~
0 1s
A
(A)
_I 540
535 eV
530
525
80
75 eV
70
Blndina energy
Fig.
9.
XPS
spectra
of Al,(SO,),
(A) and
S0,/A1203
(B).
(B):
S04/Zr02-I
(65O"C),
230
1300
1500
1100
900
Nave number, CB-~ Fig. 10. IR spectra of SO4/ZrO -1 (650°C) (A), SO4/Zr02-I S04/TiO2-I (525°C) CC), and SO4 3SnO2 (55O*C) CD).
From the above results, with Zr elements
in the bridging
the case of titanium the complex
is much stronger
present,
iron oxide
is a chelating
studied
in the absence whereas
in the presence
thus accounting spectroscopic 1651.
of sulfated
sulfate:
thus,
by the inductive
If water molecules
by IR spectroscopy
alumina
and titania
are
117, 55, 601.
suggested
161-631.
1641.
Saur and
and postulated
are bonded
to a bridged
Brijnsted acidity zirconia
in
of acid sites on sulfur- promoted
of H20 this is converted
of sulfated
et al. proposed
to Brijnsted acid sites
three oxygens of the sulfate
for the increased studies
complex
remarkably
by arrows.
that the structure
the structure of water,
to be SO4 combined
with that of a simple metal stronger
fBl,
The double bond nature of
ion 158, 591.
as illustrated
hidentate
appears
state as Okazaki
the Lewis acid sites are converted
Tanabe et al. proposed
others
compared
of Zr4' becomes
of S=O in the complex
structure
bidentate
oxide with sulfate
the Lewis acid strength effect
the surface
(8OO'C)
that,
to Al or Ti,
bidentate
Recent
a monodentate
sulfate,
laser Raman structure
231
Heating temperature of catalyst, "C Fig. 11. Catalytic activities of S04/Zr02-I (65O'C) preheated at various temperatures in a He flow before reaction (butane at 130°C). (0 ): Heat-treated (0): Exposed to water by injection at 12O'C and treated at various temperature. at various temperatures. A', B': After the reaction of butane (A, B), water (lull was injected at 12O'C followed by heating the catalyst at 3OOOC for 1 h and performing the reaction under the same conditions.
SUPERACIDS
BY METAL OXIDES
Although elevated
the sulfate
temperatures
THEMSELVES
superacids
the system of metal oxides. containing
any sulfate
temperatures
ammonium drying,
metatungstate
observed
anhydride
both reactions.
estimated
not
which can be used at
Zr(OHj4 was impregnated followed
method
with aqueous
by evaporating
The concentration
13 wt.% W after calcination
were quite effective
with tungstic
water,
was 15 wt.% W
at 650-950°C.
for the benzoylation
and for the reaction
of pentane;
at the surprisingly
The SiO2-A1203
The catalyst
at 50°C and for pentane on ZrO2
as follows.
[(NH,)6iH2W12040)-"H201
with calcination
conditions.
type of superacid,
at
with
The analogous
acid
(H2W04) which
in water.
The catalysts benzoic
superacids
[66-691.
was also formed by the kneading
is insoluble
another
of metal oxides,
in air at 600-1OOO'C.
based on the hydroxide, superacid
We have prepared
was prepared
and calcining
of heat-treatment
it is hoped to synthesize
ion but consisting
of over 800°C
The catalyst
are stable enough because
for preparation,
catalyst
treated
of toluene
the maximum
high temperatures
was totally
inactive
at 800°C was active
to be Has-14.52
166, 671.
The acid strength
by a color change method
was
of 800-85O'C
for
under the same
for isomerization
at 30"~‘ and XPS showed this catalyst
IW03/~r02(800~C11
with
activity
of butane
to be WO3 supported
of this catalyst
using Hammett
was
indicators.
232
I
I
I
I
I
40
20
60
26 /dea
(B): W03/Zr02 (A): W03 (700'C). Fig. 12. XRD profiles of W03/Zr02 catalysts. (800°C). (Cl: wo3/zro2 (1000"c). (D): W03/Zr02 prepared by calcining Zr(OHj4 at 700°C, impregnating with the tungstate and calcining at 7OO'C.
The catalysts
prepared
with the tungstate activities,
and finally
the spectra
precalcining
Zr(OHj4
to 800-85O'C
to be a monoclinic
W03 (D), while the materials
with that of the latter material
by impregnation calcination combines
calcined
then converts
system
from the inactive
similarly
prepared
coincident
CC), whose catalytic
activity
sites are not created form whose
form; i.e. tungsten
superacid
oxide
sites at the time when a
In fact, the appearance
material
of W03 from 600
of the former was almost
it to the crystalline
at
to the
from Zr(OHj4 dried
the crystallization
that superacid
was
by
and calcining
oxide, but on the amorphous
oxide to create
is formed.
prepared
in addition
at 1OOO'C
it is concluded
on the crystallized
with zirconium
tetragonal greatly
Therefore,
at
of Zr02, as was
by impregnating
prepared
forms without
of Zr(OH)4
of the catalysts
The catalyst
system
(B); the pattern
of calcination
low.
temperature
each
the same
by calcination
XRD measurement
at 7OO'C to Zr02 followed
at 1OO'C gave 100% tetragonal
was quite
greatly
are shown in Fig. 12.
700°C showed the pattern crystallized
superacids.
then impregnating
at 8OO'C gave almost
decreased
of over 4OO"C, the crystallization
with the sulfated
performed;
at 100-300°C,
Zr(OH)4
calcining
while the activities
temperatures observed
by heating
of the catalyst
from the crystallized
differs
oxide as shown
233
CD)
(B)
(A)
Fig. 13. Pictures of WO,/ZrO, catalysts. (B): WO, prepared (A): ZrO, (800°C). at 8OO'C. by calcining ammonium me
in Fig. 13.
(C) is white in color, W03 being highly dispersed
The former
the Zr02 lattice, WO3 itself
whereas
the latter
[16, 661.
This catalyst
preparation
impregnated
with molybdic
evaporating
water,
method
acid
drying,
benzoylation
of toluene
Si02-A1203;
by the visual
considered
Superacid crystallized catalyst.
sites were not created
by
was 5 wt.% MO
for the
at 750-800°C.
the acid strength
of the Hammett
Since the
was not
indicators.
higher
It is
than Ho=-12.70
with those of Moo3 and Zr02
material
different
(c_a. at
[16, 681.
of the molybdate
as was oberved
of the inactive
was
followed
which did not occur over
by impregnation
oxide was also completely
Zr(OH)4
XPS spectra of the sample treated
were consistent
The XRD pattern
The concentration
bears a surface acidity results.
oxide; ammonia
was effective
on calcination
green),
oxide, but on the hydroxide
crystallized hydroxide
anhydride,
(yellowish
in aqueous
in air.
color change method
from the reaction
[Mo03/Zr02(8000C)1
to molybdenum
The catalyst
were observed
that the catalyst
-13) judging 800°C
[681.
with benzoic
high activities
was itself colored
estimated
was applied
(H2M004) dissolved
and calcining
metal based on the hydroxide
catalyst
into
(D) is not, the color being close to that of
on the
in the case of the W03
prepared
from the
from that prepared
from the
as shown in Fig. 14 [681.
Molybdenum the present
oxide
is well known to be one of the oxidation
substance
would be an oxidation
catalyst
catalysts,
with superacidity
and thus whose new
234
I
I
20
I
I 40
I
I
60
2e/deg Fig. 14. XRD profiles of Mo03/Zr02 catalysts. (A): MoO3/ZrO2 prepared by impregnation of the molybdate on the crystallized 2x-02 (calcined at 7OO'C) followed by calcination at EOO'C. (B): Mo03/Zr02 (8OO'C).
Table VI.
Surface
areas of W03/Zr02
Surface W03/Zr02
Calcination temp ("C)
100 800 850 900 1000
is expected.
1.2% CO, 98% selectivity at 500-7OO'C surface
It is noteworthy
with the sulfate
The catalyst
was inactive
converted
2
methanol
catalyst
tungsten
by calcining
especially
shown to contain
acidity,
is strongly
and an excess of the sulfate
prepared
at 800°C.
by calcination
This value is estimated interacted
is decomposed
while calcining
with
oxides as was just observed
in the case of calcination
2.2 wt.% of S.
the amount of sulfur which as sulfate
are shown in Table VI.
are much larger compared
and molybdenum
with the highest
fact, fuming gas is observed
into 68% HCHO and
oxide prepared
areas of the W03 and Moo3 catalysts
superacids,
650°C, was already
34 15 6
[691.
that the areas of both catalysts
The S04/Zr02-I
Zr02
68 60 58 43 7
for HCHO, while molybdenum
those of the oxides without
monolayer,
area (m2/g) Mo03/Zr02
30 12
catalytic-action
Specific
catalysts.
44 39 35
600
H2Mo04
and MoO3/ZrO2
to be
with Zr02 in a
to form sulfur oxides.
the catalyst.
at
2.2 wt.% of S is
In
235
to 13 wt.% of W and 6.6 wt.% of MO, these values being
equivalent
the supported excess
quantities
of molybdenum
of the present
Sublimation
catalysts.
oxide was also observed
with calcination
just equal to
based on an
of the Moo3
catalyst. CONCLUSION
AND PROSPECTS
I have attempted
to present
and their catalytic
action,
Solid acid systems
stronger
the recent works on syntheses
together
as solid superacids.
Sulfate-supported
observed
metal oxides were stable because
Another
being
satisfactory
extensively
liquids
catalyst.
will undoubtedly
superacids
tungsten
by a new preparation
to other metal oxides
There are many reactions as an effective
of heat-treatment
in which
with the oxide
its stability
method
will be
for new solid superacids.
solid superacid
The convenience provide
at high
or molybdenum
method,
It is hoped that the preparation
so far.
applied
and are
of the sulfate was sometimes
type of superacid,
was prepared
on zirconia,
structure.
which were used
recently
thus it was hoped to synthesize
reaction,
system of metal oxides. supported
but elimination
for preparation,
during
and zeolites,
in the past, have been developed
as catalysts
categorized
temperatures
with some view of the surface
than silica-alumina
extensively
of solid superacids
might be expected
to perform
of using solids in place of corrosive
an incentive
to further
studies
in the use of
solid superacids.
REFERENCES 1
R. J. Gillespie,
2
R. J. Gillespie
&
Chem. Res, 1 (1968) 202. --
and T. E. Peel, Adv. Phys. Org. Chem., 2 (1972) 1.
3
G. A. Olah, G. K. S. Prakash,
and J. Sommer, I_ Science
4
G. A. Olah, G. K. S. Prakash,
and J. Sommer,
206 (1979) 13.
Superacids,
Wiley,
New York, 1985. 5
M. Hino and K. Arata,
6
T. Takeshita,
Chem. L&t.,
K. Arata,
(1979) 1259.
T. Sano, and K. Tanabe,
Kogyo Kaqaku
Zasshi,
69 (1966) 916. 7
K. Arata,
T. Takeshita, N. Azumi,
and K. Tanabe,
8
K. Arata,
9
K. Arata and I. Toyoshima,
Chem. -*n Lett _
10
K. Arata and I. Toyoshoma,
Shokubai,
11
K. Arata, K. Sato, and I. Toyoshima,
12. K. Arata,
and H. Sawamura,
u
Shokubai,
Chem. Sot. s., --
13
K. Yabe, K. Arata,
M. Hino and K. Arata,
and I. Toyoshima, Shokubai,
15
M. Hino and K. Arata,
Chem. Lett.
48
(1975) 2944.
(1974) 929. 17 (1975) 98P. J- /* Catal
K. Yabe, M. Hino, and I. Toyoshima,
14
8 (1966) 226.
42
(1976) 221.
Shokubai,
19 (1977) 246.
J. Catal., 57 (1979) 231.
-21 (1979) 217. (1979) 477.
236
16
M. Hino and K. Arata,
17
M. Hino, Ph.D. Thesis,
18
M. Hino and K. Arata, J- Chem. &
Chem. Commun.,
19
M. Hino, S. Kobayashi,
J. Am. --Chem. Sot., 101 (1979) 6439.
20
M. Hino and K. Arata, J- Chem. Sot., Chem. Commun.,
21
H. Matsuhashi,
M. Hino, and K. Arata,
22
H. Matsuhashi,
M. Hino, and K. Arata, Appl.
23
H. Matsuhashi,
M. Hino, and K. Arata, Hokkaido
Society
of Japan,
unpublished Hokkaido
data.
University,
and K. Arata,
Abstr.
Hokkaido,
Chem. e.,
Japan,
1982.
(1979) 1148.
(1980) 851. (1988) 1027.
Catal.,
z
(1990) 205.
Summer Meetinq
No. E15, 1989. _25 (1984) 143.
24
K. Arata and M. Hino, A-React
25
K. Arata and M. Hino, Appl. Catal.,
59 (1990) 197.
26
K. Arata, M. Hino, and N. Yamagata,
Bull. Chem. Sot. Jpn.. 63
27
M. Hino and K. Arata, -J. Chem. Sot., Chem. Commun.,
28
M. Hino and K. Arata, -Chem. Lett.,
Kinet. Catal. E.,
K. Arata and M. Hino, Shokubai,
30
M. Hino and K. Arata, _Ad--.# J. Chem
31
M. Hino and K. Arata, -J. Chem. Sot., Chem. Commun.,
32
s. Baba, Y. Shibata,
33
Abstr. 34
35
T.
and K. Kohsaka,
Japan Pat.
T. Imai, and N. Yokoyama, Nagoya,
16th National
October
1986,
p. 68.
Imai,
Nojima,
S.
T. Shimizu,
Society of Japan,
K. Arata,
in Shokubai
and S. Baba, 9
Sendai,
Kohza,
September
ed.by Catal.
National
Meetinq
Of the
1988, Abstr. NO. 3B307.
Sot. Japan, Kodansha
Scientific,
(19861, Vol. 11, p. 31.
36
K. Arata and M. Hino, Shokubai,
37
K. Tanabe,
in J. R. Anderson
K. Tanabe
-24 (1982) 241
and M. Boudart
Vol. 2, Springer-Verlag
Technoloqy, 38
(1988) 1168.
(1986).
Society of Japan,
Catalysis
Tokyo
(1987) 1355.
Chem. Commun
T. Kimura,
68138
H. Takaoka,
of the Petroleum --
(1984) 1037.
28 (1986) 413. Sot
H. Takaoka,
s. Baba, T. Shimizu, Meetinq
(1990) 244.
(1985) 1483.
29
(Toku Kai Shou) 61-68137,
of the Chemical ---
and R. Noyori,
Berlin,
(eds.), Catalysis-Science
Superacid-Superbase,
and
New York, 1981.
Heidelberg, Kodansha
Scientific,
Tokyo.
1980, p. 5. 39
J. Livage,
40
M. Hino and
K. Doi, and C. Mazieres,
41
M. S. Scurrell,
42
K.
K.
Hatakeyama,
Petroleum
Arata, d React
Kinet A-
Appl. Catal., 2 T. Suzuka,
R. A. Rajadhyaksha
44
K. Arata and M. Hino, National
45
T. Yamaguchi Irkutsk,
_19 (1982) 101.
and H. Ozaki, 28th National
43
October
SOC., 2
Catal. a.,
(1968) 349.
(1987) 109.
Society of Japan, Akita,
Hamamatsu,
J. Am. Ceram.
Meetinq
of the
July 1986, Abstr. NO. 38.
and D. D. Chaudhari, Meetinq
Ind. Eng. Chem. Res.. 26 (1987) 1743. of the Catalysis
Society of Japan,
1984, Abstr. NO. C37.
and K. Tanabe,
p. 20, 1983.
Proceed.
_7th Soviet-Japanese
Seminar _--*t
on Catal
237
T. Yamaguchi,
K. Akiyama,
46
K. Tanabe,
47
K. Arata and M. Hino, Shokubai,
48
K. Arata and M. Hino, Proceed.
Proceed.
Irkutsk,
8th Int. Gong.
Catal.,
A. Mitoh,
K. Iwabuchi,
and K. Isogai,
1984, p. v-601.
Berlin(West), 25 (1983) 124.
-7th Soviet-Japanese
Seminar
on Catal.,
p_ 7, 1983.
49
J. Chem. Sot M. Hino and K. Arata, _--J-d'
50
M. Hino and K. Arata,
51
M. Hino and K. Arata, Appl.
Chem. Commun
Chem. E.,
(1985) 112.
(1981) 1671.
$j
Catal.,
(1985) 401.
(1980) 963.
Chem. s.,
52
M. Hino and K. Arata,
53
M. Hino, S. Kobayashi,
54
M. Hino, K. Arata,
55
K. Arata and M. Hino, Hyomen, 19
(1981) 75.
56
M. Hino and K. Arata,
(1990) 481.
57
K. Nakamoto,
58
A. Kurosaki
59
S. Okazaki,
60
K. Tanabe,
and K. Arata, _A----React. Kinet
18 (1981)
Catal. Lett
491. and K. Yabe, Shokubai,
Hyomen, 28,
J. Fujita,
S. Tanaka,
-22 (1980) 232.
and M. Kobayashi,
J- --Am. Chem. SOC., 79
(1957) 4904. and S. Okazaki, T. Chinone, Proceed.
Texas A & M Univ., 61
T. Jin, M. Machida,
Nippon Kagaku
and A. Kurosaki,
-2nd Symposium College
(1976) 1816.
Nippon Kaqaku
Ind.-Univ.
Station,
T. Yamaguchi,
kaishi,
Kaishi,
Cooperation
(1977) 1282.
Chem. PToq.,
TX, 1984, p. 71.
and K. Tanabe,
Inorg. Chem.,
23
(1984)
4396. 62
T.
Yamaguchi,
63
T.
Jin, T. Yamaguchi,
T. Jin, and K. Tanabe, and K. Tanabe,
J. Phys. -Chem.,
64
0.
Saur, M. Bensitel,
A. B. Mohammed
Saad, J. C. Lavalley,
B. A. Morrow,
J. Catal.,
99
65
K. Hatakeyama
and T. Hisamitsu,
66
K. Arata and M. Hino, Proceed.
J. Phys. Chem., 90 (1986) 3148. 90 (1986) 4794. C. P. Tripp,
and
(1986) 104. unpublished
data.
9th Int. Gong. --
Catal.,
Calgary,
Canada,
P- 1721. 67
M. Hino and K. Arata, -J. Chem. a
68
M. Hino and K. Arata,
69
K. Arata and M. Hino, Shokubai,
Chem. _*I Commun -
Chem. E.,
(1989) 971.
11
(1989) 477.
(1988) 1259.
1988,