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Toluene methylation over ici zeolite fu-1
63
Applied Catalysis, 9 (1984) 53-61 Elwier Science Publishers B.V., Amsterdam - Printed in The Netherlands
TOLUENE
METHYLATION
OVER ICI ZEOLITE FU-I
David G. PARKER Radiochemistry
Section,
Imperial
Chemical
Industries,
PLC, Billingham,
Cleveland,
TS23 ILB, U.K.
(Received
19 March
1983, accepted
3 November
1983)
ABSTRACT Toluene methylation over the ICI zeolite Fu-I is described. Using variously calcined and ion exchanged samples, it is demonstrated that the pore size constraint of Fu-I is such that the toluene methylation reaction occurs exclusively on the outer surface.
INTRODUCTION The last few years
has seen a dramatic
with high silica to alumina ZSM-5 which typically feature
ratios.
shows Si02/A1203
selectivities Recently including
synthesis
ICI have reported
the zeolite
toluene methylation
of approximately
of zeolites
that can be obtained the preparation
an important
6 i? which enables
This is highlighted
of p-dialkylbenzenes.
for paraxylene
in the synthesis
among these has been the Mobil zeolite
ratios of I5 - 100. However,
of ZSM-5 is a mean pore diameter
shape selective
increase
Notable
the
by the high
during toluene methylation
Cl].
of a number of high silica zeolites
Fu-I [2], and we now wish to report our observations
on
over this zeolite.
EXPERIMENTAL A sample of zeolite patent
literature
methods
to yield
Fu-I (Si02/A1203
[23 and subsequently
ratio 14.1) was prepared exchanged
and calcined
according
to the
by a variety
of
the acid form.
Calcination As prepared, hydroxide
by calcining examined.
Fu-I contains
(collectively
the zeolite.
Removal
tetramethylammonium
TMA). These
cations
large organic
In this work,
several
of TMA was readily monitored
and tetramethylammonium
molecules
calcination by infrared,
are generally procedures
removed
were
by measuring
the
diminution stretch
of the N-CH3 stretch at 1490 cm-' relative to the MO4 symmetrical -1 at 790 cm . Thus the smaller the ratio, 1490 cm-' :790 cm -1 , the greater
the destruction achieved.
of TMA. CHN analysis
The calcination
0166-9634/64/$03.00
methods
was employed
investigated
to assess
the degree of clean-up
and analytical
0 1984 Elaevier Science Publishers B.V.
results obtained
54 TABLE 1 Calcination
of Fu-I
Calcination
conditions
IR ratio
N-CH3
1469 cm-' 790 cm-'
%C
%N
%H
0.84
5.6
1.5
1.8
MO4 Prior to calcination In air, IO g sample As powder
CHN analysis
in a glass unit
24 h
200°C
0.83
5.6
1.6
24 h
350°C
0.56
3.5
1.0
12 h
450°C
0.30
3.6
0.5
0.18
1.6
0.5
0.8
0.94
2.6
0.6
0.9
Sample heated to 150°C under N2. Gas flow changed to NH3 1 ml s-1 and temperature raised to 450°C in 50"/15 min steps. Conditions maintained for 5 h and then cooled to room temp. under N2
0
0.8
0.5
0.7
The above NH3 calcined material was calcined in air at 400°C for 20 h
0
0.3
0.2
0.7
As 1 - 2.5 mm chips calcined
as above
Oven calcination 1 g sample, procedure typical for catalysts tested on microreactor for xylene isomerization, viz, 1 h 2OO"C, 1 h 3OO"C, 16 h 35O"C, 8 h 4OO"C, 16 h 450°C NH3 calcination,
IO g (chips) in glass unit
are listed in Table 1.
Cation exchange For Fu-1, the monovalent the remainder
TMA cation occupies
some of the zeolite
being filled with sodium ions. In order to convert
ally active acid form, and also to assess the efficiency exchanged prepared
samples of Fu-I, the following Fu-1 (sodium content
proton exchange with ammonium Fu-l(a) followed
and samples
Fu-l(b-d)
Direct proton exchange
Uncalcined
Fu-l(d) Ammonia/air Lanthanum
The various
of a number of different
were employed
to treat the
Fu-l(a) was prepared
were prepared
on uncalcined
by indirect
by direct
proton exchange
Fu-1 with
1.7 N hydrochloric
acid
(Na = 0.06%).
Fu-1 (followed
Fu-l(c) Air calcined
Fu-l(e)
1.01 wt%). Sample
sites,
ion as follows:
by air calcination
Fu-l(b)
methods
cation
to the catalytic-
by air calcination)
(Na = 0.07%).
Fu-I (Na = 0.05%). calcined
Fu-I (Na = 0.06%).
ion exchange
samplesof Fu-1
on air calcined
were pressed,
Fu-1 (Na = 0.16%, La = 2.6%).
crushed
and sieved to 1 - 2.5 mm mesh
FIGURE
1
Toluene methylation
and charged
to a gravity
to the first catalytic conditions
employed,
Feed toluene Catalyst Weight
fed tubular
reactor
unless otherwise (mole ratio)
(WHSV)
2.5 cm). Prior
stated, were:
1 f 0.1 h-'
temperature
450°C
were regenerated
Runs were generally
in air after each run for 15 h.
of 6 h duration
chromatography
and xylenes
were determined
toluene
conversion.
The analysis
(trimethylbenzenes,
etc.).
column
taken hourly and were analysed
at 90X).
as wt%, the measure
Routinely,
of catalyst
did not allow for the detection
Random analysis
a number of toluene methylation conversion
with samples
(Bentone/DIDP
toluene
% toluene
diameter
at 45O"C, and the reaction
6g
space velocity
by gas/liquid
(internal
2 : 1
charge
Catalysts
See text for key to sample treatments.
run, the zeolite was calcined
: methanol
hourly
Reaction
over Fu-l(a-e).
of various
benzene,
activity
being
of heavy ends
hourly samples
taken from
runs showed:
(+ heavy ends) = 1.25 x % toluene
conversionhithout
heavy
ends). Furthermore,
since the stoichiometry
and the reactants
should be 50%. If the toluene figure
for conversion
neglects
toluene
conversion
(with heavy ends) should
For convenience,
employed) catalytic
conversion
without
is 1:l toluene:methanol
the maximum
is related
lost via disproportionation
under the conditions
as toluene
of the reaction
fed are 2:l toluene:methanol,
conversion
be approximately
which
of toluene
to moles of methanol
is, however,
feed the
doubled. (This small for Fu-1
C31. activity
of the various
heavy ends.
samples of Fu-1 is recorded
TABLE 2 Product distributions Catalyst
Time on
code
stream/h
Fu-l(a)
Benzene
ZXylenes
Xp
%m
%o
89.5
10.3
23.0
50.6
26.3
4
92.0
8.0
24.4
42.1
33.4
6
92.3
7.7
28.5
28.5
42.9
2
Fu-l(b)
0.21
89.6
9.7
23.1
53.6
23.2
4
91.7
8.3
22.7
50.5
26.7
6
90.5
9.51
24.4
41.9
33.6
2
Fu-l(c)
Fu-l(d)
Fu-l(e)
Toluene
0.65
2
0.16
89.8
10.0
24.6
43.8
31.6
4
0.09
88.0
11.9
27.9
34.5
37.5
6
0.04
87.0
12.9
30.2
28.2
41.5
2
0.11
91.7
8.2
26.0
37.7
36.3
4
0.05
88.4
11.6
29.7
27.3
42.9
6
0.02
88.6
11.4
30.1
25.5
44.3
91.3
8.7
25.5
33.1
41.4 46.4 48.3
2 4
90.9
9.0
28.3
25.3
6
92.0
7.9
28.6
23.1
RESULTS AND DISCUSSION Results of catalytic
runs on the variously
Fu-1 are shown in Figure H-form, ammonium catalyst
1. It is readily
ion exchange
followed
for toluene methylation
Furthermore,
ammonium
calcined/ion
by thermal
followed
by thermal
more beneficial
if the zeolite
also be noticed
that for (c) and (d) the activity
is precalcined
increase and this will be discussed zeolite
Fu-l(e)
zeolite
(cf reference
Of central fraction
interest
product.
to approximately
From the data presented that ammonia
zeolite.
However,
of the catalyst
isomers
to be It will
ion exchanged
ion exchanged
than HY). of the xylene
with the C6-C8 product distrib-
for C8 distribution
show that during the
tend from the thermodynamic
equilibrium
30:25:45.
here on calcination,
treatment
appears
shows an initial
than the calcined/ammonium
This, together
course of a six hour run the xylene
apparent
degradation
(air or atmnonia), Fu-l(c,d).
REY is more active
utions, are set out in Table 2. Figures
of p:m:o 25:50:25
gives a more active
with HCl (Fu-l(a)).
to this study was the isomer distribution
in the reaction
samples of of the
later in the text. The lanthanum
shows a lower activity [4] where
degradation
than direct exchange
ion exchange
exchanged
seen that for preparation
and in other studies
[4,53, it is
is by far the best method for producing
the sample of Fu-1 calcined
under ammonia,
after
a clean
ion exchange
57
I
0
FIGURE 2
Variation
in W.H.S.V.
FIGURE 3
Variation
in temperature
F&l(d)
(h-l) for catalyst
It was subsequently
Fu-l(c).
("C) for catalyst
was found to be no more active
Fu-l(c).
4
umlkn
Fu-l(c).
than the air calcined/ion
discovered
that Fu-1 zeolites
exchanged
For several different
samples of Fu-1 it was found that after a catalytic
(toluene methylation)
and regeneration,
significantly
diminished
From the catalytic evident
difference
between
is perhaps ammonium xylene
surprising
TMA band at 1490 cm-' was
exchanged
samples of Fu-1 it is
gives the most active catalyst
and, with time on line, it appears
calcined/exchanged
ion exchange
isomerisation
of the different
ion exchange/degradation
for toluene methylation
run
or lost altogether.
testing
that ammonium
the infrared
sample
clean up 'on line'.
that HCl exchange since it appears catalyst
that there is little
Fu-l(c) or exchanged/calcined gave a catalyst that the former
C63. Acid treatment
Fu-l(b).
of poorer activity procedure
It
than
gives a better
may, in some cases,
induce
I
Q
20
0
slrlnrhln
FIGURE 4
Toluene methylation
dealumination
of zeolites
this study are unlikely In an attempt selected
[7]. However,
increase
distribution rapidly
conversion
Again, however,
was observed,
and catalyst
is shown in Figure 2 and catalyst
in WHSV decreases
the pattern of xylenes
a typical
catalytic which
acid catalysed A similar
is essentially
toluene methylation
result was obtained
selectivity
in Figure 3.
is given in Table 3. As expected,
increase
to 0% m-xylene,
involves
with the low activity
from the thermodynamic more from
a 40:60 p:o xylene
product distribution
silica/alumina
reaction
ratio
of Fu-1
cracking
at the surface
of Fu-1 compared
in the pores [I] suggests
to p-xylene
of the
to zeolites
that for Fu-1 reaction
in toluene methylation
has been treated with compounds
Presumably,
these compounds
where is
of the elements
has been reported
surface,
This then leaves only the sterically
for
of Group VIA [l].
are too large to enter the zeolitic
and react only with acid sites on the outer zeolitic activity.
increases
to para-xylene
at the surface of the zeolite.
ZSM-5 which
catalytic
in temperature
selectivity
p:m:o product mix. This occurred
using an amorphous
this together
Increased
The effect of
bed temperature
[9], (Figure 4).
catalyst,
is known to occur
in operating
bed temperature.
enhanced
the kinetic
Since the latter obviously
taking place exclusively
of variation
Indeed, when the isomer distribution
run was extrapolated
we
exchanged/calcined
being as before with a tendency
catalyst.
reaction
whilst
towards a 30:25:45
at the higher space velocity.
was obtained,
products
no significant
in
of the Fu-1 zeolite
from the variously
of the aromatic
employed
in Fu-1 [S].
and studied the effects
such as space velocity
The isomer distribution
conversion.
catalyst
to 0% meta-xylene.
the rather mild conditions
to assess the pore size characteristics
samples of Fu-1, i.e. Fu-l(c),
space velocity
extrapolation
to cause dealumination
the best performance
conditions,
over Fu-l(c);
pores of ZSM-5
poisoning
constrained
their
internal
acid
TABLE 3 Effect of variation
in WHSV and catalyst
Catalyst
WHSV
Reaction
Time on
run no.
h-'
temp./"C
stream/h
55
0.9
450
1.9
53
450
3.3
54
450
0.9
67
400
0.9
63
500
bed temperature
Benzene /wt%
for Fu-l(c).
Toluene
cxylenes
/wt%
/wt%
%p
%m
%o
2
0.02
88.6
11.2
25.0
42.9
32.1
4
0.01
87.7
12.2
28.1
33.6
38.4
6
-
86.9
13.1
30.5
26.9
42.7
2
0.02
91.6
8.4
28.5
26.9
44.6
4
-
91.0
9.1
29.5
24.3
46.2
6
-
91.0
9.4
29.4
24.4
46.3
2
-
91.8
8.2
29.1
24.6
46.4
24.7
46.0
4
-
91.5
8.5
29.3
6
-
91.7
8.3
29.5
24.7
45.8
2
0.1
91.1
8.8
30.0
27.7
42.3
4
-
89.4
10.6
31.4
26.0
42.7
6
-
89.9
10.1
30.6
24.4
45.0
2
0.4
86.5
13.1
25.2
44.1
30.7
4
0.2
85.4
14.5
28.7
33.4
37.9
6
0.1
85.5
14.4
30.6
28.3
41.1
TABLE 4 Xylene
isomer distribution. xXylenes/wt%
Time on stream
Distribution %P
%m
%o
24.6
43.8
31.6
Untreated 10.0
2 4
11.9
27.9
34.5
37.6
6
12.9
30.2
28.2
41.6
4.5
23.9
29.1
47.0
9.1
24.9
24.3
50.8
6.7
24.3
25.2
50.6
Treated with
(Me013
sites available observed.
for reaction
Further
outer surface
evidence
and consequently
that toluene
methylation
of Fu-1 came from the observation
with trimethylphosphite,
gives rise to the selectivity was occurring
only on the
that when this material
not only was the catalytic
activity
decreased,
was treated but the
60 distribution
of product
Final confirmation
xylenes favoured,
of the inaccessibility
toluene came from the following was air calcined sites within leaving
the zeolitic
revealed
ether was detected,
Support
that virtually arising
reaction
conditions.
GLC analysis
However,
to toluene,
of the way a variety
on the outer surface
to molecules toluene
with a diameter
of
condensation.
This
other
the toluene
of the zeolite. reactant
ICI studies
molecules [IO].
interact with the hydroxyl
to the internal
acid sites was limited
of <5.5 8. This is too small for molecules
on the initial increase
of Fu-1 (see figure for Fu-l(c)).
toluene methylation experimental toluene
of the product
such as
and xylenes.
It is also worth commenting samples
of molecules
that access
while
acid sites of Fu-1, while
thus forcing
to the internal acid sites of Fu-1 comes from various From observations
acid
NMR/IR analysis
of limited access for the bigger
groups of Fu-1 it was concluded
i.e. Na-form
produce
had been lost, while dimethyl
that the internal
to occur exclusively
of Fu-1 to
(2:l) were then fed
from simple acid catalysed
are inaccessible
for the observation
surface
(Table 4).
ion degradation,
and methanol
all the methanol
with the argument
to methanol,
methylation
Toluene
operating
isomer
that this would
pores from tetramethylammonium
probably
is consistent
accessible
of the internal
that no xylenes were being formed.
indicated
the ortho
Fu-1 in its "as prepared",
It was postulated
the surface devoid of acidity.
this stream
result
experiment.
in a glass unit.
over this sample under standard stream
if anything,
over zeolite-Y
evidence
methylation.
However,
to give linear hydrocarbons
methanol
in activity
observed
the pores,
more available
observed
has been reported
no explanation
study points
to surface
with toluene
for The
alone for
pores and reacts
for this reaction
rapidly
may be due to less methanol
for reaction
for
was advanced.
reaction
will enter Fu-1 zeolite
[II]. The activity
Thus, the increase leaving
Such an effect
[3] although
in the present
in activity
decays.
reacting
in
at the surface.
CONCLUSION The evidence
presented
not have properties toluene,
in this study clearly
suitable
for inducing
the pore size constraint
methylation
reaction
therefore
indicates
shape selective
being rather
that zeolite alkylation
Fu-1 does
reactions
less than 6 A. The toluene
occurs exclusively
at the zeolite
surface.
ACKNOWLEDGEMENTS The author their helpful
wishes
to thank Drs. R.J. Sampson,
J. Dewing and A. Stewart
comments.
REFERENCES 1
U.S. Patents
3,965,207 3,965,208 3,865,209 3,965,210
B. Weinstein S.A. Butter and W.W. Kaeding S.A. Butter and L.B. Young C.C. Chu
for
of
61 4,007,231 S.A. Butter 4,001,346 C.C. Chu 4,002,697 N.Y. Chen 4,002,698 W.W. Kaeding (all to Mobil Oil). 2 German patent application 1978, 2,748,278. U.S. Patent 4,209,498 also provisional U.S. Patent 4,300,013 (all to T.V. Whittam, ICI); D.G. Parker and D. Seddon, unpublished results. T. Yashima, H. Ahmad, K. Yamazaki, M. Katsuta and N. Hara, J. Catal., 16 (1970 273: 17 (1970) 151. T. Yashima, K. Sato, T. Hayasaka and N. Hara, J. Catal., 26 (1972) 303. 5 M.A. Day, D.G. Parker and A. Stewart, unpublished results. 6 D. Seddon and T.V. Whittam, personal communication. 7 W.L. Kranich, Y.H. Ma, L.B. Sand, A.H. Weiss and I. Zwiebel, "Molecular S'ieve Zeolites (I)", Advan. Chem. Ser., (1971) 101. M.S. Spencer, personal communication. 8 D. Seddon, Applied Catalysis, 7 (1983) 327. R.H. Allen and L.D. Yates, J.A.C.S., 83 (1961) 2799. 80 J. Dewing, F. Pierce and A. Stewart, JCS Chem. Commun., (1980) 718. J. Dewing, F. Pierce and A. Stewart in "Catalysis by Zeolites", 8. Imelik et al., Eds., Studies in Surface Science and Catalysis No. 5, Elsevier, Amsterdam, (1980), p. 39. 11 M.S. Spencer and T.V. Whittam, J. Mol. Catalysis, in press.
Applied Catalysis, 9 (1984) 53-61 Elwier Science Publishers B.V., Amsterdam - Printed in The Netherlands
TOLUENE
METHYLATION
OVER ICI ZEOLITE FU-I
David G. PARKER Radiochemistry
Section,
Imperial
Chemical
Industries,
PLC, Billingham,
Cleveland,
TS23 ILB, U.K.
(Received
19 March
1983, accepted
3 November
1983)
ABSTRACT Toluene methylation over the ICI zeolite Fu-I is described. Using variously calcined and ion exchanged samples, it is demonstrated that the pore size constraint of Fu-I is such that the toluene methylation reaction occurs exclusively on the outer surface.
INTRODUCTION The last few years
has seen a dramatic
with high silica to alumina ZSM-5 which typically feature
ratios.
shows Si02/A1203
selectivities Recently including
synthesis
ICI have reported
the zeolite
toluene methylation
of approximately
of zeolites
that can be obtained the preparation
an important
6 i? which enables
This is highlighted
of p-dialkylbenzenes.
for paraxylene
in the synthesis
among these has been the Mobil zeolite
ratios of I5 - 100. However,
of ZSM-5 is a mean pore diameter
shape selective
increase
Notable
the
by the high
during toluene methylation
Cl].
of a number of high silica zeolites
Fu-I [2], and we now wish to report our observations
on
over this zeolite.
EXPERIMENTAL A sample of zeolite patent
literature
methods
to yield
Fu-I (Si02/A1203
[23 and subsequently
ratio 14.1) was prepared exchanged
and calcined
according
to the
by a variety
of
the acid form.
Calcination As prepared, hydroxide
by calcining examined.
Fu-I contains
(collectively
the zeolite.
Removal
tetramethylammonium
TMA). These
cations
large organic
In this work,
several
of TMA was readily monitored
and tetramethylammonium
molecules
calcination by infrared,
are generally procedures
removed
were
by measuring
the
diminution stretch
of the N-CH3 stretch at 1490 cm-' relative to the MO4 symmetrical -1 at 790 cm . Thus the smaller the ratio, 1490 cm-' :790 cm -1 , the greater
the destruction achieved.
of TMA. CHN analysis
The calcination
0166-9634/64/$03.00
methods
was employed
investigated
to assess
the degree of clean-up
and analytical
0 1984 Elaevier Science Publishers B.V.
results obtained
54 TABLE 1 Calcination
of Fu-I
Calcination
conditions
IR ratio
N-CH3
1469 cm-' 790 cm-'
%C
%N
%H
0.84
5.6
1.5
1.8
MO4 Prior to calcination In air, IO g sample As powder
CHN analysis
in a glass unit
24 h
200°C
0.83
5.6
1.6
24 h
350°C
0.56
3.5
1.0
12 h
450°C
0.30
3.6
0.5
0.18
1.6
0.5
0.8
0.94
2.6
0.6
0.9
Sample heated to 150°C under N2. Gas flow changed to NH3 1 ml s-1 and temperature raised to 450°C in 50"/15 min steps. Conditions maintained for 5 h and then cooled to room temp. under N2
0
0.8
0.5
0.7
The above NH3 calcined material was calcined in air at 400°C for 20 h
0
0.3
0.2
0.7
As 1 - 2.5 mm chips calcined
as above
Oven calcination 1 g sample, procedure typical for catalysts tested on microreactor for xylene isomerization, viz, 1 h 2OO"C, 1 h 3OO"C, 16 h 35O"C, 8 h 4OO"C, 16 h 450°C NH3 calcination,
IO g (chips) in glass unit
are listed in Table 1.
Cation exchange For Fu-1, the monovalent the remainder
TMA cation occupies
some of the zeolite
being filled with sodium ions. In order to convert
ally active acid form, and also to assess the efficiency exchanged prepared
samples of Fu-I, the following Fu-1 (sodium content
proton exchange with ammonium Fu-l(a) followed
and samples
Fu-l(b-d)
Direct proton exchange
Uncalcined
Fu-l(d) Ammonia/air Lanthanum
The various
of a number of different
were employed
to treat the
Fu-l(a) was prepared
were prepared
on uncalcined
by indirect
by direct
proton exchange
Fu-1 with
1.7 N hydrochloric
acid
(Na = 0.06%).
Fu-1 (followed
Fu-l(c) Air calcined
Fu-l(e)
1.01 wt%). Sample
sites,
ion as follows:
by air calcination
Fu-l(b)
methods
cation
to the catalytic-
by air calcination)
(Na = 0.07%).
Fu-I (Na = 0.05%). calcined
Fu-I (Na = 0.06%).
ion exchange
samplesof Fu-1
on air calcined
were pressed,
Fu-1 (Na = 0.16%, La = 2.6%).
crushed
and sieved to 1 - 2.5 mm mesh
FIGURE
1
Toluene methylation
and charged
to a gravity
to the first catalytic conditions
employed,
Feed toluene Catalyst Weight
fed tubular
reactor
unless otherwise (mole ratio)
(WHSV)
2.5 cm). Prior
stated, were:
1 f 0.1 h-'
temperature
450°C
were regenerated
Runs were generally
in air after each run for 15 h.
of 6 h duration
chromatography
and xylenes
were determined
toluene
conversion.
The analysis
(trimethylbenzenes,
etc.).
column
taken hourly and were analysed
at 90X).
as wt%, the measure
Routinely,
of catalyst
did not allow for the detection
Random analysis
a number of toluene methylation conversion
with samples
(Bentone/DIDP
toluene
% toluene
diameter
at 45O"C, and the reaction
6g
space velocity
by gas/liquid
(internal
2 : 1
charge
Catalysts
See text for key to sample treatments.
run, the zeolite was calcined
: methanol
hourly
Reaction
over Fu-l(a-e).
of various
benzene,
activity
being
of heavy ends
hourly samples
taken from
runs showed:
(+ heavy ends) = 1.25 x % toluene
conversionhithout
heavy
ends). Furthermore,
since the stoichiometry
and the reactants
should be 50%. If the toluene figure
for conversion
neglects
toluene
conversion
(with heavy ends) should
For convenience,
employed) catalytic
conversion
without
is 1:l toluene:methanol
the maximum
is related
lost via disproportionation
under the conditions
as toluene
of the reaction
fed are 2:l toluene:methanol,
conversion
be approximately
which
of toluene
to moles of methanol
is, however,
feed the
doubled. (This small for Fu-1
C31. activity
of the various
heavy ends.
samples of Fu-1 is recorded
TABLE 2 Product distributions Catalyst
Time on
code
stream/h
Fu-l(a)
Benzene
ZXylenes
Xp
%m
%o
89.5
10.3
23.0
50.6
26.3
4
92.0
8.0
24.4
42.1
33.4
6
92.3
7.7
28.5
28.5
42.9
2
Fu-l(b)
0.21
89.6
9.7
23.1
53.6
23.2
4
91.7
8.3
22.7
50.5
26.7
6
90.5
9.51
24.4
41.9
33.6
2
Fu-l(c)
Fu-l(d)
Fu-l(e)
Toluene
0.65
2
0.16
89.8
10.0
24.6
43.8
31.6
4
0.09
88.0
11.9
27.9
34.5
37.5
6
0.04
87.0
12.9
30.2
28.2
41.5
2
0.11
91.7
8.2
26.0
37.7
36.3
4
0.05
88.4
11.6
29.7
27.3
42.9
6
0.02
88.6
11.4
30.1
25.5
44.3
91.3
8.7
25.5
33.1
41.4 46.4 48.3
2 4
90.9
9.0
28.3
25.3
6
92.0
7.9
28.6
23.1
RESULTS AND DISCUSSION Results of catalytic
runs on the variously
Fu-1 are shown in Figure H-form, ammonium catalyst
1. It is readily
ion exchange
followed
for toluene methylation
Furthermore,
ammonium
calcined/ion
by thermal
followed
by thermal
more beneficial
if the zeolite
also be noticed
that for (c) and (d) the activity
is precalcined
increase and this will be discussed zeolite
Fu-l(e)
zeolite
(cf reference
Of central fraction
interest
product.
to approximately
From the data presented that ammonia
zeolite.
However,
of the catalyst
isomers
to be It will
ion exchanged
ion exchanged
than HY). of the xylene
with the C6-C8 product distrib-
for C8 distribution
show that during the
tend from the thermodynamic
equilibrium
30:25:45.
here on calcination,
treatment
appears
shows an initial
than the calcined/ammonium
This, together
course of a six hour run the xylene
apparent
degradation
(air or atmnonia), Fu-l(c,d).
REY is more active
utions, are set out in Table 2. Figures
of p:m:o 25:50:25
gives a more active
with HCl (Fu-l(a)).
to this study was the isomer distribution
in the reaction
samples of of the
later in the text. The lanthanum
shows a lower activity [4] where
degradation
than direct exchange
ion exchange
exchanged
seen that for preparation
and in other studies
[4,53, it is
is by far the best method for producing
the sample of Fu-1 calcined
under ammonia,
after
a clean
ion exchange
57
I
0
FIGURE 2
Variation
in W.H.S.V.
FIGURE 3
Variation
in temperature
F&l(d)
(h-l) for catalyst
It was subsequently
Fu-l(c).
("C) for catalyst
was found to be no more active
Fu-l(c).
4
umlkn
Fu-l(c).
than the air calcined/ion
discovered
that Fu-1 zeolites
exchanged
For several different
samples of Fu-1 it was found that after a catalytic
(toluene methylation)
and regeneration,
significantly
diminished
From the catalytic evident
difference
between
is perhaps ammonium xylene
surprising
TMA band at 1490 cm-' was
exchanged
samples of Fu-1 it is
gives the most active catalyst
and, with time on line, it appears
calcined/exchanged
ion exchange
isomerisation
of the different
ion exchange/degradation
for toluene methylation
run
or lost altogether.
testing
that ammonium
the infrared
sample
clean up 'on line'.
that HCl exchange since it appears catalyst
that there is little
Fu-l(c) or exchanged/calcined gave a catalyst that the former
C63. Acid treatment
Fu-l(b).
of poorer activity procedure
It
than
gives a better
may, in some cases,
induce
I
Q
20
0
slrlnrhln
FIGURE 4
Toluene methylation
dealumination
of zeolites
this study are unlikely In an attempt selected
[7]. However,
increase
distribution rapidly
conversion
Again, however,
was observed,
and catalyst
is shown in Figure 2 and catalyst
in WHSV decreases
the pattern of xylenes
a typical
catalytic which
acid catalysed A similar
is essentially
toluene methylation
result was obtained
selectivity
in Figure 3.
is given in Table 3. As expected,
increase
to 0% m-xylene,
involves
with the low activity
from the thermodynamic more from
a 40:60 p:o xylene
product distribution
silica/alumina
reaction
ratio
of Fu-1
cracking
at the surface
of Fu-1 compared
in the pores [I] suggests
to p-xylene
of the
to zeolites
that for Fu-1 reaction
in toluene methylation
has been treated with compounds
Presumably,
these compounds
where is
of the elements
has been reported
surface,
This then leaves only the sterically
for
of Group VIA [l].
are too large to enter the zeolitic
and react only with acid sites on the outer zeolitic activity.
increases
to para-xylene
at the surface of the zeolite.
ZSM-5 which
catalytic
in temperature
selectivity
p:m:o product mix. This occurred
using an amorphous
this together
Increased
The effect of
bed temperature
[9], (Figure 4).
catalyst,
is known to occur
in operating
bed temperature.
enhanced
the kinetic
Since the latter obviously
taking place exclusively
of variation
Indeed, when the isomer distribution
run was extrapolated
we
exchanged/calcined
being as before with a tendency
catalyst.
reaction
whilst
towards a 30:25:45
at the higher space velocity.
was obtained,
products
no significant
in
of the Fu-1 zeolite
from the variously
of the aromatic
employed
in Fu-1 [S].
and studied the effects
such as space velocity
The isomer distribution
conversion.
catalyst
to 0% meta-xylene.
the rather mild conditions
to assess the pore size characteristics
samples of Fu-1, i.e. Fu-l(c),
space velocity
extrapolation
to cause dealumination
the best performance
conditions,
over Fu-l(c);
pores of ZSM-5
poisoning
constrained
their
internal
acid
TABLE 3 Effect of variation
in WHSV and catalyst
Catalyst
WHSV
Reaction
Time on
run no.
h-'
temp./"C
stream/h
55
0.9
450
1.9
53
450
3.3
54
450
0.9
67
400
0.9
63
500
bed temperature
Benzene /wt%
for Fu-l(c).
Toluene
cxylenes
/wt%
/wt%
%p
%m
%o
2
0.02
88.6
11.2
25.0
42.9
32.1
4
0.01
87.7
12.2
28.1
33.6
38.4
6
-
86.9
13.1
30.5
26.9
42.7
2
0.02
91.6
8.4
28.5
26.9
44.6
4
-
91.0
9.1
29.5
24.3
46.2
6
-
91.0
9.4
29.4
24.4
46.3
2
-
91.8
8.2
29.1
24.6
46.4
24.7
46.0
4
-
91.5
8.5
29.3
6
-
91.7
8.3
29.5
24.7
45.8
2
0.1
91.1
8.8
30.0
27.7
42.3
4
-
89.4
10.6
31.4
26.0
42.7
6
-
89.9
10.1
30.6
24.4
45.0
2
0.4
86.5
13.1
25.2
44.1
30.7
4
0.2
85.4
14.5
28.7
33.4
37.9
6
0.1
85.5
14.4
30.6
28.3
41.1
TABLE 4 Xylene
isomer distribution. xXylenes/wt%
Time on stream
Distribution %P
%m
%o
24.6
43.8
31.6
Untreated 10.0
2 4
11.9
27.9
34.5
37.6
6
12.9
30.2
28.2
41.6
4.5
23.9
29.1
47.0
9.1
24.9
24.3
50.8
6.7
24.3
25.2
50.6
Treated with
(Me013
sites available observed.
for reaction
Further
outer surface
evidence
and consequently
that toluene
methylation
of Fu-1 came from the observation
with trimethylphosphite,
gives rise to the selectivity was occurring
only on the
that when this material
not only was the catalytic
activity
decreased,
was treated but the
60 distribution
of product
Final confirmation
xylenes favoured,
of the inaccessibility
toluene came from the following was air calcined sites within leaving
the zeolitic
revealed
ether was detected,
Support
that virtually arising
reaction
conditions.
GLC analysis
However,
to toluene,
of the way a variety
on the outer surface
to molecules toluene
with a diameter
of
condensation.
This
other
the toluene
of the zeolite. reactant
ICI studies
molecules [IO].
interact with the hydroxyl
to the internal
acid sites was limited
of <5.5 8. This is too small for molecules
on the initial increase
of Fu-1 (see figure for Fu-l(c)).
toluene methylation experimental toluene
of the product
such as
and xylenes.
It is also worth commenting samples
of molecules
that access
while
acid sites of Fu-1, while
thus forcing
to the internal acid sites of Fu-1 comes from various From observations
acid
NMR/IR analysis
of limited access for the bigger
groups of Fu-1 it was concluded
i.e. Na-form
produce
had been lost, while dimethyl
that the internal
to occur exclusively
of Fu-1 to
(2:l) were then fed
from simple acid catalysed
are inaccessible
for the observation
surface
(Table 4).
ion degradation,
and methanol
all the methanol
with the argument
to methanol,
methylation
Toluene
operating
isomer
that this would
pores from tetramethylammonium
probably
is consistent
accessible
of the internal
that no xylenes were being formed.
indicated
the ortho
Fu-1 in its "as prepared",
It was postulated
the surface devoid of acidity.
this stream
result
experiment.
in a glass unit.
over this sample under standard stream
if anything,
over zeolite-Y
evidence
methylation.
However,
to give linear hydrocarbons
methanol
in activity
observed
the pores,
more available
observed
has been reported
no explanation
study points
to surface
with toluene
for The
alone for
pores and reacts
for this reaction
rapidly
may be due to less methanol
for reaction
for
was advanced.
reaction
will enter Fu-1 zeolite
[II]. The activity
Thus, the increase leaving
Such an effect
[3] although
in the present
in activity
decays.
reacting
in
at the surface.
CONCLUSION The evidence
presented
not have properties toluene,
in this study clearly
suitable
for inducing
the pore size constraint
methylation
reaction
therefore
indicates
shape selective
being rather
that zeolite alkylation
Fu-1 does
reactions
less than 6 A. The toluene
occurs exclusively
at the zeolite
surface.
ACKNOWLEDGEMENTS The author their helpful
wishes
to thank Drs. R.J. Sampson,
J. Dewing and A. Stewart
comments.
REFERENCES 1
U.S. Patents
3,965,207 3,965,208 3,865,209 3,965,210
B. Weinstein S.A. Butter and W.W. Kaeding S.A. Butter and L.B. Young C.C. Chu
for
of
61 4,007,231 S.A. Butter 4,001,346 C.C. Chu 4,002,697 N.Y. Chen 4,002,698 W.W. Kaeding (all to Mobil Oil). 2 German patent application 1978, 2,748,278. U.S. Patent 4,209,498 also provisional U.S. Patent 4,300,013 (all to T.V. Whittam, ICI); D.G. Parker and D. Seddon, unpublished results. T. Yashima, H. Ahmad, K. Yamazaki, M. Katsuta and N. Hara, J. Catal., 16 (1970 273: 17 (1970) 151. T. Yashima, K. Sato, T. Hayasaka and N. Hara, J. Catal., 26 (1972) 303. 5 M.A. Day, D.G. Parker and A. Stewart, unpublished results. 6 D. Seddon and T.V. Whittam, personal communication. 7 W.L. Kranich, Y.H. Ma, L.B. Sand, A.H. Weiss and I. Zwiebel, "Molecular S'ieve Zeolites (I)", Advan. Chem. Ser., (1971) 101. M.S. Spencer, personal communication. 8 D. Seddon, Applied Catalysis, 7 (1983) 327. R.H. Allen and L.D. Yates, J.A.C.S., 83 (1961) 2799. 80 J. Dewing, F. Pierce and A. Stewart, JCS Chem. Commun., (1980) 718. J. Dewing, F. Pierce and A. Stewart in "Catalysis by Zeolites", 8. Imelik et al., Eds., Studies in Surface Science and Catalysis No. 5, Elsevier, Amsterdam, (1980), p. 39. 11 M.S. Spencer and T.V. Whittam, J. Mol. Catalysis, in press.