- Email: [email protected]
Rapid synthesis of zeolite catalysts for methanol to olefin conversion by the precursor heating method
,187
Applied Catalysis, 8 (1983) 187-197 Elsevier Science Publishers B.V., Amsterdam -Printed
RAPID SYNTHESIS PRECURSOR
OF ZEOLITE
HEATING
Tomoyuki
CATALYSTS
FOR METHANOL
TO OLEFIN
CONVERSION
BY THE
METHOD
INUI, Noriko MORINAGA
Department
in The Netherlands
of Hydrocarbon
and Yoshinobu
Chemistry,
Sakyo-ku,
Kyoto 606, Japan.
(Received
15 December
1982, accepted
Faculty
TAKEGAMI of Engineering,
10 August
Kyoto
University,
1983)
ABSTRACT Rapid synthesis of a zeolite which has catalytic activity for methanol conversion into C2%C4 olefins with high selectivity has been studied. Firstly, the crystallization of ZSM-34 class zeolite, using choline as the organic ingredient at 100°C for 131 days (standard method) has been followed by measurements of XRD, SEM, BET surface area and catalytic activity. An amorphous precursor of spherical shape was formed from the gel mixture within three days and intergrowth of zeolite crystals occurred in the spherical precursor. Optimum selectivity for olefin formation was obtained with a zeolite crystallized over 25 days. In order to reduce the crystallization time, we tried heating directly the gel at a constant rate of 2.8"C min-1 to 200°C and maintaining it at this temperature for 2 h (direct heating method). However, the catalyst life for methanol conversion was shortened. On the other hand, when the precursor was heated at a constant rate of 1.7"C min-i to 190°C and maintained at this temperature for 0.5 h (precursor heating method), the resulting zeolite exhibited a better performance than zeolites prepared by the standard and direct heating methods.
INTRODUCTION Shape selective extensively
zeolites
studied.
such as ZSM-5 [I,21 and ZSM-34
Particular
catalysts
because
synthesis
from methanol.
interest
of their excellent
has been paid to these new types of
selectivity
larly in ZSM-34 preparation
which
during
performance
catalytic
of the crystals
A reduction
performance
their preparation
and low efficiency
In this study, we have firstly investigated synthesis.
or lower olefin
procedures,
particu-
takes 25 to 196 days at 100°C. Long crystalliz-
ation times may give low reproducibility
zeolite
for gasoline
In general, however, these shape selective zeolites need
a very long time for crystallization
the catalytic
[3,4] have been
the change formed during
in crystallization
in zeolite
in physical
synthesis.
properties
and
the course of ZSM-34 class
time without
damage
to the
was achieved.
EXPERIMENTAL Standard
method
Preparation
of zeolite
Mobil Oil Co. However, 0166-9834/83/$03.00
preparation
of ZSM-34 class zeolite was based on the patent choline
literature
[5-71 was used instead of choline
0 1983 Elsevier Science Publishers B.V.
chloride
[4] of as the
188 organic
amine ingredient,
because
prepared with the use of choline from methanol
it has been confirmed
used were 30 wt% silica sol solution,
reagent grade sodium and potassium water.
sodium aluminate the choline container,
for olefin
synthesis
than zeolite which was prepared with the use of choline
The reaction materials
distilled
that zeolite which was
has a better performance
Appropriate
hydroxides,
amounts
solution,
50 wtX choline
of sodium hydroxide,
were added to the distilled the mixed aqueous
chloride.
sodium aluminate, solution
potassium
and
hydroxide
water and were dissolved.
solution
was kept at 0°C. In another
the silica sol solution was also made at 0°C. The two solutions
mixed quickly
and stirred vigorously
for 2 min using a Homo-Mixer
Kogyo Co.). The gel solution mixtures for various
were crystallized
at 54O'C for 3.5 h. The molar
in the results and discussion
with
under passage of air
(Na + K)/Al, K/(Na + K), choline/OH-
were fixed at 9.3, 7.3, 0.17 and 0.67, respectively. described
Kako
at 100°C in a thermostat
at lOO"C, then calcined
ratio of Si/Al,
were
(Tokushuki
periods from 0.25 to 131 days. The solid products were washed
water to pH = 9 and dried overnight
and
After adding
The improved method will be
section.
Characterization X-ray powder diffraction
patterns
(XRD) of the synthesized
using a Rigaku Denki Geigerflex-
with Ni-filtered
The size and shape of the samples were observed electron microscope
(SEM) MSM-102.
coated with a Au evaporated etrically method
measured
apparatus
Methanol
conversion
internal diameter.
was carried
was measured
pressure.
and 88 ~01% N2, was allowed
conversion
RESULTS Change
at the entrance
gas mixture,
products
About
reactor of 4.8 mm bed
of the catalyst
the catalyst was dried iri S~:ZL
flow. The reaction
The reaction
flow reactor.
tubular
heated and the catalyst
located
reaction,
to flow through
of 1000 h-l. The reaction
chromatograph
by the one point
TG-20.
out using a conventional
by a thermocouple
at 500°C for 0.5 h under a nitrogen
velocity
temperature
analyzer
was placed in a quartz
The reactor was electrically
bed. Prior to the methanol
under atmospheric
scanning
on brass pegs and
and procedure
150 mg (0.22 ml) of catalyst
temperature
CuKu radiation.
areas of the samples were gravim-
at liquid nitrogen
using a Shimadzu microthermogravimetric
Reaction
monochromatic
with a Hitachi-Akashi
The samples were mounted
film. BET surface
by N2 adsorption
samples were recorded
was carried composed
the catalyst were analyzed
out at 400°C
of 12 ~01% methanol
bed at a gas hourly space using a Yanagimoto
G 80 with a column of X-28.
AND DISCUSSION in properties
standard
preparation
The change
and catalytic
activity
with crystallization
time for the
method
in crystal
shape with crystallization
time at 100°C is shown in
gas
189
'IGURE 1
SEM micrographs
leriods by the standard
of the zeolites preparation
crystallites
method.
crystallized
for diff 'erent
190 Figure
1. The gel mixture
was converted
The shape and size of the spherical that the particles of XRD patterns
into spherical
particles
became larger and square.
for the zeolites
were maintained
crystallization
at 0.5 and 1 day show very poor crystallininty,
16 day sample were generated
XRD patterns catalysts
of ZSM-34
appeared.
hydrocarbons.
The catalytic
has the highest
activity
is expressed
particle
formation
increased
decreased.
products
selectivity
period corresponds
formation
yield
(DME) and C,%C5 by propylene
formed
[83. The
(STY) of DME and propylene. the BET surface
to the period of spherical
After 3 days, the BET surfcae
approached
increased
ether
and sharply, whereas
This period corresponds
sharply and then gradually
a highest
with decreasing
to the period of intergrowth
1/2dry
time
and different
are represented
among hydrocarbons
by the space-time
from the gel mixture.
this trend, propylene
shown by the 16
and BET surface areas of these
were dimethyl
In the first 3 days, DME was formed exclusively area of the catalyst
shown in the
[4]. When the crystallization
activities
In Figure 3, the hydrocarbon
since propylene catalytic
structures
of these XRD lines weakened
are shown in Figure 3. The products
intensities
time. The samples
but the sample at three days shows
to the main crystal
was very long (131 days), the intensity
3 days.
for 8 days, but after
in less than 3 days. The XRD pattern
day sample is like the XRD patterns
within
Figure 2 shows relative
of different
that the XRD lines which correspond
particles
level.
area
In concert with
DME formation.
of the zeolite crystal
This
in each
Bday
I
lbday
0
10
20
30
40
50
,
I
60
0
10
28
FIGURE 2
30
40
1
50
60
28
X-ray diffraction
periods by the standard
20
patterns
preparation
of the zeolites method.
crystallized
for different
191
Crystallization time (day)
FIGURE 3
Effects of crystallization
and specific
surface
spherical
particle.
paraffin
selectivity
the highest
gel mixture zeolite
After a very long crystallization increased
selectivity
occurs
selectivity
to olefin formation
particle
time suggests
with the zeolite
The most surprising
which
material,
surface
prepared
observation
of
and the change
is the precursor
in BET surface
crystallinity.
time, we firstly
of the
area. The crystallization
that the rate of crystallization
early stage but slows down with increasing
200°C as described
Consequently,
is that in the period of the first 3 days all the
and has very little internal
reduce the.crystallization
time, such as 131 days, decreased.
was obtained
1 month.
into the spherical
in each spherical
crystallization
and olefin
time of about
experiments
converted
crystal
activities
areas.
with a crystallization these sequential
time at 100°C on the catalytic
tried heating
area with is rapid in the
Therefore,
in order to
the gel directly
to
below.
Direct heating method The composition as described
of the solution
in the experimental
OH-. The molar
mixtures
section,
ratio of choline/OH-
was reduced
i.e. 0.26, because when the gel mixture was heated directly organic placed
ingredient
to 2OO"C,
the resulting
catalyst.
zeolite activity
as the standard
preparation
method
by the standard
crystals
contained
method
much
and life [S]. The gel was heating
for 2 h. The synthesized
Figure 4 shows the SEM photograph
was the same
ratio of choline/
to ea. l/3 of the standard method,
and was heated at a constant
to 200°C and then was maintained the same manner
for the molar
which was prepared
and gave poor catalytic
in an autoclave
for the gel preparation
except
rate of 2.8"C min
material
mentioned
and the relative
-1
was treated
above to provide intensities
in the
of the
192
0
I
I
I
I
I
IO
20
30
40
50
I 60
28 (b)
FIGURE 4
(a) SEM micrograph
crystallized
and (b) X-ray diffraction
by the direct heating method.
pattern of the zeolite
193 XRD pattern zeolite
for the zeolite.
prepared
crystals
formation activity zeolite
by the standard
were observed.
of the zeolite
prepared
reduction
Precursor
for methanol
suggesting
conversion
prepared
temperature
structure
by the standard
time would
or catalytic
preparation
occurred
The method
of gel preparation
except the molar
standard
preparation
formation,
without
was the same as described
a considerable
essential
change
in
The gel solution
formation.
to autoclaves
mixtures
The precursor
and the temperature
level for 0.5 h. For reference,
the precursor
were also treated
preparation
with different
method.
The change
crystallization
with the mothor
The crystallinity smaller
of the precursor
than that of the precursor
(Figure 2, 3 days),
probably
of the spherical
5a. The XRD patterns
liquor was
shape and XRD for these samples 5 and 6, respectively.
in the XRD patterns of the standard
(Figure 6a) was
preparation
of sodalite
precursor
was satisfactory,
(Figure 2, 5 days). crystals
conditions
of 160°C and
for the zeolites
crystals
are suggested
prepared
was carried
out on each catalyst
time yields
of products
crystals.
crystallized
When the crystallization
temperature
increased
was raised to 220°C.
marks,
are
the needle shaped
method.
reaction The space-
areas of these samples
For the zeolites
temoerature
into needle
conversion
preparation
7. BET surface
temper-
at 220°C. XRD patterns
The methanol
from the modified
to ca. l/IO and C2sC4 olefins
the crvstallization
transformed
increased
at 190 and 220°C. Therefore,
are shown in Figure
in this figure.
DME was the main product. DME decreased
were partially
from those of ZSM-34 with circular
to be sodalite
conditions
when the crystallization
and the number of these crystals
[9], distinguished
are superimposed
However,
However,
as can be seen from Figure
of the sample with crystallization
observed
method
due to the use of a smaller amount of choline.
ature was 19O"C, the spherical shaped crystals
at each
as the
0.5 h (Figure 6c) were the same as for the sample with crystallization of 100°C and 5 days
rate of
at 100°C for 29
in the same manner
are shown in Figures
reflected
at 100°C
was maintained
was crystallized
in crystal
conditions
is l/3 that of the
were maintained
was raised at a constant
days. The synthesized
materials
in the experimental
was 0.27, which
1.7"C min-' to 130, 160, 190 and 220°C and the temperature
formation
just
that if the
activity.
ratio of choline/OH-
method.
for 3 days for precursor transferred
somewhat
However,
It was thought
precursor
be expected
method.
early in the reaction,
heating method
section,
standard
C9]
1, the catalytic
was higher than that of the
method.
was raised after
square from that
that sodalite
As shown in Table
by carbon deposit
in crystallization
the zeolite
method,
for 25 days by the standard
as with the catalyst
shown in the
were not seen at all and uniform
by ZSM-34 formation.
of the catalyst
crystallization
which were typically
of the zeolite were also different
by the standard
of this zeolite crystallized
crystals
method
XRD patterns
was accompanied
deactivation
Spherical
at 130 and 16O"C, was raised to 19O"C,
dramatically. ethvlene
However. when
formation
decreased
method
astandard
31.8
39.0
21.6
28.2
C2=
'precursor heating method d total amounts of ali hydrocarbons
bdirect heating method
preparation
17.8
10.6
5.7
11.3
c1
100°C x 29 daysC
190°C x 0.5 hC
100°C x 3 days +
200°C x 2 hb
100°C x 25 daysa
conditions
35.8
25.2
35.2
43.0
C3=
0.4
3.8
4.5
1.5
C4
C4=
7.1
9.7
21.0
8.2
/mol%
prepared
1.35
2.02
1.27
1.18
began to decrease
5.4
4.0
6.5
4.7
c5<
/mol l-'
86.2
96.9
79.6
57.6
/%
MeOti conv.
methods.
ZHCd
by different
formed until MeOH conversion
1.7
7.7
5.5
3.1
C3
selectivity
of the zeolites
Hydrocarbon
and product distribution
Crystallization
Activities
TABLE 1
61.5
92.1
79.6
53.1
HC 1%
Conv. to
49.2
67.8
60.7
43.2
C2%C4,/%
Conv. to
24.7
4.8
0
4.5
DME /%
Conv. to
FIGURE 5
SEM micrographs
in the precursor
of the zeolites
heating method.
crystallized
(a) 100°C x 3 days,
under different
conditions
(b) 100°C x 3 days t 130°C x
0.5 h, (c) 100°C x 3 days + 160°C x 0.5 h, (d) 100°C x 3 days t 190°C x 0.5 h, (e) 100°C x 3 days + 220°C x 0.5 h.
196
(a)
k 10
0
20
(b)
30
40
50
60
28
FIGURE 6 conditions
X-ray diffraction in the precursor
patterns
of the zeolites
heating method.
crystallized
under different
(a) 100°C x 3 days,
(b) 100°C x 3 days
+ 130°C x 0.5 h, (c) 100°C x 3 days + 160°C x 0.5 h, (d) 100°C x 3 days + 190°C x 0.5 h, (e) 100°C x 3 days t 220°C x 0.5 h.
1.5
1.3
300 F
F ;
0.8
H
0.6
% 5
5
S .woM)c 5 :
0.4
k 0.2
0
1W 100
130
160
190
220
250
Jo
Crystallization temperature ("C)
FIGURE 7
Effects
on the catalytic 0,
C4H8; 0,
of crystallization activities
CH4; A,
temperature
and the specific
C3H8; n , C4H,0; 0,
in the precursor
surface
DME.
areas.
0,
heating method
C2H4; A
, C3H6;
197 markedly smaller
and DME increased.
than that of the 190°C sample.
the zeolite
crystallized
by the standard
mixture
attributed zeolite
catalyst
prepared
prepared
activity
was prepared
heating method,
by the standard
the olefin
time needed
reduced
by higher
to prepare temperature
heating method
(200DC,
selectivity method.
was lower than
The reason may be
On the other hand, with the heating method,
the
were higher than in the case of the and the direct
on the catalyst
1 h on stream was very small,
the crystallization significantly
method
crystallized
at 100°C for 29 days using the gel
preparation
selectivity
preparation
the carbon deposited
during
with the zeolites
at 190°C for 0.5 h in the precursor
and ethylene
by the standard
Moreover,
1 shows the product selectivity for
to the use of l/3 the amount of choline.
catalyst
catalytic
Table
(lOO°C, 25 days) and by the direct
catalyst
with the precursor
for the zeolite
area of the 220°C sample was markedly
at 190°C for 0.5 h compared
conditions
2 h). When the zeolite
method
The BET surface
prepared
indicating olefin
by the precursor long catalyst
selective
treatment
heating method. heating
life. Thus
zeolite could be
of the zeolite
precursor.
REFERENCES 1 2 3 4 5 6 7 8 9
S.L. Meisel, J.P. McCullough and C.H. Lechthaler, Chemtech, (1976) 86. Mobil Oil, U.S. Patent, 3,894,107 (1975). M.K. Rubin, E.J. Rosinski and C.J. Plank, U.S. Patent, 4,086,186 (1978). Mobil Oil Co., Jpn. Patent Application Disclosure, 58,499 (1978). T. Inui, E. Araki, T. Sezumi, T. Ishihara and Y. Takegami, React. Kinet. Catal., Lett, 18 (1981) 1. T. Inui, T. Ishihara and Y. Takegami, J.C.S. Chem. Comm., (1981) 936. T. Inui, T. Ishihara, N. Morinaga and Y. Takegami, React. Kinet. Catal. Lett., 19 (1982) 71. T. Inui, T. Ishihara, N. Morinaga, G. Takeuchi, E. Araki, T. Kanie and Y. Takegami, J. Chem. Sot. Japan., Chem. and Ind. Chem., (1982) 221. Ch. Baerlocher and W.M. Meier, Helv. Chim. Acta., 52 (1969) 1853.
Applied Catalysis, 8 (1983) 187-197 Elsevier Science Publishers B.V., Amsterdam -Printed
RAPID SYNTHESIS PRECURSOR
OF ZEOLITE
HEATING
Tomoyuki
CATALYSTS
FOR METHANOL
TO OLEFIN
CONVERSION
BY THE
METHOD
INUI, Noriko MORINAGA
Department
in The Netherlands
of Hydrocarbon
and Yoshinobu
Chemistry,
Sakyo-ku,
Kyoto 606, Japan.
(Received
15 December
1982, accepted
Faculty
TAKEGAMI of Engineering,
10 August
Kyoto
University,
1983)
ABSTRACT Rapid synthesis of a zeolite which has catalytic activity for methanol conversion into C2%C4 olefins with high selectivity has been studied. Firstly, the crystallization of ZSM-34 class zeolite, using choline as the organic ingredient at 100°C for 131 days (standard method) has been followed by measurements of XRD, SEM, BET surface area and catalytic activity. An amorphous precursor of spherical shape was formed from the gel mixture within three days and intergrowth of zeolite crystals occurred in the spherical precursor. Optimum selectivity for olefin formation was obtained with a zeolite crystallized over 25 days. In order to reduce the crystallization time, we tried heating directly the gel at a constant rate of 2.8"C min-1 to 200°C and maintaining it at this temperature for 2 h (direct heating method). However, the catalyst life for methanol conversion was shortened. On the other hand, when the precursor was heated at a constant rate of 1.7"C min-i to 190°C and maintained at this temperature for 0.5 h (precursor heating method), the resulting zeolite exhibited a better performance than zeolites prepared by the standard and direct heating methods.
INTRODUCTION Shape selective extensively
zeolites
studied.
such as ZSM-5 [I,21 and ZSM-34
Particular
catalysts
because
synthesis
from methanol.
interest
of their excellent
has been paid to these new types of
selectivity
larly in ZSM-34 preparation
which
during
performance
catalytic
of the crystals
A reduction
performance
their preparation
and low efficiency
In this study, we have firstly investigated synthesis.
or lower olefin
procedures,
particu-
takes 25 to 196 days at 100°C. Long crystalliz-
ation times may give low reproducibility
zeolite
for gasoline
In general, however, these shape selective zeolites need
a very long time for crystallization
the catalytic
[3,4] have been
the change formed during
in crystallization
in zeolite
in physical
synthesis.
properties
and
the course of ZSM-34 class
time without
damage
to the
was achieved.
EXPERIMENTAL Standard
method
Preparation
of zeolite
Mobil Oil Co. However, 0166-9834/83/$03.00
preparation
of ZSM-34 class zeolite was based on the patent choline
literature
[5-71 was used instead of choline
0 1983 Elsevier Science Publishers B.V.
chloride
[4] of as the
188 organic
amine ingredient,
because
prepared with the use of choline from methanol
it has been confirmed
used were 30 wt% silica sol solution,
reagent grade sodium and potassium water.
sodium aluminate the choline container,
for olefin
synthesis
than zeolite which was prepared with the use of choline
The reaction materials
distilled
that zeolite which was
has a better performance
Appropriate
hydroxides,
amounts
solution,
50 wtX choline
of sodium hydroxide,
were added to the distilled the mixed aqueous
chloride.
sodium aluminate, solution
potassium
and
hydroxide
water and were dissolved.
solution
was kept at 0°C. In another
the silica sol solution was also made at 0°C. The two solutions
mixed quickly
and stirred vigorously
for 2 min using a Homo-Mixer
Kogyo Co.). The gel solution mixtures for various
were crystallized
at 54O'C for 3.5 h. The molar
in the results and discussion
with
under passage of air
(Na + K)/Al, K/(Na + K), choline/OH-
were fixed at 9.3, 7.3, 0.17 and 0.67, respectively. described
Kako
at 100°C in a thermostat
at lOO"C, then calcined
ratio of Si/Al,
were
(Tokushuki
periods from 0.25 to 131 days. The solid products were washed
water to pH = 9 and dried overnight
and
After adding
The improved method will be
section.
Characterization X-ray powder diffraction
patterns
(XRD) of the synthesized
using a Rigaku Denki Geigerflex-
with Ni-filtered
The size and shape of the samples were observed electron microscope
(SEM) MSM-102.
coated with a Au evaporated etrically method
measured
apparatus
Methanol
conversion
internal diameter.
was carried
was measured
pressure.
and 88 ~01% N2, was allowed
conversion
RESULTS Change
at the entrance
gas mixture,
products
About
reactor of 4.8 mm bed
of the catalyst
the catalyst was dried iri S~:ZL
flow. The reaction
The reaction
flow reactor.
tubular
heated and the catalyst
located
reaction,
to flow through
of 1000 h-l. The reaction
chromatograph
by the one point
TG-20.
out using a conventional
by a thermocouple
at 500°C for 0.5 h under a nitrogen
velocity
temperature
analyzer
was placed in a quartz
The reactor was electrically
bed. Prior to the methanol
under atmospheric
scanning
on brass pegs and
and procedure
150 mg (0.22 ml) of catalyst
temperature
CuKu radiation.
areas of the samples were gravim-
at liquid nitrogen
using a Shimadzu microthermogravimetric
Reaction
monochromatic
with a Hitachi-Akashi
The samples were mounted
film. BET surface
by N2 adsorption
samples were recorded
was carried composed
the catalyst were analyzed
out at 400°C
of 12 ~01% methanol
bed at a gas hourly space using a Yanagimoto
G 80 with a column of X-28.
AND DISCUSSION in properties
standard
preparation
The change
and catalytic
activity
with crystallization
time for the
method
in crystal
shape with crystallization
time at 100°C is shown in
gas
189
'IGURE 1
SEM micrographs
leriods by the standard
of the zeolites preparation
crystallites
method.
crystallized
for diff 'erent
190 Figure
1. The gel mixture
was converted
The shape and size of the spherical that the particles of XRD patterns
into spherical
particles
became larger and square.
for the zeolites
were maintained
crystallization
at 0.5 and 1 day show very poor crystallininty,
16 day sample were generated
XRD patterns catalysts
of ZSM-34
appeared.
hydrocarbons.
The catalytic
has the highest
activity
is expressed
particle
formation
increased
decreased.
products
selectivity
period corresponds
formation
yield
(DME) and C,%C5 by propylene
formed
[83. The
(STY) of DME and propylene. the BET surface
to the period of spherical
After 3 days, the BET surfcae
approached
increased
ether
and sharply, whereas
This period corresponds
sharply and then gradually
a highest
with decreasing
to the period of intergrowth
1/2dry
time
and different
are represented
among hydrocarbons
by the space-time
from the gel mixture.
this trend, propylene
shown by the 16
and BET surface areas of these
were dimethyl
In the first 3 days, DME was formed exclusively area of the catalyst
shown in the
[4]. When the crystallization
activities
In Figure 3, the hydrocarbon
since propylene catalytic
structures
of these XRD lines weakened
are shown in Figure 3. The products
intensities
time. The samples
but the sample at three days shows
to the main crystal
was very long (131 days), the intensity
3 days.
for 8 days, but after
in less than 3 days. The XRD pattern
day sample is like the XRD patterns
within
Figure 2 shows relative
of different
that the XRD lines which correspond
particles
level.
area
In concert with
DME formation.
of the zeolite crystal
This
in each
Bday
I
lbday
0
10
20
30
40
50
,
I
60
0
10
28
FIGURE 2
30
40
1
50
60
28
X-ray diffraction
periods by the standard
20
patterns
preparation
of the zeolites method.
crystallized
for different
191
Crystallization time (day)
FIGURE 3
Effects of crystallization
and specific
surface
spherical
particle.
paraffin
selectivity
the highest
gel mixture zeolite
After a very long crystallization increased
selectivity
occurs
selectivity
to olefin formation
particle
time suggests
with the zeolite
The most surprising
which
material,
surface
prepared
observation
of
and the change
is the precursor
in BET surface
crystallinity.
time, we firstly
of the
area. The crystallization
that the rate of crystallization
early stage but slows down with increasing
200°C as described
Consequently,
is that in the period of the first 3 days all the
and has very little internal
reduce the.crystallization
time, such as 131 days, decreased.
was obtained
1 month.
into the spherical
in each spherical
crystallization
and olefin
time of about
experiments
converted
crystal
activities
areas.
with a crystallization these sequential
time at 100°C on the catalytic
tried heating
area with is rapid in the
Therefore,
in order to
the gel directly
to
below.
Direct heating method The composition as described
of the solution
in the experimental
OH-. The molar
mixtures
section,
ratio of choline/OH-
was reduced
i.e. 0.26, because when the gel mixture was heated directly organic placed
ingredient
to 2OO"C,
the resulting
catalyst.
zeolite activity
as the standard
preparation
method
by the standard
crystals
contained
method
much
and life [S]. The gel was heating
for 2 h. The synthesized
Figure 4 shows the SEM photograph
was the same
ratio of choline/
to ea. l/3 of the standard method,
and was heated at a constant
to 200°C and then was maintained the same manner
for the molar
which was prepared
and gave poor catalytic
in an autoclave
for the gel preparation
except
rate of 2.8"C min
material
mentioned
and the relative
-1
was treated
above to provide intensities
in the
of the
192
0
I
I
I
I
I
IO
20
30
40
50
I 60
28 (b)
FIGURE 4
(a) SEM micrograph
crystallized
and (b) X-ray diffraction
by the direct heating method.
pattern of the zeolite
193 XRD pattern zeolite
for the zeolite.
prepared
crystals
formation activity zeolite
by the standard
were observed.
of the zeolite
prepared
reduction
Precursor
for methanol
suggesting
conversion
prepared
temperature
structure
by the standard
time would
or catalytic
preparation
occurred
The method
of gel preparation
except the molar
standard
preparation
formation,
without
was the same as described
a considerable
essential
change
in
The gel solution
formation.
to autoclaves
mixtures
The precursor
and the temperature
level for 0.5 h. For reference,
the precursor
were also treated
preparation
with different
method.
The change
crystallization
with the mothor
The crystallinity smaller
of the precursor
than that of the precursor
(Figure 2, 3 days),
probably
of the spherical
5a. The XRD patterns
liquor was
shape and XRD for these samples 5 and 6, respectively.
in the XRD patterns of the standard
(Figure 6a) was
preparation
of sodalite
precursor
was satisfactory,
(Figure 2, 5 days). crystals
conditions
of 160°C and
for the zeolites
crystals
are suggested
prepared
was carried
out on each catalyst
time yields
of products
crystals.
crystallized
When the crystallization
temperature
increased
was raised to 220°C.
marks,
are
the needle shaped
method.
reaction The space-
areas of these samples
For the zeolites
temoerature
into needle
conversion
preparation
7. BET surface
temper-
at 220°C. XRD patterns
The methanol
from the modified
to ca. l/IO and C2sC4 olefins
the crvstallization
transformed
increased
at 190 and 220°C. Therefore,
are shown in Figure
in this figure.
DME was the main product. DME decreased
were partially
from those of ZSM-34 with circular
to be sodalite
conditions
when the crystallization
and the number of these crystals
[9], distinguished
are superimposed
However,
However,
as can be seen from Figure
of the sample with crystallization
observed
method
due to the use of a smaller amount of choline.
ature was 19O"C, the spherical shaped crystals
at each
as the
0.5 h (Figure 6c) were the same as for the sample with crystallization of 100°C and 5 days
rate of
at 100°C for 29
in the same manner
are shown in Figures
reflected
at 100°C
was maintained
was crystallized
in crystal
conditions
is l/3 that of the
were maintained
was raised at a constant
days. The synthesized
materials
in the experimental
was 0.27, which
1.7"C min-' to 130, 160, 190 and 220°C and the temperature
formation
just
that if the
activity.
ratio of choline/OH-
method.
for 3 days for precursor transferred
somewhat
However,
It was thought
precursor
be expected
method.
early in the reaction,
heating method
section,
standard
C9]
1, the catalytic
was higher than that of the
method.
was raised after
square from that
that sodalite
As shown in Table
by carbon deposit
in crystallization
the zeolite
method,
for 25 days by the standard
as with the catalyst
shown in the
were not seen at all and uniform
by ZSM-34 formation.
of the catalyst
crystallization
which were typically
of the zeolite were also different
by the standard
of this zeolite crystallized
crystals
method
XRD patterns
was accompanied
deactivation
Spherical
at 130 and 16O"C, was raised to 19O"C,
dramatically. ethvlene
However. when
formation
decreased
method
astandard
31.8
39.0
21.6
28.2
C2=
'precursor heating method d total amounts of ali hydrocarbons
bdirect heating method
preparation
17.8
10.6
5.7
11.3
c1
100°C x 29 daysC
190°C x 0.5 hC
100°C x 3 days +
200°C x 2 hb
100°C x 25 daysa
conditions
35.8
25.2
35.2
43.0
C3=
0.4
3.8
4.5
1.5
C4
C4=
7.1
9.7
21.0
8.2
/mol%
prepared
1.35
2.02
1.27
1.18
began to decrease
5.4
4.0
6.5
4.7
c5<
/mol l-'
86.2
96.9
79.6
57.6
/%
MeOti conv.
methods.
ZHCd
by different
formed until MeOH conversion
1.7
7.7
5.5
3.1
C3
selectivity
of the zeolites
Hydrocarbon
and product distribution
Crystallization
Activities
TABLE 1
61.5
92.1
79.6
53.1
HC 1%
Conv. to
49.2
67.8
60.7
43.2
C2%C4,/%
Conv. to
24.7
4.8
0
4.5
DME /%
Conv. to
FIGURE 5
SEM micrographs
in the precursor
of the zeolites
heating method.
crystallized
(a) 100°C x 3 days,
under different
conditions
(b) 100°C x 3 days t 130°C x
0.5 h, (c) 100°C x 3 days + 160°C x 0.5 h, (d) 100°C x 3 days t 190°C x 0.5 h, (e) 100°C x 3 days + 220°C x 0.5 h.
196
(a)
k 10
0
20
(b)
30
40
50
60
28
FIGURE 6 conditions
X-ray diffraction in the precursor
patterns
of the zeolites
heating method.
crystallized
under different
(a) 100°C x 3 days,
(b) 100°C x 3 days
+ 130°C x 0.5 h, (c) 100°C x 3 days + 160°C x 0.5 h, (d) 100°C x 3 days + 190°C x 0.5 h, (e) 100°C x 3 days t 220°C x 0.5 h.
1.5
1.3
300 F
F ;
0.8
H
0.6
% 5
5
S .woM)c 5 :
0.4
k 0.2
0
1W 100
130
160
190
220
250
Jo
Crystallization temperature ("C)
FIGURE 7
Effects
on the catalytic 0,
C4H8; 0,
of crystallization activities
CH4; A,
temperature
and the specific
C3H8; n , C4H,0; 0,
in the precursor
surface
DME.
areas.
0,
heating method
C2H4; A
, C3H6;
197 markedly smaller
and DME increased.
than that of the 190°C sample.
the zeolite
crystallized
by the standard
mixture
attributed zeolite
catalyst
prepared
prepared
activity
was prepared
heating method,
by the standard
the olefin
time needed
reduced
by higher
to prepare temperature
heating method
(200DC,
selectivity method.
was lower than
The reason may be
On the other hand, with the heating method,
the
were higher than in the case of the and the direct
on the catalyst
1 h on stream was very small,
the crystallization significantly
method
crystallized
at 100°C for 29 days using the gel
preparation
selectivity
preparation
the carbon deposited
during
with the zeolites
at 190°C for 0.5 h in the precursor
and ethylene
by the standard
Moreover,
1 shows the product selectivity for
to the use of l/3 the amount of choline.
catalyst
catalytic
Table
(lOO°C, 25 days) and by the direct
catalyst
with the precursor
for the zeolite
area of the 220°C sample was markedly
at 190°C for 0.5 h compared
conditions
2 h). When the zeolite
method
The BET surface
prepared
indicating olefin
by the precursor long catalyst
selective
treatment
heating method. heating
life. Thus
zeolite could be
of the zeolite
precursor.
REFERENCES 1 2 3 4 5 6 7 8 9
S.L. Meisel, J.P. McCullough and C.H. Lechthaler, Chemtech, (1976) 86. Mobil Oil, U.S. Patent, 3,894,107 (1975). M.K. Rubin, E.J. Rosinski and C.J. Plank, U.S. Patent, 4,086,186 (1978). Mobil Oil Co., Jpn. Patent Application Disclosure, 58,499 (1978). T. Inui, E. Araki, T. Sezumi, T. Ishihara and Y. Takegami, React. Kinet. Catal., Lett, 18 (1981) 1. T. Inui, T. Ishihara and Y. Takegami, J.C.S. Chem. Comm., (1981) 936. T. Inui, T. Ishihara, N. Morinaga and Y. Takegami, React. Kinet. Catal. Lett., 19 (1982) 71. T. Inui, T. Ishihara, N. Morinaga, G. Takeuchi, E. Araki, T. Kanie and Y. Takegami, J. Chem. Sot. Japan., Chem. and Ind. Chem., (1982) 221. Ch. Baerlocher and W.M. Meier, Helv. Chim. Acta., 52 (1969) 1853.