Molecular sieve abstract
The present invention relates to a titanium-silicalite (TS-1) molecular
sieve and the method for preparation of the same, wherein each crystallite
of said titanium-silicalite molecular sieve has a hollow cavity
with a radial length of 5-300 nm. The benzene adsorption capacity
of the molecular sieve determined at 25.degree. C. and P/P.sub.0=0.10
for 1 hour is at least 70 mg/g; and the method for preparation of
said molecular sieve comprises an acid-treatment and then an organic-base
treatment of the synthesized TS-1 molecular sieve, or only an organic-base
treatment. The TS-1 molecular sieve of the present invention has
a relatively high reactivity and activity stability in the catalytic
oxidation.
Molecular sieve claims
1. A titanium-silicalite molecular sieve with MFI structure, characterized
in that each crystallite of said molecular sieve has a hollow cavity.
2. A titanium-silicalite molecular sieve according to claim 1
wherein the radial length of said cavity in the hollow crystallite
is 5-300 nm.
3. A titanium-silicalite molecular sieve according to claim 1
wherein the benzene adsorption capacity of said molecular sieve
determined at 25.degree. C. and P/P.sub.0=0.10 for 1 hour is at
least 70 mg/g.
4. A molecular sieve according to claim 1 wherein the grains of
said molecular sieve are composed of individual hollow crystallites
or aggregated crystallites resulting from aggregation of the hollow
crystallites.
5. A method for preparation of said molecular sieve claimed in
any one of claims 1-4 comprising mixing the synthesized MFI-type
titanium-silicalite molecular sieve with an aqueous organic base
solution homogenously, then subjecting the resultant mixture to
a base-treatment in an autoclave at 120-200.degree. C. under autogenous
pressure for 1-192 hours, and recovering the resultant product.
6. A method according to claim 5 wherein said organic base is
selected from a group consisting of aliphatic amines, alkylol amines,
quaternary ammonium bases or mixtures thereof.
7. A method according to claim 6 wherein said aliphatic amines
have a general formula of R.sup.2(NH.sub.2).sub.n, wherein R.sup.2
represents a C.sub.1-6-alkyl, and n is 1 or 2.
8. A method according to claim 7 wherein said aliphatic amine
is selected from the group consisting of ethylamine, n-butyl amine,
butanediamine and hexane diamine.
9. A method according to claim 6 wherein said alkylol amines have
a general formula of (HOR.sup.3).sub.mN, wherein R.sup.3 represents
a C.sub.1-4-alkyl, and m is from 1 to 3.
10. A method according to claim 9 wherein said alkylol amine is
selected from monoethanolamine, diethanolamine or triethanolamine.
11. A method according to claim 6 wherein said quaternaryammonium
bases have a general formula of R.sup.4.sub.4NOH, wherein R.sup.4
represents a C.sub.1-4-alkyl.
12. A method according to claim 11 wherein said quaternaryammonium
base is tetrapropyl-ammonium hydroxide.
13. A method according to claim 5 wherein the ratio of molecular
sieve, organic base and water is: molecular sieve (g):organic base
(mol.):water (mol)=100:(0.0050-0.50):(5-200).
14. A method according to claim 13 wherein the ratio of molecular
sieve, organic base and water is: molecular sieve (g):organic base
(mol.):water (mol)=100:(0.010-0.15):(20-80).
15. A method according to claim 5 wherein the base-treatment is
carried out at 150-180.degree. C. under autogenous pressure for
2-120 h.
16. A method according to claim 5 further comprising repeating
said steps once or several times.
17. A method according to claim 5 further comprising mixing the
synthesized MFI-type of titanium-silicalite molecular sieve with
an acidic compound and water homogenously, and heating the mixture
at 5-95.degree. C. for 5-360 min, before the organic-base-treatment.
18. A method according to claim 17 wherein said acidic compound
is selected from organic aliphatic acids having a general formula
of R.sup.1(COOH).sub.n, wherein R.sup.1 represents a C.sub.1-4-alkyl,
and n is 1 or 2.
19. A method according to claim 17 wherein said acidic compound
is selected from inorganic acid compounds including hydrochloric
acid, sulfuric acid, phosphoric acid, nitric acid and/or hydrofluoric
acid.
20. A method according to claim 17 wherein said acidic compound
is selected from acidic salt compounds including ammonium chloride,
ammonium phosphate, ammonium nitrate, ammonium sulfate and/or ammonium
fluoride.
21. A method according to claim 17 wherein the ratio of molecular
sieve, acidic compound and water is: molecular sieve (g):acidic
compound (mol):water (mol)=100:(0.010-2.0):(5-250).
22. A method according to claim 18 wherein the ratio of molecular
sieve, acidic compound and water is: molecular sieve (g):acidic
compound (mol):water (mol)=100:(0.080-0.80):(10-100).
23. A method according to claim 17 wherein said acid-treatment
is carried out at 15-60.degree. C. for 10-180 min.
Molecular sieve description
FIELD OF THE INVENTION
[0001] The invention relates to a titanium-silicalite molecular
sieve and the method for the preparation of the same, specifically
to a five-member ring titanium-silicalite molecular sieve with MFI
structure (TS-1) and the method for preparation of the same.
BACKGROUND OF THE INVENTION
[0002] A crystalline titanium-silicalite molecular sieve is a novel
heteroatom substituted silicalite molecular sieve, which was first
reported in 1980s'. Now, a variety of titanium-silicalites have
been reported, including TS-1 with MFI structure, TS-2 with MEL
structure and TS-48 with a larger pore system. These molecular sieves
can be applied to catalytic oxidation of different organic substrates,
for example, epoxidation of olefins, hydroxylation of aromatics,
oximation of cyclohexanol and oxidation of alcohols, and exhibit
an excellent reactivity and selectivity in these catalytic oxidations.
These crystalline titanium-silicalites used as redox molecular sieve
catalysts have a prosperous future for applications in some industrial
processes.
[0003] TS-1 molecular sieve is a synthetic, crystalline porous
material having a structure similar to ZSM-5 obtained by substituting
titanium for a partial silicon in the skeleton, which exhibits an
excellent catalytic reactivity and selectivity in different oxidations
attributed to coordination of the catalytic oxidation property in
titanium and shape selectivity effects in ZSM-5 structure. Compared
with the traditional oxidation reactions, H.sub.2O.sub.2 as the
oxidant in all the oxidations catalyzed by TS-1 has the advantage
of giving environmentally benign water as its by-product and operating
simply. Hence, TS-1 makes it possible to develop new industrial
processes.
[0004] Marco Taramasso et al first disclosed a process for synthesizing
TS-1 in 1981 (GB 2071071A, U.S. Pat. No. 4410501). In their
report, the preparation of TS-1 is based on the initial formation
of a reaction mixture containing a silica source, a titanium source,
an organic base (RN+) and/or an alkaline oxide(Me.sub.n/2O), followed
by hydrothermal crystallization in an autoclave at 130-200.degree.
C. for 6-30 days. The final product TS-1 is obtained after filtration,
washing, drying and calcination. The silicon source used is selected
from tetra-alkyl ortho-silicate, or colloidal SiO.sub.2 or an alkali
metal silicate, and the titanium source used is selected from hydrolyzable
titanium compounds, preferably Ti(OC.sub.2H.sub.5).sub.4. The organic
base used is preferably tetra-propyl ammonium hydroxide. The reaction
mixtures generally show a composition range in mol % as follows:
1 Generally Preferably SiO.sub.2/TiO.sub.2: 5.about.200 35.about.65
OH.sup.-/SiO.sub.2: 0.1.about.1.0 0.3.about.0.6 H.sub.2O/SiO.sub.2:
20.about.200 60.about.100 Me/SiO.sub.2: 0.about.0.5 0 RN.sup.+/SiO.sub.2:
0.1.about.2.0 0.4.about.1.0
[0005] Thangaraj et al. indicated that titanium-content in the
skeleton of the TS-1 molcular sieve synthesized by the above process
was very low, and disclosed a TS-1 molecular sieve synthesis method
for effectively increasing titanium content in the skeleton of the
synthesized TS-1 molecular sieve (Zeolite, 1992 Vol. 12 p943-950).
It was said that, by this method, the value of Si/Ti in the molecular
sieve prepared by Taramasso's method could be reduced from 39 to
20. Thangaraj's method comprises: adding an appropriate amount of
an aqueous solution of tetrapropyl ammonium hydroxide (TPAOH) into
a tetraethyl silicate solution with stirring for a certain period
of time to get the solution dissolved throughly, then adding an
isopropanol solution of tetrabutyl titanate slowly under viogrous
stirring to obtain a clear liquid mixture (said solution must be
added slowly dropwise to prevent the formation of white TiO.sub.2
precipitate due to quick hydrolysis of tetrabutyl titanate); after
stirring for 15 minutes, adding another appropriate amount of an
aqueous TPAOH solution slowly, then displacing alcohol in the reaction
mixture under 75-80.degree. C. for 3-6 hours, and afterwards transferring
the mixture into an autoclave to undergo hydrothermal crystallization
under 170.degree. C. for 3-6 days, and after drying to obtain the
TS-1 molecular sieve. In the process, the reaction mixture shows
a composition in molecular ratio as follows;
SiO.sub.2:(0.01-0.10)TiO.sub.2:0.36TPAOH:35H.sub.2O
[0006] Du et al in CN1167082A discloses a method for preparation
of a TS-1 molecular sieve, comprising: dissolving a titanium source
in an aqueous TPAOH solution, and mixing with solid silica gel pellets
homogeneously to obtain a reaction mixture, then undergoing hydrothermal
crystallization in an autoclave under 130-200.degree. C. for 1-6
days, and afterwards filtrating, washing, drying and calcining the
mixture by conventional processes.
[0007] The above-metioned methods in the prior art for synthesizing
the TS-1 molecular sieves have drawbacks mainly in that, in the
course of process, a relatively large portion of stagnant Ti is
formed as ex-skeleton Ti remaining in the pore channels of the molecular
sieves, this portion of ex-skeleton Ti cannot play an effective
role in the catalytic oxidation, but will cause decomposition of
the oxidant (H.sub.2O.sub.2). Consequently, the TS-1 molecular sieves
prepared by the above methods exhibit low catalytic oxidation activity,
and moreover, due to unstable content of ex-skeleton Ti, TS-1 molecular
sieves having good catalytic oxidation activity can hardly be obtained
steadily, so the TS-1 molecular sieves obtained are generally inferior
in activity stability, which handicaps the industrial application
of the TS-1 molecular sieve in the prior art.
DISCLOSURE OF THE INVENTION
[0008] The object of this invention is to provide a novel titanium-silicalite
molecular sieves (TS-1) with MFI structure, particularly having
a unique morphology of crystallite and showing good catalytic reactivity
and stability in oxidations. Another object of the invention is
to provide a method for the preparation of the said titanium-silicalite
molecular sieve.
[0009] The titanium-silicalite molecular sieve provided by the
invention is characterized by crystallites with hollow struture,
in which the hollow cavity of each crystallite has a radial length
in the range of 5.about.300 nm, preferable 10.about.200 nm. The
benzene adsorption capacity of said titanium-silicalite sample tested
at 25.degree. C. and P/P.sub.0=0.10 for 1 h is at least 70 mg/g,
preferably at least 80 mg/g.
[0010] Said titanium-silicalite molecular sieve provided by the
invention is also characterized by that the cavity shape of said
titanium-silicalite crystallite can be varied, such as in circular,
or rectangular, or irregularly polygonal, or irregularly circular,
or a combination of these shapes.
[0011] The grains of the titanium-silicalite molecular sieve with
MFI structure provided by the invention are composed of individual
hollow crystallites or aggregated crystallites as a result of aggregation
of the hollow crystallites.
[0012] Said titanium-silicalite molecular sieve provided by the
invention is also characterized by that there is an obvious hysteresis
loop between the low-temperature N.sub.2 adsorption isotherm and
desorption isotherm of said molecular sieve, while generally there
is not any hysteresis loop between those isotherms of the conventional
titanium-silicalite. The applicants in their research found that
the hysteresis loop is related to the hollow cavity structure in
the crystallites of said titanium-silicalite molecular sieve. The
bigger the hollow cavity in the crystallites, the larger the said
hysteresis loop.
[0013] The SiO.sub.2:TiO.sub.2 molar ratio of said titanium-silicalite
molecular sieve of the invention ranges from 5 to 500 preferably
from 10 to 200.
[0014] The first method for the preparation of said titanium-silicalite
molecular sieve provided by the invention comprises the following
steps:
[0015] (1) Mixing a sythesized TS-1 with an acidic compound and
water homogenously, and letting the mixture react at 5-95.degree.
C. for 5-360 min., preferably at 15-60.degree. C. for 10-180 min.
to obtain an acid-treated TS-1;
[0016] (2) Mixing the acid-treated TS-1 obtained in step 1 with
an organic base and water homogenously, then transferring the mixture
to a autoclave to react at 120-200.degree. C. under autogenous pressure
for 1-192 hr., preferably at 150-180.degree. C. under antogenous
pressure for 2-120 hr, then filtrating, washing, drying and calcining
the resultant to obtain the TS-1.
[0017] In the first method according to the present invention,
step 1 and step 2 may be repeated once or several times respectively,
or only step 2 is repeated once or several times, so as to further
enlarge the hollowness in the crystallites, reduce the amount of
ex-skeleton TiO.sub.2 and improve the catalytic reactivity of the
TS-1 molecular sieve.
[0018] Said TS-1 used in step 1 of the first method of the present
invention can be a synthesized TS-1 prepared by any method of the
prior art, which can be as-synthesized or calcined, i.e. with or
without an organic template, preferably calcined and with the organic
template removed.
[0019] Said acidic compound used in step 1 of the first method
is selected from organic acid compounds, such as an aliphatic acid
R.sup.1(COOH).sub.n, wherein R.sup.1 is a C.sub.1-4-alkyl, and n
is 1 or 2; or inorganic mineral acids, such as hydrochloric acid,
sulfuric acid, phosphoric acid, nitric acid and hydrofluoric acid;
or acidic salt compounds, such as ammonium chloride, ammonium phosphate,
ammonium nitrate, ammonium sulfate and ammonium fluoride; preferably
inorganic acid.
[0020] The ratio of molecular sieve to acidic compound to water
used in step 1 of the first method is: molecular sieve (g):acidic
compound (mol):water (mol)=100:(0.010-2.0):(5-250), preferably 100:(0.080-0.80):(10-100).
[0021] The organic base used in step 2 of the first method of the
present invention is selected from the group consisting of aliphatic
amines, alkylol amines, quaternary ammonium bases, or mixtures of
these compounds, preferably alkylol amines, or quaternary ammonium
bases or mixtures of these compounds; most preferably quaternary
ammonium bases or mixtures of the organic base and quaternary ammonium
bases.
[0022] Said aliphatic amines have a general formula of R.sup.2(NH.sub.2).sub.n,
wherein R.sup.2 is a C.sub.1-6-alkyl, and n is 1 or 2 preferably
ethyl amine, n-butyl amine, butanediamine, or hexanediamine.
[0023] Said alkylol amine compounds have a general formula of (HOR.sup.3).sub.mN,
wherein R.sup.3 is a C.sub.1-4-alkyl, and m is from 1 to 3 preferably
mono ethanolamine, diethanolamine or triethanolamine.
[0024] Said quaternary ammonium bases have a general formula of
R.sup.4.sub.4NOH, wherein R.sup.4 is a C.sub.1-4-alkyl, preferably
a C.sub.2-4-alkyl, more preferably propyl.
[0025] The ratio of molecular sieve to organic base to water used
in step 2 of the first method is: molecular sieve (g):organic base
(mol.):water (mol) 100:(0.005-0.50):(5-200), preferably 100:(0.010-0.15):(20-80).
[0026] The second method for the preparation of said titanium-silicalite
(TS-1) molecular sieve according to the present invention is characterized
in that the method comprises that a synthesized TS-1 molecular sieve
having a MFI structure prepared by conventional method is mixed
with an organic base and water homogenously, then the mixture is
transferred to a sealed reaction vessel to react at 120-200.degree.
C. under autogenous pressure for 1-192 h, preferably at 150-180.degree.
C. for 2-120 h, and then the reaction product is recovered. Compared
with the first method, the second method is different in that it
saves the step of acid treatment and treats the above-said synthesized
TS-1 molecular sieve having a MFI-structure with an organic base
directly, wherein said organic base and its amount used are the
same as the afore-mentioned. In the second method, the organic base
treatment can be repeated once or several times.
[0027] The hollow cavity in the crystallite of said TS-1 molecular
sieve product obtained by the first method is larger than that produced
by the second method, while the second method can also achieve the
object of the invention.
DESCRIPTION OF THE DRAWING
[0028] FIG. 1 shows the XRD crystalline phase diagram of the sample
obtained in example 1.
[0029] FIGS. 2-13 are transmission electron microscopic (TEM) images
of the samples taken from comparative example 1 and examples 1-11
respectively.
[0030] FIGS. 14-25 are low-temperature N.sub.2 adsorption-desorption
isotherms of samples taken from comparative example 1 and examples
1-11 respectively.
[0031] According to the methods of this invention, the adoption
of acid-base treatment and/or organic base treatment has enabled
the ex-skeleton Ti to re-enter the skeleton of the TS-1 molecular
sieve, thus the amount of ex-skeleton TiO.sub.2 is reduced, while
the amount of effective Ti in the skeleton is increased, and as
a result, the reactivity of the titanium-silicalite molecular sieve
in catalytic oxidation is obviously higher than that prepared by
the prior art (see Example 12) and its activity stability is better
(see Example 13). Besides, the thin-wall and hollow-cavity structure
of the crystallites of said TS-1 molecular sieve of the invention
favors the diffusion of the molecules, particularty the larger molecules
among the reactants (e.g. the aromatic compounds) and reaction products
in the catalytic reactions, especially in the catalytic oxidations
of the aromatic or cyclic compounds.
[0032] The invention will be further described in combination with
various specific Examples. In the following examples, TPAOH was
the product of Tokyo Kasei Organic Chemicals, the other regents
were all the commercial products. The transmission electron microscopic
images of the titanium-silicalites were taken with a JEM-2000 FX-II
transmission electron microscope (TEM) of Japan Electron Corporation.
Benzene adsorption capacity was measured by the routine static adsorption
method. Determination of the low-temperature N.sub.2 adsorption-desorption
isotherms was carried out according to ASTM D4222-98 standard method.
COMPARATIVE EXAMPLE 1
[0033] This comparative example demonstrates the effect of a TS-1
molecular sieve synthesized in accordance with the procedure reported
in the reference (Zeolite, vol. 12 1992 pages 943-950), which
was different from the method of this invention.
[0034] 22.5 g of TEOS (tetraethyl orthosilicate) was mixed with
7.0 g of TPAOH solution and 59.8 g of distilled water thoroughly.
After hydrolyzing at 60.degree. C. under atmospheric pressure for
1.0 h, a TEOS hydrolyzed solution was obtained. To the resultant
solution, a solution composed of 1.1 g of tetrabutyl titanate and
5.0 g of anhydrous isopropanol was added slowly with stirring vigorously.
The mixture obtained was stirred at 75.degree. C. for 3 h to obtain
a clearly transparent colloid, which was transferred to a stainless
steel autoclave and was shelved under autogenous pressure at 170.degree.
C. with the temperature being kept constant for 6 days, thereafter
the mixture of crystallization resultants thus obtained was filtered,
washed with distilled water till pH=6-8 dried at 110.degree. C.
for 1 h, thus the as-synthesized TS-1 raw powder was obtained. The
as-synthesized TS-1 raw powder was calcined at 550.degree. C. in
air for 4 h, thus the TS-1 molecular sieve was obtained.
[0035] Transmission electron microscopic (TEM) image (magnification
50000:1)is shown in FIG. 2.
[0036] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 14.
[0037] X-ray diffraction crystalline phase diagram is similar to
the pattern as shown in FIG. 1.
EXAMPLE 1
[0038] The TS-1 molecular sieve obtained in Comparative Example
1 was mixed homogenously with a sulfuric acid solution and water
in a ratio of molecular sieve (g):sulfuric acid (mol):water (mol)=100:0.15:150.
Then, the mixture was reacted at 90.degree. C. for 5.0 h. After
filtration, washing and drying by routine methods, an acid-treated
TS-1 molecular sieve was obtained.
[0039] Said acid-treated TS-1 was mixed with triethanolamine, TPAOH
and water in a ratio of molecular sieve (g):triethanolamine (mol):TPAOH
(mol):water (mol)=100:0.20:0.15:180. Then, the mixture was transferred
to a stainless steel autoclave and the reaction was carried out
under autogenous pressure at 190.degree. C. with the temperature
being kept constant for 12 h. After cooling and pressure unloading,
routine filtration, washing, drying and calcination at 550.degree.
C. in air for 3 h, the modified TS-1 molecnlar sieve of this invention
was obtained.
[0040] Transmission electron microscopic (TEM) image (magnification
50000:1)is shown in FIG. 3.
[0041] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 15.
[0042] X-ray diffraction crystalline phase diagram is similar to
the pattern as shown in FIG. 1.
EXAMPLE 2
[0043] The TS-1 molecular sieve obtained in Comparative Example
1 was mixed homogenously with a hydrofluoric acid solution and water
in a ratio of molecular sieve (g):hydrofluoric acid (mol):water
(mol)=100:0.25:60. Then the mixture was reacted at 50.degree. C.
for 3.0 h. After routine filtration, washing and drying, an acid-treated
TS-1 molecular sieve was obtained.
[0044] Said acid-treated TS-1 molecular sieve was mixed homogenously
with TPAOH and water in a ratio of molecular sieve (g):TPAOH (mol):water
(mol)=100:0.010:80. Then the mixture was transferred to a stainless
steel autoclave and was shelved under autogenous pressure at 170.degree.
C. with the temperature being kept constant for 24 h. After cooling
and pressure unloading, routine filtration, washing, drying and
calcination at 550.degree. C. in air for 3 h, the modified TS-1
molecular sieve of this invention was obtained.
[0045] Transmission electron microscopic (TEM) image (magnification
50000:1)is shown FIG. 4.
[0046] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown FIG. 16.
[0047] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 3
[0048] The TS-1 molecular sieve obtained in Comparative Example
1 was mixed homogenously with a phosphoric acid solution and water
in a ratio of molecular sieve (g):phosphoric acid (mol):water (mol)=100:1.55:250.
Then, the mixture was reacted at 68.degree. C. for 0.3 h. After
routine filtration, washing and drying, an acid-treated TS-1 molecular
sieve was obtained.
[0049] Said acid-treated TS-1 molecular sieve was mixed homogenously
with hexanediamine and water in a ratio of molecular sieve (g):hexanediamine
(mol):water (mol)=100:0.50:200. Then the mixture was transferred
to a stainless steel autoclave and was shelved under autogenous
pressure at 140.degree. C. with the temperature being kept constant
for 6 days. After cooling and pressure unloading, routine filtration,
washing, drying and calcination at 550.degree. C. in air for 3 h,
the modified TS-1 molecular sieve of this invention was obtained.
[0050] Transmission electron microscopic (TEM) image (magnification
25000:1)is shown in FIG. 5.
[0051] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 17.
[0052] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 4
[0053] The TS-1 molecular sieve obtained in Comparative Example
1 was mixed homogenously with a ammonium nitrate solution and water
in a ratio of molecular sieve (g):ammonium nitrate (mol):water (mol)=100:3.25:200.
Then the mixture was reacted at ambient temperature (25.degree.
C.) for 1.5 h. After routine filtration, washing and drying, an
acid-treated TS-1 molecular sieve was obtained.
[0054] Said acid-treated TS-1 molecular sieve was mixed homogenously
with n-butyl amine and water in a ratio of molecular sieve (g):n-butyl
amine (mol):water (mol)=100:0.18:30. Then, the mixture was transferred
to a stainless steel autoclave and was shelved under autogenous
pressure at 160.degree. C. with the temperature being kept constant
for 4 days. After cooling and pressure unloading, routine filtration,
washing, drying and calcination at 500.degree. C. in air for 4 h,
the modified TS-1 molecular sieve of this invention was obtained.
[0055] Transmission electron microscopic (TEM) image (magnification
50000:1)is shown FIG. 6.
[0056] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown FIG. 18.
[0057] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 5
[0058] An as-synthesized TS-1 molecular sieve raw powder obtained
in Comparative Example 1 was mixed homogenously with a hydrochloric
acid solution and water in a ratio of molecular sieve (g):hydrochloric
acid (mol):water (mol)=100:0.75:260. Then, the mixture was reacted
at 15.degree. C. for 6.0 h. After routine filtration, washing and
drying, an acid-treated TS-1 molecular sieve was obtained.
[0059] Said acid-treated TS-1 molecular sieve was mixed homogenously
with butanediamine and water in a ratio of molecular sieve (g):butanediamine
(mol):water (mol)=100:0.30:10. Then, the mixture was transferred
to a stainless steel autoclave and was shelved under autogenous
pressure at 155.degree. C. with the temperature being kept constant
for 3 days. After cooling and pressure unloading, routine filtration,
washing, drying and calcination at 600.degree. C. in air for 2 h,
the modified TS-1 molecular sieve of this invention was obtained.
Transmission electron microscopic (TEM) image (magnification 50000:1)is
shown in FIG. 7.
[0060] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 19.
[0061] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 6
[0062] The TS-1 molecular sieve obtained in Comparative Example
1 was mixed homogenously with an oxalic acid solution and water
in a ratio of molecular sieve (g):oxalic acid (mol):water (mol)=100:4.5:30.
Then, the mixture was reacted at 80.degree. C. for 2.5 h. After
routine filtration, washing and drying, an acid-treated TS-1 molecular
sieve was obtained.
[0063] Said acid-treated TS-1 molecular sieve was mixed homogenously
with diethanolamine and water in a ratio of molecular sieve (g):diethanolamine
(mol):water (mol)=100:0.30:50. Then, the mixture was transferred
to a stainless steel autoclave and was shelved under autogenous
pressure at 165.degree. C. with the temperature being kept constant
for 2 days. After cooling and pressure unloading, routine filtration,
washing, drying and calcination at 550.degree. C. in air for 3 h,
the modified TS-1 molecular sieve of this invention was obtained.
[0064] Transmission electron microscopic (TEM) image (magnification
50000:1) is shown in FIG. 8.
[0065] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 20.
[0066] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 7
[0067] The TS-1 molecular sieve obtained in Comparative Example
1 was mixed homogenously with an ammonium fluoride solution and
water in a ratio of molecular sieve (g):ammonium fluoride (mol):water
(mol)=100:0.05:80. Then the mixture was reacted at 35.degree. C.
for 4.5 h. After routine filtration, washing and drying, an acid-treated
TS-1 molecular sieve was obtained.
[0068] Said acid-treated TS-1 molecular sieve was mixed homogenously
with tetraethylammonium hydroxide and water in a ratio of molecular
sieve (g):tetraethylammonium hydroxide (mol):water (mol)=100:0.25:60.
Then, the mixture was transferred to a stainless steel autoclave
and was shelved under autogenous pressure at 175.degree. C. with
the temperature being kept constant for 3 days. After cooling and
pressure unloading, routine filtration, washing, drying and calcination
at 550.degree. C. in air for 3 h, the modified TS-1 molecular sieve
of this invention was obtained.
[0069] Transmission electron microscopic (TEM) imagic (magnification
50000:1)is shown in FIG. 9.
[0070] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 21.
[0071] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 8
[0072] The procedures of Example 7 were repeated except for the
TS-1 obtained in Example 7 was used instead of the TS-1 molecular
sieve obtained in the comparative Example 1 and then the modified
TS-1 molecular sieve by the acid and base treatments more than once
according to this invention was obtained.
[0073] Transmission electron microscopic (TEM) image (magnification
50000:1)is shown in FIG. 10.
[0074] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 22.
[0075] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 9
[0076] The TS-1 molecular sieve obtained in Comparative Example
1 was mixed homogenously with tetraethylammonium hydroxide and water
in a ratio of molecular sieve (g):tetraethylammonium hydroxide (mol):water
(mol)=100:0.25:60. Then, the mixture was transferred to a stainless
steel autoclave and was shelved under autogenous pressure at 175.degree.
C. for 3 days. After cooling and pressure unloading, routine filtration,
washing, drying and calcination at 550.degree. C. in air for 3 h,
the modified TS-1 molecular sieve of this invention was obtained.
[0077] Transmission electron microscopic (TEM) image (magnification
50000:1)is shown in FIG. 11.
[0078] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 23.
[0079] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 10
[0080] The TS-1 molecular sieve obtained in Comparative Example
1 was mixed homogenously with triethanolamine and water in a ratio
of molecular sieve (g):triethanolamine (mol):water (mol)=100:0.25:60.
Then, the mixture was transferred to a stainless steel autoclave
and was shelved under autogenous pressure at 150.degree. C. for
3 days. After cooling and pressure unloading, routine filtration,
washing, drying and calcination at 550.degree. C. in air for 3 h,
the modified TS-1 molecular sieve of this invention was obtained.
[0081] Transmission electron microscopic (TEM) image (magnification
50000:1)is shown in FIG. 12.
[0082] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 24.
[0083] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 11
[0084] The TS-1 molecular sieve obtained in Comparative Example
1 was mixed homogenously with tetraethylammonium hydroxide, ethyl
amine and water in a ratio of molecular sieve (g):tetraethylammonium
hydroxide (mol):ethyl amine (mol):water (mol)=100:0.15:0.10:80.
Then, the mixture was transferred to a stainless steel autoclave
and was shelved under autogenous pressure at 175.degree. C. for
3 days. After cooling and pressure unloading, routine filtration,
washing, drying and calcination at 550.degree. C. in air for 3 h,
the modified TS-1 molecular sieve of this invention was obtained.
[0085] Transmission electron microscopic (TEM) image (magnification
50000:1)is shown in FIG. 13.
[0086] Low-temperature N.sub.2 adsorption-desorption isotherms
are shown in FIG. 25.
[0087] X-ray diffraction crystalline phase diagram is similar to
the pattern in FIG. 1.
EXAMPLE 12
[0088] This example shows the results of the catalytic oxidation
when the TS-1 molecular sieve samples obtained in Comparative Examples
and Examples according to the present invention were used for hydroxylation
of phenol.
[0089] The reactions were carried out in a three-necked flask fitted
with a condenser. The ratio of the reactants was TS-1 molecular
sieve:phenol:acetone=1:20.0:16.0 by weight. The mixture was heated
to 80.degree. C., then 30 wt % hydrogen peroxide according to the
ratio of phenol: H.sub.2O.sub.2=1:0.39 by weight was added in a
lot with stirring. The reaction was continued at the temperature
for 6 hours. The resultant products were analyzed on a Varian 3400
Chromatograph equipped with a 30 m.times.0.25 mm OV-101 capillary
column. The results are shown in Table 1. In table 1:
[0090] Phenol conversion %=(dihydroxyl-benzene, mol+quinone, mol)/fed
phenol, mol.times.100%
[0091] Dihydroxy-benzene selectivity %=(catechol, mol+Hydroquinone,
mol)/converted phenol, mol.times.100%
[0092] Catechol selectivity %=catechol, mol/all the products, mol.times.100%
[0093] Hydroquinone selectivity %=hydroquinone, mol/all the products,
mol.times.100%
[0094] Quinone selectivity %=quinone, mol/all the products, mol.times.100%
2TABLE 1 Phenol Dihydroxy- Conversion benzene Product Distribution
% Sample % Selectivity % CAT HQ PBQ 1 16.43 98.72 51.80 46.93 1.28
2 21.82 99.18 52.29 46.88 0.82 3 13.75 97.53 52.65 44.87 2.47 4
15.64 98.34 49.17 49.17 1.66 5 16.01 98.88 50.47 48.41 1.12 6 12.10
96.86 50.74 46.12 3.14 7 22.15 99.50 49.57 49.93 0.50 8 22.72 99.34
50.26 49.08 0.66 9 22.08 99.47 49.58 49.63 0.79 10 15.98 98.66 50.32
48.14 1.54 11 16.74 99.02 50.12 49.33 0.55 Compar. 1 12.54 90.35
45.37 44.98 9.65
[0095] CAT: catechol, HQ: hydroquinone, PBQ: quinone
EXAMPLE 13
[0096] This example shows the activity stability in the catalytic
oxidation when the TS-1 molecular sieve samples obtained in Comparative
Examples and Examples were used in hydroxylation of phenol.
[0097] TS-1 molecular sieve samples obtained in Compariative Example
1 and Example 1 were extruded into cylindrical pellets with a diameter
of 0.9.about.1.25 mm. The pellets were loaded into a fixed-bed reactor.
The reactants, which had a composition of phenol: acetone: H.sub.2O.sub.2=1:1.25:0.39
by weight, were passed through the catalyst bed at 80.degree. C.
at a rate of 1.0 g phenol per hour per g catalyst under the atmospheric
pressure. The samples were taken at intervals. The products were
analyzed on a Varian 3400 Chromatograph equipped with a 30 m.times.0.25
mm OV-101 capillary column. The results are shown in Table 2. The
definition of phenol conversion is the same as that in Example 12.
[0098] The results in Table 2 show that compared with the TS-1
molecular sieve obtained in comparative example 1 the TS-1 molecular
sieve provided by this invention has a higher catalytic oxidation
reactivity and a better activity stability. When the reaction was
carried out for 160 h without any regeneration, the TS-1 molecular
sieve catalyst according to the present invention kept a high catalytic
reactivity, whereas the reactivity of the TS-1 of the comparative
example dropped obviously. This shows that the TS-1 molecular sieve
sample according to the present invention has less ex-skeleton TiO.sub.2
so less tar and coke are produced and the catalyst can be scarecely
deactivated. Hence, the TS-1 molecular sieve of this invention has
a good stability of the catalytic reactivity. |