| Dokumentenidentifikation |
EP1485322 27.12.2007 |
| EP-Veröffentlichungsnummer |
0001485322 |
| Titel |
VERFAHREN ZUR HERSTELLUNG EINES ZSM-5 KATALYSATORS |
| Anmelder |
Council of Scientific & Industrial Research, New Delhi, IN |
| Erfinder |
KULKARNI, Shivanand Janardan, Hyderabad 500 007 Andhra Pradesch, IN;
NAMA, Narendar, Hyderabad 500 007 Andhra Pradesch, IN;
PAVULURI, Srinivasu, Hyderabad 500 007 Andhra Pradesch, IN;
RAGHAVAN, Kondapuram Vijaja, Hyderabad 500 007 Andhra Pradesch, IN |
| Vertreter |
derzeit kein Vertreter bestellt |
| DE-Aktenzeichen |
60223595 |
| Vertragsstaaten |
AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LI, LU, MC, NL, PT, SE, TR |
| Sprache des Dokument |
EN |
| EP-Anmeldetag |
21.03.2002 |
| EP-Aktenzeichen |
027131663 |
| WO-Anmeldetag |
21.03.2002 |
| PCT-Aktenzeichen |
PCT/IN02/00055 |
| WO-Veröffentlichungsnummer |
2003080510 |
| WO-Veröffentlichungsdatum |
02.10.2003 |
| EP-Offenlegungsdatum |
15.12.2004 |
| EP date of grant |
14.11.2007 |
| Veröffentlichungstag im Patentblatt |
27.12.2007 |
| IPC-Hauptklasse |
C01B 39/38(2006.01)A, F, I, 20051017, B, H, EP
|
| IPC-Nebenklasse |
C01B 39/40(2006.01)A, L, I, 20051017, B, H, EP
|
| Beschreibung[en] |
|
Field of the invention
The present invention relates to an improved process for
the preparation of crystalline ZSM-5 pentasil type of zeolite like ZSM-5 (Zeolite
Socony Mobil-5), which are useful in acid catalyzed reactions.
Background of the invention
The synthesis of ZSM-5 is reported in
US Patent 3702886 (1972
). In the presently known processes ZSM-5 was synthesized from a mixture
of alkali metal cation, especially sodium, tetra alkyl ammonium cation, aluminum
source like sodium aluminate, silica source like sodium silicate and water in the
pH range of 6.7 to 13.0, the autoclavation temperature of 120°- 200°C
under autogeneous pressure. The ZSM-5 material showed characteristic X-ray diffraction
pattern The ZSM-5 catalyst was initially prepared within eight days, typically at
150°C for six days. There are various attempts to reduce the time of the autoclavation
from six days to two days by seeding gel method (
Microporous Materials 22, 626-627 (1998)
. The attempts have been made to reduce the autoclavation time by using
anionic promoters like H3PO4 (Nature, 381,298 (1996)) and by varying
ratios of various precursors (Zeolites 12, 943 (1992)). Many other patents have
been reported in the literature. These methods have some limitations and cannot
be commercialized. The limitations are (1) X-ray crystalline purity, (2) crystalline
phase purity (3) the promoter cation enters into tetrahedral position like the arsenate
promoter leads to arsanate-silicalite with different catalytic properties. (4) The
definite Si/A1 ratio in the gel and the product (5) product yield.
Objects of the invention
Accordingly it is an object of the invention to provide
a process for the preparation of ZSM-5 catalyst which is commercially feasible.
It is another object of the invention, to provide a process
for the preparation of ZSM-5 catalyst which shows high X-ray and crystalline phase
purity and specific Si/Al ratios.
It is a further object of the invention to provide a process
for the preparation of ZSM-5 catalyst which provides a high product yield in short
autoclavation time.
Summary of the invention
The present invention relates to the improved synthesis
of uniform porous, crystalline zeolitic material similar to ZSM-5 a member of pentasil
family. ZSM-5 has a characteristic X-ray diffraction pattern The typical chemical
composition of ZSM-5 may be represented as 3.25 Na2O: Al2O3:
30 SiO2: ∼958 H2O.
Accordingly the present invention provides an improved
process for the preparation of ZSM-5 catalyst of the formula 3.25 Na2O.
Al2O3.30SiO2.zH2O where z = 15-20 water
molecules per unit cell, and XRD pattern as given in Table 1 below comprising autoclaving
a mixture of a pre-prepared seeding gel comprising a mixture of a alkali metal cation,
an alkali hydroxide, and a silica source in water, and further amounts of silica
source and an aluminium source in the presence of an organic solvent near or above
the super critical conditions of temperature and pressure for the said organic solvent.
In one embodiment of the invention, the alkali metal cation
comprises sodium tetraalkyl ammonium cation.
In a further embodiment of the invention, the silica source
comprises tetraethoxysilane.
In another embodiment of the invention, the aluminium source
is sodium aluinate.
In one embodiment of the invention, the organic solvent
used is selected from the group consisting of methanol, acetone, isopropanol, acetonitrile
and ethanoL
In another embodiment of the invention, water is used as
a co-solvent along with the organic solvent.
In a further embodiment of the invention, the autoclavation
temperature is varied from 150 to 250°C, preferably under supercritical temperature
of organic solvent.
In yet another embodiment of the invention, the autoclavation
pressure is varied from 20 to 50 atm near to sub-critical and supercritical pressure
of the organic solvent used.
In another embodiment of the invention, the Si/Al atomic
ratio in the seeding gel is varied thereby controlling the Si/Al atomic ratio in
the as synthesized ZSM-5.
In a preferred embodiment the Si/Al ratio can be varied
in the range of 10 to 60. ZSM-5 is highly thermally stable. The organic template
was removed by heating as-synthesized ZSM-5 at 550°C for 12-16 hours.
Detailed description of the invention
The seeding gel was used in the initial geL The seeding
gel was typically prepared as follows: 0.6 g (0.01725 mole) of sodium hydroxide
was dissolved in 71.028 ml (3.946 mole) of distilled water. 27.7M1 (0.02875 mole)
of tetrapropylammonium hydroxide was added dropwise to NaOH solution with stirring.
The mixture was stirred for 30 min. Then 27.5 ml (0.1322 mole) of tetraethoxysilane
was added dropwise. The total mixture was stirred at 100°C for about 16 h.
This mixture was used as seeding gel. The ZSM-5 was synthesized as follows: Sodium
hydroxide of 0.88 g (o.22 mole) was dissolved in distilled water. Sodium aluminate
of 1.05 g (0.0128 mole) and 196 ml (4.841 mole) of methanol as a solvent were added
and the mixture was stirred for 30 min. Tetraethoxysilane of 41.9 ml (0.1882 mole)
was added dropwise and stirred for an hour. Finally 15 g of the seeding gel was
added and the mixture was stirred for 1 h. The initial pH of the mixture was 10.2-11.0.
The total mixture was put into 600 ml Parr autoclave and stirred at 230°-250°C
for 4-10 h. The solid product was filtered, washed with distilled water and dried
at 100-110°C for 6 h.
The organic template was removed by calcining at 550°C
for 12 h. The typical XRD pattern is given in Table 1. The ZSM-5 catalysts were
synthesized with the autoclavation temperature 230-250°C and the autoclavation
time 4, 6 and 10 h and the XRD patterns are given in Table 1, Table 2 and Table
3 respectively. The experimental conditions for the synthesis of ZSM-5 with various
solvents and high pressure conditions are given in Table 4. The experimental conditions
corresponding to the synthesis of ZSM-5 catalysts at various autoclavation temperatures
are given in Table 5.
EXAMPLE 1:
This example 1 illustrates the synthesis of ZSM-5 using
methanol and water as solvents. Sodium hydroxide of 0.88 g (0.22 mole), 1.05 g of
sodium aluminate, 41.9 ml (0.1882 mole) of tetraethoxy silane, 196 ml (4.841 mole)
of methanol and 15 g seeding gel as described earlier containing TPAOH were mixed
thoroughly. The initial pH of mixture was ~10.2. The gel composition was as follows,
(SiO2)29.4: (Al2O3)1: (Template)0.5:
(H2O)260. The mixture was put in the Parr autoclave and heated
at 242°C for 4 h. Then the solid material was filtered, washed thoroughly and
dried at 100-110°C for 6 h. The organic template was removed by calcining at
550°C for ~12 h. The XRD pattern is as given in Table 1. The crystallinity
was > 95%. The BET surface area was 361 m2.g-1.
EXAMPLE 2:
The synthesis of ZSM-5 was carried out as discussed in
Example 1, except that methanol is replaced by acetone as a solvent. The autoclavation
was carried out at 230°C and 47 atm autogeneous pressure for 10 h. The crystallinity
was ~74% and the BET-N2-surface area was 364 m2.g-1.
The XRD pattern of this catalyst is given in Table 6.
EXAMPLE 3:
The synthesis of ZSM-5 was carried out as discussed in
Example 1 except that methanol was replaced by isopropanol as a solvent. The autoclavation
was carried out at 230°C and 48 atm autogeneous pressure for 10 h. The crystallinity
was ~ 71% and the N2 BET surface area was 346 m2.g-1.
The XRD pattern of this catalyst is given in Table 7.
EXAMPLE 4:
The synthesis of ZSM-5 was carried out as discussed in
Example 1 except that methanol was replaced by ethanol as a solvent. The autoclavation
was carried out at 233°C and 50 atm autogeneous pressure for 10 h. The crystallinity
was ~53% and BET surface area using nitrogen was 343 m2.g-1.The
XRD pattern of this catalyst is given in Table 8.
EXAMPLE 5: COMPARATIVE:
The synthesis of ZSM-5 was carried out as discussed in
Example 1 except that methanol was replaced by water as the only solvent. The autoclavation
was carried out at 260°C and 47 atm autogeneous pressure for 10 h. The crystallinity
of the zeolite was ~83% and BET surface area using nitrogen was 379 m2
g-1. The XRD pattern of this ZSM-5 catalyst is given in Table 9.
EXAMPLE 6:
The synthesis of ZSM-5 was carried out as discussed in
Example 1 except that the autoclavation was carried out at 200°C and 39 atm
autogeneous pressure for 4 h, The crystallinity of the zeolite was ~94% and BET
surface area using nitrogen was 358 m2.g-1. The XRD pattern
of this ZSM-5 catalyst is given in Table 10.
Table 1: XRD pattern of ZSM-5 catalyst (solvent=CH<sub>3</sub>OH, autoclavation
time=4h)
d, Interplane spacing
Intensity ratio
11.290
51.9
10.090
34.0
7.500
7.0
6.763
5.1
6.397
10.3
6.042
12.1
5.746
6.1
5.594
6.9
5.020
5.2
4.633
6.9
4.277
9.5
4.022
7.3
3.854
100.0
3..741
39.4
3.658
23.5
3.453
9.3
3.356
10.6
3.060
8.4
2.993
13.5
2.742
5.6
2.687
6.1
2.687
7.4
2.492
8.8
2.408
5.6
Table 2: XRD pattern of ZSM-5 (solvent= methanol, autoclavation time= 6 h)
d, Interplaner spacing
Intensity ratio
23.47
15.1
19.25
18.3
13.76
14.3
11.30
58.3
10.08
46.5
9.05
9.0
7.49
11.6
7.13
11.1
6.74
11.3
6.41
20.6
6.03
20.1
5.60
42.2
5.38
11.3
5.02
12.0
4.62
14.9
4.27
43.8
4.0
17.5
3.85
100.0
3.74
84.5
3.66
66.2
3.43
43.5
3.35
31.8
3.15
5.5
3.06
10.0
2.98
12.8
2.92
8.3
2.79
4.6
2.68
7.3
2.60
4.5
2.50
6.2
2.46
7.3
2.4
10.1
Table 3: XRD pattern of ZSM-5 (solvent= methanol, autoclavation time= 10
h)
d, Interplaner spacing
Intensity ratio
13.99
1.3
11.53
84.2
10.29
44.8
7.589
6.8
6.828
7.3
6.479
13.7
6.102
20.2
5.807
7.8
5.668
7.9
5.457
6.7
5.065
9.6
4.678
5.4
4.423
7.0
4.309
10.8
4.079
7.1
3.890
100.0
3.775
55.4
3.683
30.3
3.471
15.0
3.166
10.1
3.076
11.5
3.007
20.3
2.756
8.2
2.622
9.5
2.418
7.0
2.338
6.3
The experimental conditions for the synthesis of ZSM-5
are given the Table 4.
Table 4: Synthesis of ZSM-5 with various solvents and under high pressure conditions.
Entry
Solvent
Gel Composition
Autoclavation Temperature (°C)
Autogeneous Pressure (atm)
Time (h)
Initial pH
Final pH
Surface area (m2.g-1)
% Crystallinity
(Si/Al) atomic zeolite
1
Methanol
R. (CH3OH)756
242
50
4
10.2
11.6
361
95.0
27.25
242
49
6
10.2
11.6
351
83.0
--
242
50
10
10.1
11.8
387
92.0
--
2
Acetone
R. (CH3COCH3)417
230
47
10
10.2
11.3
364
74.0
17.10
3
Isopropanol
R. ((CH3)2CHOH)400
230
48
10
10.3
11.4
346
71.0
17.63
4
Ethanol
R. (CH3CH2OH)525
233
50
10
10.3
11.6
343
53.0
17.63
5
Acetonitrile
R. (CH3CN)586
265
50
10
10.0
11.2
333
--
16.43
6
Water
R (H2O)1701
260
47
10
10.4
11.6
379
83.0
13.85
R = (SiO2)29.4,
(Al2O3)1, (Templ)0.5. (H2O)260
The autoclavation temperature and corresponding pressure
was varied and given in Table 5.
Table 5: Synthesis of ZSM-5<sup>a</sup>: Effect of Temperature
Entry
Autoclavation Temperature (°C)
Autogeneous Pressure (atm)
Gel Composition
Time (h)
Initial pH
Final pH
Surface area (m2.g-1)
% Crystallinity
1.
242
50
R. (CH3OH)756
4
10.2
11.6
361
95.0
2.
200
39
"
4
10.1
11.2
358
94.0
3.
180
34
"
4
9.9
11.0
342
95.0
4.
150
27
"
4
9.8
11.1
347
61.0
a: Methanol used as a solvent
R= (SiO2)29.4. (Al2O3)1.
(Templ)0.5. (H2O)260
Table 6: XRD pattern of ZSM-5 (solvent= acetone, autoclavation time =10 h)
d, Interplaner spacing
Intensity ratio
11.18
51.9
10.01
39.3
7.423
8.6
6.390
16.9
6.011
15.4
5.571
15.1
5.365
11.6
4.596
9.2
4.264
29.0
4.039
21.9
3.852
100.0
3.728
64.9
3.649
27.5
3.346
68.7
3.051
13.9
2.982
17.6
2.848
13.2
2.748
9.2
2.489
4.7
2.398
16.0
Table 7: XRD pattern of ZSM-5 (solvent= isopropanol, autoclavation time=
10 h)
d, Interplaner spacing
Intensity ratio
28.12
9.3
22.59
6.9
17.96
5.8
13.66
5.4
11.06
63.3
9.869
37.7
8.812
6.7
7.414
6.4
6.666
5.6
6.325
5.2
5.946
12.8
5.675
11.3
5.557
7.4
5.334
5.7
4.978
11.7
4.591
8.7
4.352
7.4
4.240
33.2
4.022
12.2
3.830
100.0
3.714
50.2
3.630
25.5
3.468
7.4
3.424
9.7
3.332
72.4
3.321
6.1
3.126
4.3
3.044
11.2
2.971
14.6
2.863
6.9
2.729
5.2
2.669
5.1
2.568
5.6
2.453
11.6
2.276
9.3
Table 8: XRD pattern of ZSM-5 catalyst (solvent= ethanol, autoclavation time=
10 h)
d, Interplaner spacing
Intensity ratio
11.12
49.4
9.936
37.8
6.369
16.5
5.991
17.8
5.616
15.8
4.999
9.9
4.592
11.2
4.253
44.2
4.035
98.2
3.836
100.0
3.723
55.2
3.630
25.3
3.454
9.3
3.341
65.1
3.138
16.9
3.049
15.2
2.978
26.2
2.848
17.8
2.742
11.4
2.478
18.5
Table 9: XRD pattern of ZSM-5 catalyst (solvent= water, autoclavation time=
10 h)
d, Interplaner spacing
Intensity ratio
11.48
73.1
10.26
55.6
9.186
6.9
7.605
6.3
6.805
7.2
6.476
11.7
6.074
14.7
5.657
14.9
5.425
8.8
5.055
9.1
4.658
9.3
4.307
12.5
4.042
7.6
3.883
100.0
3.762
50.6
3.683
28.3
3.480
10.7
3.362
16.7
3.075
16.4
3.002
15.5
2.877
7.6
2.757
8.2
2.506
9.6
2.418
7.7
2.300
5.8
2.016
13.1
1.917
6.4
1.817
7.0
Table 10: XRD pattern of ZSM-5 catalyst (solvent= methanol, autoclavation
temperature= 200°C)
d, Interplaner spacing
Intensity ratio
32.51
4.9
21.67
5.2
16.15
5.1
11.52
66.0
10.31
43.4
9.209
4.9
7.605
10.5
7.234
9.6
6.862
8.2
6.495
8.3
6.097
20.0
5.815
8.2
5.656
17.8
4.668
7.9
4.413
7.2
4.318
9.3
4.055
6.8
3.880
100.0
3.793
28.3
3.756
55.5
3.689
33.4
3.467
8.5
3.339
8.2
3.000
9.7
3.005
12.1
2.629
9.6
|
| Anspruch[de] |
Verfahren zur Herstellung eines ZSM-5 Katalysators mit der Formel 3,25
Na2O·Al2O3·30SiO2·zH2O,
in welcher z = 15-20 Wassermoleküle pro Einheitszelle darstellen, wobei das
Verfahren eine Autoklavbehandlung einer Mischung aus einem vorher zubereiteten Keimgel
aufweist, welch letzteres eine Mischung umfasst aus einem Alkalimetallkation, einem
Alkalihydroxid, und einer Kieselerdequelle in Wasser, und weiteren Mengen an Kieselsäurequelle
und an Aluminiumquelle in Anwesenheit eines organischen Lösungsmittels in der
Nähe oder oberhalb der superkritischen Bedingungen von Temperatur und Druck
für das organische Lösungsmittel.
Verfahren gemäß Anspruch 1, bei welchem der ZSM-5 Katalysator
ein XRD Muster aufweist, welches in der nachfolgenden Tabelle dargelegt wird:
D, Netzebenenabstände
Intensitätsverhältnis
11,290
51,9
10,090
34,0
7,500
7,0
6,763
5,1
6,397
10,3
6,042
12,1
5,746
6,1
5,594
6,9
5,020
5,2
4,633
6,9
4,277
9,5
4,022
7,3
3,854
100,0
3,741
39,4
3,658
23,5
3,453
9,3
3,356
10,6
3,060
8,4
2,993
13,5
2,742
5,6
2,687
6,1
2,687
7,4
2,492
8,8
2,408
5,6
Verfahren gemäß Anspruch 1, bei welchem das Alkalimetallkation
ein Natriumtetraalkylammoniumkation aufweist.
Verfahren gemäß Anspruch 1, bei welchem die Kieselerdequelle
ein Tetraethoxysilan aufweist.
Verfahren gemäß Anspruch 1, bei welchem die Aluminiumquelle
ein Natriumaluminat aufweist.
Verfahren gemäß Anspruch 1, bei welchem das verwendete organische
Lösungsmittel ausgewählt wird aus der Gruppe bestehend aus Methanol, Aceton,
Isopropanol, Acetonitril und Ethanol.
Verfahren gemäß Anspruch 1, bei welchem Wasser zusammen mit
dem organischen Lösungsmittel als ein Co-Lösungsmittel verwendet wird.
Verfahren gemäß Anspruch 1, bei welchem die Temperatur der
Autoklavbehandlung von 150 bis 250 °C variiert, vorzugsweise unterhalb der
superkritischen Temperatur eines organischen Lösungsmittels.
Verfahren gemäß Anspruch 1, bei welchem der Druck der Autoklavbehandlung
von 20 bis 50 atm (2,03 bis 5,07 MPa) variiert.
Verfahren gemäß Anspruch 1, bei welchem das Si/Al Atomverhältnis
in dem Keimgel variiert wird, wodurch das Si/A1 Atomverhältnis gesteuert wird
in dem ZSM-5, so wie es synthetisiert worden ist.
Verfahren gemäß Anspruch 1, bei welchem das Si/Al Atomverhältnis
in dem Keimgel in dem Bereich von 10 bis 60 variiert wird.
Verfahren gemäß Anspruch 1, bei welchem die organische Matrix
entfernt wird durch ein Erhitzen des ZSM-5, so wie es synthetisiert worden ist,
bei 550 °C während einer Zeitdauer von 12-16 Stunden.
|
| Anspruch[en] |
A process for the preparation of ZSM-5 catalyst of the formula 3.25
Na20. Al2O3.3OSiO2.zH2O where
z = 15-20 water molecules per unit cell comprising autoclaving a mixture of a pre-prepared
seeding gel comprising a mixture of an alkali metal cation, an alkali hydroxide,
and a silica source in water, and further amounts of silica source and an aluminium
source in the presence of an organic solvent near or above the super critical conditions
of temperature and pressure for the said organic solvent.
A process as claimed in claim 1 wherein the ZSM - 5 catalyst has an
XRD pattern given in the table below:
D, Interplaner spacing
Intensity ratio
11.290
51.9
10.090
34.0
7.500
7.0
6.763
5.1
6.397
10.3
6.042
12.1
5.746
6.1
5.594
6.9
5.020
5.2
4.633
6.9
4.277
9.5
4.022
7.3
3.854
100.0
3.741
39.4
3.658
23.5
3.453
9.3
3.356
10.6
3.060
8.4
2.993
13.5
2.742
5.6
2.687
6.1
2.687
7.4
2.492
8.8
2.408
5.6
A process as claimed in claim 1 wherein the alkali metal cation comprises
sodium tetraalkyl ammonium cation.
A process as claimed in claim 1 wherein the silica source comprises
tetraethoxysilane.
A process as claimed in claim 1 wherein the aluminium source comprises
sodium aluminate.
A process as claimed in claim 1 wherein the organic solvent used is
selected from the group consisting of methanol, acetone, isopropanol, acetonitrile
and ethanol.
A process as claimed in claim 1 wherein water is used as a co-solvent
along with the organic solvent.
A process as claimed in claim 1 wherein the autoclavation temperature
is varied from 150 to 250°C, preferably under supercritical temperature of
organic solvent.
A process as claimed in claim 1 wherein the autoclavation pressure is
varied from 20 to 50 atm (2.03 to 5.07 MPa).
A process as claimed in claim 1 wherein the Si/A1 atomic ratio in the
seeding gel is varied thereby controlling the Si/Al atomic ratio in the as synthesized
ZSM-5.
A process as claimed in claim 1 wherein the Si/Al atomic ratio in the
seeding gel is varied in the range of 10 to 60.
A process as claimed in claim 1 wherein the organic template is removed
by heating as-synthesized ZSM-5 at 550°C for 12-16 hours.
|
| Anspruch[fr] |
Procédé pour la préparation du catalyseur ZSM-5 de la
formule 3,25Na2O·Al2O3·30SiO2·zH2O
où z = 15-20 molécules d'eau par cellule élémentaire comprenant
le passage à l'autoclave d'un mélange d'un gel d'ensemencement pré-préparé
comprenant un mélange d'un cation de métal alcalin, d'un hydroxyde alcalin
et d'une source de silice dans de l'eau, et d'autres quantités de source de
silice et d'une source d'aluminium en présence d'un solvant organique près
ou au-dessus des conditions supercritiques de température et de pression pour
ledit solvant organique.
Procédé suivant la revendication 1, dans lequel le catalyseur
ZSM-5 possède un diagramme XRD donné dans le tableau ci-dessous:
D, espacement interplanaire
Rapport d'intensité
11,290
51,9
10,090
34,0
7,500
7,0
6,763
5,1
6,397
10,3
6,042
12,1
5,746
6,1
5,594
6,9
5,020
5,2
4,633
6,9
4,277
9,5
4,022
7,3
3,854
100,0
3,741
39,4
3,658
23,5
3,453
9,3
3,356
10,6
3,060
8,4
2,993
13,5
2,742
5,6
2,687
6,1
2,687
7,4
2,492
8,8
2,408
5,6
Procédé suivant la revendication 1, dans lequel le cation
de métal alcalin comprend un cation de tétraalkylammonium de sodium.
Procédé suivant la revendication 1, dans lequel la source
de silice comprend un tétraéthoxysilane.
Procédé suivant la revendication 1, dans lequel la source
d'aluminium comprend un aluminate de sodium.
Procédé suivant la revendication 1, dans lequel le solvant
organique utilisé est choisi dans le groupe constitué de méthanol,
d'acétone, d'isopropanol, d'acétonitrile et d'éthanol.
Procédé suivant la revendication 1, dans lequel l'eau est
utilisée comme un co-solvant accompagné du solvant organique.
Procédé suivant la revendication 1, dans lequel la température
du passage à l'autoclave est variée de 150 à 250°C, de préférence
en dessous de la température supercritique du solvant organique.
Procédé suivant la revendication 1, dans lequel la pression
du passage à l'autoclave est variée de 20 à 50 atm (de 2,03 à
5,07 MPa).
Procédé suivant la revendication 1, dans lequel le rapport
atomique de Si/Al dans le gel d'ensemencement est varié, régulant ainsi
le rapport atomique de Si/Al dans ZSM-5 tel que synthétisé.
Procédé suivant la revendication 1, dans lequel le rapport
atomique de Si/Al dans le gel d'ensemencement est varié dans l'intervalle de
10 à 60.
Procédé suivant la revendication 1, dans lequel la matrice
organique est retirée en chauffant ZSM-5 tel que synthétisé à
550°C pendant 12-16 heures.
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