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 oxidizing trimethylphenol (TMP) to trimethylbenzoquinone
(TMBQ), the method comprising: mixing TMP, a molecular sieve containing
a transition metal in the framework, an oxidant and a solvent to
form a reaction system, the reaction system reacting at a temperature
of about room temperature to about 150.degree. C. to obtain TMBQ.
2. The method of claim 1 wherein a concentration of the TMP is
about 5-60% wt.
3. The method of claim 1 wherein the molecular sieve comprises
zeolite.
4. The method of claim 3 wherein the zeolite is selected from
the group consisting of ZSM-5 ZSM-11 Zeolite-Y, Zeolite-X, Zeolite-A
and .beta.-zeolite.
5. The method of claim 1 wherein the molecular sieve comprises
a mesoporous molecular sieve with hexagonal or cubic lattice structure.
6. The method of claim 5 wherein the mesoporous molecular sieve
contains a transition metal and Al in its framework.
7. The method of claim 1 wherein the transition metal is about
0.1-10% wt.of the molecular sieve.
8. The method of claim 1 wherein the transition metal is selected
from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn,
Nb, Mo, Ru and W.
9. The method of claim 1 wherein the concentration of the oxidant
is about 5-60% wt.
10. The method of claim 1 wherein the oxidant is selected from
the group consisting of H.sub.2O.sub.2 ROOH and O.sub.2 and R
is an organic group.
11. The method of claim 1 wherein the solvent is selected from
the group consisting of nitrites, alcohols, aldehydes, and carboxylic
acids.
12. The method of claim 1 wherein the temperature is about 40-80.degree.
C.
13. A method of forming a mesoporous molecular sieve containing
Cu and Al in the framework, the mesoporous molecular sieve can catalyze
the oxidation of trimethylphenol (TMP), comprising: mixing a Si-containing
compound, a Cu-containing compound, a Al-containing compound, a
template reagent and a solvent to obtain a mixing solution, the
Al/Si molar ratio being between about 0-0.2 the Cu/Si molar ratio
being between about 0-0.1 and the template reagent/Si molar ratio
being between about 0.1-2; adjusting the pH of the mixing solution
to be about 9-11 when the pH of the mixing solution is larger than
11 or adjusting the pH of the mixing solution to be about 0.1-3
when the pH of the mixing solution is 3-9; performing a hydrothermal
reaction under a temperature of about 80-200.degree. C. for about
1-10 days; separating a precipitate from the products of the hydrothermal
reaction; washing and then drying the precipitate; and calcining
the precipitate to remove the template reagent therein.
14. The method of claim 13 wherein the Si-containing compound
is an inorganic silicate or an organic Si-containing compound.
15. The method of claim 13 wherein the Al-containing compound
is an inorganic aluminate or an organic Al-containing compound.
16. The method of claim 13 wherein the Cu-containing compound
comprises an inorganic copper salt.
17. The method of claim 13 wherein the template reagent is selected
from the group consisting of a tetraethyl ammonium salt, a tetrapropyl
ammonium salt, a long-chain-alkyl-trimethyl ammonium salt, a copolymer
and combinations thereof.
18. The method of claim 17 wherein the carbon number of the long-chain-alkyl-trimethyl
ammonium salt is 12-20.
19. The method of claim 13 wherein the solvent is selected from
the group consisting of water, methanol, ethanol, propanol, butanol
and combinations thereof.
20. The method of claim 13 wherein the temperature of the calcining
step is about 500-800.degree. C.
Molecular sieve description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] 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
[0002] 1. Field of Invention
[0003] 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.
[0004] 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.
[0005] 2. Description of Related Art
[0006] 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.
[0007] 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.]
[0008] 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 Tl (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. Nos. 4491545 and 4828762).
[0009] 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.
[0010] 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.2O.sub.2 is used as the oxidant, the yield of TMBQ is the
highest (about 80%). However, the consumption of H.sub.2O.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.
[0011] Dutchman Jansen et al. used hetero-polyacids adsorbed on
active carbons to be the catalyst (J. J. Jansen, H. M. van Neldhuizen,
H. van Bekkum, J. Mol. Catal. A, 1996 107 241), therefore he hope
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.
[0012] 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.
[0013] 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 applicable 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.
[0014] 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.2O.sub.2
as the 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
[0015] The invention provides a method of oxidizing trimethylphenol
(TMP) to trimethylbenzoquinone (TMBQ).
[0016] 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.
[0017] 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.
[0018] 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 AlPO.sub.4-5 AlPO.sub.4-8 AlPO.sub.4-11
AlPO.sub.4-31 SAPO-37 and VPI-5 and the preferred ones are AlPO.sub.4-5
containing Ti, Co or Cu.
[0019] The oxidant's concentration described above is about 5-60%
wt., and it comprises H.sub.2O.sub.2 or ROOH such as t-BuOOH. If
oxygen gas is used as the oxidant, the O.sub.2 flows into the reaction
system at a flow rate of 1-20 mL/min.
[0020] The solvent's concentration described above is about 5-60%
wt., and it can be nitrites such as CH.sub.3CN; alcohols such as
methanol, ethanol, propanol and butanol; aldehydes such as CH.sub.3CHO
and PhCHO; and carboxylic acids such as acetic acid.
[0021] This invention also provides a method of forming a mesoporous
molecular sieve containing Cu and Al in the framework.
[0022] 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 mixing 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.
[0023] 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.
[0024] 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.
[0025] The pH of the mixing solution is adjusted to about 9-11
when the mixing solution's pH is larger than 11 or the mixing solution's
pH is adjusted to about 0.1-3 when the mixing 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.2SO.sub.4.
[0026] The mixing 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.
[0027] 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
[0028] I. Method of Synthesizing Molecular Sieves Containing Transition
Metals
[0029] This invention provides a method of synthesizing an aluminosilicate
molecular sieve containing transition metals. The synthesis steps
are as follow:
[0030] 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.
[0031] 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 tetratethyl 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.
[0032] 3. A hydrothermal reaction is performed for the resulting
solution of step 2 under a temperature of 80-200.degree. C.
[0033] 4. Precipitate is separated from the resulting solution
of step 3. The precipitate is washed with water and is then dried.
[0034] 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.
[0035] This invention also provides another method of synthesizing
an aluminophosphate molecular sieve. The synthesis steps are as
follows:
[0036] 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, inorganic phosphate or an organic
P-containing compound, and the aluminum-containing compound can
be, for example, inorganic aluminate or an organic Al-containing
compound.
[0037] 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.
[0038] 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.
[0039] 4. A hydrothermal reaction is performed for the resulting
solution of step 3 under a temperature of about 100-250.degree.
C.
[0040] 5. Precipitate is separated from the resulting solution
of step 4. The precipitate is washed with water and is then dried.
[0041] 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.
[0042] Several kinds of molecular sieves containing transition
metals are synthesized by methods mentioned above. These molecular
sieves comprise ZSM-5 (a microporous aluminosilicate zeolite), AlPO.sub.4-5
(a microporous aluminophosphate molecular sieve), and mseoporous
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.
[0043] 1. Synthesis method of MCM-41 containing Cu/Al
[0044] 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 solvent can be mixed to form a single-phase system.
[0045] 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 common used HCl, HNO.sub.3
or H.sub.2SO.sub.4.
[0046] 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.
[0047] 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.
[0048] 2. Characterization of MCM-41 containing Cu/Al
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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 0C2A, 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.
1TABLE 1 ICP-AES analysis results of MCM-41 containing Cu/Al. Atomic
Ratio of Atomic Ratio of Sample name Cu/Si (%) 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
[0053] II. Oxidation Reaction of TMP Catalyzed by a Molecular Sieve
in a Liquid-phase Reaction System
[0054] 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.
[0055] 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, AlPO.sub.4-5 AlPO.sub.4-8 AlPO.sub.4-11
ALPO.sub.4-31 SAPO-37 or VPI-5 and AlPO.sub.4-5 and those are
better to contain Ti, Co or Cu in their framework.
[0056] The oxidant's concentration is preferred to be about 5-60%
wt. and the oxidant can be, for example, H.sub.2O.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.
[0057] The concentration of the solvent is better to be about 5-60%
wt. The usable solvent can be nitriles such as methanenitrile (CH.sub.3CN),
alcohols such as methanol, ethanol, propanol or butanol, aldehyde
such as ethanal or benzoaldehyde (PhCHO), and carboxylic acids such
as acetic acid.
[0058] 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.2O.sub.2 (35% wt.) is added
to the mixture and stirred for a period of time. The amount of H.sub.2O.sub.2
added is equal to the equivalent number of the TMP.
[0059] 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.
[0060] Embodiment 1: Oxidizing TMP to TMBQ by Sample 2C2A
[0061] Using sample 2C2A as the catalyst, CH.sub.3CN as the solvent,
and H.sub.2O.sub.2 as the 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.3CN
added is 5 times of molar number of TMP, and the amount of H.sub.2O.sub.2
added is equal to the molar equivalent of TMP.
[0062] The analysis of the reaction's products is listed in Table
2. From Table 2 the 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.
2TABLE 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
[0063] Embodiment 2: The Effect of Cu/Al Content to the TMP Oxidation
3TABLE 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
[0064] 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.2O.sub.2:CH.sub.3CN 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.
[0065] 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 producing
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.
[0066] Embodiment 3: The Effect of Various Preparing Methods and
Lattice Structures of Cu-containing Molecular Sieves to TMP Oxidation
[0067] The product analysis of TMP oxidation catalyzed by various
preparing 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 is 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 (%).
[0068] Samples 1% Cu-APO-5 and 1% Cu-APO-5 in Table 4 represent
that Cu is added in the gel solution for preparing AlPO.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.2O.sub.3 is powder of aluminum
oxide.
[0069] 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 the 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
is not good as by sample 2C0A, 2C1A, and 2C2A, which are prepared
from the gel solution that Cu and Al are initially added therein.
[0070] 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 difference between the TMBQ yields is found (22.8
vs. 17.3).
4TABLE 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 MCu(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 MCu(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.2O.sub.3
35.1 0 0
[0071] The amount of catalyst added is 2 g, and the molar ratio
of TMP:H.sub.2O.sub.2:CH.sub.3CN=1:1:3. The reaction time is 20
min, and the reaction temperature is 60.degree. C.
[0072] Since Cu and Al are in the forms of CuO and Al.sub.2O.sub.3
attaching on the framework of molecular sieves that are prepared
by the immersing method, Al.sub.2O.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.2O.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.
[0073] For the Cu-containing molecular sieves of various lattice
structures, TMBQ is also obtained in the reaction catalyzed by AlPO.sub.4-5
(samples 1% Cu-APO-5 and 2% Cu-APO-5). However, the selectivity
of AlPO.sub.4-5 is worse than that of MCM-41.
[0074] Embodiment 4: V-containing MCM-41 Catalyze TMP Oxidation
5TABLE 5 V-containing MCM-41 catalyze TMP oxidation TMP:oxidant
Conversion of Selectivity of (molar ratio) Oxidant Solvent TMP (%)
TMBQ (%) 1:1 H.sub.2O.sub.2 CH.sub.3CN 55 >95 1:2 H.sub.2O.sub.2
CH.sub.3CN 70 >96 1:1 H.sub.2O.sub.2 Acetone 40 >97 1:1 TBHP
CH.sub.3CN 50 >15 1:2 TBHP CH.sub.3CN 60 >10
[0075] 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.
[0076] From Table 5 when H.sub.2O.sub.2 is used as the 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.3CN) 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.2O.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.
[0077] Embodiment 5: AlPO.sub.4-5 Containing Various Transition
Metals Catalyzes TMP Oxidation
6TABLE 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
[0078] The amount of catalyst added is 2 g, and TMP:H.sub.2O.sub.2:CH.sub.-
3COOH=10 g:12 mL:22 g. The reaction time is 3 hrs, and the reaction
temperature is 60.degree. C.
[0079] The product analysis of AlPO.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 AlPO.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-APO5 the highest and 1% Cu-APO-5
the is second. Therefore, the AlPO.sub.4-5 molecular sieve containing
Cu or Ti in its framework is best for converting TMP to TMBQ in
Table 6.
[0080] 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.
[0081] Embodiment 6: The Effect of Reaction Temperature to TMP
Oxidation Catalyzed by AlPO4-5 Molecular Sieve Containing Cu in
its Framework
7TABLE 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
[0082] The amount of 1% Cu-APO-5 added is 0.2 g. TMP:H.sub.2O.sub.2
:CH.sub.3COOH=1.0 g:1.2 mL:2.2 g. The reaction time is 3 hrs.
[0083] 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 can not 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 is further decreased.
[0084] Embodiment 7: The Effect of Various Solvents and Various
Oxidants to the TMP Oxidation
[0085] Sample 2C2A is used as the catalyst to explore the effect
of various solvents and oxidants. The solvents used have ethanol
(C.sub.2H.sub.5OH), ethanal (CH.sub.3CHO), methanenitrle (CH.sub.3CN)
and benzoaldehyde (PhCHO), whereas the oxidants used have hydrogen
peroxide (H.sub.2O.sub.2), TBHP (t-BUOOH), oxygen molecule (O.sub.2).
The results are listed in Table 8.
[0086] In Table 8 when hydrogen peroxide is used as the oxidant
and the C.sub.2H.sub.5OH 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.3CHO 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.3CN 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.2O.sub.2 or TBHP is used as the oxidant,
the solvent that is better to use is CH.sub.3CN or PhCHO, and PhCHO
is even better. If CH.sub.3CN or PhCHO is used as the solvent, the
oxidant that is better to be used is H.sub.2O.sub.2 or TBHP, and
TBHP is even better.
[0087] O.sub.2 is also used as the 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.3CN or PhCHO is used as the solvent.
TMP conversion of about 40% is detected after 2 hrs when PhCHO is
used as the 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.3CN 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.
8TABLE 8 the effect of various solvents and oxidants to TMP oxidation
Reaction TMBQ Solvent Oxident time Conv. (%) TON Yield (%) Select.
(%) C.sub.2H.sub.5OH H.sub.2O.sub.2 20 min 2.0 2.4 0 0 CH.sub.3CHO
H.sub.2O.sub.2 20 min 68.0 82 1.3 1.9 CH.sub.3CN H.sub.2O.sub.2
20 min 63.7 77 46.7 73.3 CH.sub.3CN TBHP 20 min 97.8 118 83.2 85.1
CH.sub.3CN O.sub.2 6 hrs 17.3 21 0 0 PhCHO H.sub.2O.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
[0088] The amount of the catalyst added is 0.2 g. The molar ratio
of TMP:oxidant (H.sub.2O.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.
[0089] Embodiment 8: The Catalytic Activity of Regenerate Catalyst
[0090] Samples 2C2A (MCM-41) and 1% Cu-APO-5 (AlPO.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.
[0091] 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.
9TABLE 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.aThe amount of catalyst
added is 2 g. The molar ratio of TMP:H.sub.2O.sub.2:CH.sub.3CN =
1:1:3. The reaction time is 20 min, and the reaction temperature
is 60.degree. C. .sup.bThe amount of catalyst added is 2 g. TMP:H.sub.2O.sub.2:CH.sub.3COOH
= 10 g:12 mL:22 g. The reaction time is 3 hrs, and the reaction
temperature is 60.degree. C.
[0092] From the preferred embodiments described above, various
molecular sieves containing various transition metals, especially
for 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:
[0093] 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%.
[0094] 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.
[0095] 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.
[0096] 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.
[0097] 5. The molecular sieve catalyst is solid. Therefore, the
separation of catalyst and 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.
[0098] 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. |