Molecular sieve abstract
A method of oxidizing trimethylphenol (TMP) to trimethylbenzoquinone
(TMBQ) by various molecular sieves containing various transition
metals. In this method, TMP, a molecular sieve containing a transition
metal in its framework, an oxidant and a solvent are mixed together
to form a reaction system. The reaction system reacting at a temperature
of about room temperature to 150.degree. C. to obtain TMBQ, and
the concentration of TMP is about 5-60% wt.
Molecular sieve claims
What is claimed is:
1. A method of preparing trimethylbenzoquinone (TMBQ) from trimethylphenol
(TMP) characterized in that the reaction is catalyzed by molecular
sieves containing copper and aluminum ions incorporated in the framework
with a proper oxidant and a carboxylic-acid-free solvent at a temperature
lower than 150.degree. C.
2. The method of claim 1 wherein the molecular sieves comprise
aluminophosphate molecular sieves of the crystalline structure selected
from the group consisting of AIPO.sub.4 -5 AIPO.sub.4 -8 AIPO.sub.4
-11 AIPO.sub.4 -31 and VPI-5.
3. The method of claim 1 wherein the molecular sieves comprise
zeolites of the crystalline structure selected from the group consisting
of ZSM-5 ZSM-11 zeolite-Y, zeolite-X, zeolite-A, and .beta.-zeolite.
4. The method of claim 1 wherein the molecular sieves comprise
mesoporous molecular sieves selected from the group consisting of
MCM-41 and MCM-48 structures.
5. The method of claim 1 wherein the copper and aluminum contents
in the molecular sieves is respectively ranged from 0.1-10% wt and
0.1-45% wt.
6. The method of claim 1 wherein the concentration of the TMP
is 5-60% wt.
7. The method of claim 1 wherein the proper oxidant is selected
from the group consisting of H.sub.2 O.sub.2 alkyl peroxide and
O.sub.2.
8. The method of claim 1 wherein the carboxylic-acid-free solvent
comprises nitrites selected from the group consisting of methanenitrile
(CH.sub.3 CN), and benzonitrile.
9. The method of claim 1 wherein the carboxylic-acid-free solvent
comprises alcohols selected from the group consisting of methanol,
ethanol, propanol, and butanol.
10. The method of claim 1 wherein the carboxylic-acid-free solvent
comprises acetone or aldehydes selected from the group consisting
of ethanal or benzoaldehyde (PhCHO).
11. The method of claim 1 wherein the temperature is 30-80.degree.
C.
12. A method of preparing trimethylbenzoquinone (TMBQ) from trimethylphenol
(TMP) characterized in that the reaction is catalyzed by molecular
sieves containing vanadium, chromium, manganese, iron or cobalt
ions in the framework with a proper oxidant and a carboxylic-acid-free
solvent at a temperature lower than 150.degree. C.
13. The method of claim 12 wherein the molecular sieves comprise
aluminophosphate molecular sieves of the crystalline structure selected
from the group consisting of AIPO.sub.4 -5 AIPO.sub.4 -8 AIPO.sub.4
-11 AIPO.sub.4 -31 and VPI-5.
14. The method of claim 12 wherein the molecular sieves comprise
zeolites of the crystalline structure selected from the group consisting
of ZSM-5 ZSM-11 zeolite-Y, zeolite-X, zeolite-A, and .beta.-zeolite.
15. The method of claim 12 wherein the molecular sieves comprise
mesoporous molecular sieves selected from the group consisting of
MCM-41 and MCM-48 structures.
16. The method of claim 12 wherein the vanadium, chromium, manganese,
iron or cobalt contents in the molecular sieves is respectively
ranged in 0.1-10% wt.
17. The method of claim 12 wherein the concentration of reactant
TMP is ranged in 5-60% wt.
18. The method of claim 12 wherein the proper oxidant is selected
from the group consisting of H.sub.2 O.sub.2 alkyl peroxide and
O.sub.2.
19. The method of claim 12 wherein the carboxylic-acid-free solvent
comprises nitrites selected from the group consisting of methanenitrile
(CH.sub.3 CN), and benzonitrile.
20. The method of claim 12 herein the carboxylic-acid-free solvent
comprises alcohols selected from the group consisting of methanol,
ethanol, propanol, and butanol.
21. The method of claim 12 wherein the carboxylic-acid-free solvent
comprises acetone or aldehydes selected from the group consisting
of ethanal or benzoaldehyde (PhCHO).
22. The method of claim 12 wherein the temperature is 30-80.degree.
C.
Molecular sieve description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application
serial no. 090100156 filed Jan. 3 2001 the full disclosure of
which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a synthetic method of molecular
sieves containing transition metals. More particularly, the present
invention relates to a synthetic method of a mesoporous molecular
sieve containing Cu and Al in its framework.
The present invention also relates to a method of oxidizing trimethylphenol
(TMP) to trimethylbenzoquinone (TMBQ) by using molecular sieves,
which comprise the molecular sieve containing Cu and Al in its framework,
as catalysts.
2. Description of Related Art
Recently, the global market of Vitamin E has dramatically increased.
The main markets are in medical ingredients and nutrition foods.
Since the starting material, i.e. 236-trimethyl-14-hydroquinone
(TMHQ), is not easily obtained in bulk, the price of Vitamin E is
quite high. Therefore, researchers have widely studied how to efficiently
manufacture TMHQ at a lower cost.
In the past two decades, many chemical processes have been developed
to manufacture TMHQ by using TMP as the starting material. Sumitomo
Chemical Company uses chlorine gas to chlorinate TMP, then nitric
acid is used to oxidize TMP to TMHQ (U.S. Pat. No. 3932475). The
advantage of this process is that the price of TMP is quite cheap,
but one problem is that it produces a lot of pollutants. More than
50 kg of pollutive effluent is produced for every kilogram of TMHQ.
[C. Mercier and P. Chabardes, in M. G. Scaros and M. Prunier (Eds.),
Catalysis of Organic Reactions, Marcel Decker, New York, 1994 pp.
213-221 ].
TMP is oxidized to TMBQ, and then TMBQ is hydrogenated to TMHQ
by other patents. Catalysts, which can be used in the oxidation
step, include MnO.sub.2 and saturated organic acids (U.S. Pat. No.
3927045), inorganic or organic acids of TI (III) (U.S. Pat. No.
3910967), chelating complexes of Co (U.S. Pat. No. 4250335),
complexes of Fe or Mn (U.S. Pat. No. 5712416), cupric oxide or
cuprous oxide (U.S. Pat. No. 4491545), and aqueous solutions (U.S.
Pat. No. 4828762) or saturated alcohol solutions (U.S. Pat. No.
5041572) of cuprous halide/alkaline metal halide. Generally used
catalysts in the hydrogenation step include platinum or palladium
supported on zeolites or aluminum oxide, and hydrogen gas is used
to hydrogenate TMBQ to TMHQ (U.S. Pat. No. 4491545 and U.S. Pat.
No. 4828762).
Some papers about oxidizing TMP to TMBQ are published, such as
Ito et al. (S. Ito, K. Aihara, M. Matsumoto, Tetrahedron Lett.,
1983 24 5249), have used many kinds of metal oxides and metal
salts as catalysts, acetic acid and 30% hydrogen peroxide solution
are respectively used as a solvent and an oxidant. They found that
the best reaction result was obtained when RuCl.sub.3 was used as
the catalyst. The yield of TMBQ was up to 90%. Since RuCl.sub.3
is readily soluble in the reaction solution, RuCl.sub.3 is hardly
separated from the solution to be reusable. Furthermore, the cost
of RuCl.sub.3 is quite high, and thus this method is not economic.
Japanese Shimizu et al. (M. Shimizu, H. Orita, T. Hagakawa, K.
Takehira, Tetrahedron Lett., 1989 30 471) and Russian Kholdeeva
et al. (O. A. Kholdeeva, A. V. Golovin, R. I. Maksimovskaya, I.
V. Kozhenikov, J. Mol. Catal., 1992 75 235) respectively use hetero-polyacids
and acetic acid to be the catalyst and the solvent. When 60% wt.
H.sub.2 O.sub.2 is used as the oxidant, the yield of TMBQ is the
highest (about 80%). However, the consumption of H.sub.2 O.sub.2
is very large, and the hetero-polyacids are too readily soluble
in water to be isolated from the reaction solution to be reused
again.
Dutchman Jansen et al. used hetero-polyacids adsorbed on active
carbons as catalyst (J. J. Jansen, H. M. van Neldhuizen, H. van
Bekkum, J. Mol. Catal. A, 1996 107 241), therefore he hoped to
increase the easiness of separating the catalyst from the reaction
solution. However, washout of hetero-polyacids adsorbed on active
carbons is still occurring, thus the practicability is not high.
The turn over number (TON) of catalysts used in the above references
is at most about 4-10. Most oxidation catalysts mentioned above
are soluble in organic solvents or water; therefore solvents are
needed for recycling these oxidation catalysts to extract them from
the reaction mixtures. This extraction procedure makes the whole
reaction process more complicated and it still has a large space
to improve.
The widest used molecular sieve is the zeolite, of which pore size
is in the microporous range, i.e. about 0.5-1 nm. Therefore, it's
only application was in catalyzing chemical reactions of small molecules.
However, the development of mesoporous molecular sieves, of which
pore size is about 2-10 nm, has made them applicable in catalyzing
chemical reaction of larger molecules, especially in cracking heavy
oil and production of drugs and fine chemicals. When transition
metal is added in the molecular sieve, the reaction types that can
be catalyzed by the molecular sieve have expanded from acid catalyzed
reaction to redox reaction.
In the last ten years, molecular sieves containing transition metal
have been popular to be used in synthesis of TMBQ in order to resolve
the problem of recovering catalysts from homogeneous reaction systems.
For example, liquid reaction system using zeolites containing Ti
or V as catalysts and aqueous solution of H.sub.2 O.sub.2 as oxidant
can effectively oxidize phenol to hydroquinone and catechol (J.
S. Reddy, S. Sivasanker and P. Ratnasamy, J. Mol. Catal., 1992
71 373 and A. V. Ramaswany, S. Sivasanker and P. Ratnasamy, Micro.
Mater., 1994 2 451). Molecular sieves containing copper ions
are used in decomposing NO, and those molecular sieves containing
Cu.sup.2+ are prepared by ion-exchange between cations of molecular
sieves and Cu.sup.2+.
SUMMARY OF THE INVENTION
The invention provides a method of oxidizing trimethylphenol (TMP)
to trimethylbenzoquinone (TMBQ).
In this method, TMP, a molecular sieve containing a transition
metal in its framework, an oxidant and a solvent are mixed to form
a reaction system, and the reaction system reacts at a suitable
temperature to obtain TMBQ. The concentration of the TMP is about
5-60% wt. The reaction temperature is about room temperature to
about 150.degree. C., the preferred reaction temperature is about
40-80.degree. C., and the more preferred temperature is about 50-60.degree.
C.
The molecular sieve that can be used in this invention comprises
a zeolite, a mesoporous molecular sieve of hexagonal or cubic lattice
structure, and an aluminophosphate molecular sieve. The transition
metal described above can be Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn,
Nb, Mo, Ru and W, and the amount of the transitioin metal is about
0.1-10% wt. of the molecular sieve.
The zeolite described above can be ZSM-5 ZSM-11 Zeolite-Y, Zeolite-X,
Zeolite-A or .beta.-zeolite. The mesoporous molecular sieve described
above comprises MCM-41 and MCM-48 and the preferred ones are MCM-41
containing V or Cu/Al. The aluminophosphate molecular sieve described
above comprises AIPO.sub.4 -5 AIPO.sub.4 -8 AIPO.sub.4 -11 AIPO.sub.4
-31 SAPO-37 and VPI-5 and the preferred ones are AIPO.sub.4-5
containing Ti, Co or Cu.
The oxidant's concentration described above is about 5-60% wt.,
and it comprises H.sub.2 O.sub.2 or ROOH such as t-BuOOH. If oxygen
gas is used as oxidant, the O.sub.2 flows into the reaction system
at a flow rate of 1-20 mL/min.
The solvent's concentration described above is about 5-60% wt.,
and it can be nitrites such as CH.sub.3 CN; alcohols such as methanol,
ethanol, propanol and butanol; aldehydes such as CH.sub.3 CHO and
PhCHO; and carboxylic acids such as acetic acid.
This invention also provides a method of forming a mesoporous molecular
sieve containing Cu and Al in the framework.
In this method, a Si-containing compound, a Cu-containing compound,
a Al-containing compound, a template reagent and a solvent are mixed
together to obtain a mixing solution. In the mixture solution, the
Al/Si molar ratio is between about 0-0.2 the Cu/Si molar ratio
is between about 0-0.1 and the template reagent/Si molar ratio
is between about 0.1-2.
The Si-containing compound can be an inorganic silicate such as
water glass (sodium silicate), or an organic Si-containing compound
such as tetraethoxysilicate (TEOS). The Cu-containing compound can
be an inorganic copper salt such as Cu(NO.sub.3).sub.2. The Al-containing
compound can be an inorganic aluminate such as sodium aluminate,
or an organic Al-containing compound such as triethoxyaluminate
or tripropoxyaluminate.
The template reagent can be a tetraethyl ammonium salt, a tetrapropyl
ammonium salt, a long-chain-alkyl-trimethyl ammonium salt, a copolymer
or combinations thereof. The carbon number of the long-chain-alkyl-trimethyl
ammonium salt is 12-20. The solvent can be water, methanol, ethanol,
propanol, butanol or combinations thereof. The only requirement
for mixing various solvents is that these solvents can form a single-phase
system.
The pH of the mixture solution is adjusted to about 9-11 when the
mixing solution's pH is larger than 11 or the mixture solution's
pH is adjusted to about 0.1-3 when the solution's pH is 3-9. The
adusting pH step can be accomplished by adding acids such as common
used HCl, HNO.sub.3 or H.sub.2 SO.sub.4.
The mixture solution undergoes a hydrothermal reaction under a
temperature of about 80-200.degree. C. for about 1-10 days to form
the mesoporous molecular sieves. Precipitate is separated from the
products of the hydrothermal reaction, and then it is washed and
dried. The precipitate is calcined at a temperature of about 500-800.degree.
C. to remove the template reagent in the mesoporous molecular sieve's
pores.
It is to be understood that both the foregoing general description
and the following detailed description are by example only, and
are intended to provide further explanation of the invention as
claimed.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
I. Method of Synthesizing Molecular Sieves Containing Transition
Metals
This invention provides a method of synthesizing an aluminosilicate
molecular sieve containing transition metals. The synthesis steps
are as follow: 1. Both the silicon-containing compound and the aluminum-containing
compound or the solutions of both compounds are mixed together,
wherein the Al/Si molar ration is 0 to 0.5. The silicon-containing
compound can be, for example, an inorganic silicate or an organic
Si-containing compound, and the aluminum-containing compound can
be, for example, an inorganic aluminate or an organic Al-containing
compound. 2. An organic template reagent and a salt of transition
metal (M) or solutions thereof are added to the reaction solution
of step 1 and the M/Si molar ratio is 0 to 0.5. The organic template
can be, for example, a tetraethyl ammonium salt, a tetrapropyl ammonium
salt, a long-chain-alkyl-trimethyl ammonium salt or other surfactants,
wherein the carbon number of the long-chain-alkyl-trimethyl ammonium
salt's long-chain-alkyl group is preferred to be 12 to 20 and more
preferred to be 16. 3. A hydrothermal reaction is performed for
the resulting solution of step 2 under a temperature of 80-200.degree.
C. 4. Precipitate is separated from the resulting solution of step
3. The precipitate is washed with water and is then dried. 5. The
precipitate is calcined under a temperature of about 500-800.degree.
C. to remove the organic template in the pores of the aluminosilicate
molecular sieve.
This invention also provides another method of synthesizing an
aluminophosphate molecular sieve. The synthesis steps are as follows:
1. Both the phosphorous-containing compound and the aluminum-containing
compound or the solutions of both compounds are mixed together,
wherein the Al/P molar ration is 0.5 to 1.5. The phosphorous-containing
compound can be, for example, an inorganic phosphate or an organic
P-containing compound, and the aluminum-containing compound can
be, for example, an inorganic aluminate or an organic Al-containing
compound. 2. A salt of transition metal (M) or a solution thereof
are added to the reaction solution of step 1 and M/Al molar ratio
is about 0 to 0.5. 3. An organic template reagent is added to the
resulting solution of step 2. The organic template can be, for example,
dipropyl amine, triethyl amine or tripropyl amine, wherein the preferred
organic template is triethyl amine. 4. A hydrothermal reaction is
performed for the resulting solution of step 3 under a temperature
of about 100-250.degree. C. 5. Precipitate is separated from the
resulting solution of step 4. The precipitate is washed with water
and is then dried. 6. The precipitate is calcined under a temperature
of about 500-800.degree. C. to remove the organic template in the
aluminophosphate molecular sieve's pores.
Several kinds of molecular sieves containing transition metals
are synthesized by methods mentioned above. These molecular sieves
comprise ZSM-5 (a microporous aluminosilicate zeolite), AIPO.sub.4
-5 (a microporous aluminophosphate molecular sieve), and mesoporous
MCM-41. Many molecular sieves containing transition metals are found
to have catalytic activity for oxidizing TMP to TMBQ, especially
the MCM-41 containing V or Cu/Al. Therefore, MCM-41 containing V
or Cu/Al will be the main examples for discussion described below.
1. Synthesis Method of MCM-41 Containing Cu/Al
A Si-containing compound, an Al-containing compound, a Cu-containing
compound, a template reagent and a solvent are mixed together to
form a mixture solution, wherein 0<Al/Si molar ratio.ltoreq.0.2
0<Cu/Si molar ratio.ltoreq.0.1 and 0.1.ltoreq.template/Si molar
ratio.ltoreq.2. The Si-containing compound can be, for example,
an inorganic silicate such as water glass, i.e. sodium silicate,
or an organic Si-containing compound such as tetraethoxysilicate
(TEOS). The Al-containing compound can be, for example, an inorganic
aluminate such as sodium aluminate or an organic Al-containing compound
such as triethoxyaluminate or tripropoxyaluminate. The Cu-containing
compound can be, for example, an inorganic copper salt such as Cu(NO.sub.3).sub.2.
The template reagent can be, for example, a tetraethyl ammonium
salt, a tetrapropyl ammonium salt, a long-chain-alkyl-trimethyl
ammonium salt, copolymer or combinations thereof. The preferred
carbon number of the long-chain-alkyl-trimethyl ammonium salt's
longest alkyl chain is 12 to 20. The solvent can be, for example,
water, methanol, ethanol, propanol, butanol or combinations thereof,
if the different solvents can be mixed to form a single-phase system.
If pH value of the mixture solution is larger than 11 for example,
when water glass is used as the Si source, the pH of the mixture
solution is adjusted to about 9-11. If pH value of the mixture solution
is between 3 to 9 for example, when TEOS is used as the Si source,
the pH of the mixture solution is adjusted to about 0.1-3. The pH
adjustment can use acids such as commonly used HCl, HNO.sub.3 or
H.sub.2 SO.sub.4.
The mixture solution undergoes a hydrothermal reaction at a temperature
of about 80-200.degree. C. for 1-10 days. Precipitate (i.e. MCM-41
molecular sieve) is then separated from the mixture solution, washed
with water and dried. Finally, the precipitate is calcined at a
preferred temperature of about 500-800.degree. C. to remove the
template reagent in the pores of MCM-41. A real synthetic example
will be given as follows.
4.25 g of cetyltrimethylammonium bromide (CTMABr) is dissolved
in 30 g of water to get a template solution. An appropriate amount
of Cu(NO.sub.3).sub.2 is added to 100 mL of water, then the mixture
is stirred to get a Cu(NO.sub.3).sub.2 solution. An appropriate
amount of NaAlO.sub.2 is added to 15 g of water, then the mixture
is stirred for 5 min; 5.33 g of water glass and 15 g of water are
then added to get a mixed solution of sodium aluminate and sodium
silicate. The Cu(NO.sub.3).sub.2 solution is added to the mixed
solution of sodium aluminate and sodium silicate, the template solution
is then added after stirring for 10 min. After stirring for 5 min,
the pH of the resulting solution is adjusted to 9.5 to 10. After
2 days of stirring, the solution undergoes the hydrothermal reaction
at a temperature of about 100.degree. C. for 7 days. Next, after
the solution's temperature is lowered to room temperature, the solution
is filtered to get the final powder product. The powder is washed
with a large amount of water then it is put into an oven to dry
at a temperature of about 50.degree. C. Finally, the powder is calcined
at a temperature of about 560.degree. C. for 12 hours to get MCM-41
containing Cu/Al in its framework.
2. Characterization of MCM-41 Containing Cu/Al
In the X-ray powder diffraction (XRD) spectrum of MCM-41 as synthesized,
diffraction peaks at 4.08 2.37 2.06 and 1.57 nm of d-spacing appear,
which individually represent the Miller index (100), (110), (200)
and (210) diffraction planes of hexagonal crystal structure. After
high-temperature calcining to remove CTMABr in the pores of MCM-41
diffraction peaks in XRD spectrum move toward lower d-spacing direction,
which is accompanied by the occurrence that the full-line-width
at half-maximum (FWHM) of diffraction peaks is decreased and the
intensity of diffraction peaks is increased. This XRD spectrum change
indicates that the structure of MCM-41 is condensed after calcination,
and therefore the pore size is decreased but the crystal structure
is improving.
For the MCM-41 with the same Al content but different Cu content,
the XRD spectra's diffraction peaks do not show large changes, but
the FWHM has increased as the Cu content of MCM-41 has increased.
For the MCM-41 with the same Cu content but different Al content,
the FWHM of the XRD spectra's diffraction peak becomes broader when
the Al content is greater than 3%. When the Al content is greater
than 10%, the crystal structure is poor and the diffraction peaks
move to lower d-spacing positions.
The XRD spectra's changes show that when Cu and/or Al content is
greater than a certain amount, the framework of MCM-41 is twisted.
Therefore, Cu and Al should mostly enter the framework of MCM-41
and the pores are hexagonally arranged. The MCM-41 as synthesized
can maintain the hexagonal-arranged pore structure after calcination
at the temperature of 560.degree. C.
Inductive Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES)
is used to detect the relative amount of various elements in samples,
which are listed in Table 1. The number before "C" in
the sample name represent the atomic ratio (%) of Cu/Si, and the
number before "A" in the sample name represent the atomic
ratio (%) of Al/Si. The Cu/Si ratio of MCM-41 products is usually
lower than that of the initial reaction solutions, which shows that
Cu is not entirely incorporated into the framework of MCM-41. As
for the sample OC2A, the Al/Si ratio is higher than that of the
initial reaction solution. It may be that a portion of skeletal
SiO.sub.2 is solubilized in aqueous solution, which makes the Al
content relatively increase. It is indicated that Al can more easily
replace skeletal Si than Cu.
TABLE 1 ICP-AES analysis results of MCM-41 containing Cu/Al. Sample
name Atomic Ratio of Cu/Si (%) Atomic Ratio of Al/Si (%) of MCM-41
Reactant Product Reactant Product 0C0A 0 0 0 0 0C2A 0 0 2 2.16 1C2A
1 0.83 2 1.35 2C0A 2 1.65 0 0 2C2A 2 1.74 2 1.71
II. Oxidation Reaction of TMP Catalyzed by a Molecular Sieve in
a Liquid-phase Reaction System
This invention provides a method of oxidizing TMP to produce TMBQ,
which is catalyzed by a molecular sieve. This method comprises a
reaction system, which includes TMP, a molecular sieve containing
a transition metal in its framework, an oxidant, and a solvent those
are mixed together to undergo a reaction under a suitable temperature
to obtain TMBQ. The concentration of TMP is about 5-60% wt. The
preferred reaction temperature is about room temperature to about
150.degree. C., and the more preferred reaction temperature is about
40.degree. C. to 80.degree. C.
The molecular sieve containing a transition metal in their framework
can be, for example, a zeolite, a mesoporous molecular sieve of
hexagonal or cubic crystal structure and an aluminophosphate molecular
sieve. The transition metal contained in the framework of the molecular
sieve can be, for example, Ti, V, Cr, Mn, Fe, Co, Ni,. Cu, Zn, Nb,
Mo, Ru or W, and the content of the transition metal in the framework
of the molecular sieve is about 0.1-10% wt. The zeolite can be,
for example, ZSM-5 ZSM-11 Zeolite-Y, Zeolite-X, Zeolite-A or .beta.-Zeolite.
The mesoporous molecular sieve can be, for example, MCM-41 (hexagonal
crystal structure) or MCM-48 (cubic crystal structure). The aluminophosphate
molecular sieve can be, for example, AIPO.sub.4 -5 AIPO.sub.4 -8
AIPO.sub.4 -11 AIPO.sub.4 -31 SAPO-37 or VPI-5 and AIPO.sub.4
-5 and those are better to contain Ti, Co or Cu in their framework.
The oxidant's concentration is preferred to be about 5-60% wt.
and the oxidant can be, for example, H.sub.2 O.sub.2 or alkyl peroxide
such as tert-butylhydroperoxide (t-BuOOH; abbreviated as TBHP).
If molecular oxygen is used as the oxidant, it is better to direct
about 1-20 mL/min of oxygen into the reaction system.
The concentration of the solvent is better to be about 5-60% wt.
The usable solvent can be nitriles such as methanenitrile (CH.sub.3
CN), alcohols such as methanol, ethanol, propanol or butanol, aldehyde
such as ethanal or benzoaldehyde (PhCHO), and carboxylic acids such
as acetic acid.
A working example is described as below. In a three-neck bottle,
2 g of a molecular sieve used as a catalyst is added in a solution
containing 10 g TMP (the molar ratio of TMP/solvent is 1/5) to form
a mixture and is then stirred. The mixture in the three-neck bottle
is then refluxed under a temperature of about 30-80.degree. C. Next,
an aqueous solution of H.sub.2 O.sub.2 (35% wt.) is added to the
mixture and stirred for a period of time. The amount of H.sub.2
O.sub.2 added is equal to the equivalent number of the TMP.
Gas Chromatography-Flame Ionization Detector (GC-FID) is used to
analyze the products of the reaction described above. A blank test
reaction, which doesn't add the molecular sieve, is also preformed
to compare the results of the reaction described above.
Embodiment Oxidizing TMP to TMBQ by Sample 2C2A
Using sample 2C2A as catalyst, CH.sub.3 CN as solvent, and H.sub.2
O.sub.2 as oxidant to catalyze the oxidation of TMP to TMBQ at a
temperature of 60.degree. C. The amount of sample 2C2A added is
2 g, the amount of TMP added is 10 g, the amount of CH.sub.3 CN
added is 5 times of molar number of TMP, and the amount of H.sub.2
O.sub.2 added is equal to the molar equivalent of TMP.
The analysis of the reaction's products is listed in Table 2. From
Table 2 conversion of TMP is more than 60% in the initial 20 min.
The conversion of TMP is increased as time passes, and the increasing
rate of the conversion is getting slower after 30 min. The yield
of TMBQ is also increased as time passes and reaches a maximum at
40 min.
TABLE 2 Analysis results of TMP oxidation. Reaction Time Conversion
of TMBQ (min) TMP (%) yield (%) Selectivity (%) 20 63.7 46.7 73.3
30 79.7 50.3 63.1 40 80.5 57.6 71.6
Embodiment 2
The Effect of Cu/Al Content to the TMP Oxidation
TABLE 3 The effect of the Cu/Al content to the TMP oxidation MCM-41
Conversion of TMBQ As catalyst TMP (%) yield (%) Conversion (%)
0C0A 1.1 0 0 2C0A 51.7 27.8 53.8 2C1A 60.5 40.6 67.1 2C2A 63.7 46.7
73.3
Using MCM-41 samples listed in Table 1 as the catalyst to catalyze
TMP oxidation, the molar ratio of the reaction system of TMP:H.sub.2
O.sub.2 :CH.sub.3 CN is 1:1:3 and 2 g of MCM-41 is added. The reaction
time is 20 min, and the reaction temperature is 60.degree. C. The
analysis of products is listed in Table 3.
From Table 3 when the MCM-41 without Cu and Al (sample 0C0A) is
used as the catalyst, only very low conversion of TMP is detected
and no TMBQ is produced. But as long as the MCM-41 contains Cu in
its framework (sample 2C0A, 2C1A, and 2C2A), the production of TMBQ
is observed. It is indicated that the Cu is the reactive center
for oxidizing TMP. From Table 3 it is also found that the yield
of TMBQ can be increased if MCM-41 contains Al in its framework.
Embodiment 3
The Effect of Various Preparation Methods and Lattice Structures
of Cu-containing Molecular Sieves to TMP Oxidation
The product analysis of TMP oxidation catalyzed by various preparation
methods and lattice structures of Cu-containing molecular sieves
are listed in Table 4. In Table 4 samples 2C0A, 2C1A, and 2C2A
are the same as those in Table 1 whereas samples 2C0A-imp, 2C1A-imp1
2C2A-imp1 and 2C2A-imp2 are prepared from sample 0C0A in Table
1. The preparation method comprises immersing the sample 0C0A in
an aqueous solution of Cu and/or Al for a period of time such as
for 3 hrs, and then distilling the sample under a vacuum. In Table
4 numbers before C of these sample names represent the Cu/Si atomic
ratios (%) of each sample, and numbers before A of these sample
names represent the Al/Si atomic ratios (%).
Samples 1% Cu-APO-5 and 1% Cu-APO-5 in Table 4 represent that Cu
is added in the gel solution for preparing AIPO.sub.4 -5 and the
amounts added are individually 1% and 2% of Cu/Si atomic ratio.
Sample Cu(NO.sub.3).sub.2(aq) means an aqueous solution of Cu(NO.sub.3).sub.2
and sample Al.sub.2 O.sub.3 is powder of aluminum oxide.
From Table 4 if MCM-41 containing Cu is prepared by immersion
(2C0A-imp), only trace amounts of TMBQ can be obtained. If MCM-41
is immersed in aqueous solution of Cu and Al (sample 2C1A-imp1
2C2A-imp1 and 2C2A-imp2) to be used as catalyst, the yield of TMBQ
can be greatly increased. However, the yield and selectivity of
TMBQ catalyzed by sample 2C1A-imp1 2C2A-imp1 and 2C2A-imp2 are
not good as by sample 2C0A, 2C1A, and 2C2A, which are prepared from
the gel solution that Cu and Al are initially added therein.
To understand whether the residual sodium ions affect the catalytic
activity of MCM-41 or not, the aluminum source is changed from NaAlO.sub.2
(samples 2C1A-imp1 and 2C2A-imp1) to Al.sub.2 (SO.sub.4).sub.3 (sample
2C2A-imp2). Comparing the reaction results of samples 2C2A-imp1
and 2C2A-imp2 no significant difference between the TMBQ yields
is found (22.8 vs. 17.3).
TABLE 4 The effect of various preparing method and lattice structure
of Cu-containing molecular sieves to TMP oxidation Conversion of
TMBQ Catalyst TMP (%) Yield (%) Selectivity (%) MCM-41 2C0A 51.7
27.8 53.8 2C1A 60.5 40.6 67.1 2C2A 63.7 46.7 73.3 MCM-41 immersed
in aqueous solution of 0.01 M Cu(NO.sub.3).sub.2 2C0A-imp 53.1 4.3
8.1 MCM-41 immersed in aqueous solution of 0.01 M{character pullout}Cu(NO.sub.3).sub.2
and NaAlO.sub.2 2C1A-imp1 58.7 15.2 25.9 2C2A-imp1 56.2 22.8 40.6
MCM-41 immersed in aqueous solution of 0.01 M{character pullout}Cu(NO.sub.3).sub.2
and Al.sub.2 (SO.sub.4).sub.3 2C2A-imp2 64.9 17.3 26.7 AlPO.sub.4
-5 1% Cu-APO-5 85.2 20.4 23.9 2% Cu-APO-5 84.8 30.4 35.8 No molecular
sieves added Cu(NO.sub.3).sub.2 (aq) 64.9 5.3 8.2 Al.sub.2 O.sub.3
35.1 0 0
The amount of catalyst added is 2 g, and the molar ratio of TMP:H.sub.2
O.sub.2 :CH.sub.3 CN=1:1:3. The reaction time is 20 min, and the
reaction temperature is 60.degree. C.
Since Cu and Al are in the forms of CuO and Al.sub.2 O.sub.3 attaching
on the framework of molecular sieves that are prepared by the immersing
method, Al.sub.2 O.sub.3 and aqueous solution of Cu(NO.sub.3).sub.2
are also used to catalyze the TMP oxidation. However, there is no
TMBQ produced in the reaction catalyzed by Al.sub.2 O.sub.3. If
the molar equivalent number of Cu(NO.sub.3).sub.2 used is the same
as that of catalyst 2C2A, only a small amount of TMBQ is detected.
This result indicates that Cu.sup.2+ is the active site of TMP oxidation,
and Cu.sup.2+ and Al.sup.3+ in the molecular sieve's framework have
a better catalytic activity. That is, the catalytic activity of
samples 2C0A, 2C1A and 2C2A is not from the Cu.sup.2+ dissolved
in the reaction solution.
For the Cu-containing molecular sieves of various lattice structures,
TMBQ is also obtained in the reaction catalyzed by AIPO.sub.4 -5
(samples 1% Cu-APO-5 and 2% Cu-APO-5). However, the selectivity
of AIPO.sub.4 -5 is worse than that of MCM-41.
Embodiment 4
V-containing MCM-41 Catalyzes TMP Oxidation
TABLE 5 V-containing MCM-41 catalyze TMP oxidation TMP:oxidant
Conversion of Selectivity of (molar ratio) Oxidant Solvent TMP (%)
TMBQ (%) 1:1 H.sub.2 O.sub.2 CH.sub.3 CN 55 >95 1:2 H.sub.2 O.sub.2
CH.sub.3 CN 70 >96 1:1 H.sub.2 O.sub.2 Acetone 40 >97 1:1
TBHP CH.sub.3 CN 50 >15 1:2 TBHP CH.sub.3 CN 60 >10
The amount of catalyst added is 0.05 g, that of TMP added is 0.7
g, and that of solvent added is 10 g. The reaction time is 6 hrs,
and the reaction temperature is 60.degree. C.
From Table 5 when H.sub.2 O.sub.2 is used as oxidant, a very high
selectivity of TMBQ, larger than 95%, can be obtained. For the solvent
used in the reaction system, the effect of methanenitrile (CH.sub.3
CN) is better than acetone. As for the oxidant used in the reaction
system, although a good conversion rate can be obtained by using
t-BuOOH to replace H.sub.2 O.sub.2 many by-products are obtained.
Besides, when the amount of oxidant added is more, the conversion
rate of TMP is higher. However, the selectivity of TMBQ is not affected
much by the amount of oxidant added.
Embodiment 5
AIPO.sub.4 -5 Containing Various Transition Metals Catalyzes TMP
Oxidation
TABLE 6 AlPO.sub.4 -5 containing various transition metals catalyzes
TMP oxidation Conversion of TMBQ Catalyst TMP (%) TON Yield (%)
Selectivity (%) 1% Ti-APO-5 84 203 78 93 1% V-APO-5 30 73 25 83
1% Cr-APO-5 67 162 58 86 1% Mn-APO-5 68 165 59 87 1% Fe-APO-5 61
148 51 84 1% Co-APO-5 73 177 65 92 1% Ni-APO-5 42 102 34 81 1% Cu-APO-5
91 220 72 79 1% Zn-APO-5 39 94 32 82
The amount of catalyst added is 2 g, and TMP:H.sub.2 O.sub.2 :CH.sub.3
COOH=10 g:12 mL:22 g. The reaction time is 3 hrs, and the reaction
temperature is 60.degree. C.
The product analysis of AIPO.sub.4 -5 molecular sieve containing
various transition metals catalyzing TMP oxidation is listed in
Table 6. The M/Si atomic ratio of transition metal (M) in the AIPO.sub.4
-5 (Si) is about 1%. The TMP conversions and the TMBQ yields vary
with various transition metals, wherein the conversion of TMP catalyzed
by 1% Cu-APO-5 is the highest and that by 1% Ti-APO-5 is the second.
As for the yield of TMBQ, 1% Ti-AIPO-5 is the highest and 1% Cu-APO-5
the is second. Therefore, the AIPO.sub.4 -5 molecular sieve containing
Cu or Ti in its framework is best for TMP to TMBQ in Table 6.
The number of TMBQ molecules produced by each transition metal,
i.e. turn over number (TON), is also shown in Table 6. It is indicated
that samples 1% Cu-APO-5 and 1% Ti-APO-5 have high catalytic activity,
since the TON of 1% Cu-APO-5 and 1% Ti-APO-5 are more than 200.
Embodiment 6
The Effect of Reaction Temperature to TMP Oxidation Catalyzed by
AIPO4-5 Molecular Sieve Containing Cu in its Framework
TABLE 7 The effect of temperature to the TMP oxidation Temperature
Conversion TMBQ (.degree. C.) (%) Yield (%) Selectivity (%) 25 0
0 -- 40 51 46 92 50 83 75 90 60 91 72 79 70 100 74 74 95 97 4.0
4.1 110 100 1.1 0.01
The amount of 1% Cu-APO-5 added is 0.2 g. TMP:H.sub.2 O.sub.2 :CH.sub.3
COOH=1.0 g:1.2 mL:2.2 g. The reaction time is 3 hrs.
In Table 7 the 1% Cu-APO-5 is used as the catalyst and seven reaction
temperatures (25 40 50 60 70 95 and 100.degree. C.) are used
for testing the temperature effect to the TMP oxidation. From Table
7 it is found that TMP oxidation cannot be processed at 25.degree.
C. When the temperature reaches 40-50.degree. C., the yield of TMBQ
is maintained at about 72-75%, and the selectivity of TMBQ is more
than 90%. When the temperature is raised to more than 70.degree.
C., the effect is increasing the yields of side products and the
selectivity of TMBQ is decreased. As for temperatures above 95.degree.
C., a secondary reaction produces side products with larger molecular
weight, and the yield and the conversion of TMBQ are further decreased.
Embodiment 7
The Effect of Various Solvents and Various Oxidants to the TMP
Oxidation
Sample 2C2A is used as catalyst to explore the effect of various
solvents and oxidants. The solvents used have ethanol (C.sub.2 H.sub.5
OH), ethanal (CH.sub.3 CHO), methanenitrile (CH.sub.3 CN) and benzoaldehyde
(PhCHO), whereas the oxidants used have hydrogen peroxide (H.sub.2
O.sub.2), TBHP (t-BUOOH), oxygen molecule (O.sub.2) The results
are listed in Table 8.
In Table 8 when hydrogen peroxide is used as the oxidant and the
C.sub.2 H.sub.5 OH is used as the solvent, the conversion of TMP
is very low. When the hydrogen peroxide is used as the oxidant and
the CH.sub.3 CHO is used as the solvent, the conversion of TMP is
much higher but the yield of TMBQ is very low. However, when the
CH.sub.3 CN and PhCHO is used as the solvent, both the conversion
of TMP and the yield of TMBQ are quite high. If TBHP is used as
the oxidant, the higher TMP conversion rate and TMBQ yield can be
obtained. Therefore, if H.sub.2 O.sub.2 or TBHP is used as the oxidant,
the solvent that is better to use is CH.sub.3 CN or PhCHO, and PhCHO
is even better. If CH.sub.3 CN or PhCHO is used as the solvent,
the oxidant that is better to be used is H.sub.2 O.sub.2 or TBHP,
and TBHP is even better.
O.sub.2 is also used as oxidant here. The reaction is processed
under an O.sub.2 flow rate of about 20 mL/min into the reaction
system, where the CH.sub.3 CN or PhCHO is used as solvent. TMP conversion
of about 40% is detected after 2 hrs when PhCHO is used as solvent,
and the selectivity of TMBQ is about 52%. As the reaction time increases,
the TMP conversion and TMBQ yield are also increased. After 6 hrs,
the TMP conversion is up to 82.4%, and the TMBQ yield is also up
to 54%. However, when CH.sub.3 CN is used as the solvent, no TMBQ
is detected after 6 hrs. Therefore, when the O.sub.2 is used as
the oxidant, PhCHO is better to be used as the solvent.
TABLE 8 the effect of various solvents and oxidants to TMP oxidation
TMBQ Reaction Conv. Yield Select. Solvent Oxidant time (%) TON (%)
(%) C.sub.2 H.sub.5 OH H.sub.2 O.sub.2 20 min 2.0 2.4 0 0 CH.sub.3
CHO H.sub.2 O.sub.2 20 min 68.0 82 1.3 1.9 CH.sub.3 CN H.sub.2 O.sub.2
20 min 63.7 77 46.7 73.3 CH.sub.3 CN TBHP 20 min 97.8 118 83.2 85.1
CH.sub.3 CN O.sub.2 6 hrs 17.3 21 0 0 PhCHO H.sub.2 O.sub.2 20 min
87.0 105 68.7 78.9 PhCHO TBHP 20 min 98.0 118 87.5 89.3 PhCHO O.sub.2
2 hrs 43.2 52 22.3 51.6 PhCHO O.sub.2 4 hrs 71.4 86 40.9 57.3 PhCHO
O.sub.2 6 hrs 82.4 96 44.6 54.1
The amount of the catalyst added is 0.2 g. The molar ratio of TMP
oxidant (H.sub.2 O.sub.2 or TBHP): solvent is 1:1:3. The O.sub.2
flow is 20 mL/min. The reaction temperature is 60.degree. C.
Embodiment 8
The Catalytic Activity of Regenerate Catalyst
Samples 2C2A (MCM-41) and 1% Cu-APO-5 (AIPO.sub.4 -5) are used
as the catalyst to compare the catalytic activity after catalyst
regeneration. The results are listed in Table 9. The method of forming
a regenerated catalyst is to separate the catalyst from the reaction
solution after the reaction, then the catalyst is washed by a large
amount of water. After washing it with water, the catalyst is dried
at room temperature and calcined at a temperature of about 560.degree.
C. for about 6 hrs.
From Table 9 the regenerated catalyst still has high catalytic
activity. The yield and selectivity of TMBQ is almost the same for
the catalyst before and after the regeneration. It is shown that
the catalyst, i.e. the molecular sieve, can be reused by regenerating
process and is very suitable to be used in industry.
TABLE 9 The effect of regenerate catalyst to the TMP oxidation
TMBQ Catalyst Conversion (%) Yield (%) Selectivity (%) 2C2A.sup.a
64 47 73 2C2A.sup.a (Regenerate) 59 43 72 1% Cu-APO-5.sup.b 91 72
79 1% Cu-APO-5.sup.b 76 61 80 (Regenerate) .sup.a The amount of
catalyst added is 2 g. The molar ratio of TMP:H.sub.2 O.sub.2 :CH.sub.3
CN = 1:1:3. The reaction time is 20 min, and the reaction temperature
is 60.degree. C. .sup.b The amount of catalyst added is 2 g. TMP:H.sub.2
O.sub.2 :CH.sub.3 COOH = 10 g:12 mL:22 g. The reaction time is 3
hrs, and the reaction temperature is 60.degree. C.
From the preferred embodiments described above, various molecular
sieves containing various transition metals, especially the MCM-41
containing Cu and Al, can be used as the catalyst to catalyze the
oxidation of TMP to TMBQ with a suitable oxidant and under a suitable
condition. The TMBQ is the main product of TMP's catalytic oxidation.
Therefore, compared with other literatures, this invention has the
following advantages: 1. Turn over number of TMBQ by per catalytic
active site is higher. The turn over number can be up to 200 by
using a suitable oxidant and under a suitable reaction condition.
Furthermore, the TMBQ yield can be up to more than 85%. 2. The reaction
temperature is lower for the TMP oxidation in this invention. The
reaction temperature is about 30-80.degree. C. The reaction time
needed is also shorter, only about 6-8 hrs. 3. Many oxidants are
applicable. Even if the most inert oxidant, O.sub.2 also can be
used as the oxidant, wherein the turn over number is about 50. Accordingly,
the oxidant can be properly chosen by the price of raw materials.
Therefore, the cost and throughput can be selectively adjusted.
4. The raw materials for preparing the catalyst are very cheap and
the preparation is very easy. Besides, the molecular sieve catalyst
is reusable. Therefore, the impact to the environment can be reduced
to the lowest level to fulfill the environmental. protection requirement
and economic effect. 5. The molecular sieve catalyst is solid. Therefore,
the separation of catalyst from the reaction solution is easy. This
makes the catalyst easily reusable, and the purification of TMBQ
is also easier to process. As a result, the production cost can
be largely reduced.
It will be apparent to those skilled in the art that various modifications
and variations can be made to the structure of the present invention
without departing from the scope or spirit of the invention. In
view of the foregoing, it is intended that the present invention
cover modifications and variations of this invention provided they
fall within the scope of the following claims and their equivalents. |