Note: Descriptions are shown in the official language in which they were submitted.
-
2 ~ 6 7 ~ ~ PCT~4/02457
"Process for the Manufacture of a Zeolite"
This invention relates to a process for the
manufacture of a zeolite, especially to one suitable for
use as a catalyst, to the zeolite produced by the
process, and to organic reactions, especially oxidations
of hydrocarbons, catalysed thereby.
Titanium-containing TS-l and TS-2 are catalysts for
the oxidation of hydrocarbons by hydrogen peroxide. A
disadvantage of these catalysts is that because they have
MFI and MEL structures, respectively, the rings of which
are 10-membered, of diameter of the order of 0.5 nm, the
entry of bulky feed molecules is restricted. For
example, in the oxidation of paraffins, n-hexane reacts
more readily than cyclohexane, and in general reactivity
decreases with increasing branching and molecular weight.
Further, the activity of the catalysts is high only for
hydrogen peroxide; for organic hydroperoxides they are
much less efficient.
More recently, a titanium-containing zeolite capable
of efficiently catalysing the oxidation of higher
paraffins using hydrogen peroxide has been synthesized
This catalyst, Ti-Beta zeolite, has a pore diameter of
about 0.75 nm, and may be prepared as described in ~.
Chem. Soc. Chem. Comm., 8, 1992, 589, using a procedure
in which low concentrations of aluminium are present in
the synthesis mixture.
WOg5/03~9 PCT~4/02457 -
~67 2~ ~ - 2 -
In our co-pending Application No- 9307910, a process
is described for the manuf~acture of Ti-Beta zeolite which
comprises the preparation of a,synthesis mixture
containing a source of titanium (e.g., tetraethyl
orthotitanate, hereinafter TEOT), a source of aluminium
(e.g., aluminium~powder), a source of silicon (e.g.
colloidal silica) and an organic nitrogen-containing base
(especially tetraethylammonium hydroxide, hereinafter
TEAOH), ageing the mixture, advantageously in the
presence of H2O2, and hydrothermal treatment of the aged
mixture.
The crystals formed during hydrothermal treatment
are isolated, washed, dried, and calcined to remove
organic material from the structure. Typical synthesis
mixtures yielding Ti-Beta zeolite after hydrothermal
treatment have an initial molar composition within the
following ranges:
SiO2tl); Tio2 (0.0001 to 0.2~; A12O3 (0.005 to 0.100)
H2O (10 to 100); and TEAOH (0.1 to 1)
Advantageously the Ti plus Si:Al molar ratio is
within the range of from 10 to 200:1. Hydrogen peroxide
is advantageously present in the synthesis mixture,
although it may decompose before or during hydrothermal
treatment, preferably in a proportion of 10 to 200 moles
H2O2 per mole of TEOT when that is used as the source of
titanium.
The catalyst formed in accordance with this
~ 095/03~9 2 ~ ~ 7 ~ ~ ~ PCT~4/02457
procedure is active for oxidations using organic
peroxides, especially hydroperoxides, thereby enabling
the oxidation reaction to take place in a single organic
phase, avoiding the aqueous phase also present when H22
is employed.
Although the procedure described above produces an
active catalyst, yields in the absence of alkali metal
cations are very low. Indeed, in an article by Camblor
et al, Zeolites, 1991, 202 to 210, it is suggested that
alkali metal cations are essential for the formation of
zeolite Beta itself, and there would have appeared to be
no reason to distinguish Ti-Beta in this respect.
The present invention is based on the observation
that if ethene is present in contact with a Ti-, V-, or
Zr-Beta-forming synthesis mixture during the
hydrothermal treatment the corresponding Ti-, V-, or Zr-
Beta zeolite is obtained in good yields.
The present invention accordingly provides in a
first aspect a process for the manufacture of a Ti-, V-,
or Zr-Beta zeolite in which at least a part of a
hydrothermal treatment of a Ti-, V-, or Zr-Beta forming
synthesis mixture is carried out under an ethene-
containing atmosphere at a pressure of at least 20 bar
and advantageously under an ethene partial pressure of at
least 5 bar.
In a second aspect, the invention provides a process
for the manufacture of a Ti-, V-, or Zr-Beta zeolite in
WO9~/03~9 PCT~4/02457
2 1 6~
which at least a part of a hydrothermal treatment of a
Ti-, V-, or Zr-Beta forming synthesis mixture is carried
out in the presence of at least O.1 mole of ethene per
mole of tetraethylammonium cations. Advantageously, the
mole ratio of ethene:tetraethylammonium is in the range
O.l to 1:1.
For clarity, the remainder of the description will
primarily relate to the aspect of the invention in which
the product is Ti-Beta zeolite; it will be understood
that mutatis mutandis the same procedure is used for the
other products. It will be understood also that it is
within the scope of the invention to make products
containing mixtures of two or more of Ti, V, and Zr, as
well as zeolites containing one or more of Ti, V, or Zr,
and small proportions of other cations.
As a Ti-Beta forming synthesis mixture, there is
typically used a mixture comprising a source of silicon,
a source of titanium, a source of aluminium, water, and a
source of tetraethylammonium cations.
The synthesis mixture is advantageously
substantially free from alkali metal cations; by
substantially free is meant the absence of more alkali
metal than is inevitably present in commercial supplies
of the essential components. If alkali metal ions,
e.g., sodium or potassium ions, are present, they are
advantageously present in a molar proportion of Sio2:M+
of 1: at most 0.5.
~ O9~/03~9 PCT~ ~4/02457
~ ~ ~72~
Advantageously, the synthesis mixture has a molar
composition within the following ranges:
SiO2(1); TiO2(0.0001 to 0.2); A12O3(0.0005 to 0.1);
H2O(10 to 100) and TEAOH (0.01 to 1).
Advantageously, the Ti plus Si:Al molar ratio is
within the range of from 50 to 200:1.
Preferred sources of the components are: for
silicon, colloidal silica, advantageously a colloidal
silica substantially free from alkali metal cations, or a
tetraalkylammonium orthosilicate; for aluminium,
aluminium powder; and for titanium, a hydrolysable
titanium compound, e.g., TiOC14, TiOC12 or a tetraalkyl
orthotitanate, especially TEOT. For vanadium, a
preferred source is vanadyl sulphate and, for zirconium,
zirconyl sulphate. The tetraethyl ammonium cations are
advantageously provided by TEAOH.
Advantageously, at least for titanium, hydrogen
peroxide is present in the synthesis mixture.
Advantageously, it is present in a proportion of from 10
to 200 moles per mole of TEOT, when that is the titanium
source.
Advantageously, especially if it contains hydrogen
peroxide, the synthesis mixture is aged between its
formation and the hydrothermal treatment. Ageing may be
carried out at room temperature or at elevated
temperatures, for example at from 60 to 90C,
advantageously about 70C, the ageing time being from 2
W095/03W PCT~4/02457 -
2~ 2~ ~ - 6 -
to 24 hours, depending inversely on the temperature. A
preferred ageing treatment comprises initial room
temperature ageing for from 12 to 18 hours, followed by
elevated temperature ageing, e.g., at 70C, for from 2 to
4 hours.
Elevated temperature ageing also causes evaporation
of water from the synthesis mixture, thereby producing a
synthesis gel of a concentration advantageous for
hydrothermal treatment. If desired, or required, the
aged gel may be diluted before treatment, e.g., with
ethanol. If ethanol is added, it is advantageously
present in the synthesis mixture subjected to hydro-
thermal treatment in a proportion of at most 2 moles per
mole of SiO2.
The synthesis mixture, preferably aged, is
advantageously subjected to hydrothermal treatment at a
temperature within the range of from 120C to 200C,
preferably from 130C to 150C, under the pressure regime
as indicated above, advantageously for a time in the
range of from 1 hour to 30 days, preferably from 6 days
to 15 days, until crystals are formed. Hydrothermal
treatment is advantageously effected in an autoclave.
While not wishing to be bound by any theory, it is
believed that under the conditions prevailing under the
hydrothermal treatment tetraethylammonium ions decompose
and are unavailable to form a template effective in
zeolite formation. By carrying out the treatment in the
~ 095/03~9 PCT~4/02457
2167~
presence of ethene, a decomposition product, the
equilibrium of the decomposition reaction is displaced
and more tetraethylammonium ions remain available to act
as templates.
In any event, by carrying out at least part of the
hydrothermal treatment in the presence of ethene, a
higher zeolite yield may be obtained or a lower
proportion of tetraethylammonium ions may be included in
the synthesis mixture. Advantageously, ethene is
present in the reaction vessel from the commencement of
the hydrothermal treatment.
Advantageously, the ethene partial pressure is at
least 5 bar, preferably at least 20 bar, and most
preferably at least 30 bar, for at least a part of the
period of hydrothermal treatment. Also, advantageously,
the total pressure is at least 30 bar, and preferably at
least 40 bar. Advantageously, the ethene partial
pressure is at least 80%, preferably at least 90~, of the
total pressure.
After crystallization has taken place, the synthesis
mixture is cooled, and the crystals are separated from
the mother liquor, washed and dried.
To eliminate the organic base from the crystals,
they are advantageously then heated to from 200 to 600C,
preferably about 550~C, in air, for from 1 to 72 hours,
preferably about 12 hours.
The resulting calcined product may either be used as
WOg5/03~9 PCT~4/02457 ~
2 l 67 ~
such or subjected to further treatment e.g., by acid,
for example, HCl, or by bases e.g., ammonium or sodium
ions. The product may be post-treated, as by steaming.
The Ti-Beta zeolite produced by the process of the
invention may be highly crystalline and is characterized
by an IR absorption at + 960 cm~1 and by an absorption
band in Diffuse Reflectance Spectroscopy at the wave
number 47,500 cm~1. Diffuse Reflectance Spectroscopy is
described in chapter 4 of "Characterisation of
Heterogeneous Catalysts" by Chemical Industries, Volume
15, published by Manel Dekker Inc. of New York in 1984.
The system used was as shown in Figure 3 of that chapter
using a Cary 5 spectrometer.
The zeolite produced by the process of the invention
is an active oxidation catalyst, especially for reactions
employing a peroxide as oxidant, including organic
peroxides, including hydroperoxides, as well as hydrogen
peroxide. compared to TS-1 and TS-2 catalysts, Ti-Beta
zeolite is more effective in the oxidation of larger
molecules, e.g., cycloparaffins and cycloolefins. The use
of organic hydroperoxides avoids the two phase system
necessarily associated with aqueous hydrogen peroxide.
The present invention accordingly also provides the
use of the product of the process of the invention as a
catalyst in the oxidation of an organic compound,
especially in single phase oxidation by an organic
peroxide.
~ 095/03~9 PCT~4/02457
~1 672~
The catalyst of the invention is effective in
oxidizing saturated hydrocarbons, e.g., paraffins and
cycloparaffins, and the alkyl substituents in alkyl-
aromatic hydrocarbons. In cycloparaffins, ring-opening
and acid formation may take place, for example, in the
oxidation of cyclohexane by tertiary butyl peroxide or
H22 adipic acid is produced, and in the oxidation of
cyclopentane glutaric acid is produced. The catalyst is
also effective in the epoxidation of unsaturated
hydrocarbons, e.g,. olefins and dienes, and the produc-
tion of ether glycols, diols, the oxidation of alcohols,
ketones or aldehydes to acids, and the hydroxylation of
aromatic hydrocarbons.
In the oxidation process of the invention the
oxidizing agent may be, for example, ozone, nitrous
oxide, or preferably hydrogen peroxide or an organic
peroxide including a hydroperoxide. Examples of suitable
organic hydroperoxides include di-isopropyl benzene
monohydroperoxide, cumene hydroperoxide, tert.butyl
hydroperoxide, cyclohexyl hydroperoxide, ethylbenzene
hydroperoxide, tert.amyl hydroperoxide, and tetralin
hydroperoxide. Advantageously the compound to be
oxidized is liquid or in the dense phase under the
conditions used for the reaction. Advantageously, the
reaction is carried out in the presence of a suitable
solvent. The use of a tertiary butyl hydroperoxide is
particularly beneficial since the tertiary butyl alcohol
W095/03~9 PCT~4102457 -
27~ - 10 -
produced can readily be converted to the valuable
isobutylene molecule.
The oxidation reaction may be carried out under
batch conditions or in a fixed bed, and the use of the
heterogeneous catalyst facilitates a continuous reaction
in a monophase or biphase system. The catalyst is stable
under the reaction conditions, and may be totally
recovered and reused.
The following Examples illustrate the invention.
Exam~le l
Mixture A was prepared by adding dropwise 3.4 ml
TEOT to 63.39 ml distilled H2O. The mixture is cooled to
5OC, and 39 ml H2O2 (35~ in H2O) added. The resulting
mixture was stirred for 2 hours at 5OC, resulting in a
clear yellow-orange liquid.
Mixture B was prepared by adding 0.0312 g Al powder
to 28.71 g of TEAOH (40% in H2O) and dissolving it by
heating to 90C. After cooling 31 ml of distilled H2O
were added. This mixture was cooled to 5C and added to
mixture A. The resulting mixture was stirred for
another hour, then 12.23 g colloidal silica (Ludox HS40,
40% in water, stabilized by Na~) added. The synthesis
mixture was stirred overnight at room temperature,
followed by heating for 4 hours at 70C. The resulting
concentrated gel was diluted with 10 ml of ethanol,
transferred to a stainless steel autoclave and made up to
100 ml with water.
~ 095/03~9 PCT~4/024S7
~ ~7f2~
After 6 days at 125C, the contents of the autoclave
were a milk white suspension. This was centrifuged at
4000 rpm for 20 minutes to separate the solids. After
drying at 60C, the solids were calcined at 550OC in air
for 12 hours to yield a Ti-Beta zeolite. More details of
synthesis conditions for this and the remaining Examples
are given in Table 1, while characteristics of the
zeolites produced are given in Table 2.
In a Comparison Example l, the procedure was as
given above except that following addition of colloidal
silica the synthesis mixture was immediately placed in
the autoclave and heated for 7 days at 150C. An
amorphous product resulted.
ExamPle 2
Mixture A was obtained by adding dropwise 0.5 ml
TEOT to 63 ml distilled H2O. This mixture was cooled to
5C. Subsequently, 39 ml H2O2 (35% in H20) were added.
The resulting mixture was stirred for 3 hours at 5C,
resulting in a clear yellow-orange liquid.
Mixture B was produced by adding 0.0312 g Al powder
to 29 . 43 g of TEAOH (40% in H2O) and dissolvlng it by
heating at 900C. Then, 31 ml of distilled H2O were
added. This mixture was cooled to 5C.
Solutions A and B were mixed and the resulting
solution stirred for 1 hour at 5C. Subsequently,
12. 54 g of colloidal silica (Ludox AS40, 40% in H2O,
stabilized by NH4+) were added. This mixture was stirred
W095/03~9 PCT~4/02457 -
2i~ 2~ ~ - 12 -
at room temperature for 18 hours and afterwards for
another 2 hours at 70C. The resulting gel was diluted
with 10 ml ethanol and transferred to a stainless steel
autoclave.
The autoclave was put in an oven and crystallization
proceeded without agitation at 125C for 6 days. After
this time the autoclave was quickly cooled to room
temperature and the solids separated from the liquid by
centrifugation at 13,000 rpm. The organic template was
then removed from the zeolite pores by calcination at
550C in air for 12 hours.
Example 3
63 ml of H2O were mixed with 1.5 ml TEOT. The
resulting mixture was cooled to 5C. During this time a
white suspension was formed. Subsequently, 39 ml of
precooled H2O2 (35 wt% in H20) were added to this
suspension. Upon addition the suspension took on a
yellow colour. The resulting solution (mixture A) was
stirred at 5C for 3 hours.
0.0315 g of Al powder and 29.42 g of TEAOH (40% in
H20) were put in a beaker, covered to prevent evaporation
and heated at 80C for 3 hours. After all the Al had
dissolved, 32.31 g of distilled H2O were added. The
resulting solution (Mixture B) was cooled to 5C.
Mixtures A and B were combined, resulting in a pale
yellow solution, which was kept stirred at 5C for
another hour. Afterwards, 12.53 g of colloidal silica
~ ogs/~g PCT~4/024S7
- 13 _ 2~ 7~i
(Ludox AS40, 40~ in H2O) were added. After 18 hours at
room temperature, the colour of the slightly opaque
solution had turned from pale yellow to white.
Subsequently, the solution was kept at 70C for 2 hours,
after which it was allowed to cool to room temperature.
The resulting gel was diluted with 10 ml of ethanol and
transferred to an autoclave.
The autoclave was kept in an oven at 135C in static
conditions. After 6 days the crystals were separated
13,000 rpm. Finally, the solids obtained were dried
overnight at 60C. The organic template was removed from
the zeolite pores by calcination at 550C in air for 12
hours.
ExamPle 4
Mixture A was obtained by adding dropwise 1.5 ml
TEOT to 63 ml distilled H2O. This mixture was cooled to
5OC. Subsequently, 39 ml H22 (35~ in H2O) were added.
The resulting mixture was stirred for 3 hours at 5C,
resulting in a clear yellow-orange liquid.
Mixture B was produced by adding 0.910 g Al powder
to 29.43 g of TEAOH (40~ in H2O) and dissolving it by
heating at 90C. Then, 31.08 g of distilled H2O were
added. This mixture was cooled to 5C.
Solutions A and B were mixed and the resulting
solution stirred for 1 hour at 5C. Subsequently,
12.57 g of colloidal silica (Ludox AS40, 40~ in H2O) were
added. This mixture was stirred at room temperature for
WO9~/03~9 PCT~4/02457 -
Z~ 14 -
16 hours and afterwards for another 2 hours at 70C. The
resulting gel was diluted with 10 ml ethanol and
transferred to a stainless steel autoclave.
The autoclave was put in an oven and the
crystallization proceeded without agitation at 135C for
10 days. After this time the autoclave was quickly
cooled to room temperature and the solid material
separated from the liquid by centrifugation at
13,000 rpm. After drying at 60C, the organic template
was removed from the zeolite pores by calcination at
550C in air for 12 hours.
Exam~le 5
12 ml of TEOT were mixed with 256 g of distilled
H2O. The resulting mixture was cooled to 5C. During
this time a white suspension formed. Subsequently, 103
ml of H2Oz (35 wt% in H2O) were added to this suspension.
Upon addition the suspension became yellow. The
resulting solution was stirred for 3 hours at 5C.
The aluminium source, 0.3859 g Al powder and 366 g
of TEAOH (40% in H2O) were combined in a beaker, covered
to prevent evaporation, and heated at 80C for 2 hours.
After dissolution of aluminium, 183 ml of distilled water
were added. The resulting solution was cooled to 5C.
The two solutions were mixed, resulting in a pale
yellow solution, which was stirred at 5C for another
hour. Afterwards, 61 g of colloidal silica (Aerosil,
200 m2/g) are added. After 18 hours at room temperature,
~ 095/03~9 PCT~ ~4/0~57
2~ ~:7~7~
- 15 -
the colour of the slightly opaque sol~tion turned from
pale yellow to white. Subsequently, the solution was
kept at 70C for 2~ hours, during which it became yellow
again. The solution was allowed to cool to room
temperature. Before transferring the solution to a
1000 ml, ptfe-lined, stainless steel autoclave, 61 ml of
ethanol were added. In previous Examples, the synthesis
mixture had occupied at most two-thirds of the autoclave
volume. In this Example, the synthesis mixture occupied
about 95% of the volume. Gas phase analysis showed a
high ethene content in the head-space.
The autoclave was kept at 140C without agitation.
After 11 days, pressure had risen to 50 bar. The
crystals were separated from the mother liquor and washed
by centrifugation at 13,000 rpm. After drying at 60C,
the organic template was removed from the zeolite pores
by calcination at 550C in air for 12 hours.
Example 6
The same procedure as described for Example 5 was
used to compose the synthesis gel, but all reagent
quantities were halved. The gel was transferred to a
lOoo ml, ptfe-lined, stainless steel autoclave, and
occupied about 50% of the volume. After closing the
autoclave, ethene was introduced to give an ethene
pressure of 7 bar. Subsequently, the autoclave was
heated to 140C. After 18 hours the pressure had risen
to 14 bar. It was increased to 34 bar by introducing
WOg5/03~9 PCT~4102457
2 ~6~ Z~ ~ - 16 -
further ethene into the autoclave. Finally, after 3
days, the pressure which had risen to 36 bar was
increased to 44 bar by adding further ethene. At this
stage, the molar ratio of ethene:TEAOH was about 0.4:1.
After a total of 13 days (when ~ressure was 50 bar) the
autoclave was quickly cooled down. The crystals were
separated from the mother liquor and washed by
centrifugation at 13,000 rpm. After drying at 60C, the
organic template was removed from the zeolite pores by
calcination at 550C in air for 12 hours.
Comparison ExamPle 2
The synthesis was as reported by M.A. Camblor et
al, J. Chem. Soc. Chem. Comm. 8 (1992) 589.
33.95 g of TEAOH (40% in H2O) were diluted with
40.00 g of distilled H2O, to which 0.9 ml of TEOT were
added. A white precipitate was formed. Subsequently,
9.99 g of colloidal silica (Aerosil 200 m2/g) were added.
Finally, a solution of 0.32 g of Al(NO3)3.9H2O in 6.01 g
distilled H2O was added.
The resulting gel was transferred to a ptfe-lined
stainless steel autoclave and kept at 13SC for 10 days,
while rotating at 50 rpm. The autoclave was quickly
cooled down. The crystals were separated from the mother
liquor and washed by centrifugation at 13,000 rpm. After
drying at 60C, the organic template was removed from the
zeolite pores by calcination at 550C in air for 12
hours.
~ 095/03249 PCT~4/02457
2 ~ 7 ~
- 17 -
Com~arison ExamPle 3
Example 2 was repeated at a SiO2/A12O3 mole ratio of
101:1 and 1.49 moles TEAOH per mole of sio2. No solids
were obtained.
WO 95/03249 1 PCT/EW4/02457--
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W095/03W PCT~4/02457 ~
~ ~ ~7 ~ 20 -
The results of Tables 1 and 2 show, with reference
to Comparison Example 1 and Example 1, the importance of
ageing the synthesis mixture before the hydrothermal
treatment. The IR of Comparison Example 1 showed neither
the typical zeolite-~ framework vibrations at 575 and
525 cm~l nor the Ti=o vibration at 960 cm~1, x-ray
diffraction (XRD) indicating the absence of
crystallinity. Under DRS examination, the bands at
30,800 cm~l, assigned to agglomerated Tio2~ and
34,000 cm~1, assigned to finely dispersed Tio2, were both
strong. In contrast in Example 1, carried out with
ageing, all the above-mentioned IR bands were present,
although the 960 cm~l was weak, and while the above-
mentioned DRS bands were present, they were weak, and
were accompanied by a strong band at 47,500 cm~l,
assigned to titanium in the framework of the zeolite.
The yield, at 4% was, however, very low, yield being
calculated as follows:
Yield % = 100 (weiqht of calcined zeolite obtained)
weight of SiO2 and A12O3 in gel
In Example 2, an NH4+ stabilized silica source is
used; a much higher yield, 20%, is obtained, and the DRS
bands attributable to the Tio2 phase are absent.
In Example 3, with a higher titanium content and
higher temperature and longer time of crystallization, an
improved yield (35%) is obtained.
~ og5/03~9 PCT~P94/02457
2~
- 21 -
In Example 4, a higher yield (75%) results from a
higher aluminium content, but a strong band at
34,000 cm~l indicates Tio2 present, possibly indicating
co-formation of Al-B, Al-Rich Ti-B and Tio2.
In Examples 5 and 6, a high ethene pressure is
maintained, in Example 5, by a small head-space and in
Example 6 by ethene addition during crystallization.
High yields are obtained with no indication of TiO2
contamination.
In Comparative Example 2, the absence of the band at
47,500 cm~1 and the presence of the other two DRS bands
indicate that a substantially different structure of
Ti-~ zeolite is being achieved by the process of the
present invention from that of the reported procedure.
Overall, the results show that the optimum synthesis
has the following characteristics:
a high ethene pressure;
synthesis gel ageing;
peroxide presence;
absence of alkali metal cations; and
low aluminium content.
